JP2005111968A - Image forming apparatus, image forming apparatus manufacturing method, image forming apparatus remodeling method, and sound quality evaluation method - Google Patents

Abstract

Sound quality can be evaluated by a single sound quality evaluation formula for sounds generated from a plurality of image forming apparatuses having different processing speeds and image forming apparatuses having a plurality of processing speeds / operation modes. To alleviate psychological discomfort by improving the unpleasant sound source that occurs during operation.
An image forming apparatus for forming an image on a recording paper, wherein a radiated sound emitted by the image forming apparatus when forming an image on the recording paper is spaced a predetermined distance from an end surface of the image forming apparatus. The sound is picked up at the position, and the discomfort index S is calculated using the acoustic physical quantity and the image forming speed obtained from the sound collection, and the discomfort index S is set to be equal to or less than the allowable value.
[Selection] FIG. 30

Description

  The present invention relates to an image forming apparatus, an image forming apparatus manufacturing method, an image forming apparatus remodeling method, and a sound quality evaluation method.

  In recent years, interest in noise problems has increased from the viewpoint of environmental friendliness, and there has been a strong demand for enhancing the quietness of office automation equipment in offices. In particular, image forming apparatuses represented by copying machines and laser printers have been made quieter, and noise standards during operation have become stricter than before.

  As a technique for solving the above-described noise problem, in a noise masking device such as a laser printer or a copying machine, a sounding body that generates a masking sound for masking this noise to a drive mechanism that is a source of noise during operation And a masking sound control means for controlling the sounding body to generate a masking sound having a frequency in a range including the main component frequency of the noise, thereby disclosing a technique for reducing noise discomfort (for example, , See Patent Document 1).

  However, in the technique disclosed in Japanese Patent Application Laid-Open No. 9-193506 of Patent Document 1, noise is generated by adding a masking sound to the generated sound without reducing the sound generated functionally from the main body. Levels rise and some people hear it can be noisy and uncomfortable. Moreover, since a sounding body for generating a masking sound and a control device for generating a masking sound only during the generation time of the sound to be masked are required, an extra space is required on the layout of the machine. This will cause a significant increase in costs.

  Now, in the OA equipment, the sound power level (ISO7779) is generally used as a method for evaluating noise. However, since the acoustic power level is a value of acoustic energy generated from office equipment such as a copying machine or a printer, there may be a case where the correlation with human subjective discomfort with noise is insufficient. For example, when listening to sounds with the same sound power level, there may be a difference in discomfort, and even if the sound power level is small, it may be heard as a very unpleasant sound. There is also.

  Therefore, in order to improve the office environment in the future, it is necessary not only to reduce the sound power level of the OA equipment but also to improve the sound quality. In order to improve sound quality, it is necessary to quantitatively measure the sound quality for grasping the current situation and to measure how much the effect is before and after the improvement. However, since sound quality is not a physical quantity, quantitative measurement cannot be performed. That is, even when compared by listening with the ear, the evaluation may differ depending on the person. Moreover, only qualitative expressions such as “sound quality has been improved a little” and “substantially improved” can be made. If the sound quality cannot be quantitatively expressed by physical characteristics, it is impossible to objectively evaluate the effect even if measures for improving the sound quality are taken. For this reason, it is necessary to conduct subjective evaluation experiments and perform statistical processing on the results to quantify sound quality.

  However, since these are values of acoustic energy generated from office equipment such as copying machines and printers, the correlation with human subjective discomfort with noise may not be very good. For example, when listening to sounds with the same sound pressure level (equivalent noise level Leq: average value of energy over the entire measurement time) and listening to the same sound, it is uncomfortable due to the difference in sound frequency distribution and the presence or absence of impact sound. There may be differences.

  Moreover, even if the value of the sound pressure level is small, it may be uncomfortable if a high frequency component, a pure sound component, or the like is included.

  Therefore, in order to improve the office environment in the future, it is necessary not only to evaluate and reduce the sound power level and sound pressure level of OA equipment, but also to simultaneously evaluate and improve sound quality.

  In order to evaluate and improve sound quality, it is necessary to quantitatively measure the sound quality for grasping the current situation and to measure how much it has been improved before and after the improvement. However, since sound quality is not a physical quantity, quantitative measurement cannot be performed. Therefore, it is difficult to set a target value.

  In the case of human sound quality evaluation, the expression is qualitative, such as “sound quality improved a little” or “substantially improved”. Furthermore, because of individual differences, it may be difficult to determine whether the evaluation differs from person to person or whether the obtained results can be generally said. If the sound quality is not quantitatively expressed by physical characteristics, it is impossible to objectively evaluate whether the measure was effective or how effective. For this reason, it is necessary to perform subjective evaluation experiments and perform statistical processing on the results to quantify sound quality.

By the way, a psychoacoustic parameter is known as a physical quantity for evaluating sound quality. Typical parameters include the following parameters (for example, refer to Non-Patent Document 1, where the following parentheses are units).
[1] Loudnes loudness (sone): loudness [2] Sharpness sharpness (acum): relative distribution of high frequency components [3] Tonality tonality (tu): articulation, content of pure tone components [4] Roughness roughness (asper): Roughness of sound [5] Fluctuatio Strength Fractation strain (vacil): Fluctuation intensity, roaring sound [6] Impulsiveness (iu): Impact [7] Relative approach: Sense of variation

  As any parameter increases, discomfort tends to increase. Among these, only loudness is standardized by ISO532B. For other parameters, the basic concept and definition are the same, but since the programs and calculation methods differ depending on the original research by the measuring instrument manufacturer, the measured values usually differ slightly from manufacturer to manufacturer. There are also original parameters developed by instrument manufacturers, such as impulsiveness and a relative approach.

  The noise generated from office automation equipment such as copiers and printers is composed of many timbres due to the complexity of the mechanism. For example, low-frequency heavy sounds, high-frequency high-pitched sounds, shocking sounds, etc. Are generated from a plurality of sound sources such as a motor, paper, and solenoid while changing with time.

  Although humans judge these sounds comprehensively to determine whether they are uncomfortable, it is considered that they are determined by weighting which part of the sound is particularly related to discomfort. That is, there are psychoacoustic parameters that have a large influence on discomfort due to the timbre of the machine and psychoacoustic parameters that have a small influence.

  The psychoacoustic parameters shown above tend to increase discomfort as the value of any psychoacoustic parameter increases. Among these, only loudness is standardized by ISO532B. For other psychoacoustic parameters, the basic idea is the same, but since the programs and calculation methods differ depending on the original research by each measuring instrument manufacturer, the measured values (output values) usually differ slightly from manufacturer to manufacturer. is there. If measures are taken to reduce all of these psychoacoustic parameters, the sound quality of the apparatus during operation can be improved.

  However, it takes a lot of effort to take measures for all psychoacoustic parameters. That is, noise generated from office automation equipment such as copiers and printers is a mixture of many timbres due to the complexity of the mechanism. For example, low-frequency heavy sounds, high-frequency high-pitched sounds, Generated sound (sudden noise) or the like is generated while changing in time from a plurality of sound sources such as various drive motors, recording paper, and solenoids.

  Humans judge these sounds comprehensively and determine whether or not they are uncomfortable. In this case, it is considered that weights determine which parts are particularly related to discomfort. That is, there are psychoacoustic parameters that have a large influence on discomfort and psychoacoustic parameters that have a small influence. Moreover, this depends on the tone that is emitted when the machine is in operation. For example, a high-speed printer that generates a large number of impact sounds feels the most unpleasant impact sound, while a low-speed, relatively quiet desktop printer generates less impact sounds. You may feel most uncomfortable. In this way, the uncomfortable part varies depending on the output speed of the image forming apparatus. Therefore, there is a case where the sound quality improvement is different between the low speed machine and the high speed machine. As a result, if a psychoacoustic parameter having a large improvement effect against discomfort is found and the sound quality is improved efficiently by improving the psychoacoustic parameter, the labor of repeating trial and error is reduced.

  Therefore, by combining psychoacoustic parameters having a large improvement effect against discomfort, weighting the psychoacoustic parameters to calculate a sound quality evaluation formula, and using this sound quality evaluation formula to calculate a subjective evaluation value for discomfort, Objective sound quality can be evaluated and sound quality can be improved. Further, it is possible to determine how much the subjective evaluation value for discomfort is to be eliminated, and to provide an image forming apparatus in which sound quality is improved so as to be equal to or less than that value. Can be solved.

JP-A-9-193506 The Japan Society of Mechanical Engineers "7th Design Optics and Systems Division Lecture" Aiming for an innovative leap in design and systems for the 21st century! "" November 10th and 11th, 1997 "Sound / Vibration and Design, Color and Design (1)" Section 089B

  There are various types of image forming apparatuses. That is, there are a small low-speed machine installed on the desk, a medium-sized medium-speed machine installed on the desk side, and a large high-speed machine installed slightly away from the desk on the office floor. Further, there is a case where the mode can be set depending on the resolution of the image, the thickness or the material of the sheet member that outputs a color or monochrome image on one machine. In this case, the image forming speed and the operating part of the machine may be different in one machine.

  These are used differently depending on the size of the office and the needs of the users. Naturally, the structure strength, the mechanical configuration, and the image forming process conditions differ depending on the machine, and the characteristics of the operating sound differ depending on the machine. Further, in the case of an image forming apparatus having a plurality of modes in one unit, there are a plurality of image forming speeds depending on the selected mode, and a part that operates inside the image forming apparatus differs, so that a plurality of different operating sounds are generated depending on the mode. There is a case. That is, it is conceivable that the impression of the operating sound varies depending on the type of the image forming apparatus, and the uncomfortable sound source varies.

  In one machine, when the image forming mode is changed, the rotational speed of the drive system is changed, the generated frequency is changed, and the number of times the impact sound is generated per unit time is changed. In addition, the sound that is generated varies depending on the part that operates. In other words, the impression of the operating sound varies depending on the mode, and the sound source that feels uncomfortable varies. Therefore, the sound source that requires sound quality improvement may differ depending on the type of image forming apparatus.

  Furthermore, depending on the mode of the image forming apparatus, the sound source that requires sound quality improvement may differ. In other words, in the case of an image forming apparatus that has various types of image forming apparatuses and a plurality of operation modes and generates different sounds depending on the mode, only a single apparatus or a single mode sound quality evaluation is required to improve sound quality. However, it was not sufficient, and it was necessary to evaluate the sound quality for each device and mode.

  The present invention has been made in view of the above, and evaluates the sound quality of sound generated from a plurality of image forming apparatuses having different processing speeds and image forming apparatuses having a plurality of processing speeds / operation modes. The objective is to alleviate psychological discomfort by improving the unpleasant sound source that is made possible by a single sound quality evaluation formula and during operation of the apparatus.

  In order to solve the above-described problems and achieve the object, the invention according to claim 1 is an image forming apparatus for forming an image on a recording sheet, and when the image is formed on the recording sheet. The radiated sound emitted by the image forming apparatus is collected at a position separated from the end face of the image forming apparatus by a predetermined distance, and the discomfort index S is calculated using the acoustic physical quantity and the image forming speed obtained from the collected sound. The discomfort index S is set to a predetermined value or less.

  According to the first aspect of the present invention, the discomfort index S derived by the sound quality evaluation formula using the acoustic physical quantity obtained from the sound emitted from the image forming apparatus is matched with the condition corresponding to the value of the image forming speed. By configuring the image forming apparatus, it is possible to reduce the sound generated by the image forming apparatus from causing discomfort to the user. Further, since the predetermined condition varies depending on the output value of the recording paper, the output value, that is, the low speed machine or the high speed machine has a plurality of operation modes, and the image forming speed varies in each mode. Even in a device, it is possible to obtain an uncomfortable index S using a single sound quality evaluation formula for an acoustic physical quantity obtained from the operation sound, and a condition under which an allowable value of the unpleasant index S varies depending on speed. By satisfy | filling, it can reduce the discomfort which an operation sound gives to a user regardless of which mode it operates.

According to a second aspect of the present invention, the acousto-physical quantity is a sound pressure level value, loudness value, sharpness value, tonality value, impulsiveness value obtained by collecting sound at a position approximately 1 m away from the end face of the image forming apparatus. The image forming speed is a ppm (number of output sheets of A4 landscape size paper per minute) value, the discomfort index S is calculated by the equation (a), and the discomfort index S satisfies the condition (b). It is characterized by satisfying.
S = A × (sound pressure level value) + B × (loudness value) + C × (sharpness value)
+ D x (Tonality value) + E x (Impulsiveness value) + F
0.037865 ≦ A ≦ 0.066678
0.126588 ≦ B ≦ 0.189486
0.367910 ≦ C ≦ 0.459389
2.532697 ≦ D ≦ 3.402664
1.132176 ≦ E ≦ 1.450574
−7.246314 ≦ F ≦ −4.7741981
(A)
S ≦ 0.4818Ln (ppm) −1.586 • (b)
14 ≦ ppm ≦ 65

  The invention according to claim 2 is characterized in that, in the invention according to claim 1, the discomfort index S derived by the sound quality evaluation formula (a) using the acoustic physical quantity obtained from the sound emitted by the image forming apparatus is 1 By configuring the image forming apparatus so as to meet the condition (b) corresponding to the output value of the recording paper per minute, it is possible to reduce the user's discomfort from the sound generated by the image forming apparatus. become. Further, since the condition (b) varies depending on the output value of the recording paper, the output value, that is, the low speed machine or the high speed machine has a plurality of operation modes and the image forming speed varies in each mode. Even in the device, the discomfort index S can be obtained from the acoustic physical quantity obtained from the operation sound by using one sound quality evaluation formula (a), and the allowable value of the discomfort index S varies depending on the speed. Since the condition is satisfied, it is possible to reduce discomfort that the operation sound gives to the user regardless of the mode.

According to a third aspect of the present invention, the acoustic physical quantity is a sound pressure level value, loudness value, sharpness value, tonality value, impulsiveness value obtained by collecting sound at a position approximately 1 m away from the end face of the image forming apparatus. The image forming speed is a ppm (number of output sheets of A4 landscape size paper per minute) value, the discomfort index S is calculated by the equation (c), and the discomfort index S satisfies the condition (b). It is characterized by satisfying.
S = A × (sound pressure level value) + B × (loudness value) + C × (sharpness value)
+ D x (Tonality value) + E x (Impulsiveness value) + F
A = 0.0522715
B = 0.1580369
C = 0.41366496
D = 2.96777803
E = 1.291173747
F = −5.999889619
(C)
S ≦ 0.4818Ln (ppm) −1.586 • (b)
14 ≦ ppm ≦ 65

  Further, the invention according to claim 3 is the invention according to claim 1, wherein the discomfort index S derived from the sound quality evaluation equation (c) using the acoustic physical quantity obtained from the sound emitted from the image forming apparatus is 1 By configuring the image forming apparatus so as to meet the condition (b) corresponding to the output value of the recording paper per minute, it is possible to reduce the user's discomfort from the sound generated by the image forming apparatus. become. Further, since the condition (b) varies depending on the output value of the recording paper, the output value, that is, the low speed machine or the high speed machine has a plurality of operation modes and the image forming speed varies in each mode. Even in a device, it is possible to obtain the discomfort index S from the acoustic physical quantity obtained from the operation sound using one sound quality evaluation formula (c), and the allowable value of the discomfort index S depends on the speed. Since the fluctuating conditions are satisfied, it is possible to reduce discomfort given to the user by the operation sound regardless of the mode.

According to a fourth aspect of the present invention, the acousto-physical quantity is a sound pressure level value, loudness value, sharpness value, tonality value, impulsiveness value obtained by collecting sound at a position approximately 1 m away from the end face of the image forming apparatus. The image forming speed is a value of v: mm / s, the discomfort index S is calculated by the equation (a), and the discomfort index S satisfies the condition (d).
S = A × (sound pressure level value) + B × (loudness value) + C × (sharpness value)
+ D x (Tonality value) + E x (Impulsiveness value) + F
0.037865 ≦ A ≦ 0.066678
0.126588 ≦ B ≦ 0.189486
0.367910 ≦ C ≦ 0.459389
2.532697 ≦ D ≦ 3.402664
1.132176 ≦ E ≦ 1.450574
−7.246314 ≦ F ≦ −4.7741981
(A)
S ≦ 0.4248Ln (v) −2.4301 (d)
62.5 ≦ v ≦ 362

  According to the fourth aspect of the present invention, in the invention according to the first aspect, the image with respect to the discomfort index S derived by the sound quality evaluation formula (a) using the acoustic physical quantity obtained from the sound emitted by the image forming apparatus. By configuring the image forming apparatus so as to meet the condition (d) corresponding to the forming speed, it is possible to reduce discomfort given to the user by the sound generated by the image forming apparatus. Further, since the condition (d) varies depending on the image forming speed, even a low-speed machine or a high-speed machine has a plurality of operation modes and the like, and an apparatus in which the image forming speed fluctuates in each mode. Since the discomfort index S can be obtained from the acoustic physical quantity obtained from the operation sound by using one sound quality evaluation formula (a), and the permissible value of the discomfort index S satisfies the condition that varies depending on the speed. In any mode, it is possible to reduce the discomfort that the operation sound gives to the user.

According to a fifth aspect of the present invention, the acousto-physical quantity is a sound pressure level value, loudness value, sharpness value, tonality value, impulsiveness value obtained by collecting sound at a position approximately 1 m away from the end face of the image forming apparatus. The image forming speed is a value of v: mm / s, the discomfort index S is calculated by the equation (c), and the discomfort index S satisfies the condition (d).
S = A × (sound pressure level value) + B × (loudness value) + C × (sharpness value)
+ D x (Tonality value) + E x (Impulsiveness value) + F
A = 0.0522715
B = 0.1580369
C = 0.41366496
D = 2.96777803
E = 1.291173747
F = −5.999889619
(C)
S ≦ 0.4248Ln (v) −2.4301 (d)
62.5 ≦ v ≦ 362

  According to the fifth aspect of the present invention, in the first aspect of the present invention, an image with respect to the discomfort index S derived by the sound quality evaluation formula (c) using the acoustic physical quantity obtained from the sound emitted from the image forming apparatus. By configuring the image forming apparatus so as to meet the condition (d) corresponding to the forming speed, it is possible to reduce discomfort given to the user by the sound generated by the image forming apparatus. Further, since the condition (b) varies depending on the image forming speed, even a low-speed machine or a high-speed machine has a plurality of operation modes and the like, and an apparatus in which the image forming speed fluctuates in each mode. The acoustic physical quantity obtained from the operating sound can be obtained by using one sound quality evaluation formula (d), and the discomfort index S satisfies the condition that the allowable value of the discomfort index S varies depending on the speed. In any mode, it is possible to reduce the discomfort that the operation sound gives to the user.

  Further, in the invention according to claim 6, in the plurality of image forming apparatuses having different image forming speeds or driving units of the image forming means, or operations, the discomfort index S is independent of the image forming speed and the image forming mode. The above condition is satisfied.

  Further, in the invention according to claim 6, in the invention according to any one of claims 1 to 5, even when the operation sound is operated in any of the operation modes selected by the operation control means, the operation sound is generated by the user. Discomfort can be reduced.

  In the invention according to claim 7, the sound collection position is a near-site position defined in ISO (International Organization for Standardization) 7779, and at least the sound collection position in the direction of the front of the apparatus (surface with the operation unit). The discomfort index S calculated from the sound result satisfies the condition.

  According to a seventh aspect of the present invention, in the invention according to any one of the first to sixth aspects, sound collection is performed at a position on the front side of the image forming apparatus in which the user of the image forming apparatus is likely to be normally positioned. By configuring the image forming apparatus so that the allowable value of the discomfort index S obtained from the result satisfies the above-described conditions, it is possible to reduce discomfort given to the user by the operation sound of the image forming apparatus.

  According to an eighth aspect of the present invention, the sound collection position is a neighbor position defined by ISO (International Organization for Standardization) 7779, and each of the sound collection results of sound in four directions, front, rear, left, and right of the device. The average value of the discomfort index S calculated from the above satisfies the condition.

  The invention according to claim 8 is the invention according to any one of claims 1 to 6, wherein the discomfort index S is derived from the sound collected in the four directions of the image forming apparatus, and the average value thereof is calculated. By configuring the image forming apparatus to satisfy the condition, it is possible to reduce on average the discomfort that the operation sound gives to the user regardless of the direction of the user.

  According to a ninth aspect of the present invention, the sound collection position is a neighbor position defined by ISO (International Organization for Standardization) 7779, and at least the sound collection of sound in any one of the front, rear, left, and right directions of the apparatus. The discomfort index S calculated from the result satisfies the condition.

  In the invention according to claim 9, in the invention according to any one of claims 1 to 6, the discomfort index S derived from the sound collected on at least one direction side of the image forming apparatus satisfies the condition. By configuring the image forming apparatus, it is possible to reduce discomfort caused by the operation sound of the image forming apparatus with respect to the user on the direction side.

  In the invention according to claim 10, the sound collection position is a neighbor position defined by ISO (International Organization for Standardization) 7779, and each of sound collection results of sound in four directions, front and rear, left and right of the device. All the discomfort indices S calculated from the above conditions satisfy the above condition.

  The invention according to claim 10 is the discomfort index derived from sounds collected in all directions in the front-rear and left-right directions of the image forming apparatus according to any one of claims 1-6. By configuring the image forming apparatus so that the allowable value of S satisfies the condition, the user can reduce discomfort caused by the operation sound of the image forming apparatus in any direction.

  According to an eleventh aspect of the present invention, there is provided a sound reduction means for reducing a sound generated by the apparatus when an image is formed on the recording paper.

  According to the eleventh aspect of the invention, in the invention according to any one of the first to tenth aspects, it is possible to reduce the sound generated by the image forming apparatus during image formation by the sound reducing means, and the image formation. The discomfort index S derived from the sound emitted from the apparatus satisfies the condition, and the discomfort given to the user by the sound emitted from the image forming apparatus can be reduced.

  The invention according to claim 12 further includes a stepping motor that drives a predetermined portion during image formation on the recording paper, and a bracket member that holds the stepping motor, and the sound reduction means includes It has the elastic body arrange | positioned by interposing between a stepping motor and the said bracket member, It is characterized by the above-mentioned.

  Further, the invention according to claim 12 is the invention according to claim 11, wherein the vibration transmitted during the operation of the stepping motor is not directly transmitted to the bracket member, but the vibration transmitted to the bracket member is absorbed by the elastic body. The sound generated due to this vibration can be reduced.

  The invention according to claim 13 further includes a stepping motor that drives a predetermined portion during image formation on the recording paper, and the sound reduction means has a drive control means that microsteps the stepping motor. It is characterized by that.

  The invention according to claim 13 is the stepping motor according to the invention according to claim 11, wherein the stepping motor has a step angle smaller than the step angle of a normal stepping motor mechanically determined by micro-step driving the stepping motor. It becomes possible to drive the rotor of the stepping motor, and the generation of vibrations is suppressed.

  The invention according to claim 14 further includes a motor for driving a predetermined portion during image formation on the recording paper, and the sound reduction means includes a Helmholtz resonator disposed in the vicinity of the motor. It is characterized by being.

  The invention according to claim 14 is the invention according to claim 11, wherein the Helmholtz resonator confines the sound component of the Helmholtz resonance frequency determined from the shape and the like in the cavity, that is, the sound component of the resonance frequency. By installing a Helmholtz resonator in the vicinity having a resonance frequency corresponding to the main frequency component of the sound emitted by the motor, it is possible to reduce the amount of sound generated by the motor leaking outside the device. .

  The invention according to claim 15 further includes a cylindrical image carrier having a hollow portion and charging means for charging the surface of the image carrier, and the sound reduction means includes the image carrier. It has a damping member for suppressing vibration of the image carrier in the hollow portion.

  According to the fifteenth aspect of the present invention, in the invention according to the eleventh aspect, when the charging means is charged to the image carrier, the image carrier vibrates due to the charging action. Although sound is generated, vibration generated in the image carrier can be suppressed by the damping member.

