JP7119765B2 - Image forming apparatus, emission timing correction method, and emission timing correction program - Google Patents

Description

The present invention relates to an image forming apparatus, a light emission timing correction method, and a light emission timing correction program, and more particularly to an image forming apparatus having an exposure unit in which a plurality of light sources are arranged along the main scanning direction, and the light emission timing of the exposure unit . and a light emission timing correction program for causing a computer to execute the light emission timing correction method.

In recent years, there has been known a print head using an OLED (Organic Light-Emitting Diode) as a light source. The line head forms an electrostatic latent image on the photoreceptor drum by irradiating the photoreceptor drum as an image carrier with light emitted from a plurality of light sources. A line head is also known in which a plurality of light sources are arranged at different positions in the sub-scanning direction in order to improve the resolution.

For example, Japanese Patent Application Laid-Open No. 2008-36850 discloses an image forming apparatus that simultaneously forms images of a plurality of colors on an image carrier using a plurality of line heads corresponding to each color. A plurality of rows of light-emitting element arrays in which elements are arranged are provided in a sub-scanning direction to form a light-emitting block, a plurality of the light-emitting blocks are arranged in the main-scanning direction and the sub-scanning direction, and each of the light-emitting blocks has a negative optical magnification. a light emitter array (line head) corresponding to a single lens, means for detecting the inclination of the light emitter array with respect to the normal mounting position when the light emitter array is attached to the main body, and the detected inclination of the light emitter array means for creating skew-corrected image data according to the data; storage means for storing image data to be supplied to each of the light emitting elements; and control means for reading the image data from the storage means and transmitting the data to each of the light emitting elements. The position of the image spot formed on the image carrier by each light emitting element is reversed in the main scanning direction in each light emitting block, and the control means stores the skew corrected image data in the storage means. storing the skew-corrected image data, controlling reading so that the skew-corrected image data stored in the storage means is inverted in the sub-scanning direction within each of the light-emitting body blocks; This document describes an image forming apparatus characterized in that readout is controlled so that image spots formed by the plurality of arrayed light emitting blocks are aligned in a line in the main scanning direction of the image carrier.

However, due to mounting errors when assembling the line head and the photoreceptor drum as an image carrier, individual differences of the line head or the photoreceptor drum, etc., the relative position between the line head and the photoreceptor drum may become constant. may not be. In this case, there is a problem that the imaging spots may not line up in one line in the main scanning direction.
JP-A-2008-36850

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and one of the objects of the present invention is to provide an image forming apparatus in which deviations in the sub-scanning direction of the irradiation positions of a plurality of light sources are reduced. .

Still another object of the present invention is to provide a light emission timing correcting method that reduces deviations in the sub-scanning direction of irradiation positions of a plurality of light sources.

Still another object of the present invention is to provide a light emission timing correction program that reduces deviations in the sub-scanning direction of irradiation positions of a plurality of light sources.

In order to achieve the above object, according to one aspect of the present invention, an image forming apparatus includes an exposure unit including a plurality of light source groups in which a plurality of light sources are arranged along the main scanning direction, and a plurality of light source groups. are arranged along the sub-scanning direction intersecting the main scanning direction so that the positions of the plurality of light sources in the main scanning direction are different from each other, and move at a predetermined speed relative to the exposure unit along the sub-scanning direction. detection means for detecting an irradiation position where the image carrier is irradiated with light emitted by at least two of the plurality of light sources; correction means for correcting the light emission timing of the plurality of light sources included in each of the plurality of light source groups based on the irradiation distance in the sub-scanning direction between at least two irradiation positions detected by the detection means ; Each of the light source groups has a representative light source selected from among the plurality of light sources belonging to the light source group, and the correction means adjusts the irradiation distance in the sub-scanning direction between the plurality of irradiation positions corresponding to the representative light sources of the plurality of light source groups. , a correction amount for correcting the light emission timings of the plurality of light sources is determined for each of the plurality of light source groups .

According to this aspect, since the plurality of light sources belonging to the plurality of light source groups are arranged in the main scanning direction, the displacement of the irradiation positions in the sub-scanning direction of at least two of the plurality of light source groups can be used to determine the position of each of the plurality of light source groups. It is possible to correct the displacement of the irradiation position in the sub-scanning direction. As a result, it is possible to provide an image forming apparatus in which the displacement of the irradiation positions of the plurality of light sources in the sub-scanning direction is reduced.

In addition , since the correction amount is determined for each of the plurality of light source groups based on the irradiation distance in the sub-scanning direction between the plurality of irradiation positions corresponding to the representative light sources of the plurality of light source groups, all irradiation positions of the plurality of light sources can be There is no need for detection, the processing is simplified, and the correction amount can be easily determined.

Preferably, the plurality of light source groups includes a reference group and a reference group other than the reference group, and the correcting means detects the reference group position detected as the irradiation position by the detection means with respect to the representative light source belonging to the reference group and the reference group. A correction amount for correcting the light emission timing of the plurality of light sources belonging to the reference group based on the irradiation distance in the sub-scanning direction between the representative light source belonging to the reference group position and the reference group position detected as the irradiation position by the detection means. to decide.

According to this aspect, the amount of correction for correcting the light emission timings of the plurality of light sources belonging to the reference group is based on the irradiation distance in the sub-scanning direction between the reference group position with respect to the reference group and the reference group position with respect to the reference group. is determined, the irradiation positions of the plurality of light sources belonging to the reference group can be aligned with the irradiation positions of the plurality of light sources belonging to the reference group.

According to another aspect of the present invention, an image forming apparatus includes an exposure unit including a plurality of light source groups in which a plurality of light sources are arranged along a main scanning direction; A plurality of light sources are arranged along the sub-scanning direction intersecting the main scanning direction so that the positions of the directions are different from each other, and move at a predetermined speed relative to the exposure unit along the sub-scanning direction. and at least two light sources belonging to at least two of the plurality of light source groups out of the plurality of light sources are detected by the detection device. correction means for correcting light emission timings of the plurality of light sources included in each of the plurality of light source groups based on the irradiation distance in the sub-scanning direction between the two irradiation positions; having a representative light source selected from among the plurality of light sources belonging thereto, the plurality of light source groups including at least two representative groups, the at least two representative groups including a reference group and a reference group other than the reference group; , the correction means calculates, for each of the plurality of light source groups, the arrangement distance between the light source group and the reference group, the arrangement distance between the reference group and the reference group, and the representative light source belonging to the reference group by the detection means Light emission of the plurality of light sources formed in the light source group based on the representative distance in the sub-scanning direction between the detected irradiation position and the irradiation position detected by the detecting means with respect to the representative light source belonging to the reference group. A correction amount for correcting the timing is determined.

According to this aspect, for each of the plurality of light source groups, the arrangement distance between the light source group and the reference group, the arrangement distance between the reference group and the reference group, the irradiation position with respect to the reference group, and the irradiation position with respect to the reference group and the representative distance in the sub-scanning direction between and the correction amounts of the plurality of light sources formed in the light source group. Therefore, since it is sufficient to detect the irradiation position of each of at least two representative groups, there is no need to detect the irradiation position corresponding to each of the plurality of light source groups, which simplifies the processing and allows easy determination of the correction amount. can do.

Preferably, the reference group is a light source group in which a line connecting a representative light source belonging to the reference group and the center of rotation of the image carrier intersects the surface of the image carrier at a perpendicular angle or a most perpendicular angle, among the plurality of light source groups. .

According to this aspect, since the angle at which the line connecting the plurality of light sources belonging to the reference group and the center of rotation of the image carrier intersects the surface of the image carrier at a perpendicular or most perpendicular angle, the reference for the deformation of the image carrier is It is possible to reduce the deviation of the irradiation position of the group.

According to another aspect of the present invention, an image forming apparatus includes an exposure unit including a plurality of light source groups in which a plurality of light sources are arranged along a main scanning direction; A plurality of light sources are arranged along the sub-scanning direction intersecting the main scanning direction so that the positions of the directions are different from each other, and move at a predetermined speed relative to the exposure unit along the sub-scanning direction. and at least two light sources belonging to at least two of the plurality of light source groups out of the plurality of light sources are detected by the detection device. correction means for correcting light emission timings of the plurality of light sources included in each of the plurality of light source groups based on the irradiation distance in the sub-scanning direction between the two irradiation positions; A plurality of substrates on which a plurality of light sources belonging to each are formed, at least one light source group included in each of the plurality of substrates includes a substrate representative group, and each of the plurality of light source groups includes a plurality of light sources belonging to the light source group. and the correction means corrects the substrate in the sub-scanning direction between the plurality of irradiation positions respectively detected by the detection means for the plurality of representative light sources belonging to the plurality of substrate representative groups. Based on the distance, a first correction amount for correcting the light emission timings of the plurality of light sources formed on the substrate is determined for each of the plurality of substrates.

According to this aspect, the first correction amount is determined for each of the plurality of substrates based on the substrate distance in the sub-scanning direction between the plurality of irradiation positions for each of the plurality of substrate representative groups. Therefore, since it is sufficient to detect the irradiation position for each of the plurality of substrate representative groups, there is no need to detect the irradiation position corresponding to each of the plurality of light source groups, which simplifies the processing and easily determines the correction amount. be able to.

Preferably, the plurality of light source groups included in each of the plurality of substrates includes a reference group and a reference group other than the reference group, and the correction means selects a representative light source belonging to the reference group included in the substrate for each of the plurality of substrates. irradiation in the sub-scanning direction between the reference group position detected as the irradiation position by the detection means and the reference group position detected as the irradiation position by the detection means for the representative light source belonging to the reference group included in the substrate A second correction amount for correcting the light emission timings of the plurality of light sources belonging to the reference group is determined based on the distance.

According to this aspect, for each of the plurality of substrates, the plurality of light sources belonging to the reference group is determined based on the irradiation distance in the sub-scanning direction between the reference group position with respect to the reference group included in the substrate and the reference group position with respect to the reference group. A second correction amount for correcting the light emission timing of is determined. Therefore, since the second correction amount for each of the plurality of light source groups is determined for each of the plurality of substrates, the correction amount can be determined accurately.

Preferably, the apparatus further comprises exposure control means for controlling the exposure unit to emit light from the plurality of light sources, and the detection means irradiates the image carrier with the light emitted from the plurality of light sources at the same position in the sub-scanning direction. The irradiation position is detected in a state in which the exposure control means causes the plurality of light sources to emit light at the light emission timing.

According to this aspect, the plurality of light sources emit light so that the light emitted from the plurality of light sources irradiates the image carrier at the same position in the sub-scanning direction. It suffices to detect whether or not they are arranged in a direction, and correction can be easily made.

According to still another aspect of the present invention, a light emission timing correcting method is performed by an image forming apparatus having an exposure unit including a plurality of light source groups in which a plurality of light sources are arranged along a main scanning direction. In the correction method, the plurality of light source groups are arranged along a sub-scanning direction intersecting the main scanning direction so that the positions of the plurality of light sources in the main scanning direction are different from each other, and the sub-scanning direction is arranged relative to the exposure unit. a detection step of detecting an irradiation position where an image carrier moving at a predetermined speed in a scanning direction is irradiated with light emitted from at least two of a plurality of light sources; correction for correcting the light emission timings of the plurality of light sources included in each of the plurality of light source groups based on the distance in the sub-scanning direction between at least two irradiation positions detected in the detection step for at least two light sources belonging to each of the each of the plurality of light source groups has a representative light source selected from among the plurality of light sources belonging to the light source group; A step of determining, for each of the plurality of light source groups, a correction amount for correcting the light emission timing of the plurality of light sources based on the irradiation distance in the sub-scanning direction between positions .

According to this aspect, it is possible to provide a light emission timing correcting method that reduces deviations in the sub-scanning direction of the irradiation positions of the plurality of light sources.

According to still another aspect of the present invention, a light emission timing correcting method is performed by an image forming apparatus having an exposure unit including a plurality of light source groups in which a plurality of light sources are arranged along a main scanning direction. In the correction method, the plurality of light source groups are arranged along a sub-scanning direction intersecting the main scanning direction so that the positions of the plurality of light sources in the main scanning direction are different from each other, and the sub-scanning direction is arranged relative to the exposure unit. a detection step of detecting an irradiation position where an image carrier moving at a predetermined speed in a scanning direction is irradiated with light emitted from at least two of a plurality of light sources; correction for correcting the light emission timings of the plurality of light sources included in each of the plurality of light source groups based on the distance in the sub-scanning direction between at least two irradiation positions detected in the detection step for at least two light sources belonging to each of the each of the plurality of light source groups has a representative light source selected from among the plurality of light sources belonging to the light source group; the plurality of light source groups includes at least two representative groups; The group includes a reference group and reference groups other than the reference group, and the correction step includes, for each of the plurality of light source groups, an arrangement distance between the light source group and the reference group and a distance between the reference group and the reference group. an arrangement distance and a representative distance in the sub-scanning direction between the irradiation position detected in the detection step for the representative light source belonging to the reference group and the irradiation position detected in the detection step for the representative light source belonging to the reference group; , determining a correction amount for correcting the light emission timing of the plurality of light sources formed in the light source group.

According to still another aspect of the present invention, a light emission timing correcting method is performed by an image forming apparatus having an exposure unit including a plurality of light source groups in which a plurality of light sources are arranged along a main scanning direction. In the correction method, the plurality of light source groups are arranged along a sub-scanning direction intersecting the main scanning direction so that the positions of the plurality of light sources in the main scanning direction are different from each other, and the sub-scanning direction is arranged relative to the exposure unit. a detection step of detecting an irradiation position where an image carrier moving at a predetermined speed in a scanning direction is irradiated with light emitted from at least two of a plurality of light sources; correction for correcting the light emission timings of the plurality of light sources included in each of the plurality of light source groups based on the distance in the sub-scanning direction between at least two irradiation positions detected in the detection step for at least two light sources belonging to each of the each of the plurality of light source groups has a representative light source selected from among the plurality of light sources belonging to the light source group; the plurality of light source groups includes at least two representative groups; and the exposure unit comprises: including a plurality of substrates formed with a plurality of light sources belonging to at least one of the plurality of light source groups, wherein at least one light source group included in each of the plurality of substrates includes a substrate representative group; and each of the plurality of light source groups , a representative light source selected from among the plurality of light sources belonging to the light source groups, and the correcting step includes adjusting between the plurality of irradiation positions respectively detected in the detecting step for the plurality of representative light sources belonging to the plurality of substrate representative groups. determining, for each of the substrates, a first correction amount for correcting the light emission timings of the plurality of light sources formed on the substrate, based on the substrate distance in the sub-scanning direction.

According to still another aspect of the present invention, the emission timing correction program is executed by a computer that controls an image forming apparatus having an exposure unit that includes a plurality of light source groups in which a plurality of light sources are arranged along the main scanning direction. wherein the light source groups are arranged along a sub-scanning direction intersecting the main scanning direction so that the positions of the light sources in the main scanning direction are different from each other, and a detection step of detecting an irradiation position where light emitted by at least two of a plurality of light sources is irradiated onto an image carrier moving at a predetermined speed relative to an exposure unit along a path; Light emission of a plurality of light sources included in each of a plurality of light source groups based on a distance in the sub-scanning direction between at least two irradiation positions detected in the detection step for at least two light sources belonging to at least two of the groups. a correction step of correcting the timing, wherein each of the plurality of light source groups has a representative light source selected from among the plurality of light sources belonging to the light source group; 3. determining, for each of the plurality of light source groups, a correction amount for correcting the light emission timing of the plurality of light sources based on the irradiation distance in the sub-scanning direction between the plurality of irradiation positions corresponding to the representative light source; Including .

According to this aspect, it is possible to provide a light emission timing correction program that reduces the displacement of the irradiation positions of the plurality of light sources in the sub-scanning direction.

According to still another aspect of the present invention, the emission timing correction program is executed by a computer that controls an image forming apparatus having an exposure unit that includes a plurality of light source groups in which a plurality of light sources are arranged along the main scanning direction. wherein the light source groups are arranged along a sub-scanning direction intersecting the main scanning direction so that the positions of the light sources in the main scanning direction are different from each other, and a detection step of detecting an irradiation position where light emitted by at least two of a plurality of light sources is irradiated onto an image carrier moving at a predetermined speed relative to an exposure unit along a path; Light emission of a plurality of light sources included in each of a plurality of light source groups based on a distance in the sub-scanning direction between at least two irradiation positions detected in the detection step for at least two light sources belonging to at least two of the groups. and a correction step of correcting the timing, wherein each of the plurality of light source groups has a representative light source selected from among the plurality of light sources belonging to the light source group, and the plurality of light source groups has at least two representative light sources. and the at least two representative groups include a reference group and a reference group other than the reference group, and the correcting step includes, for each of the plurality of light source groups, a placement distance between the light source group and the reference group The arrangement distance between the group and the reference group, and the distance between the irradiation position detected in the detection step for the representative light source belonging to the reference group and the irradiation position detected in the detection step for the representative light source belonging to the reference group and a representative distance in the sub-scanning direction of the light source group.

According to still another aspect of the present invention, the emission timing correction program is executed by a computer that controls an image forming apparatus having an exposure unit that includes a plurality of light source groups in which a plurality of light sources are arranged along the main scanning direction. wherein the light source groups are arranged along a sub-scanning direction intersecting the main scanning direction so that the positions of the light sources in the main scanning direction are different from each other, and a detection step of detecting an irradiation position where light emitted by at least two of a plurality of light sources is irradiated onto an image carrier moving at a predetermined speed relative to an exposure unit along a path; Light emission of a plurality of light sources included in each of a plurality of light source groups based on a distance in the sub-scanning direction between at least two irradiation positions detected in the detection step for at least two light sources belonging to at least two of the groups. and a correction step of correcting the timing, wherein each of the plurality of light source groups has a representative light source selected from among the plurality of light sources belonging to the light source group, and the plurality of light source groups has at least two representative light sources. and the exposure unit includes a plurality of substrates formed with a plurality of light sources belonging to at least one of the plurality of light source groups, and at least one light source group included in each of the plurality of substrates is a substrate representative group. each of the plurality of light source groups has a representative light source selected from among the plurality of light sources belonging to the light source group; determining a first correction amount for correcting the light emission timing of the plurality of light sources formed on the substrate for each of the plurality of substrates, based on the detected substrate distance between the plurality of irradiation positions in the sub-scanning direction; include.

