JP2001290327A - Color image forming equipment - Google Patents

Abstract

(57) Abstract: An object of the present invention is to provide a color image forming apparatus that appropriately corrects a position shift while improving image forming efficiency. A color image forming apparatus 1 forms toner images of different colors based on image data in image forming units 30Y to 30Bk of a plurality of colors arranged along a conveyance belt 21 in continuous printing. A color image is formed by sequentially transferring the image on the recording paper 12 conveyed on the conveying belt 21 at a sheet interval shorter than one circumference of the photoconductors 31Y to 31Bk. If the number of sheets to be aligned exceeds, the conveyance interval of the recording paper 12 is set to the photosensitive member 31Y only during the timing of forming the position detection pattern.
Is changed to a paper interval longer than one circumference of ~ 31Bk, and the position detection pattern is conveyed by the image forming units 30Y, 30M, 30C, and 30Bk between the recording papers 12 at the changed paper interval. It is formed on the belt 21 and performs a position shift correction process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming apparatus, and more particularly, to a color image forming apparatus for forming toner images of different colors on a transfer paper by arranging a plurality of image forming sections along a conveyor belt. More particularly, the present invention relates to an electrophotographic color image forming apparatus that appropriately corrects misregistration while forming a color image by superimposing images while improving image forming efficiency.

[0002]

2. Description of the Related Art Conventionally, as a so-called tandem type color image forming apparatus for forming a full-color image by superposing images by juxtaposing a plurality of writing units and image forming units of an electrophotographic system, for example, There are full-color copiers and the like. Such a full-color copying machine is provided with an image forming station for forming an image of each color of cyan, magenta, yellow, and black. The image forming station of each color is provided with a writing unit and an image forming unit, and image data of each color is provided. The latent image is formed by irradiating the laser modulated by the writing unit to the photoconductor of the image forming unit to form a latent image, and the image forming unit of each color supplies the toner of each color to the photoconductor on which the latent image is formed. Then, the toner images of each color are developed. The image forming units for the respective colors sequentially transfer the toner images on the photoreceptor onto transfer paper conveyed on the conveyor belt, and form a color image by superimposing the toner images of the respective colors on the transfer paper.

In a color image forming apparatus having a plurality of image forming stations as described above, each image forming apparatus is compared with a color image forming apparatus having only one photoreceptor called a one-drum type and forming a color image. Because different toner images are sequentially superimposed on the same surface of the same transfer paper at the forming station to form a color image, if the position of the transferred image on the transfer paper at each image forming station is shifted, each image forming station The image intervals to be formed are shifted or overlap, and in the case of a color image,
Differences in color and misregistration result in poor image quality.

[0004] The positional deviation may be caused by an assembling error in the writing optical system, an error in mounting each unit to the main body of the color image forming apparatus, an error in mounting the photosensitive member to the main body of the color image forming apparatus, or the like. And the parallel positional shift that occurs when the position of the scanning line is shifted in parallel to the reference position and the four-color image is shifted vertically or horizontally as a whole. is there. Of these misalignments, the misalignment of the inclination is corrected by finely adjusting the position of the reflection mirror of the writing unit, and the parallel misalignment is used to adjust the writing start timing in the main scanning direction or the sub-scanning direction. By doing so, correction can be performed. Further, the length of the image in the main scanning direction can be adjusted by changing the frequency of the writing pixel, that is, by adjusting the magnification error.

[0005] Even if the color image forming apparatus is initially adjusted, such misalignment only occurs due to replacement of the image forming unit, maintenance of the color image forming apparatus, transportation of the color image forming apparatus, and the like. In addition, the error may fluctuate over time due to the temperature expansion of the mechanism after the formation of a plurality of images.

Therefore, conventionally, an electrostatic latent image is formed by irradiating a laser beam on at least two photosensitive members, and the electrostatic latent image is developed by a toner of each color, and fed by a paper feeding unit. Transfer means for superimposing and transferring, from each recording means, an image obtained by the recording means onto a recording medium conveyed onto the transfer means.
Pattern image forming means for forming a predetermined pattern image for detecting registration deviation of each recording means in two directions, a conveyance direction on the transfer means and a direction substantially perpendicular to the conveyance direction; Pattern reading means for reading a pair of predetermined pattern images formed on the transfer means at predetermined timing by means, and storage means for storing pattern image data read at predetermined timing by the pattern reading means; Calculating means for performing a predetermined operation on the pattern image data stored in the storage means in the main scanning direction and the sub-scanning direction to calculate a center position of each pattern image; and a center of each pattern image calculated by the calculating means. The position of the scanning mirror arranged in the optical path of the laser beam is registered based on the position. First control means for performing positioning control so that the patterns coincide with each other, and controlling the image writing timing of the laser beam in the main scanning direction and the sub-scanning direction based on the center position of each pattern image calculated by the calculation means. And a second control unit for performing a predetermined pattern between the recording media each time the number of fed recording media exceeds a preset number during continuous printing of a plurality of sheets. An image is formed, and each time the pattern reading unit reads the formed pattern image and stores the pattern image data in the storage unit, the registration correction of each recording unit is performed by the first and second control units. An image forming apparatus characterized by the following has been proposed (see JP-A-7-234612).

That is, in this image forming apparatus, when the number of sheets fed exceeds a predetermined number during continuous printing of a plurality of sheets, an alignment pattern is formed between the recording media to correct the positional deviation. .

Further, the present applicant has previously disclosed a plurality of photosensitive members, optical writing means for writing information of different colors on each of the photosensitive members, and visualization of the written information with developers of different colors. And an image forming apparatus that sequentially obtains a color image by sequentially transferring the visual images formed on each photoconductor onto the same transfer paper conveyed by a transfer belt.
A simple misregistration detection pattern image forming means for forming, for each color, a plurality of simple misregistration detection pattern images arranged in a line in the main scanning direction between transfer papers conveyed by the transfer belt on the transfer belt; And positional deviation amount detection for forming a plurality of sets of positional deviation amount detection pattern images arranged in the main scanning direction and the sub-scanning direction while being displaced in the main scanning direction for each color along the main scanning direction. A pattern image forming unit, a detection unit that detects the displacement amount detection pattern image and the simple displacement detection pattern image that move together with the transfer belt, and detection of the detection unit that detects the simple displacement detection pattern image A simple position shift determining means for determining whether the position shift amount of the simple position shift detection pattern image is within an allowable range based on a result; A position shift amount detection pattern image formation start unit that starts formation of a position shift amount detection pattern image by the position shift amount detection pattern image forming unit when the simple position shift determination unit determines that the position shift is equal to or more than the allowable range; An image forming apparatus, comprising: a displacement amount detection unit that detects a displacement amount of the displacement amount detection pattern image based on a detection result of the detection unit that detects the displacement amount detection pattern image. Has been proposed (see Japanese Patent Application Laid-Open No. 10-73979).

That is, in this image forming apparatus, a simple positional shift pattern is formed between recording media to perform positional deviation correction.

[0010]

However, in the image forming apparatus described in the above-mentioned publication, it is necessary to improve the position adjustment accurately without lowering the productivity (efficiency) of the color image forming apparatus. Was needed.

That is, in order to accurately correct the positional deviation, it is necessary to accurately detect the positional deviation detection pattern. However, if the photosensitive member is eccentric, the amount of positional deviation at each position in the transport direction of the recording medium is reduced. Fluctuates, the fluctuation of the positional deviation amount makes the detection of the positional deviation detection pattern inaccurate, and the accuracy of calculating the positional deviation amount itself decreases.

In order to prevent the calculation accuracy of the displacement amount from deteriorating, the displacement detection pattern is formed to have a circumference of the photosensitive member or an integral multiple of the circumference of the photosensitive member. It is necessary to calculate a positional shift amount by detecting a positional shift detection pattern having an integral multiple of one circumference.

However, since the image forming apparatus described in Japanese Patent Application Laid-Open No. 7-234612 does not have a means for changing the interval between recording media during continuous printing, it is difficult to accurately detect the amount of misalignment. In order to form a misregistration detection pattern of one circumference of the photoconductor or an integral multiple of one circumference,
It is necessary to set the interval between the recording media at the time of continuous printing to be longer than one circumference of the photoconductor or an integral multiple of one circumference.
There is a problem that the interval between the recording media during continuous printing is too large, the printing speed is reduced, and the productivity is deteriorated.