  The invention according to claim 16 further comprises a flexible sheet for guiding the recording paper along a predetermined conveyance path, and an end portion in contact with the conveyed recording paper is bent of the flexible sheet. It is characterized by comprising a guide member which is a part.

  According to the sixteenth aspect of the present invention, in the invention according to the eleventh aspect, the bent portion of the flexible sheet in the guide member is configured to come into contact with the recording paper to be conveyed, thereby generating the contact. Sound can be reduced. In other words, when the flexible sheet has a predetermined size, it is usually cut, but the cut portion of the flexible sheet has burrs or the like, and when this portion comes into contact with the recording paper, an irritating sound is generated. On the other hand, according to the present invention, it is possible to reduce the generation of harsh sounds by configuring the bent portion to contact the recording paper instead of the cut portion as described above.

  The invention according to claim 17 is characterized in that the toner used for image formation on the recording paper is a toner containing wax.

  According to the seventeenth aspect of the present invention, in the invention according to the eleventh aspect, by using a toner containing wax, in order to improve the separation between the fixing member and the recording paper during the fixing process in the image formation. There is no need to perform operations such as oil application on the fixing member. Therefore, it is possible to reduce the sound generated with the oil application operation.

  According to an eighteenth aspect of the present invention, the sound reducing means is configured so that the operation of the electromagnetic clutch provided in each of the paper feed conveyance paths having a plurality of paper feed stages is an electromagnetic clutch that is higher than the paper feed stage to be used. It is characterized by comprising a sheet feeding / conveying control means to be controlled.

  Further, the invention according to claim 18 is the invention according to claim 11, wherein only the electromagnetic clutch of the paper feed stage to be used is operated to reduce the metal impact sound, thereby reducing the impulsiveness value (impact sound value). ) Can be lowered.

According to a nineteenth aspect of the present invention, there is provided a method of manufacturing an image forming apparatus for forming an image on a recording paper, wherein the sound collecting position is approximately 1 m away from the end face of the image forming apparatus to be manufactured. Sound pressure level value, loudness value, sharpness value, tonality value, impulsiveness value of acoustic physical quantity obtained from sound emitted by the image forming apparatus when image formation is performed on the recording paper, and per minute A design step of designing each part of the apparatus using the output numerical value (ppm) of the recording paper (A4 size lateral direction) so that the discomfort index S calculated by the following equation (a) satisfies the following condition (b): ,
S = A × (sound pressure level value) + B × (loudness value) + C × (sharpness value)
+ D x (Tonality value) + E x (Impulsiveness value) + F
0.037865 ≦ A ≦ 0.066678
0.126588 ≦ B ≦ 0.189486
0.367910 ≦ C ≦ 0.459389
2.532697 ≦ D ≦ 3.402664
1.132176 ≦ E ≦ 1.450574
−7.246314 ≦ F ≦ −4.7741981
(A)
S ≦ 0.4818Ln (ppm) −1.586 • (b)
14 ≦ ppm ≦ 65
And a manufacturing step of manufacturing the image forming apparatus according to the design contents made by the designing step.

  According to the nineteenth aspect of the present invention, in designing an image forming apparatus, the discomfort index derived from the sound quality evaluation formula (a) using the acoustic physical quantity obtained from the sound collection result of the sound emitted by the image forming apparatus. With respect to S, each part of the apparatus is designed to meet the condition (b) corresponding to the output value of the recording paper per minute, and it is possible to manufacture an image forming apparatus based on the design contents. Become. Further, since the condition (b) varies depending on the output value of the recording paper, the output value, that is, the low speed machine or the high speed machine has a plurality of operation modes and the image forming speed varies in each mode. Even when the device is manufactured and provided, the discomfort index S can be obtained from the acoustic physical quantity obtained from the operation sound by using one sound quality evaluation formula (a), and the allowable value of the discomfort index S It is possible to satisfy the condition that fluctuates depending on the speed.

According to a twentieth aspect of the present invention, there is provided a method of manufacturing an image forming apparatus having a plurality of image forming speeds / a plurality of operations of different modes and forming an image on recording paper, and is a manufacturing object. The sound physical quantity loudness value, the sharpness value, the tonality value obtained from the sound emitted by the apparatus when image formation is performed on the recording paper, which is collected at a sound collection position approximately 1 m away from the end face of the image forming apparatus, Using the impulsiveness value and the output value (ppm) of the recording paper per minute (A4 size in the horizontal direction), the discomfort index S calculated by the following equation (c) satisfies the following condition (b): Design steps for designing each part of the device,
S = A × (sound pressure level value) + B × (loudness value) + C × (sharpness value)
+ D x (Tonality value) + E x (Impulsiveness value) + F
A = 0.0522715
B = 0.1580369
C = 0.41366496
D = 2.96777803
E = 1.291173747
F = −5.999889619
(C)
S ≦ 0.4818Ln (ppm) −1.586 • (b)
14 ≦ ppm ≦ 65
And a manufacturing step of manufacturing the image forming apparatus according to the design contents made by the designing step.

  According to the twentieth aspect of the present invention, in designing an image forming apparatus, the discomfort index derived from the sound quality evaluation formula (c) using the acoustic physical quantity obtained from the sound collection result of the sound emitted by the image forming apparatus. With respect to S, each part of the apparatus is designed to meet the condition (b) corresponding to the output value of the recording paper per minute, and it is possible to manufacture an image forming apparatus based on the design contents. Become. Further, since the condition (b) varies depending on the output value of the recording paper, the output value, that is, the low speed machine or the high speed machine has a plurality of operation modes and the image forming speed varies in each mode. Even when the device is manufactured and provided, it is possible to obtain the discomfort index S from the acoustic physical quantity obtained from the operation sound using one sound quality evaluation formula (c), and the discomfort index S It is possible to satisfy the condition that the allowable value varies depending on the speed.

According to a twenty-first aspect of the present invention, there is provided a method for manufacturing an image forming apparatus having a plurality of image forming speeds / a plurality of operations of different modes and forming an image on a recording sheet, and the image to be manufactured. A sound pressure level value, a loudness value of an acoustic physical quantity obtained from a sound emitted from the image forming apparatus when an image is formed on the recording paper, which is collected at a sound collecting position approximately 1 m away from an end surface of the forming apparatus; Using the sharpness value, the tonality value, the impulsiveness value, and the image forming speed (v: mm / s) for the recording paper, the discomfort index S calculated by the following equation (a) is as follows: A design step of designing each part of the device to satisfy
S = A × (sound pressure level value) + B × (loudness value) + C × (sharpness value)
+ D x (Tonality value) + E x (Impulsiveness value) + F
0.037865 ≦ A ≦ 0.066678
0.126588 ≦ B ≦ 0.189486
0.367910 ≦ C ≦ 0.459389
2.532697 ≦ D ≦ 3.402664
1.132176 ≦ E ≦ 1.450574
−7.246314 ≦ F ≦ −4.7741981
(A)
S ≦ 0.4248Ln (v) −2.4301 (d)
62.5 ≦ v ≦ 362
And a manufacturing step of manufacturing the image forming apparatus according to the design contents made in the designing step.

  According to the twenty-first aspect of the present invention, in designing an image forming apparatus, the discomfort index derived by the sound quality evaluation formula (a) using the acoustic physical quantity obtained from the sound collection result of the sound emitted by the image forming apparatus. With respect to S, each part of the apparatus is designed so as to meet the condition (d) corresponding to the image forming speed, and it becomes possible to manufacture an image forming apparatus based on the design contents. Further, since the condition (d) varies depending on the image forming speed, even a low-speed machine or a high-speed machine has a plurality of operation modes and the like, and manufactures and provides an apparatus in which the image forming speed varies in each mode. Even if it is a case where it does, it becomes possible to obtain | require the discomfort index S for the acoustic physical quantity obtained from the operation sound using one sound quality evaluation formula (a), and the allowable value of this discomfort index S depends on speed It is possible to satisfy changing conditions.

According to a twenty-second aspect of the present invention, there is provided a method of manufacturing an image forming apparatus for forming an image on a recording paper, wherein sound is collected at a sound collecting position that is approximately 1 m away from an end surface of the image forming apparatus to be manufactured. A sound pressure level value, a loudness value, a sharpness value, a tonality value, an impulsiveness value of an acoustic physical quantity obtained from sound generated by the image forming apparatus when an image is formed on the recording paper, and an image on the recording paper. A design step of designing each part of the apparatus so that the discomfort index S calculated by the following equation (c) using the formation speed (v: mm / s) satisfies the following condition (d):
S = A × (sound pressure level value) + B × (loudness value) + C × (sharpness value)
+ D x (Tonality value) + E x (Impulsiveness value) + F
A = 0.0522715
B = 0.1580369
C = 0.41366496
D = 2.96777803
E = 1.291173747
F = −5.999889619
(C)
S ≦ 0.4248Ln (v) −2.4301 (d)
62.5 ≦ v ≦ 362
And a manufacturing step of manufacturing the image forming apparatus according to the design contents made in the designing step.

  According to the twenty-second aspect of the present invention, in designing an image forming apparatus, the discomfort index derived from the sound quality evaluation formula (c) using the acoustic physical quantity obtained from the sound collection result of the sound emitted by the image forming apparatus. With respect to S, each part of the apparatus is designed so as to meet the condition (d) corresponding to the image forming speed, and it becomes possible to manufacture an image forming apparatus based on the design contents. Further, since the condition (d) varies depending on the image forming speed, even a low-speed machine or a high-speed machine has a plurality of operation modes and the like, and manufactures and provides an apparatus in which the image forming speed varies in each mode. Even if it is a case where it does, it becomes possible to obtain | require the discomfort index S for the acoustic physical quantity obtained from the operation sound using one sound quality evaluation formula (c), and the allowable value of this discomfort index S depends on speed It is possible to satisfy changing conditions.

According to a twenty-third aspect of the present invention, there is provided a method of remodeling an image forming apparatus that has a plurality of image forming speeds / a plurality of operations of different modes and forms an image on recording paper, and is a target for remodeling. A sound collection step for collecting sound generated by the image forming apparatus when image formation is performed on the recording paper at a sound collection position approximately 1 m away from an end surface of the image forming apparatus, and sound collection in the sound collection step Using the sound pressure level value, the loudness value, the sharpness value, the tonality value, the impulsiveness value, and the output numerical value (ppm) of the recording paper per minute (A4 size lateral direction) obtained from the results, the following The discomfort index S calculated by the equation (a) includes a remodeling step for remodeling the device so as to satisfy the following condition (b).
S = A × (sound pressure level value) + B × (loudness value) + C × (sharpness value)
+ D x (Tonality value) + E x (Impulsiveness value) + F
0.037865 ≦ A ≦ 0.066678
0.126588 ≦ B ≦ 0.189486
0.367910 ≦ C ≦ 0.459389
2.532697 ≦ D ≦ 3.402664
1.132176 ≦ E ≦ 1.450574
−7.246314 ≦ F ≦ −4.7741981
(A)
S ≦ 0.4818Ln (ppm) −1.586 • (b)
14 ≦ ppm ≦ 65

  According to the twenty-third aspect of the present invention, the discomfort index S derived from the sound quality evaluation equation (a) using the acoustic physical quantity obtained from the sound collection result of the sound emitted from the image forming apparatus to be modified is 1 The configuration of each part of the apparatus is modified so as to meet the condition (b) corresponding to the output value of the recording paper per minute. Therefore, it becomes possible to manufacture and provide the user with an image forming apparatus that can reduce discomfort given to the user by the operation sound of the image forming apparatus. Further, since the condition (b) varies depending on the output value of the recording paper, the output value, that is, the low speed machine or the high speed machine has a plurality of operation modes and the image forming speed varies in each mode. Even when the device is modified, it is possible to obtain the discomfort index S from the sound physical quantity obtained from the device operation sound after the modification using one sound quality evaluation formula (a). It is possible to satisfy the condition that the allowable value varies depending on the speed.

According to a twenty-fourth aspect of the present invention, there is provided a method for remodeling an image forming apparatus for forming an image on recording paper, wherein the recording is performed at a sound collecting position approximately 1 m away from an end surface of the image forming apparatus to be remodeled. A sound collection step for collecting sound generated by the image forming apparatus when image formation is performed on paper, and a sound pressure level value, a loudness value, and a sharpness value of an acoustic physical quantity obtained from a sound collection result in the sound collection step , The tonality value, the impulsiveness value, and the output numerical value (ppm) of the recording paper (A4 size lateral direction) per minute, the discomfort index S calculated by the following equation (c) is as follows: A modification step for modifying the configuration of the apparatus so as to satisfy (b).
S = A × (sound pressure level value) + B × (loudness value) + C × (sharpness value)
+ D x (Tonality value) + E x (Impulsiveness value) + F
A = 0.0522715
B = 0.1580369
C = 0.41366496
D = 2.96777803
E = 1.291173747
F = −5.999889619
(C)
S ≦ 0.4818Ln (ppm) −1.586 • (b)
14 ≦ ppm ≦ 65

  According to the twenty-fourth aspect of the present invention, the discomfort index S derived by the sound quality evaluation formula (c) using the acoustic physical quantity obtained from the sound collection result of the sound emitted from the image forming apparatus to be modified is 1 The configuration of each part of the apparatus is modified so as to meet the condition (c) corresponding to the output value of the recording paper per minute. Therefore, it becomes possible to manufacture and provide the user with an image forming apparatus that can reduce discomfort given to the user by the operation sound of the image forming apparatus. Further, since the condition (b) varies depending on the output value of the recording paper, the output value, that is, the low speed machine or the high speed machine has a plurality of operation modes and the image forming speed varies in each mode. Even when the device is modified, the discomfort index S can be obtained from the acoustic physical quantity obtained from the device operation sound after the modification using one sound quality evaluation formula (a), and the allowable value of the discomfort index S It is possible to satisfy the condition that fluctuates depending on the speed.

According to a twenty-fifth aspect of the present invention, there is provided a method for remodeling an image forming apparatus for forming an image on a recording paper, wherein the recording paper is at a sound collecting position approximately 1 m away from an end surface of the image forming apparatus to be modified. A sound collecting step for collecting sound generated by the image forming apparatus when image formation is performed, and a sound pressure level value, a loudness value, a sharpness value of an acoustic physical quantity obtained from a sound collecting result in the sound collecting step, Using the tonality value, the impulsiveness value, and the image forming speed (v: mm / s) for the recording paper, the discomfort index S calculated by the following equation (a) satisfies the following condition (d): A modification step for modifying the configuration of the apparatus.
S = A × (sound pressure level value) + B × (loudness value) + C × (sharpness value)
+ D x (Tonality value) + E x (Impulsiveness value) + F
0.037865 ≦ A ≦ 0.066678
0.126588 ≦ B ≦ 0.189486
0.367910 ≦ C ≦ 0.459389
2.532697 ≦ D ≦ 3.402664
1.132176 ≦ E ≦ 1.450574
−7.246314 ≦ F ≦ −4.7741981
(A)
S ≦ 0.4248Ln (v) −2.4301 (d)
62.5 ≦ v ≦ 362

  In the invention according to claim 25, an image is obtained with respect to the discomfort index S derived by the sound quality evaluation formula (a) using the acoustic physical quantity obtained from the sound collection result of the sound emitted from the image forming apparatus to be modified. The configuration of each part of the apparatus is modified so as to meet the condition (d) corresponding to the forming speed. Therefore, it becomes possible to manufacture and provide the user with an image forming apparatus that can reduce discomfort given to the user by the operation sound of the image forming apparatus. In addition, since the condition (d) varies depending on the image forming speed, even if it is a low speed machine or a high speed machine, it has a plurality of operation modes and the like. Even in such a case, it is possible to obtain the discomfort index S using the single sound quality evaluation formula (a) from the parameter values obtained from the device operation sound after the modification, and the allowable value of the discomfort index S depends on the speed. It is possible to satisfy changing conditions.

According to a twenty-sixth aspect of the present invention, there is provided a method for remodeling an image forming apparatus for forming an image on a recording paper, wherein the recording paper is at a sound collecting position approximately 1 m away from an end surface of the image forming apparatus to be remodeled. A sound collecting step for collecting sound generated by the image forming apparatus when image formation is performed, and a sound pressure level value, a loudness value, a sharpness value of an acoustic physical quantity obtained from a sound collecting result in the sound collecting step, Using the tonality value, the impulsiveness value, and the image forming speed (v: mm / s) for the recording paper, the discomfort index S calculated by the following equation (c) satisfies the following condition (d): A modification step for modifying the configuration of the apparatus.
S = A × (sound pressure level value) + B × (loudness value) + C × (sharpness value)
+ D x (Tonality value) + E x (Impulsiveness value) + F
A = 0.0522715
B = 0.1580369
C = 0.41366496
D = 2.96777803
E = 1.291173747
F = −5.999889619
(C)
S ≦ 0.4248Ln (v) −2.4301 (d)
62.5 ≦ v ≦ 362

  According to the twenty-sixth aspect of the present invention, image formation is performed with respect to the discomfort index derived from the sound quality evaluation formula (c) using the acoustic physical quantity obtained from the sound collection result of the sound emitted from the image forming apparatus to be modified. The configuration of each part of the apparatus is modified so as to meet the condition (d) corresponding to the speed. Therefore, it becomes possible to manufacture and provide the user with an image forming apparatus that can reduce discomfort given to the user by the operation sound of the image forming apparatus. In addition, since the condition (d) varies depending on the image forming speed, even if it is a low speed machine or a high speed machine, it has a plurality of operation modes and the like. Even if it exists, it becomes possible to obtain the discomfort index S from the acoustic physical quantity obtained from the device operation sound after the modification using one sound quality evaluation formula (c), and the allowable value of the discomfort index S depends on the speed. It is possible to satisfy changing conditions.

上記式の導出に用いた心理音響パラメータ値の平均値を、上記式（ｅ）に代入するとともに、そのときのα＝０ と定義することにより、音の不快さの評価値を予測する音質評価式を導出し、導出した音質評価式を用いて音質評価を行うことを特徴とする。 According to a twenty-seventh aspect of the present invention, there is provided a method for evaluating a sound generated by an image forming apparatus that forms an image on a recording sheet at the time of image formation. A paired comparison method is used, and a multiple regression analysis is performed using the difference between the scores based on the evaluation as an objective variable and the difference between psychoacoustic parameter values as an explanatory variable. From the result, the following equation (e )

The sound quality evaluation for predicting the evaluation value of the discomfort of the sound by substituting the average value of the psychoacoustic parameter values used in the derivation of the above equation into the above equation (e) and defining α = 0 at that time An expression is derived, and sound quality evaluation is performed using the derived sound quality evaluation expression.

  In the invention according to claim 27, first, an expression relating to the relationship between the difference in sound scores and the difference in psychoacoustic parameter values is obtained, and then a sound quality evaluation expression for predicting the sound evaluation itself is derived from the expression. This makes it possible to derive a highly accurate sound quality evaluation formula without performing a relatively large number of experiments.

上記式の導出に用いた心理音響パラメータ値の平均値を、上記式（ｅ）に代入するとともに、そのときのα＝０ と定義することにより、音の不快さの評価値を予測する音質評価式を導出し、導出した音質評価式を用い、その音質評価式による音質評価が所定の条件を満たすよう装置各部を設計し、当該設計内容にしたがって画像形成装置を製造することを特徴とする。 According to a twenty-eighth aspect of the present invention, there is provided an image forming apparatus manufacturing method for forming an image on a recording paper, wherein the image forming apparatus evaluates a plurality of types of sounds generated during image formation by a paired comparison method. In addition, a multiple regression analysis is performed with the difference in the scores resulting from the evaluation as an objective variable and the difference in the psychoacoustic parameter values as an explanatory variable, and the following equation (e) regarding the difference in the evaluation of sound quality is derived from the result,

The sound quality evaluation for predicting the evaluation value of the discomfort of the sound by substituting the average value of the psychoacoustic parameter values used in the derivation of the above equation into the above equation (e) and defining α = 0 at that time It is characterized in that each part of the apparatus is designed so that the sound quality evaluation by the sound quality evaluation formula satisfies a predetermined condition using the derived sound quality evaluation formula, and the image forming apparatus is manufactured according to the design contents.

  In the invention according to claim 28, first, an expression relating to the relationship between the difference in sound scores and the difference in psychoacoustic parameter values is obtained, and then a sound quality evaluation expression for predicting the sound evaluation itself is derived from the expression. This makes it possible to derive a highly accurate sound quality evaluation formula without performing a relatively large number of experiments.

上記式の導出に用いた心理音響パラメータ値の平均値を、上記式（ｅ）に代入するとともに、そのときのα＝０と定義することにより、音の不快さの評価値を予測する音質評価式を導出し、この導出した音質評価式を用いて改造対象となる画像形成装置の発する音の音質評価を行い、さらに、かかる音質評価結果にしたがって改造対象となる前記画像形成装置の構成を改造することを特徴とする。 The invention according to claim 29 is a method for remodeling an image forming apparatus for forming an image on a recording paper, wherein the image forming apparatus evaluates a plurality of types of sounds generated during image formation by a paired comparison method. In addition, the multiple regression analysis was performed using the difference in the scores resulting from the evaluation as the objective variable and the difference in the psychoacoustic parameter values as the explanatory variable, and the following formula (e) regarding the difference in the evaluation of the sound quality was derived from the result. ,

The sound quality evaluation for predicting the evaluation value of sound discomfort by substituting the average value of the psychoacoustic parameter values used in the derivation of the above equation into the above equation (e) and defining α = 0 at that time The sound quality evaluation of the image forming apparatus to be modified is performed using the derived sound quality evaluation formula, and the configuration of the image forming apparatus to be modified is further modified according to the sound quality evaluation result. It is characterized by doing.

  In the invention according to claim 29, first, an expression relating to the relationship between the difference in sound scores and the difference in psychoacoustic parameter values is obtained, and then a sound quality evaluation expression for predicting the sound evaluation itself is derived from the expression. This makes it possible to derive a highly accurate sound quality evaluation formula without performing a relatively large number of experiments.

  The image forming apparatus according to the present invention (Claim 1) has a condition corresponding to the value of the image forming speed with respect to the discomfort index S derived by the sound quality evaluation formula using the acoustic physical quantity obtained from the sound emitted from the image forming apparatus. By configuring the image forming apparatus so as to match the above, it is possible to reduce discomfort given to the user by the sound generated by the image forming apparatus. Further, since the predetermined condition varies depending on the output value of the recording paper, the output value, that is, the low speed machine or the high speed machine has a plurality of operation modes, and the image forming speed varies in each mode. Even in a device, it is possible to obtain an uncomfortable index S using a single sound quality evaluation formula for an acoustic physical quantity obtained from the operation sound, and a condition under which an allowable value of the unpleasant index S varies depending on speed. By satisfying the above, it is possible to reduce the discomfort given to the user by the operation sound regardless of the mode.

  In addition, the image forming apparatus according to the present invention (Claim 2) uses the acoustic physical quantity obtained from the sound emitted by the image forming apparatus, and the discomfort index S derived by the sound quality evaluation formula (a) per minute. Since the image forming apparatus is configured to meet the condition (b) corresponding to the output value of the recording paper, it is possible to reduce discomfort given to the user by the sound generated by the image forming apparatus. Further, since the condition (b) varies depending on the output value of the recording paper, the output value, that is, the low speed machine or the high speed machine has a plurality of operation modes and the image forming speed varies in each mode. Even in the device, the discomfort index S can be obtained from the acoustic physical quantity obtained from the operation sound by using one sound quality evaluation formula (a), and the allowable value of the discomfort index S varies depending on the speed. Since the condition is satisfied, it is possible to reduce the discomfort that the operation sound gives to the user regardless of the mode.

