JP2022113303A - Image forming apparatus, control program, and control method - Google Patents

Abstract

To provide an image forming apparatus that can reduce the time required for correction of a toner amount control parameter and the amount of toner, and can prevent a reduction in the accuracy of image formation.SOLUTION: An image forming apparatus performs image formation by superimposing toner images formed on photoreceptors on a transfer target body with, of a plurality of image forming units each including a photoreceptor that can be brought into contact with and separated from the transfer target body, an image forming unit whose photoreceptor is in contact with the transfer target body. When changing the image forming unit used for the image formation, the image forming apparatus executes toner image density correction for the image forming units for which the image forming unit on the downstream side is changed, and does not execute the density correction for the image forming units for which the image forming unit on the downstream side is not changed.SELECTED DRAWING: Figure 8

Description

The present invention relates to an image forming apparatus, control program, and control method.

In an electrophotographic image forming apparatus, for example, an electrostatic latent image formed by exposing a charged photoreceptor is developed with toner to form a toner image on the surface of the photoreceptor, and the toner image is transferred to an intermediate transfer member. , and then transferred from the intermediate transfer member to the paper. After that, the image is formed on the paper by performing a fixing process of heating and pressurizing the toner image on the paper.

A color toner image can be formed by pressing the photoreceptors against the intermediate transfer member, and transferring the toner images formed on the respective photoreceptors so as to be overlapped on the intermediate transfer member. However, when the toner image transferred from the upstream photoreceptor to the intermediate transfer body passes through the downstream photoreceptor that is pressed against the intermediate transfer body, the toner in the toner image is affected by contact and electric force due to the pressure contact. Back transfer occurs where it adheres to the downstream photoreceptor. Reverse transfer reduces the amount of toner transferred from the upstream photoreceptor to the intermediate transfer member. Therefore, by adjusting the amount of toner developed on the upstream photoreceptor, the amount of toner transferred from the upstream photoreceptor to the intermediate transfer body is maintained regardless of the pressure contact state between the downstream photoreceptor and the intermediate transfer body. There is a need.

However, in the adjustment of the amount of toner described above, a toner patch for correction is formed in all patterns of the state of pressure contact between the downstream photoreceptor and the intermediate transfer member, the toner amount is measured, and the photoreceptor during development is measured. It is necessary to correct the above toner amount control parameter. Therefore, it takes time and the amount of toner consumed by toner patch formation increases.

The following prior arts are disclosed in the following prior art documents. A toner patch for image density adjustment is formed on the intermediate transfer belt using all five image forming units, and the toner adhesion amount of the toner patch is detected. Based on the detected toner adhesion amount, development in the five-color mode. Determine the image density conditions in the device. Any one of the specific image forming units other than the most downstream image forming unit is used to separate the image forming units downstream from the specific image forming unit from the intermediate transfer belt to apply a toner patch for correcting the image density condition. It forms and detects the amount of toner adhered. The reverse transfer rate in each image forming section is calculated from the toner adhesion amount of the toner patch for image density adjustment and the toner adhesion amount of the toner patch for image density condition correction. Then, the image density conditions in the five-color mode are corrected using the reverse transfer rate in each image forming section, and the image density conditions in other image forming modes are determined. As a result, it is possible to reduce the time required for the image density condition determination control, and to suppress the occurrence of differences in the image density and color tone of the output image between the image forming modes.

JP 2014-119724 A

However, in the prior art described above, the amount of toner adhering to the intermediate transfer belt in modes other than the five-color mode is estimated based on the reverse transfer rate, so image formation accuracy such as image density and color may be low. There is a problem of sexuality.

The present invention has been made to solve such problems. That is, it is an object of the present invention to provide an image forming apparatus, a control program, and a control method capable of reducing the time and amount of toner required for correcting the control parameter of the toner amount and suppressing deterioration in image forming accuracy.

The above problems of the present invention are solved by the following means.

(1) An image is formed on the photoreceptor by the image forming unit in which the transfer material and the photoreceptor are brought into contact with each other, among a plurality of image forming units each having a photoreceptor that can be brought into contact with and separated from the transfer material. An image forming apparatus for forming an image by superimposing the toner images formed on the transferred material, wherein when the image forming unit used for the image forming is changed, the image forming unit arranged on the downstream side is changed. The image forming apparatus having a controller that executes the density correction of the toner image for the image forming unit arranged downstream and does not execute the density correction for the image forming unit that is not changed.

(2) setting conditions regarding the density of the toner image of the image forming unit after the density correction when the density correction is executed, and the transfer target of each image forming unit arranged downstream of the image forming unit; A storage section for storing each image forming unit in association with downstream side contact/separation information indicating a state of contact/separation with the body, and the control section controls whether the image forming unit arranged on the downstream side When the downstream contact/disconnection information of the image forming unit to be changed matches the stored downstream contact/disconnection information, the setting condition associated with the matching downstream contact/disconnection information is changed to the work. The image forming apparatus according to (1) above, which is set in the image unit.

(3) When the downstream contact/separation information of the image forming unit to be changed to the image forming unit arranged on the downstream side matches the stored downstream contact/separation information, the control unit The image forming apparatus according to (2) above, wherein even if there is, if at least one of the developer and the photoreceptor included in the image forming unit arranged on the downstream side is replaced, it is determined that they do not match. .