1 is a perspective view showing the appearance of an MFP according to a first embodiment; FIG. 2 is a block diagram showing an overview of the hardware configuration of the MFP according to the first embodiment; FIG. 2 is a schematic cross-sectional view showing the internal configuration of the MFP; FIG. It is a perspective view showing an example of an internal configuration of an exposure device. It is a top view of the state which combined three 1st light source boards, a 2nd light source board, and a 3rd light source board. It is a top view of a microlens array. FIG. 4 is a side view showing the internal configuration of the microlens array; FIG. 4 is a first diagram schematically showing the relationship between the positions of a plurality of light sources and the irradiation positions on the photosensitive drum; FIG. 7 is a second diagram schematically showing the relationship between the positions of a plurality of light sources and the irradiation positions on the photosensitive drum; 4 is a bottom view of the intermediate transfer belt; FIG. 3 is a block diagram showing an example of functions of a CPU included in the MFP according to the first embodiment; FIG. FIG. 3 is a diagram illustrating an example of detailed functions of a correction unit according to the first embodiment; FIG. It is a figure which shows an example of irradiation position data. It is a figure which shows an example of irradiation distance. 7 is a flowchart showing an example of the flow of light emission timing correction processing; It is a figure which shows an example of the detailed function of the correction|amendment part in a 1st modification. It is a figure which shows an example of the irradiation position data in a 1st modification. It is a figure which shows an example of a representative distance. It is a figure which shows an example of the irradiation distance after prediction. FIG. 11 is a flowchart showing an example of the flow of light emission timing correction processing in the first modified example; FIG. FIG. 11 is a block diagram showing an example of functions of a CPU included in an MFP in a second modified example; FIG. 11 is a block diagram showing an example of detailed functions of a correction unit in a second modified example; 4 is a block diagram showing an example of detailed functions of a substrate distance calculator; FIG. FIG. 13 is a flowchart showing an example of the flow of light emission timing correction processing in the third modified example; FIG. 9 is a flowchart showing an example of the flow of first correction amount determination processing; FIG. 13 is a block diagram showing an example of detailed functions of a correction unit in a fourth modified example; FIG. 16 is a flowchart showing an example of the flow of light emission timing correction processing in the fourth modified example; FIG. 9 is a flowchart showing an example of the flow of second correction amount determination processing; It is a bottom view of the intermediate transfer belt in the second embodiment. FIG. 11 is a block diagram showing an example of functions of a CPU included in the MFP according to the second embodiment; FIG. FIG. 10 is a diagram illustrating an example of detailed functions of a correction unit according to the second embodiment; FIG. It is a figure which shows an example of 1st irradiation position data. It is a figure which shows an example of 2nd irradiation position data. FIG. 4 is a schematic diagram showing an example of the arrangement state of a standard substrate and a reference substrate; FIG. 11 is a flowchart showing an example of the flow of light emission timing correction processing in the second embodiment; FIG. FIG. 11 is a flowchart showing an example of the flow of first correction amount determination processing in the second embodiment; FIG. 7 is a flow chart showing an example of the flow of a light source-by-light source first correction amount determination process; FIG. 14 is a diagram showing an example of detailed functions of a correction unit in a fifth modified example;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are given the same reference numerals. Their names and functions are also the same. A detailed description thereof will therefore not be repeated.

FIG. 1 is a perspective view showing the appearance of the MFP according to the first embodiment. FIG. 2 is a block diagram outlining the hardware configuration of the MFP according to the first embodiment. 1 and 2, MFP (Multi Function Peripheral) 100 is an example of an image forming apparatus, and includes main circuit 110, document reading section 130 for reading a document, and document reading section 130 for reading a document. An automatic document feeder 120 for transporting, an image forming unit 140 for forming an image on a sheet based on image data, a paper feeding unit 150 for supplying paper to the image forming unit 140, and a user interface. and an operation panel 160 of.

The automatic document feeder 120 automatically conveys a plurality of documents set on the document tray 125 one by one to the document reading position of the document reading section 130, and the image formed on the document by the document reading section 130 is displayed. The read document is discharged onto the document discharge tray 127 .

Document reading unit 130 has a rectangular reading surface for reading a document. The reading surface is formed of platen glass, for example. Automatic document feeder 120 is connected to the main body of MFP 100 so as to be rotatable about an axis parallel to one side of the reading surface, and can be opened and closed. A document reading unit 130 is arranged below the automatic document feeder 120, and the reading surface of the document reading unit 130 is exposed when the automatic document feeder 120 is rotated and opened. Therefore, the user can place the document on the reading surface of the document reading unit 130 . The automatic document feeder 120 can change its state between an open state in which the reading surface of the document reading unit 130 is exposed and a closed state in which the reading surface is covered.

The image forming section 140 is controlled by the CPU 111 and forms an image on a sheet conveyed by the paper feeding section 150 by a well-known electrophotographic method. In this embodiment, image forming section 140 forms an image on a sheet conveyed by sheet feeding section 150 under image data input from CPU 111 and image forming conditions corresponding to the medium type of the sheet. The sheet on which the image has been formed is discharged to the discharge tray 159 . The image data output by CPU 111 to image forming portion 140 includes image data input from document reading portion 130 as well as image data such as print data received from the outside.

The main circuit 110 includes a CPU (Central Processing Unit) 111 that controls the entire MFP 100, a communication interface (I/F) section 112, a ROM (Read Only Memory) 113, a RAM (Random Access Memory) 114, It includes a hard disk drive (HDD) 115 as a mass storage device, a facsimile section 116 and an external storage device 118 . CPU 111 is connected to automatic document feeder 120 , document reading portion 130 , image forming portion 140 , paper feeding portion 150 and operation panel 160 , and controls MFP 100 as a whole.

ROM 113 stores a program executed by CPU 111 or data necessary for executing the program. The RAM 114 is used as a work area when the CPU 111 executes programs. RAM 114 also temporarily stores image data continuously sent from document reading unit 130 .

Operation panel 160 is provided above MFP 100 . Operation panel 160 includes a display portion 161 and an operation portion 163 . The display unit 161 is, for example, a liquid crystal display (LCD), and displays an instruction menu for the user, information about acquired image data, and the like. Note that an organic EL (electroluminescence) display, for example, can be used instead of the LCD as long as it is a device that displays an image.

Operation portion 163 includes a touch panel 165 and a hard key portion 167 . The touch panel 165 is of a capacitive type. It should be noted that the touch panel 165 is not limited to the capacitive method, and other methods such as a resistive film method, a surface acoustic wave method, an infrared method, an electromagnetic induction method, and the like can be used.

Touch panel 165 is provided so that its detection surface overlaps display unit 161 on the upper surface or the lower surface of display unit 161 . Here, the size of the detection surface of the touch panel 165 and the size of the display surface of the display unit 161 are the same. Therefore, the coordinate system of the display surface and the coordinate system of the detection surface are the same. Touch panel 165 detects a position where the user points to the display surface of display unit 161 on the detection surface, and outputs the coordinates of the detected position to CPU 111 . Since the coordinate system of the display surface and the coordinate system of the detection surface are the same, the coordinates output by touch panel 165 can be replaced with the coordinates of the display surface.

Hard key portion 167 includes a plurality of hard keys. A hard key is, for example, a contact switch. Touch panel 165 detects the position designated by the user on the display surface of display unit 161 . When the user operates MFP 100, it is often the case that the user is in an upright posture. Therefore, the display surface of display unit 161, the operation surface of touch panel 165, and hard key unit 167 are arranged facing upward. This is so that the user can easily view the display surface of the display unit 161 and can easily indicate the operation unit 163 with his or her finger.

Communication I/F unit 112 is an interface for connecting MFP 100 to a network. Communication I/F unit 112 communicates with other computers or data processing devices connected to a network using a communication protocol such as TCP (Transmission Control Protocol) or FTP (File Transfer Protocol). A network to which communication I/F unit 112 is connected is a local area network (LAN), and the form of connection may be wired or wireless. Also, the network is not limited to a LAN, and may be a wide area network (WAN), a public switched telephone network (PSTN), the Internet, or the like.

Facsimile unit 116 is connected to the public switched telephone network (PSTN) and transmits facsimile data to or receives facsimile data from the PSTN. Facsimile unit 116 stores the received facsimile data in HDD 115 , converts it into print data that can be printed by image forming unit 140 , and outputs the print data to image forming unit 140 . Accordingly, image forming section 140 forms an image of the facsimile data received by facsimile section 116 on paper. Further, facsimile section 116 converts data stored in HDD 115 into facsimile data and transmits the facsimile data to a facsimile machine connected to the PSTN.

The external storage device 118 is controlled by the CPU 111 and is equipped with a CD-ROM (Compact Disk Read Only Memory) 118A or a semiconductor memory. In this embodiment, an example in which CPU 111 executes a program stored in ROM 113 will be described. , the read program may be stored in the RAM 114 and executed.

The recording medium for storing the program to be executed by the CPU 111 is not limited to the CD-ROM 118A, but may be a flexible disk, a cassette tape, an optical disk (MO (Magnetic Optical Disc)/MD (Mini Disc)/DVD (Digital Versatile Disc). )), an IC card, an optical card, a mask ROM, a semiconductor memory such as an EPROM (Erasable Programmable ROM), or the like. Furthermore, the CPU 111 downloads the program from a computer connected to the network and stores it in the HDD 115, or the computer connected to the network writes the program to the HDD 115 and loads the program stored in the HDD 115 into the RAM 114. and executed by the CPU 111. The programs here include not only programs directly executable by the CPU 111, but also source programs, compressed programs, encrypted programs, and the like.

FIG. 3 is a schematic cross-sectional view showing the internal configuration of the MFP. Referring to FIG. 3, automatic document feeder 120 separates one or more documents placed on document tray 125 and conveys them to document reading unit 130 one by one. The document reading unit 130 exposes the image of the document set on the document glass 11 by the automatic document feeder 120 with the exposure lamp 13 attached to the slider 12 moving below. Reflected light from the document is guided to a lens 16 by a mirror 14 and two reflecting mirrors 15 and 15A, and forms an image on a CCD (Charge Coupled Devices) sensor 18 . The exposure lamp 13 and the mirror 14 are attached to a slider 12, which is moved by the scanner motor 17 in the arrow direction (sub-scanning direction) shown in FIG. As a result, the entire surface of the document set on the document glass 11 can be scanned. As the exposure lamp 13 and the mirror 14 move, the two reflection mirrors 15 and 15A move in the arrow direction in FIG. 2 at a speed of V/2. As a result, the optical path length from the light irradiated onto the document by the exposure lamp 13 after being reflected by the document to forming an image on the CCD sensor 18 is always constant. When the operation mode is switched from the power saving mode to the normal mode, the document reading unit 130 executes shading correction as initialization processing and moves the slider 12 to a predetermined position.

The reflected light imaged on the CCD sensor 18 is converted into image data as an electrical signal within the CCD sensor 18 and sent to the main circuit 110 . Main circuit 110 performs A/D conversion processing, digital image processing, and the like on the received analog image data, and then outputs the data to image forming section 140 . Main circuit 110 converts the image data into cyan (C), magenta (M), yellow (Y), and black (K) print data, and outputs the data to image forming section 140 .

Image forming section 140 includes image forming units 20Y, 20M, 20C, and 20K for yellow, magenta, cyan, and black, respectively. Here, "Y", "M", "C" and "K" represent yellow, magenta, cyan and black respectively. An image is formed by driving at least one of the image forming units 20Y, 20M, 20C, and 20K. When all of the image forming units 20Y, 20M, 20C and 20K are driven, a full color image is formed. Yellow, magenta, cyan and black printing data are input to the image forming units 20Y, 20M, 20C and 20K, respectively. Since the image forming units 20Y, 20M, 20C, and 20K differ only in the color of the toner they handle, the image forming unit 20Y for forming a yellow image will be described here.

The image forming unit 20Y includes an exposure device 21Y to which yellow print data is input, a photosensitive drum 23Y as an image carrier of the exposure device 21Y, a charging charger 22Y, a developing device 24Y, a transfer charger 25Y, and a toner bottle 41Y. The toner bottle 41Y stores yellow toner.

The exposure device 21Y emits light according to the printing data (electrical signal) received from the main circuit 110, and exposes the photosensitive drum 23Y, which is the subject. After being charged by the charging charger 22Y, the photosensitive drum 23Y is irradiated with laser light emitted by the exposure device 21Y. Thereby, an electrostatic latent image is formed on the photosensitive drum 23Y. Subsequently, the developing device 24Y places toner supplied from the toner bottle 41Y on the electrostatic latent image to form a toner image. The toner image formed on the photosensitive drum 23Y is transferred onto the intermediate transfer belt 30 by the transfer charger 25Y.

On the other hand, the intermediate transfer belt 30 is suspended by the drive roller 33C and the roller 33A so as not to loosen. When the driving roller 33C rotates counterclockwise in FIG. 3, the intermediate transfer belt 30 rotates counterclockwise in the figure at a predetermined speed. As the intermediate transfer belt 30 rotates, the roller 33A rotates counterclockwise.

As a result, the image forming units 20Y, 20M, 20C, and 20K transfer the toner images onto the intermediate transfer belt 30 in order. The timing at which each of the image forming units 20Y, 20M, 20C, and 20K transfers the toner image onto the intermediate transfer belt 30 is adjusted by detecting a reference mark attached to the intermediate transfer belt 30. FIG. As a result, yellow, magenta, cyan, and black toner images are superimposed on the intermediate transfer belt 30 .

The toner image formed on the intermediate transfer belt 30 is transferred onto the paper by the transfer roller 26 . The paper onto which the toner image has been transferred is conveyed to the fixing roller pair 32 and heated by the fixing roller pair 32 . As a result, the toner is melted and fixed on the paper. After that, the paper is discharged to the paper discharge tray 159 .

A registration sensor 39 for reading part of the toner image transferred to the intermediate transfer belt 30 is provided between the image forming unit 20K and the transfer roller 26 . The registration sensor 39 includes a light-projecting portion that emits light toward the intermediate transfer belt 30 and a light-receiving portion that receives the light reflected by the intermediate transfer belt 30, and outputs a signal indicating the amount of light received by the light-receiving portion. Output. Since the registration sensor 39 is provided between the image forming unit 20K and the transfer roller 26, it can read the toner images formed on the intermediate transfer belt 30 by each of the image forming units 20Y, 20M, 20C, and 20K. . The registration sensor 39 can detect toner images of respective colors of yellow, magenta, cyan, and black.

A removing device 28 is provided on the intermediate transfer belt 30 upstream of the image forming unit 20Y. The removing device 28 removes toner remaining on the intermediate transfer belt 30 .

Sheets of different sizes are set in the sheet feed cassettes 35, 35A, and 35B. Sheets stored in paper feed cassettes 35, 35A, and 35B are supplied to the conveying path by take-out rollers 36, 36A, and 36B attached to paper feed cassettes 35, 35A, and 35B, respectively, and are fed by paper feed roller 37. It is sent to timing roller 31 .

MFP 100 drives all of image forming units 20Y, 20M, 20C, and 20K when forming a full-color image. drive one. Also, two or more of the image forming units 20Y, 20M, 20C, and 20K can be combined to form an image. Here, a tandem type MFP 100 having image forming units 20Y, 20M, 20C, and 20K that form toners of four colors on a sheet of paper will be described. It may be a 4-cycle type MFP that transfers to .

Next, the exposure devices 21Y, 21M, 21C and 21K will be described. Since the exposure devices 21Y, 21M, 21C, and 21K are all the same, the exposure device 21Y will be described as an example here.

FIG. 4 is a perspective view showing an example of the internal configuration of the exposure apparatus. Referring to FIG. 4, exposure device 21Y includes an exposure unit including three first light source substrates 201, second light source substrate 202 and third light source substrate 203, and microlens array 240. Microlens array 240 includes a plurality of lens sets 245 . A plurality of light sources 200 are formed on each of the first light source substrate 201 , the second light source substrate 202 and the third light source substrate 203 . The first light source substrate 201, the second light source substrate 202, and the third light source substrate 203 are arranged so as to overlap with each other while shifting in the sub-scanning direction. A second light source substrate 202 is arranged below the first light source substrate 201 , and a third light source substrate 203 is arranged above the first light source substrate 201 . A portion of the first light source substrate 201 and a portion of the second light source substrate 202 overlap, and a portion of the first light source substrate 201 and a portion of the third light source substrate 203 overlap. The formation area of the second light source substrate 202 where the light sources 200 are formed does not overlap with the first light source substrate 201 . The formation area of the first light source substrate 201 where the light sources 200 are formed does not overlap with the third light source substrate 203 . Therefore, the light emitted from the plurality of light sources 200 respectively formed on the first light source substrate 201, the second light source substrate 202, and the third light source substrate 203 is emitted from the first light source substrate 201, the second light source substrate 202, and the third light source substrate. The light is irradiated toward the lens set 245 provided in the microlens array 240 so as to face each of the substrates 203 .

FIG. 5 is a plan view of a state in which three first light source substrates, second light source substrates, and third light source substrates are combined. Referring to FIG. 5 , a plurality of light sources 200 formed on first light source substrate 201 belong to one of three light source groups 211 , 212 and 213 . The plurality of light sources 200 belonging to the light source group 211 are arranged along the main scanning direction and are positioned at the same position in the sub-scanning direction perpendicular to the main scanning direction. The plurality of light sources 200 belonging to the light source group 212 are arranged along the main scanning direction and have the same position in the sub-scanning direction. The plurality of light sources 200 belonging to the light source group 213 are arranged along the main scanning direction and have the same position in the sub-scanning direction. The light source groups 211, 212, and 213 on the first light source substrate 201 are arranged along the sub-scanning direction, with the light source group 211 arranged most upstream in the sub-scanning direction and the light source group 213 arranged most downstream in the sub-scanning direction. be done.

A plurality of light sources 200 formed on the second light source substrate 202 belong to one of three light source groups 221 , 222 and 223 . The plurality of light sources 200 belonging to the light source group 221 are arranged along the main scanning direction and have the same position in the sub-scanning direction. The plurality of light sources 200 belonging to the light source group 222 are arranged along the main scanning direction and have the same position in the sub-scanning direction. The plurality of light sources 200 belonging to the light source group 223 are arranged along the main scanning direction and have the same position in the sub-scanning direction. The light source groups 221, 222, and 223 on the second light source substrate 202 are arranged along the sub-scanning direction, with the light source group 221 arranged most upstream in the sub-scanning direction and the light source group 223 arranged most downstream in the sub-scanning direction. be done.

A plurality of light sources 200 formed on the third light source substrate 203 belong to one of three light source groups 231 , 232 and 233 . The plurality of light sources 200 belonging to the light source group 231 are arranged along the main scanning direction and have the same position in the sub-scanning direction. The plurality of light sources 200 belonging to the light source group 232 are arranged along the main scanning direction and have the same position in the sub-scanning direction. The plurality of light sources 200 belonging to the light source group 233 are arranged along the main scanning direction and have the same position in the sub-scanning direction. The light source groups 211, 212, and 213 are arranged along the sub-scanning direction, with the light source group 231 arranged furthest upstream in the sub-scanning direction and the light source group 233 arranged furthest downstream in the sub-scanning direction.

The first light sources are arranged such that the light source group 221 included in the second light source substrate 202 is arranged furthest upstream in the sub-scanning direction, and the light source group 233 included in the third light source substrate 203 is arranged furthest downstream in the sub-scanning direction. A substrate 201, a second light source substrate 202 and a third light source substrate 203 are positioned. Here, the light source groups 211, 212, and 213 included in the first light source substrate 201, the light source groups 221, 222, and 223 included in the second light source substrate 202, and the light source groups 231, 232, and 233 included in the third light source substrate 203 Each position is indicated in the Nth column (N is a positive integer) using the order from the upstream side in the sub-scanning direction. Specifically, the light source group 221 included in the second light source substrate 202 is the most upstream side in the sub-scanning direction, so it is in the first row, and the light source group 233 included in the third light source substrate 203 is the most downstream side, so it is in the ninth row. column. The fifth row, which is arranged in the sub-scanning direction in the middle, is the light source group 212 of the first light source substrate 201 .

The first light source board 201 includes three light source groups 211, 212, and 213, the second light source board 202 includes three light source groups 221, 222, and 223, and the third light source board 203 includes light source groups 231, 232, 233, but the number of light source groups included in one light source substrate is not limited to this, and may be determined according to the size of the lens set described later, and may be one or more.

A plurality of light sources 200 formed on the first light source substrate 201 are classified into one of a plurality of lens groups. A predetermined number of light sources classified into one lens group among the plurality of light sources 200 belonging to the light source group 211 are arranged continuously at equal intervals in the main scanning direction. A predetermined number of light sources classified into one lens group among the plurality of light sources 200 belonging to the light source group 212 are arranged continuously in the main scanning direction at regular intervals. A predetermined number of light sources classified into one lens group among the plurality of light sources 200 belonging to the light source group 213 are arranged continuously at equal intervals in the main scanning direction.

In the present embodiment, the predetermined number is 3. On the first light source substrate 201, three light sources 200 out of the plurality of light sources 200 belonging to the light source group 211 and three out of the plurality of light sources 200 belonging to the light source group 212 One light source 200 and three light sources 200 out of the plurality of light sources 200 belonging to the light source group 213 belong to the first lens group 241A. Among the nine light sources 200 included in the first lens group 241A, the light source 200 belonging to the light source group 212 arranged at the center in the sub-scanning direction among the light source groups 211, 212, and 213, and the light source 200 at the center in the main scanning direction. is the center of the first lens group 241A. Since each of the light source groups 211, 212, and 213 includes more than the predetermined number of light sources 200, 3, the first light source substrate 201 has a plurality of first lens groups 241A arranged along the main scanning direction.

