JP2014035532A - Image forming device and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device or the like that properly corrects density in accordance with an image to be formed.SOLUTION: An image forming device 1 includes: an image forming part 10 that forms an image on a sheet; an image reading device 100 for reading image density; and a main control part 50 for correcting the image density. The main control part 50 includes: an image acquiring part for acquiring information on the image; a density correction deciding part that compares the density of the image to be formed on the sheet with the density read by the image reading device 100 to decide whether to correct the density of the image to be formed on the sheet by the image forming part 10; a relevance determination part that compares, when density correction of the image is decided, information on the image used in the density correction deciding part with information on the image formed on the sheet, to determine relevance between them; and correction amount deciding part that decides the correction amount of the image density on the basis of the relevance determined by the relevance determination part.

Description

  The present invention relates to an image forming apparatus and a program.

Patent Document 1 discloses an image reading unit that reads document image information, an image processing unit that performs predetermined image processing on the read document image data, and a sheet based on image data processed by the image processing unit. An image output unit that forms and outputs a toner image, and a second image reading unit that reads a print image output by the image output unit, and print image data and a document read by the second image reading unit An image forming apparatus that includes an image comparison unit that compares image data and a correction unit that corrects image processing process data by the image processing unit based on a comparison result by the image comparison unit is disclosed.
In Patent Document 2, an image is formed by an image forming unit in an image forming apparatus including a paper feeding unit that feeds paper, an image forming unit that forms an image on the fed paper, and a control unit. An image reading unit that reads an image from a sheet is provided, and the control unit compares the image read from the sheet with the image reading unit and an image to be formed on the sheet, and whether or not there is a printing failure based on a difference between the two images. When a printing failure is detected, the paper feeding unit is controlled to interrupt the paper feeding operation, and at the same time, image formation, image reading, and printing failure detection are performed on a predetermined number of fed paper. An image forming apparatus that continuously performs a sheet feeding operation by controlling a sheet feeding unit when the number or ratio of sheets of printing failure among predetermined sheets is equal to or less than a predetermined reference value. It is disclosed.
Further, Patent Document 3 discloses a second ROM for storing image data therein, a scanner unit for reading images, an image memory for storing read image data, and images stored in the second ROM and image memory. The SCU includes an SCU that processes data, and an image forming unit that includes a semiconductor laser that prints image data. The SCU causes the standard original in the second ROM to be printed by the image forming unit, and the printed standard original is a scanner unit. And the image data is stored in the second ROM as image information, and the standard image data and the stored data are compared internally to detect an image density difference at each comparison point, and an image is detected from the detected density difference. An image processing apparatus is disclosed that digitizes the density difference and estimates the state of the printing means from the digitized image density difference.

JP 2005-266690 A JP 2010-42601 A JP-A-8-190630

  Here, when the formed image is read and the image is inspected, the density at the time of image formation may be corrected based on the density of the read image. However, when the image quality of the image formed on the recording material changes before and after density correction, the user may feel unnaturalness.

  According to the first aspect of the present invention, there is provided an image forming unit that forms an image on a recording material, a density reading unit that reads the density of an image formed by the image forming unit, and a density read by the density reading unit. And a density correction unit that corrects the density of an image formed on the recording material by the image forming unit, and the density correction unit is information for forming an image on the recording material by the image forming unit. An image information acquisition unit that acquires information about an image, and a density of an image to be formed on a recording material derived from the information about the image acquired by the image information acquisition unit, and the density reading unit A density correction determination unit that compares the density and determines whether or not to correct the density of the image formed on the recording material in the image forming unit, and the density correction determination unit is determined to correct the image density The relevance determination unit that compares the information about the image used in the density correction determination unit with the information about the image formed on the previous recording material to determine the relevance, and the relationship An image forming apparatus comprising: a correction amount determining unit that determines an image density correction amount based on the relevance determined by the sex determining unit.

According to a second aspect of the present invention, the correction amount determination unit determines the correction amount so that the density of the image after correction is between the density of the image before correction and the density of the target image. The image forming apparatus according to claim 1, wherein:
According to a third aspect of the present invention, the relevance determining unit forms an image on the recording material immediately before the user who has requested that the image read by the density reading unit be formed as the relevance. 3. The image forming apparatus according to claim 1, wherein the image forming apparatus determines whether or not the user who has requested is the same.
According to a fourth aspect of the present invention, the relevance determination unit is based on the same image information as the relevance, the image read by the density reading unit and the image formed on the previous recording material. 4. The image forming apparatus according to claim 1, wherein the image forming apparatus determines whether or not the image forming apparatus is used.