In the image forming apparatus described in Japanese Patent Application Laid-Open No. 10-73979, a simple pattern is formed as a misregistration detection pattern formed between recording media to prevent a decrease in productivity. Since the simple misalignment pattern is formed, it is necessary to improve the method for accurately detecting misalignment.

Therefore, according to the first aspect of the present invention, a plurality of transfer papers, which are fed from a paper supply means at a predetermined short paper interval during continuous printing, are sequentially transported on a transport belt, and a plurality of transfer papers are arranged along the transport belt. Each of the image forming units creates a toner image of a different color based on the image data and sequentially transfers the toner images onto transfer paper to form a color image. When forming a misregistration detection pattern on the transport belt by each image forming means, and performing a misregistration correction process of detecting the misregistration detection pattern and correcting the misalignment,
At the time of continuous printing, if the number of continuous prints exceeds a preset reference number, the paper interval to be sent from the paper feeding unit onto the conveyor belt is changed to a paper interval longer by a predetermined amount than the paper interval during normal image formation, A position determined based on the number of continuous prints by forming a position shift detection pattern on each of the image forming units on the transport belt between the transfer sheets at the changed sheet interval and performing a position shift correction process. Only at the time of forming the misregistration detection pattern, the paper interval of the transfer paper is widened to the interval required for forming the misregistration detection pattern, the paper interval of the transfer paper at the time of normal continuous printing is shortened, and the image forming efficiency is improved. It is an object of the present invention to provide a color image forming apparatus capable of improving the detection accuracy of a misregistration detection pattern and improving image quality.

According to a second aspect of the present invention, a plurality of transfer papers, which are sequentially fed from a paper supply means at a predetermined short paper interval during continuous printing, are sequentially transported on a transport belt, and are arranged along the transport belt. The image forming means forms toner images of different colors based on the image data, and sequentially transfers the toner images onto transfer paper to form a color image. When a misregistration detection pattern is formed on a conveyor belt by an image forming unit, and a misregistration correction process for detecting the misregistration detection pattern and correcting the misregistration is performed, the environment in the color image forming apparatus may be changed during continuous printing. When the temperature change exceeds a preset reference change, the interval between sheets sent out from the sheet feeding unit onto the conveyor belt is longer than the interval between sheets during normal image formation. By changing the interval to the paper interval, forming a misregistration detection pattern on each of the image forming means on the conveyor belt between the transfer sheets having the changed interval, and performing the misregistration correction processing, the environmental temperature can be reduced. Only at the time of forming the misregistration detection pattern determined based on the amount of change, the paper interval of the transfer paper is widened to the interval necessary for forming the misregistration detection pattern, and the paper interval of the transfer paper during normal continuous printing is shortened.
It is an object of the present invention to provide a color image forming apparatus capable of improving image forming efficiency and improving the detection accuracy of a misregistration detection pattern to improve image quality.

According to a third aspect of the present invention, during continuous printing, the number of continuous prints exceeds a predetermined reference number, and the amount of change in the environmental temperature in the color image forming apparatus is equal to the predetermined reference amount. If it exceeds, the paper interval sent out from the paper feeding means onto the conveyor belt is changed to a paper interval longer by a predetermined amount than the paper interval, and each image forming on the conveyor belt is performed between the transfer papers at the changed paper interval. The position shift detection pattern is formed by the means and the position shift correction processing is performed, so that the position shift detection pattern is formed only at a time when the position shift may become large, and the transfer paper is formed only when the position shift detection pattern is formed. In addition to widening the paper interval of the transfer paper to the interval necessary for forming the misregistration detection pattern, the paper interval of the transfer paper during normal continuous printing is shortened, and the image forming efficiency is further improved. , And its object is to provide a color image forming apparatus capable of improving image quality.

[0018]

According to a first aspect of the present invention, there is provided a color image forming apparatus which forms an electrostatic latent image by irradiating a rotation driven photoreceptor with writing light modulated with image data. The electrostatic latent image is formed and a predetermined color toner is supplied to the photoreceptor for development, and the toner image formed on the photoreceptor is transferred from a paper feeding unit and conveyed on a conveyance belt. Image forming means for transferring to paper to form a toner image,
A plurality of transfer papers, which are provided along the transport belt and are fed at predetermined short intervals from the paper feed unit during continuous printing, are sequentially transported on the transport belt, and each of the image forming units has a different color. Are sequentially transferred onto the transfer paper to form a color image, and a misregistration detection pattern for detecting misregistration at the time of color image formation by the plurality of image forming means is used by each of the image forming means. In the color image forming apparatus, which is formed on the transport belt, the position shift detection pattern is detected by a detection unit, and a position shift correction process of correcting the position shift based on a detection result of the detection unit is performed. At the time of printing, the number of printed sheets counting means for counting the number of continuous printed sheets, and the number of continuous printed sheets counted by the number of printed sheets counting means are set in advance. When the predetermined reference number is exceeded, the paper interval sent from the paper supply unit onto the transport belt is changed to a paper interval longer by a predetermined amount than the paper interval, and the transfer paper and the transfer at the changed paper interval are changed. The above object is attained by providing control means for performing the position shift correction processing by forming the position shift detection patterns on the transport belt between the papers by the image forming means.

According to the above configuration, during continuous printing, the transfer paper fed from the paper feeding means at a predetermined short paper interval is sequentially transported on the transport belt, and a plurality of image forming units disposed along the transport belt are provided. Means for forming toner images of different colors on the basis of the image data and sequentially transferring the toner images onto transfer paper to form a color image. When a misregistration detection pattern is formed on the conveyor belt by the means, and the misregistration correction processing for detecting the misregistration detection pattern and correcting the misregistration is performed, the number of continuous prints is set in advance during continuous printing. If the number of sheets exceeds the reference number, the interval between the sheets fed from the sheet feeding unit onto the conveyor belt is changed to the interval longer by a predetermined amount than the interval between sheets during normal image formation. The misalignment correction process is performed by forming misalignment detection patterns on each of the transfer belts between the transfer papers at different sheet intervals by the image forming means on the transport belt, so the misalignment detection determined based on the number of continuous prints is performed. The paper interval of the transfer paper can be widened to the interval required for forming the misalignment detection pattern only at the time of pattern formation, and the paper interval of the transfer paper at the time of normal continuous printing can be shortened, thereby improving the image forming efficiency. As a result, the detection accuracy of the displacement detection pattern can be improved, and the image quality can be improved.

According to a second aspect of the present invention, there is provided a color image forming apparatus which irradiates a rotationally driven photosensitive member with writing light modulated with image data to form an electrostatic latent image. A toner of a predetermined color is supplied to the formed photoreceptor and developed, and the toner image formed on the photoreceptor is transferred from a paper feeding unit to a transfer paper conveyed on a conveyance belt to transfer the toner image to the toner. A plurality of image forming means for forming an image is arranged along the transport belt, and sequentially transports the transfer paper sent out at a predetermined short paper interval from the paper feed means during continuous printing on the transport belt, Each of the image forming units sequentially transfers a toner image of a different color onto the transfer paper to form a color image, and a position shift for detecting a positional shift during the color image formation by the plurality of image forming units. detection A turn is formed on the transport belt by each of the image forming units, the position shift detection pattern is detected by a detection unit, and a position shift correction process for correcting the position shift based on a detection result of the detection unit is performed. In the color image forming apparatus, a temperature detecting unit that detects an environmental temperature in the color image forming apparatus, and during the continuous printing,
When the change amount of the environmental temperature detected by the temperature detection means exceeds a preset reference change amount, the paper interval sent from the paper supply unit onto the transport belt is changed to a paper interval longer by a predetermined amount than the paper interval. A control unit that performs the position shift correction process by forming the position shift detection pattern on the transport belt between the transfer sheet and the transfer sheet at the changed sheet interval by the image forming units; With the provision of the above, the above object is achieved.