Although the number of light sources 200 included in one first lens group 241A among the plurality of light sources 200 included in each of the light source groups 211, 212, and 213 is three, the predetermined number is not limited to this. , may be determined according to the size of the lens set, and may be 1 or more.

Similarly, in the second light source substrate 202, three light sources 200 out of the plurality of light sources 200 belonging to the light source group 221, three light sources 200 out of the plurality of light sources 200 belonging to the light source group 222, and a plurality of light sources 200 belonging to the light source group 223 of the light sources 200 belong to the second lens group 242A. Among the nine light sources 200 included in the second lens group 242A, the light source 200 belonging to the light source group 222 arranged at the center in the sub-scanning direction among the light source groups 221, 222, and 223, and the light source 200 at the center in the main scanning direction. is the center of the second lens group 242A. In the second light source substrate 202, a plurality of second lens groups 242A are arranged along the main scanning direction.

Similarly, in the third light source substrate 203, three light sources 200 out of the plurality of light sources 200 belonging to the light source group 231, three light sources 200 out of the plurality of light sources 200 belonging to the light source group 232, and a plurality of light sources 200 belonging to the light source group 233 of the light sources 200 belong to the second lens group 242A. Among the nine light sources 200 included in the third lens group 243A, the light source 200 belonging to the light source group 232 arranged in the center in the sub-scanning direction among the light source groups 231, 232, and 233, and the light source 200 in the center in the main scanning direction. is the center of the third lens group 243A. In the third light source substrate 203, a plurality of third lens groups 243A are arranged along the main scanning direction.

FIG. 6 is a plan view of a microlens array. Referring to FIG. 6, microlens array 240 includes multiple lens sets 245 . The multiple lens sets 245 are arranged such that the optical axes are positioned at different positions in the main scanning direction and the sub-scanning direction. The plurality of lens sets 245 correspond to the plurality of lens groups included in the first light source substrate 201, the second light source substrate 202 and the third light source substrate 203, respectively.

Specifically, the multiple lens sets 245 belong to one of the first column group 241 , the second column group 242 and the third column group 243 . A plurality of lens sets 245 corresponding to a plurality of first lens groups 241</b>A included in the first light source substrate 201 are classified into the first row group 241 . A plurality of lens sets 245 corresponding to a plurality of second lens groups 242</b>A included in the second light source substrate 202 are classified into the second row group 242 . A plurality of lens sets 245 corresponding to a plurality of third lens groups 243A included in the third light source substrate 203 are classified into the third column group 243 .

A plurality of lens sets 245 belonging to the first row group 241 respectively correspond to a plurality of first lens groups 241A. A plurality of lens sets 245 belonging to the first row group 241 are arranged such that the optical axis of the lens set 245 passes through the light source 200 at the center of the first lens group 241A corresponding to the lens set 245 . A plurality of lens sets 245 corresponding to the plurality of second lens groups 242A are arranged so that the optical axis of the lens set 245 passes through the light source 200 in the center of the second lens group 242A corresponding to the lens set 245. be. A plurality of lens sets 245 corresponding to the plurality of third lens groups 243A are arranged so that the optical axis of the lens set 245 passes through the light source 200 at the center of the third lens group 243A corresponding to the lens set 245. be.

Therefore, the multiple lens sets 245 belonging to the first row group 241 are arranged along the main scanning direction. A plurality of lens sets 245 belonging to the second row group 242 are arranged along the main scanning direction. A plurality of lens sets 245 belonging to the third row group 243 are arranged along the main scanning direction.

FIG. 7 is a side view showing the internal configuration of the microlens array. 7, the microlens array 240 includes a first lens plate 248, a second lens plate 249, an aperture plate 247 arranged between the first lens plate 248 and the second lens plate 249, including. A first lens 245A of each of the plurality of lens sets 245 is formed on the first lens plate 248 . The second lens plate 249 is formed with the second lenses 245B of the plurality of lens sets 245, respectively. The diaphragm plate 247 is formed with diaphragms 247A corresponding to the plurality of lens sets 245 respectively. The lens set 245 is composed of a first lens 245A, a second lens 245B, and an aperture 247A. Light emitted from the light source 200 enters the first lens 245A and irradiates the diaphragm 247A. Light passing through the diaphragm 247A enters the second lens 245B.

FIG. 8 is a first diagram schematically showing the relationship between the positions of a plurality of light sources and the irradiation positions on the photosensitive drum. FIG. 8 is a diagram of the exposure device viewed from a direction perpendicular to the sub-scanning direction. The light source groups 211, 212, and 213 included in the first light source substrate 201, the light source groups 221, 222, and 223 included in the second light source substrate 202, and the light source groups 231, 232, and 233 included in the third light source substrate 203. , are arranged at different positions in the sub-scanning direction. Therefore, the irradiation positions at which the photosensitive drum 23Y is irradiated with the light emitted from the plurality of light sources 200 at the same timing are the corresponding irradiation positions for the plurality of light sources 200 belonging to the same light source group. For a plurality of light sources 200 belonging to different light source groups but having the same direction, the corresponding irradiation positions are different in the sub-scanning direction.

FIG. 9 is a second diagram schematically showing the relationship between the positions of a plurality of light sources and the irradiation positions on the photosensitive drum. Here, ideal irradiation positions are shown when the light emission timings of the plurality of light sources 200 are adjusted so that the light irradiation positions on the photosensitive drum 23Y are the same in the sub-scanning direction. The numbers shown in each of the first light source substrate 201, the second light source substrate 202, and the third light source substrate 203 indicate the positions of the plurality of light sources 200 and the numbers assigned to the light sources. The numbers indicated on the photosensitive drum 23Y indicate the irradiation position and the number given to the light source 200 corresponding to the irradiation position.

The photosensitive drum 23Y moves at a predetermined speed relative to the exposure device 21Y in the sub-scanning direction. Therefore, by shifting the light emission timing of the plurality of light sources 200 for each light source group, the irradiation positions of the plurality of light sources 200 can be set at the same position in the sub-scanning direction. It can be arranged along the scanning direction.

On the second light source substrate 202, three light sources 200 numbered 1, 4 and 7 belonging to the light source group 221 in the first row and the second light source 200 belonging to the light source group 222 in the second row. three light sources 200 numbered No., 5 and 8, and three light sources numbered 3, 6 and 9 belonging to the light source group 223 of the third row. 200 and belong to the second lens group 242A. The plurality of light sources 200 belonging to the light source group 221 in the first row are caused to emit light simultaneously, and after a predetermined time has elapsed, the plurality of light sources 200 belonging to the light source group 222 in the second row are caused to emit light simultaneously. to emit light from the plurality of light sources 200 belonging to the light source group 223 of . As a result, the irradiation positions on the photosensitive drum 23Y corresponding to the first to ninth light sources 200 on the photosensitive drum 23Y become the same in the sub-scanning direction and arranged along the main scanning direction.

On the first light source substrate 201, three light sources 200 numbered 10, 13 and 16 belonging to the light source group 211 in the fourth column and the 11th light source belonging to the light source group 212 in the fifth column. three light sources 200 numbered No., 14 and 17, and three light sources numbered 12, 15 and 18 belonging to the light source group 213 of the sixth row. 200 and belong to the first lens group 241A. The plurality of light sources 200 belonging to the light source group 211 in the fourth column are caused to emit light simultaneously, and after a predetermined time has elapsed, the plurality of light sources 200 belonging to the light source group 212 in the fifth column are caused to emit light simultaneously. to emit light from the plurality of light sources 200 belonging to the light source group 213 of . As a result, the irradiation positions on the photosensitive drum 23Y corresponding to the 10th to 18th light sources 200 on the photosensitive drum 23Y become the same in the sub-scanning direction.

On the third light source substrate 203, three light sources 200 numbered 19th, 22nd and 25th belonging to the light source group 231 in the seventh column and the 20th light source belonging to the light source group 232 in the eighth column. three light sources 200 numbered No., 23 and 26, and three light sources numbered 21, 24 and 27 belonging to the light source group 233 of the ninth column. 200 and belong to the third lens group 243A. The plurality of light sources 200 belonging to the light source group 231 in the seventh column are caused to emit light at the same time. to emit light from the plurality of light sources 200 belonging to the light source group 233 of . As a result, the irradiation positions on the photosensitive drum 23Y corresponding to the 19th to 27th light sources 200 on the photosensitive drum 23Y become the same in the sub-scanning direction.

FIG. 10 is a bottom view of the intermediate transfer belt. The registration sensor 39 is arranged at the end of the intermediate transfer belt 30 in the main scanning direction. Therefore, the registration sensor 39 can read the toner image in a partial area in the main scanning direction of the toner image formed on the intermediate transfer belt 30 . Here, the registration sensor 39 is arranged at a position where the toner images formed at the irradiation positions corresponding to the first to twenty-seventh light sources 200 can be read.

FIG. 11 is a block diagram showing an example of functions of a CPU included in the MFP according to the first embodiment. The functions shown in FIG. 11 are formed in CPU 111 of MFP 100 by executing the light emission timing correction program. Referring to FIG. 11 , CPU 111 provided in MFP 100 includes sensor control portion 51 , detection portion 53 , correction portion 55 and exposure control portion 57 .

The exposure controller 57 controls the exposure devices 21Y, 21M, 21C, and 21K. The exposure control unit 57 causes the plurality of light sources 200 included in the exposure devices 21Y, 21M, 21C, and 21K to emit light according to the printing data input thereto. The print data is data in which a plurality of pixels are arranged in the main scanning direction and the sub-scanning direction.

The detection unit 53 detects irradiation positions at which the light emitted from the plurality of light sources 200 included in the exposure devices 21Y, 21M, 21C, and 21K is irradiated onto the photosensitive drums 23Y, 23M, 23C, and 23K. Specifically, the detection unit 53 outputs test data to the exposure control unit 57, and causes the exposure devices 21Y, 21M, 21C, and 21K to irradiate light according to the test data. The test data is print data corresponding to each of the four colors of yellow, cyan, magenta, and black. The test data preferably contains images of straight lines parallel to the main scanning direction.

Since the detection unit 53 detects the irradiation positions corresponding to the exposure devices 21Y, 21M, 21C, and 21K in the same manner, the exposure device 21Y will be described as an example. Yellow test data is input to the exposure device 21Y.

Toner is deposited by the developing device 24Y on the irradiation position where the photosensitive drum 23Y is irradiated with the light emitted from the plurality of light sources 200 included in the exposure device 21Y. The image forming unit 140 rotates the drive roller 33C so that the intermediate transfer belt 30 moves in the sub-scanning direction at a predetermined image forming speed, and the portion of the photosensitive drum 23Y that contacts the intermediate transfer belt 30 is predetermined. The photosensitive drum 23Y is rotated so as to move in the sub-scanning direction at the image forming speed. Therefore, when the toner-attached portion of the photoreceptor drum 23Y moves to a predetermined position with respect to the intermediate transfer belt 30, the toner attached to the photoreceptor drum 23Y is transferred to the intermediate transfer belt 30 and transferred to the intermediate transfer belt 30. A toner image is formed on the transfer belt 30 .

The detection unit 53 outputs a reading instruction to the sensor control unit 51 to read the toner image formed on the intermediate transfer belt 30 . The sensor control unit 51 controls the registration sensor 39 to read the toner image formed on the intermediate transfer belt 30 and acquires read data output from the registration sensor 39 . The sensor control section 51 outputs the acquired read data to the detection section 53 .

Based on the read data input from the sensor control unit 51, the detection unit 53 detects the irradiation position where the light emitted from each of the plurality of light sources 200 included in the exposure device 21Y is irradiated onto the photosensitive drum 23Y. The irradiation position is expressed in a coordinate space whose coordinate axes are the main scanning direction and the sub-scanning direction.

The images of straight lines parallel to the main scanning direction included in the yellow test data include images corresponding to at least the first to twenty-seventh light sources 200 among the plurality of light sources included in the exposure device 21Y. Therefore, the detection unit 53 uses the read data output from the registration sensor 39 to detect the irradiation position of the light emitted by each of the first to twenty-seventh light sources 200 of the exposure device 21Y. The detection unit 53 outputs to the correction unit 55 irradiation position data indicating the first to twenty-seventh irradiation positions detected corresponding to the first to twenty-seventh light sources 200 included in the exposure device 21Y. . In the read data, the brightness of the pixels on which the toner image is formed is lower than the brightness of the pixels on which the toner image is not formed. On the other hand, the positions in the main scanning direction are determined in advance at the irradiation positions corresponding to the first to twenty-seventh light sources 200 . For this reason, the irradiation positions corresponding to the first to twenty-seventh light sources 200 are specified as positions of pixel values at predetermined positions in the main scanning direction where the lightness is low.

Ideally, the irradiation position of the light emitted by each of the first to twenty-seventh light sources 200 of the exposure device 21Y is a straight line parallel to the main scanning direction on the photosensitive drum 23Y. Therefore, the 1st to 27th irradiation positions indicated by the irradiation position data should be at the same position in the sub-scanning direction. However, the relative positions of the first light source substrate 201, the second light source substrate 202 and the third light source substrate 203 are shifted, and the relative positions of the first light source substrate 201, the second light source substrate 202 and the third light source substrate 203 and the photosensitive drum 23Y. Due to a positional deviation or the like, the first to twenty-seventh irradiation positions may not be the same in the sub-scanning direction.

The correction unit 55 emits light from the plurality of light sources 200 included in the exposure device 21Y based on the irradiation distance in the sub-scanning direction between at least two of the plurality of irradiation positions indicated by the irradiation position data input from the detection unit 53. A correction amount for correcting the timing is determined.

The MFP 100 according to the present embodiment corrects the light emission timing for each of the light source groups on the premise that the plurality of irradiation positions corresponding to the plurality of light sources 200 belonging to one light source group are the same in the sub-scanning direction. . Based on the irradiation distance in the sub-scanning direction between at least two irradiation positions respectively corresponding to at least two light sources 200 belonging to at least two of a plurality of light source groups among the plurality of light sources 200, the correction unit 55 calculates a plurality of A correction amount for correcting the light emission timing of the light source is determined. Specifically, the correction unit 55 determines the correction amount for each of the plurality of light source groups, and outputs the correction amount for each of the plurality of light source groups to the exposure control unit 57 .

The exposure control unit 57 corrects the light emission timing of the plurality of light sources 200 included in each of the exposure devices 21Y, 21M, 21C, and 21K based on the correction amount for each of the plurality of light source groups input from the correction unit 55 . For example, the exposure control unit 57 corrects the light emission timings of the plurality of light sources 200 belonging to the light source group 211 using the correction amount of the light source group 211 . If the correction amount is positive, the light emission timing is delayed by the correction amount, and if the correction amount is negative, the light emission timing is advanced by the correction amount.

12 is a diagram illustrating an example of detailed functions of a correction unit according to the first embodiment; FIG. Correction unit 55 includes group position acquisition unit 61 , irradiation distance calculation unit 63 , and correction amount determination unit 65 . The group position acquisition unit 61 acquires irradiation positions corresponding to each of the plurality of light source groups. For each of the plurality of light source groups, the group position acquisition unit 61 determines one of the plurality of light sources 200 included in the light source group as the representative light source. Since the irradiation positions corresponding to the plurality of light sources 200 belonging to the same light source group have the same sub-scanning direction, any light source 200 from among the plurality of light sources 200 belonging to the light source group may be determined as the representative light source. . Here, since the irradiation position data includes the irradiation positions corresponding to the first to twenty-seventh light sources 200, three of the first to twenty-seventh light sources 200 included in the target light source group One of the light sources 200 is determined as the representative light source. Here, the group position acquisition unit 61 selects three light sources 200 included in the same lens group among the plurality of light sources 200 included in the light source group and arranged at the center in the main scanning direction. The representative light source of the light source group is determined.

For example, the first light source substrate 201 includes light source groups 211, 212, and 213 in fourth to sixth columns. The group position acquisition unit 61 selects the 13th light source 200 out of the 10th, 13th, and 16th light sources 200 included in the first lens group 241A for the light source group 211 in the fourth row. is determined as the representative light source. Similarly, the group position acquisition unit 61 determines the light source 200 numbered 14 as the representative light source of the light source group 212 in the fifth column, and the light source 200 numbered 15 as the representative light source of the light source group 213 in the sixth column. do.

Similarly, the group position acquisition unit 61 determines the fourth light source 200 as the representative light source of the light source group 221 in the first row, and determines the fifth light source 200 as the representative light source of the second row light source group 222. Then, the sixth light source 200 is determined as the representative light source of the light source group 223 in the third column. The group position acquisition unit 61 determines the light source 200 of No. 22 as the representative light source of the light source group 231 of the seventh column, the light source 200 of No. 23 as the representative light source of the light source group 232 of the eighth column, and the light source group 200 of the eighth column. The 24th light source 200 is determined as the representative light source of the light source group 233 in the 9th column.

The group position acquisition unit 61 determines the irradiation position of the representative light source for each of the plurality of light source groups from the irradiation position data input from the detection unit 53, and sends the irradiation position for each of the plurality of light source groups to the irradiation distance calculation unit 63. Output. Hereinafter, the irradiation position corresponding to the representative light source of the light source group is referred to as the irradiation position of the light source group.

Based on the irradiation positions of the plurality of light source groups input from the group position acquisition unit 61, the irradiation distance calculation unit 63 calculates the distance in the sub-scanning direction between the irradiation positions corresponding to the plurality of light source groups. Calculate as a distance. The irradiation distance calculator 63 includes a reference group position determiner 67 and a reference group position determiner 69 .

The reference group position determination unit 67 sets one of the plurality of light source groups as the reference group. The reference group position determination unit 67 determines the angle at which the line connecting the plurality of light sources 200 formed in the plurality of light source groups and the rotation center of the photoreceptor drum 23Y intersects the surface of the photoreceptor drum 23Y at the most perpendicular angle. Set the approaching light group to the reference group. Here, among the plurality of light source groups 211, 212, 213, 221, 222, 223, 231, 232, and 233, the light source group 212 in the fifth row arranged in the center in the sub-scanning direction is determined as the reference group. The representative light source of the light source group 212, which is the reference group, is the 14th light source 200. FIG.

The reference group position determination unit 67 determines the irradiation position of the reference group among the irradiation positions of the plurality of light source groups input from the group position acquisition unit 61 as the reference group position. Here, the irradiation position of the light source group 212 in the fifth column is determined as the reference group position.

The reference group position determination unit 69 sets light source groups other than the reference group among the plurality of light source groups as reference groups. The reference group position determination unit 69 determines the irradiation position of each light source group, which is a reference group, as a reference group position among the irradiation positions of the plurality of light source groups input from the group position acquisition unit 61 . Here, the irradiation positions of the light source groups 211, 213, 221, 222, 223, 231, 232, and 233 of the 1st to 4th columns and the 6th to 9th columns are determined as reference group positions.

The irradiation distance calculator 63 calculates the distance in the sub-scanning direction between the reference group position and the reference group position for each of the plurality of reference groups as the irradiation distance, and determines the correction amount based on the combination of the reference group and the irradiation distance. Output to unit 65 .