  The invention according to claim 5 relates to a function of acquiring a density of an image read by a density reading unit that reads a density of the formed image in a computer, and an image that is information for forming an image on a recording material. An image formed on the recording material by comparing the function of acquiring information with the density of the image to be formed on the recording material derived from the acquired information on the image and the density read by the density reading unit A function for determining whether or not to correct the density of the image, information regarding the image of the image determined to be corrected when it is determined to correct the density of the image, and information regarding the image formed on the previous recording material Is a program that realizes a function of determining the relevance of each other and a function of determining a correction amount of the image density based on the determined relevance.

According to the first aspect of the present invention, it is possible to provide an image forming apparatus capable of performing density correction more appropriately in accordance with an image to be formed as compared with a case where the present invention is not adopted.
According to the second aspect of the present invention, compared with the case where the present invention is not adopted, even if the density of the formed image is corrected, the user is less likely to feel unnaturalness.
According to the third aspect of the present invention, when correcting the density of an image to be formed, even if the user is the same, the user is less likely to feel unnaturalness.
According to the invention of claim 4, when correcting the density of the formed image, it is difficult for the user to feel unnaturalness even when the images are the same.
According to the fifth aspect of the present invention, compared to the case where the present invention is not adopted, a function capable of more appropriately correcting the density according to the formed image can be realized by a computer.

It is a figure explaining the image forming apparatus of this Embodiment. It is a figure explaining the image reading apparatus of this Embodiment. It is a figure explaining the measurement unit. It is the block diagram which showed the function structural example of the main control part in this Embodiment. 6 is a flowchart illustrating a procedure in which a main control unit corrects the density of an image formed by an image forming unit. It is the flowchart explaining operation | movement of the relevance determination part and the correction amount determination part. It is the conceptual diagram explaining the change of the density of the image after correct | amending with the correction amount determined by the method demonstrated in FIG.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
<Description of Image Forming Apparatus>
FIG. 1 is a diagram illustrating an image forming apparatus 1 according to the present embodiment.
The image forming apparatus 1 is a so-called “tandem type” color printer. The image forming apparatus 10 forms an image on a recording material (paper) based on print data, and the operation control of the entire image forming apparatus 1 or, for example, a personal computer ( And a user interface (UI) for receiving operation inputs from a user (user) and displaying various types of information to the user. And an image reading apparatus 100 as an example of a density reading unit that reads the density of an image formed on a sheet by the image forming unit 10.

<Description of Image Forming Unit>
The image forming unit 10 is a functional unit that forms an image by, for example, electrophotography, and includes six image forming units 11C, 11M, 11HC, 11HM, 11Y as an example of toner image forming units arranged in parallel. 11K (hereinafter referred to as “image forming unit 11”), an intermediate transfer belt 20 to which each color toner image formed on the photosensitive drum 12 of each image forming unit 11 is transferred, and each image forming unit 11. And a primary transfer roll 21 that transfers (primary transfer) each color toner image to the intermediate transfer belt 20. Further, a secondary transfer roll 22 that batch-transfers (secondary transfer) each color toner image transferred onto the intermediate transfer belt 20 onto a sheet, and a fixing unit that fixes the second-transferred color toner image to the sheet. And a fixing unit 60 as an example of (fixing device). The area where the secondary transfer roll 22 is arranged and the respective color toner images on the intermediate transfer belt 20 are secondarily transferred to the paper is hereinafter referred to as “secondary transfer area Tr”.

  In addition, the image forming unit 10 cools each color toner image fixed on the sheet by the fixing unit 60 and promotes fixing of each color toner image on the sheet, a cooling unit 80 as an example of a cooling unit, And a curl correction unit 85 that corrects bending (curl). In the image forming apparatus 1 of the present embodiment, the intermediate transfer belt 20, the primary transfer roll 21, and the secondary transfer roll 22 constitute a transfer unit that transfers a toner image to a sheet.