According to the above arrangement, during continuous printing, the transfer paper fed from the paper feeding means at a predetermined short paper interval is sequentially transported on the transport belt, and a plurality of image forming units arranged along the transport belt are provided. Means for forming toner images of different colors on the basis of the image data and sequentially transferring the toner images onto transfer paper to form a color image. Means for detecting a position shift detection pattern on the conveyor belt and performing a position shift correction process of correcting the position shift by detecting the position shift detection pattern. When the change amount exceeds a preset reference change amount, the interval between sheets sent out from the sheet feeding means onto the conveyor belt is longer than the sheet interval during normal image formation by a predetermined amount. Since the misalignment correction processing is performed by forming a misalignment detection pattern on each of the image forming means on the conveyor belt between the transfer papers at the changed paper interval, the misalignment correction processing is performed. Only when forming the misregistration detection pattern determined based on the amount of change, the paper interval of the transfer paper is increased to the interval necessary for forming the misregistration detection pattern, and the paper interval of the transfer paper during normal continuous printing is shortened. As a result, the image forming efficiency can be improved, and the detection accuracy of the misregistration detection pattern can be improved, so that the image quality can be improved.

In the case of the first embodiment, for example, as set forth in claim 3, the image forming apparatus further comprises a temperature detecting means for detecting an environmental temperature in the color image forming apparatus, and At the time of printing, if the number of continuous prints counted by the number-of-prints counting means exceeds a preset reference number, and if the amount of change in the environmental temperature detected by the temperature detecting means exceeds a predetermined reference change amount, The paper interval sent out from the paper supply unit onto the transport belt is changed to a paper interval longer than the paper interval by a predetermined amount, and the transfer paper and the transfer paper having the changed paper interval are placed on the transport belt. Each of the image forming units may form the displacement detection pattern and perform the displacement correction processing.

According to the above configuration, during continuous printing, if the number of continuous prints exceeds a preset reference number and if the amount of change in the environmental temperature in the color image forming apparatus exceeds the preset reference amount. The paper interval to be sent from the paper supply unit onto the transport belt is changed to a paper interval longer than the paper interval by a predetermined amount, and each image forming unit on the transport belt between the transfer paper at the changed paper interval. Since the misregistration correction processing is performed by forming the misregistration detection pattern, the misalignment detection pattern can be formed only at a time when the misalignment may increase, and only when the misalignment detection pattern is formed. The paper interval of the transfer paper is increased to the interval required for forming the misregistration detection pattern, and the paper interval of the transfer paper during normal continuous printing can be shortened. It is possible to layer improves, thereby improving the image quality.

[0024]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. It should be noted that the embodiments described below are preferred embodiments of the present invention, and therefore, various technically preferable limitations are added. However, the scope of the present invention is not limited to the following description. The embodiments are not limited to these embodiments unless otherwise specified.

FIGS. 1 to 8 show a first embodiment of the color image forming apparatus of the present invention. FIG. 1 shows the first embodiment of the color image forming apparatus of the present invention. 1 is a schematic configuration diagram of a completed color image forming apparatus 1.

In FIG. 1, a color image forming apparatus 1 comprises:
In the main body housing, the paper feed unit 10, the transport belt mechanism 20, and the yellow (Y), magenta (M), cyan (C), and black (Bk) colors arranged along the transport belt mechanism 20. Image forming units 30Y, 30M, 30C,
30Bk, a fixing unit 40, an image position detecting unit 50, and the like. In addition to these, although not shown, a control unit for controlling each unit of the color image forming apparatus 1, a motor, and a driving source for each unit driven by the motor. And a drive mechanism for transmitting the driving force.

The paper supply unit 10 separates the recording paper (transfer paper) 12 in the paper supply cassette 11 one by one by, for example, a paper supply roller (not shown) and a separating member, and sends it to a pair of registration rollers (not shown). Roller pair is paper feed cassette 1
The timing of the recording paper 12 sent from 1 is adjusted, and the recording paper 12 is sent out to the transport belt mechanism 20 at a predetermined timing.

The transport belt mechanism 20 is provided with the transport belt 2
1, a driving roller 22 and a driven roller 23, and the like.
3 is stretched. The drive roller 22 is rotationally driven by a drive mechanism such as a motor (not shown) under the control of a system controller 71 (see FIG. 4) described later,
1 is driven to rotate counterclockwise in FIG.
The recording paper 12 sent from the paper supply unit 10 is sequentially conveyed to the image forming units 30Y, 30M, 30C, and 30Bk of each color, and the image forming units 30 of each color are conveyed to the conveyed recording paper 12.
At Y, 30M, 30C, and 30Bk, a yellow toner image, a magenta toner image, a cyan toner image, and a black toner image are sequentially formed on the recording paper 12.

Image forming section (image forming means) 30 for each color
Y, 30M, 30C, and 30Bk are as shown in FIG.
The photoconductors 31Y to 31Bk are arranged at predetermined intervals along the conveyance direction of the conveyance belt 21, and as shown in FIG.
A charging unit 32 is provided around each of the photoconductors 31Y to 31Bk.
Y to 32Bk, exposure units 33Y to 33Bk, developing unit 34Y
To 34Bk, transfer units 35Y to 35Bk, cleaning units 36Y to 36Bk, a neutralization unit (not shown), and the like. In FIG. 2, the arrow H indicates the conveyor belt 21.
Is a direction (width direction) orthogonal to the moving direction of the transfer belt 21 and indicates the main scanning direction, and an arrow T is a direction parallel to the moving direction of the transport belt 21 and indicates the sub-scanning direction.

The image forming units 30Y to 30Bk uniformly charge the photosensitive members 31Y to 31Bk, which are driven to rotate clockwise in FIG. 1 by a driving mechanism (not shown), with charging units 32Y to 32Bk. When an electrostatic latent image is formed by irradiating the photoconductors 31Y to 31Bk with laser beams modulated by image data by the 33Y to 33Bk, the developing units are applied to the photoconductors 31Y to 31Bk on which the electrostatic latent images are formed. 34Y-34
At Bk, yellow (Y), magenta (M), cyan (C), and black (Bk) toners are attached to form toner images of the respective colors. The image forming units 30Y to 30Bk are connected to the conveyor belt 21 and the photoconductor 31Y.
When the recording paper 12 is transported between the transfer portions 35Y to 35Bk, the transfer portions 35Y to 35B
k designates a transfer potential, and sequentially transfers toner images of yellow (Y), magenta (M), cyan (C), and black (Bk) on the photoconductors 31Y to 31Bk on the recording paper 12 sequentially.
And transfer it. The photoconductors 31Y to 31Bk on which the transfer of the toner image is completed are cleaned by the cleaning units 36Y to 36B.
After the residual toner is cleaned at k and the charge is removed at the charge removing unit, the charged toner is charged again by the charging units 32Y to 32Bk to perform the next image forming operation.

As described above, the recording paper 12 on which the toner images of the respective colors of yellow (Y), magenta (M), cyan (C) and black (Bk) are transferred, and the images of the respective colors are formed, is electrostatically charged. In a state of being adsorbed on the transport belt 21
The sheet is further conveyed by the conveying belt 21 and the conveying belt 2
1 and is transported to the fixing unit 40.

The fixing section 40 includes a fixing roller 41, a pressure roller 42, and a pair of discharge rollers (not shown). The fixing roller 41 and the pressing roller 42 are pressed by a predetermined pressing force, and one of them is driven to rotate, and the other is rotated. The fixing roller 41 is heated to a predetermined fixing temperature by a built-in heater. Controlled.

The fixing section 40 fixes toner images of each color of yellow (Y), magenta (M), cyan (C) and black (Bk), and fixes the recording paper 12 conveyed by the conveyance belt 21. The toner of each color is heated and pressed by the roller 41 and the pressure roller 42 so that the recording paper 12
And discharged onto a discharge tray (not shown) by a pair of discharge rollers.