  The image forming apparatus according to the present invention (Claim 3) records per minute with respect to the discomfort index derived by the sound quality evaluation formula (c) using the acoustic physical quantity obtained from the sound emitted by the image forming apparatus. Since the image forming apparatus is configured to match the condition (b) corresponding to the paper output numerical value, it is possible to reduce discomfort given to the user by the sound generated by the image forming apparatus. Further, since the condition (b) varies depending on the output value of the recording paper, the output value, that is, the low speed machine or the high speed machine has a plurality of operation modes and the image forming speed varies in each mode. Even in a device, the discomfort index S can be obtained from the acoustic physical quantity obtained from the operation sound using one sound quality evaluation formula (c), and the allowable value of the discomfort index S varies depending on the speed. Since the condition is satisfied, it is possible to reduce the discomfort that the operation sound gives to the user regardless of the mode.

  The image forming apparatus according to the present invention (Claim 4) has an image forming speed with respect to the discomfort index S derived by the sound quality evaluation formula (a) using the acoustic physical quantity obtained from the sound emitted by the image forming apparatus. Since the image forming apparatus is configured to meet the corresponding condition (d), it is possible to reduce the discomfort given to the user by the sound generated by the image forming apparatus.

  In addition, since the condition (d) varies depending on the image forming speed, the image forming apparatus has a plurality of operation modes and the like, and an image forming apparatus such as an apparatus in which the image forming speed varies in each mode, a low speed machine, a high speed machine, or the like is different. Even in such a case, the discomfort index S can be obtained from the acoustic physical quantity obtained from the operation sound by using one sound quality evaluation formula (a), and the allowable value of the discomfort index S varies depending on the speed. Since the condition is satisfied, it is possible to reduce the discomfort that the operation sound gives to the user regardless of the mode.

  Further, the image forming apparatus according to the present invention (Claim 5) has an image forming speed with respect to the discomfort index S derived by the sound quality evaluation formula (c) using the acoustic physical quantity obtained from the sound emitted from the image forming apparatus. Since the image forming apparatus is configured to meet the corresponding condition (d), it is possible to reduce the discomfort given to the user by the sound generated by the image forming apparatus.

  In addition, since the condition (b) varies depending on the image forming speed, the image forming apparatus has a plurality of operation modes and the like, and the image forming apparatuses such as an apparatus in which the image forming speed varies in each mode, a low speed machine, a high speed machine, and the like are different. Even in this case, the discomfort index S can be obtained from the acoustic physical quantity obtained from the operation sound using one sound quality evaluation formula (d), and the allowable value of the discomfort index S varies depending on the speed. Since the condition is satisfied, it is possible to reduce the discomfort that the operation sound gives to the user regardless of the mode.

  In addition, the image forming apparatus according to the present invention (Claim 6) has an effect that it is possible to reduce discomfort of the operation sound in any operation mode selected by the operation control means.

  Further, the image forming apparatus according to the present invention (claim 7) has the discomfort index S obtained from the result of sound collection at a position on the front side of the image forming apparatus that is likely to be normally located by the user of the image forming apparatus. On the other hand, since the above-described conditions are satisfied, there is an effect that it is possible to reduce discomfort given to the user by the operation sound of the image forming apparatus.

  In the image forming apparatus according to the present invention (claim 8), the discomfort index S is derived from the sound collected in the four directions of the image forming apparatus, and the average value satisfies the condition. Even if there is a user, there is an effect that the discomfort given to the user by the operation sound can be reduced on average.

  In the image forming apparatus according to the present invention (claim 9), the discomfort index S derived from the sound collected on at least one direction side of the image forming apparatus satisfies the condition, so On the other hand, there is an effect that the discomfort caused by the operation sound of the image forming apparatus can be reduced.

  Further, in the image forming apparatus according to the present invention (claim 10), the discomfort index S derived from the sound collected in all directions of the front, rear, left and right directions of the image forming apparatus satisfies the condition, so that the user No matter which direction it is, there is an effect that the discomfort that the operation sound of the image forming apparatus gives to the user can be reduced.

  In the image forming apparatus according to the present invention (claim 11), the sound reduction means can reduce the sound emitted by the image forming apparatus during image formation, and thereby the discomfort index derived from the sound generated by the image forming apparatus. There is an effect that S satisfies the condition and the discomfort given to the user by the sound generated by the image forming apparatus can be reduced.

  Further, in the image forming apparatus according to the present invention (claim 12), the vibration transmitted during the operation of the stepping motor is not directly transmitted to the bracket member, but is absorbed by the elastic body, so that the vibration transmitted to the bracket member is reduced, There is an effect that the sound generated due to this vibration can be reduced.

  The image forming apparatus according to the present invention (claim 13) drives the stepping motor at a step angle smaller than the step angle of the normal mechanically determined stepping motor by microstep driving the stepping motor. be able to. As a result, the rotor driving of the stepping motor becomes smooth, and the occurrence of vibrations is suppressed, so that the operation sound can be reduced.

  In the image forming apparatus according to the present invention (Claim 14), the Helmholtz resonator confines the sound component of the Helmholtz resonance frequency determined from the shape and the like in the cavity, that is, attenuates the sound component of the resonance frequency. Since it has a function, by installing a Helmholtz resonator having a resonance frequency corresponding to the main frequency component of the sound generated by the motor in the vicinity, the amount of leakage of the sound generated by the motor to the outside of the apparatus can be reduced.

  In the image forming apparatus according to the present invention (claim 15), when the charging means is charged to the image carrier, the image carrier vibrates due to the charging action, and sound is generated due to the vibration. However, the vibration generated in the image carrier can be suppressed by the damping member, and the generated sound can be reduced. Further, since the vibration damping member is disposed inside the image carrier, there is an effect that it is not necessary to prepare a new installation space or the like.

  In addition, the image forming apparatus according to the present invention (invention 16) is configured such that the bent portion of the flexible sheet in the guide member is in contact with the recording paper to be conveyed, so that the sound generated by the contact is reduced. be able to. That is, when the flexible sheet has a predetermined size, it is usually cut, but there are burrs or the like at the cut portion of the flexible sheet, and an irritating sound is generated when this portion comes into contact with the recording paper. On the other hand, in the present invention, the bent portion, not the cut portion, comes into contact with the recording paper as described above, so that an effect of reducing annoying sound can be achieved.

  In addition, the image forming apparatus according to the present invention (claim 17) uses a toner containing wax to provide a fixing member for improving the separation between the fixing member and the recording paper during the fixing process in image formation. On the other hand, there is no need to perform operations such as oil application. Therefore, there is an effect that it is possible to reduce the sound generated with the oil application operation.

  In the image forming apparatus according to the present invention (claim 18), only the electromagnetic clutch of the paper feed stage to be used is operated to reduce the metal impact sound, thereby reducing the impulsiveness value (impact sound value). Therefore, it is possible to reduce the generation of harsh sounds.

  The image forming apparatus manufacturing method according to the present invention (claim 19) is a sound quality evaluation formula using an acoustic physical quantity obtained from a sound collection result of sound generated by the image forming apparatus when designing the image forming apparatus. Each part of the apparatus is designed so as to meet the condition (b) corresponding to the output value of the recording paper per minute for the discomfort index S derived by a), and image formation based on the design contents The device is manufactured. Therefore, it is possible to produce an image forming apparatus that can reduce discomfort given to the user by the operation sound and provide the user with the effect.

  In addition, since the condition (b) varies depending on the output value of the recording paper, the output value, that is, a plurality of operation modes, etc. are provided, and an apparatus in which the image forming speed varies in each mode is manufactured and provided. Even if the image forming apparatus is manufactured and provided, such as a low speed machine or a high speed machine, the discomfort index is obtained by using the sound quality evaluation formula (a) to obtain the acoustic physical quantity obtained from the operation sound. S can be obtained, and since the allowable value of the discomfort index S satisfies a condition that varies depending on the speed, it is possible to reduce the discomfort that the operation sound gives to the user regardless of the mode. Play.

  The image forming apparatus manufacturing method according to the present invention (Claim 20) is a sound quality evaluation formula using an acoustic physical quantity obtained from a sound collection result of sound generated by the image forming apparatus when designing the image forming apparatus. Each part of the apparatus is designed so as to meet the condition (b) corresponding to the output value of the recording paper per minute for the discomfort index S derived by c), and image formation based on such design contents The device is manufactured. Therefore, it is possible to manufacture and provide the user with an image forming apparatus that can reduce the discomfort of the operation sound to the user. In addition, since the condition (b) varies depending on the output value of the recording paper, the output value, that is, a plurality of operation modes, etc. are provided, and an apparatus in which the image forming speed varies in each mode is manufactured and provided. Even if the image forming apparatus is manufactured and provided, such as a low speed machine or a high speed machine, the discomfort index is obtained by using the sound quality evaluation formula (c) for the acoustic physical quantity obtained from the operation sound. S can be obtained, and since the allowable value of the discomfort index S satisfies a condition that varies depending on the speed, it is possible to reduce the discomfort that the operation sound gives to the user regardless of the mode. Play.

  The image forming apparatus manufacturing method according to the present invention (claim 21) is a sound quality evaluation formula using acoustic physical quantities obtained from sound collection results of sound generated by the image forming apparatus when designing the image forming apparatus. Each part of the apparatus is designed so as to meet the condition (d) corresponding to the image forming speed with respect to the discomfort index S derived by a), and an image forming apparatus based on the design contents is manufactured. Therefore, an image forming apparatus that can reduce discomfort given to the user by the operation sound can be manufactured and provided to the user. In addition, since the condition (d) varies depending on the image forming speed, the apparatus has a plurality of operation modes and the like. Even in the case of manufacturing and providing a device with different image forming apparatuses such as a high-speed machine, the discomfort index S can be obtained by using one sound quality evaluation formula (a) for the acoustic physical quantity obtained from the operation sound. At the same time, since the allowable value of the discomfort index S satisfies a condition that fluctuates depending on the speed, it is possible to reduce the discomfort given to the user by the operating sound regardless of the mode.

  In addition, in the image forming apparatus manufacturing method according to the present invention (claim 22), when designing the image forming apparatus, the sound quality evaluation formula (using the acoustic physical quantity obtained from the sound collection result of the sound emitted by the image forming apparatus) Each part of the apparatus is designed so as to meet the condition (d) corresponding to the image forming speed with respect to the discomfort index S derived by c), and an image forming apparatus based on the design contents is manufactured. Therefore, it is possible to manufacture and provide the user with an image forming apparatus that can reduce the discomfort of the operation sound to the user. In addition, since the condition (d) varies depending on the image forming speed, the apparatus has a plurality of operation modes and the like. Even when an image forming apparatus such as a high-speed machine is manufactured and provided, the discomfort index S can be obtained by using one sound quality evaluation formula (c) for the acoustic physical quantity obtained from the operation sound. At the same time, since the allowable value of the discomfort index S satisfies a condition that fluctuates depending on the speed, it is possible to reduce the discomfort given to the user by the operating sound regardless of the mode.

  The image forming apparatus remodeling method according to the present invention (claim 23) is derived from the sound quality evaluation formula (a) using the acoustic physical quantity obtained from the sound collection result of the sound emitted by the image forming apparatus to be remodeled. The configuration of each part of the apparatus is modified so as to meet the condition (b) corresponding to the output value of the recording paper per minute for the discomfort index S. Therefore, the image forming apparatus that can reduce the discomfort given to the user by the operation sound of the image forming apparatus can be modified and provided to the user. Further, since the condition (b) varies depending on the output value of the recording paper, it has the output value, that is, a plurality of operation modes, etc., and the apparatus in which the image forming speed varies in each mode is modified. Even when the image forming apparatus is modified and provided, such as a low speed machine or a high speed machine, the discomfort index is obtained by using the single sound quality evaluation formula (a) for the acoustic physical quantity obtained from the modified apparatus operating sound. S can be obtained, and since the allowable value of the discomfort index S satisfies a condition that varies depending on the speed, it is possible to reduce the discomfort that the operation sound gives to the user regardless of the mode. Play.

  The image forming apparatus remodeling method according to the present invention (claim 24) is derived by the sound quality evaluation formula (c) using the acoustic physical quantity obtained from the sound collection result of the sound emitted from the image forming apparatus to be remodeled. The configuration of each part of the apparatus is modified so as to meet the condition (c) corresponding to the output value of the recording paper per minute for the discomfort index S. Therefore, the image forming apparatus that can reduce the discomfort given to the user by the operation sound of the image forming apparatus can be modified and provided to the user. Further, since the condition (b) varies depending on the output value of the recording paper, it has the output value, that is, a plurality of operation modes, etc., and the apparatus in which the image forming speed varies in each mode is modified. Even when the image forming apparatus is modified and provided, such as a low speed machine or a high speed machine, the discomfort index is obtained by using the single sound quality evaluation formula (a) for the acoustic physical quantity obtained from the modified apparatus operating sound. S can be obtained, and since the allowable value of the discomfort index S satisfies a condition that varies depending on the speed, it is possible to reduce the discomfort that the operation sound gives to the user regardless of the mode. Play.

  The image forming apparatus remodeling method according to the present invention (claim 25) is derived by the sound quality evaluation formula (a) using the acoustic physical quantity obtained from the sound collection result of the sound emitted by the image forming apparatus to be remodeled. For the discomfort index S, the configuration of each part of the apparatus is modified so as to meet the condition (d) corresponding to the image forming speed. Therefore, the image forming apparatus that can reduce the discomfort given to the user by the operation sound of the image forming apparatus can be modified and provided to the user. In addition, since the condition (d) varies depending on the image forming speed, it has a plurality of operation modes and the like, and it is a case where a device in which the image forming speed fluctuates in each mode is modified, a low speed machine, a high speed machine, etc. Even if the image forming apparatus is provided by modifying a different apparatus, the discomfort index S can be obtained by using one sound quality evaluation formula (a) for the acoustic physical quantity obtained from the apparatus operating sound after the modification. At the same time, since the allowable value of the discomfort index S satisfies a condition that fluctuates depending on the speed, it is possible to reduce the discomfort given to the user by the operating sound regardless of the mode.

  The image forming apparatus remodeling method according to the present invention (claim 26) is derived from the sound quality evaluation formula (c) using the acoustic physical quantity obtained from the sound collection result of the sound emitted by the image forming apparatus to be remodeled. For the discomfort index S, the configuration of each part of the apparatus is modified so as to meet the condition (d) corresponding to the image forming speed. Therefore, the image forming apparatus that can reduce the discomfort given to the user by the operation sound of the image forming apparatus can be modified and provided to the user. In addition, since the condition (d) varies depending on the image forming speed, it has a plurality of operation modes and the like, and it is a case where a device in which the image forming speed fluctuates in each mode is modified, a low speed machine, a high speed machine, etc. Even if the image forming apparatus is provided by modifying a different apparatus, the discomfort index S can be obtained by using one sound quality evaluation formula (c) for the acoustic physical quantity obtained from the apparatus operating sound after the modification. At the same time, since the allowable value of the discomfort index S satisfies a condition that fluctuates depending on the speed, it is possible to reduce the discomfort given to the user by the operating sound regardless of the mode.

  The sound quality evaluation method according to the present invention (Claim 27) first obtains an expression relating to the relationship between the difference in the score of the sound and the difference in the psychoacoustic parameter value, and then predicts the sound evaluation itself from the expression. Since the evaluation formula is derived, it is possible to derive a high-accuracy sound quality evaluation formula without performing a relatively large number of experiments, and as a result, the work relating to the sound quality evaluation is simplified.

  In the image forming apparatus manufacturing method according to the present invention (claim 28), first, an expression relating to the relationship between the difference in the score of the sound and the difference in the psychoacoustic parameter value is obtained, and then the sound evaluation itself is calculated from the expression. Since the sound quality evaluation formula to be predicted is derived, a highly accurate sound quality evaluation formula can be derived without performing a relatively large number of experiments, and as a result, an effect of simplifying work relating to sound quality evaluation can be obtained. An image forming apparatus is manufactured in which each part of the apparatus is designed so that the sound quality evaluation based on the sound quality evaluation formula thus obtained satisfies a predetermined condition, that is, an image forming apparatus that hardly generates unpleasant sound is provided. There is an effect that can be done.

  In the image forming apparatus remodeling method according to the present invention (claim 29), first, an expression relating to a relationship between a difference in sound scores and a difference in psychoacoustic parameter values is obtained, and then the sound evaluation itself is calculated from the expression. Since the sound quality evaluation formula to be predicted is derived, a highly accurate sound quality evaluation formula can be derived without performing a relatively large number of experiments, and as a result, an effect of simplifying work relating to sound quality evaluation can be obtained. Then, the apparatus configuration is modified based on the sound quality evaluation of the sound generated by the image forming apparatus using the sound quality evaluation formula thus obtained. Therefore, it is possible to provide an image forming apparatus that can obtain a good sound quality evaluation, that is, can hardly generate unpleasant sounds.

  Exemplary embodiments of an image forming apparatus, an image forming apparatus manufacturing method, an image forming apparatus remodeling method, and a sound quality evaluation method according to the present invention will be described below in detail with reference to the accompanying drawings.

  The present invention performs sound quality evaluation of a plurality of image forming apparatuses and image forming apparatuses having a plurality of image forming modes for each apparatus and mode, comprehensively analyzes the results to derive a single sound quality evaluation formula, Thus, an image forming apparatus having an acoustic physical quantity (or described as a psychoacoustic parameter value) is lowered and the sound quality evaluation value or less allowed by the user is provided. In other words, if an image quality improvement device is provided so that the image quality is lower than the permissible value of the sound quality corresponding to each image forming device, any mode can be used regardless of which mode is used. Even if it is used, the problem of unpleasant noise related to the image forming apparatus is solved. Hereinafter, the configuration of the apparatus, sound collection conditions and analysis results, sound quality evaluation, measures for reducing unpleasant noise, and the like will be specifically described.

(Embodiment)
A. Configuration of Image Forming Apparatus There are various forms of image forming apparatuses with different image forming speeds, structures, and apparatus sizes, and typical configurations are shown below.

A-1. FIG. 1 is an explanatory diagram showing an example of the overall configuration of an image forming apparatus (apparatus having a plurality of modes) according to an embodiment of the present invention. The present invention is a remodeling method for evaluating noise generated by such a general image forming apparatus and taking measures for reducing discomfort given to humans by the noise according to the evaluation. Prior to the description, the configuration of a general image forming apparatus will be described.

  The image forming apparatus shown in FIG. 1 is a digital color printer that employs an electrophotographic system, and includes an optical unit 1, a photoreceptor unit 3, a developing unit 4, a transfer unit 5, a fixing unit 46, and a paper feeding unit. 110.

  At the time of image formation, recording paper (printing paper and OHP sheet (film-like sheet for an overhead projector)) accommodated in a paper feeding unit 110 disposed at the bottom of the image forming apparatus is included. Is conveyed along a predetermined conveyance path that rises from the lower right side to the upper left side of the figure. The sheet thus transported is fed out from the sheet feeding unit 110 and is conveyed along the oblique conveyance path from the lower right side to the upper left side of the drawing to the upper side of the sheet feeding unit 110. During this time, the sheet is similarly passed between the four photosensitive units 3, the developing unit 4 and the transfer unit 5 arranged side by side along the conveyance path, and a predetermined image is transferred. The sheet on which the image has been transferred is transported to a fixing unit 46 that is arranged on the upper left side of the photosensitive unit 3, the developing unit 4, and the transfer unit 5, and the transferred image is fixed on the recording sheet by the fixing unit 46. .

  As shown in FIG. 2, the optical unit 1 is a unit that extends along a sheet conveyance path that is an oblique direction such as the lower right to the upper left direction of FIG. 2, and includes a housing 11 disposed along that direction. Have. Laser diodes (LD) 17 (Bk: black), 18 (C: cyan), 19 (M: magenta), and 20 (Y: yellow) for each of four colors are attached to the upper portion of the housing 11.

  The housing 11 includes a polygon mirror motor 2 for scanning in the main scanning line direction, two-layer f / θ lenses 21 and 22 for dot position correction, and a long WTL lens 23 for surface tilt correction. , 24, 25, 26, a cylinder lens (not shown) for correcting the laser beam diameter is attached.

  The polygon mirror motor 2 is integrally formed with two upper and lower six-sided mirrors 27, and the polygon mirror 27 is irradiated with laser light emitted from the LDs 17, 18, 19, and 20.

  The LDs 17, 18, 19, and 20 corresponding to the respective colors emit light in accordance with the conveyance timing of the paper, and the light (indicated by bold lines in the drawing) is a cylinder lens, a polygon mirror 27, two-layer f / θ lenses 21, 22, The photosensitive drum 28 of each color is irradiated through the long WTL lenses 23, 24, 25, and 26.

  As the LD unit 17 corresponding to black, it is preferable to adopt a two-beam type. That is, by adopting a two-beam LD, two beams can be written simultaneously when forming a monochrome image, and rapid writing can be performed while suppressing the number of rotations of the polygon mirror motor 2. By reducing the rotation speed of the polygon mirror motor 2 in this way, it is possible to obtain an effect of suppressing noise and an effect of extending the life of the motor. For example, when printing in the color mode, the rotation speed of the polygon mirror 27 is 29528 rpm (revolution per minute) and the printing speed is 28 ppm (pages per minute). However, during monochrome printing, the rotation speed of the polygon mirror 27 is 21850 rpm. Despite being small, the printing speed is 38 ppm.

  Next, returning to FIG. 1, the configuration of the photosensitive unit 3, the developing unit 4 and the transfer unit 5 in the image forming apparatus will be described. As shown in the figure, this image forming apparatus employs a four-drum tandem image forming method, and this method improves the printing speed in the full-color printing mode and the monochrome printing mode. . Further, as described above, the photoconductor unit 3, the developing unit 4, and the transfer unit 5 are disposed obliquely, thereby reducing the installation space, thereby reducing the size of the entire apparatus.

  The photosensitive unit 3 and the developing unit 4 are independent units for each color. That is, the photosensitive unit 3 and developing unit 4 for magenta (M), the photosensitive unit 3 and developing unit 4 for cyan (C), the photosensitive unit 3 and developing unit 4 for yellow (Y), and black (Bk). 1) and the developing unit 4 are arranged in the above order from the lower right side to the upper left side in FIG. The M, C, and Y photoconductor units 3 except for Bk have exactly the same configuration, so that any new unit (M, C, Y) may be used. Good.

  The transfer unit 5 is a unit extending along the oblique direction below the photosensitive unit 3 and the developing unit 4 arranged in the oblique direction in the above-described order, and is disposed along the oblique direction. Yes. The transfer unit 5 includes a plurality of rollers and an endless transfer belt 29 wound around the rollers. When the roller is rotated by a motor (not shown), the transfer belt 29 is rotated counterclockwise in the figure, and the sheet fed from the paper feeding unit 110 is placed on the transfer belt 29 from the lower right side of the figure. It is conveyed to the upper left. In addition, a P sensor 6 used for toner density detection is disposed on the downstream side in the transport direction of the transfer unit 5 (upper left in the drawing). The P sensor 6 optically detects the density of the P sensor pattern formed on the transfer belt 29, and the detection result is used for control.

  Here, sectional views of the photosensitive unit 3 and the developing unit 4 corresponding to the colors shown in FIG. 3 are shown. As shown in the figure, the photoreceptor unit 3 has a photoreceptor drum 28 (for example, an outer diameter φ30). The photosensitive drum 28 has a hollow cylindrical shape, and is configured to be rotated clockwise in the drawing by a driving mechanism described later.

  A charging roller 36 (for example, an outer diameter φ11) is disposed on the upper side of the photosensitive drum 28. The surface of the charging roller 36 is disposed at a position separated from the surface of the photosensitive drum 28 by about 0.05 mm. The charging roller 36 is rotated in the opposite direction to the photosensitive drum 28, that is, counterclockwise in the drawing, and applies a uniform charge on the surface of the photosensitive drum 28.

  A cleaning brush 37 is disposed above the charging roller 36. A cleaning brush 39 and a counter blade 38 are disposed on the upper left side of the photosensitive drum 28, and cleaning for removing residual toner and the like on the surface of the photosensitive drum 28 is performed by these.

  A waste toner collection coil 40 is disposed on the left side of the cleaning brush 39, and the waste toner collected by the waste toner collection coil 40 is conveyed to the waste toner bolt 16 shown in FIG. ing.