<Description of image forming unit>
Each image forming unit 11 functions as a functional member, for example, a photosensitive drum 12 on which an electrostatic latent image is formed and then each color toner image is formed, and the surface of the photosensitive drum 12 is charged with a predetermined potential. A charger 13 that exposes the photosensitive drum 12 charged by the charger 13 based on image data, and development that develops the electrostatic latent image formed on the photosensitive drum 12 with toner of each color. And a cleaner 16 for cleaning the surface of the photosensitive drum 12 after transfer.
Each of the developing devices 15 of each image forming unit 11 is connected to toner containers 17C, 17M, 17HC, 17HM, 17Y, and 17K (hereinafter referred to as “toner containers 17”) that store toners of respective colors through toner transport paths (not shown). ing. Each color toner is supplied from the toner container 17 to the developing device 15 by a supply screw (not shown) provided in the toner conveyance path.

Each of the image forming units 11 is configured in substantially the same manner except for the toner accommodated in the developing device 15, and each of them is C (cyan) color, M (magenta) color, HC (high chroma cyan) color, and HM (high chroma magenta). Color, Y (yellow), and K (black) toner images are formed. The HC color here is a cyan color having a cyan hue, a hue that is brighter and higher in saturation than the C color, and the HM color has a magenta hue, and M color. It is a magenta color with a brighter color tone and a relatively high saturation.

<Description of Paper Conveyance System in Image Forming Apparatus>
Further, the image forming unit 10 feeds out a plurality of (two in the present embodiment) sheet storage containers 40A and 40B that store sheets and the sheets stored in the sheet storage containers 40A and 40B as a sheet transport system. Feeding rolls 41A and 41B, a first transport path R1 for transporting paper from the paper storage container 40A, and a second transport path R2 for transporting paper from the paper storage container 40B. Further, the image forming unit 10 includes a third transport path R3 that transports the paper from the paper storage container 40A and the paper storage container 40B toward the secondary transfer region Tr. In addition, the image forming unit 10 conveys the sheet on which the toner image of each color is transferred in the secondary transfer region Tr so as to pass through the fixing unit 60, the cooling unit 80, the curl correction unit 85, and the image reading apparatus 100. A fourth transport path R4 and a fifth transport path R5 for transporting the paper from the image reading apparatus 100 toward the paper stacking sections 45a and 45b provided in the discharge section of the image forming apparatus 1 are provided.
From the first conveyance path R1 to the fifth conveyance path R5, conveyance rolls and conveyance belts are arranged along the respective conveyance paths to sequentially convey the fed sheets.

<Description of double-sided conveyance system>
In addition, the image forming unit 10 serves as a double-sided conveyance system, and includes an intermediate paper storage container 42 that temporarily holds the paper on which the color toner images are fixed on the first surface by the fixing unit 60, and the paper from the image reading apparatus 100 as intermediate paper A sixth transport path R6 for transporting toward the storage container 42 and a seventh transport path R7 for transporting the paper stored in the intermediate paper storage container 42 toward the third transport path R3 are provided. Further, the image forming unit 10 is disposed on the downstream side of the image reading apparatus 100 in the sheet conveyance direction, and conveys the sheet to the fifth conveyance path R5 and the intermediate sheet storage container 42 for conveying the sheet toward the sheet stacking units 45a and 45b. A distribution mechanism unit 43 that selectively distributes paper to the six transport paths R6; a distribution mechanism unit 44 that selectively distributes paper sheets to the paper stacking unit 45a and the paper stacking unit 45b; and the paper stored in the intermediate paper storage container 42 And a feeding roll 46 that feeds toward the seventh conveyance path R7.

<Description of image forming operation>
Next, a basic image forming operation in the image forming apparatus 1 according to the present embodiment will be described with reference to FIG.
Each image forming unit 11 of the image forming unit 10 forms toner images of C, M, HC, HM, Y, and K colors by an electrophotographic process using the above functional members. Each color toner image formed by each image forming unit 11 is primary-transferred sequentially on the intermediate transfer belt 20 by the primary transfer roll 21 to form a composite toner image in which the respective color toners are superimposed. The synthetic toner image on the intermediate transfer belt 20 is conveyed to the secondary transfer region Tr in which the secondary transfer roll 22 is disposed as the intermediate transfer belt 20 moves (in the direction of the arrow).