The image position detecting section (detecting means) 50 is disposed downstream of the black (Bk) image forming section 30Bk in the conveying direction of the transfer paper 11, and as shown in FIG. A pair of reflective optical sensors 51 and 52 are provided in the width direction. Reflective optical sensor 51,
Although not shown, the light-emitting unit 52 includes a light-emitting unit and a light-receiving unit, and the light-emitting unit includes, for example, a light-emitting diode, and the light-receiving unit includes, for example, a photodiode.

The image forming units 30Y, 30M, 30C, and 30Bk are provided on the conveyor belt 21 by the image forming units 30Y, 30M, 30C, and 30Bk.
As shown in FIG. 5, the position detection patterns 60 are formed at both ends in the width direction of the conveyor belt 21, and the position detection patterns 60
A position detection pattern 60f parallel to the main scanning direction and a position detection pattern 60s having a specific angle, for example, an angle of 45 degrees with respect to the main scanning direction are formed.

In the image position detecting section 50, each of the reflection type optical sensors 51 and 52 emits light from the light emitting section toward the conveyor belt 21 on which the position detecting pattern 60 is formed, and the position detecting pattern 60 The light reflected by is received by the light receiving section.

The image position detecting section 50 outputs the amount of light received by the light receiving section of each of the reflection type optical sensors 51 and 52 as an analog signal to the A / D converter 76 shown in FIG.

The color image forming apparatus 1 has a circuit block configuration as shown in FIG. 4, and includes a system controller 71, a positioning controller 72, and a ROM (Read O
nlyMemory) 73, RAM (Random Access Memory) 7
4, a memory 75, an A / D converter 76, a print number counter 77, and the like.

The ROM 73 stores a system program of the color image forming apparatus 1 and executes various data necessary for executing the system program, in particular, a misregistration correction processing program incorporated in the system program. , For example, the number of registered sheets (reference number) during continuous printing. It should be noted that the number of alignment executions may be stored in the RAM 74.

The RAM 74 includes a system controller 71
Is used as a work memory or the like, and stores various data.

The system controller 71 has a ROM 73
While using the RAM 74 as a work memory on the basis of the system program therein, the respective parts of the color image forming apparatus 1 are controlled to execute a sequence as the color image forming apparatus 1 and based on the number of continuous prints during continuous printing. A displacement correction process is performed.

The A / D converter 76 converts the analog detection signals of the position detection patterns 60f and 60s input from the reflection type optical sensor 51 and the reflection type optical sensor 52 into digital signals, and outputs them to the memory 75. It is stored in the memory 75.

The print number counter (print number counting means) 77 operates under the control of the system controller 71 to count the number of prints. That is, the system controller 71 increments the count value of the print number counter 77 each time one sheet of the recording paper 12 is transported from the paper supply unit 10.

If the number-of-printed-sheets counter 77 exceeds the number of sheets to be registered during continuous printing set in advance in the ROM 73 or the RAM 74 during continuous printing, the positioning controller 72 detects the misregistration pattern stored in the memory 75. The skew deviation amount, the main scanning registration deviation amount, the main scanning magnification deviation amount, the sub-scanning registration deviation amount, and the correction amount are calculated using the signal values, and the image forming units 30Y, 30M,
A set value of a control signal such as a write clock and a write timing by each of the exposure units 33Y to 33Bk of 30C and 30Bk is output to the system controller 71.

The system controller 71 changes these write clocks, write timings, and other set values based on the set values of the write clock, write timing, and other control signals input from the alignment controller 72. , And executes a shift correction process for each color.

Therefore, the system controller 7
1 and the positioning controller 72 function as control means.

Next, the operation of the present embodiment will be described. The color image forming apparatus 1 executes a misregistration correction process for detecting misregistration of each color and correcting misregistration such as misregistration when the number of continuous printings exceeds a preset number of registration executions during continuous printing. At the same time, the conveyance interval of the recording paper 12 is set to the photoconductors 31Y to 31D only during the timing of forming the position detection patterns 60f and 60s for performing the position shift correction.
The feature is that the image quality is improved while changing the interval to be longer than one circumference of Bk to improve the production efficiency of image formation.

That is, the color image forming apparatus 1 sequentially forms an image of each color on the recording paper 12 by the image forming units 30Y, 30M, 30C, and 30Bk of each color, and forms a color image on the recording paper 12. In the continuous printing process for continuously forming images on a plurality of recording papers 12, the recording paper 12 is conveyed at a paper interval of a width PL shorter than one circumference L of the photoconductors 31Y to 31Bk, and continuous printing is performed. Is going.

However, in the above-described image formation, if the image positions of the respective colors do not match in the main scanning direction, the sub-scanning direction, the magnification and the inclination, a color shift or the like occurs, and the image quality deteriorates. Therefore, the color image forming apparatus 1 executes the positional deviation correction processing in the continuous printing if the number of continuous prints exceeds the preset number of alignment executions, but the photoconductors 31Y to 31Bk of the photoconductors 31Y to 31Bk are executed.
Even if there is eccentricity in the position detection pattern 60f,
In order to detect 60 s and correct the positional deviation, it is necessary to form the position detection patterns 60 f and 60 s to have a length L of the photoconductors 31Y to 31Bk or an integral multiple of the circumference L. In order to satisfy this demand, recording paper 1
If the paper interval of No. 2 is set to be longer than the one circumferential length L of the photoconductors 31Y to 31Bk, the paper interval becomes too wide, the image forming speed is reduced, and the productivity is reduced.

Therefore, during continuous printing, the color image forming apparatus 1 sets the paper interval of the recording paper 12 to a paper interval PL shorter than one circumference L of the photoconductors 31Y to 31Bk as shown in FIG. As shown in FIG. 6, the conveyance interval of the recording paper 12 is set to the photoconductor 31Y only during the formation timing of the position detection patterns 60f and 60s for performing the misregistration correction while improving the production efficiency of the image formation. ~ 31
The image quality is improved by changing the paper interval DL to be longer than one circumference L of Bk.

That is, the color image forming apparatus 1 is configured as shown in FIG.
As shown in (2), each time the system controller 71 conveys one sheet of the recording paper 12 from the paper supply unit 10 during the continuous printing process, the count value is incremented by the print number counter 77. The alignment controller 72 reads the count value of the print number counter 77 and stores it in the RAM 74.

In this state, during continuous printing, the positioning controller 72 reads the count value of the print number counter 77 at any time as shown in FIG. The number of continuous prints is calculated by calculating the difference between the stored count value and the calculated number of continuous prints.
It is checked whether or not the number of executed registrations during continuous printing stored in the AM 74 has exceeded (step S101). If the number of continuous printings has not exceeded the number of executed registrations, normal printing processing is performed.

In step S101, if the number of continuous prints exceeds the number of sheets to be registered, the alignment controller 7
2 indicates that the system controller 71
And the count value of the number-of-prints counter 77 at the start of printing stored in the RAM 74 is changed to the current count value of the number-of-prints counter 77. The system controller 71 receives a positioning execution request from the positioning controller 72. After the completion of writing in the next first station, the image forming unit 30Y, the paper feed timing is delayed, and the paper passing interval of the recording paper 12 is changed from the paper passing interval PL in the continuous printing shown in FIG. As shown in FIG.
It is changed to the paper passing interval DL at the time of correcting the positional deviation longer than the one circumference L of 1Y to 31Bk (step S102).

Next, the system controller 71 controls each of the image forming units 30Y, 30M, 30C, and 30Bk so that the image forming units 30Y, 30M, 30C, and 30Bk are provided at both ends in the width direction (main scanning direction) on the conveyor belt 21 as shown in FIGS. As described above, the position detection pattern 6
0f and 60s are formed (step S103), and when the formed position detection patterns 60f and 60s are conveyed to the image position detection unit 50, the reflection type optical sensors 51 and 52, which are the image position detection units 50, detect them. (Step S10
4).