The reference group is the light source group 212 in the fifth column, and the representative light source of the reference group is the light source 200 in the 14th column. Therefore, for example, when the light source group 221 in the first row is set as the reference group, the irradiation distance calculation unit 63 determines that the irradiation position of the fourth light source 200, which is the representative light source of the light source group 221 in the first row, is the reference group. The irradiation position of the 14th light source 200, which is the representative light source of the reference group, is the reference group position. If the reference group position is upstream in the sub-scanning direction from the reference group position, the irradiation distance is a positive value. If the reference position is downstream in the sub-scanning direction from the reference group position, the irradiation distance is negative. be the value of

Based on the irradiation distance of each of the plurality of reference groups input from the irradiation distance calculation unit 63, the correction amount determination unit 65 determines the correction amount for correcting the light emission timing of the plurality of light sources 200 for each of the plurality of reference groups. decide. Here, the plurality of reference groups are the light source groups 211, 213, 221, 222, 223, 231, 232, 233 of the first to fourth columns and the sixth to ninth columns. The correction amount determination unit 65 determines a value obtained by dividing the irradiation distance of the reference group by the image forming speed as the correction amount of the reference group. Also, the correction amount determination unit 65 determines the correction amount of the light source group 212, which is the reference group, to be zero. The correction amount determination section 65 outputs the correction amounts determined for each of the plurality of light source groups 211 , 212 , 213 , 221 , 222 , 223 , 231 , 232 and 233 to the exposure control section 57 .

FIG. 13 is a diagram showing an example of irradiation position data. 13, irradiation positions 211A, 212A, 213A, 221A, 222A, 223A, 231A, 232A, 222A, 223A, 231A, 232A, 211A, 212A, 213A, 232A, 232A, 232A, 212A, 232A, 232A, 232A, 232A, 232A, 232A, 232A, 232A, 232A, 232A, 232A, 232A, 232A, 232A, 232A, 232A, 232A, 232A, 232A, 232A, 233A is shown in black. The three irradiation positions 212A corresponding to the 11th, 14th, and 17th light sources 200 belonging to the light source group 212 in the fifth column, which is the reference group, are the same in the sub-scanning direction and are in the same position in the main scanning direction. are indicated by three black pixels with different . Also, the three irradiation positions 221A corresponding to the first, fourth and seventh light sources 200 belonging to the light source group 221 in the first row have the same positions in the sub-scanning direction but different positions in the main scanning direction. Indicated by three black pixels. Also, the three irradiation positions 233A corresponding to the 21st, 24th and 27th light sources 200 belonging to the light source group 233 of the 9th column are at the same position in the sub-scanning direction and at the same position in the main scanning direction. Indicated by three different black pixels.

The irradiation position 211A of the light source group 211 in the fourth row is shifted upstream by one pixel in the sub-scanning direction with respect to the irradiation position 212A of the light source group 212 in the fifth row, which is the reference group. The irradiation position 213A of the light source group 213 in the sixth row is shifted downstream by one pixel in the sub-scanning direction with respect to the irradiation position 212A of the light source group 212 in the fifth row, which is the reference group.

Similarly, the irradiation position 221A of the light source group 221 in the first row is shifted upstream by 10 pixels in the sub-scanning direction with respect to the irradiation position 212A of the light source group 212 in the fifth row, which is the reference group. The irradiation position 233A of the light source group 233 in the ninth row is shifted downstream by 10 pixels in the sub-scanning direction with respect to the irradiation position 212A of the light source group 212 in the fifth row, which is the reference group.

FIG. 14 is a diagram showing an example of the irradiation distance. Here, the irradiation distance calculated based on the irradiation position data shown in FIG. 13 is shown. In FIG. 14, the light source groups 211, 212, 213, 221, 222, 223, 231, 232, and 233 are indicated by the number of columns in the order in which they are arranged in the sub-scanning direction.

14, the irradiation distance of the light source group 221 in the first row is +10, the irradiation distance of the light source group 222 in the second row is +6, and the irradiation distance of the light source group 223 in the third row is +3. , and the irradiation distance of the light source group 211 in the fourth column is +1. Since the light source group 212 in the fifth column is the reference group, the irradiation distance is zero. The irradiation distance of the light source group 213 in the sixth row is -1, the irradiation distance of the light source group 231 in the seventh row is -3, the irradiation distance of the light source group 232 in the eighth row is -6, and the irradiation distance of the light source group 232 in the eighth row is -6. The throw distance of the column light source group 233 is -10.

FIG. 15 is a flowchart showing an example of the flow of light emission timing correction processing. The light emission timing correction process is a process executed by CPU 111 of MFP 100 when CPU 111 executes a light emission timing correction program. Referring to FIG. 15, CPU 111 causes image forming unit 140 to form an image of test data (step S01). The test data is image data representing straight lines parallel to the main scanning direction for each of the four colors of yellow, magenta, cyan and black. As a result, the image forming units 20Y, 20M, 20C, and 20K form yellow, magenta, cyan, and black toner images corresponding to the images of the test data on the intermediate transfer belt 30, respectively.

In the next step S02, irradiation position data is acquired. The registration sensor 39 is controlled to read the toner image formed on the intermediate transfer belt 30, and read data output from the registration sensor 39 is acquired. Here, read data obtained by reading a yellow toner image will be described as an example. Using the read data for yellow output from the registration sensor 39, the irradiation positions of the first to twenty-seventh light sources 200 of the exposure device 21Y are detected. For each of the first to twenty-seventh light sources 200, by specifying the position in the sub-scanning direction of the pixel whose brightness is low at a predetermined position in the main scanning direction with respect to the light source 200 in the read data, The irradiation position for the light source 200 is specified. By specifying the irradiation position for each of the first to twenty-seventh light sources 200, irradiation position data is obtained.

In step S03, a reference group position is determined. The reference group position is the irradiation position of the representative light source of the reference group. A reference group may be arbitrarily determined from among a plurality of light source groups. Here, the light source group 212 in the fifth column is used as the reference group, and the irradiation position of the light source 200 of number 14, which is the representative light source of the light source group 212, is determined as the reference group position.

In step S04, one of the plurality of light source groups is selected as a processing target, and the process proceeds to step S05. In step S05, it is determined whether or not the light source group selected as the processing target is the reference group. If it is the reference group, the process proceeds to step S10. If not, the light source group to be processed is set as the reference group, and the process proceeds to step S06. In step S06, the reference group position is determined, and the process proceeds to step S07. The reference group position is the irradiation position of the representative light source of the light source group selected for processing. For example, when the light source group 221 in the first column is selected as the processing target, the irradiation position of the fourth light source 200, which is the representative light source of the light source group 221, is determined as the reference group position of the light source group 221.

In step S07, the irradiation distance of the light source group selected as the processing target is calculated. The distance in the sub-scanning direction between the reference group position and the reference group position is calculated as the irradiation distance of the light source group. The irradiation distance is calculated from the reference group position determined in step S06 and the reference group position determined in step S03. The irradiation distance is a positive value when the reference group position is positioned upstream in the sub-scanning direction from the reference group position, and is negative when the reference group position is positioned downstream in the sub-scanning direction from the reference group position. is the value of

In the next step S08, the correction amount of the light source group selected as the processing target is determined, and the process proceeds to step S09. A value obtained by dividing the irradiation distance calculated in step S07 by the image forming speed is determined as a correction amount.

In step S09, the light emission timings of the plurality of light sources 200 included in the light source group selected as the processing target are corrected using the correction amount, and the process proceeds to step S10. If the correction amount is positive, the light emission timing is delayed by the correction amount, and if the correction amount is negative, the light emission timing is advanced by the correction amount.

In step S10, it is determined whether or not there is a light source group that has not been selected as a processing target. If there is an unselected light source group, the process returns to step S04; otherwise, the process ends. Accordingly, by executing steps S05 to S09 for all of the plurality of light source groups, the correction amount of each of the plurality of light source groups is determined, and the light emission timings of the plurality of light sources 200 are corrected. Since the correction amount for the light source group 212 in the fifth column, which is the reference group, is not determined, the light emission timings of the plurality of light sources 200 belonging to the light source group 212 in the fifth column are not corrected.

As described above, MFP 100 in the first embodiment includes exposure devices 21Y, 21M, 21C, and 21K. For example, exposure device 21Y has a plurality of light sources 200 arranged along the main scanning direction. A plurality of light source groups 211, 212, 213, 221, 222, 223, 231, 232, 233 are included. The plurality of light source groups are arranged along the sub-scanning direction such that the positions of the plurality of light sources 200 in the main scanning direction are different from each other. Further, the CPU 111 detects irradiation positions where the light emitted by at least two of the plurality of light sources 200 is irradiated onto the photosensitive drum 23Y moving at a predetermined speed relative to the exposure unit along the sub-scanning direction. included in each of the plurality of light source groups based on the irradiation distance in the sub-scanning direction between at least two irradiation positions detected for at least two light sources belonging to at least two of the plurality of light source groups among the light sources 200 corrects the light emission timing of multiple light sources. Since the plurality of light sources 200 belonging to each of the plurality of light source groups 211, 212, 213, 221, 222, 223, 231, 232, 233 are arranged in the main scanning direction, the plurality of light source groups 211, 212, 213, 221 , 222, 223, 231, 232, and 233 in the sub-scanning direction, each of the plurality of light source groups 211, 212, 213, 221, 222, 223, 231, 232, and 233 in the sub-scanning direction. of the irradiation position can be corrected. As a result, it is possible to reduce the deviation in the sub-scanning direction of the irradiation positions of the plurality of light sources in the exposure device 21Y.

Each of the plurality of light source groups 211, 212, 213, 221, 222, 223, 231, 232, and 233 has a representative light source selected from among the plurality of light sources 200 belonging thereto, and the CPU 111 Based on the irradiation distance in the sub-scanning direction between the irradiation positions corresponding to the representative light sources of the groups, the correction amount for correcting the light emission timing of the plurality of light sources 200 is calculated for the plurality of light source groups 211, 212, 213, 221, 222, 223, 231, 232, 233. Therefore, since it is sufficient to detect the irradiation position corresponding to the representative light source, it is not necessary to detect all the irradiation positions of the plurality of light sources 200, the processing is simplified, and the correction amount can be easily determined.

The plurality of light source groups 211, 212, 213, 221, 222, 223, 231, 232, and 233 are composed of the light source group 212 as a reference group and the light source groups 211, 213, 221, 211, 213, 221, and 212 as reference groups other than the reference group. 222, 223, 231, 232, and 233, and the CPU 111 detects, for example, the reference group position detected as the irradiation position corresponding to the representative light source belonging to the reference group 211 and the irradiation position corresponding to the representative light source belonging to the reference group. A correction amount for correcting the light emission timings of the plurality of light sources 200 belonging to the reference group 211 is determined based on the detected irradiation distance in the sub-scanning direction from the reference group position. Therefore, based on the irradiation distance in the sub-scanning direction between the reference group position with respect to the reference group 211 and the reference group position with respect to the reference group 212, correction for correcting the light emission timings of the plurality of light sources 200 belonging to the reference group 211 is performed. Since the amount is determined, the irradiation positions of the plurality of light sources 200 belonging to the reference group 211 can be matched with the irradiation positions of the plurality of light sources 200 belonging to the reference group 212 .

The reference group 212 is the light source group 212 in which the line connecting the representative light source belonging thereto and the center of rotation of the photoreceptor drum 23Y intersects the surface of the photoreceptor drum 23Y at a perpendicular angle or the most perpendicular angle. Therefore, it is possible to reduce the displacement of the irradiation position of the reference group 212 with respect to the deformation of the photosensitive drum 23Y.

Further, the CPU 111 detects the irradiation position in a state in which the light emitted from the plurality of light sources 200 is emitted at the light emission timing when the light emitted from the plurality of light sources 200 is emitted to the photosensitive drum 23Y at the same position in the sub-scanning direction. do. Therefore, it is sufficient to detect whether or not the irradiation positions of the plurality of light sources 200 are arranged in the main scanning direction, and the light emission timing can be easily corrected.

<First modification>
In the MFP 100 according to the first embodiment, the irradiation positions of the plurality of light source groups 211, 212, 213, 221, 222, 223, 231, 232, 233 are determined, and the plurality of light source groups 211, 212, 213, 221, 222, 223, 231, 232, and 233 are determined.

The MFP 100 in the first modification determines at least two irradiation distances of a plurality of light source groups, and determines a correction amount for each of the plurality of light source groups. The functions of CPU 111 of MFP 100 in the first modification are the same as the functions shown in FIG.

FIG. 16 is a diagram illustrating an example of detailed functions of a correction unit in the first modified example. Referring to FIG. 16, correction unit 55A in the first modification differs from the function shown in FIG. 12 in that irradiation distance calculation unit 63 and correction amount determination unit 65 have The only difference is that the determination unit 65A has been changed, and an arrangement distance acquisition unit 73 has been added. Since other functions are the same as those shown in FIG. 12, the description will not be repeated here.

Referring to FIG. 16 , representative distance calculation portion 63A calculates a representative distance based on the irradiation positions of at least two representative groups among the irradiation positions of each of the plurality of light source groups input from group position acquisition portion 61. . The representative distance is the distance in the sub-scanning direction between at least two irradiation positions respectively corresponding to at least two representative groups. The representative distance calculator 63A includes a reference group position determiner 67A and a reference group position determiner 69A.

The reference group position determination unit 67A sets one of the plurality of light source groups 211, 212, 213, 221, 222, 223, 231, 232, 233 as the reference group. The reference group position determination unit 67A determines that the line connecting the plurality of light sources 200 formed in the plurality of light source groups and the rotation center of the photoreceptor drum 23Y intersects the surface of the image carrier at an angle perpendicular to or at the maximum angle. Set the illuminant group that is near vertical as the base group. Here, among the plurality of light source groups 211, 212, 213, 221, 222, 223, 231, 232, and 233, the light source group 212 in the fifth row arranged in the center in the sub-scanning direction is determined as the reference group. The representative light source of the reference group is light source number 14 200 .

Based on the irradiation position data input from the group position acquisition unit 61, the reference group position determination unit 67A determines the irradiation position of the light source group 212 in the fifth row, which is the reference group, as the reference group position.

The reference group position determination unit 69A sets at least one of the light source groups other than the reference group among the plurality of light source groups 211, 212, 213, 221, 222, 223, 231, 232, and 233 as the reference group. . The reference group may be any light source group other than the reference group. Here, an example will be described in which the light source group 221 in the first row and the light source group 233 in the ninth row, which have the maximum distance from the reference group in the sub-scanning direction, are used as reference groups. Based on the irradiation position data input from the group position acquisition unit 61, the reference group position determination unit 69A determines the irradiation positions of the light source group 221 in the first row and the light source group 233 in the ninth row, which are reference groups. .

The representative distance calculator 63A calculates, for each reference group, the distance in the sub-scanning direction between its irradiation position and the irradiation position of the reference group as a representative distance. If the irradiation position of the reference group is positioned upstream in the sub-scanning direction from the irradiation position of the reference group, the representative distance is set to a positive value, and the irradiation position of the reference group is downstream of the irradiation position of the reference group in the sub-scanning direction. If it is located on the side, the representative distance is set to a negative value. The representative distance calculator 63A outputs a set of the reference group and the representative distance to the correction amount determiner 65A. Here, a set of the light source group 221 in the first column and its representative distance and a set of the light source group 233 in the ninth column and its representative distance are output to the correction amount determination unit 65A.

The reference group is the light source group 212 in the fifth column, and the representative light source of the reference group is the light source 200 in the 14th column. Therefore, the representative distance calculation unit 63A calculates the irradiation position of the fourth light source 200, which is the representative light source of the light source group 221 in the first column, and the irradiation position of the light source 14, which is the representative light source of the light source group 212 in the fifth column. The distance in the sub-scanning direction between the irradiation position of 200 is obtained as the representative distance of the light source group 221 in the first row. Further, the representative distance calculation unit 63A calculates the irradiation position of the 24th light source 200, which is the representative light source of the light source group 233 in the ninth column, and the irradiation position of the 14th light source 200, which is the representative light source of the reference group. The distance in the sub-scanning direction between them is obtained as the representative distance of the light source group 233 in the ninth column.

The arrangement distance acquisition unit 73 acquires relative distances in the sub-scanning direction between the plurality of light source groups as arrangement distances. The relative positions of the multiple light source groups 211, 212, 213, 221, 222, 223, 231, 232, 233 are fixed. Here, the light source group 212 in the fifth column is used as the reference group. The arrangement distance acquisition unit 73 calculates the distances in the sub-scanning direction between each of the plurality of light source groups 211, 213, 221, 222, 223, 231, 232, and 233 and the light source group 212 in the fifth column, which is the reference group. Get as placement distance. The arrangement distance of a light source group is a negative value when the light source group is arranged upstream of the reference group in the sub-scanning direction, and is a negative value when the light source group is arranged downstream of the reference group in the sub-scanning direction. is a positive value. The arrangement distance acquisition section 73 outputs the arrangement distance for each of the plurality of light source groups to the correction amount determination section 65A.

The correction amount determination unit 65A performs correction for correcting the light emission timings of the plurality of light sources 200 based on the representative distance of the reference group input from the representative distance calculation unit 63A and the arrangement distance of each of the plurality of light source groups. A quantity is determined for each of the multiple light source groups. The ratio of the arrangement distance of the light source group to be processed and the arrangement distance of the reference group is used to estimate the value obtained by dividing the representative distance of the reference group as the irradiation distance of the light source group to be processed, and the irradiation distance is used as the image forming speed. is determined as the correction amount corresponding to the light source group to be processed.

For example, when determining the correction amount for the light source group 211 in the fourth column, the correction amount determination unit 65A selects one of the light source groups 221 and 223, which are reference groups. For example, the light source group 221 in the first row, which is closer to the light source group 211 in the fourth row, is selected. Based on the representative distance of the light source group 221 in the first row, the arrangement distance of the light source group 221 in the first row, and the arrangement distance of the light source group 211 in the fourth row, the correction amount determination unit 65A The irradiation distance of the light source group 211 is predicted.

By proportionally distributing the representative distance of the light source groups 221 in the first row in proportion to the arrangement distance of the light source groups 221 in the first row and the arrangement distance of the light source groups 211 in the fourth row, the light source groups 211 in the fourth row to predict the irradiation distance of When the arrangement distance of the light source group 221 in the first row is La, the arrangement distance of the light source group 211 in the fourth row is Lb, and the representative distance of the light source group 221 in the first row is Lc, the light source group 211 in the fourth row is represented by the following formula (1).
LD=Lc×Lb/La×C (1)
However, C is a correction coefficient. The correction coefficient is a predetermined value for Lb. C may be obtained by experiments.

The correction amount determination unit 65A determines a value obtained by dividing the irradiation distance of each of the plurality of light source groups 211, 213, 221, 222, 223, 231, 232, and 233 by the image forming speed as the correction amount.

FIG. 17 is a diagram showing an example of irradiation position data in the first modified example. 17, irradiation positions 221A and 233A corresponding to light source group 221 in the first column and light source group 233 in the ninth column, which are reference groups, and light source group 212 in the fifth column, which is a reference group, The irradiation position 212A is shown in black. The three irradiation positions 212A corresponding to the 11th, 14th, and 17th light sources 200 belonging to the light source group 212 in the fifth column have the same positions in the sub-scanning direction but different positions in the main scanning direction. Indicated by black pixels. Also, the three irradiation positions 221A corresponding to the first, fourth and seventh light sources 200 belonging to the light source group 221 in the first row have the same positions in the sub-scanning direction but different positions in the main scanning direction. Indicated by three black pixels. Also, the three irradiation positions 233A corresponding to the 21st, 24th and 27th light sources 200 belonging to the light source group 233 of the 9th column are at the same position in the sub-scanning direction and at the same position in the main scanning direction. Indicated by three different black pixels.

The irradiation position 221A of the light source group 221 in the first row is shifted upstream by 10 pixels in the sub-scanning direction with respect to the irradiation position 212A of the light source group 212 in the fifth row. The irradiation position 233A of the light source group 233 in the ninth row is shifted downstream by 10 pixels in the sub-scanning direction with respect to the irradiation position 212A of the light source group 212 in the fifth row.