(4) The storage section further stores the time at which the density correction is performed for each of the image forming units, and the control section controls the image forming unit for which a predetermined time or more has passed from the time at which the density correction is performed. (5) The image forming apparatus according to (2) or (3) above, wherein the stored setting conditions are not set in the (5) the storage unit stores at least one of temperature and humidity when the density correction is performed. Further storing for each of the image forming units, the control section controls the image forming in which at least one of the stored temperature and humidity has changed by a predetermined threshold or more with respect to the value stored in the storage section The image forming apparatus according to any one of (2) to (4) above, wherein the unit does not set the stored setting condition.

(6) Any one of (2) to (5) above, wherein the downstream contact/separation information indicates contact/separation states of all the image forming units arranged downstream of each image forming unit. The image forming apparatus according to 1.

(7) An image is formed on the photoreceptor by the image forming unit in which the transfer material and the photoreceptor are brought into contact with each other, among a plurality of image forming units each having a photoreceptor that can be brought into contact with and separated from the transfer material. A control program for an image forming apparatus for forming an image by superimposing the images obtained on the transferred object, the control program being arranged downstream when the image forming unit for forming the image used for the image forming is changed. the density correction is performed for the image forming unit whose image forming unit is changed, and the density correction is not performed for the image forming unit whose image forming unit is not changed and is arranged downstream. control program to let

(8) forming an image on the photoreceptor by the image forming unit in which the transfer material and the photoreceptor are brought into contact with each other, among a plurality of image forming units each having a photoreceptor that can be brought into contact with and separated from the transfer material; A control method for an image forming apparatus for forming an image by superimposing the images formed on the transferred image, the image forming unit being arranged downstream when changing the image forming unit for forming the image used for the image forming. performing density correction for the image forming unit whose image forming unit is changed, and not performing the density correction for the image forming unit whose image forming unit is not changed and is arranged downstream. .

When changing the image forming unit that forms an image, toner image density correction is executed for the image forming unit whose downstream image forming unit is changed, and for the image forming unit whose downstream image forming unit is not changed. Do not perform density correction. As a result, it is possible to reduce the amount of time and amount of toner required for correcting the toner amount control parameter, and to suppress deterioration in image forming accuracy.

1 is a schematic diagram showing the configuration of an image forming apparatus; FIG. 1 is a block diagram showing the configuration of an image forming apparatus; FIG. 3 is a configuration diagram of the main part of the image forming unit; FIG. FIG. 4 is an explanatory diagram for explaining reverse transcription; 4 is a graph showing a correspondence relationship between development DC and toner density; FIG. 10 is an explanatory view showing before and after changing the contact/separation of each photoreceptor drum with respect to the intermediate transfer belt; FIG. 10 is a diagram showing an example in which density correction is performed on any one of the image forming units; FIG. 10 is a diagram showing an example in which density correction is performed on any one of the image forming units; FIG. 10 is a diagram showing an example in which density correction is performed on any one of the image forming units; FIG. 10 is a diagram showing an example in which density correction is performed on any one of the image forming units; FIG. 10 is a diagram showing an example in which density correction is performed on any one of the image forming units; FIG. 10 is a diagram showing an example in which density correction is performed on any one of the image forming units; FIG. 10 is a diagram showing an example in which density correction is performed on any one of the image forming units; FIG. 10 is a diagram showing an example in which density correction is performed on any one of the image forming units; 4 is a flow chart showing the operation of the image forming apparatus;

An image forming apparatus according to an embodiment of the present invention will be described below with reference to the drawings. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. Also, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may differ from the actual ratios.

FIG. 1 is a schematic diagram showing the configuration of an image forming apparatus 100. As shown in FIG. FIG. 2 is a block diagram showing the configuration of the image forming apparatus 100. As shown in FIG.

Image forming apparatus 100 includes control portion 110 , storage portion 120 , communication portion 130 , operation display portion 140 , image reading portion 150 , image control portion 160 , image forming portion 170 , and toner density detection portion 180 . These components are communicatively coupled to each other by bus 190 . Image forming apparatus 100 may be configured by an MFP (MultiFunction Peripheral). Control unit 110, storage unit 120, and image control unit 160 constitute a computer.

The control unit 110 includes a CPU (Central Processing Unit) and various memories, and performs control of the above units and various arithmetic processing according to programs. Details of the action of the control unit 110 will be described later.

Storage unit 120 is configured by an SDD (Solid State Drive), HDD (Hard Disc Drive), or the like, and stores various programs and various data.

The communication unit 130 is an interface for communicating between the image forming apparatus 100 and external devices. As the communication unit 130, a network interface conforming to standards such as Ethernet (registered trademark), SATA, and IEEE1394 is used. As the communication unit 130, various local connection interfaces such as wireless communication interfaces such as Bluetooth (registered trademark) and IEEE802.11 are used.

The operation display unit 140 includes a touch panel, numeric keys, a start button, a stop button, etc., and is used to display various information and input various instructions.

The image reading unit 150 has a light source such as a fluorescent lamp and an imaging device such as a CCD (Charge Coupled Device) image sensor. The image reading unit 150 applies light from a light source to a document set at a predetermined reading position, photoelectrically converts the reflected light with an imaging device, and generates image data from the electrical signal.

The image control unit 160 performs layout processing and rasterization processing of print data included in a print job or the like received by the communication unit 130 to generate image data in bitmap format.