On the other hand, in the paper transport system, the feeding rolls 41A and 41B rotate in synchronization with the image formation start timing in each image forming unit 11, and the UI unit 90, for example, out of the paper storage container 40A and the paper storage container 40B. The designated sheet is fed out by the feeding rolls 41A and 41B. The sheet fed by the feeding rolls 41A and 41B is transported along the first transport path R1 or the second transport path R2 and the third transport path R3, and reaches the secondary transfer region Tr.
In the secondary transfer region Tr, the composite toner image held on the intermediate transfer belt 20 is secondarily transferred collectively onto the paper by the transfer electric field formed by the secondary transfer roll 22.

Thereafter, the sheet on which the composite toner image is transferred is separated from the intermediate transfer belt 20 and conveyed to the fixing unit 60 along the fourth conveyance path R4. The synthesized toner image on the paper transported to the fixing unit 60 is fixed on the paper after being subjected to a fixing process by the fixing unit 60. Then, the sheet on which the fixed image is formed is cooled by the cooling unit 80, and the curl correction unit 85 corrects the bending of the sheet. Thereafter, the paper passing through the curl correction unit 85 is guided by the distribution mechanism unit 43 to the fifth transport path R5 during single-sided printing and transported toward the paper stacking units 45a and 45b.
The toner (primary transfer residual toner) adhering to the photosensitive drum 12 after the primary transfer and the toner (secondary transfer residual toner) adhering to the intermediate transfer belt 20 after the secondary transfer are respectively cleaner 16, And removed by the belt cleaner 26.

On the other hand, at the time of duplex printing, the sheet on which the fixed image is formed on the first surface of the sheet by the above-described process passes through the image reading device 100 and is then guided to the sixth transport path R6 by the distribution mechanism unit 43. The sixth transport path R6 is transported toward the intermediate paper storage container. Again, the feeding roll 46 rotates in accordance with the start timing of image formation on the second surface by each image forming unit 11, and the sheet is fed out from the intermediate sheet storage container 42. The sheet fed by the feeding rolls 41A and 41B is transported along the seventh transport path R7 and the third transport path R3, and reaches the secondary transfer region Tr.
In the secondary transfer region Tr, as in the case of the first surface, the toner images of the respective colors on the second surface held on the intermediate transfer belt 20 are collectively applied to the sheet by the transfer electric field formed by the secondary transfer roll 22. Second transfer is performed.

Then, the paper on which the toner images are transferred on both sides is fixed by the fixing unit 60 as in the case of the first side, cooled by the cooling unit 80, and further corrected by the curl correction unit 85. Then, the image recorded on the sheet is read by the image reading apparatus 100. Thereafter, the paper that has passed through the image reading apparatus 100 is guided to the fifth transport path R5 by the distribution mechanism unit 43, and is transported toward the paper stacking units 45a and 45b, and then to the paper stacking unit 45a or the paper stacking unit 45b. Discharged. As will be described in detail later, the paper stacking unit 45a is a normal paper stacking unit that discharges paper when the density of an image formed on the paper is normal. The paper stacking unit 45b is an abnormal paper stacking unit that discharges paper when the density of an image formed on the paper is out of a predetermined range. The distribution mechanism unit 44 distributes the discharge to the paper stacking unit 45a and the discharge to the paper stacking unit 45b.
In this way, the image forming process in the image forming apparatus 1 is repeatedly executed for the number of printed sheets.

<Description of Image Reading Device>
FIG. 2 is a diagram illustrating the image reading apparatus 100 according to the present embodiment.
The illustrated image reading apparatus 100 includes a light source 110 that emits light to a sheet on which an image is formed, a measurement unit 120 having various measurement surfaces for adjusting the image reading apparatus 100, a sheet and a measurement unit 120. And a CCD (Charge Coupled Device) sensor 140 that converts the light guided by the optical system 130 into light amount data.

In the present embodiment, the light source 110 includes a pair of straight tube xenon fluorescent lamps 111a and 111b. Then, light is irradiated onto the paper guided by the guide surface 101 and passing through the conveyance surface, and reflected light is generated as information of an image formed on the paper.
In the present embodiment, the light source 110 is configured by the pair of xenon fluorescent lamps 111a and 111b, so that the illuminance of the light applied to the paper is unlikely to change even when the paper is conveyed while being inclined from the conveyance surface. That is, when there is one xenon fluorescent lamp, the illuminance of light applied to the paper is likely to change when the paper is tilted. In this case, the image may not be read normally.