  Next, the developing unit 4 adopts a dry two-component magnetic brush developing method, and includes a developing roller 30, a developing doctor 31, a conveying screw left 32, a conveying screw right 33, a toner concentration sensor 34, Agent cartridge 35.

  Next, the drive mechanism of the photoreceptor unit 3 will be described with reference to FIG. The photoconductor unit 3 is provided for each color, and there are four units. Three photoconductor units 3 for M, C, and Y (for color), and a photoconductor unit 3 for Bk Are driven by separate drive mechanisms. That is, the color photoconductor unit 3 is driven by the color drum drive motor 41 as a drive source and the gears 43 and 44 and the joint 45 that transmit this drive force.

  On the other hand, the black photoconductor unit 3 is driven by another gear 44 and a joint 45 which use another black drum drive motor 42 as a drive source and transmit this drive force. Accordingly, during color mode printing, only the color drum drive motor 41 operates and the black drum drive motor 42 stops. On the other hand, during monochrome mode printing, only the black drum drive motor 42 operates and the color drum drive motor 41 stops. The color drum drive motor 41 and the black drum drive motor 42 are stepping motors.

  As shown in FIGS. 5 and 6, the fixing unit 46 employs a belt fixing system, and the belt has a smaller heat capacity than the fixing roller. There are merits such as shortening the warm-up time and lowering the roller set temperature during standby than the method used.

  The fixing unit 46 heats and pressurizes the sheet on which the image has been transferred, and fixes the toner image on the sheet. The fixing unit 46 includes a fixing belt 13 and an oil application unit 47. In the oil application unit 47, the gel oozes out from the oil and is supplied from the application felt 48 to the application roller 49. A small amount of silicone oil is applied to the fixing belt 13 while the application roller 49 rotates.

  By applying oil to the fixing belt 13 in this way, the fixing belt 13 and the paper are easily peeled off easily. That is, the releasability of the surface of the fixing belt 13 is improved. The application operation by the oil application unit 47 is performed every time one sheet is conveyed, and oil application is performed each time one sheet is conveyed by a mechanism having a solenoid or a spring (not shown). The unit 47 is driven and brought into contact with the fixing belt 13. On the other hand, when one sheet of paper passes, the oil application unit 47 is separated from the fixing belt 13 by the above mechanism.

  Further, as shown in FIG. 5, a cleaning roller 50 is provided on the upstream side of the fixing belt 13 in the sheet conveying direction, and the cleaning roller 50 adsorbs dirt on the fixing belt 13, thereby performing belt cleaning. This prevents the image of the paper from being stained due to the contamination of the fixing belt 13.

  The above is the configuration of the fixing unit 46, and the sheet that has passed through the fixing unit 46 is conveyed to the main body tray 510 shown in FIG.

  Next, the configuration of the paper feeding unit 110 will be described with reference to FIG. The sheet feeding unit 110 has three trays, a first tray 9, a second tray 10, and a manual sheet feeding tray 8. Each of these trays employs an FRR (feed reverse roller paper feed method: friction separation paper feed method) as a method of feeding out the paper stored in the tray. This FRR paper feed method feed mechanism uses a paper feed roller that is driven to rotate in the paper feed direction in order to separate the paper fed from the paper bundle stacked in the paper feed tray one by one. The reverse roller is brought into contact.

  In this configuration, the reverse roller is given a weak torque in the opposite direction to the paper feed roller via the torque limiter, so that it is in contact with the paper feed roller or a sheet of paper is between the two rollers. In the state where the sheet enters the roller, the sheet rotates with the sheet feeding roller. On the other hand, when the sheet is separated from the sheet feeding roller or when two or more sheets enter between the rollers, the sheet rotates in the reverse direction. For this reason, when the multi-feed paper enters, the paper in contact with the reversing roller is returned to the downstream side in the paper feeding direction, and multi-feed is prevented.

  The sheets stored in the first tray 9 are separated by the first sheet feeding unit 51 and sent out from the first tray 9. Then, the fed sheet is transported by the relay roller 53 and reaches the transport roller 55. Here, the sheet is conveyed toward the upper left registration roller 7 while being turned by the conveyance roller 55.

  The conveyed sheet hits the resist roller 7 that has stopped, and the skew of the sheet is corrected (skew correction). Then, timing adjustment with the image forming process by the photoconductor unit 3 or the like is performed, a registration clutch (not shown) is connected at a predetermined timing, the registration roller 77 is driven, and the sheet is conveyed toward the transfer unit. Thereafter, the sheet is conveyed by the transfer belt 29 as described above, and processing such as predetermined image transfer is executed.

  Note that the paper stored in the second tray 10 is transported toward the transport roller 55 by the second paper feed unit 52 and the relay roller 54, and the subsequent operation is the paper stored in the first tray 9. It is the same. Further, the paper set on the manual feed tray 8 is transported toward the registration roller 7 by the paper feed unit 56, and the subsequent processing is the same as the paper transport from the first tray 9.

  Next, a configuration for driving the first paper feed unit 51 and the second paper feed unit that feed paper from the first tray 9 and the second tray 10 as described above will be described. As shown in FIG. 8, both these units are driven by a single stepping motor 56, and the driving force is transmitted to each unit via a first paper feed clutch 57 and a second paper feed clutch 58. Is called. That is, when the paper is sent out from the first tray 9, only the first paper feed clutch 57 is connected to transmit the drive, and when the paper is sent out from the second tray 10, only the second paper feed clutch 58 is connected. It becomes a state.

  As described above, the image forming apparatus includes the color photoconductor unit 3 and the like, and can perform color printing as well as monochrome printing. More specifically, as shown in Table 1, the printer has four printing modes such as “monochrome mode”, “color mode [1]”, “color mode [2]”, and “OHP / thick paper mode”. When the user selects a mode by operating the operation unit or the like, a control unit (operation control unit) of the image forming apparatus (not shown) controls each unit according to the selection and operates each unit in the operation mode. . In this image forming apparatus, three types of processing speeds (182.5 mm / s = 38 ppm, 125.0 mm / s = 28 ppm, 62.5 mm / s = 14 ppm) are selected depending on the mode selected by the user from the control unit. It is supposed to switch to.

  In other words, the rotational speeds of the motors such as the stepping motor 56, the black drum driving motor 42, and the color drum driving motor 41 are controlled to change according to the selected operation mode. In this specification, “ppm” is the number of output sheets per minute of A4 landscape paper.

  Here, in the high-resolution “color mode [2]” and “OHP / thick paper mode”, the printing speed (image forming speed) is 14 ppm, whereas in the “monochrome mode”, the printing speed is 38 ppm. There is a speed difference close to twice. In order to realize such a large speed difference with a single motor, this image forming apparatus employs a stepping motor as a drive source for a paper transport mechanism system and the like.

A-2. Configuration of Desktop (Desktop) Image Forming Apparatus FIG. 51 is an explanatory diagram showing a configuration example of the image forming apparatus (desktop) according to the embodiment of the present invention. The image forming apparatus is a digital monochrome printer that employs an electrophotographic system, and operates in a single mode (monochrome print only).

  In the figure, reference numeral 301 denotes a photosensitive drum on which an electrostatic latent image and a toner image are formed, reference numeral 302 denotes a transfer roller for transferring the toner image formed on the photosensitive drum 301 onto a recording sheet, and reference numeral 303 denotes a photosensitive drum. A process cartridge for forming a toner image on the body drum 301. Reference numeral 304 denotes a main body feed tray for feeding out the recording paper by 301 sheets. Reference numeral 305 denotes a bank feed for feeding out the recording paper one by one in the same manner as the main body feed tray 304. A paper tray, reference numeral 306 is a manual feed tray for feeding paper by inserting a sheet of recording paper, reference numeral 307 is a fixing unit for fixing the toner image transferred to the recording paper by the action of heat and pressure, and reference numeral 308 is photosensitive. A writing unit for writing an image on the body drum 301. Reference numeral 309 denotes a paper discharge tray for discharging the recording paper after fixing. Reference numeral 310 denotes a recording paper. Reference numeral 311 denotes a registration roller that is activated / stopped so as to align with the toner image on the photosensitive drum 301, and reference numeral 312 denotes a paper discharge roller that conveys the recording paper to the paper discharge tray 309. Yes.

  In the image forming apparatus shown in FIG. 51, a sheet feeding conveyance system such as a main body sheet feeding tray 304, a bank sheet feeding tray 305, a manual feed tray 306, a sheet feeding roller 310, and a registration roller 311 is provided. After the image is transferred from the paper feed conveyance system through the image forming side of the process cartridge 303, the image is discharged to the paper discharge tray 309 through the fixing unit 307 and the paper discharge roller 312.

  A writing unit 308 including an LD unit, a polygon mirror, an f · θ lens (all not shown), and the like are disposed above the process cartridge 303. In addition, although not shown, a drive transmission system including a drive motor, a solenoid, and a clutch (mechanical clutch, electromagnetic clutch) for rotationally driving the photosensitive drum 301 and each roller is provided. In the image forming apparatus configured as described above, during the image formation, driving sound of the drive motor and the drive transmission system, operating sound by the solenoid clutch, recording paper feeding / conveying sound, charging sound and the like are radiated.

  FIG. 52 is an explanatory diagram showing a configuration example of the process cartridge 303 in FIG. The process cartridge 303 includes a charging roller 321 as a charging unit, a developing roller 322 as a developing unit, a cleaning blade 323 as a cleaning unit, an agitator 325 that stirs toner 324 and sends it to the developing roller 322, and a stirring shaft 326. And a developing blade 327. The charging roller 321 includes a cored bar 321a and a charging unit 321b.

  Around the photosensitive drum 301 as an image carrier, a charging roller 321, a developing roller 322, and a cleaning blade 323 are arranged under predetermined conditions. The toner 324 in the process cartridge 303 is stirred by the agitator 325 and the stirring shaft 326 and is conveyed to the developing roller 322. The toner 324 attached to the roller surface by the magnetic force in the developing roller 322 is negatively charged by frictional charging when passing through the developing blade 327. The negatively charged toner moves to the photosensitive drum 301 by the bias voltage and adheres to the electrostatic latent image.

  When the recording paper sent by the registration roller 311 passes between the photosensitive drum 301 and the transfer roller 302, the toner on the photosensitive drum 301 is transferred to the recording paper by the positive charge from the transfer roller 302. The toner remaining on the photosensitive drum 301 is scraped off by the cleaning blade 323 and is collected as waste toner in a tank above the cleaning blade 323. The parts other than the transfer roller 302 are integrated as a process cartridge 303 so that the user can replace it.

  FIG. 53 is an explanatory diagram showing the configuration of the charging roller 321 in FIG. As shown in FIGS. 52 and 53, the charging roller 321 is charged so that the surface of the photoconductive drum 301 is uniformly primary charged by being driven by a frictional force while always contacting the photoconductive drum 301 at a predetermined pressure. It is a member. As shown in FIG. 52, the charging roller 321 includes a cored bar 321a serving as a rotation shaft and a charging unit 321b formed concentrically around the cored bar 321a.

  When the charging roller 321 is charged, an AC voltage is superimposed on the DC voltage on the cored bar portion 321a via the electrode terminal 331, the charging roller pressure spring 332, and the conductive bearing 333 from a high voltage power source. The applied bias voltage is applied, and the charging roller 321 uniformly charges the photosensitive drum 301 to the same voltage as the DC component of the bias voltage. The AC component of the bias voltage functions to uniformly charge the photosensitive drum 301 by the charging roller 321 uniformly.

  By the way, when the photosensitive drum 301 is contact-charged by the charging roller 321, an attractive force and a repulsive force act alternately between the surfaces of the charging roller 321 and the photosensitive drum 301 due to the AC component of the bias voltage, and the charging roller 321. Causes vibration. This vibration of the charging roller 321 causes an irritating vibration sound (charging sound) having a high frequency in the charging roller 321 itself, and is also transmitted to the photosensitive drum 30 side to vibrate the photosensitive drum 301 and generate noise. Let

A-3. Configuration of Medium-Speed Image Forming Apparatus FIG. 54 is a front view showing an outline of a medium-speed digital copying machine as an example of the image forming apparatus. 54, the image forming apparatus mainly includes a main body 401 and a paper supply bank unit 402 capable of two-stage paper supply. Since the main body 401 is provided with a two-stage paper feed tray, the function of the image forming apparatus can be exhibited only by the main body 401 without the paper feed bank unit 402. Further, instead of the paper supply bank unit 402, an inexpensive supply storage table (not shown) having the same outer shape can be attached. The conveyance route indicated by the solid line arrow in FIG. 54 is a paper conveyance route at the time of image formation when paper is fed from the first tray 410 of the main body 401. When paper is fed from the second tray 411 of the main body 401 and the first tray 412 and the second tray 413 of the paper feed bank unit 402, the paper transport path is indicated by a broken line. Specifically, it joins the same path as the first tray 410 of the main body 401.

  Inside the main body 401, a charging roller 407, a writing system optical unit 404, a developing roller 408, a transfer roller 409, and the like arranged around a drum-shaped photoconductor 406 are arranged. A unit 403, a registration roller pair 416, a toner bottle 421, a fixing device 417, a paper discharge roller pair 419, and the like are arranged.

  Next, the operation of the image forming apparatus will be described. First, document data is read by the reading system optical unit 403 and converted into a digital electric signal. This digital electrical signal is subjected to image processing and sent to the writing optical unit 404. A light beam 405 based on the digital signal is emitted from the writing system optical unit 404 and irradiated onto the photoconductor 406. The photosensitive member 406 is driven to rotate counterclockwise in FIG. 54, the surface thereof is uniformly charged by the charging roller 407, and the original image is written on the charging surface by the writing system optical unit 404 as described above. As a result, an electrostatic latent image is formed on the photosensitive member 406, and this latent image is visualized as a toner image by the developing roller 408. Toner is supplied from a toner bottle 421 to a developing unit including the developing roller 408.

  On the other hand, a paper supply operation will be described using an example in which paper is fed from the first tray 410 of the main body 401. Only one sheet is separated from the first-stage tray 410 in which the sheets are stacked and stacked by the sheet feeding roller 414. The separated sheet of paper is turned tightly while being assisted by the conveyance auxiliary roller 415, and is directed upward to abut against the temporarily stopped registration roller pair 416, skew correction is performed, and the registration clutch After the registration is adjusted at the timing of restart by turning on, it goes to the image forming section.

  An image formed of toner on the photoconductor 406 is transferred to the paper when the paper passes between the photoconductor 406 and the transfer roller 409. Thereafter, the toner is conveyed to the fixing device 417, and the toner is fixed on the paper by the fixing roller pair 418 of the fixing device 417, and is discharged to the paper discharge tray 420 by the paper discharge roller pair 419. The image forming speed of the image forming apparatus according to the above embodiment is, for example, about 122 mm / s, and 27 images can be formed on the side of A4 in one minute.

A-4. Configuration of Large (Console Type) Image Forming Apparatus FIG. 55 is an explanatory diagram showing a configuration example of the image forming apparatus (console type) according to the embodiment of the present invention. That is, the overall height is designed to be used by installing on the floor surface, and the whole is the upper part (ADF (automatic document feeder) 510, scanner 520, writing unit 530, image forming engine 540) 500, lower part (bank). A console type digital MFP (multi-function printer) composed of a paper feed unit 570) is shown. In other words, there may be provided a normal copy function, a printer function according to an instruction from a host such as a personal computer, and a facsimile function.

  This type of image forming apparatus is generally a high speed machine. The upper part 500 includes an optical unit in which optical elements (scanner 520 and writing unit 530) are housed in a casing, an image forming engine 540 positioned below the optical unit, and an ADF 510 disposed on the upper part of the casing.

  In FIG. 55, reference numeral 501 denotes a photosensitive drum as an image carrier on which an electrostatic latent image is formed, reference numeral 502 denotes a charging charger, reference numeral 503 denotes a developing unit, reference numeral 504 denotes a transfer / separation charger, reference numeral 505 denotes a cleaning unit, Reference numeral 506 is a fixing unit, reference numeral 507 is a registration roller, reference numeral 511 is a document table, reference numeral 512 is a contact glass, reference numeral 513 is an exposure lamp, reference numeral 514 is a first mirror, reference numeral 515 is a second mirror, and reference numeral 516 is a third mirror. , 517 is an imaging lens, 518 is a CCD (Charge Coupled Device), 519 is a mirror, and 590 is a caster with a lock function.

  That is, the scanner 520 includes a contact glass 512 on which a document is placed and a scanning optical system. The scanning optical system includes a first carriage on which an exposure lamp 513 and a first mirror 514 are mounted, a second carriage that holds the second mirror 515 and the third mirror 516, an imaging lens 517, and a CCD 518. Yes. A first carriage that is driven by a stepping motor and moves at a constant speed when reading an original is provided, and a second carriage that is driven at a speed half that of the first carriage.

  A document (not shown) on the contact glass 512 is optically scanned by the first carriage and the second carriage, and the reflected light obtained there is an exposure lamp 513, a first mirror 514, a second mirror 515, a third mirror. An image is formed on the CCD 519 via the mirror 516 and the imaging lens 517, and photoelectrically converted.

  The writing unit 530 includes a laser output unit, an f · θ lens, a mirror (all not shown), and the like. The laser output unit is provided with a laser diode and a polygon mirror which are laser light sources.

  The image signal output from the image processing unit is converted into a laser beam having an intensity corresponding to the image signal by the writing unit 530, and is shaped into a light beam having a fixed shape by a collimating lens, an aperture, and a cylinder lens, and then converted into a polygon mirror. Irradiated and output. The laser beam output from the writing unit 530 is applied to the photosensitive drum 501 through the mirror 519. The laser beam that has passed through the f · θ lens is applied to a beam sensor (not shown) that generates a main scanning synchronization detection signal arranged outside the image area.

  An ADF (automatic document feeder) 510 conveys documents set on a document table 511 one by one to the contact glass 512, and discharges them after reading. That is, the document is set on the document table 511 and the width direction is aligned by the side guide. The documents on the document table 511 are fed one by one from the bottom document by a feed roller, and are fed onto the contact glass 501 by the transport belt 553. After the document on the contact glass 512 is read, the document is discharged onto the discharge tray by the transport belt and the discharge roller.

  The recording sheets stacked on the first tray 571, the second tray 572, the third tray 573, and the fourth tray 574 of the bank sheet feeding unit 570 are the first sheet feeder 575, the second sheet feeder 576, and the second sheet feeder 576, respectively. The paper is fed by a third paper feeding device 577 and a fourth paper feeding device 578 and further conveyed by a bank vertical conveyance unit 579 and a main body vertical conveyance unit 580. When the leading edge of the recording paper is detected by a registration sensor (not shown), the recording paper is conveyed for a predetermined time, and then temporarily stops at the nip portion of the registration roller 507 and enters a standby state.

  The waiting recording sheet is sent to the photosensitive drum 501 side in accordance with the timing of the image valid signal, and is brought into close contact with the photosensitive drum 501 when the transfer / separation charger 504 is turned on, and the image is transferred. Further, the recording paper is separated from the photosensitive drum 501 by separating from the photosensitive drum 501. The recording paper onto which the toner image has been transferred is conveyed by a conveying device, fixed by the heat and pressure action of a fixing unit 506 having a fixing roller and a pressure roller, and discharged to the outside by a paper discharge roller 581. .

  As described above, the image formation on the photosensitive drum 501 is performed by irradiating the laser beam with the electric charge charged on the photosensitive drum 501 by the charging charger 502, and forming the electrostatic latent image by the developing unit 503. A toner image is formed on the drum 501.

  When duplex printing is performed using the duplex unit 585, the recording paper after fixing is guided to the duplex conveyance path 586 by the switching claw 528, and passes through the feed roller 532 and the separation roller 533 and is collected on the duplex tray. The recording paper accumulated in the tray is brought into contact with the feed roller when the tray is raised, and is fed to the main body vertical conveyance unit 580 when the feed roller rotates, and is re-fed to the registration roller 507 and then back to the back surface. Is printed.

  When performing reverse paper discharge, the switching claw 567 guides the recording paper in the direction of the special reverse tray 564, and when the rear end of the recording paper passes through the reverse detection sensor 568, the transport roller 569 reverses and the paper discharge tray direction And discharge the paper to a preset tray.

B. Next, a method for evaluating the sound quality of noise radiated from the image forming apparatus configured as described above will be described. That is, the sound quality evaluation according to the present invention is a remodeling method that makes a sound quality evaluation technique that is a measure (design) for reducing unpleasant feeling given to a person by the noise and a manufacturing method based on the sound quality evaluation. Hereinafter, a method for evaluating noise generated by the image forming apparatus configured as described above during image formation will be described.

  The present inventor decided to perform sound quality evaluation based on the following idea. First, in order to objectively evaluate the degree of discomfort such as mechanical sound, a standard for measuring discomfort is required. One method for creating such a standard is a method paired comparison. The paired comparison method creates two stimulus pairs for a stimulus that is difficult to be absolutely evaluated, such as a sound emitted from an image forming apparatus. Then, all the combinations of stimuli to be evaluated are paired, the difference between the scores is obtained, and a relative average score is given for each stimulus. This method focuses on the fact that it is difficult for humans to evaluate one stimulus, but it is relatively easy to compare two stimuli to determine which is better or worse. It is.

For example, if there are three stimuli A1, A2, A3,
y1 = μ + α1, y2 = μ + α2, y3 = μ + α3
And For simplicity, it is assumed that this model is composed only of the total average μ and the main effect αi (i = 1, 2, 3). In addition, the sum of the main effects is set to 0, as in the general constraint necessary for estimating the parameters of the design of experiments (design of experiments).
α1 + α2 + α3 = 0 (1)

The fact that absolute evaluation is impossible means that there is no idea about the value of μ, and that y1, y2, and y3 cannot be measured directly, but as described above, the difference between the two stimuli is taken. Then, μ disappears and can be expressed by the difference of the main effect only.
y1-y2 = (μ + α1) − (μ + α2) = α1-α2 (2)
y1−y3 = (μ + α1) − (μ + α3) = α1−α3 (3)
y2-y3 = (μ + α2) − (μ + α3) = α2-α3 (4)
Where (2) + (3) is
2y1- (y2 + y3) = 2α1- (α2 + α3)
However, 2y1- (y2 + y3) = 3α1 according to the constraint equation (1).
It becomes. That is, the effect of each stimulus can be extracted. And, if the effect of each stimulus at this time is expressed by the following function by the difference in physical characteristics of the image forming apparatus,
α1-α2 = b (x1-x2)
The relationship is obtained. Here, b is a constant, and xi is i = 1, 2, 3,... N. The intercept cancels because it models the difference between the two stimuli.

  Therefore, a model that predicts the difference in evaluation can be obtained by performing multiple regression analysis using the difference in scores as an objective variable, the difference in plural acoustic physical quantities as an explanatory variable group, and a multiple regression analysis. Become. That is, when an acoustic physical quantity of two sounds to be compared is input, a model that can output a prediction of a difference in evaluation such as how discomfort is different between the two sounds is obtained.

  Among the conventional methods, the relative score of each stimulus is calculated by Scheffes's paired comparison method (Ura's modified method), and the score is used as the objective variable, and the sound quality characteristics of the stimulus (psycho-acoustic) Some have obtained a multiple regression model using parameters as explanatory variables.

  However, in the present invention, a conventionally used technique is improved as a device for connecting a plurality of experimental results. That is, in the conventional method, it is necessary to derive a model formula for each experiment, and further, it is necessary to perform pairwise comparisons for all stimulus pairs to derive a score, so the scale of the experiment becomes enormous. For example, when the test sound (stimulus) is 9 sounds, 72 pairs of comparisons are required, and when the sound is 18 sounds, 306 pairs of comparisons are required. In the Scheffe paired comparison method, each subject must perform all pairwise comparisons, but as the number of experiments increases, the subject becomes tired and reacts moderately, and long-term tests are not convenient for the subject. It is difficult to collect subjects.

  In the case of an apparatus with different specifications or a plurality of operation modes such as the image forming apparatus described above, the characteristics of the sound generated by the image forming apparatus when operating in each apparatus or mode are completely different. Although it is possible to derive a plurality of model expressions corresponding to each image forming apparatus and each operation mode, handling is very complicated.