A print job is a general term for print commands to the image forming apparatus 100, and includes print data and print settings. The print data is data of a document to be printed, and may include various data such as image data, vector data, and text data. Specifically, the print data can be PDL (Page Description Language) data, PDF (Portable Document Format) data, or TIFF (Tagged Image File Format) data. The print settings are settings related to image formation on the paper 900, and include, for example, various settings such as the number of pages, the number of copies to be printed, the type of paper, selection of color or monochrome, and page layout.

Image forming section 170 includes image forming section 40 , fixing section 50 , paper feeding section 60 , and paper conveying section 70 .

The image forming section 40 includes image forming units 41 (41Y, 41M, 41C, 41K) corresponding to Y (yellow), M (magenta), C (cyan), and K (black) toners. Hereinafter, characters such as Y, M, C, and K are added to the image forming units 41 only when distinguishing the image forming units 41 from each other. The image forming section 40 can further include image forming units 41S1 and 41S2 corresponding to the toners of the respective colors S1 and S2, which are the special colors. In order to express the special colors S1 and S2, for example, one of the image forming units 41S1 and 41S2 is provided with clear toner for expressing glossiness and transparency, and the other is provided with clear toner for forming a white image. Equipped with white toner. The image forming unit 41 includes a developing device 411, an optical writing unit 413, a charging unit 412, a photosensitive drum 414, and a primary transfer roller 415 (see FIG. 3, etc.). Photoreceptor drum 414 constitutes a photoreceptor. Note that the developing device 411, the optical writing unit 413, the charging unit 412, and the photosensitive drum 414 can be exchangeably provided as a set. A toner image T (see FIG. 4) is formed on the photosensitive drum 414 by each image forming unit 41 through processes of charging, exposure, and development based on image data. The toner images T formed on the photoreceptor drum 414 are sequentially superimposed on the intermediate transfer belt 42 by electrostatic force due to the transfer voltage applied to the primary transfer roller 415 and are primarily transferred. As a result, the color toner image T is held on the intermediate transfer belt 42 . The color toner image T on the intermediate transfer belt 42 is secondarily transferred onto the paper 900 by the secondary transfer roller 43 . The intermediate transfer belt 42 and the paper 900 constitute a transfer receiving body.

The image forming unit 41 will be described in further detail.

FIG. 3 is a configuration diagram of a main part of the image forming unit 41. As shown in FIG. In FIG. 3, arrows indicate the rotation direction of the photosensitive drum 414 .

The charging unit 412 charges the surface of the photoreceptor drum 414 by applying a charging grid voltage to the photoreceptor drum 414 via the charging grid. The optical writing unit 413 performs exposure by forming a latent image on the photosensitive drum 414 by scanning exposure using a laser diode. The developing device 411 applies a developing DC voltage (hereinafter also referred to as “developing DC”) to the developing sleeve 411A while rotating the developing sleeve 411A, thereby causing toner to adhere to the surface of the developing sleeve 411A. As a result, the toner attached to the developing sleeve 411A is transferred to the latent image on the photosensitive drum 414, so that the latent image is developed as a toner image T. FIG. The development DC is a control parameter capable of adjusting the toner amount of the image on the paper 900, and constitutes a setting condition regarding density. Note that the potential Vi, which is the potential of the area on the photosensitive drum 414 where the latent image is formed, the development θ, which is the ratio of the rotational speeds of the developing sleeve 411A and the photosensitive drum 414, and the amount of exposure, are also setting conditions related to density. Configure. For the sake of simplicity, the following description assumes that the setting condition for density is development DC.

The photoreceptor drum 414 of each image forming unit 41 is pressed against the primary transfer roller 415 via the intermediate transfer belt 42 . As a result, the photoreceptor drum 414 is brought into contact (pressure contact) with the intermediate transfer belt 42 . For example, by moving the primary transfer roller 415 , the photoreceptor drum 414 and the primary transfer roller 415 can be brought into contact with and separated from each other (contact and separation) via the intermediate transfer belt 42 . Since the photosensitive drum 414 contacts the intermediate transfer belt 42 , the electrostatic force from the primary transfer roller 415 transfers the toner image from the photosensitive drum 414 to the intermediate transfer belt 42 .

The photoreceptor drum 414 is an image carrier having a hollow cylindrical main body (substrate) and a photosensitive layer, and is configured to rotate at a predetermined speed. The main body (substrate) is made of metal such as aluminum, for example. The photosensitive layer is made of, for example, a resin such as polycarbonate containing an organic photo conductor (OPC).

The intermediate transfer belt 42 has a volume resistivity of about 1.0×10 ⁷ to 1.0×10 ⁹ Ω·cm and a surface resistivity of about 1.0×10 ¹⁰ to 1.0×10 ¹² Ω/□. A semi-conductive endless (seamless) resin belt is used. As the resin belt, a semi-conductive belt with a thickness of 0.05 to 0.5 mm is made by dispersing a conductive material in engineering plastics such as modified polyimide, thermosetting polyimide, ethylenetetrafluoroethylene copolymer, polyvinylidene fluoride, and nylon alloy. A resin film can be used. As the intermediate transfer belt 42, a semi-conductive rubber belt having a thickness of 0.5 to 2.0 mm and having a conductive material dispersed in silicone rubber or urethane rubber can also be used. The intermediate transfer belt 42 is wound by a plurality of roller members including a tension roller 36 and supported so as to be rotatable in the vertical direction.