FIG. 3 is a diagram illustrating the measurement unit 120.
In the present embodiment, the measurement unit 120 is a dodecagonal roll having 12 faces on the side. This surface serves as various measurement surfaces for adjusting the image reading apparatus 100. The measurement unit 120 is made of aluminum, for example, and 12 surfaces are processed by cutting. From the viewpoint of suppressing measurement errors, the surface is black anodized and a measurement chart is attached to a predetermined surface with a double-sided tape or the like. The measuring unit 120 is connected to a shaft portion 121 with a stepping motor (not shown) and a reduction gear (not shown), and is rotatable about the shaft portion 121. As a result, the measurement surface necessary for adjusting the image reading apparatus 100 can be directed to the sheet conveyance surface side.

  In the present embodiment, measurement surfaces 124 and 126 are provided as measurement surfaces. The measurement surfaces 124 and 126 are provided with a plurality of reflective surfaces having different predetermined colors. In the present embodiment, the measurement surface 124 is provided with a white reference plate that performs white color calibration as a reflection surface. The measurement surface 126 is provided with a color reference plate composed of various color patches as a reflection surface for color calibration.

In the present embodiment, the measurement unit 120 is provided with a evacuation surface 122 and a sheet holding surface 123 in addition to the measurement surfaces 124 and 126.
The evacuation surface 122 is a surface for avoiding interference between the measurement unit 120 and the paper. That is, in the present embodiment, when the image reading apparatus 100 is not operated, the sheet only passes through the image reading apparatus 100. Therefore, when the image reading apparatus 100 is not operated, the measurement unit 120 is preferably retracted to a position that is not in contact with the paper. The evacuation surface 122 is a surface formed with a surface having a larger area than the other measurement surfaces, and more than the other surfaces when producing the 12 surfaces on the side of the measurement unit 120. It can be produced by cutting. Then, when the measuring unit 120 is rotated and the evacuation surface 122 faces the paper conveyance surface, the evacuation surface 122 is located below the paper conveyance surface, and the paper and the evacuation surface 122 interfere with each other. Disappear. As a result, the measurement unit 120 can be retracted to a position not in contact with the paper.

  The sheet holding surface 123 is a surface that faces the sheet conveyance surface when the image reading apparatus 100 is operated to read an image formed on the sheet. When the paper holding surface 123 faces the paper conveyance surface, the paper holding surface 123 is formed to be slightly above the paper conveyance surface. When the sheet passes through the image reading apparatus 100, the sheet can be guided so as to more closely match a predetermined conveyance surface by guiding the sheet together with the guide surface 101. Therefore, when reading an image formed on a sheet, it is possible to reduce reading variations.

  Returning to FIG. 2, the optical system 130 includes mirrors 131, 132, 133, a stop 134, and a lens 135. The light reflected on the measurement surface of the paper or the measurement unit 120 is reflected by the mirrors 131, 132, and 133, and then is reduced to a predetermined light amount by the diaphragm 134. The aperture 134 has a window portion 134a at the center, and is rotatable in the direction of the arrow about the portion of the window portion 134a. Therefore, by rotating the aperture 134, the amount of light passing through the window portion 134a can be changed, and the amount of light can be reduced to a predetermined amount. The light is collected in a line by the lens 135 and forms an image on the CCD sensor 140.

  The CCD sensor 140 is provided with a CCD 141 as an example of a light receiving unit that receives light reflected by the paper in a line. In the present embodiment, CCDs 141 corresponding to R (Red), G (Green), and B (Blue) colors are arranged in three rows, and an image recorded on a sheet can be measured with each RGB color. It has become. That is, it is a 3-line color CCD. The light received by the CCD 141 is photoelectrically converted into electric charges. This charge is transferred to the light quantity data generation unit 142.

  The light amount data generation unit 142 detects the charge transferred from the CCD 141 and generates an electric signal. This electric signal becomes light amount data (light amount value) which is information for adjusting the image forming unit 10. That is, the light amount data generation unit 142 generates light amount data for adjusting the image formed on the paper from the light received by the CCD 141. Since the CCD 141 is a color CCD of three colors R (Red), G (Green), and B (Blue), the light amount data generation unit 142 has R signal and G signal that are light amount data corresponding to each color. , B signals are generated.