  Therefore, the present inventor makes an assumption that the regression coefficients (straight lines) of the sound quality characteristics are approximately equal in each paired comparison experiment, and the psychoacoustic parameter values of the two stimuli are set as objective variables. We focused on the fact that a unified model formula can be obtained by performing multiple regression analysis with the difference between the two as an explanatory variable. In the present invention, the final evaluation object is not a difference in discomfort but a score of sound discomfort. Therefore, after deriving a model that predicts the difference in discomfort as described above, the model formula derived by setting a reference point is converted to a model formula that predicts the discomfort score of a single sound. .

  The present inventor derives a model formula for predicting a score of sound discomfort according to the above-described idea, and evaluates the sound quality of the sound generated by the image forming apparatus. The process will be described in detail below.

The flow of the sound quality evaluation experiment and the sound quality evaluation formula derivation of the image forming apparatus is as follows.
(1) Collection of operation sound of image forming apparatus (2) Analysis of operation sound (3) Creation of test sound from collected operation sound (4) Measurement of psychoacoustic parameters of test sound (5) By test sound Paired comparison experiment (6) Identification of unpleasant sound source (7) Creation of analysis data of difference model (8) Derivation of formula for predicting difference of score (9) Derivation of model formula (sound quality evaluation formula) for predicting score ( 10) Verification of derived sound quality evaluation formula

Next, details of the above process will be described.
(1) Collection of operation sound of image forming apparatus The operation sound of the image forming apparatus was collected by binaural (binaural) recording using a head acoustic system dummy head HMS (Head Measurement System) III. This is because by performing binaural recording and reproducing with dedicated headphones in this way, it can be reproduced as if a human actually heard the sound generated by the machine.

  In addition, as described above, the image forming apparatus that is a device under test executes image forming operations at three types of image forming speeds according to the operation mode for an image forming apparatus having a plurality of modes. Measurement was performed for each of the three operation modes. Further, since the desktop type (desktop) image forming apparatus, the medium-speed image forming apparatus, and the large-sized (console type) image forming apparatus have only a monochrome single mode, their operations were measured.

The measurement conditions are as follows (see FIG. 9).
・ Recording environment ・ ・ ・ Semi-anechoic room ・ Dummy head 203 ear position (sound collecting position) 204 ・ ・ ・ 1.2m height
Horizontal distance 1 m (1 ± 0.03) from the end face of the device 201 to be measured, the width direction is the center position of the device, the recording direction, ... the front (surface with the operation unit 202 of the image forming apparatus), the rear, and the left and right・ Recording mode ... FF (Free field: for anechoic room)
・ HP filter 22Hz

  The height of the dummy head is set to 1.2 m in consideration of the fact that there are many cases where an instruction is issued from a personal computer or the like while the user is seated as a recent method of using the image forming apparatus. . Of course, the dummy head may be installed at a height of 1.5 m in consideration of a state where a human is standing.

  By the way, the sound emitted by the image forming apparatus is usually different for each direction. This is because the positions of various motors, the sheet conveyance path, and the position of the paper discharge port are not located at the center of the apparatus but are distributed. Therefore, the sound produced by a certain sound source (such as a motor) can be heard well on the right side, but the sound collected for each direction is different, such as not being heard well on the left side. The sample sound used for the experiment described below may be collected in any direction, but when performing a paired comparison experiment, it is necessary to unify the sample sound in any one direction. Therefore, in this experiment, it is considered that the user has the most chances of listening on the front side, while the rear side of the normal image forming apparatus has little opportunity to hear the sound on the rear side that is installed along the wall. Therefore, we decided to use the sampled sound from the front side as the test sound.

(2) Analysis of operation sound Next, the operation sound of the image forming apparatus collected as described above was analyzed. First, when an image forming apparatus having a plurality of modes was analyzed for noise when operating at a color of 28 ppm, that is, at a printing speed of 28 ppm, an analysis result as shown in FIG. 10 was obtained. The upper part of FIG. 10 represents the sound collected on the time axis, and the lower part of FIG. 10 represents the sound collected on the frequency axis. From this result, seven main sound sources were extracted. First, the fixing oil application impact sound of the fixing unit 46 was extracted on the time axis. On the frequency axis, color development drive system sound, paper feed stepping motor sound, charging sound, drum drive stepping motor sound, polygon mirror motor sound, and paper sliding sound were extracted.

  Next, when the noise was analyzed when the color was 14 ppm, that is, when the printing speed was 14 rpm, an analysis result as shown in FIG. 11 was obtained. The upper side of FIG. 11 represents the sound collected on the time axis, and the lower side of FIG. 11 represents the sound collected on the frequency axis. From this result, as the main sound source, the fixing oil application impact sound is extracted on the time axis, and the feeding stepping motor sound, charging sound, drum drive motor sound, polygon mirror motor sound, paper sliding sound are extracted on the frequency axis. Extracted.

  Next, when the noise at the time of monochrome 38 ppm, that is, when operating at a printing speed of 38 ppm, was analyzed, an analysis result as shown in FIG. 12 was obtained. The upper side of FIG. 12 represents the sound collected on the time axis, and the lower side of FIG. 12 represents the sound collected on the frequency axis. From this result, as a main sound source, fixing oil application impact sound was extracted on the time axis, and development drive system sound, charging sound, drum driving stepping motor sound, and paper sliding sound were extracted on the frequency axis.

  Next, when noise was analyzed when the desktop (desktop) image forming apparatus (20 ppm) was operated, an analysis result as shown in FIG. 56 was obtained. The upper side of FIG. 56 represents the sound collected on the time axis, and the lower side of FIG. 56 represents the sound collected on the frequency axis. From these results, metal (clutch / solenoid) impact sound and paper impact sound were extracted on the time axis as main sound sources, and main motor sound and AC charging sound were extracted on the frequency axis.

  Next, when the noise when the medium-speed image forming apparatus (27 ppm) was operated was analyzed, an analysis result as shown in FIG. 57 was obtained. The upper side of FIG. 57 represents the sound collected on the time axis, and the lower side of FIG. 57 represents the sound collected on the frequency axis. From these results, as the main sound source, paper feed sound and metal (clutch / solenoid) impact sound were extracted on the time axis, and main motor sound, paper feed sound, and paper sliding sound were extracted on the frequency axis.

  Next, when the noise when the large-sized (console type) image forming apparatus (65 ppm) was operated was analyzed, an analysis result as shown in FIG. 58 was obtained. The upper side of FIG. 58 represents the sound collected on the time axis, and the lower side of FIG. 58 represents the sound collected on the frequency axis. From these results, paper impact sounds and metal (clutch / solenoid) impact sounds are extracted on the time axis as main sound sources, and paper impact sounds, bank motor sounds, development motor sounds, main motor sounds, paper on the frequency axis. The sliding sound was extracted.

(3) Creation of test sound from the collected operation sound Next, the sound collected at the position on the front side of the device as described above was collected using "ArtemiS" which is sound quality analysis software manufactured by Head Acoustics. The sound was processed.

  As a sound processing method performed in this experiment, a sound during one cycle of the printing operation was cut out from the collected original sound. Then, among the sounds in one cycle period, a filter process was performed on the frequency source or the time axis on the part related to the main sound source extracted as described above, and a process of attenuating or enhancing these parts was performed. That is, three levels of sound (emphasis / original sound / attenuation) were created for each sound source extracted in one mode.

  As described above, the sounds collected on the front, rear, left and right sides of the image forming apparatus are different from each other, but on the front side created in this experiment rather than the range of psychoacoustic parameter values obtained from such four-direction sounds. It has been confirmed that the range of psychoacoustic parameter values obtained from three test sounds obtained by emphasizing and attenuating the collected sounds is wider. In other words, a subjective evaluation experiment using three sounds obtained by emphasizing and attenuating sounds collected on the front side as in this experiment covers the characteristics of sounds obtained from sounds collected in four directions. Therefore, the discomfort in the four directions can be calculated from the sound quality evaluation formula.

  Based on the sound collected on the front side as described above, if three levels of sound (emphasis, original sound, attenuation) are created from the sound emitted by the main sound source extracted for each image forming apparatus, the sound generated at the time of each image formation Nine sounds were created based on the L9 orthogonal table with different levels of sound sources extracted for. In the subjective evaluation experiment, it is necessary to perform a brute force comparison experiment. Therefore, in the case of nine sounds, the comparison order was taken into consideration, and one subject made 72 comparisons at a time.

  First, an image forming apparatus having a plurality of modes will be described. Tables 2 to 5 are descriptions regarding the respective modes of the image forming apparatus having a plurality of modes. Here, Table 2 shows three-level sounds created for the main sound sources (seven) extracted from sounds collected when the image forming apparatus having a plurality of modes operates at a color of 28 ppm, that is, at a printing speed of 28 ppm. The result of having created nine test sounds by allocating based on the L9 orthogonal table is shown. By assigning to the orthogonal table in this manner, there is no correlation between the factors (sound source level changes), and therefore analysis can be performed ignoring changes in other factors.

  In the above table (the same applies to the following tables), “−1” is a sound created by attenuation until the sound is almost inaudible, “0” is a sound at the level of the original sound, and “1” is the original sound. The sound is emphasized until the difference in level is clearly seen. For example, the test sound “color 28 ppm [9]” in Table 2 is “0” for all sound sources, indicating that all remain as the original sound.

  In Table 2, the subjective evaluation value (score) of each test sound obtained by a comparative method experiment described later is also shown. Note that the total of subjective evaluation values (total of nine sounds) in the table is set to be zero.

  Next, Table 3 shows three-level sounds created for the main sound sources (six) extracted from sounds collected when operating at 14 ppm color, that is, at a printing speed of 14 ppm, based on the L9 orthogonal table. Results are shown. However, since the charging sound, the drum driving stepping motor sound, and the polygon mirror motor sound are the sounds of the same tonality component, each test sound was set to the same level. The paper feed stepping motor sound is also a tonality component, but since this is an intermittently generated sound, it was decided to swing the level separately from the motor sound.

  Table 4 shows the result of allocating three-level sounds created for the main sound sources (five) extracted from sounds collected when operating at 38 ppm monochrome, that is, at a printing speed of 38 ppm, based on the L9 orthogonal table. Indicates. However, since the charging sound and the drum driving stepping motor sound have the same tonality component, each test sound has the same level.

  Also, in this experiment, three levels of sound were obtained from the psychoacoustic parameters loudness value, sharpness value, tonality value and impulsiveness value obtained from the sound collected in the front when the above three modes were mixed. (Emphasis, original sound, attenuation) were created, and these sounds were assigned based on the L9 orthogonal table to create test sounds. The results are shown in Table 5.

  In addition, regarding the assignment of the loudness value, the emphasis was given for 38 ppm of monochrome, the intermediate one for 28 ppm, and the attenuated one for 14 ppm. That is, each level value of loudness was assigned according to the printing speed. The numerical values in parentheses in the table indicate each parameter value. In this experiment, since the effect of the printing speed (ppm), that is, the effect of the printing speed is also confirmed, the effect cannot be analyzed if the printing speed and the loudness value change in a completely proportional manner. Therefore, as shown in Table 5, even if the loudness values are the same level, a difference of about 1 (one) is given to make a difference in the level of hearing.

  Similarly, similar operations were performed on image forming apparatuses at other speeds. Table 6 shows the result of allocating three levels of sounds created for the main sound sources (four) extracted from the sound collected when operating at monochrome 20 ppm based on the L9 orthogonal table.

  Table 7 shows the result of allocating three levels of sounds created for the main sound sources (four) extracted from the sound collected when operating at monochrome 27 ppm based on the L9 orthogonal table.

  Table 8 shows the result of allocating the three levels of sounds created for the main sound sources (six) extracted from the sound collected when operating at 65 ppm monochrome based on the L9 orthogonal table.

  Also, in this experiment, three values were obtained from the loudness value, sharpness value, tonality value, and impulsiveness value, which are psychoacoustic parameters obtained from the sound collected at the front when the three speeds of the monochrome machine were mixed. Level sounds (emphasis, original sound, attenuation) were created, and these sounds were assigned based on the L9 orthogonal table to create test sounds. The results are shown in Table 9.

  Furthermore, the six sounds related to the image forming apparatus having a plurality of modes (14 ppm color, 28 ppm color, 38 ppm monochrome) and the six sounds of the image forming apparatus having the monochrome single mode were compared. Table 12 shows the 12 sounds.

  The above is the details of the process of creating a test sound from the collected operating sound and creating an experiment.

(4) Measurement of psychoacoustic parameter value of test sound Next, the psychoacoustic parameter of the test sound created as described above was obtained using the sound quality analysis software “ArtemiS” manufactured by Head Acoustics. In this sound quality analysis software, various settings can be selected when obtaining psychoacoustic parameter values. In this experiment, default settings were adopted.

  For example, for loudness, [FET / ISO0532], [Filter / ISO0532], and [FET / HEAD] can be selected as [Calculation method], but the default [FET / ISO0532] is adopted, and [Spectrum Size] is the default. No. “4096”. As for sharpness, the default [FET / ISO0532] was adopted for [Calculation method], and the default [Aures] among [Aures] and [von Bismrck] was adopted for [Sharpness method]. [Spectrum Size] was performed with the default “4096”. Other psychoacoustic parameter values correlate with loudness and automatically change depending on the loudness setting.

  Using the sound quality analysis software set as described above, the psychoacoustic parameter values of the test sound created in the process of (3) above were obtained. The results are shown in Tables 11-1 and 11-2.

(5) Paired comparative method experiment using test sound Next, subjects who have the test sound created as described above are evaluated are collected and provided to each subject for each model or mode (Table 2 to Table 10). A pair of test sounds [1] to [9] (12 samples of the test sound in Table 10) were compared to determine which is uncomfortable.

  In the comparison experiment, all combinations of two test sounds are extracted from nine test sounds, and N subjects compare all of the combinations. That is, since there are nine test sounds in one mode, there are 72 combinations, and the subject is made to compare them. Therefore, the evaluation for the combination of the sample sound [1] and the sample sound [2] is different from the evaluation for the combination of the sample sound [2] and the sample sound [1]. Combinations with different values are also subject to experimentation.

  In this comparison, for example, the test sound [1] and the test sound [2] are compared, and if the subject evaluates the test sound [1] as uncomfortable, “1 point” When [2] is uncomfortable, the result is “−1 points”, and the results are collected and subjected to statistical processing. As a result, relative subjective evaluations in the range of −1 to 1 with respect to nine test sounds Got the value. Such subjective evaluation values are also shown in Tables 2 to 5. Since the evaluation as described above is performed, it means that the larger the subjective evaluation value, the more unpleasant.

  For the combinations shown in Table 10, the scale of the experiment becomes large when a pairwise comparison of 12 sounds is performed. In this experiment, the sounds of the image forming apparatuses having a plurality of modes and the sounds of the image forming apparatuses of the monochrome single mode are compared. Was not carried out since it was conducted in another experiment (group I and group III, group II and group IV in the table below were not compared).

  That is, [1] Group I and Group II, [2] Group I and Group IV, [3] Group II and Group III, and [4] Group III and Group IV were only compared. Considering the order of comparison, one subject made 72 comparisons at a time. Since it is not a brute force pair comparison, a relative score of 12 sounds cannot be calculated, but difference data of discomfort of 2 sounds can be obtained.

(6) Identification of unpleasant sound source Next, the unpleasant sound source is identified by six operating sounds of “color 28 ppm”, “color 14 ppm”, “monochrome 38 ppm”, “monochrome 20 ppm”, “monochrome 27 ppm”, and “monochrome 65 ppm”. It carried out for every experimental result implemented. Here, FIGS. 13 to 27 are graphs showing the relationship between the levels (emphasis, original sound, attenuation) of each sound source shown in Tables 2 to 4 and the subjective evaluation values.

  59 to 62 are for Table 6, FIGS. 63 to 66 are for Table 7, and FIGS. 67 to 72 are for each sound source level (emphasis, original sound, attenuation) and subjective evaluation values. The relationship is shown in a graph.

  In this graph, the vertical axis represents the subjective evaluation value α, which means that the higher the value is, the more uncomfortable it is. The horizontal axis of the graph is the level of the sound source, that is, the sound pressure level level, “−1” attenuates the sound source, “0” remains the original sound, and “+1” emphasizes the sound source.

Further, “R ² ” in each figure is a contribution rate, and “R” is a correlation function. Here, the contribution rate indicates what percentage the sound source contributes to discomfort. In the case of the result shown in FIG. 13, it is shown that the fixing oil application impact sound contributes 51% to discomfort. That is, if the correlation between the sound source level change and the subjective evaluation value (discomfort) change is high, the contribution rate increases. Note that the total contribution rate of each sound source in one mode is 100%, but there are some that are not exactly 100% due to rounding.

First, an unpleasant sound source of an image forming apparatus having a plurality of operation modes is examined.
Referring to the contribution ratio of each sound source of “Color 28 ppm” shown in FIGS. 13 to 19, the color development driving sound system, the paper feeding stepping motor sound, the charging sound, and the polygon mirror motor sound hardly contribute to the unpleasantness. I understand that. However, according to later analysis, the three sound sources of the feeding stepping motor sound, charging sound, and polygon mirror motor sound are strongly related to the tonality (pure tone) component, which is actually unpleasant, but if the frequency of the pure tone is close, no measures are taken at the same time And found that discomfort is not improved. Therefore, in other modes, these sound sources are set to the same level for each sample sound (see the process (3) and Tables 3 and 4). For this reason, only the color development driving sound among the sound sources hardly contributes to discomfort, so it is considered that there is no need for noise countermeasures. However, there are cases where improvement is necessary in the evaluation based on the sound power level.

  On the other hand, the “color 28 ppm” contributes most unpleasantly to the fixing oil application impact sound, and the next contributing element is the paper sliding sound.

  According to the unpleasant sound source analysis results of “Color 14 ppm” shown in FIGS. 20 to 23, fixing oil application impact sound 43%, paper sliding sound 35%, paper feed stepping motor sound 17%, charging sound, polygon mirror motor sound The total of the three sound sources of the drum drive motor sound was 3%.

  According to the unpleasant sound source analysis result of “monochrome 38 ppm” shown in FIGS. 24 to 27, the fixing oil application impact sound 43%, the paper sliding sound 35%, the sum of the charging sound and the drum drive motor sound is 10%, and the development drive The sound system was 3%.

  From the above analysis results, in the image forming apparatus having a plurality of modes, the sound source other than the sound of the development drive system contributes to unpleasantness, and the uncomfortableness is reduced by taking noise countermeasures for these sound sources. You can see that

Next, an unpleasant sound source of the desktop (desktop) image forming apparatus is examined.
Referring to the contribution ratio of each sound source of “monochrome 20 ppm” shown in FIGS. 59 to 62, the main motor sound was 21%, the metal impact sound was 29%, the AC charging sound was 45%, and the paper impact sound was 2%.

  In the desktop type (desktop) image forming apparatus, it can be seen that sound sources other than the impact sound of paper contribute to discomfort, and that discomfort is reduced by taking noise countermeasures for these sound sources.

Next, an unpleasant sound source of the medium-speed image forming apparatus is examined.
Referring to the contribution ratios of the sound sources of “monochrome 27 ppm” shown in FIGS. 63 to 66, the paper feed sound was 9%, the paper sliding sound was 61%, the metal impact sound was 13%, and the motor drive system sound was 1%. .

  In the medium-speed image forming apparatus, the paper sliding sound and the metal impact sound contribute to the uncomfortableness, and it can be understood that the discomfort can be reduced by taking noise countermeasures for these sound sources.

Next, an unpleasant sound source of the large (console type) image forming apparatus is examined.
Referring to the contribution ratio of each sound source of “monochrome 65 ppm” shown in FIGS. 67 to 72, metal impact sound 29%, paper sliding sound 42%, paper impact sound 0%, bank motor sound 3%, development motor sound 10%, main motor sound 1%.

  In a large-sized (console type) image forming apparatus, metal impact sound and paper sliding sound contribute to discomfort, and it can be seen that discomfort can be reduced by taking noise countermeasures for these sound sources.

(7) Creation of difference model analysis data Next, using the experimental results obtained by the paired comparison experiment in the process of (5) above, the difference between the subjective evaluation values (scores) of two sounds is calculated, and the psychoacoustic parameters Data of difference of values was created, and multiple regression analysis was performed for both. The method of creating such difference data is as follows.

  When there are 35 subjects in the paired comparison experiment, the test sound [1] is compared with the test sound [2]. If the test sound [1] is unpleasant, “1 point” A case where the sound [2] is uncomfortable is calculated as “−1 point”. In this case, if there are two people who are uncomfortable with the test sound [1] and 33 people who are uncomfortable with the test sound [2], the total score is 2-33 = −31. Become. The value obtained by dividing this value by the number of subjects (35) is the difference “−0.886” in the subjective evaluation value (score).

  Table 12 (Summary of difference data) shows a part of the difference between the scores calculated as described above and the psychoacoustic parameter values (analysis data of the difference model). Table 12 shows a part of the results for the test sound of “color 28 ppm [1] to [9]”.

  The calculation of the difference between the subjective evaluation values and the difference between the psychoacoustic parameters, that is, the difference between the psychoacoustic parameter values (see Table 6) of the test sound [1] and the test sound [2] in the above example, Calculation of all combinations of test sounds (72 patterns per experiment, total of 648 patterns of 9 experiments in Tables 2 to 10 and 56 patterns of experiments using other machines, totaling 704 patterns) To do. At that time, if it was determined that the sound of one person was unpleasant in the paired comparison method experiment, the individual could not be measured because the measurement of the magnitude of the discomfort difference was overscaled and could not be measured. Excluded. As a result, 638 types of difference data were obtained.

(8) Deriving Formula for Predicting Score Difference As described in the above-mentioned idea of the present inventor, in order to accurately measure a subjective evaluation value (objective variable), a plurality of psychoacoustic parameters (explanatory variable group) It is effective to perform multiple regression analysis using That is, in single regression analysis, the objective variable is predicted with a single explanatory variable, so the accuracy may not be good, but in multiple regression analysis, the objective variable is predicted with multiple explanatory variable groups, so the accuracy is good. ,It is valid.

  The multiple regression analysis can be performed using various commercially available spreadsheet software and statistical analysis software. For example, regression analysis of spreadsheet software “Excel (registered trademark of Microsoft)”, statistical analysis software “JMP (registered trademark of SAS Institute Inc)” or “SPSS (registered trademark of SPSS Inc)” is used. can do. By inputting the data (subjective evaluation value difference and psychoacoustic parameter difference) in Table 7 above into “Excel” and “JMP” and performing analysis while selecting explanatory variables, the regression coefficient and the selected explanation Statistical results such as the P value of the coefficient and the contribution ratio of the equation are output. Here, the P value is the probability of a significant difference test, and is determined to be significant at 5% or less and not significant (not related) at 5% or more.

  Using the software as described above, a multiple regression analysis was performed using the difference in scores calculated in the process (7) as an objective variable and the difference in psychoacoustic parameter values and the difference in ppm values as explanatory variable groups. In this multiple regression analysis, the score itself is not used as an objective variable, but the difference in scores is used as an objective variable, so the intercept (constant term) is set to zero. In the variable selection, physical quantities such as sound pressure level, loudness, sharpness, tonality, and impulsiveness were selected, and the multiple regression analysis gave the analysis of variance table shown in Table 13 and the regression analysis result shown in Table 14. . The ppm value was not selected because it has a strong correlation with the loudness value. It was also confirmed that the interaction between these physical quantities was not significant.

  Here, since the contribution ratio = the sum of squares by regression / the total sum of squares, the contribution ratio is 6059.1507 / 7983.5872 = 0.76 from the results shown in Table 13 (ANOVA table). In other words, it was found that the five selected parameters (sound pressure level, loudness, sharpness, tonality, impulsiveness) contribute 76% to discomfort.