The primary transfer roller 415 is composed of, for example, a metal shaft and a roller-shaped conductive member using foamed rubber such as silicone or urethane covering the shaft, and faces the photosensitive drums 414 of each color with the intermediate transfer belt 42 interposed therebetween. It presses the back surface of the intermediate transfer belt 42 to form a transfer area between it and the photosensitive drum 414 . A transfer voltage having a polarity opposite to that of the toner is applied to the primary transfer roller 415 by constant voltage control, and the toner image on the photosensitive drum 414 is transferred onto the intermediate transfer belt 42 by the electrostatic force of the transfer electric field formed in the transfer area. be transcribed.

The fixing unit 50 includes a fixing roller 51a and a pressure roller 52, and the fixing roller 51a and the pressure roller 52 are pressed against each other to form a fixing nip between the fixing roller 51a and the pressure roller 52. . The fixing unit 50 heats and presses the paper 900 conveyed to the fixing nip at the fixing nip and rotates the fixing roller 51 a and the pressure roller 52 , thereby transferring the toner image on the paper 900 to the surface of the paper 900 . Melt and fix.

The paper feed unit 60 has a plurality of paper feed trays 61 and 62, and feeds the paper sheets 900 accommodated in the paper feed trays 61 and 62 one by one to the downstream transport path.

Paper conveying section 70 has a plurality of conveying rollers for conveying paper 900 , and conveys paper 900 between image forming section 40 , fixing section 50 , and paper feeding section 60 . The plurality of transport rollers include a registration roller 71 for correcting the skew of the paper 900 and a loop roller 72 for forming a predetermined amount of loop on the paper 900 .

The paper conveying unit 70 discharges the paper 900 on which the image is formed to the paper discharge tray 90 .

The toner density detection unit 180 detects the density of the toner image T on the intermediate transfer belt 42 (amount of toner adhered per unit area, hereinafter also referred to as "toner density"). The toner density detection unit 180 can be configured using, for example, an IDC sensor. The toner density detection unit 180 detects the amount of light reflected by the toner image T (for example, a toner patch when density correction described later is performed) with an IDC sensor, and converts the amount to a toner density to detect the toner density. . The toner density detection unit 180 may be configured by a known sensor such as a reflective sensor or a color detection sensor other than the IDC sensor.

The action of the control unit 110 will be described.

Based on the color of the image data, the control unit 110 brings the photosensitive drums 414 required for image formation out of the plurality of photosensitive drums 414 into contact with the intermediate transfer belt 42 . The control unit 110 primarily transfers the toner image formed on the photoreceptor drum 414 to the intermediate transfer belt 42 in the image forming unit 41 in which the photoreceptor drum 414 is brought into contact with the intermediate transfer belt 42 . The toner images are superimposed on the intermediate transfer belt 42 by . The toner images superimposed on the intermediate transfer belt 42 are secondarily transferred onto the paper 900 by the secondary transfer roller 45 .

FIG. 4 is an explanatory diagram for explaining reverse transcription. In FIG. 4, arrows indicate the rotation direction of each photosensitive drum 414 . FIG. 4A is a diagram of the photosensitive drum 414 viewed from the rotation axis direction. FIG. 4B is a diagram of the photosensitive drum 414 viewed from a direction perpendicular to the rotation axis direction.

As shown in FIG. 4, part of the toner T2 of the toner image T transferred from the photosensitive drum 4141 to the intermediate transfer belt 42 is transferred between the photosensitive drum 4142 on the downstream side of the photosensitive drum 4141 and the intermediate transfer belt 42. Due to the abutment, reverse transfer of re-adhering to the photosensitive drum 4142 occurs. Due to the reverse transfer, the toner of the toner image T transferred from the photosensitive drum 4141 to the intermediate transfer belt 42 becomes the toner T1, and the toner amount is reduced.

FIG. 5 is a graph showing the correspondence relationship between development DC and toner density. The horizontal axis of the graph indicates development DC, and the vertical axis indicates toner density. The toner density is the toner density of the C-color toner patch, and is the detection result detected by the toner density detection unit 180 . In the example of FIG. 5, the image forming apparatus 100 is assumed to have a configuration in which the photosensitive drums 414 of the YMC image forming units 41Y, 41M, and 41C simultaneously contact and separate from the intermediate transfer belt . In the following description, for the sake of simplicity, it is assumed that each photoreceptor drum 414 can come into contact with and separate from the intermediate transfer belt 42 independently, unless otherwise specified.

As shown in FIG. 5, in order to keep the toner density constant, the YMC and K photoconductor drums 414 are brought into contact with the intermediate transfer belt 42, and the YMC, K, and S1 photoconductor drums 414 are It is necessary to change the development DC depending on whether it is brought into contact with the intermediate transfer belt 42 or not. More specifically, for example, when the contact/separation state with respect to the intermediate transfer belt 42 of the photoreceptor drum 414 downstream of the C-color photoreceptor drum 414 that has transferred the C-color toner patch to the intermediate transfer belt 42 is changed. requires changing the development DC. In the example of FIG. 5, the toner density of C detected by the toner density detector 180 decreases due to reverse transfer due to contact of the photosensitive drum 414 with the intermediate transfer belt 42 in S1. Therefore, it is necessary to increase the amount of toner adhering to the C-color photosensitive drum 414 by setting the development DC when the photosensitive drum 414 of S1 is brought into contact with the intermediate transfer belt 42 to be higher than when it is separated. There is

6A and 6B are explanatory diagrams showing before and after changing the contact/separation of each photosensitive drum 414 with respect to the intermediate transfer belt 42. FIG.