<Description of method for correcting image density>
Next, a method for correcting the density of an image formed by the image forming unit 10 using the image reading apparatus 100 will be described. In the present embodiment, the main control unit 50 corrects the density of the image formed by the image forming unit 10. Therefore, in the present embodiment, the main control unit 50 functions as a density correction unit that corrects the density of the image formed on the paper by the image forming unit 10 based on the density read by the image reading device 100.

FIG. 4 is a block diagram illustrating a functional configuration example of the main control unit 50 in the present embodiment. However, FIG. 4 illustrates functions related to image density correction among various functions of the main control unit 50.
As shown in the figure, the main control unit 50 includes an image information acquisition unit 501 that acquires information about an image, which is information for forming an image on a sheet in the image forming unit 10, and an image read by the image reading apparatus 100. The read density acquisition unit 502 that acquires the density compares the density of the image to be formed on the sheet derived from the information about the image acquired by the image information acquisition unit 501 with the density read by the image reading apparatus 100. When the image forming unit 10 determines whether to correct the density of the image formed on the paper, and when the density correction determining unit 503 determines to correct the image density, the density correction determination is performed. Relevance determination in which information relating to an image used in section 503 is compared with information relating to an image formed on the previous paper to determine the relevance of each other In the image forming unit 10 based on the correction amount determined by the correction amount determination unit 505 and the correction amount determination unit 505 that determines the correction amount of the image density based on the relationship determined by the relationship determination unit 504 A density correction execution unit 506 that corrects the density of the formed image.

FIG. 5 is a flowchart illustrating a procedure in which the main control unit 50 corrects the density of an image formed by the image forming unit 10.
Hereinafter, the procedure in which the main control unit 50 corrects the density of the image formed by the image forming unit 10 will be specifically described with reference to FIGS. 4 and 5.

First, the main control unit 50 receives an instruction to print an image on a sheet by communication from a PC, operation of the UI unit 90 by a user, or the like (step 101). Then, the main control unit 50 controls the image forming unit 10 to print an image on a sheet (step 102).
Further, the sheet on which the image is printed is read by the image reading apparatus 100, and the density of the image is acquired (step 103).

Then, the image information acquisition unit 501 acquires information related to the image corresponding to the read image (step 104). Here, in the present embodiment, information relating to an image means not only image data (image information) but also information including information such as a user ID and information on the type of image data.
Next, the reading density acquisition unit 502 acquires the density read from the image reading apparatus 100 (step 105).

  Then, the density correction determination unit 503 compares the density of the image to be originally printed with the density of the image read by the image reading apparatus 100, and determines whether there is a density difference (step 106). Here, the density of the image to be originally printed can be derived from the image data acquired by the image information acquisition unit 501.

If there is no difference in density (No in step 106), the paper is discharged to the normal paper stacking portion 45a (see FIG. 1) (step 107).
If there is a density difference (Yes in step 106), the density correction determination unit 503 determines whether the density difference is equal to or greater than a predetermined threshold (step 108). If the density difference does not reach a predetermined threshold (No in Step 108), the paper is discharged to the normal paper stacking portion 45a (Step 107).

  On the other hand, if the difference in density is equal to or greater than a predetermined threshold (Yes in Step 108), the paper is discharged to the abnormal paper stacking portion 45b (Step 109). At this time, the paper is taken out from the paper storage containers 40A and 40B (see FIG. 1), and the paper in the middle of printing in any of the conveyance paths is discharged to the abnormal paper stacking portion 45b. In other words, since there is a high possibility that the density difference is also equal to or greater than a predetermined threshold value even during printing, this is also discharged to the abnormal paper stacking portion 45b.

  Then, the correction amount determination unit 505 determines the correction amount of the image density (step 110). Further, the density correction execution unit 506 corrects the density of the image formed by the image forming unit 10 based on the correction amount determined by the correction amount determination unit 505 (step 111). Then, the image printed on the paper discharged to the abnormal paper stacking section 45b is printed again using a new paper (step 112).

  However, when the density of an image is corrected, the image quality changes greatly between the image printed before correction and the image printed after correction, and the user may feel unnaturalness. This is likely to occur, for example, when the user prints a plurality of the same images and density correction is performed halfway.

Therefore, in the present embodiment, when correcting the density of the image formed by the image forming unit 10, the relevance with the image formed on the previous sheet is determined, and based on this, the density of the image is determined. Change the correction method. More specifically, the correction amount of the image density is changed based on the determined relevance.
This relevance determination is performed by the relevance determination unit 504. Then, the correction amount determination unit 505 determines an image density correction amount based on the relevance determined by the relevance determination unit 504.