That is, FIG. 8 shows each of the image forming sections 30Y and 3Y.
In order to schematically show the write start timing and the write end timing at 0M, 30C, and 30Bk, the paper passing interval of the recording paper 12 is changed from the paper passing interval PL at the time of continuous printing to the photosensitive member 31Y.
The position detection pattern 60f, 60s is changed to the paper passing interval DL at the time of correcting the positional deviation longer than the one circumference L of ~ 31Bk.
When the formation of the position detection patterns 60f and 60s is completed, the process returns from the next recording paper 12 to the paper passing interval PL during normal continuous printing, and the processing subsequent to the continuous printing processing is performed. In FIG. 8, “$ S” is the timing to start writing to the #th recording paper 12, for example, “1S”
The timing at which writing to the first sheet of recording paper 12 is started is indicated. “ΔE” indicates the timing to end writing to the #th sheet of recording paper 12, for example, “1E” indicates recording of the first sheet. The timing to end writing to the paper 12 is shown.

The detection signals from the reflection type optical sensors 51 and 52 are digitally converted by the A / D converter 76 and stored in the memory 75.

The alignment controller 72 reads out the detection results of the reflection type optical sensors 51 and 52 stored in the memory 75 and calculates the amount of displacement (step S10).
5) The amount of displacement is determined in advance in the ROM 73 or the RAM 74.
Is compared with the reference set position shift amount stored in step S1 to check whether it is within the range of the reference set position shift amount (step S1).
06).

In step S106, if the detected positional deviation is within the range of the reference set positional deviation, the positioning controller 72 notifies the system controller 71 that the positional deviation correction is unnecessary, and the system controller 71 Performs the printing process following the continuous printing.

In step S106, if the detected displacement is outside the range of the reference set displacement, the positioning controller 72 uses the displacement pattern detection signal value stored in the memory 75 to determine the skew. The amount, the main scanning registration deviation amount, the main scanning magnification deviation amount, the sub-scanning registration deviation amount, and the correction amount are calculated, and the image forming units 30Y, 30M,
A set value of a control signal such as a write clock and a write timing by each of the exposure units 33Y to 33Bk of 30C and 30Bk is output to the system controller 71.

The system controller 71, based on the set values of the control signals such as the write clock and the write timing input from the alignment controller 72, sets the image forming units 30Y, 30M, 30 as stations.
At timings other than the write timings of C and 30Bk (step S107), the set values of these write clocks, write timings, and the like are changed, and a shift correction process for each color is executed, and the process ends (step S108).

As described above, in the color image forming apparatus 1 of the present embodiment, during continuous printing, the photosensitive body 31Y
The recording paper 12 sent out at the paper interval PL shorter than the one circumference L of ~ 31Bk is sequentially conveyed on the conveyance belt 21, and
Each of the plurality of image forming units 30Y, 30M, 30C, and 30Bk arranged along the conveyor belt 21 creates a toner image of a different color based on the image data, and sequentially transfers the toner images onto the recording paper 12 to perform color printing. While forming an image, a plurality of image forming units 30Y, 30M, 30C, 30B
The position shift at the time of color image formation due to k is performed by forming the position detection patterns 60f and 60s on the conveyor belt 21 by the image forming units 30Y, 30M, 30C and 30Bk, and detecting the position detection patterns 60f and 60s. When performing the misregistration correction processing for correcting misregistration, if the number of continuous prints exceeds a preset reference number of alignment execution sheets during continuous printing, the sheet fed from the sheet feeding unit 10 onto the transport belt 21 is Interval between photoconductors 31Y to 31B
paper interval P during normal image formation shorter than one circumference L of k
L is changed to the paper interval DL which is longer by a predetermined amount than L, and each of the image forming units 30Y, 30M, 30C, 30 on the conveyor belt 21 between the recording papers 12 at the changed paper interval.
The position detection patterns 60f and 60s are formed by Bk, and the position shift correction processing is performed.

Therefore, only when forming the position detection patterns 60f and 60s determined based on the number of continuous prints, the sheet interval of the recording paper 12 is changed to the position detection patterns 60f and 60s.
Can be widened to the paper interval DL necessary for forming the image, and the paper interval PL of the recording paper 12 during normal continuous printing can be shortened.
The image forming efficiency can be improved, and the detection accuracy of the position detection patterns 60f and 60s can be improved.
Image quality can be improved.

FIGS. 9 and 10 show a second embodiment of the color image forming apparatus of the present invention. FIG. 1 shows the second embodiment of the color image forming apparatus of the present invention. FIG. 1 is a circuit block diagram of a color image forming apparatus 100 according to the present invention.

This embodiment is applied to a color image forming apparatus similar to the color image forming apparatus of the first embodiment, and in the description of the present embodiment, the first embodiment will be described. The same components as those of the color image forming apparatus 1 of the embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

In FIG. 9, the color image forming apparatus 10
Reference numeral 0 denotes the basic configuration of the hardware as shown in FIG. 1, and the same system controller 7 as the color image forming apparatus 1 of the first embodiment.
1. Positioning controller 72, ROM 73, RAM
74, a memory 75, an A / D converter 76, etc., and an environment sensor 101.

The ROM 73 stores a system program of the color image forming apparatus 1 and executes various data necessary for executing the system program, in particular, a misregistration correction processing program incorporated in the system program. , For example, the alignment execution temperature (reference temperature) during continuous printing. The alignment execution temperature may be stored in the RAM 74.

The system controller 71 has a ROM 73
While using the RAM 74 as a work memory based on the system program in the printer, the respective parts of the color image forming apparatus 1 are controlled to execute a sequence as the color image forming apparatus 1 and the position based on the environmental temperature during continuous printing. A shift correction process is performed.

An environment sensor (temperature detecting means) 101 detects an environmental temperature in the housing of the color image forming apparatus 101,
The detection result is output to the positioning controller 72 and the system controller 71.

The registration controller 72 stores the printing start environment temperature detected by the environment sensor 101 at the start of printing in the RAM 74, and calculates the difference between the environment temperature detected by the environment sensor 101 and the printing start environment temperature during continuous printing. When the temperature exceeds the alignment execution temperature during continuous printing set in advance in the ROM 73 or the RAM 74, the skew deviation amount, the main scanning registration deviation amount, The main scanning magnification deviation amount, the sub-scanning registration deviation amount, and the correction amount are calculated, and each exposure unit 33 of the image forming units 30Y, 30M, 30C, and 30Bk is calculated.
A set value of a control signal such as a write clock and a write timing according to Y to 33Bk is output to the system controller 71.

The system controller 71 changes the set values of the write clock and the write timing based on the set values of the control signals such as the write clock and the write timing input from the positioning controller 72. In addition to executing the deviation correction processing for each color, necessary control is performed based on the temperature detected by the environment sensor 101.

Next, the operation of the present embodiment will be described. The color image forming apparatus 1 performs a misregistration correction process of detecting a misregistration of each color and correcting misregistration such as misregistration by setting a temperature of a difference between an environmental temperature during continuous printing and an environmental temperature at the start of printing in advance. When the temperature exceeds the alignment execution temperature, a position detection pattern 6 for executing the correction and correcting the positional deviation is executed.
Only during the formation timing of 0f and 60s, the conveyance interval of the recording paper 12 is changed to an interval longer than one circumference of the photoconductors 31Y to 31Bk, and the production efficiency of image formation is improved.
The feature is that the image quality is improved.

That is, in the color image forming apparatus 1, at the start of printing, the alignment controller 72 reads the printing start environmental temperature detected by the environment sensor 101,
Store in AM74.

In this state, during continuous printing, the positioning controller 72 reads the current environment temperature detected by the environment sensor 101 as needed, and stores the current environment temperature and the RAM 74 as shown in FIG. The temperature of the difference from the environmental temperature at the time of printing start is calculated, and whether the calculated temperature exceeds the alignment execution temperature (reference temperature) during continuous printing stored in advance in the ROM 73 or the RAM 74, that is, the environment setting temperature It is checked whether the temperature exceeds the range (step S201). If the calculated difference temperature does not exceed the alignment execution temperature, a normal printing process is performed.

In step S201, when the calculated difference temperature exceeds the alignment execution temperature, the alignment controller 72 sends an alignment execution request to the system controller 71 and saves the environmental sensor at the start of printing stored in the RAM 74. Change the environmental temperature at the start of printing, which is the detected temperature of 101, to the current detected temperature of the environmental sensor 101,
When a positioning execution request is received from the positioning controller 72, the system controller 71 delays the sheet feeding timing after the completion of writing in the image forming unit 30Y, which is the first station, and sets the paper feeding interval of the recording paper 12 to be shorter. Is the first
As shown in FIG. 6, one circumferential length of the photoconductors 31Y to 31Bk is determined from the paper passing interval PL during continuous printing that is shorter than the circumferential length L of the photoconductors 31Y to 31Bk shown in FIG. L
It is changed to the longer sheet passing interval DL for correcting the positional deviation (step S202).