  As shown in Table 14 (Regression analysis result), the regression analysis result includes a partial regression coefficient (regression coefficient at the time of multiple regression analysis) of the selected five parameters, and a partial bias having a reliability of 95% or more. The upper limit value and lower limit value of the regression coefficient (that is, the range of the partial regression coefficient having a reliability of 95% or more) are also included. These upper limit value and lower limit value represent values (2σ) approximately twice the standard deviation corresponding to the estimated values of the partial regression coefficients, in the range of ±. Since the values of the partial regression coefficients are all positive, it can be seen that the difference in discomfort increases as the difference in parameter values increases in the positive direction.

When the difference model is expressed as an equation, the following equation (a) is obtained.
αi−αj = + 0.0522715 × (x sound pressure level i−x sound pressure level j)
+ 0.1580369 × (x loudness i−x loudness j)
+ 0.4136496 × (x sharpness i−x sharpness j)
+ 2.96777803 × (x tonality i−x tonality j)
+ 1.2913747 × (x impulsiveness i−x impulsiveness j)
... (a)
.alpha.n (n = 1, 2,..., i,..., j,...): subjective table value for sound discomfort (score)

  By substituting two psychoacoustic parameter values as described above, a line format that can calculate the difference in discomfort (score) was derived.

  Here, FIG. 28 shows the actually measured value of the difference of the scores, the predicted value of the difference of the scores derived using the above equation (a), and a scatter diagram. From this figure, it can be seen that the actual measured value of the difference in the scores can be in the range of −1 to 1 as described above, but the predicted value is in the range of about −1.6 to 1.6.

(9) Derivation of a sound quality evaluation formula for predicting a score In the above-described equation (a), a predicted value can be derived for a difference in scores, but in the sound quality evaluation, the score itself is finally required. Therefore, a sound quality evaluation formula that can predict the score from the above-described difference model of the score was derived as follows.

  First, the average value of each test sound used in the experiment as each psychoacoustic parameter is substituted into equation (a), and α0 = 0 at that time, that is, the discomfort of the sound when each parameter value is average The intercept is obtained by defining the length as “0”.

That is, the sample sound used in the experiment was set as 0 for the effect α0 of the coordinates of the center of gravity, x sound pressure level 0, x loudness 0, x sharpness 0, x tonality 0, x impulsiveness 0 at that time (Table 11) is substituted.
Αi−αj = + 0.0522715 × (x sound pressure level i−x sound pressure level j) in the above formula (a)
+ 0.1580369 × (x loudness i−x loudness j)
+ 0.4136496 × (x sharpness i−x sharpness j)
+ 2.96777803 × (x tonality i−x tonality j)
+ 1.2913747 × (x impulsiveness i−x impulsiveness j)
... (a)
Substituting the average value of each psychoacoustic parameter for, the intercept can be calculated.

x sound pressure level 0 = 53.38
x loudness 0 = 7.84
x Sharpness 0 = 2.33
x Tonality 0 = 0.10
x Impulsiveness 0 = 0.55
If you enter an average value,
αi−α0 = + 0.0522715 × (x sound pressure level i−x sound pressure level 0)
+ 0.1580369 × (x loudness i−x loudness 0)
+ 0.413664 × (x sharpness i−x sharpness 0)
+ 2.96777803 × (x tonality i−x tonality 0)
+ 1.2913747 × (x impulsiveness i−x impulsiveness 0)
αi-0 = + 0.0522715 × (x sound pressure level i−53.38)
+ 0.1580369 × (x loudness i−7.84)
+ 0.4136496 × (x sharpness i−2.33)
+ 2.9967803 × (x tonality i−0.10)
+ 1.2913747 × (x impulsiveness i−0.55)
αi = + 0.0522715 × (sound pressure level value) + 0.1580369 × (loudness value)
+ 0.413664 × (Sharpness value) + 2.6283418 × (Tonality value) + 1.56852929 × (Impulsedness value) −5.999889619
If this αi is defined as the sound discomfort index S, it is as follows.

From above,
S = + 0.0522715 × sound pressure level i
+ 0.1580369x loudness i
+ 0.4136496x Sharpness i
+ 2.6283418x Tonality i
+ 1.5681529x Impulsiveness i
-5.999889619

  From this equation, if the sound element corresponding to each psychoacoustic parameter is reduced, that is, [1] the sound pressure level is reduced, [2] the volume of hearing is reduced (loudness), and [3] the high frequency component is reduced. It has been found that discomfort can be reduced by reducing (sharpness), [4] reducing pure tone components (tonality), and [5] reducing impact sound (impulsivity).

  As described in (8) above, since the partial regression coefficient range having a reliability of 95% or more obtained as the regression analysis result shown in Table 9 is used, the intercept range is also the upper limit of each partial regression coefficient. It is a value obtained by substituting the value and the lower limit value (the upper limit value substitution intercept is -7.2246314, the lower limit substitution intercept is -4.7741981).

When the above equation is modified assuming that the coefficient and the intercept can be taken within this range, the following equation (a) is obtained.
S = A × (sound pressure level value) + B × (loudness value) + C × (sharpness value) + D
X (Tonality value) + E x (Impulsedness value) + F
Range of the coefficient of restitution for each parameter 0.037865 ≦ A ≦ 0.066678
0.126588 ≦ B ≦ 0.189486
0.367910 ≦ C ≦ 0.459389
2.532697 ≦ D ≦ 3.402664
1.132176 ≦ E ≦ 1.450574
−7.246314 ≦ F ≦ −4.7741981
(A)

(10) Verification of derived sound quality evaluation formula Next, it was decided to verify the prediction accuracy of the score prediction formula (sound quality evaluation formula) derived as described above.

  FIG. 29 shows each of eight experiments (“Color 28 ppm”, “Color 14 ppm”, “Monochrome 38 ppm”, “Mode Mix”, “Monochrome 20 ppm”, “Monochrome 27 ppm”, “Monochrome 65 ppm”, “Monochrome Mix”). FIG. 5 is a graph in which values predicted using the above formula (a) (horizontal axis) and measured values (vertical axis) are compared and plotted. Table 10 shows a comparison between six sounds related to an image forming apparatus having a plurality of modes (color 14 ppm, color 28 ppm, monochrome 38 ppm) and six sounds related to an image forming apparatus having a monochrome single mode. Since it is not a comparison of hit combinations, a relative score of 12 sounds cannot be calculated. For this reason, it was not possible to plot on the graph.

  As shown in the figure, the overall slope of this graph is 0.9942, which is almost 1, and the overall contribution rate is 92%. Therefore, in any of the eight experiments, it is considered that the accuracy of the predicted value of the score derived by the above equation (a) is high. In the predicted value of the difference between the scores shown in FIG. 2, there was a deviation from the measured value in the vicinity of the score differences “1” and “−1”. From the results shown in FIG. It can be said that the accuracy of the value has been improved. This is because the formula for deriving the difference in scores had 638 predicted values, that is, plot values, whereas in formula (a), the average number of plots of 72 predicted values was averaged, and thus the variation was considered to be reduced. It is done.

  In practice, an intercept (constant term) is attached for each of the eight experiments. This is the relative origin (center of gravity) for each experiment when obtaining a score (subjective evaluation value = actual measurement value). ) Is adjusted. The reason why the constant term is necessary is that calculation is performed with a constraint that the sum of the scores in each experiment is zero. In other words, in the process of (9) above, the intercept was obtained by substituting the average value of the sound pressure level, loudness, sharpness, tonality, and impulsiveness of the test sound used in the experiment. Different for each of the eight experiments (see Table 6). For example, the average loudness of “color 28 ppm” is 6.59 (sone), whereas the average loudness of “color 14 ppm” is 5.70 (sone).

  The predicted values plotted in the graph shown in FIG. 29 are obtained by substituting the average value for each experiment as described above.

  On the other hand, in the expression (a) derived as described above, which is derived this time, there is no restriction that the sum of the scores of the test sound must be 0, and the degree of coincidence of the inclinations of the expressions should be noted. Therefore, in order to obtain the graph shown in FIG. 29, the adjustment of substituting the average value for each experiment as described above is unnecessary. The reason why adjustment was performed when obtaining the graph shown in FIG. 29 was that it was necessary to verify the accuracy of the predicted value by comparing the measured value and the predicted value of each experiment. Table 15 shows the adjustment values for reference. When the value of “difference from the overall average” is added to the value of the intercept obtained by substituting the average value for each mode, an equation similar to the above equation (a) is obtained.

  Now, it is considered that the accuracy of the predicted value (evaluation) obtained by the equation (a) derived as described above is high, but when the discomfort index S, which is the evaluation obtained in this way, becomes a value, the person is uncomfortable. It is important to feel that. Therefore, the following experiment was conducted to confirm this. For the test sound of color -14ppm, color 28ppm, monochrome 38ppm, monochrome 65ppm, the test subject asked all the test sounds [1] to [9] for each speed experiment, and then listened one sound at a time. An experiment was conducted in which each test sound was evaluated for three levels of discomfort.

Since the test sound of 65 ppm monochrome was larger between the test sound [1] and the test sound [5] than the interval between the other sounds, the test sound [1] and [5] The unevaluated test sounds 10 and 11 prepared in advance were prepared. The physical quantities of the test sounds 10 and 11 are shown in Table 20.
As a result, the results shown in Tables 16 to 19 were obtained.

  In the table, “A” is an acceptable sound, “C” is an unacceptable sound, and “B” is an intermediate sound. Of the sound quality evaluation values of the sound evaluated as “A” (values calculated by the expression (a)), assuming that the largest value is an allowable value, ppm of each experiment and image formation speed (mm / s) The allowable values for each are as shown in Table 21.

FIG. 30 is a graph in which the relationship between the ppm value and the allowable value is approximated based on the results shown in Table 21. The approximate expression is
S ≦ 0.4818Ln (ppm) −1.586 • (b)
14 ≦ ppm ≦ 65
It is.

FIG. 31 is a graph in which the relationship between the image forming speed (mm / s) and the allowable value is approximated based on the results shown in Table 21. The approximate expression is
S ≦ 0.4248Ln (v) −2.4301 (d)
62.5 ≦ v ≦ 362

  As shown in Table 21, if the discomfort index S calculated from the sound generated when operating at each speed (ppm or image forming speed mm / s) is less than or equal to the allowable value, the discomfort is hardly felt. .

  As described above, by using the formula in FIG. 29 or formula (a), it is uncomfortable to obtain only psychoacoustic parameter values that can be obtained from physical quantities of sound without actually performing subjective evaluation experiments. The discomfort index S, which is an evaluation of Even if the apparatus has a plurality of operation modes having different image forming speeds (mm / s and ppm) and the image forming apparatus has different image forming speeds by the above formulas (b) and (d), It is possible to determine what value is the discomfort index S obtained for each of them so as not to cause discomfort.

  The above is the method for evaluating the quality of sound emitted by the image forming apparatus and the method for deriving the sound quality evaluation formula used for the sound quality evaluation.

C. As described above, the present invention is a remodeling method for evaluating noise generated by the image forming apparatus as described above, and taking measures for reducing discomfort caused to the person by the noise based on the evaluation. A specific example of countermeasures for reducing the image forming apparatus having the above-described configuration and reducing the unpleasant feeling caused by the sound generated by the image forming apparatus will be described.

  First, in order to evaluate the sound emitted by the image forming apparatus, the sound emitted by the image forming apparatus is collected by the same method as (1) described above. Here, the sampling position is the position of a neighbor (see FIG. 9) defined in ISO 7779, at a distance of 1.00 ± 0.03 m from the projection of the horizontal plane of the reference box, and the height is 1.2 on the floor. The position is ± 0.03 m or 1.5 ± 0.03 m.

  Also, as shown in FIG. 9, sounds are collected on all four sides, such as the front, left and right sides, and the rear side where the operation unit is provided, and psychoacoustic parameters are obtained from the respective sound collection results to obtain the discomfort index S as the sound quality. It may be determined by an evaluation formula to determine whether or not the discomfort index S for each surface is within an allowable value, or the discomfort index S from the sound collection results collected only on the front surface or only one surface side. It is also possible to make a determination by obtaining.

  Further, an average value of psychoacoustic parameter values obtained from sounds collected on the four sides may be derived, and it may be determined whether or not the discomfort index S obtained from the average value is within an allowable value.

  In order to prevent people on any of the four sides from feeling uncomfortable, it is preferable to collect sound at all positions on the four sides. Satisfactory evaluation can also be made by collecting sound on the front side, which has high characteristics.

  When the discomfort index S obtained as described above exceeds the above-described allowable value, there is a high possibility that the person feels uncomfortable, so that each part of the apparatus is set so that the discomfort index S is below the allowable value. Various modifications are made to. On the other hand, when the discomfort index S is less than or equal to the allowable value, it is possible to determine that there is little possibility that a person feels uncomfortable and that it is not particularly necessary to take noise countermeasures.

  As described above, the discomfort index S lowers the sound pressure level, reduces the volume of hearing (loudness), reduces high frequency components (sharpness), reduces pure tone components (tonality), and reduces impact sound ( By taking measures such as impulsiveness, it can be reduced, and by reducing this, discomfort given to people can be reduced. Therefore, a specific countermeasure example for reducing the psychoacoustic parameters will be described below.

(1) Tonality (Pure Tone Component) Reduction Measures Regarding Image Forming Apparatus Having Multiple Modes (1-1) Drum Drive Stepping Motor Sound Reduction First, an example of tonality reduction measures will be described. As a measure for reducing tonality, there is a method of reducing drum drive stepping motor sound. As shown in FIGS. 10, 11 and 12, the drum drive motor generates a sound in any of the operation modes. And this sound contains many frequency components of the input pulse to the stepping motor.

  32 and 33 are views showing a drum drive mechanism including a color drum drive motor 41 and a black drum drive motor 42 before modification. As shown in these drawings, the color drum drive motor 41, the black drum drive motor 42, and the gears 43 and 44 are held by a motor bracket 59.

  The motor bracket 59 is a member obtained by giving strength to a sheet metal by drawing or the like. A housing attachment portion (screw hole or the like) of the image forming apparatus is formed by bending, and the motor bracket 59 is fixed to the housing at this attachment portion.

  Four gears 44 arranged side by side are rotatably held by the motor bracket 59. Of these gears 44, the rightmost gear 44 in FIG. 32 and the gear 61 attached to the motor shaft of the black drum drive motor 42 are engaged with each other. As a result, the gear 44 is rotated by the black drum driving motor 42, and the photosensitive drum 28 for monochrome image formation (see FIG. 3) is rotated accordingly.

  Of the three gears 44 other than the gear 44 described above, the two left-side gears 44 in FIG. 32 are rotated by the motor shaft 62 of the color drum drive motor 41.

  Further, the second gear 44 and the third gear 44 from the left are both meshed with the relay gear 43, whereby the third gear 44 is rotated with the rotation of the second gear 44. That is, with the rotation of the color drum drive motor 41, the three gears 44 are rotated, whereby the C, M, and Y photoconductive drums 28 (see FIG. 3) are rotated simultaneously. Yes.

  The gear for driving the photosensitive drum as described above adopts a special anti-vibration structure etc. for the motor installation so that the distance between the shafts of the gear can be accurately adjusted to the design value with module 0.5. Not done. That is, the black drum drive motor 42 and the color drum drive motor 41 are directly attached to the motor bracket 59 and fixed.

  By directly attaching the motor to the motor bracket 59 in this way, the vibration of the motor during operation propagates to the motor bracket 59 solidly and is amplified and radiated. The sound generated due to this is a sound containing a lot of driving frequency components of the stepping motor which is a drum driving motor.

  In order to reduce the generation of a sound with a significant driving frequency component of such a stepping motor, the color bracket driving motor 41 and the black drum driving motor 42 are connected to a motor bracket 65 via an anti-vibration rubber mount 60 as shown in FIG. To be attached to. That is, the anti-vibration rubber mount 60 serves as a reduction means for reducing the sound generated as described above.

  As the anti-vibration rubber mount 60, for example, a stepping motor mount made by NOK Co., Ltd. can be used, and the stepping motor mount is used in a test to test the effect of noise countermeasures described later.

  A drum drive mechanism in which an anti-vibration rubber mount 60 is interposed between the motor bracket 65 and the drum drive motor will be described with reference to FIGS. 35 and 36. FIG.

  If the anti-vibration rubber mount 60 is interposed between the drum drive motor and the motor bracket 65, the accuracy of the inter-shaft distance of each gear deteriorates. For this reason, this drum drive mechanism is configured to transmit the driving force from the motor shaft to the gear 44 and the like via the timing belt mechanism, instead of directly engaging the motor shaft with the gear.

  More specifically, timing pulleys 66 and 67 are attached to the motor shafts of the color drum driving motor 41 and the black drum driving motor 42, respectively, and a two-stage gear / motor is driven by the timing belt 70 wound around the timing pulleys 66 and 67. The driving force of the motor is transmitted to the pulleys 63 and 64. That is, the two-stage gear / pulleys 63 and 64 are rotated with the rotation of the motor shaft.

  The two-stage gear / pulley gear is engaged with the drum driving gear 44 described above. As a result, the gear 44 can be rotated in accordance with the rotation of the drum drive motor, and the photosensitive drum 28 (see FIG. 3) can be rotated, as in the configuration before the remodeling.

  The motor bracket 65 is bent so that the portion that holds the motor (the lower portion in FIG. 36) protrudes to the opposite side of the motor from the upper portion. The anti-vibration rubber mount 60 is arranged in contact with the motor bracket 65 in the space formed in the protruding portion, and the motor (41, 42) on the opposite side of the anti-vibration rubber mount 60 from the motor bracket 65 has its motor shaft mounted on the motor bracket 65. Is arranged so as to protrude from the surface on the opposite side (left side in FIG. 36). In this manner, the structure is such that the motor bracket 65 and the motor are not directly held, but are held with the anti-vibration rubber mount 60 interposed therebetween.

  In this configuration, the two-stage gears / pulleys 63 and 64 are arranged on the left side of the motor bracket 65 in FIG. 36 (the side on which the gear 44 is arranged), so that the motor shaft protrudes to the left side in FIG. It is necessary to let However, by forming a protruding portion on the motor bracket 65 as described above, the motor arrangement position itself can be set to the left side of FIG. 36, thereby eliminating the need to lengthen the motor shaft. Therefore, it is possible to suppress the eccentricity of the motor shaft that may be caused by lengthening the motor shaft and the generation of noise caused by the eccentricity.

  In this configuration, it is preferable to increase the strength of the stud 69 for attaching the two-stage gear / pulleys 63 and 64. If the strength of the stud 69 is insufficient, the gear 44 and the two-stage gear / pulley are engaged with each other while being eccentric, and the drum shaft 68 is also eccentric via the bearing 70. This is because the eccentricity of the drum shaft 68 may affect the image formed on the paper, and it is necessary to increase the strength of the stud 69 in order to prevent such a problem.

  In addition to the above-described anti-vibration rubber mount, an elastic body that can absorb the vibration of the motor to some extent may be used. The above is a measure for reducing the noise of the drum driving stepping motor.

(1-2) Reduction of Stepping Motor Sound for Paper Feeding Next, measures for reducing the noise of the stepping motor for paper feeding will be described. As described above, the sheet feeding motor of the image forming apparatus is the stepping motor 56 (see FIG. 8), and the conveyance of the sheet from the tray is performed by controlling the driving of the stepping motor. As a measure for reducing the motor noise, there is a method of setting the drive control contents of the stepping motor 56 as follows, and the control contents will be described below.

  FIG. 37 is a diagram for explaining the movement of the rotor of the stepping motor driven at the step angle θ0. The step angle of the stepping motor is determined by the mechanical structure. Normally, the rotor moves at a time by such a step angle θ, so if the step angle θ is large, the movement is not smooth and vibrations occur. This causes noise.

  Therefore, in this configuration, so-called micro-step driving is performed in which the stepping motor is driven at a step angle smaller than the step angle θ determined by the mechanical structure by control by an electronic circuit as shown in the figure. That is, by performing current supply control such that the current value supplied to one phase of the excitation phase is gradually increased while the current value supplied to the other one phase is gradually decreased ([1] to FIG. 37). [5]), it is possible to drive at a step angle smaller than the step angle θ, to smooth the movement, and to reduce noise.

  FIG. 38 is a diagram showing a 1-2 phase excitation sequence which is one of microstep driving of the stepping motor. 1-2 phase excitation is an excitation method that alternately repeats one phase excitation for exciting a coil one phase and two phase excitation for exciting a coil two phases. When a stepping motor is driven using this excitation method, The motor step angle is halved, and the movement of the rotor is smoother than normal driving, and vibration can be reduced.

(1-3) Reduction of Polygon Mirror Motor Sound Next, a countermeasure for reducing the sound generated by the polygon mirror motor will be described with reference to FIG. As shown in the figure, in this measure, a Helmholtz resonator 71 is attached in the vicinity of the polygon mirror motor 2. More specifically, a Helmholtz resonator 71 is attached to the upper part of the housing 11 that holds the polygon mirror motor 2.

  The Helmholtz resonator 71 has a cavity forming member 72a for forming a cavity 72 having a volume V1. The cavity forming member 72 a is formed integrally with the housing 11, and an opening hole 73 (cross-sectional area Sb) leading to the cavity 72 is formed at a portion facing the polygon mirror motor 2. Here, if the thickness of the portion where the opening hole 73 is formed is Tb, the opening hole 73 corresponds to a short tube having a length Tb and an opening area Sb in a general Helmholtz resonator. This structure functions as a Helmholtz resonator 71.

  With this configuration, when the polygon mirror motor 2 is driven and a sound pressure acts on the entrance of the opening hole 73 due to the vibration, the air (medium) in the opening hole 73 (short pipe) performs an integral motion, and the inside of the cavity 72 Causes a pressure change in the air. Such a phenomenon is equivalent to the mass point-spring model of the dynamic system, assuming that the air in the opening hole 73 (short pipe) is a mass point and the pressure change due to the volume change of the air in the cavity 72 is a spring. Resonance (resonance) occurs with respect to the Helmholtz resonance frequency. That is, since the acoustic energy of this Helmholtz resonance frequency is confined in the cavity 72, the sound is reduced for the external space.

Here, the Helmholtz resonance frequency Fh (Hz) is calculated by the following equation.
Fh = C / 2π (Sb / (V1 · Tb)) 1/2
C: Speed of sound

  That is, the resonance frequency is changed by changing the opening area Sb, the length Tb (that is, the plate thickness of the portion of the housing 11 where the opening hole 73 is provided), and the volume V1 of the cavity 72 formed by the cavity forming member 72a. Fh, that is, the frequency of the sound to be reduced can be changed. Therefore, if the dimensions and the like of the above parts are designed so as to match the frequency at which the level becomes the highest among the sounds generated when the polygon mirror motor 2 is driven, the sounds generated by the polygon mirror motor 2 can be effectively obtained. Can be reduced.

  From the noise measurement results described above (see FIGS. 10 to 12), the polygon mirror motor sound is extracted as noise in the color mode, but the sound is not so noticeable as noise in the monochrome mode. . In such a case, the dimensions and the like of each part may be determined so that the Helmholtz resonance frequency matches the frequency of the highest level among the sounds generated by the polygon mirror motor in the color mode as described above. On the other hand, when the level of other frequencies is high in the monochrome mode, a Helmholtz resonator may be separately provided so that this frequency becomes the resonance frequency.

  In addition, a Helmholtz resonator may be provided for each corresponding frequency as described above, but a mechanism for changing the opening area Sb of the opening hole 73 in the color mode and the monochrome mode may be provided. . For example, by providing a lid member or the like that can be moved between a position where the opening 73 is blocked to some extent and a position where the opening hole 73 is not blocked, and moving the lid member according to the mode, the resonance frequency in each mode is changed to each mode. It may be varied so as to match the frequency at which the level sometimes increases.

(1-4) Reduction of Charging Sound Next, countermeasures for reducing charging noise will be described. The charged sound is sound generated as follows. That is, when the charging roller 36 charges the photosensitive drum 28 (see FIG. 3), the attractive force is generally generated between the surface of the charging roller 36 and the surface of the photosensitive drum 28 due to the AC component of the bias voltage. Repulsive forces act alternately, causing vibration between them. The sound radiated from the photosensitive drum 28 by this vibration is a charging sound, and the sound is a harsh pure sound having a high frequency, and generally includes an AC component frequency and an integral multiple frequency component (harmonic component). .