Hereinafter, the operations of the relationship determination unit 504 and the correction amount determination unit 505 will be described in detail.
FIG. 6 is a flowchart illustrating the operations of the relevance determination unit 504 and the correction amount determination unit 505. The operations of the relevance determination unit 504 and the correction amount determination unit 505 shown in FIG. 6 correspond to the operation of step 110 in FIG. 5 and describe the operation performed in step 110 in more detail.

In the present embodiment, the relevancy determination unit 504 determines the relevance between an image printed on a sheet to be read by the image reading apparatus 100 and an image printed on the previous sheet.
(I) Whether the images are printed according to the request of the same user. (Ii) Whether the two images are the same image.

First, the relevancy determination unit 504 determines whether or not two images are printed according to the request of the same user from the information regarding the image acquired by the image information acquisition unit 501 (step 110-1). Whether or not the request is made by the same user can be determined from the user ID included in the information related to the image. If the request is not the same user's request (No in Step 110-1), the correction amount is determined so as to be a predetermined target value (Step 110-2).
This is because if the user is different, the image printed on the paper to be read by the image reading apparatus 100 and the image printed on the previous paper will be visually recognized by different users. This is because the user does not feel unnaturalness due to the change of.

On the other hand, if the request is from the same user (Yes in Step 110-1), it is then determined whether or not the two images are based on the same image data (Step 110-3). . If the two images are not the same image (No in step 110-3), the density is between the current density value and a predetermined target value, and the current density value is corrected to a small width. A correction amount is determined (step 110-4).
As a result, the difference in image quality between the image printed on the paper to be read by the image reading apparatus 100 and the image printed on the previous paper can be reduced, and the user can hardly be unnatural. .

If the two images are based on the same image data (Yes in step 110-3), the correction amount is determined so as to have the same density as the image formed on the previous sheet (step 110-). 5).
This is because if the printed images are the same, the user is more likely to feel unnaturalness by correcting the density of the image. Therefore, by setting the same density as the previously printed image, it is difficult to give the user unnaturalness.

FIG. 7 is a conceptual diagram illustrating a change in the density of an image after correction by the correction amount determined by the method described in FIG.
Here, the upper part of the figure shows an image to be printed on a sheet and a user who has requested printing. Here, eight images are printed on a sheet, and the contents of the printed images are sequentially “A”, “A”, “B”, “C”, “D”, “D”, “E”, It shows that it was "E". Further, the first seven images are printed at the request of the user I, and the last one image is printed at the request of the user II.
The lower part of the figure shows the density of the image that is set when eight images are printed on paper.

  At this time, in FIG. 7, regarding the density of the first image, the difference between the density of the image to be originally printed and the density of the image read by the image reading apparatus 100 does not reach the threshold value, and the correction of the density of the image is performed. (That is, No in step 108 in FIG. 5).

  On the other hand, regarding the density of the second image, the difference between the density of the image to be originally printed and the density of the image read by the image reading apparatus 100 is equal to or greater than the threshold value, and it is necessary to correct the density of the image. (That is, in the case of Yes in step 108 of FIG. 5). The image printed at this time is based on the same user request as the previous image, and the content of the image is the same “A”. Therefore, the density of the image is set to be the same density as the image formed on the previous sheet (that is, corresponding to the case of step 110-5 in FIG. 6).

  The third to fifth images are based on the same user request as the previous image. However, since the contents of the images are different, a small correction is made to gradually bring the image density closer to the target value. Performed (ie, corresponding to step 110-4 in FIG. 6).

  Further, the sixth image is based on the same user request as the previous image, and the content is “D”, so the density of the image is the same as the second image. The density is set to be the same as that of the image formed on the previous sheet.

  Further, the seventh image is based on the same user request as the previous image, but the content of the image is different, so that the image density is targeted as in the third to fifth images. A small correction is made to approach the value.

  Since the last eighth image is not based on the same user request as the previous image, the density of the image is set so that it immediately becomes the target value (ie, step 110 in FIG. 6). -2).