Next, the system controller 71 controls each of the image forming units 30Y, 30M, 30C, and 30Bk so that the image forming units 30Y, 30M, 30C, and 30Bk are provided at both ends in the width direction (main scanning direction) on the conveyor belt 21 as shown in FIGS. As described above, the position detection pattern 6
0f and 60s are formed (step S203), and when the formed position detection patterns 60f and 60s are conveyed to the image position detection unit 50, the reflection type optical sensors 51 and 52 which are the image position detection units 50 detect the position detection patterns 60f and 60s. (Step S20
4).

That is, FIG. 8 shows each of the image forming sections 30Y and 30Y.
As shown schematically at the writing start timing and the writing end timing at 0M, 30C, and 30Bk, the paper passing interval of the recording paper 12 is changed from the paper passing interval PL during continuous printing to the photosensitive member 31.
The position detection patterns 60 f and 60 are changed to the sheet passing interval DL at the time of correcting the positional deviation longer than one circumference L of Y to 31 Bk.
After the formation of the position detection patterns 60f and 60s is completed, the process returns from the next recording paper 12 to the paper passing interval PL during normal continuous printing, and the processing subsequent to the continuous printing processing is performed.

The detection signals of the reflection type optical sensors 51 and 52 are digitally converted by an A / D converter 76 and stored in a memory 75.
Is stored.

The positioning controller 72 reads out the detection results of the reflection type optical sensors 51 and 52 stored in the memory 75 and calculates the amount of displacement (step S20).
5) The amount of displacement is determined in advance in the ROM 73 or the RAM 74.
Is compared with the reference set position shift amount stored in step S2 to check whether it is within the range of the reference set position shift amount (step S2).
06).

In step S206, if the detected positional deviation is within the range of the reference set positional deviation, the positioning controller 72 notifies the system controller 71 that the positional deviation correction is unnecessary, and the system controller 71 Performs the printing process following the continuous printing.

In step S206, if the detected displacement is out of the range of the reference set displacement, the positioning controller 72 uses the displacement pattern detection signal value stored in the memory 75 to determine the skew. The amount, the main scanning registration deviation amount, the main scanning magnification deviation amount, the sub-scanning registration deviation amount, and the correction amount are calculated, and the image forming units 30Y, 30M,
A set value of a control signal such as a write clock and a write timing by each of the exposure units 33Y to 33Bk of 30C and 30Bk is output to the system controller 71.

The system controller 71, based on the set values of the control signals such as the write clock and the write timing input from the alignment controller 72, sets the image forming units 30Y, 30M, 30 as stations.
At timings other than the write timings of C and 30Bk (step S207), the setting values of these write clocks, write timings, and the like are changed, and a shift correction process for each color is executed, and the process ends (step S208).

As described above, the color image forming apparatus 100 of the present embodiment performs
When the amount of change in the environmental temperature within 00 exceeds an alignment execution temperature, which is a preset reference change amount, the interval between sheets sent out from the sheet supply unit 10 onto the conveyor belt 21 is changed to the photoconductors 31Y to 31Y.
One of the photoconductors 31Y to 31Bk is longer than the paper interval PL during normal image formation that is shorter than one circumference L of 31Bk by a predetermined amount.
The image forming units 30Y, 30M, 30C, and 3C are changed to the paper interval DL longer than the circumferential length L, and are placed on the conveyor belt 21 between the recording papers 12 at the changed paper interval DL.
The position detection patterns 60f and 60s are formed at 0Bk, and the position shift correction processing is performed.

Therefore, only when forming the position detection patterns 60f and 60s determined based on the change amount of the environmental temperature, the paper interval of the recording paper 12 is changed to the position detection patterns 60f and 6s.
The paper interval DL required for forming 0 s can be extended to reduce the paper interval PL of the recording paper 12 during normal continuous printing, and the image forming efficiency can be improved.
Image quality can be improved by improving the detection accuracy of the position detection patterns 60f and 60s.

FIGS. 11 and 12 show a color image forming apparatus according to a third embodiment of the present invention.
FIG. 9 is a circuit block diagram of a color image forming apparatus 100 to which a third embodiment of the color image forming apparatus of the present invention is applied.

The present embodiment is applied to a color image forming apparatus similar to the color image forming apparatus of the first embodiment, and in the description of the present embodiment, the first embodiment will be described. The same components as those of the color image forming apparatus 1 of the embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

In FIG. 11, the color image forming apparatus 2
Reference numeral 00 denotes a basic configuration of the hardware as shown in FIG. 1, and a system controller 71, a positioning controller 72, and the like which are the same as those of the color image forming apparatus 1 of the first embodiment. ROM73, RA
An M74, a memory 75, an A / D converter 76, a printed sheet counter 77 and the like are provided, and an environment sensor 101 similar to that of the second embodiment is provided.

The ROM 73 stores a system program of the color image forming apparatus 1 and executes various data necessary for executing the system program, in particular, a misregistration correction processing program incorporated in the system program. For example, the data necessary for this operation, such as the number of registration execution sheets during continuous printing (reference sheet number) and the execution temperature of registration during continuous printing (reference temperature), are stored.
It should be noted that the number of registration execution sheets and the registration execution temperature during the continuous printing may be stored in the RAM 74.

The system controller 71 has a ROM 73
While using the RAM 74 as a work memory on the basis of the system program therein, the respective parts of the color image forming apparatus 1 are controlled to execute a sequence as the color image forming apparatus 1, and the number of continuous prints during continuous printing and the environment. A misregistration correction process based on temperature is performed.

As described above, the print number counter 77
It operates under the control of the system controller 71 to count the number of prints. That is, the system controller 7
1 increments the count value of the print number counter 77 each time one sheet of recording paper 12 is conveyed from the paper supply unit 10.

The environment sensor 101 detects the environmental temperature in the housing of the color image forming apparatus 101 and outputs the detection result to the positioning controller 72 as described above.

The registration controller 72 determines that the number of prints counter 77 has exceeded the number of registration execution sheets during continuous printing set in the ROM 73 or RAM 74 in advance.
In addition, the temperature of the difference between the environmental temperature detected by the environment sensor 101 during continuous printing and the environmental temperature at the start of printing detected by the environment sensor 101 and stored in the RAM 74 is set in advance in the ROM 73 or the RAM 74 during continuous printing. When the temperature exceeds the alignment execution temperature, the skew deviation amount, the main scanning registration deviation amount, the main scanning magnification deviation amount, the sub-scanning registration deviation amount, and the correction amount are determined using the positional deviation pattern detection signal value stored in the memory 75. Calculated, and the image forming units 30Y, 30
A set value of a control signal such as a write clock and a write timing by each of the exposure units 33Y to 33Bk of M, 30C, and 30Bk is output to the system controller 71.

The system controller 71 changes the set values of the write clock and the write timing based on the set values of the control signals such as the write clock and the write timing input from the positioning controller 72. , And executes a shift correction process for each color.

Next, the operation of the present embodiment will be described. The color image forming apparatus 1 performs a misregistration correction process of detecting misregistration of each color and correcting misregistration such as misregistration, such that the number of continuous prints exceeds a preset number of registration execution sheets during continuous printing, and If the temperature of the difference between the environmental temperature and the environmental temperature at the start of printing exceeds the preset alignment execution temperature,
During the execution, the conveyance interval of the recording paper 12 is changed to an interval longer than one circumference of the photoconductors 31Y to 31Bk only during the formation timing of the position detection patterns 60f and 60s for performing the positional deviation correction. The feature is that the image quality is improved while the production efficiency of the formation is improved.