In the example of FIG. 6, the S1-color photosensitive drum 414S1 is separated from the intermediate transfer belt 42 before the contact/separation change, and the S1-color photosensitive drum 414S1 is brought into contact with the intermediate transfer belt 42 after the change. ing. Further, by moving the primary transfer roller 415, the photosensitive drum 414S1 is brought into contact with and separated from the intermediate transfer belt . Note that unlike the example of FIG. 6, the photosensitive drums 414 may be brought into contact with and separated from the intermediate transfer belt 42 by moving the image forming units 41 respectively.

When changing the image forming unit 41 used for image formation (when at least one of the image forming units 41 is changed), the control unit 110 changes the image forming unit 41 arranged downstream. 41 is executed, and density correction is not executed for the image forming unit 41 arranged on the downstream side of which the image forming unit 41 is not changed. That is, the control unit 110 executes density correction only for the image forming unit 41 whose downstream image forming unit 41 is to be changed. Changing the image forming unit 41 (hereinafter also simply referred to as “change”) involves changing the contact/separation of the photosensitive drum 414 of the image forming unit 41 with respect to the intermediate transfer belt 42 (changing the image forming unit 41 used for image formation). ), and replacement of the image forming unit 41 (including replacement of a part of the image forming unit 41 (including materials and parts such as toner)). Executing the density correction for the image forming unit 41 includes executing the development DC correction for the image forming unit. Specifically, executing density correction for the image forming unit 41 includes, for example, the following. A toner patch for correction is formed on the intermediate transfer belt 42 by the image forming unit, and the toner density of the toner patch that has passed through the most downstream image forming unit 41 is detected by the toner density detection section 180 . Then, based on the detected toner density, a development DC for matching the toner density (image color) based on the image data of the toner patch for correction is calculated and set. The reason why density correction is executed for the image forming unit 41 to which the image forming unit 41 arranged on the downstream side is changed is because reverse transfer occurs in the image forming unit 41 on the downstream side. This is because the amount of toner to be reversely transferred changes due to the change.

In this way, by executing the density correction only for the image forming unit 41 whose downstream image forming unit 41 is changed, the time and toner amount required for the density correction of the image forming unit 41 can be reduced. Furthermore, by performing density correction on the image forming unit 41 whose downstream image forming unit 41 is changed, the image forming accuracy of the image forming apparatus 100 can be ensured.

The control unit 110 determines the contact/separation state between the post-correction development DC and the intermediate transfer belt 42 of each image forming unit downstream of the image forming unit 41 when density correction is performed for the image forming unit 41 . The information is stored in the storage unit 120 for each imaging unit 41 in association with the downstream contact/separation information shown. The downstream contact/separation information may be information indicating contact/separation states of all the image forming units 41 on the downstream side of each image forming unit 41 . The downstream contact/separation information may be information indicating the contact/separation state of a part of the image forming units 41 on the downstream side of each image forming unit 41 . Specifically, the downstream contact/separation information may be, for example, the contact/separate state of one image forming unit 41 adjacent to each other on the downstream side of each image forming unit 41 . In image formation based on a print job, the control unit 110 controls the downstream side contact/separation information of the image forming unit 41 whose downstream side image forming unit 41 is changed after execution of the last print job, and the stored downstream side contact/separation information. If the side contact/separation information matches, the development DC associated with the matching downstream side contact/separation information is set in the image forming unit 41 .

The control unit 110 causes the downstream contact/separation information of the image forming unit 41 whose downstream side image forming unit 41 is changed after execution of the last print job to match the stored downstream contact/separation information. Even in this case, if at least one of the developer included in the imaging unit 41 arranged downstream and the photosensitive drum 414 is replaced, it can be determined that they do not match. In this case, the control unit 110 executes density correction for the image forming unit 41 whose downstream image forming unit 41 is to be changed.

The control unit 110 further causes the storage unit 120 to store the time when the density correction was performed for each image forming unit 41 . The control unit 110 does not set the stored development DC to the image forming unit 41 for which a predetermined time or more has passed since the density correction was performed. The predetermined time can be appropriately set through experiments or the like from the viewpoint of image forming accuracy. The predetermined period of time may be eight hours, for example.

Control unit 110 can store at least one of the temperature and humidity when density correction is performed in storage unit 120 for each image forming unit using a thermo-hygrometer (not shown). The control unit 110 does not set the stored development DC to the image forming unit 41 in which at least one of the stored temperature and humidity changes from the value stored in the storage unit 120 by a predetermined threshold or more. . The predetermined threshold can be appropriately set through experiments or the like from the viewpoint of image forming accuracy.

FIGS. 7A to 7H are diagrams showing examples of the case where density correction is performed on one of the image forming units 41. FIG. In each drawing, a white circle indicates the image forming unit 41 that brings the photosensitive drum 414 into contact with the intermediate transfer belt 42 to transfer the toner image T onto the intermediate transfer belt 42 . A black circle indicates an image forming unit 41 that causes the photosensitive drum 414 to contact the intermediate transfer belt 42 to transfer the toner image T onto the intermediate transfer belt 42 and that requires density correction.