FIG. 18 is a diagram showing an example of representative distances. Here, representative distances calculated based on the irradiation positions shown in FIG. 17 are shown. Referring to FIG. 18, the irradiation distance of the light source group 221 in the first row is +10, the irradiation distance of the light source group 212 in the fifth row is 0 because it is the reference group, and the irradiation distance of the light source group 233 in the ninth row is +10. is -10. The irradiation distances of the light source group 222 in the second row to the light source group 211 in the fourth row and the light source group 213 in the sixth row to the light source group 232 in the eighth row are not determined.

FIG. 19 is a diagram illustrating an example of an irradiation distance after prediction. 19, the predicted irradiation distance of light source group 222 in the second column is +6, the predicted irradiation distance of light source group 223 in the third column is +3, and the predicted irradiation distance of light source group 211 in the fourth column is +6. is +1. The predicted irradiation distance of the light source group 213 in the sixth column is -1, the predicted irradiation distance of the light source group 231 in the seventh column is -3, and the irradiation distance of the light source group 232 in the eighth column is -3. is -6.

FIG. 20 is a flowchart showing an example of the flow of light emission timing correction processing in the first modified example. Referring to FIG. 20, steps S01 to S03 are the same as steps S01 to S03 shown in FIG.

In step S21, a predetermined light source group is selected as a reference group from among the plurality of light source groups, and the process proceeds to step S22. Here, the reference groups are the light source group 211 in the first column and the light source group 233 in the ninth column. One of the light source group 211 in the first column and the light source group 233 in the ninth column, which are reference groups, is selected as a processing target. Here, an example in which the light source group in the first column is selected as the reference group will be described.

In step S22, the irradiation position of the reference group is determined, and the process proceeds to step S23. Determine the irradiation position of the light source group in the first column selected as the reference group. The irradiation position of the light source group is the irradiation position corresponding to the representative light source of the light source group. For example, when the light source group 221 in the first row is selected as the reference group, the irradiation position of the fourth light source 200, which is the representative light source of the light source group 221 in the first row, is determined as the irradiation position of the reference group. do.

In step S23, the representative distance of the reference group is calculated. The distance in the sub-scanning direction between the irradiation position of the reference group and the irradiation position of the reference group is calculated as the representative distance of the reference group. A representative distance is calculated from the irradiation position of the reference group determined in step S22 and the irradiation position of the reference group determined in step S03. The representative distance is a positive value when the irradiation position of the reference group is positioned upstream in the sub-scanning direction from the irradiation position of the reference group, and the irradiation position of the reference group is further in the sub-scanning direction than the irradiation position of the reference group. If it is located on the downstream side, it will have a negative value.

In step S24, it is determined whether or not there is a reference group that has not been selected as a processing target. If there is an unselected reference group, the process returns to step S21; otherwise, the process proceeds to step S25.

In step S25, one of the plurality of light source groups is selected as a processing target, and the process proceeds to step S26. In step S26, it is determined whether or not the light source group selected as the processing target is the reference group. If it is the reference group, the process proceeds to step S30; otherwise, the process proceeds to step S26. In step S26, the arrangement distance is obtained, and the process proceeds to step S27. Here, the arrangement distance of the light source group selected for processing and the arrangement distance of the reference group are acquired. The arrangement distance of the light source group selected for processing is the distance in the sub-scanning direction between the light source group and the reference group, and is a predetermined distance. For example, when the light source group 222 in the second row is selected as the processing target, the distance in the sub-scanning direction between the light source group 222 in the second row and the light source group 212 in the fifth row, which is the reference group, is Determine the distance. Also, the arrangement distance of the reference group is the distance in the sub-scanning direction between the reference group and the reference group, and is a predetermined distance. Here, since the light source group 221 in the first column is used as the reference group, the distance in the sub-scanning direction between the light source group 221 in the first column and the light source group 212 in the fifth column, which is the reference group, is the reference group. Determined as placement distance. Although there are two reference groups, the light source group 221 in the first column and the light source group 233 in the ninth column, the arrangement distance of one of them may be used.

In step S28, the correction amount of the light source group selected as the processing target is calculated. The irradiation distance of the light source group to be processed is predicted using the above equation (1), and the value obtained by dividing the predicted irradiation distance by the image forming speed is determined as the correction amount of the light source group. Since the irradiation distances of the light source group 211 in the first row and the light source group 233 in the ninth row, which are reference groups, are determined as representative distances in step S23, the values obtained by dividing the representative distances by the image forming speed are obtained. Determine the amount of correction.

In step S29, the light emission timings of the plurality of light sources 200 belonging to the light source group selected as the processing target are corrected using the correction amount, and the process proceeds to step S30. If the correction amount is positive, the light emission timing is delayed by the correction amount, and if the correction amount is negative, the light emission timing is advanced by the correction amount.

In step S30, it is determined whether or not there is a light source group that has not been selected as a processing target. If there is an unselected light source group, the process returns to step S25; otherwise, the process ends. Accordingly, by executing steps S25 to S29 for all of the plurality of light source groups, correction amounts for each of the plurality of light source groups 211, 213, 221, 222, 223, 231, 232, and 233 are determined. is corrected. However, since the correction amount for the light source group 212, which is the reference group, is not determined, the light emission timings of the plurality of light sources 200 belonging to the light source group 212 are not corrected.

In the exposure apparatus 21Y in the first modification, the plurality of light source groups 211, 212, 213, 221, 222, 223, 231, 232, 233 include, for example, two representative groups 212, 221, and two representative groups 212 and 221 include a reference group 212 and a reference group 221, and the CPU 111 selects a light source for each of the light source groups 211, 213, 221, 222, 223, 231, 232, and 233, for example, the light source group 211. The arrangement distance between the group 221 and the reference group 212, the arrangement distance between the reference group 221 and the reference group 212, the irradiation position corresponding to the representative light source belonging to the reference group 221, and the representative light source belonging to the reference group 212 A correction amount for correcting the light emission timing of the plurality of light sources 200 formed in the light source group 221 is determined based on the representative distance in the sub-scanning direction between the corresponding irradiation positions. Therefore, since it is sufficient to detect the irradiation positions of at least two representative groups 212 and 221, the irradiation positions corresponding to all of the plurality of light source groups 211, 212, 213, 221, 222, 223, 231, 232, and 233 can be detected. There is no need to detect , the processing is simplified, and the correction amount can be easily determined.

<Second modification>
In the MFP 100 according to the first embodiment, the irradiation positions of the plurality of light source groups 211, 212, 213, 221, 222, 223, 231, 232, 233 are determined, and the plurality of light source groups 211, 212, 213, 221, 222, 223, 231, 232, and 233 are determined.

In MFP 100 in the second modification, the first correction amount is determined for each of first light source substrate 201, second light source substrate 202, and third light source substrate 203. FIG. Then, the MFP 100 corrects the light emission timings of the plurality of light sources 200 formed in each of the first light source substrate 201, the second light source substrate 202, and the third light source substrate 203 by the first correction amount. For example, the light emission timings of the plurality of light sources 200 formed on the first light source substrate 201 are corrected with the first correction amount determined for the first light source substrate 20 .

FIG. 21 is a block diagram showing an example of functions of CPU 111 included in MFP 100 in the second modification. 21, the function differs from that shown in FIG. 11 in that correction unit 55 and exposure control unit 57 are changed to correction unit 55B and exposure control unit 57A. The correction unit 55A determines the first correction amount for each of the first light source substrate 201, the second light source substrate 202, and the third light source substrate 203, and outputs the first correction amount to the exposure control unit 57A.

The exposure controller 57A controls the exposure devices 21Y, 21M, 21C, and 21K based on the first correction amount for each of the first light source substrate 201, the second light source substrate 202, and the third light source substrate 203 input from the correction unit 55B. The timing for emitting light from the plurality of light sources 200 included respectively is corrected. Specifically, the exposure control unit 57A corrects the light emission timings of the plurality of light sources 200 formed on the second light source substrate 202 with the first correction amount determined for the second light source substrate 202, The light emission timings of the plurality of light sources 200 formed on the light source substrate 203 are corrected by the first correction amount determined for the third light source substrate 203 . If the correction amount is positive, the light emission timing is delayed by the correction amount, and if the correction amount is negative, the light emission timing is advanced by the correction amount. Since the first correction amount determined for the first light source substrate 201 is zero, the light emission timings of the plurality of light sources 200 formed on the first light source substrate 201 are not corrected.

FIG. 22 is a block diagram showing an example of detailed functions of a correction unit in the second modified example. 22, correction unit 55B in the second modification differs from correction unit 55 shown in FIG. 12 in that irradiation distance calculation unit 63 and correction amount determination unit 65 81 and the first correction amount determination unit 83 are changed. Since other functions are the same as those shown in FIG. 12, the description will not be repeated here.

The board distance calculator 81 calculates the board distance corresponding to the first light source board 201 , the board distance corresponding to the second light source board 202 , and the board distance corresponding to the third light source board 203 . The substrate distance is the distance in the sub-scanning direction between the reference substrate position of the reference substrate and the reference substrate position of the reference substrate. The reference substrate position is the irradiation position of the representative light source on the reference substrate. The representative light source of the reference substrate is the representative light source of the representative group among the plurality of light source groups included in the reference substrate. The reference substrate position is the irradiation position of the representative light source on the reference substrate. The representative light source of the reference substrate is the representative light source of the representative group among the plurality of light source groups included in the reference substrate. Here, a case where the first light source substrate 201 is set as the reference substrate and the second light source substrate 202 and the third light source substrate 203 are set as the reference substrate will be described as an example.

For each of the first light source substrate 201, the second light source substrate 202, and the third light source substrate 203, one of the plurality of light sources 200 formed on that substrate is determined as the representative light source of that substrate. The plurality of light source groups included in each of the first light source substrate 201, the second light source substrate 202, and the third light source substrate 203 include representative groups and reference groups other than the representative groups. Here, for the first light source board 201, the light source group 212 is the representative group, and the light source 200 No. 14 belonging to the light source group 212 is the representative light source. Therefore, the fourteenth light source 200 is the representative light source of the first light source substrate 201 . The second light source board 202 uses the light source group 222 as a representative group, and the fifth light source 200 belonging to the light source group 222 as a representative light source. Therefore, the fifth light source 200 is the representative light source of the second light source substrate 202 . Further, the third light source board 203 has the light source group 232 as a representative group, and the light source 200 No. 23 belonging to the light source group 232 as a representative light source. Therefore, the 23rd light source 200 is the representative light source of the third light source substrate 203 .

Therefore, since the reference substrate is the first light source substrate 201 , the reference substrate position is the irradiation position of the representative light source of the first light source substrate 201 . The board distance calculator 81 determines the board distance of the first light source board 201 to be zero. The substrate distance calculator 81 determines the distance in the sub-scanning direction between the reference substrate position, which is the irradiation position of the representative light source of the reference substrate, and the reference substrate position, which is the irradiation position of the representative light source of the reference substrate, as the substrate distance of the reference substrate. . When the reference substrate position is positioned upstream in the sub-scanning direction from the reference substrate position, the substrate distance of the reference substrate is set to a positive value, and the reference substrate position is positioned downstream in the sub-scanning direction from the reference substrate position. , the substrate distance of the reference substrate is taken as a negative value. Specifically, the board distance calculation unit 81 determines the distance between the reference board position and the reference board position of the second light source board 202 as the board distance of the second light source board 202 and the reference board distance of the third light source board 203 . The distance between the substrate position and the reference substrate position is determined as the substrate distance of the second light source substrate 202 .

The substrate distance calculator 81 outputs the substrate distance of the first light source substrate 201 , the substrate distance of the second light source substrate 202 and the substrate distance of the third light source substrate 203 to the first correction amount determination unit 83 .

The first correction amount determination unit 83 determines the first correction amount corresponding to the second light source substrate 202 based on the substrate distance of the second light source substrate 202 . Specifically, the first correction amount determination unit 83 determines a value obtained by dividing the board distance of the second light source board 202 by the image forming speed as the first correction amount. The first correction amount determination unit 83 determines the first correction amount corresponding to the third light source substrate 203 based on the substrate distance of the third light source substrate 203 . Specifically, the first correction amount determination unit 83 determines a value obtained by dividing the substrate distance corresponding to the third light source substrate 203 by the image forming speed as the first correction amount.

FIG. 23 is a block diagram showing an example of detailed functions of the substrate distance calculator. Referring to FIG. 23, board distance calculator 81 includes a board representative group determiner 82, a board reference group position determiner 67B, and a board reference group position determiner 69B. The board representative group determination unit 82 determines board representative groups for each of the first light source board 201 , the second light source board 202 and the third light source board 203 . The board representative group is a light source group representing each of the first light source board 201, the second light source board 202, and the third light source board 203. FIG. Here, among the plurality of light source groups included in the light source substrate, the light source group arranged at the center in the sub-scanning direction is determined as the substrate light source group representing the light source substrate. Specifically, the board representative group determining unit 82 determines the light source group 212 in the fifth column included in the first light source board 201 as the board representative group, and the light source group in the second column included in the second light source board 202 as the board representative group. 222 is determined as the board representative group, and the light source group 232 in the eighth column included in the third light source board 203 is determined as the board representative group.

The board reference group position determination unit 67B sets one of the plurality of light source groups as the board reference group. The board reference group position determination unit 67B connects the plurality of light sources 200 belonging to each of the board representative groups of the first light source board 201, the second light source board 202, and the third light source board 203 to the rotation center of the photosensitive drum 23Y. A substrate representative group in which the angle at which the dashed line intersects the surface of the photosensitive drum 23Y is perpendicular or most perpendicular is determined as the substrate reference group. Here, the board reference group position determination unit 67B determines the light source group 212 in the fifth column, which is the board representative group of the first light source board 201, as the board reference group. The representative light source of the light source group 212, which is the substrate reference group, is the 14th light source 200. FIG.

The board reference group position determination unit 67B determines the irradiation position of the light source group 212 in the fifth column, which is the board reference group, among the irradiation positions of the plurality of light source groups input from the group position acquisition unit 61, to the first light source board 201. to the irradiation position. The irradiation position of the first light source substrate 201 is the reference substrate position.

The board reference group position determining unit 69B determines a board representative group other than the board reference group among the plurality of board representative groups as a board reference group. Here, the light source group 222 in the second column, which is the board representative group of the second light source board 202, and the light source group 232 in the eighth column, which is the board representative group of the third light source board 203, are determined as board reference groups. . The board reference group position determination unit 69B determines the irradiation positions of the light source groups 222 in the second row, which are the board reference groups, among the irradiation positions of the plurality of light source groups input from the group position acquisition unit 61, to the second light source board 202. to the irradiation position. The irradiation position of the second light source substrate 202 is the reference substrate position. Similarly, the board reference group position determination unit 69B determines the irradiation position of the light source group 232 in the eighth column, which is the board reference group, to be the irradiation position of the third light source board 203 . The irradiation position of the third light source substrate 203 is the reference substrate position.

FIG. 24 is a flowchart showing an example of the flow of light emission timing correction processing in the third modified example. Referring to FIG. 24, CPU 111 causes image forming unit 140 to form an image of test data (step S31). In the next step S32, irradiation position data is acquired. Steps S31 and S32 are the same as steps S01 and S02 in FIG. Therefore, the detailed description will not be repeated here.

In step S33, a first correction amount determination process is executed, and the process proceeds to step S34. The details of the first correction amount determination process will be described later, but this is a process of determining the first correction amount for each of the first light source substrate 201 , the second light source substrate 202 and the third light source substrate 203 .

In the next step S34, a substrate to be processed is selected from among the first light source substrate 201, the second light source substrate 202 and the third light source substrate 203, and the process proceeds to step S35. In step S35, one of the plurality of light source groups included in the substrate selected as the processing target is selected as the processing target, and the process proceeds to step S36. In step S36, the light emission timings of the plurality of light sources 200 belonging to the light source group selected for processing are corrected using the first correction amount for the substrate selected in step S34, and the process proceeds to step S37. In step S37, it is determined whether or not there is a light source group that has not been selected as a processing target. If there is an unselected light source group, the process returns to step S35; otherwise, the process proceeds to step S38.

In step S38, it is determined whether or not there is a substrate among the first light source substrate 201, the second light source substrate 202, and the third light source substrate 203 that has not been selected as a processing target in step S34. If there is an unselected substrate, the process returns to step S34; otherwise, the process ends. Thereby, step S36 is executed for all of the plurality of light source groups included in the second light source substrate 202 and the third light source substrate 203, respectively. Since the first correction amount of the first light source substrate 201, which is the reference substrate, is zero, the light emission timings of the plurality of light sources 200 belonging to the light source groups 211, 212, and 213 are not corrected.

FIG. 25 is a flow chart showing an example of the flow of the first correction amount determination process. The first correction amount determination process is a process executed in step S33 of FIG. Referring to FIG. 25, CPU 111 determines a board representative group of the reference board (step S41). Here, among the plurality of light source groups, a light source group 212 in which a line connecting a plurality of light sources 200 belonging thereto and the center of rotation of the photosensitive drum 23Y intersects the surface of the photosensitive drum 23Y at a vertical angle or the most perpendicular angle is a light source group 212. is determined as the board representative group of the reference board.

In the next step S42, the reference board position is determined. The reference substrate position is the irradiation position of the reference substrate. The reference board is the first light source board 201 which includes a light source group 212 which is a board reference group. Among the irradiation positions of the plurality of light source groups determined by the irradiation position data, the irradiation position of the light source group 212 in the fifth column, which is the board representative group of the reference board, is determined as the reference board position.

In the next step S43, a reference substrate is selected. Among the first light source substrate 201, the second light source substrate 202 and the third light source substrate 203, the second light source substrate 202 and the third light source substrate 203 other than the reference substrate are reference substrates. One of the second light source substrate 202 and the third light source substrate 203 to be processed is selected. Here, an example in which the second light source substrate 202 is selected as an object to be processed will be described.

In step S44, a board representative group of the reference board selected as the processing target is determined. Here, the light source group 222 in the second column included in the second light source board 202 selected as the processing target is determined as the board representative group. Among the light source groups 221, 222, and 223 included in the second light source substrate 202, the light source group 222 arranged at the center in the sub-scanning direction is determined as the substrate representative group.

In the next step S45, the reference substrate position is detected. The reference substrate position is the irradiation position of the reference substrate. Among the irradiation positions of the plurality of light source groups determined by the irradiation position data, the irradiation position of the light source group 222 in the second row determined as the board representative group of the reference board in step S44 is determined as the reference board position.

In the next step S46, the substrate distance is calculated, and the process proceeds to step S47. The substrate distance is the distance in the sub-scanning direction between the irradiation position on the reference substrate and the irradiation position on the reference substrate. Here, the distance between the irradiation position of the first light source substrate 201 which is the reference substrate and the irradiation position of the second light source substrate 202 which is the reference substrate is calculated as the substrate distance of the second light source substrate 202 which is the reference substrate. do.

In the next step S47, the first correction amount for the reference substrate is determined, and the process proceeds to step S48. A value obtained by dividing the substrate distance of the reference substrate calculated in step S46 by the image forming speed is determined as the first correction amount. In step S48, it is determined whether or not there is a reference substrate that has not been selected as a processing target in step S43. If there is an unselected reference substrate, the process returns to step S43; otherwise, the process returns to the light emission timing correction process. Steps S43 to S47 are executed for each of the second light source substrate 202 and the third light source substrate 203, which are reference substrates, to determine the first correction amount for each.

An exposure apparatus 21Y in the third modification includes a first light source substrate 201 formed with a plurality of light sources 200 belonging to light source groups 211, 212, and 213, and a plurality of light sources 200 belonging to light source groups 221, 222, and 223, respectively. a second light source substrate 202 and a third light source substrate 203 formed with a plurality of light sources 200 belonging to light source groups 231, 232, and 233 respectively; includes board representative groups 212, 222, and 223, respectively, and each of the plurality of light source groups 211, 212, 213, 221, 222, 223, 231, 232, and 233 is selected from among the plurality of light sources 200 belonging thereto. The CPU 111 determines the first light source substrate 201 and the second light source based on the substrate distances in the sub-scanning direction between the three irradiation positions of the plurality of representative light sources belonging to the substrate representative groups 212, 222, and 223, respectively. A first correction amount for correcting the light emission timing of the plurality of light sources 200 formed on the substrate is determined for each of the substrate 202 and the third light source substrate 203 . Therefore, since it is sufficient to detect the irradiation positions for each of the board representative groups 212, 222, and 223, irradiation positions corresponding to all of the plurality of light source groups 211, 212, 213, 221, 222, 223, 231, 232, and 233 can be detected. There is no need to detect , the processing is simplified, and the correction amount can be easily determined.