That is, in the color image forming apparatus 1, at the start of printing, the alignment controller 72 performs the continuous printing process,
Every time one sheet is conveyed from the paper supply unit 10, the count value is incremented by the print number counter 77. At the start of printing, the alignment controller 72 reads the count value of the print number counter 77 and stores it in the RAM 74. I do. Further, the positioning controller 72 reads the printing start environment temperature detected by the environment sensor 101 and stores it in the RAM 74.

In this state, during continuous printing, the positioning controller 72 reads the count value of the print number counter 77 as needed, as shown in FIG.
The number of continuous prints is calculated by obtaining the difference between the count value stored in the RAM and the current environmental temperature detected by the environmental sensor 101 as needed.
Calculate the temperature of the difference from the environmental temperature at the start of printing stored in the printer.

Then, the positioning controller 72
The calculated number of continuous prints is stored in the ROM 73 or R
It is checked whether or not the number of aligned prints during continuous printing stored in the AM 74 has exceeded (step S301). If the number of continuous prints has not exceeded the number of aligned prints, normal printing processing is performed.

In step S301, if the number of continuous prints exceeds the number of sheets for which positioning has been performed, the alignment controller 7
Step 2 checks whether the calculated difference temperature exceeds the alignment execution temperature stored in the ROM 73 or the RAM 74 in advance during continuous printing, that is, exceeds the environment setting temperature range (step S302). RA does not exceed the alignment execution temperature, RA
The number-of-printed-sheets counter 7 at the start of the printing stored in M74
7 is reset to the current count value of the number-of-prints counter 77, and normal print processing is performed (step S).
303).

In step S301, the calculated number of continuous prints exceeds the number of prints for alignment, and
If the calculated difference temperature exceeds the alignment execution temperature at 302, the alignment controller 72 issues an alignment execution request to the system controller 71 and detects the environmental sensor 101 at the start of printing stored in the RAM 74. The system controller 71 changes the printing start environment temperature, which is the temperature, to the current detection temperature of the environment sensor 101, and upon receiving a positioning execution request from the positioning controller 72, the image forming unit 30Y as the next first station. After the end of writing, the paper feed timing is delayed so that the paper passing interval of the recording paper 12 is shorter than the one circumference L of the photoconductors 31Y to 31Bk of the first embodiment shown in FIG. As shown in FIG. 6, the paper passing interval at the time of correcting the positional deviation longer than one circumference L of the photoconductors 31Y to 31Bk from the paper passing interval PL at the time. To change to L (step S30
4).

Next, the system controller 71 controls each of the image forming units 30Y, 30M, 30C, and 30Bk so that the image forming units 30Y, 30M, 30C, and 30Bk are provided at both ends in the width direction (main scanning direction) on the conveyor belt 21 as shown in FIGS. As described above, the position detection pattern 6
0f and 60s are formed (step S305), and when the formed position detection patterns 60f and 60s are conveyed to the image position detection unit 50, the reflection type optical sensors 51 and 52 as the image position detection unit 50 detect the position detection patterns 60f and 60s. (Step S30
6).

That is, FIG. 8 shows each image forming section 30Y, 3Y
As shown schematically at the writing start timing and the writing end timing at 0M, 30C, and 30Bk, the paper passing interval of the recording paper 12 is changed from the paper passing interval PL during continuous printing to the photosensitive member 31.
The position detection patterns 60 f and 60 are changed to the sheet passing interval DL at the time of correcting the positional deviation longer than one circumference L of Y to 31 Bk.
After the formation of the position detection patterns 60f and 60s is completed, the process returns from the next recording paper 12 to the paper passing interval PL during normal continuous printing, and the processing subsequent to the continuous printing processing is performed.

The detection signals of the reflection type optical sensors 51 and 52 are digitally converted by an A / D converter 76 and stored in a memory 75.
Is stored.

The positioning controller 72 reads out the detection results of the reflection type optical sensors 51 and 52 stored in the memory 75 and calculates the amount of displacement (step S30).
7) The amount of displacement is determined in advance in the ROM 73 or the RAM 74.
Is compared with the reference set position shift amount stored in step S3 to check whether it is within the range of the reference set position shift amount (step S3).
08).

In step S308, if the detected positional deviation is within the range of the reference set positional deviation, the positioning controller 72 notifies the system controller 71 that the positional deviation correction is unnecessary, and the system controller 71 Performs the printing process following the continuous printing.

If the detected positional deviation is out of the range of the reference positional deviation in step S308, the positioning controller 72 uses the positional deviation pattern detection signal value stored in the memory 75 to calculate the skew. The amount, the main scanning registration deviation amount, the main scanning magnification deviation amount, the sub-scanning registration deviation amount, and the correction amount are calculated, and the image forming units 30Y, 30M,
A set value of a control signal such as a write clock and a write timing by each of the exposure units 33Y to 33Bk of 30C and 30Bk is output to the system controller 71.

The system controller 71 sets the image forming units 30Y, 30M and 30 as the respective stations based on the set values of the control signals such as the write clock and the write timing input from the alignment controller 72.
At timings other than the write timings of C and 30Bk (step S309), the set values of these write clocks, write timings, and the like are changed, and a shift correction process for each color is executed, and the process ends (step S310).

As described above, in the color image forming apparatus 200 according to the present embodiment, during continuous printing, the number of continuous prints exceeds the number of alignment executions which is a preset reference number, and When the change amount of the environmental temperature exceeds the registration effective temperature, which is a preset reference change amount, the interval between sheets sent out from the sheet supply unit 10 onto the conveyor belt 21 is set to be longer than the circumference L of the photoconductors 31Y to 31Bk. The photosensitive member 3 is longer by a predetermined amount than the sheet interval PL during short continuous printing.
The paper interval DL is changed to a paper interval DL that is longer than one circumference L of 1Y to 31Bk, and each image forming unit 30Y, on the transport belt 21 between the recording papers 12 at the changed paper interval DL.
30M, 30C, 30Bk, the position detection pattern 60f,
The position deviation correction processing is performed by forming 60 s.

Therefore, the position detection patterns 60f and 60s can be formed only at a time when the positional deviation may increase, and the position detection patterns 6f and 60s can be formed.
Only at the time of forming 0f and 60s, the paper interval of the recording paper 12 can be increased to the paper interval DL necessary for forming the position detection patterns 60f and 60s, and the paper interval of the recording paper 12 at the time of normal continuous printing can be shortened. In addition, the image forming efficiency can be further improved, and the image quality can be improved.

Although the invention made by the inventor has been specifically described based on the preferred embodiments, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the invention. It goes without saying that it is possible.

For example, in each of the above embodiments, the reflection type sensors 51 and 52 are used as the image position detection units 50, 101 and 102, but transmission type optical sensors may be used.

[0110]

According to the color image forming apparatus of the first aspect of the present invention, during continuous printing, the transfer paper fed from the paper supply means at a predetermined short paper interval is sequentially transported on the transport belt, and the transport belt is transported. A plurality of image forming units are arranged along the line, and toner images of different colors are created based on the image data, and sequentially transferred to a transfer paper to form a color image. When performing misregistration correction processing for forming a misregistration detection pattern on each of the image forming means on the conveyor belt and detecting the misregistration detection pattern to correct the misalignment during image formation, When the number of continuous prints exceeds a preset reference number, the interval between sheets fed from the sheet feeding means onto the conveyor belt is set to a predetermined amount longer than the interval between sheets during normal image formation. Since the position deviation detection pattern is formed by each image forming means on the conveyor belt between the transfer papers at the changed paper interval and the position deviation correction processing is performed, Only when forming the misregistration detection pattern determined based on the number of prints, the paper interval of the transfer paper is increased to the interval necessary for forming the misregistration detection pattern, and the paper interval of the transfer paper during normal continuous printing is shortened. As a result, the image forming efficiency can be improved, and the detection accuracy of the misregistration detection pattern can be improved, so that the image quality can be improved.