FIG. 7A is a diagram showing an example in which density correction is performed when the image forming unit 41 used for image formation is changed due to the addition of upstream colors.

In the example of FIG. 7A, by adding the S1 color as an upstream color, the change is made such that the photosensitive drum 414 of the image forming unit 41S1 is brought into contact with the intermediate transfer belt 42 after being separated from it. That is, the image forming unit 41S1 is added as an additional unit. In this case, for the S1 color image forming unit 41S1, since the development DC to be set is undetermined, density correction can be executed. On the other hand, the image forming units 41Y, 41M, 41C, and 41K for Y, M, C, and K do not need to be subjected to density correction, and the print job executed immediately before the image forming unit 41 used for image formation is changed. is used as it is. This is because the image forming units 41 on the downstream side of the Y, M, C, and K image forming units 41Y, 41M, 41C, and 41K are not changed. As for the image forming units 41Y, 41M, 41C, and 41K, the image forming unit 41S1 on the upstream side is changed, but the toner images formed by these image forming units 41Y, 41M, 41C, and 41K are the image forming units on the upstream side. Since reverse transfer does not occur in the image forming unit 41S1, the influence on the image due to the change of the image forming unit 41S1 on the upstream side can be ignored.

FIG. 7B is a diagram showing an example in which density correction is performed when the imaging unit 41 used for image formation is changed due to the addition of downstream colors.

In the example of FIG. 7B, by adding S2 as a downstream color, the change is made such that the photosensitive drum 414 of the image forming unit 41S2 is brought into contact with the intermediate transfer belt 42 from a state separated from it. That is, the image forming unit 41S2 is added as an additional unit. In this case, for the image forming unit 41S2 of S2, since the development DC to be set is undetermined, density correction can be executed. Furthermore, since the image forming units 41Y, 41M, 41C, and 41K for Y, M, C, and K are changed by adding the image forming unit 41S2 on the downstream side, density correction is performed.

FIG. 7C is a diagram showing an example in which density correction is performed when the imaging unit 41 used for image formation is changed due to the addition of upstream and downstream colors.

In the example of FIG. 7C, Y, M, and C are added as upstream colors, and S2 is added as a downstream color, so that the photosensitive drums 414 of the image forming units 41S2, 41Y, 41M, and 41C are intermediate transfer colors. A change is made in that it is brought into contact with the belt 42 from the spaced apart state. That is, a plurality of image forming units 41S2, 41Y, 41M, and 41C are added as additional units. In this case, for the image forming units 41Y, 41M, 41C, and 41S2 of Y, M, C, and S2, since the development DCs to be set have not been determined, density correction can be performed. Furthermore, since the image forming unit 41K for K is changed by adding the image forming unit 41S2 on the downstream side, density correction is executed.

FIG. 7D is a diagram showing an example in which density correction is performed when the imaging unit 41 used for image formation is changed by adding downstream colors and reducing upstream colors.

In the example of FIG. 7D, by adding S2 as a downstream color, a change is made such that the photosensitive drum 414 of the image forming unit 41S2 is brought into contact with the intermediate transfer belt 42 from a state separated from it. Further, by reducing S1 of the upstream color, a change is made such that the photosensitive drum 414 of the image forming unit 41S1 is separated from the state in which it is in contact with the intermediate transfer belt . That is, the image forming unit 41S2 is added as an increased unit, and the image forming unit 41S1 is eliminated as a decreased unit. In this case, for the image forming unit 41S2 of S2, since the development DC to be set is undetermined, density correction can be executed. Furthermore, since the image forming units 41Y, 41M, 41C, and 41K for Y, M, C, and K are changed by adding the image forming unit 41S2 on the downstream side, density correction is performed.

FIG. 7E is a diagram showing an example in which density correction is performed when the image forming unit 41 used for image formation is changed due to the reduction of downstream colors.

In the example of FIG. 7E, a change is made such that the photoreceptor drum 414 of the image forming unit 41S2 is separated from the state of being in contact with the intermediate transfer belt 42 by reducing S2 of the downstream color. That is, the image forming unit 41S2 is eliminated as a reduced unit. In this case, the image forming units 41Y, 41M, 41C, and 41K for Y, M, C, and K are changed to eliminate the image forming unit 41S2 on the downstream side, so density correction is executed.

FIG. 7F is a diagram showing an example of a case where density correction is executed when the imaging unit 41 used for image formation is changed by reducing colors other than the most upstream color and the most downstream color.

In the example of FIG. 7F, Y, M, and C other than S1, which is the most upstream color, and K, which is the most downstream color, are reduced, so that the photoreceptor drums 414 of the image forming units 41Y, 41M, and 41C are intermediate colors. A change is made in that it is separated from the state in which it is in contact with the transfer belt 42 . That is, the image forming units 41Y, 41M, and 41C are eliminated as reduced units. In this case, the image forming unit 41S1 of S1 is changed to eliminate the image forming units 41Y, 41M, and 41C on the downstream side, so density correction is executed. On the other hand, for the K image forming unit 41K, density correction is not performed because the image forming unit 41S2 on the downstream side has not been changed.