  Such measures for reducing the charging noise will be described with reference to FIGS. 40 and 41. FIG. As shown in FIG. 40, a vibration damping member 74 is disposed in the hollow portion of the photosensitive drum 28 that has been subjected to charging noise countermeasures. The damping member 74 has a hollow cylindrical base portion 75 extending in the axial direction of the photosensitive drum 28 and a plurality of blade portions 76 projecting radially from the base portion 75, and the central axis of the base portion 75 is photosensitive. It arrange | positions so that it may correspond with the center axis | shaft of the body drum 28 substantially.

  The tip of each blade portion 76 of the damping member is in pressure contact with the inner surface of the photosensitive drum 28, whereby the damping member 74 is held in the photosensitive drum 28. Here, it is preferable that the blade | wing part 76 is comprised with elastic materials, such as thermoplastic resin materials, such as rubber | gum, resin, or the material containing these, for example, the material containing urethane rubber, a polypropylene resin, a polyamide resin. By using an elastic material as the blade portion 76, the tip of the blade portion 76 is pressed against and held by the photosensitive drum 28 by its elastic force. This eliminates the need for an adhesive work or a position adjustment work (adjustment process) using an adhesive or the like, and facilitates the attachment work and the removal work.

  As described above, the vibration damping member 74 is arranged so that the blade portion 76 is in pressure contact with the inner surface side of the photosensitive drum 28, so that the vibration damping member 74 acts to suppress vibration of the photosensitive drum 28. Accordingly, it is possible to suppress vibration of the photosensitive drum 28 that occurs during charging by the charging roller 36 described above. In addition, since the member for suppressing the vibration of the photosensitive drum 28 is installed inside the photosensitive drum 28 as described above, it is not necessary to take measures such as newly taking a space for installing the damping member. .

  The means for suppressing the vibration of the photosensitive drum 28 to reduce the noise is not limited to the vibration damping member 74 having the above-described configuration, and measures such as fitting a metal column into the hollow portion of the photosensitive drum 28 are taken. Alternatively, a commercially available damping material (for example, Hama damper made by Yokohama Rubber Co., Ltd.) may be attached.

Regarding the Desktop (Desktop) Image Forming Apparatus As shown in FIG. 56, AC charging sound is also generated in the desktop (desktop) image forming apparatus. Also in this case, the above-mentioned means can suppress the generation of AC charging noise.

(2) Sharpness (High Frequency Component) Reduction Measures Regarding Image Forming Apparatus Having Multiple Modes (2-1) Reduction of Paper Sliding Sound Next, sharpness (high frequency component) reduction measures will be described. As a measure for reducing sharpness, there is a method of reducing paper sliding noise. Note that the paper sliding noise is a sound generated when the conveyed paper slides with a member or the like.

  As described above, the sheets stored in the first tray 9 or the second tray 10 of the image forming apparatus having a plurality of modes are fed out from each tray by the first sheet feeding unit 51 or the second sheet feeding unit 52 and relayed. It is conveyed to the position of the registration roller 7 by the roller 53 and the conveying roller 55 (see FIG. 7).

  Here, FIGS. 42A and 42B show a case where the paper stored in the first tray 9 or the second tray 10 is conveyed to form an image (during normal printing) and a case where printing is performed without conveying the paper (free). The result of frequency analysis (1/3 octave band analysis) by measuring the noise generated by the image forming apparatus is shown. FIG. 43 is a graph showing a difference in sound pressure level in each frequency band obtained from the noise during normal printing and free run shown in the analysis result.

  That is, the sound pressure level for each frequency band shown in FIG. 43 is a difference in noise content generated by the image forming apparatus due to whether or not the paper is sent out from the first tray 9 or the second tray 10 and conveyed. It means that the sound pressure level is increased in each frequency band as shown in FIG. 43 by conveying the paper.

  From the graph shown in FIG. 43, there are two differences of 3 (dB) or more between normal printing and free-running, a band centering on 200 to 250 Hz and a band of 3.15 kHz or more. . Note that the difference of 3 dB or more means that the acoustic energy is twice or more.

  Examining the above analysis results, it has been found that the band component centered at 200 to 250 Hz is caused by the sound generated when the sheet and the registration roller 7 collide. On the other hand, it has been found that the component in the frequency band of 3.15 kHz or more is caused by the sound generated when the sheet slides on the member or the like during sheet conveyance.

  Further, in the band centered on 12.5 kHz to 16 kHz, there is a difference of 7 (dB) or more, and this band has a great influence on the sharpness value. From this, it can be seen that reducing the sheet sliding noise is effective as a noise countermeasure. Hereinafter, a countermeasure for reducing the sliding noise of the sheet conveyed by the sheet feeding unit, the relay roller 53 and the conveying roller 55 will be described with reference to FIG.

  As shown in the figure, the transport roller 55 is a roller that has a plurality of rollers passing through its shaft, and includes a roller 55a and a roller 55b that are disposed to face each other across the paper transport path. Then, the sheet 55 conveyed along the conveyance path A (the sheet fed out from the first tray 9) or the sheet conveyed along the conveyance path B (the sheet fed out from the second tray 10) is the roller 55a. , 55b and conveyed toward the registration roller 7 by rollers 55a, 55b.

  Guide members 80, 81, 82 for conveying the paper along a predetermined path are disposed in the vicinity of the conveyance roller 55.

  The guide member 80 forms a space for guiding the paper conveyed along the conveyance path A together with the rollers 55a between the rollers 55a and 55b. The guide member 80 forms a space for guiding the sheet conveyed along the conveyance path B together with the guide member 81 toward the rollers 55a and 55b.

  A guide member made of a treadable sheet (for example, a polyester film (mylar sheet: product name)) extending in the paper conveyance direction (vertical direction in the drawing) is provided on the downstream side in the conveyance direction of the guide member 80 (upper side in FIG. 44). 77 is attached. The guide member 77 guides the sheet conveyed from the conveying paths A and B toward the rollers 55a and 55b.

  As shown in FIG. 45, at the position where the roller 55a is arranged so as not to intersect with the roller 55a at the front end portion of the guide member 77, a notch portion 77a is formed by cutting, etc. The tip is brought into contact with the roller 55a and 55b so as to be surely guided.

  Therefore, as shown in FIG. 46, the sheet from the conveyance path A is conveyed while sliding on the tip portion of the guide member 77. The conventional general guide member 77 is manufactured by shearing a flexible sheet into a predetermined shape, and a burr is usually provided at the tip portion (shear portion). It is very difficult to remove such burrs one by one, which requires cost and time. Therefore, normally, such an operation is not performed, and an awkward noise is generated by the sliding of the front end portion with the burr and the paper.

  Therefore, in this configuration, by employing the guide member 77 having the configuration shown in FIG. 47, it is possible to reduce annoying noise caused by the sliding of the paper and the leading end portion of the guide member 77 as described above. .

  As shown in FIG. 48, a guide member made of a conventional flexible sheet is a flexible sheet having a thickness t that has been sheared into a predetermined shape as a guide member 770. The part is a sheared part. On the other hand, in the configuration shown in FIG. 47, a flexible sheet having a thickness of t / 2 is folded to overlap two sheets so that the bent portion becomes the tip portion of the guide member 77. By adopting the guide member 77 having such a configuration, the leading end portion on which the sheet conveyed as described above slides is a bent portion, a portion not subjected to shearing, and a smooth R shape ( The end face has a curvature). Therefore, it is possible to reduce generation of annoying noise caused by burrs in the sheared portion as described above. Further, since the thickness of the two stacked sheets is the same as that of the conventional guide member 770, the required elastic force can be exhibited and the function as the guide member is not hindered.

Large-sized (console-type) image forming apparatus Next, an embodiment of reducing paper sliding noise will be described for a large-sized (console-type) image forming apparatus.

  First, the configuration of the conveyance path, which is the sound source of the paper sliding sound, and the cause of occurrence will be described. FIG. 73 is an explanatory diagram showing a detailed configuration of the rollers and guide plates of the main body vertical conveyance unit 580 in the image forming apparatus shown in FIG. That is, it is a cross-sectional view of a conveyance portion that guides conveyance from a paper feed tray and conveyance from an intermediate tray for double-sided copying in the direction of a registration roller. FIG. 74 is an explanatory diagram showing the relationship between the recording paper and the flexible sheet 59 when noise is not taken.

  In FIG. 73, reference numerals 550 and 551 denote rollers provided with a plurality of rollers on a shaft. The roller 550 and the roller 551 are paired to form a first transport roller pair that transports the recording paper, and rotates so as to transport the recording paper transported from the paper feed tray in the A direction shown in the figure. Reference numerals 552, 553, and 554 are rollers each having a plurality of rollers on a shaft in the form of a dumpling. The roller 552 and the roller 553 are paired to form a second transport roller pair that transports the recording paper, and rotates so as to transport the recording paper transported from the intermediate tray in the direction B shown in the drawing. Further, the roller 552 and the roller 554 are paired to form a third transport roller pair for transporting the recording paper, and the roller 552 and the roller 554 are rotated so as to transport in the C direction in the drawing, that is, the registration roller direction.

  Guide plates 555 and 556 are provided in the conveyance path of the first conveyance roller pair that is rotated so as to convey in the direction of arrow A, and the guide plates 555 and 556 have roller portions of the rollers 550 and 551. There is a hole to escape. Similarly, guide plates 557 and 558 are provided in the conveyance path of the second conveyance roller pair that rotates so as to convey in the direction of arrow B. The guide plates 557 and 558 are provided with rollers 552 and 553. There is a hole to escape the roller. Further, in the conveyance path of the third conveyance roller pair that rotates so as to convey in the direction of arrow C, there are extended portions of the guide plates 556 and 557, and these run away from the roller portions of the rollers 552 and 554. There is a hole in. That is, the conveyance force by the conveyance roller pair and the conveyance performance by the guide plate are ensured.

  A flexible sheet 559 extending in the recording paper conveyance direction is attached to the downstream end portion of the guide plate 555, and is provided so as to guide the recording paper. A conveyance path is formed so that the recording paper conveyed from the A direction is also conveyed in the C direction.

  Here, the recording paper conveyed in the B direction from the intermediate tray often has a downward curl, and in order to prevent the occurrence of folding or jamming (paper jam), a flexible sheet (specifically, Polyester film, product name: Mylar) 559 is bent in the right direction in the figure. Accordingly, the recording paper conveyed in the A direction from the paper feed tray enters between the rollers 552 and 554 by bypassing the front end of the flexible sheet 559.

  At this time, in the case of an unmeasured flexible sheet 559 as shown in FIG. 74, the recording paper is conveyed while sliding on the tip of the flexible sheet 559. However, since the surface of the recording paper has fiber irregularities, and the flexible sheet 59 is burred at the end surface by shearing processing, the irregularity proceeds on the fibers on the surface of the recording paper. The burr at the edge portion of 559 and the recording paper vibrate and generate a loud noise, resulting in noise. Note that it is very costly and time-consuming to remove burrs at the edge of the flexible sheet 59 one by one. Therefore, as shown below, countermeasures to reduce paper sliding noise were made by devising the flexible sheet 59.

  Examples of the flexible sheet 559 according to the embodiment of the present invention are shown in FIGS. This is the same as in the case of an image forming apparatus having a plurality of modes. 75 and 76, the leading edge of the flexible sheet 559 attached to the guide plate 555 slides when the recording paper conveyed from the direction of arrow A in FIG. In order to reduce (the surface of the paper has a certain degree of surface roughness and a sound containing a lot of high frequency components is generated when the edge is slid), a bent portion 559a is formed. The surface of the flexible sheet 559 is extremely smooth, and even if the bent portion 559a is provided, the smoothness is not lost.

(3) Impulsiveness (impact component) reduction countermeasure image forming apparatus having a plurality of modes In the image forming apparatus having the above-described configuration, the occurrence of impulsiveness is mostly caused by the fixing oil application sound (FIG. 10). To FIG. 12). In the image forming apparatus configured as described above, the fixing oil application sound is configured to drive the oil application unit 47 and contact the fixing belt 13 each time a sheet is conveyed in order to suppress an increase in oil consumption. Adopted (see FIG. 6). Since such a contact / separation sound generated every time the sheet is conveyed is generated shockingly, an unpleasant feeling is given.

  The noise problem due to the fixing oil application sound can be solved by using an oilless toner as a toner used for image formation. That is, since the oil-less toner includes wax in the toner, the separation between the fixing belt and the paper is good without performing the oil application operation as described above. For this reason, it is not necessary to use the oil application unit 47, and it is possible to prevent the generation of impact sound due to the contact and separation between the oil application unit 47 and the fixing belt 13 described above. When using oilless toner, it is necessary to modify the image forming process configuration of the photoconductor unit 3 and the like so as to be suitable for the oilless toner.

Large-sized (console type) image forming apparatus FIG. 77 is an explanatory diagram showing the configuration of the paper feed / drive system of the bank paper feed unit 570 in FIG. As shown in FIG. 55, the image forming apparatus according to this embodiment is configured to be capable of four-stage paper feeding, and the upper stage makes the conveyance path shorter, so that image formation becomes easier. Therefore, frequently used A4 size recording paper is set in the first level (the top level), and the B4 and A3 sizes, which are generally used less frequently, are set in the third and fourth levels (lower level). Often, this type of recording paper is loaded.

  In FIG. 77, grip rollers 567 are arranged in each of the four stages of paper feeding devices, and the recording paper fed from each paper feeding device goes upward via the grip rollers 567. The grip rollers 567 are respectively provided with driven rollers 569 so as to be pressurized by a pressure spring 570. The grip roller 567 and a paper separation mechanism (not shown) are driven by a bank motor 561 and convey the recording paper to the upper portion 500.

  An intermediate clutch 562, an intermediate clutch 563, an intermediate clutch 564, and an intermediate clutch 565 are provided on each shaft of the grip roller 567 from the top. These intermediate clutches 562 to 565 are constituted by electromagnetic clutches, and grip the driving force using the bank motor 551 as a driving source transmitted to the gears of the electromagnetic clutch via a timing belt and a gear train when the current is turned on / off. The roller 567 is rotated or non-rotated. This drive mechanism is provided in order to increase the processing efficiency by feeding the recording paper during image formation to control the space between the recording papers to the minimum. The relay sensor 566 is used for taking an image writing timing and for detecting a jam (paper jam).

  By the way, the main factor of the metal impact sound in the image forming apparatus is the operation sound of the intermediate clutch of the bank paper feeding unit 570 (the metallic collision sound that the disks are attracted by the electromagnet force when the clutch is turned on). I know that. These four intermediate clutches operate each time one sheet of recording paper is fed. In order to simplify the control, it is configured to operate even if paper is fed from any stage of the bank paper feeding unit 570. For this reason, even when paper is fed from the first stage of the bank paper feeding unit 570, the second to fourth stage grip rollers 67 that do not need to be driven are also driven. When paper is fed from the fourth stage (bottom 1), the recording paper is not conveyed upward unless all the grip rollers 567 are operated, so that all the intermediate clutches 562 to 565 need to be operated.

  However, as described above, frequently used paper is fed from the uppermost stage of the bank paper feeding unit 570 or the second tray. The third and fourth stages are used less frequently because they are loaded with recording paper having a low usage frequency.

  The metal impact noise is generated greatly when the intermediate clutches 562 to 565 of the bank paper feeding unit 570 are operated simultaneously. Therefore, when the first stage of the bank is used, only the intermediate clutch 562 is operated. The energy generation of the metal impact sound can be suppressed to ¼. In this way, by controlling so that only the intermediate clutch in the upper stage of the bank used for paper feeding is operated, it is possible to suppress noise and consumption of electric energy.

  FIG. 78 is a flowchart showing an example of control of the intermediate clutch of the bank paper feeding unit 570. First, it is determined whether or not the first stage paper feed (step S11). If the first stage paper feed, the intermediate clutch 562 is operated (step S12). In step S11, if it is not the first-stage paper feed, it is further determined whether or not it is the second-stage paper feed (step S13). If it is the second-stage paper feed, the intermediate clutches 562 and 563 are operated. (Step S14). In step S13, if it is not the second-stage paper feed, it is further determined whether or not it is the third-stage paper feed (step S15). If it is the third-stage paper feed, the intermediate clutches 562 to 564 are operated (step S13). S16) If the third-stage sheet feeding is not performed, that is, the fourth-stage sheet feeding (sheet feeding from the lowest tray), the intermediate clutches 562 to 565 are operated (step S17).

  In this way, by performing control to turn on only the necessary intermediate clutch and not operating the lower intermediate clutch that is less frequently used, it is possible to suppress the occurrence of metal impact noise.

  FIG. 79 is a graph showing changes in metal impact sound before and after improvement of control of the intermediate clutch. “Before improvement” means that four intermediate clutches are operated simultaneously. The metal impact sound improvement is obtained by operating only the first-stage intermediate clutch 562. According to this, the impact sound of the clutch is a high-frequency broadband noise of about 1 kHz to 20 kHz and contributes not only to impulsiveness but also to sharpness and loudness. In this way, the unpleasant sound can be reduced by suppressing the sound source of the impact sound.

  The above is a specific example of measures for reducing the discomfort index S.

  The inventor measures the sound generated by the image forming apparatus to which the above measures are taken under the same conditions as when the sound generated by the image forming apparatus before the measures are measured, and the effect of the measures is determined from the measurement results. investigated. Note that the measurement results to be compared below were obtained by collecting sound on the front side of the image forming apparatus when each image forming apparatus was operated at a color of 28 ppm.

  FIG. 49 shows the noise analysis results after the countermeasures. Comparing the analysis result after the countermeasure shown in the figure with the analysis result before the countermeasure (see FIG. 10), the paper feeding stepping motor noise is reduced by about 10 (dB), the charging noise is about 5 (dB), and the drum drive The motor noise is reduced by about 8 and the polygon mirror motor noise is also reduced by about 10 (dB). In addition, the fixing oil application sound was eliminated. From the above, it can be seen that the sound produced by each sound source can be reduced by taking the above measures.

  Table 22 shows a comparison result of the psychoacoustic parameter values obtained from the measurement results before and after the countermeasure and the sound quality evaluation values based on the sound quality evaluation formula (a).

  As can be seen from this table, the sound quality evaluation value after the countermeasure is “−0.519”, which is smaller than the allowable value “−0.497” of “color 28 ppm” shown in Table 14. Therefore, it can be said that the image forming apparatus has been remodeled so that the above measures hardly cause discomfort.

D. Application Example of the Present Invention Note that the present invention performs the sound quality evaluation of the image forming apparatus using the sound quality evaluation formula derived as described above, and the evaluation result (discomfort index S) satisfies the predetermined condition. It is to be able to provide. Therefore, as shown in FIG. 50, the present invention can be applied when developing and manufacturing a new product.

  Specifically, what configuration is adopted for each part of the image forming apparatus is designed so that the sound quality evaluation (discomfort index S) based on the sound quality evaluation formula satisfies a predetermined condition (S1: design process). Then, the image forming apparatus is manufactured according to the design contents in which the discomfort index S obtained from the sound generated by the image forming apparatus satisfies a predetermined condition (S2: manufacturing process). Through such a manufacturing process, an image forming apparatus that hardly generates unpleasant noise can be manufactured, and such an image forming apparatus can be provided to the user.

  The present invention can also be applied as a noise countermeasure for an image forming apparatus that has once been shipped to a user or a store. That is, the sound generated by the image forming apparatus already sold or the like is measured as described above, and the discomfort index S is derived from the measurement result using the sound quality evaluation formula. Then, it is determined whether or not the derived discomfort index S satisfies a predetermined condition. If it satisfies the condition, it is considered that almost no unpleasant noise is generated, and it is determined that no modification is necessary. On the other hand, when the derived discomfort index S does not satisfy the predetermined condition, various modifications as described above are performed on each part of the image forming apparatus so that the discomfort index S satisfies the predetermined condition. Accordingly, it is possible to provide an image forming apparatus that hardly generates unpleasant noise.

  As described above, the image forming apparatus, the manufacturing method of the image forming apparatus, the remodeling method of the image forming apparatus, and the sound quality evaluation method according to the present invention provide an image forming apparatus having a sound quality evaluation value or less that is acceptable to the user. Useful in case. In particular, by improving the sound quality so that it is lower than the permissible value of the sound quality corresponding to the operation speed and various modes, no matter what kind of device is used and which mode is used, it is uncomfortable with the device. It is suitable for various OA equipment, printers, home appliances, and other systems that can eliminate sound.