According to the color image forming apparatus of the present invention, the transfer paper fed from the paper feeding means at a predetermined short paper interval is successively transported on the transport belt during continuous printing, and is transferred along the transport belt. A plurality of image forming means, each of which forms a toner image of a different color based on the image data and sequentially transfers the toner images onto transfer paper to form a color image; When the misalignment at the time is performed, when performing misregistration correction processing for forming a misregistration detection pattern on the transport belt by each image forming unit and detecting the misregistration detection pattern to correct the misalignment, at the time of continuous printing, If the change in the environmental temperature in the color image forming apparatus exceeds a preset reference change, the interval between sheets sent out from the sheet feeding means onto the conveyor belt is set to the value for normal image formation. The paper gap is changed to a paper gap that is longer than the paper gap by a predetermined amount, and a misregistration correction process is performed by forming a misregistration detection pattern on each of the image forming units on the conveyor belt between the transfer papers at the changed paper interval. I'm going,
Only at the time of forming the misregistration detection pattern determined based on the change in the environmental temperature, the paper interval of the transfer paper is expanded to the interval required for forming the misregistration detection pattern, and the paper interval of the transfer paper during normal continuous printing is increased. It is possible to shorten the length, improve the image forming efficiency, and improve the detection accuracy of the misregistration detection pattern, thereby improving the image quality.

According to the color image forming apparatus of the third aspect, during continuous printing, the number of continuous prints exceeds a preset reference number, and the amount of change in the environmental temperature in the color image forming apparatus is determined in advance. When the set reference change amount is exceeded,
The paper interval sent from the paper supply unit onto the transport belt is changed to a paper interval longer by a predetermined amount than the paper interval, and the position of each image forming unit on the transport belt between the transfer papers at the changed paper interval is changed. Since the misalignment detection pattern is formed and the misalignment correction processing is performed, the misalignment detection pattern can be formed only at a time when the misalignment may be large, and the transfer is performed only when the misalignment detection pattern is formed. By widening the paper interval of the paper to the interval required for forming the misregistration detection pattern, the paper interval of the transfer paper during normal continuous printing can be shortened, and the image forming efficiency can be further improved. Image quality can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic front view of a color image forming apparatus to which a first embodiment of a color image forming apparatus according to the present invention is applied.

FIG. 2 is a perspective view of a conveyance belt of the color image forming apparatus of FIG. 1 and a photoconductor of an image forming unit for each color.

FIG. 3 is a perspective view of a conveyance belt on which a position detection pattern is formed and an image position detection unit of the color image forming apparatus of FIG. 1;

FIG. 4 is a circuit block diagram of the color image forming apparatus of FIG. 1;

FIG. 5 is a plan view showing a recording paper conveyance state during normal continuous printing of the color image forming apparatus of FIG. 1;

FIG. 6 is a plan view showing a recording paper conveyance state when forming a position detection pattern in the color image forming apparatus of FIG. 1;

FIG. 7 is a flowchart illustrating a position shift correction process during continuous printing by the color image forming apparatus of FIG. 1;

FIG. 8 is a diagram showing a timing of forming the position detection pattern by the color image forming apparatus of FIG. 1 and a timing of transporting the recording paper thereafter.

FIG. 9 is a circuit block diagram of a color image forming apparatus to which a second embodiment of the color image forming apparatus of the present invention is applied.

FIG. 10 is a flowchart illustrating a positional deviation correction process during continuous printing by the color image forming apparatus of FIG. 9;

FIG. 11 is a circuit block diagram of a color image forming apparatus to which a third embodiment of the color image forming apparatus of the present invention is applied.

FIG. 12 is a flowchart illustrating a positional deviation correction process during continuous printing by the color image forming apparatus of FIG. 11;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Color image forming apparatus 10 Paper feed part 11 Paper feed cassette 12 Recording paper 20 Conveying belt mechanism part 21 Conveying belt 22 Drive roller 23 Follower roller 30Y, 30M, 30C, 30Bk Image forming part 31Y-31Bk Photoconductor 32Y-32Bk Charging part 33Y-33Bk Exposure unit 34Y-34Bk Developing unit 35Y-35Bk Transfer unit 36Y-36Bk Cleaning unit 40 Fixing unit 41 Fixing roller 42 Pressure roller 50 Image position detecting unit 51, 52 Reflective optical sensor 60, 60f, 60s Position detecting pattern 71 System Controller 72 Alignment Controller 73 ROM 74 RAM 75 Memory 76 A / D Converter 77 Printed Number Counter 100 Color Image Forming Apparatus 101 Environmental Sensor 200 Color Image Forming Apparatus

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Nobuo Iwata 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Genki Hanada 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Inside Ricoh Company (72) Inventor Hideo Nakagawa 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company (72) Toshiya Sato 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company F Terms (reference) 2H027 DA11 DA46 DE07 EB04 EC03 EC06 EC09 ED17 EE02 EE07 EF10 2H030 AA01 AB02 AD05 AD17 BB16 BB44 BB56

Claims (3)

[Claims] An electrostatic latent image is formed by irradiating a rotating photoreceptor with writing light modulated with image data, and a toner of a predetermined color is formed on the photoreceptor on which the electrostatic latent image is formed. Image forming means for supplying and developing the toner image formed on the photoreceptor to transfer the toner image formed on the photoreceptor to transfer paper conveyed on a conveying belt by being fed from a paper feeding means, thereby forming the toner image; A plurality of transfer papers, which are provided along the belt and which are fed at predetermined short paper intervals from the paper feed unit during continuous printing, are sequentially transported on the transport belt, and each of the image forming units is provided with a toner of a different color. The image is sequentially transferred onto the transfer paper to form a color image, and a positional deviation detection pattern for detecting a positional shift during the color image formation by the plurality of image forming units is transported by the image forming units. bell Formed on the color image forming apparatus that detects the position shift detection pattern by the detection unit, and performs a position shift correction process of correcting the position shift based on the detection result of the detection unit, at the time of the continuous printing, When the continuous print number counted by the print number counting means exceeds a preset reference number, the paper interval sent from the paper supply means onto the transport belt is set to Changing the paper interval to a paper interval that is longer than the paper interval by a predetermined amount, and causing the respective image forming units to form the misregistration detection pattern between the transfer paper and the transfer paper at the changed paper interval. A color image forming apparatus comprising: a control unit configured to perform the position shift correction processing. 2. An electrostatic latent image is formed by irradiating a rotationally driven photosensitive member with writing light modulated with image data, and a toner of a predetermined color is formed on the photosensitive member on which the electrostatic latent image is formed. Image forming means for supplying and developing the toner image formed on the photoreceptor to transfer the toner image formed on the photoreceptor to transfer paper conveyed on a conveying belt by being fed from a paper feeding means, thereby forming the toner image; A plurality of transfer papers, which are provided along the belt and which are fed at predetermined short paper intervals from the paper feed unit during continuous printing, are sequentially transported on the transport belt, and each of the image forming units is provided with a toner of a different color. The image is sequentially transferred onto the transfer paper to form a color image, and a positional deviation detection pattern for detecting a positional shift during the color image formation by the plurality of image forming units is transported by the image forming units. bell A color image forming apparatus formed on the color image forming apparatus and performing a position shift correction process of detecting the position shift detection pattern by a detection unit and correcting the position shift based on a detection result of the detection unit; A temperature detecting means for detecting an environmental temperature in the paper feeding means, and when the change amount of the environmental temperature detected by the temperature detecting means exceeds a preset reference change amount during the continuous printing, Is changed to a sheet interval longer than the sheet interval by a predetermined amount, and the image forming means shifts the transfer belt between the transfer sheets at the changed sheet interval on the transport belt. Control means for forming a detection pattern and performing the displacement correction processing,
A color image forming apparatus comprising: 3. The printing apparatus according to claim 1, further comprising a temperature detecting unit for detecting an environmental temperature in the color image forming apparatus, wherein the control unit sets a predetermined number of continuous prints by the print number counting unit during the continuous printing. When the change in the environmental temperature detected by the temperature detection unit exceeds a reference change amount and exceeds a predetermined reference change amount, the interval between sheets fed from the sheet feeding unit onto the transport belt is set to be smaller than the sheet interval. The position shift correction is performed by changing the sheet interval by a predetermined amount longer, and forming the position shift detection pattern on the transport belt between the transfer sheets at the changed sheet interval by the image forming units. 2. The color image forming apparatus according to claim 1, wherein the processing is performed.