<Fourth Modification>
MFP 100 in the third modification determines the first correction amount for each of first light source substrate 201 , second light source substrate 202 and third light source substrate 203 . In addition to determining the first correction amount for each of the first light source substrate 201, the second light source substrate 202, and the third light source substrate 203, the MFP 100 in the fourth modified example 202 and the third light source substrate 203 are determined for the second correction amount.

FIG. 26 is a block diagram showing an example of detailed functions of a correction unit in the fourth modification. Referring to FIG. 26, correction unit 55C has irradiation distance calculation unit 63B and second correction amount determination unit 85 added in addition to the functions shown in FIG. Other functions are the same, so the description will not be repeated here.

The irradiation distance calculation unit 63B determines a reference group for each of the first light source substrate 201, the second light source substrate 202, and the third light source substrate 203, and performs irradiation of the light source group based on the irradiation position of the light source group and the irradiation position of the reference group. Determine position. Here, the second light source substrate 202 will be described as an example. The irradiation distance calculator 63B sets the light source group 222, which is the representative group of the second light source substrate 202, as the reference group. Then, the light source groups 221 and 223 other than the representative group are set as reference groups. The irradiation distance calculator 63B determines the irradiation distance of the light source group 222 as the distance in the sub-scanning direction between the irradiation position of the light source group 221 as the reference group and the irradiation position of the light source group 222 as the reference group. Similarly, the irradiation distance calculator 63B determines the distance in the sub-scanning direction between the irradiation position of the light source group 223, which is the reference group, and the irradiation position of the light source group 222, which is the reference group, as the irradiation distance of the light source group 223. . The irradiation distance calculator 63 B outputs the irradiation distances of the light source groups 222 and 223 to the second correction amount determination unit 85 . Note that the irradiation distance of the light source group 222, which is the reference group, is zero.

A second correction amount determination unit 85 determines a second correction amount based on the irradiation distances of the light source groups 221 and 223 . Specifically, a value obtained by dividing the irradiation distance of the light source group 221 by the image forming speed is determined as the second correction amount of the light source group 221 . Also, a value obtained by dividing the irradiation distance of the light source group 223 by the image forming speed is determined as the second correction amount of the light source group 223 . Since the irradiation distance of the light source group 222, which is the reference group, is zero, the second correction amount of the light source group 222 is determined to be zero.

55 C of correction|amendment parts determine correction amount from a 1st correction amount and a 2nd correction amount for every several light source group. A value obtained by adding the first correction amount and the second correction amount may be used as the correction amount.

FIG. 27 is a flowchart showing an example of the flow of light emission timing correction processing in the fourth modification. Referring to FIG. 27, steps S31 to S33 are the same as steps S31 to S33 shown in FIG. In step S33, a first correction amount determination process is executed, and the process proceeds to step S51.

In step S51, a substrate to be processed is selected from among the first light source substrate 201, the second light source substrate 202 and the third light source substrate 203, and the process proceeds to step S52. In step S52, a second correction amount determination process is executed, and the process proceeds to step S53. The details of the second correction amount determination process will be described later, but this is a process of determining the second correction amount for each of the plurality of light source groups included in each substrate selected as a processing target.

In step S53, it is determined whether or not there is a substrate among the first light source substrate 201, the second light source substrate 202, and the third light source substrate 203 that has not been selected as a processing target in step S51. If there is an unselected substrate, the process returns to step S51; otherwise, the process proceeds to step S54.

In step S54, one of the plurality of light source groups included in the substrate selected as the processing target is selected as the processing target, and the process proceeds to step S55. In step S55, the light emission timings of the plurality of light sources 200 belonging to the light source group selected for processing are corrected using the first correction amount and the second correction amount, and the process proceeds to step S56. In step S56, it is determined whether or not there is a light source group that has not been selected as a processing target. If there is an unselected light source group, the process returns to step S54; otherwise, the process ends. Accordingly, by executing step S38 for all of the plurality of light source groups, correction amounts for each of the plurality of light source groups 211, 212, 213, 221, 222, 223, 231, 232, and 233 are determined. The light emission timing of the light source 200 is corrected. However, since the amount of correction for the light source group 212 in the fifth column, which is the representative group of the first light source board 201, which is the reference board, is not determined, the light emission timings of the plurality of light sources 200 belonging to the light source group 212 are not corrected.

FIG. 28 is a flowchart illustrating an example of the flow of second correction amount determination processing. The second correction amount determination process is a process executed in step S52 of FIG. In step S51 before the second correction amount determination process is executed, the substrate is selected as the processing target. Here, a case where the second light source substrate 202 is selected will be described as an example.

Referring to FIG. 28, CPU 111 sets a representative group of second light source substrate 202 selected as a processing target as a reference group (step S61). A representative group of the second light source substrate 202 is the light source group 222 . In the next step S62, the irradiation position of the reference group is determined, and the process proceeds to step S63. Among the irradiation positions of the plurality of light source groups determined by the irradiation position data, the irradiation position of the light source group 222 in the second row determined as the reference group in step S61 is determined as the reference group position.

In step S63, one of the light source groups 221, 222, and 223 included in the second light source board 202 selected as the processing target is selected as the processing target, and the process proceeds to step S64. In step S64, it is determined whether or not the light source group selected as the processing target is the reference group. If it is the reference group, the process proceeds to step S68; otherwise, the process proceeds to step S65. In step S65, the irradiation position of the light source group selected as the processing target is determined, and the process proceeds to step S67. The irradiation position of the light source group is the irradiation position corresponding to the representative light source of the light source group. For example, when the light source group 221 is selected as the processing target, the irradiation position of the fourth light source 200, which is the representative light source of the light source group 221, is determined as the irradiation position of the light source group.

In step S66, the irradiation distance of the light source group selected as the processing target is calculated. The distance in the sub-scanning direction between the irradiation position of the light source group and the irradiation position of the reference group is calculated as the irradiation distance of the light source group. The irradiation distance is calculated from the irradiation position of the light source group determined in step S65 and the irradiation position of the reference group determined in step S62. The irradiation distance becomes a positive value when the irradiation position of the light source group is positioned upstream in the sub-scanning direction from the irradiation position of the reference group, and the irradiation position of the light source group is further in the sub-scanning direction than the irradiation position of the reference group. If it is located on the downstream side, it will have a negative value.

In the next step S67, the second correction amount for the light source group selected as the processing target is determined, and the process proceeds to step S68. A value obtained by dividing the irradiation distance calculated in step S66 by the image forming speed is determined as the second correction amount.

In step S68, it is determined whether or not there is a light source group that has not been selected as a processing target in step S62. If there is an unselected light source group, the process returns to step S63; otherwise, the process returns to the light emission timing correction process.

In the exposure apparatus 21Y in the fourth modification, in each of the first light source substrate 201, the second light source substrate 202, and the third light source substrate 203, for example, the light source groups 211, 212, and 213 included in the first light source substrate 201 are , a reference group 212, and reference groups 211 and 213, and the CPU 111 performs, for each of the first light source substrate 201, the second light source substrate 202, and the third light source substrate 203, the reference group included in the first light source substrate 201, for example. The reference group position detected as the irradiation position corresponding to the representative light source belonging to the groups 211 and 213 and the reference group position detected as the irradiation position corresponding to the representative light source belonging to the reference group 212 included in the first light source board 201. A second correction amount for correcting the light emission timings of the plurality of light sources 200 belonging to the reference groups 211 and 213 is determined based on the irradiation distance in the sub-scanning direction between them. Therefore, for each of the first light source substrate 201, the second light source substrate 202, and the third light source substrate 203, for example, the second correction amounts of the light source groups 211, 212, and 213 of the first light source substrate 201 are determined. , the amount of correction can be determined accurately.

<Second Embodiment>
The MFP 100 according to the second embodiment is provided with two first registration sensors 39A and a second registration sensor 39B at different positions in the main scanning direction between the image forming unit 20K and the transfer roller 26. be.

FIG. 29 is a bottom view of the intermediate transfer belt in the second embodiment. The first registration sensor 39A and the second registration sensor 39B are arranged at both ends of the intermediate transfer belt 30 in the main scanning direction. Therefore, the first registration sensor 39A can read the toner image formed on the intermediate transfer belt 30 within the first range in the main scanning direction. Of the toner image formed on the belt 30, the toner image can be read in the area within the second range in the main scanning direction. Here, the first registration sensor 39A is arranged at a position where the toner image formed at the irradiation positions corresponding to the first to twenty-seventh light sources 200 included in the first range can be read. The second registration sensor 39B is arranged at a position where the toner image formed at the irradiation positions corresponding to the (N−26)th to Nth light sources 200 included in the second range can be read. However, N is the number of multiple light sources formed in each of the first light source substrate 201, the second light source substrate 202, and the third light source substrate 203, and is a positive integer of 54 or more.

FIG. 30 is a block diagram showing an example of functions of a CPU included in the MFP according to the second embodiment. The functions shown in FIG. 30 are formed in CPU 111 of MFP 100 by executing the light emission timing correction program. The difference from the functions shown in FIG. 11 is that the sensor control section 51, the detection section 53 and the correction section 55 are changed to the first sensor control section 51A, the first detection section 53A and the correction section 55D, respectively, and the second sensor control. The point is that the unit 51B and the second detection unit 53B are added. Since other functions are the same as those shown in FIG. 11, the description will not be repeated here.

In each of the first detection unit 53A and the second detection unit 53B, light emitted from a plurality of light sources 200 included in each of the exposure devices 21Y, 21M, 21C, and 21K is irradiated onto the photosensitive drums 23Y, 23M, 23C, and 23K. Detects the irradiation position. Specifically, the first detection unit 53A outputs test data to the exposure control unit 57, and causes the exposure devices 21Y, 21M, 21C, and 21K to irradiate light according to the test data. The test data is image data corresponding to each of the four colors of yellow, cyan, magenta, and black. The test data preferably contains images of straight lines parallel to the main scanning direction.

Since the first detection unit 53A and the second detection unit 53B detect the irradiation positions corresponding to the exposure devices 21Y, 21M, 21C, and 21K in the same manner, the exposure device 21Y will be described as an example. Yellow test data is input to the exposure device 21Y.

The first detection unit 53A outputs a reading instruction to the first sensor control unit 51A to cause the toner image formed on the intermediate transfer belt 30 to be read. The first sensor control unit 51A controls the registration sensor 39A to read the toner image in the first range formed on the intermediate transfer belt 30, and acquires the first read data output by the registration sensor 39A. The first sensor control section 51A outputs the acquired first read data to the detection section 53 .

Based on the first read data input from the first sensor control unit 51A, the first detection unit 53A detects light emitted from each of the plurality of light sources 200 included in the exposure device 21Y. Detect location. The irradiation position is expressed in a coordinate space whose coordinate axes are the main scanning direction and the sub-scanning direction.

The images of straight lines parallel to the main scanning direction included in the yellow test data are at least the 1st to 27th light sources in the first range and the 1st ( (N-26) includes images corresponding to the light sources 200 numbered N-26). Therefore, the first detection unit 53A uses the first read data output from the first registration sensor 39A to determine whether the light emitted from each of the light sources 200 Nos. 1 to 27 of the exposure device 21Y is detected by the photoreceptor drum 23Y. Detects the irradiated position. The first detection unit 53A corrects first irradiation position data indicating the first to twenty-seventh irradiation positions detected corresponding to the first to twenty-seventh light sources 200 included in the exposure device 21Y. 55D. In the first read data, the brightness of the pixels on which the toner image is formed is lower than the brightness of the pixels on which the toner image is not formed. On the other hand, positions in the main scanning direction are determined in advance at irradiation positions corresponding to the first to twenty-seventh light sources 200 within the first range. For this reason, the first detection unit 53A specifies the irradiation positions corresponding to the light sources 200 No. 1 to No. 27 as the positions of the pixel values at which the lightness is low and which exist at predetermined positions in the main scanning direction. do.

The second detection unit 53B outputs a reading instruction to the second sensor control unit 51B to read the toner image formed on the intermediate transfer belt 30 within the second range. The second sensor control section 51B controls the second registration sensor 39B to read the toner image within the second range formed on the intermediate transfer belt 30, and obtains the second read data output by the second registration sensor 39B. do. The second sensor control section 51B outputs the acquired second read data to the detection section 53 .

Based on the second read data input from the second sensor control unit 51B, the second detection unit 53 detects light emitted from each of the plurality of light sources 200 included in the exposure device 21Y. Detect location.

The second detection unit 53B uses the second read data output from the second registration sensor 39B to determine whether the (N−26)th to Nth light sources 200 included in the second range of the exposure device 21Y are emitted. The irradiation position where the light is irradiated onto the photosensitive drum 23Y is detected. The second detection unit 53B indicates the (N-26)-th to N-th irradiation positions detected corresponding to the (N-26)-th to N-th light sources 200 included in the exposure device 21Y. The second irradiation position data is output to the correction section 55D. The second detection unit 53B regards the irradiation positions corresponding to the (N−26)th to Nth light sources 200 as the positions of the pixel values at which the lightness is low and which exist at predetermined positions in the main scanning direction. Identify.

Ideally, the irradiation positions at which the light emitted from the first to twenty-seventh light sources and the (N-26)th to Nth light sources 200 of the exposure device 21Y are irradiated onto the photosensitive drum 23Y. It becomes a straight line parallel to the main scanning direction on the body drum 23Y. Therefore, the 1st to 27th irradiation positions and the (N−26)th to Nth irradiation positions indicated by the irradiation position data should be at the same position in the sub-scanning direction. However, the relative positions of the first light source substrate 201, the second light source substrate 202 and the third light source substrate 203 are shifted, and the relative positions of the first light source substrate 201, the second light source substrate 202 and the third light source substrate 203 and the photosensitive drum 23Y. Due to a positional deviation or the like, the 1st to 27th irradiation positions and the (N−26)th to Nth irradiation positions may not be the same in the sub-scanning direction.

The correction unit 55D calculates the first irradiation distance in the sub-scanning direction between at least two of the plurality of irradiation positions indicated by the first irradiation position data input from the first detection unit 53A and the first irradiation distance input from the second detection unit 53B. and a second irradiation distance in the sub-scanning direction between at least two of the plurality of irradiation positions indicated by the second irradiation position data. Determines the amount of correction for

Specifically, the correction unit 55D determines the first correction amount for each of the first light source substrate 201, the second light source substrate 202 and the third light source substrate 203, and the correction unit 55D determines the first light source substrate 201, the second light source substrate A correction amount for determining the second correction amount for each of the light source substrate 202 and the third light source substrate 203, and correcting the light emission timings of the plurality of light sources 200 included in the exposure device 21Y from the first correction amount and the second correction amount. to decide. The correction section 55D outputs the correction amount of each of the plurality of light sources 200 to the exposure control section 57. FIG.

The exposure control section 57 corrects the timing of light emission of the plurality of light sources 200 included in the exposure devices 21Y, 21M, 21C, and 21K based on the correction amount for each of the plurality of light sources 200 input from the correction section 55D. For example, the exposure control unit 57 corrects the light emission timings of the plurality of light sources 200 belonging to the light source group 211 using the correction amount. If the correction amount is positive, the light emission timing is delayed by the correction amount, and if the correction amount is negative, the light emission timing is advanced by the correction amount.

31 is a diagram illustrating an example of detailed functions of a correction unit according to the second embodiment; FIG. The correction unit 55D includes a first group position acquisition unit 61A, a second group position acquisition unit 61B, a first substrate distance calculation unit 81A, a second substrate distance calculation unit 81B, a first correction amount determination unit 83A, It includes an irradiation distance calculator 63C and a second correction amount determiner 85A.

The first group position acquisition unit 61A acquires irradiation positions in the first range corresponding to each of the plurality of light source groups. The first group position acquisition unit 61A determines, for each of the plurality of light source groups, one of the plurality of light sources 200 included in the light source group in the first range as the first representative light source. Here, since the first irradiation position data includes irradiation positions corresponding to the first to twenty-seventh light sources 200 in the first range, any one of the three light sources 200 included in the target light source group is selected as the first irradiation position data. 1 representative light source. For example, the group position acquisition unit 61 selects the sub-main scanning light source 200 of the three light sources 200, 10th, 13th, and 16th, included in the first lens group 241A among the plurality of light sources included in the light source group 211. The thirteenth light source 200 located at the center in the direction is determined as the first representative light source of the light source group 211 . Similarly, the first group position acquisition unit 61A determines the 14th light source 200 included in the light source group 212 as the first representative light source of the light source group 212 . Similarly, the first group position acquisition unit 61A determines the 15th light source 200 included in the light source group 213 as the first representative light source of the light source group 213 .

Similarly, for the second light source board 202, the first group position acquisition unit 61A determines the fourth light source 200 included in the light source group 221 as the first representative light source of the light source group 221, and The fifth light source 200 is determined as the first representative light source of the light source group 222 , and the sixth light source 200 included in the light source group 223 is determined as the first representative light source of the light source group 223 . Similarly, for the third light source board 203, the first group position acquisition unit 61A determines the light source 200 No. 22 included in the light source group 231 as the first representative light source of the light source group 231, and The 23rd light source 200 is determined as the first representative light source of the light source group 232 , and the 24th light source 200 included in the light source group 233 is determined as the first representative light source of the light source group 233 .

The first group position acquisition unit 61A outputs the irradiation position corresponding to the first representative light source of the light source group to the first substrate distance calculation unit 81A and the irradiation distance calculation unit 63C for each of the plurality of light source groups. Hereinafter, the irradiation position corresponding to the first representative light source of the light source group will be referred to as the first irradiation position of the light source group.

The second group position acquisition unit 61B acquires irradiation positions in the second range corresponding to each of the plurality of light source groups. The second group position acquisition unit 61B determines, for each of the plurality of light source groups, one of the plurality of light sources 200 included in the light source group in the second range as the second representative light source. Here, since the second irradiation position data includes the irradiation positions corresponding to the (N−26)th to Nth light sources 200 in the second range, the three light sources 200 included in the target light source group Either one is determined as the second representative light source. For example, the second group position acquisition unit 61B obtains the (N−17)th, (N−14)th, and (N−1)th light sources included in the first lens group 241A among the plurality of light sources included in the light source group 211. 11) Of the three numbered light sources 200, the (N-14)th light source 200 located at the center in the sub-main scanning direction is determined as the second representative light source of the light source group 211. FIG. Similarly, the second group position acquisition unit 61B determines the (N−13)th light source 200 included in the light source group 212 as the second representative light source of the light source group 212 . Similarly, the second group position acquisition unit 61B determines the (N−12)th light source 200 included in the light source group 213 as the second representative light source of the light source group 213 .

Similarly, for the second light source board 202, the second group position acquisition unit 61B determines the (N-23)th light source 200 included in the light source group 221 as the second representative light source of the light source group 221, and 222 is determined as the second representative light source of the light source group 221, and the (N-21)th light source 200 included in the light source group 223 is determined as the second representative light source of the light source group 223. Determine the representative light source. Similarly, for the third light source substrate 203, the second group position acquisition unit 61B determines the (N-5)th light source 200 included in the light source group 231 as the second representative light source of the light source group 231, 232 is determined as the second representative light source of the light source group 232, and the (N-3)th light source 200 included in the light source group 233 is determined as the second representative light source of the light source group 233. Determine the representative light source.