FIG. 7G is a diagram showing an example in which density correction is performed when the imaging unit 41 used for image formation is changed by adding a color between the most upstream color and the most downstream color.

In the example of FIG. 7G, Y, M, and C are added between S1, which is the most upstream color, and K, which is the most downstream color. A change is made such that the intermediate transfer belt 42 is brought into contact with the intermediate transfer belt 42 from the spaced apart state. That is, image forming units 41Y, 41M, and 41C are added as additional units. In this case, the image forming unit 41S1 of S1 is changed by adding the image forming units 41Y, 41M, and 41C on the downstream side, so density correction is executed. On the other hand, for the K image forming unit 41K, density correction is not performed because the image forming unit 41S2 on the downstream side has not been changed.

FIG. 7H is a diagram showing an example in which density correction is performed when the image forming unit 41 used for image formation is changed due to replacement of some color developers.

In the example of FIG. 7H, a change is made in which the developer (for example, toner cartridge) that is part of the C imaging unit 41C is replaced. In this case, regarding the image forming unit 41S2 of C, density correction can be executed because there is a possibility that the image forming accuracy will be lowered due to the influence of manufacturing variations of the developer due to the replacement of the developer. The image forming units 41S1, 41Y, and 41M of S1, Y, and M are also subjected to density correction because the image forming unit 41C on the downstream side is changed. For the image forming unit 41K of K, there is no need to perform density correction, and the setting value of the development DC that was set when the last print job was executed is used as it is.

Operations of the image forming apparatus 100 will be described.

FIG. 8 is a flow chart showing the operation of the image forming apparatus 100. As shown in FIG. This flowchart can be executed by the control unit 110 according to a program stored in the storage unit 120 .

The control unit 110 determines whether or not a print job has been obtained (S101). For example, the control unit 110 can determine that the print job has been acquired when the print job is received by the communication unit 130 .

The control unit 110 executes the determinations in steps S103 to S106 from the downstream color (S102). For example, if S2, K, C, M, Y, S1 in the order from the downstream color (the color of the downstream image forming unit 41) to the upstream color (the color of the upstream image forming unit 41), the above determination is made in this order. etc.

The control unit 110 determines whether or not the n colors determined in step S102 are used in the print job (S103). When the control unit 110 determines that the n colors are not used (S103: NO), the control unit 110 selects the color of the image forming unit 41 one upstream from the image forming unit 41 of the n color as the n color to be judged. Steps S103 to S106 are executed (S102).

If the controller 110 determines in step S103 that n colors will be used (S103: YES), it determines whether there is a change in the n-color image forming unit 41 (S104). When the control unit 110 determines that there is a change in the n-color image forming units 41 (S104: YES), it reserves n-color density correction (S106).

If the controller 110 determines that there is no change in the n-color image forming units 41 (S104: NO), it determines whether or not a reservation for density correction has been made for the n downstream colors (S105). If the controller 110 determines that density correction is not reserved for the n downstream colors (S105: NO), it determines the color of the image forming unit 41 one upstream from the n color image forming unit 41. Steps S103 to S106 are executed for n colors, etc. (S102).

If the controller 110 determines in step S105 that density correction has been reserved for n downstream colors (S105: YES), it reserves density correction for n colors (S106).

After executing steps S102 to S107 for all the colors of the image forming units 41 included in the image forming apparatus 100, the control unit 110 proceeds to step S108 and executes the process.

The control unit 110 determines whether or not there is a color for which a predetermined period of time has passed since the time of the last (previous) correction among the colors for which correction is reserved (S108). If the controller 110 determines that there is a color for which a predetermined time has passed since the time of the last correction (S108: YES), it executes density correction for that color (S111).

If the control unit 110 determines that there is no color for which the predetermined time has passed since the time of the last correction (S108: NO), among the colors whose correction is reserved, the humidity has reached the predetermined level since the time of the last density correction. It is determined whether or not there is a color that has changed by a threshold value or more (S109). If the control unit 110 determines that there is a color whose humidity has changed by a predetermined threshold value or more since the last density correction (S109: YES), the control unit 110 executes density correction for that color (S111).

If the control unit 110 determines that there is no color whose humidity has changed by a predetermined threshold value or more since the last correction (S109: YES), the control unit 110 selects the density correction DC from the development DCs stored in the storage unit 120. A color that is the same as the reserved color and that has matching downstream contact/separation information is extracted, and the extracted development DC is determined as the development DC after density correction (S110). If there is no developing DC stored in the storage unit 120 that has the same color as the color for which density correction is reserved and the downstream side contact/separation information matches, the density correction is not reserved. Perform density correction on the color

Embodiments of the present invention have the following effects.

When changing the image forming unit that forms an image, toner image density correction is executed for the image forming unit whose downstream image forming unit is changed, and for the image forming unit whose downstream image forming unit is not changed. Do not perform density correction. As a result, it is possible to reduce the amount of time and amount of toner required for correcting the toner amount control parameter, and to suppress deterioration in image forming accuracy.

Furthermore, when the density correction is executed, the setting condition regarding the density of the toner image of the image forming unit after the density correction and the contact/separation between the image forming unit arranged on the downstream side of the image forming unit and the transfer medium are set. It is stored for each image forming unit in association with downstream contact/separation information indicating the state. When the downstream contact information of the image forming unit whose downstream image forming unit is to be changed matches the stored downstream contact information, it is associated with the matching downstream contact/disconnection information. setting conditions are set in the image forming unit. As a result, it is possible to further reduce the amount of time and amount of toner required to correct the toner amount control parameter.