  As described above in detail, in the present embodiment, the information related to the image read by the image reading apparatus 100 is compared with the information related to the image formed on the previous paper to determine the relevance of each other. To do. Then, the correction amount for correcting the image density is determined. This makes it difficult for the user to feel unnaturalness due to a change in image quality when correcting the density of the image. In addition, the image quality of the image formed by the image forming apparatus 1 can be stabilized.

  In the above-described example, two examples of the relevance determined by the relevance determination unit 504 are given, but the present invention is not limited to this. For example, the correction amount may be determined based on the image data of the image read by the image reading apparatus 100 and the type of image data in which the image is formed on the previous paper. For example, if both are photographic data, the user is likely to feel a change in image quality due to density correction. Therefore, in this case, the density of the image is set to be the same density as the image formed on the previous sheet. On the other hand, when both are character data, the user hardly perceives a change in image quality due to density correction. In this case, the density of the image is set so as to perform a small correction that approaches the target value.

  In the above-described example, the image reading apparatus 100 reads the image after being fixed by the fixing unit 60, but is not limited thereto. For example, the image reading apparatus 100 may be disposed near the intermediate transfer belt 20 and the toner image transferred to the intermediate transfer belt 20 may be read as an image.

  The processing performed by the main control unit 50 described above is realized by cooperation between software and hardware resources. That is, a CPU (not shown) inside the control computer provided in the main control unit 50 executes a program that realizes each function of the main control unit 50 and realizes each of these functions.

  Therefore, the processing performed by the main control unit 50 is a function of acquiring the density of the image read by the image reading apparatus 100 that reads the density of the image formed on the paper and information for forming the image on the paper. An image formed on a sheet by comparing the function of acquiring information about an image with the density of the image to be formed on the sheet derived from the acquired information on the image and the density read by the image reading apparatus 100 The function to determine whether or not to correct the image density, and if it is determined to correct the image density, the information related to the image determined to be corrected is compared with the information related to the image formed on the previous paper As a program that realizes the function of determining the relevance of each other and the function of determining the correction amount of the image density based on the determined relevance. Rukoto can.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 10 ... Image forming part, 50 ... Main control part, 100 ... Image reading apparatus, 501 ... Image information acquisition part, 502 ... Reading density acquisition part, 503 ... Density correction determination part, 504 ... Relevance judgment , 505... Correction amount determination unit, 506... Density correction execution unit

Claims (5)

An image forming unit for forming an image on a recording material;
A density reading unit that reads the density of the image formed by the image forming unit;
A density correction unit that corrects the density of an image formed on the recording material by the image forming unit based on the density read by the density reading unit;
With
The density correction unit
An image information acquisition unit that acquires information about an image that is information for forming an image on a recording material in the image forming unit;
The density of the image to be formed on the recording material derived from the information on the image acquired by the image information acquisition unit is compared with the density read by the density reading unit, and the recording material is recorded by the image forming unit. A density correction determination unit that determines whether or not to correct the density of the formed image;
When the density correction determination unit determines to correct the image density, the information related to the image used in the density correction determination unit and the information related to the image formed on the previous recording material are compared to each other. A relevance determination unit for determining the relevance of
A correction amount determination unit that determines a correction amount of the density of the image based on the relevance determined by the relevance determination unit;
An image forming apparatus comprising:   The correction amount determination unit determines the correction amount so that the density of the image after correction is between the density of the image before correction and the density of the target image. The image forming apparatus described in 1.   In the relevance determination unit, as the relevance, a user who has requested to form an image read by the density reading unit and a user who has requested to form an image on the previous recording material are the same. 3. The image forming apparatus according to claim 1, wherein the image forming apparatus determines whether or not the image forming process is in progress.   The relevance determining unit determines, as the relevance, whether or not the image read by the density reading unit and the image formed on the previous recording material are based on the same image information. The image forming apparatus according to any one of claims 1 to 3. On the computer,
A function of acquiring the density of the image read by the density reading unit that reads the density of the formed image;
A function of acquiring information about an image, which is information for forming an image on a recording material,
Whether or not to correct the density of the image formed on the recording material by comparing the density of the image to be formed on the recording material derived from the acquired information on the image with the density read by the density reading unit The ability to determine
When it is determined to correct the density of the image, the function of comparing the information related to the image of the image determined to be corrected and the information related to the image formed on the previous recording material to determine the relevance;
A function for determining the correction amount of the image density according to the determined relevance;
A program that realizes

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