The second group position acquisition section 61B outputs the irradiation position corresponding to the second representative light source of the light source group to the second substrate distance calculation section 81B for each of the plurality of light source groups. Hereinafter, the irradiation position corresponding to the second representative light source of the light source group will be referred to as the second irradiation position of the light source group.

The first board distance calculator 81A has the same function as the board distance calculator 81 shown in FIG. Specifically, the first substrate distance calculator 81A calculates the first substrate distance corresponding to the first light source substrate 201, the first substrate distance corresponding to the second light source substrate 202, and the first substrate distance corresponding to the third light source substrate 203. Calculate the substrate distance. The first substrate distance is the distance in the sub-scanning direction between the first reference substrate position of the reference substrate and the first reference substrate position of the reference substrate. The first reference substrate position is the irradiation position of the first substrate representative light source on the reference substrate. The first substrate representative light source of the reference substrate is the first representative light source of the representative group among the plurality of light source groups included in the reference substrate. The first reference substrate position is the irradiation position of the first substrate representative light source on the reference substrate. The first substrate representative light source of the reference substrate is the first representative light source of the representative group among the plurality of light source groups included in the reference substrate. Here, a case where the first light source substrate 201 is set as the reference substrate and the second light source substrate 202 and the third light source substrate 203 are set as the reference substrate will be described as an example.

For each of the first light source substrate 201, the second light source substrate 202, and the third light source substrate 203, one of the plurality of light sources 200 formed on that substrate is determined as the first substrate representative light source of that substrate. Here, the first substrate representative light source of the first light source substrate 201 is the 14th light source 200, the first substrate representative light source of the second light source substrate 202 is the fifth light source 200, and the third light source substrate. The first substrate representative light source 203 is the 23rd light source 200 .

Therefore, since the reference substrate is the first light source substrate 201 , the first reference substrate position is the irradiation position of the first substrate representative light source of the first light source substrate 201 . The first substrate distance calculator 81A determines the first substrate distance of the first light source substrate 201 to be zero. The first substrate distance calculator 81A performs sub-scanning between a first reference substrate position, which is the irradiation position of the first substrate representative light source of the reference substrate, and a first reference substrate position, which is the irradiation position of the first substrate representative light source of the reference substrate. A direction distance is determined to be the first substrate distance of the reference substrate. When the first reference substrate position is located upstream of the first reference substrate position in the sub-scanning direction, the first substrate distance of the reference substrate is set to a positive value, and the first reference substrate position is greater than the first reference substrate position. When positioned downstream in the sub-scanning direction, the first substrate distance of the reference substrate is set to a negative value. Specifically, the first substrate distance calculator 81A determines the distance between the first reference substrate position and the first reference substrate position of the second light source substrate 202 as the first substrate distance of the second light source substrate 202. , the distance between the first reference substrate position of the third light source substrate 203 and the first reference substrate position is determined as the first substrate distance of the second light source substrate 202 .

The first substrate distance calculation unit 81A calculates the first substrate distance of the first light source substrate 201, the first substrate distance of the second light source substrate 202, and the first substrate distance of the third light source substrate 203 by the first correction amount determination unit 83A. output to

The second board distance calculator 81B has the same function as the board distance calculator 81 shown in FIG. Specifically, the second substrate distance calculator 81B calculates the second substrate distance corresponding to the first light source substrate 201, the second substrate distance corresponding to the second light source substrate 202, and the second substrate distance corresponding to the third light source substrate 203. Calculate the board distance. The second substrate distance is the distance in the sub-scanning direction between the second reference substrate position of the reference substrate and the second reference substrate position of the reference substrate. The second reference substrate position is the irradiation position of the second substrate representative light source on the reference substrate. The second substrate representative light source of the reference substrate is the second representative light source of the representative group among the plurality of light source groups included in the reference substrate. The second reference substrate position is the irradiation position of the second substrate representative light source on the reference substrate. The second substrate representative light source of the reference substrate is the second representative light source of the representative group among the plurality of light source groups included in the reference substrate. Here, a case where the first light source substrate 201 is set as the reference substrate and the second light source substrate 202 and the third light source substrate 203 are set as the reference substrate will be described as an example.

For each of the first light source substrate 201, the second light source substrate 202, and the third light source substrate 203, one of the plurality of light sources 200 formed on that substrate is determined as the second substrate representative light source of that substrate. Here, the second substrate representative light source of the first light source substrate 201 is the (N-13)th light source 200, and the second substrate representative light source of the second light source substrate 202 is the (N-22)th light source. 200 , and the second substrate representative light source of the third light source substrate 203 is the (N−4)th light source 200 .

Therefore, since the reference substrate is the first light source substrate 201 , the second reference substrate position is the irradiation position of the second substrate representative light source of the first light source substrate 201 . The second substrate distance calculator 81B determines the second substrate distance of the first light source substrate 201 to be zero. The second substrate distance calculator 81B performs sub-scanning between a second reference substrate position, which is the irradiation position of the second substrate representative light source of the reference substrate, and a second reference substrate position, which is the irradiation position of the second substrate representative light source of the reference substrate. The direction distance is determined to be the second substrate distance of the reference substrate. When the second reference substrate position is located upstream of the second reference substrate position in the sub-scanning direction, the second substrate distance of the reference substrate is set to a positive value, and the second reference substrate position is greater than the second reference substrate position. When positioned downstream in the sub-scanning direction, the second substrate distance of the reference substrate is set to a negative value. Specifically, the second substrate distance calculator 81B determines the distance between the second reference substrate position and the second reference substrate position of the second light source substrate 202 as the second substrate distance of the second light source substrate 202. , the distance between the second reference substrate position and the second reference substrate position of the third light source substrate 203 is determined as the second substrate distance of the second light source substrate 202 .

The second substrate distance calculation unit 81B calculates the second substrate distance of the first light source substrate 201, the second substrate distance of the second light source substrate 202, and the second substrate distance of the third light source substrate 203 by the first correction amount determination unit 83A. output to

The first correction amount determination unit 83A determines the first correction amount corresponding to the reference substrate based on the first substrate distance and the second substrate distance corresponding to the reference substrate. The first correction amount is a value obtained by dividing the first substrate distance corresponding to the reference substrate by the image forming speed when the first substrate distance and the second substrate distance are the same. When the first substrate distance and the second substrate distance are different, the reference substrate and the standard substrate are not parallel in the main scanning direction and are inclined. Therefore, the first correction amount determining unit 83A determines the first substrate distance and the second substrate distance for each of the plurality of light sources 200 belonging to the representative group of the reference substrate as the light source 200 and the first substrate representative light source. and a second placement distance between the light source 200 and the second substrate representative light source to determine the substrate distance for the light source. Specifically, the first correction amount determination unit 83A determines the first substrate distance and the second substrate distance for each of the plurality of light sources 200 belonging to the representative group of the reference substrate as the first arrangement distance and the second arrangement distance, respectively. is determined as the substrate distance, and a value obtained by dividing the substrate distance by the image forming speed is determined as the first correction amount.

Specifically, the first correction amount determination unit 83A sets each of the first substrate distance and the second substrate distance to the first A value distributed according to the ratio of the arrangement distance and the second arrangement distance is determined as the substrate distance, and a value obtained by dividing the substrate distance by the image forming speed is determined as the first correction amount of the second light source substrate 202 . Further, the first correction amount determination unit 83A sets each of the first substrate distance and the second substrate distance as the first layout distance for each of the plurality of light sources 200 belonging to the representative group of the third light source substrate 203, which is the reference substrate. A value distributed according to the ratio to the second arrangement distance is determined as the substrate distance, and a value obtained by dividing the substrate distance by the image forming speed is determined as the first correction amount of the third light source substrate 203 . Since the first light source substrate 201 is the reference substrate, the first correction amount is zero.

The irradiation distance calculation unit 63C determines a reference group for each of the first light source substrate 201, the second light source substrate 202, and the third light source substrate 203, and performs irradiation of the light source group based on the irradiation position of the light source group and the irradiation position of the reference group. Determine position. In the present embodiment, representative groups of each of the first light source substrate 201, the second light source substrate 202, and the third light source substrate 203 are used as reference groups. Here, the second light source substrate 202 will be described as an example.

The irradiation distance calculator 63C sets the light source group 222, which is the representative group of the second light source substrate 202, as the reference group. Then, the light source groups 221 and 223 other than the representative group are set as reference groups. The irradiation distance calculator 63C determines the distance in the sub-scanning direction between the first irradiation position of the light source group 221, which is the reference group, and the first irradiation position of the light source group 222, which is the reference group, as the irradiation distance of the light source group 222. do. Similarly, the irradiation distance calculator 63B calculates the distance in the sub-scanning direction between the first irradiation position of the light source group 223, which is the reference group, and the first irradiation position of the light source group 222, which is the reference group. Determine the distance. The irradiation distance calculation unit 63</b>C outputs the irradiation distances of the light source groups 222 and 223 to the second correction amount determination unit 85 . Note that the irradiation distance of the light source group 222, which is the reference group, is zero.

A second correction amount determination unit 85 determines a second correction amount based on the irradiation distances of the light source groups 221 and 223 . Specifically, a value obtained by dividing the irradiation distance of the light source group 221 by the image forming speed is determined as the second correction amount of the light source group 221 . Also, a value obtained by dividing the irradiation distance of the light source group 223 by the image forming speed is determined as the second correction amount of the light source group 223 . Since the irradiation distance of the light source group 222, which is the reference group, is zero, the second correction amount of the light source group 222 is determined to be zero.

Correction unit 55D determines the correction amount from the first correction amount and the second correction amount for each of the plurality of light sources 200 . A value obtained by adding the first correction amount and the second correction amount may be used as the correction amount. The first correction amount is a value determined for each of the plurality of light sources 200 belonging to the light source group 222 that is the representative group of the light source substrates 202 . In each of the light source groups 221 and 223 included in the light source substrate 202, the first correction amount of each of the plurality of light sources 200 belonging to the light source group 221 is calculated as follows: The first correction amount for the closest light source 200 is set as the first correction amount for that light source. The second correction amount is a value determined for each of the light source groups 221 and 222 . The correction unit 55D outputs the correction amount determined for each of the plurality of light sources 200 to the exposure control unit 57. FIG.

FIG. 32 is a diagram showing an example of first irradiation position data. Referring to FIG. 32, first irradiation positions 211A, 212A, 213A, 221A, 222A, 223A, 231A, 211A, 222A, 223A, 231A, 211A, 212A, 231A, 231A, 211A, 212A, 231A, 231A, 211A, 212A, 231A, 231A, 213A, 231A, 231A, 231A, 231A, 231A, 231A, 231A, 231A, 231A, 231A, 231A, 231A, 231A, 231A, 231A, 231A, 232A and 233A are shown in black.

FIG. 33 is a diagram showing an example of second irradiation position data. Referring to FIG. 33, compared with the first irradiation position data shown in FIG. are the same as the first irradiation positions 211A, 212A, and 213A corresponding to the light source groups 211, 212, and 213, respectively, in the sub-scanning direction. Further, the second irradiation positions 221B, 222B, and 223B corresponding to the light source groups 221, 222, and 223 included in the second light source substrate 202 are arranged in the sub-scanning direction at the first irradiation positions corresponding to the light source groups 221, 222, and 223, respectively. It is the same as irradiation positions 221A, 222A, and 223A.

The second irradiation positions 231B, 232B, and 233B corresponding to the light source groups 231, 232, and 233 included in the third light source substrate 203 are aligned in the sub-scanning direction with the first irradiation positions corresponding to the light source groups 231, 232, and 233, respectively. It is shifted 10 squares downstream from 231A, 232A, and 233A.

FIG. 34 is a schematic diagram showing an example of an arrangement state of the standard substrate and the reference substrate. Referring to FIG. 34, the directions in which the plurality of light sources 200 are arranged in the first light source substrate 201 as the reference substrate and the third light source substrate 203 are not parallel.

Here, the first substrate distance of the third light source substrate 203 is a, the second substrate distance is b, the distance between the irradiation position of the light source 200 and the first irradiation position is L1, the irradiation position of the light source 200 and the second irradiation position Let the distance to be L2. In this case, the board distance LA of the light source 200 of the third light source board 203 is expressed by the following formula (2).
LA=(aL2+bL1)/(L1+L2) (2)
FIG. 35 is a flowchart showing an example of the flow of light emission timing correction processing according to the second embodiment. Referring to FIG. 35, CPU 111 causes image forming unit 140 to form an image of test data (step S31). In the next step S32A, first irradiation position data is obtained. The first registration sensor 39A is controlled to read the toner image formed on the intermediate transfer belt 30, and read data output by the first registration sensor 39A is obtained. Here, read data obtained by reading a yellow toner image will be described as an example. Using the read data for yellow output by the first registration sensor 39A, the irradiation positions of the light emitted by the light sources 200 Nos. 1 to 27 of the exposure device 21Y are detected as first irradiation positions. For each of the first to twenty-seventh light sources 200, by specifying the position in the sub-scanning direction of the pixel whose brightness is low at a predetermined position in the main scanning direction with respect to the light source 200 in the read data, The irradiation position for the light source 200 is specified. By specifying the first irradiation position for each of the first to twenty-seventh light sources 200, the first irradiation position data is acquired.

In the next step S33A, second irradiation position data is acquired. The second registration sensor 39B is controlled to read the toner image formed on the intermediate transfer belt 30, and read data output by the second registration sensor 39B is obtained. Here, read data obtained by reading a yellow toner image will be described as an example. Using the yellow read data output from the second registration sensor 39B, the irradiation positions of the light emitted by the (N-26)th to Nth light sources 200 of the exposure device 21Y are detected as second irradiation positions. . For each of the (N−26)th to Nth light sources 200, the position in the sub-scanning direction of a pixel whose brightness is low at a predetermined position in the main scanning direction for that light source 200 is specified in the read data. By doing so, the irradiation position for the light source 200 is specified. Second irradiation position data is acquired by specifying the second irradiation position for each of the (N−26)th to Nth light sources 200 .

In the next step S33A, the first correction amount determination process in the second embodiment is executed, and the process proceeds to step S51. Although the details of the first correction amount determination process in the second embodiment will be described later, it is a process of determining the first correction amount for each of the first light source substrate 201, the second light source substrate 202, and the third light source substrate 203.

In step S51, a substrate to be processed is selected from among the first light source substrate 201, the second light source substrate 202 and the third light source substrate 203, and the process proceeds to step S52A. In step S52A, the second correction amount determination process shown in FIG. 28 is executed, and the process proceeds to step S53. By executing the second correction amount determination process, the second correction amount is determined for each of the plurality of light source groups included in each substrate selected as the processing target.

In step S53, it is determined whether or not there is a substrate among the first light source substrate 201, the second light source substrate 202, and the third light source substrate 203 that has not been selected as a processing target in step S51. If there is an unselected substrate, the process returns to step S51; otherwise, the process proceeds to step S54.

In step S54, one of the plurality of light source groups is selected as a processing target, and the process proceeds to step S55A. In step S55A, one of the plurality of light sources 200 belonging to the light source group selected as the processing target is selected as the processing target, and the process proceeds to step S55B. In step S55B, the light emission timing of light source 200 to be processed is corrected using the first correction amount and the second correction amount, and the process proceeds to step S55C. In step S55C, it is determined whether or not there is a light source 200 that has not been selected as a processing target. If there is an unselected light source 200, the process returns to step S55A; otherwise, the process proceeds to step S56.

In step S56, it is determined whether or not there is a light source group that has not been selected as a processing target. If there is an unselected light source group, the process returns to step S54; otherwise, the process ends. Accordingly, by executing steps S55A and S55B for all of the plurality of light source groups, the correction amount for each of the plurality of light sources 200 is determined, and the light emission timings of the plurality of light sources 200 are corrected. However, since the correction amount of the light source group 212, which is the representative group of the first light source substrate 201, which is the reference substrate, is not determined, the light emission timings of the plurality of light sources 200 belonging to the light source group 212 are not corrected.

FIG. 36 is a flowchart showing an example of the flow of first correction amount determination processing according to the second embodiment. The first correction amount determination process in the second embodiment is a process executed in step S33A of FIG. Referring to FIG. 36, CPU 111 determines a representative group of reference substrates (step S41). Here, among the plurality of light source groups, a light source group 212 in which a line connecting a plurality of light sources 200 belonging thereto and the center of rotation of the photosensitive drum 23Y intersects the surface of the photosensitive drum 23Y at a vertical angle or the most perpendicular angle is a light source group 212. is determined as a representative group of reference substrates. The first light source substrate 201 including the light source group 212 is the reference substrate.

In the next step S42A, the first reference substrate position is determined, and the process proceeds to step S42B. The first reference substrate position is the first irradiation position of the reference substrate. Among the first irradiation positions of the plurality of light source groups determined by the first irradiation position data, the first irradiation position of the light source group 212 that is the representative group of the first light source substrate 201 that is the reference substrate is defined as the first reference substrate position. to decide.

In the next step S42B, the second reference substrate position is determined, and the process proceeds to step S43. The second reference substrate position is the second irradiation position of the reference substrate. Among the second irradiation positions of the plurality of light source groups determined by the second irradiation position data, the second irradiation position of the light source group 212 that is the representative group of the first light source substrate 201 that is the reference substrate is defined as the second reference substrate position. to decide.

In the next step S43, a reference substrate is selected and the process proceeds to step S44. Among the first light source substrate 201, the second light source substrate 202 and the third light source substrate 203, the second light source substrate 202 and the third light source substrate 203 other than the reference substrate are reference substrates. One of the second light source substrate 202 and the third light source substrate 203 to be processed is selected. Here, an example in which the second light source substrate 202 is selected as an object to be processed will be described.

In step S44, a representative group of reference substrates selected to be processed is determined, and the process proceeds to step S45A. Here, the light source group 222 included in the second light source board 202 selected to be processed is determined as the representative group. Among the light source groups 221, 222, and 223 included in the second light source substrate 202, the light source group 222 arranged at the center in the sub-scanning direction is determined as the representative group.

In step S45A, the first reference substrate position is determined, and the process proceeds to step S45B. The first reference substrate position is the first irradiation position of the reference substrate. Among the first irradiation positions of the plurality of light source groups determined by the first irradiation position data, the first irradiation position of the light source group 222 determined as the representative group in step S44 is determined as the first reference substrate position.

In step S45B, the second reference substrate position is determined, and the process proceeds to step S46A. The second reference substrate position is the second irradiation position of the reference substrate. Among the second irradiation positions of the plurality of light source groups determined by the second irradiation position data, the second irradiation position of the light source group 222 determined as the representative group in step S44 is determined as the second reference substrate position.

In step S46A, the first substrate distance is calculated, and the process proceeds to step S46B. The first substrate distance is the distance in the sub-scanning direction between the first reference substrate position and the first reference substrate position. Here, the distance between the first irradiation position of the light source group 212 of the first light source substrate 201 which is the reference substrate and the first irradiation position of the light source group 222 of the second light source substrate 202 which is the reference substrate is is calculated as the first substrate distance of the second light source substrate 202 .

In step S46B, the second substrate distance is calculated, and the process proceeds to step S47A. The second substrate distance is the distance in the sub-scanning direction between the second reference substrate position and the second reference substrate position. Here, the distance between the second irradiation position of the light source group 212 of the first light source substrate 201 which is the reference substrate and the second irradiation position of the light source group 222 of the second light source substrate 202 which is the reference substrate is is calculated as the second substrate distance of the second light source substrate 202 .

In step S47A, the first correction amount determination process for each light source is executed, and the process proceeds to step S48. The light source-by-light source first correction amount determination process is a process of determining the first correction amount for each of the plurality of light sources 200 . In step S48, it is determined whether or not there is a reference substrate that has not been selected as a processing target in step S43. If there is an unselected reference substrate, the process returns to step S43; otherwise, the process returns to the light emission timing correction process.