Furthermore, even if the downstream contact/separation information of the image forming unit to be changed matches the stored downstream contact/separation information, the image forming unit arranged downstream If at least one of the developer and photoreceptor included in the image forming unit is replaced, it is determined that they do not match. As a result, it is possible to suppress deterioration in image forming accuracy due to variations in developer and photoreceptor, deterioration over time, and the like.

Further, the time when the density correction is performed is stored for each image forming unit, and the stored setting conditions are not set for the image forming unit for which a predetermined time or more has passed since the time when the density correction was performed. As a result, it is possible to further suppress deterioration in image forming accuracy due to changes in toner over time and the like.

Furthermore, at least one of the temperature and humidity when density correction is performed is stored for each image forming unit, and at least one of the stored temperature and humidity changes from the stored value by a predetermined threshold or more. The stored setting conditions are not set in the image forming unit. As a result, it is possible to further suppress deterioration in image forming accuracy due to fluctuations in temperature and humidity.

Further, the downstream side contact/separation information indicates the contact/separation state of all the image forming units arranged on the downstream side for each image forming unit. As a result, it is possible to more effectively suppress deterioration in image forming accuracy.

The invention is not limited to the embodiments described above.

For example, in the embodiments, the intermediate transfer belt is used as the transfer target, but the transfer target may be a sheet of paper or the like to which the toner image is directly transferred from each photosensitive drum.

Also, part or all of the processing executed by the program in the embodiment may be executed by replacing it with hardware such as a circuit.

41 imaging unit,
411 developer,
412 charging unit,
413 optical writing unit,
414 photoreceptor drum,
415 primary transfer roller,
42 intermediate transfer belt,
100 image forming apparatus,
110 control unit,
120 storage unit,
130 Communication Department,
140 operation display unit,
150 image reading unit;
160 image control unit,
170 image forming unit;
180 toner concentration detector;

Claims (8)

A toner image formed on the photoreceptor by one of a plurality of image forming units each having a photoreceptor capable of coming into contact with and separating from a transfer material, by the image forming unit in which the transfer material and the photoreceptor are brought into contact with each other. is superimposed on the transfer material to form an image,
When changing the image forming unit used for the image formation, density correction of the toner image is executed for the image forming unit to be changed from the image forming unit arranged downstream, and the image forming unit arranged downstream is corrected. An image forming apparatus having a control section that does not execute the density correction for the image forming unit whose image forming unit is not changed. setting conditions regarding the density of the toner image of the image forming unit after the density correction when the density correction is executed, and the transfer material of each of the image forming units arranged on the downstream side of the image forming unit; further comprising a storage unit for storing each image forming unit in association with downstream contact/separation information indicating a contact/separate state;
When the downstream contact/separation information of the image forming unit to be changed from the image forming unit arranged on the downstream side matches the stored downstream contact/separation information, the control unit 2. The image forming apparatus according to claim 1, wherein said setting condition associated with downstream side contact/separation information is set in said imaging unit. Even if the downstream contact/separation information of the image forming unit to be changed to the image forming unit arranged on the downstream side matches the stored downstream contact/separation information, the control unit 3. The image forming apparatus according to claim 2, wherein when at least one of the developer and the photoreceptor included in the imaging unit arranged on the downstream side is replaced, it is determined that they do not match. the storage unit further stores a time when the density correction is performed for each image forming unit;
4. The image forming apparatus according to claim 2, wherein said control section does not set said stored setting condition to said image forming unit for which a predetermined time or more has elapsed since said density correction was performed. the storage unit further stores at least one of temperature and humidity when the density correction is performed for each image forming unit;
The control unit causes the image forming unit, in which at least one of the stored temperature and the humidity has changed by a predetermined threshold or more from the value stored in the storage unit, to set the stored setting condition 5. The image forming apparatus according to any one of claims 2 to 4, wherein . 6. The downstream side contact/separation information according to any one of claims 2 to 5, wherein the contact/separation information of each of the image forming units indicates contact/separation states of all the image forming units arranged downstream of each of the image forming units. Image forming device. An image formed on the photoreceptor by the image forming unit in which the transfer material and the photoreceptor are in contact with each other, among a plurality of image forming units each having a photoreceptor that can be brought into contact with and separated from the transfer material. A control program for an image forming apparatus for superimposing and forming an image on the transferred material,
When changing the image forming unit that forms the image used for the image formation, density correction is performed for the image forming unit to be changed in the image forming unit arranged downstream, and the image forming unit arranged downstream is changed. A control program for causing a computer to execute a procedure in which the density correction is not performed for the image forming unit whose image forming unit is not changed. An image formed on the photoreceptor by the image forming unit in which the transfer material and the photoreceptor are in contact with each other, among a plurality of image forming units each having a photoreceptor that can be brought into contact with and separated from the transfer material. A control method for an image forming apparatus for superimposing and forming an image on the transferred material, comprising:
When changing the image forming unit that forms the image used for the image formation, density correction is performed for the image forming unit to be changed in the image forming unit arranged downstream, and the image forming unit arranged downstream is changed. A control method comprising the step of not performing the density correction for the image forming unit of which the image forming unit is not changed.

Images