It is explanatory drawing which shows the structure of the digital color printer which has several operation mode concerning embodiment of this invention. It is explanatory drawing which shows the structure of the optical unit in FIG. FIG. 2 is an explanatory diagram illustrating a configuration of a photoconductor unit for each color in FIG. 1. FIG. 2 is an explanatory diagram illustrating a configuration of a driving unit of a photoconductor unit for each color in FIG. 1. FIG. 2 is an explanatory diagram illustrating a configuration of a fixing unit in FIG. 1. It is explanatory drawing which shows the structure of the oil application | coating unit in the fixing unit of FIG. It is explanatory drawing which shows the structure of the paper feed part in FIG. It is explanatory drawing which shows the structure of the 1st paper feed unit and the 2nd paper feed unit in the paper feed part of FIG. It is explanatory drawing which shows the sound collection position (measurement conditions) with respect to the image forming apparatus concerning embodiment of this invention. It is explanatory drawing which shows the analysis result at the time of picking up with the printing speed of color mode 28ppm. It is explanatory drawing which shows the analysis result at the time of picking up with the printing speed of color mode 18ppm. It is explanatory drawing which shows the analysis result at the time of picking up with the printing speed of 38 ppm in monochrome mode. It is a graph which shows the relationship between the sound pressure level level of the fixing oil application sound in a color mode 28ppm printing speed, and a subjective evaluation value. It is a graph which shows the relationship between the sound pressure level level and the subjective evaluation value of a paper sliding sound in the printing speed of color mode 28ppm. It is a graph which shows the relationship between the sound pressure level level of the drum stepping motor sound in the color mode 28ppm printing speed, and a subjective evaluation value. It is a graph which shows the relationship between the sound pressure level level of the color development drive sound in a color mode 28ppm printing speed, and a subjective evaluation value. It is a graph which shows the relationship between the sound pressure level level of the paper feed stepping motor sound in the printing speed of color mode 28ppm, and a subjective evaluation value. It is a graph which shows the relationship between the sound pressure level level of AC charging sound and subjective evaluation value in the printing speed of color mode 28ppm. It is a graph which shows the relationship between the sound pressure level level of the polygon motor sound in the color mode 28ppm printing speed, and a subjective evaluation value. It is a graph which shows the relationship between the sound pressure level level of the fixing oil application sound in the color mode 14ppm printing speed, and a subjective evaluation value. It is a graph which shows the relationship between the sound pressure level level of AC charging sound and drum stepping motor sound at the printing speed of 14 ppm in color mode, and the subjective evaluation value. It is a graph which shows the relationship between the sound pressure level level of the paper feeding stepping motor sound in the color mode of 14 ppm printing speed, and a subjective evaluation value. It is a graph which shows the relationship between the sound pressure level level and the subjective evaluation value of a paper sliding sound in the printing speed of 14 ppm in color modes. It is a graph which shows the relationship between the sound pressure level level of the development drive sound in monochrome 38ppm, and a subjective evaluation value. It is a graph which shows the relationship between the sound pressure level level of fixing oil application sound in monochrome 38ppm, and a subjective evaluation value. It is a graph which shows the relationship between the sound pressure level level of a paper sliding sound in the printing speed of monochrome 38ppm, and a subjective evaluation value. It is a graph which shows the relationship between the sound pressure level level of AC charging sound and drum stepping motor sound and the subjective evaluation value at a printing speed of 38 ppm in monochrome. It is a scatter diagram which shows the relationship between the actual value of the difference of a score, and the predicted value of the difference of a score. It is a graph which shows the relationship between the value estimated using the sound quality evaluation formula (a) for every eight experiments, and an actual measurement value. It is a graph which approximates the relationship between ppm value and discomfort tolerance according to the result of Table 21. 22 is a graph showing an approximation of a relationship between an image forming speed (v) and an acceptable discomfort value according to the results of Table 21. It is explanatory drawing which shows the structure of the drum drive mechanism before remodeling. It is explanatory drawing which shows the attachment structure of the drive motor and bracket in the drum drive mechanism before remodeling. It is explanatory drawing which shows the attachment structure of the drive motor and bracket in the drum drive mechanism after remodeling. It is explanatory drawing which shows the structure of the drum drive mechanism after remodeling. It is explanatory drawing which shows the detailed structure of the drum drive mechanism after remodeling. It is explanatory drawing which shows the motion of the rotor for every step angle in the stepping motor for paper feed drive. It is explanatory drawing which shows the structure and sequence of macro step drive in the stepping motor for paper feed drive. It is explanatory drawing which shows the state which mounts a Helmholtz resonator to a polygon mirror motor. It is explanatory drawing which shows the state of a damping member and the periphery mechanism in the photoconductive drum in a countermeasure against a charging noise. FIG. 41 is an explanatory diagram showing the shape of the vibration damping member in FIG. 40 and the state of insertion into the photosensitive drum. It is a graph which shows the state of the sound pressure level at the time of carrying out free run without performing printing while feeding from the 1st tray / the 2nd tray and performing normal printing. It is a graph which shows the sound pressure level difference of each frequency band obtained from the analysis result of FIG. It is explanatory drawing which shows the structure of a paper feed / relay / conveyance system. It is explanatory drawing which shows the state of the conveyance roller and guide member in FIG. FIG. 46 is an explanatory diagram illustrating a sheet conveyance state by the guide member of FIGS. 44 and 45. It is explanatory drawing which shows the structure of the guide member after a countermeasure, and the contact state of a paper. It is explanatory drawing which shows the structure of the guide member before a countermeasure, and the contact state of a paper. It is explanatory drawing which shows the sound pressure level of each drive part after modifying each drive part. It is a flowchart which shows the manufacturing step concerning embodiment of this invention. It is explanatory drawing which shows the structure of the laser printer (desktop type) concerning embodiment of this invention. FIG. 52 is an explanatory diagram showing a configuration of a process cartridge in FIG. 51. FIG. 52 is an explanatory diagram illustrating a configuration of a charging roller in FIG. 51. It is explanatory drawing which shows the structure of the image forming apparatus (console type) of the medium speed machine concerning embodiment of this invention. It is explanatory drawing which shows the structure of the image forming apparatus (console type) of the high speed machine concerning embodiment of this invention. FIG. 52 is an explanatory diagram showing a noise analysis result in the desktop laser printer of FIG. 51. FIG. 55 is an explanatory diagram showing the analysis result of noise in the image forming apparatus of the medium speed machine of FIG. 54. FIG. 55 is an explanatory diagram showing the analysis result of noise in the image forming apparatus of the high speed machine of FIG. 54. It is a graph which shows the relationship between the sound pressure level level of the main motor sound in a monochrome 20ppm printing speed, and a subjective evaluation value. It is a graph which shows the relationship between the sound pressure level level of a metal impact sound in a monochrome 20ppm printing speed, and a subjective evaluation value. It is a graph which shows the relationship between the sound pressure level level of AC charging sound in a monochrome 20ppm printing speed, and a subjective evaluation value. It is a graph which shows the relationship between the sound pressure level level and the subjective evaluation value of the supply impact sound at the monochrome 27 ppm printing speed. It is a graph which shows the relationship between the sound pressure level level and the subjective evaluation value of the paper feeding sound at a monochrome 27 ppm printing speed. It is a graph which shows the relationship between the sound pressure level level of a paper sliding sound and the subjective evaluation value in the monochrome 27ppm printing speed. It is a graph which shows the relationship between the sound pressure level level of a metal impact sound in a monochrome 27ppm printing speed, and a subjective evaluation value. It is a graph which shows the relationship between the sound pressure level level of the motor drive system sound in a monochrome 27ppm printing speed, and a subjective evaluation value. It is a graph which shows the relationship between the sound pressure level level of a metal impact sound in a monochrome 65ppm printing speed, and a subjective evaluation value. It is a graph which shows the relationship between the sound pressure level level and the subjective evaluation value of a paper sliding sound in monochrome 65 ppm printing speed. It is a graph which shows the relationship between the sound pressure level level of a paper drama sound and a subjective evaluation value in the monochrome 65ppm printing speed. It is a graph which shows the relationship between the sound pressure level level of a bank motor sound in the monochrome 65ppm printing speed, and a subjective evaluation value. It is a graph which shows the relationship between the sound pressure level level of the developing motor sound in the monochrome 65ppm printing speed, and a subjective evaluation value. It is a graph which shows the relationship between the sound pressure level level of the main motor sound in a monochrome 65ppm printing speed, and a subjective evaluation value. FIG. 56 is an explanatory diagram showing a detailed configuration of a roller and a guide plate of the main body vertical conveyance unit in FIG. 55. It is explanatory drawing which shows the contact state of the paper and a flexible sheet at the time of noise non-measure. It is explanatory drawing which shows the contact state of the paper and a flexible sheet after noise countermeasures. It is explanatory drawing which shows the shape etc. of the flexible sheet | seat at the time of noise countermeasures. FIG. 56 is an explanatory diagram showing a configuration of a paper feed / drive system of the bank paper feed unit in FIG. 55. 56 is a flowchart showing an example of control of an intermediate clutch of the bank paper feeding unit in FIG. 55. 56 is a graph showing changes in metal impact sound before and after the improvement of the control of the intermediate clutch of the bank paper feeding unit in FIG. 55.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical unit 2 Polygon mirror motor 3 Photosensitive unit 4 Developing unit 28 Photosensitive drum 41 Color drum drive motor 42 Black drum drive motor 46 Fixing unit 56 Stepping motor 60 Anti-vibration rubber mount 71 Helmholtz resonator 74 Damping member 77 Guide member 110 Paper Feed Unit 303 Process Cartridge 559 Flexible Sheet 562-565 Intermediate Clutch 570 Bank Paper Feed Unit

Claims (29)

An image forming apparatus for forming an image on a recording paper,
A sound emitted from the image forming apparatus when forming an image on the recording paper is picked up at a position separated from the end face of the image forming apparatus by a predetermined distance, and an acoustic physical quantity and an image forming speed obtained from the collected sound are collected. An image forming apparatus characterized by calculating a discomfort index S using a value and setting the discomfort index S to a predetermined value or less. The acoustic physical quantity is a sound pressure level value, a loudness value, a sharpness value, a tonality value, and an impulsiveness value obtained by collecting sound at a position approximately 1 m away from the end face of the image forming apparatus, and the image forming speed is ppm. The discomfort index S is calculated by the equation (a), and the discomfort index S satisfies the condition (b). The image forming apparatus described.
S = A × (sound pressure level value) + B × (loudness value) + C × (sharpness value)
+ D x (Tonality value) + E x (Impulsiveness value) + F
0.037865 ≦ A ≦ 0.066678
0.126588 ≦ B ≦ 0.189486
0.367910 ≦ C ≦ 0.459389
2.532697 ≦ D ≦ 3.402664
1.132176 ≦ E ≦ 1.450574
−7.246314 ≦ F ≦ −4.7741981
(A)
S ≦ 0.4818Ln (ppm) −1.586 • (b)
14 ≦ ppm ≦ 65 The acoustic physical quantity is a sound pressure level value, a loudness value, a sharpness value, a tonality value, and an impulsiveness value obtained by collecting sound at a position approximately 1 m away from the end face of the image forming apparatus, and the image forming speed is ppm. The discomfort index S is calculated by the equation (c), and the discomfort index S satisfies the condition (b). The image forming apparatus described.
S = A × (sound pressure level value) + B × (loudness value) + C × (sharpness value)
+ D x (Tonality value) + E x (Impulsiveness value) + F
A = 0.0522715
B = 0.1580369
C = 0.41366496
D = 2.96777803
E = 1.291173747
F = −5.999889619
(C)
S ≦ 0.4818Ln (ppm) −1.586 • (b)
14 ≦ ppm ≦ 65 The acoustic physical quantity is a sound pressure level value, a loudness value, a sharpness value, a tonality value, and an impulsiveness value obtained by collecting sound at a position approximately 1 m away from the end face of the image forming apparatus, and the image forming speed is v : Mm / s value,
2. The image forming apparatus according to claim 1, wherein the discomfort index S is calculated by the formula (a), and the discomfort index S satisfies the condition (d).
S = A × (sound pressure level value) + B × (loudness value) + C × (sharpness value)
+ D x (Tonality value) + E x (Impulsiveness value) + F
0.037865 ≦ A ≦ 0.066678
0.126588 ≦ B ≦ 0.189486
0.367910 ≦ C ≦ 0.459389
2.532697 ≦ D ≦ 3.402664
1.132176 ≦ E ≦ 1.450574
−7.246314 ≦ F ≦ −4.7741981
(A)
S ≦ 0.4248Ln (v) −2.4301 (d)
62.5 ≦ v ≦ 362 The acoustic physical quantity is a sound pressure level value, a loudness value, a sharpness value, a tonality value, and an impulsiveness value obtained by collecting sound at a position approximately 1 m away from the end face of the image forming apparatus, and the image forming speed is v : Mm / s value,
2. The image forming apparatus according to claim 1, wherein the discomfort index S is calculated by the formula (c), and the discomfort index S satisfies the condition (d).
S = A × (sound pressure level value) + B × (loudness value) + C × (sharpness value)
+ D x (Tonality value) + E x (Impulsiveness value) + F
A = 0.0522715
B = 0.1580369
C = 0.41366496
D = 2.96777803
E = 1.291173747
F = −5.999889619
(C)
S ≦ 0.4248Ln (v) −2.4301 (d)
62.5 ≦ v ≦ 362   A plurality of image forming apparatuses having different image forming speeds or driving units or operations of image forming means, wherein the discomfort index S satisfies the condition regardless of the image forming speed and the image forming mode. Item 6. The image forming apparatus according to any one of Items 1 to 5.   The sound collection position is a neighbor position defined by ISO (International Organization for Standardization) 7779, and the discomfort index S calculated from the sound collection result of sound in the direction of at least the front surface of the apparatus (surface with the operation unit). The image forming apparatus according to claim 1, wherein the condition satisfies the condition.   The sound collection position is a neighbor position defined in ISO (International Organization for Standardization) 7779, and the average of the discomfort index S calculated from each of the sound collection results of the sound in the four directions before and after the device. The image forming apparatus according to claim 1, wherein a value satisfies the condition.   The sound collection position is a neighbor position defined in ISO (International Organization for Standardization) 7779, and at least the discomfort index S calculated from the sound collection results of the sound in any one direction of the front, rear, left and right of the device. The image forming apparatus according to claim 1, wherein the condition is satisfied.   The sound collection position is a neighbor position defined by ISO (International Organization for Standardization) 7779, and all the uncomfortable indices S calculated from the sound collection results of the sound in the four directions of the front, rear, left and right of the device. The image forming apparatus according to claim 1, wherein the condition satisfies the condition.   The image forming apparatus according to claim 1, further comprising a sound reduction unit that reduces a sound generated by the apparatus during image formation on the recording paper. Furthermore, a stepping motor that drives a predetermined portion during image formation on the recording paper, and a bracket member that holds the stepping motor,
The image forming apparatus according to claim 11, wherein the sound reducing unit includes an elastic body disposed between the stepping motor and the bracket member. Furthermore, a stepping motor for driving a predetermined part at the time of image formation on the recording paper is provided,
The image forming apparatus according to claim 11, wherein the sound reduction unit includes a drive control unit that micro-steps the stepping motor. Furthermore, a motor for driving a predetermined part at the time of image formation on the recording paper is provided,
The image forming apparatus according to claim 11, wherein the sound reduction unit includes a Helmholtz resonator disposed in the vicinity of the motor. Furthermore, a cylindrical image carrier having a hollow portion, and charging means for charging the surface of the image carrier,
The image forming apparatus according to claim 11, wherein the sound reduction unit includes a vibration damping member that suppresses vibration of the image carrier in a hollow portion of the image carrier.   And a guide member that is made of a flexible sheet that guides the recording paper along a predetermined transport path, and that is in contact with the transported recording paper, and is a bent portion of the flexible sheet. The image forming apparatus according to claim 11.   12. The image forming apparatus according to claim 11, wherein the toner used for image formation on the recording paper is a toner containing wax.   The sound reduction means is a paper feed and transport control means for controlling the operation of an electromagnetic clutch provided in each of the paper feed and transport paths having a plurality of paper feed stages to be an electromagnetic clutch that is equal to or higher than the paper feed stage to be used. The image forming apparatus according to claim 11. A method of manufacturing an image forming apparatus for forming an image on a recording paper,
The sound pressure level value of the acoustic physical quantity obtained from the sound generated by the image forming apparatus when the image is formed on the recording paper picked up at the sound collecting position approximately 1 m away from the end face of the image forming apparatus to be manufactured. , Loudness value, sharpness value, tonality value, impulsiveness value, and output value (ppm) of the recording paper (A4 size lateral direction) per minute, and the discomfort index S calculated by the following equation (a) A design step of designing each part of the apparatus so as to satisfy the following condition (b):
S = A × (sound pressure level value) + B × (loudness value) + C × (sharpness value)
+ D x (Tonality value) + E x (Impulsiveness value) + F
0.037865 ≦ A ≦ 0.066678
0.126588 ≦ B ≦ 0.189486
0.367910 ≦ C ≦ 0.459389
2.532697 ≦ D ≦ 3.402664
1.132176 ≦ E ≦ 1.450574
−7.246314 ≦ F ≦ −4.7741981
(A)
S ≦ 0.4818Ln (ppm) −1.586 • (b)
14 ≦ ppm ≦ 65
A manufacturing step of manufacturing the image forming apparatus according to the design content made by the design step;
A method for manufacturing an image forming apparatus, comprising: A method of manufacturing an image forming apparatus for forming an image on a recording paper,
A sound pressure level value of an acoustic physical quantity obtained from a sound emitted by the apparatus when image formation is performed on the recording paper, which is collected at a sound collection position approximately 1 m away from an end face of the image forming apparatus to be manufactured; Using the loudness value, sharpness value, tonality value, impulsiveness value and the output value (ppm) of the recording paper (A4 size lateral direction) per minute, the discomfort index S calculated by the following equation (c) is A design step of designing each part of the apparatus so as to satisfy the following condition (b):
S = A × (sound pressure level value) + B × (loudness value) + C × (sharpness value)
+ D x (Tonality value) + E x (Impulsiveness value) + F
A = 0.0522715
B = 0.1580369
C = 0.41366496
D = 2.96777803
E = 1.291173747
F = −5.999889619
(C)
S ≦ 0.4818Ln (ppm) −1.586 • (b)
14 ≦ ppm ≦ 65
A manufacturing step of manufacturing the image forming apparatus according to the design content made by the design step;
A method for manufacturing an image forming apparatus, comprising: A method of manufacturing an image forming apparatus for forming an image on a recording paper,
The sound pressure level of the acoustic physical quantity obtained from the sound generated by the image forming apparatus when the image is formed on the recording paper, which is collected at a sound collecting position approximately 1 m away from the end face of the image forming apparatus to be manufactured. Value, loudness value, sharpness value, tonality value, impulsiveness value, and image formation speed (v: mm / s) on the recording paper, and the discomfort index S calculated by the following equation (a) is A design step of designing each part of the apparatus so as to satisfy the condition (d)
S = A × (sound pressure level value) + B × (loudness value) + C × (sharpness value)
+ D x (Tonality value) + E x (Impulsiveness value) + F
0.037865 ≦ A ≦ 0.066678
0.126588 ≦ B ≦ 0.189486
0.367910 ≦ C ≦ 0.459389
2.532697 ≦ D ≦ 3.402664
1.132176 ≦ E ≦ 1.450574
−7.246314 ≦ F ≦ −4.7741981
(A)
S ≦ 0.4248Ln (v) −2.4301 (d)
62.5 ≦ v ≦ 362
A manufacturing step of manufacturing the image forming apparatus according to the design content made by the design step;
A method for manufacturing an image forming apparatus, comprising: A method of manufacturing an image forming apparatus for forming an image on a recording paper,
The sound pressure level value of the acoustic physical quantity obtained from the sound generated by the image forming apparatus when the image is formed on the recording paper picked up at the sound collecting position approximately 1 m away from the end face of the image forming apparatus to be manufactured. , Loudness value, sharpness value, tonality value, impulsiveness value, and image formation speed (v: mm / s) on the recording paper, the discomfort index S calculated by the following equation (c) is A design step of designing each part of the apparatus to satisfy the condition (d);
S = A × (sound pressure level value) + B × (loudness value) + C × (sharpness value)
+ D x (Tonality value) + E x (Impulsiveness value) + F
A = 0.0522715
B = 0.1580369
C = 0.41366496
D = 2.96777803
E = 1.291173747
F = −5.999889619
(C)
S ≦ 0.4248Ln (v) −2.4301 (d)
62.5 ≦ v ≦ 362
A manufacturing step of manufacturing the image forming apparatus according to the design content made by the design step;
A method for manufacturing an image forming apparatus, comprising: A method of remodeling an image forming apparatus for forming an image on a recording paper,
A sound collecting step for collecting sound generated by the image forming apparatus when image formation is performed on the recording paper at a sound collecting position approximately 1 m away from an end surface of the image forming apparatus to be modified;
The sound pressure level value, loudness value, sharpness value, tonality value, impulsiveness value of the acoustic physical quantity obtained from the sound collection result in the sound collection step, and the output of the recording paper (A4 size lateral direction) per minute A remodeling step that modifies the configuration of the apparatus so that the discomfort index S calculated by the following equation (a) satisfies the following condition (b) using a numerical value (ppm):
A method for remodeling an image forming apparatus, comprising:
S = A × (sound pressure level value) + B × (loudness value) + C × (sharpness value)
+ D x (Tonality value) + E x (Impulsiveness value) + F
0.037865 ≦ A ≦ 0.066678
0.126588 ≦ B ≦ 0.189486
0.367910 ≦ C ≦ 0.459389
2.532697 ≦ D ≦ 3.402664
1.132176 ≦ E ≦ 1.450574
−7.246314 ≦ F ≦ −4.7741981
(A)
S ≦ 0.4818Ln (ppm) −1.586 • (b)
14 ≦ ppm ≦ 65 A method of remodeling an image forming apparatus for forming an image on a recording paper,
A sound collecting step for collecting sound generated by the image forming apparatus when image formation is performed on the recording paper at a sound collecting position approximately 1 m away from an end surface of the image forming apparatus to be modified;
The sound pressure level value, loudness value, sharpness value, tonality value, impulsiveness value of the acoustic physical quantity obtained from the sound collection result in the sound collection step, and the output of the recording paper (A4 size lateral direction) per minute A remodeling step that modifies the configuration of the device so that the discomfort index S calculated by the following equation (c) satisfies the following condition (b) using a numerical value (ppm):
A method for remodeling an image forming apparatus, comprising:
S = A × (sound pressure level value) + B × (loudness value) + C × (sharpness value)
+ D x (Tonality value) + E x (Impulsiveness value) + F
A = 0.0522715
B = 0.1580369
C = 0.41366496
D = 2.96777803
E = 1.291173747
F = −5.999889619
(C)
S ≦ 0.4818Ln (ppm) −1.586 • (b)
14 ≦ ppm ≦ 65 A method of remodeling an image forming apparatus for forming an image on a recording paper,
A sound collecting step for collecting sound generated by the image forming apparatus when image formation is performed on the recording paper at a sound collecting position approximately 1 m away from an end surface of the image forming apparatus to be modified;
A sound pressure level value, a loudness value, a sharpness value, a tonality value, an impulsiveness value, and an image formation speed (v: mm / s) of the recording paper, which are obtained from the sound collection result in the sound collection step. Remodeling step for modifying the configuration of the apparatus so that the discomfort index S calculated by the following equation (a) satisfies the following condition (d):
A method for remodeling an image forming apparatus, comprising:
S = A × (sound pressure level value) + B × (loudness value) + C × (sharpness value)
+ D x (Tonality value) + E x (Impulsiveness value) + F
0.037865 ≦ A ≦ 0.066678
0.126588 ≦ B ≦ 0.189486
0.367910 ≦ C ≦ 0.459389
2.532697 ≦ D ≦ 3.402664
1.132176 ≦ E ≦ 1.450574
−7.246314 ≦ F ≦ −4.7741981
(A)
S ≦ 0.4248Ln (v) −2.4301 (d)
62.5 ≦ v ≦ 362 A method of remodeling an image forming apparatus for forming an image on a recording paper,
A sound collecting step for collecting sound generated by the image forming apparatus when image formation is performed on the recording paper at a sound collecting position approximately 1 m away from an end surface of the image forming apparatus to be modified;
A sound pressure level value, a loudness value, a sharpness value, a tonality value, an impulsiveness value, and an image formation speed (v: mm / s) of the recording paper, which are obtained from the sound collection result in the sound collection step. Remodeling step for modifying the configuration of the apparatus so that the discomfort index S calculated by the following equation (c) satisfies the following condition (d):
A method for remodeling an image forming apparatus, comprising:
S = A × (sound pressure level value) + B × (loudness value) + C × (sharpness value)
+ D x (Tonality value) + E x (Impulsiveness value) + F
A = 0.0522715
B = 0.1580369
C = 0.41366496
D = 2.96777803
E = 1.291173747
F = −5.999889619
(C)
S ≦ 0.4248Ln (v) −2.4301 (d)
62.5 ≦ v ≦ 362 A method for evaluating a sound generated by an image forming apparatus that forms an image on a recording paper during image formation,
The sound produced at the time of image formation is evaluated by the paired comparison method, and the multiple regression analysis is performed by using the difference of the score by the evaluation as the objective variable and the difference of the psychoacoustic parameter value as the explanatory variable. The following formula (e) for the difference is derived,

The sound quality evaluation for predicting the evaluation value of the discomfort of the sound by substituting the average value of the psychoacoustic parameter values used in the derivation of the above equation into the above equation (e) and defining α = 0 at that time A sound quality evaluation method characterized by deriving an expression and performing sound quality evaluation using the derived sound quality evaluation expression. A method of manufacturing an image forming apparatus for forming an image on a recording paper,
The sound produced at the time of image formation is evaluated by the paired comparison method, and further, a multiple regression analysis is performed using the difference in the score of the evaluation as an objective variable and the difference in psychoacoustic parameter values as an explanatory variable. The following formula (e) regarding the difference in evaluation is derived,

The sound quality evaluation for predicting the evaluation value of the discomfort of the sound by substituting the average value of the psychoacoustic parameter values used in the derivation of the above equation into the above equation (e) and defining α = 0 at that time An image characterized by deriving an expression, designing each part of the apparatus so that the sound quality evaluation based on the derived sound quality evaluation expression satisfies a predetermined condition, and manufacturing an image forming apparatus according to the design content Manufacturing method of forming apparatus. A method of remodeling an image forming apparatus for forming an image on a recording paper,
The sound produced at the time of image formation is evaluated by the paired comparison method, and further, a multiple regression analysis is performed using the difference in the score of the evaluation as an objective variable and the difference in psychoacoustic parameter values as an explanatory variable. The following formula (e) regarding the difference in evaluation is derived,

The sound quality evaluation for predicting the evaluation value of sound discomfort by substituting the average value of the psychoacoustic parameter values used in the derivation of the above equation into the above equation (e) and defining α = 0 at that time The sound quality evaluation of the image forming apparatus to be modified is performed using the derived sound quality evaluation formula, and the configuration of the image forming apparatus to be modified is further modified according to the sound quality evaluation result. A method for remodeling an image forming apparatus.

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