FIG. 37 is a flowchart illustrating an example of the flow of the light source-by-light source first correction amount determination process. The light source-by-light source first correction amount determination process is a process executed in step S47A of FIG. Referring to FIG. 37, CPU 111 selects one from a plurality of light sources 200 as a processing target (step S61), and advances the process to step S62. In step S62, the distance L1 from the irradiation position of the light source 200 to be processed to the first irradiation position is calculated. The distance between the irradiation position of the light source 200 to be processed and the first irradiation position, which is the irradiation position of the first representative light source, is calculated as L1.

In step S63, the distance L2 from the irradiation position of the light source 200 to be processed to the second irradiation position is calculated. The distance between the irradiation position of the light source 200 to be processed and the second irradiation position, which is the irradiation position of the second representative light source, is calculated as L2.

In the next step S64, the first substrate distance a and the second substrate distance b are determined, and the process proceeds to step S65. In step S65, the first correction amount of the light source 200 to be processed is determined by allocating the first substrate distance a and the second substrate distance b according to the ratio of the distance L1 and the distance L2. Specifically, the first correction amount is determined using the above equation (2). A value obtained by dividing the substrate distance LA by the image forming speed is determined as the first correction amount.

In the next step S66, it is determined whether or not there is a light source 200 that has not been selected as a processing target. If there is an unselected light source 200, the process returns to step S61; otherwise, the process returns to the first correction amount determination process.

In the MFP 100 according to the second embodiment, each of the exposure devices 21Y, 21M, 21C, and 21K, for example, the exposure device 21Y, has a first light source substrate on which a plurality of light sources 200 are formed so as to be arranged along a predetermined direction. 201, a second light source substrate 202, and a third light source substrate 203, and the positions of the plurality of light sources respectively formed on the first light source substrate 201, the second light source substrate 202, and the third light source substrate 203 are arranged in a predetermined direction and direction. A first light source substrate 201, a second light source substrate 202, and a third light source substrate 203 are positioned so as to be different from each other in the sub-scanning direction intersecting the predetermined direction. Each of the third light source substrates 203 has a first substrate representative light source within a first range of positions arranged in a predetermined direction among the plurality of light sources formed on the substrate, and a second range of positions arranged in a predetermined direction. and a second substrate representative light source within.

The CPU 111 detects an irradiation position where the photosensitive drum 23Y is irradiated with light emitted from at least two of the plurality of light sources, and uses the first light source substrate 201 as a reference substrate. The position of the sub-scanning direction between the first reference substrate position detected as the irradiation position for the substrate representative light source and the first reference substrate position detected as the irradiation position for the first substrate representative light source formed on the first light source substrate 201 A first substrate distance, a second reference substrate position detected as an irradiation position for the second substrate representative light source formed on the second light source substrate 202, and an irradiation position for the second substrate representative light source formed on the first light source substrate 201 and the second substrate distance in the sub-scanning direction from the second reference substrate position detected as . 1 correction amount is determined, and the first reference substrate position with respect to the first substrate representative light source formed on the third light source substrate 203 and the first reference substrate position with respect to the first substrate representative light source formed on the first light source substrate 201 are determined. the first substrate distance in the sub-scanning direction between, the second reference substrate position relative to the second substrate representative light source formed on the third light source substrate 203, and the second substrate relative to the second substrate representative light source formed on the first light source substrate 201 A first correction amount for correcting the light emission timing of each of the plurality of light sources 200 formed on the third light source substrate 203 is determined based on the second substrate distance in the sub-scanning direction from the reference substrate position. .

Therefore, it is possible to correct the displacement of the relative position between the first light source substrate 201 and the second light source substrate 202 or the third light source substrate 203, and reduce the displacement of the irradiation positions of the plurality of light sources 200 in the sub-scanning direction. can be done.

Further, the plurality of light sources 200 formed on each of the first light source substrate 201, the second light source substrate 202, and the third light source substrate 203 are included in one of the plurality of light source groups at different positions in the sub-scanning direction. The plurality of light source groups included in each of the first light source substrate 201, the second light source substrate 202, and the third light source substrate 203 include a reference group and reference groups other than the reference group. The CPU 111 has a representative light source selected from the plurality of light sources 200 belonging to the group, and the CPU 111 assigns each of the first light source substrate 201, the second light source substrate 202, and the third light source substrate 203 to the substrate, for example, Irradiation in the sub-scanning direction between the reference group position detected as the irradiation position for the representative light source belonging to the reference group included in the first light source substrate 201 and the reference group position detected as the irradiation position for the representative light source belonging to the reference group A second correction amount for correcting the light emission timings of the plurality of light sources 200 belonging to the reference group is determined based on the distance. Therefore, since the second correction amount for each of the plurality of light source groups is determined for each of the first light source substrate 201, the second light source substrate 202, and the third light source substrate 203, the correction amount can be determined accurately. .

The first light source substrate 201, which is a reference substrate, is such that a line connecting the first substrate representative light source or the second substrate representative light source and the rotation center of the photoreceptor drum 23Y intersects the surface of the photoreceptor drum 23Y at a vertical or vertical angle. , are closer to vertical than those of the second light source substrate 202 and the third light source substrate 203 . Therefore, it is possible to reduce the displacement of the irradiation position with respect to the first light source substrate 201 due to the deformation of the photosensitive drum 23Y.

Further, the CPU 111 detects the irradiation position in a state in which the light emitted from the plurality of light sources 200 is emitted at the light emission timing when the light emitted from the plurality of light sources 200 is emitted to the photosensitive drum 23Y at the same position in the sub-scanning direction. do. Therefore, it is sufficient to detect whether or not the irradiation positions of the plurality of light sources 200 are arranged in the main scanning direction, and the light emission timing can be easily corrected.

<Fifth Modification>
In the MFP 100 according to the second embodiment, the first correction amount for the reference substrate is set to zero. The MFP 100 according to the fifth modification obtains the third correction amount of the reference substrate based on the first reference substrate position and the second reference substrate position.

FIG. 38 is a diagram showing an example of detailed functions of a correction unit in the fifth modification. Referring to FIG. 38, correction unit 55E in the fifth modification differs from correction unit 55D in the second embodiment shown in FIG. 31 in that a third correction amount determination unit 87 is added.

The third correction amount determination unit 87 calculates a third correction amount for the reference board based on the first reference board position and the second reference board position. The third correction amount for the reference substrate is zero when the first reference substrate position and the second reference substrate position are the same. As for the third correction amount of the reference substrate, when the first reference substrate position and the second reference substrate position are different, the reference substrate is not parallel to the main scanning direction but is inclined. Therefore, the third correction amount determination unit 87 determines the distance in the sub-scanning direction between the first reference substrate position and the second reference substrate position for each of the plurality of light sources 200 belonging to the representative group of the reference substrate. A substrate distance for the light source is determined based on a first placement distance between the light source 200 and the first substrate representative light source and a second placement distance between the light source 200 and the second substrate representative light source. Specifically, the third correction amount determination unit 87 determines the distance in the sub-scanning direction between the first reference substrate position and the second reference substrate position for each of the plurality of light sources 200 belonging to the representative group of the reference substrate, A value distributed according to the ratio of the first arrangement distance and the second arrangement distance is determined as the substrate distance, and a value obtained by dividing the substrate distance by the image forming speed is determined as the third correction amount of the reference substrate.

Here, the distance in the sub-scanning direction between the first reference substrate position and the second reference substrate position is c, the distance between the irradiation position of the light source 200 and the irradiation position of the first substrate representative light source is L1, and the distance of the light source 200 is L1. Let L2 be the distance between the irradiation position and the irradiation position of the second substrate representative light source. In this case, the board distance LA between the light sources 200 in the representative group 212 of the first light source board 201, which is the reference board, is given by the following equation (3).
LA=cL1/(L1+L2) (3)
The above formula (3) is obtained by replacing b in the above formula (2) with c and a with zero. Note that c=(ba).

Correction unit 55E determines the correction amount from the first correction amount, the second correction amount, and the third correction amount for each of the plurality of light sources 200 . A value obtained by adding the first correction amount, the second correction amount, and the third correction amount for each of the plurality of light sources 200 may be used as the correction amount. The third correction amount is a value determined for each of the plurality of light sources 200 belonging to the light source group 212 that is the representative group of the first light source substrate 201 that is the reference substrate.

In each of the light source groups 221 and 223 included in the first light source substrate 201, the second light source substrate 202 and the third light source substrate 203, the correction unit 55E corrects the light source group 212 which is the representative group of the first light source substrate 201 which is the reference substrate. Among the plurality of light sources 200 belonging to , the third correction amount of the light source 200 closest in the main scanning direction to the light source 200 is set as the third correction amount of that light source.

Thereby, the irradiation position of each of the plurality of light sources 200 formed on the first light source substrate 201, the second light source substrate 202, and the third light source substrate 203 can be made parallel to the main scanning direction.

It should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all modifications within the meaning and range of equivalents of the scope of the claims.

<Appendix>
(1) for each of the plurality of light sources formed on the second substrate, the irradiation position detected by the detection means for the light source and the irradiation position detected by the detection means for the representative light source for the first substrate; and a distance between the irradiation position detected by the detection means for the light source and the irradiation position detected by the detection means for the second substrate representative light source. 9. The exposure apparatus according to claim 8, wherein said first correction amount is determined further based on a second arrangement distance of .
(2) The correcting means performs the detection with respect to the irradiation position detected by the detecting means for the light sources and the first substrate representative light source for each of the plurality of light sources formed on the first substrate. a first arrangement distance between the irradiation position detected by means; and the irradiation position detected by the detection means for the light source and the second substrate representative light source detected by the detection means. 11. The exposure apparatus according to claim 10, further determining said third correction amount based on a second arrangement distance from said irradiation position.

100 MFP, 20Y, 20M, 20C, 20K image forming unit, 21Y, 21M, 21C, 21K exposure device, 22Y, 22M, 22C, 22K charging charger, 23Y, 23M, 23C, 23K photosensitive drum, 24Y, 24M, 24C , 24K developer, 25Y, 25M, 25,C, 25K transfer charger, 26 transfer roller, 30 intermediate transfer belt, 32 fixing roller pair, 39 registration sensor, 39A first registration sensor, 39B second registration sensor, 41Y, 41M , 41C, 41K toner bottle, 110 main circuit, 111 CPU, 120 automatic document feeder, 130 document reading section, 140 image forming section, 150 paper feeding section, 160 operation panel, 201 first light source board, 202 second light source board , 203 third light source substrate, 51 sensor control unit, 53 detection unit, 55, 55A, 55B, 55C, 55D, 55E correction unit, 57, 57A exposure control unit, 61 group position acquisition unit, 63, 63B, irradiation distance calculation 63A representative distance calculator 65, 65A correction amount determiner 67, 67A reference group position determiner 67B board reference group position determiner 69, 69A reference group position determiner 69B board reference group position determiner 73 placement distance acquisition unit 81 substrate distance calculation unit 82 substrate representative group determination unit 200 light source 202 second light source substrate 211, 212, 213, 221, 222, 223, 231, 232, 233 light source group 211A, 212A, 213A, 221A, 222A, 223A, 231A, 232A, 233A irradiation position, 240 microlens array, 245 lens set, 247 diaphragm plate, 247A diaphragm, 248 first lens plate, 249 second lens plate.

Claims (13)

an exposure unit including a plurality of light source groups in which a plurality of light sources are arranged along the main scanning direction;
the plurality of light source groups are arranged along a sub-scanning direction intersecting the main scanning direction such that positions of the plurality of light sources in the main scanning direction are different from each other;
detection means for detecting an irradiation position where an image carrier moving at a predetermined speed relative to the exposure unit along the sub-scanning direction is irradiated with light emitted from at least two of the plurality of light sources;
based on the irradiation distance in the sub-scanning direction between the at least two irradiation positions detected by the detection means for at least two of the light sources belonging to at least two of the plurality of light source groups among the plurality of light sources and correction means for correcting light emission timings of the plurality of light sources included in each of the plurality of light source groups,
each of the plurality of light source groups has a representative light source selected from among the plurality of light sources belonging to the light source group;
The correction means determines a correction amount for correcting light emission timings of the plurality of light sources based on irradiation distances in the sub-scanning direction between the plurality of irradiation positions corresponding to the representative light sources of the plurality of light source groups. An image forming apparatus that is determined for each of the plurality of light source groups. The plurality of light source groups includes a reference group and a reference group other than the reference group;
The correcting means determines a reference group position detected as the irradiation position by the detection means for the representative light source belonging to the reference group and a reference group position for the representative light source belonging to the reference group as the irradiation position by the detection means. 2. The method according to claim 1 , wherein a correction amount for correcting light emission timings of the plurality of light sources belonging to the reference group is determined based on an irradiation distance in the sub-scanning direction from the detected reference group position. Image forming device. an exposure unit including a plurality of light source groups in which a plurality of light sources are arranged along the main scanning direction;
the plurality of light source groups are arranged along a sub-scanning direction intersecting the main scanning direction such that positions of the plurality of light sources in the main scanning direction are different from each other;
detection means for detecting an irradiation position where an image carrier moving at a predetermined speed relative to the exposure unit along the sub-scanning direction is irradiated with light emitted from at least two of the plurality of light sources;
based on the irradiation distance in the sub-scanning direction between the at least two irradiation positions detected by the detection means for at least two of the light sources belonging to at least two of the plurality of light source groups among the plurality of light sources and correction means for correcting light emission timings of the plurality of light sources included in each of the plurality of light source groups,
each of the plurality of light source groups has a representative light source selected from among the plurality of light sources belonging to the light source group;
the plurality of light source groups includes at least two representative groups;
at least two of the representative groups include a reference group and a reference group other than the reference group;
The correcting means, for each of the plurality of light source groups, calculates a layout distance between the light source group and the reference group, a layout distance between the reference group and the reference group, and the representative of the reference group. a representative distance in the sub-scanning direction between the irradiation position detected by the detection means for the light source and the irradiation position detected by the detection means for the representative light source belonging to the reference group; an image forming apparatus that determines a correction amount for correcting light emission timings of the plurality of light sources formed in the light source group based on the light source group. In the reference group, a line connecting the representative light source belonging to the reference group and the rotation center of the image carrier intersects the surface of the image carrier at an angle perpendicular or closest to the perpendicular. 4. The image forming apparatus according to claim 2 , which is a group. an exposure unit including a plurality of light source groups in which a plurality of light sources are arranged along the main scanning direction;
the plurality of light source groups are arranged along a sub-scanning direction intersecting the main scanning direction such that positions of the plurality of light sources in the main scanning direction are different from each other;
detection means for detecting an irradiation position where an image carrier moving at a predetermined speed relative to the exposure unit along the sub-scanning direction is irradiated with light emitted from at least two of the plurality of light sources;
based on the irradiation distance in the sub-scanning direction between the at least two irradiation positions detected by the detection means for at least two of the light sources belonging to at least two of the plurality of light source groups among the plurality of light sources and correction means for correcting light emission timings of the plurality of light sources included in each of the plurality of light source groups,
The exposure unit includes a plurality of substrates formed with a plurality of the light sources belonging to at least one of the plurality of light source groups,
at least one of the light source groups included in each of the plurality of substrates includes a substrate representative group;
each of the plurality of light source groups has a representative light source selected from among the plurality of light sources belonging to the light source group;
The correcting means calculates a plurality of the substrate representative light sources respectively belonging to the plurality of substrate representative groups based on substrate distances in the sub-scanning direction between the plurality of irradiation positions respectively detected by the detecting means. An image forming apparatus that determines, for each substrate, a first correction amount for correcting light emission timings of the plurality of light sources formed on the substrate. the plurality of light source groups included in each of the plurality of substrates includes a reference group and a reference group other than the reference group;
The correcting means, for each of the plurality of substrates, corrects the reference group position detected as the irradiation position by the detecting means with respect to the representative light source belonging to the reference group included in the substrate and the reference included in the substrate. Light emission timings of the plurality of light sources belonging to the reference group based on an irradiation distance in the sub-scanning direction between the representative light source belonging to the group and a reference group position detected as the irradiation position by the detecting means. 6. The image forming apparatus according to claim 5 , wherein the second correction amount for correcting is determined. further comprising exposure control means for controlling the exposure unit to emit light from the plurality of light sources;
The detection means detects a state in which the exposure control means causes the plurality of light sources to emit light at light emission timings at which the light emitted from the plurality of light sources irradiates the image carrier at the same position in the sub-scanning direction. 6. The image forming apparatus according to any one of claims 1 to 5 , wherein the irradiation position is detected at a. A light emission timing correction method performed by an image forming apparatus having an exposure unit including a plurality of light source groups in which a plurality of light sources are arranged along a main scanning direction,
the plurality of light source groups are arranged along a sub-scanning direction intersecting the main scanning direction such that positions of the plurality of light sources in the main scanning direction are different from each other;
a detection step of detecting an irradiation position where an image carrier moving at a predetermined speed in the sub-scanning direction relative to the exposure unit is irradiated with light emitted from at least two of the plurality of light sources;
based on the distance in the sub-scanning direction between the at least two irradiation positions detected in the detecting step for at least two of the light sources belonging to at least two of the plurality of light source groups among the plurality of light sources , a correction step of correcting the light emission timing of the plurality of light sources included in each of the plurality of light source groups ,
each of the plurality of light source groups has a representative light source selected from among the plurality of light sources belonging to the light source group;
The correcting step determines a correction amount for correcting light emission timings of the plurality of light sources based on irradiation distances in the sub-scanning direction between the plurality of irradiation positions corresponding to the representative light sources of the plurality of light source groups. A light emission timing correcting method , comprising the step of determining for each of the plurality of light source groups . A light emission timing correction method performed by an image forming apparatus having an exposure unit including a plurality of light source groups in which a plurality of light sources are arranged along a main scanning direction,
the plurality of light source groups are arranged along a sub-scanning direction intersecting the main scanning direction such that positions of the plurality of light sources in the main scanning direction are different from each other;
a detection step of detecting an irradiation position where an image carrier moving at a predetermined speed in the sub-scanning direction relative to the exposure unit is irradiated with light emitted from at least two of the plurality of light sources;
based on the distance in the sub-scanning direction between the at least two irradiation positions detected in the detecting step for at least two of the light sources belonging to at least two of the plurality of light source groups among the plurality of light sources , a correction step of correcting the light emission timing of the plurality of light sources included in each of the plurality of light source groups,
each of the plurality of light source groups has a representative light source selected from among the plurality of light sources belonging to the light source group;
the plurality of light source groups includes at least two representative groups;
at least two of the representative groups include a reference group and a reference group other than the reference group;
In the correcting step, for each of the plurality of light source groups, the arrangement distance between the light source group and the reference group, the arrangement distance between the reference group and the reference group, and the representative distance belonging to the reference group. a representative distance in the sub-scanning direction between the irradiation position detected in the detection step with respect to the light source and the irradiation position detected in the detection step with respect to the representative light source belonging to the reference group; determining a correction amount for correcting the light emission timing of the plurality of light sources formed in the light source group based on the light emission timing correction method. A light emission timing correction method performed by an image forming apparatus having an exposure unit including a plurality of light source groups in which a plurality of light sources are arranged along a main scanning direction,
the plurality of light source groups are arranged along a sub-scanning direction intersecting the main scanning direction such that positions of the plurality of light sources in the main scanning direction are different from each other;
a detection step of detecting an irradiation position where an image carrier moving at a predetermined speed in the sub-scanning direction relative to the exposure unit is irradiated with light emitted from at least two of the plurality of light sources;
based on the distance in the sub-scanning direction between at least two irradiation positions detected in the detecting step for at least two light sources belonging to at least two of the plurality of light source groups among the plurality of light sources , a correction step of correcting the light emission timing of the plurality of light sources included in each of the plurality of light source groups,
each of the plurality of light source groups has a representative light source selected from among the plurality of light sources belonging to the light source group;
the plurality of light source groups includes at least two representative groups;
The exposure unit includes a plurality of substrates formed with a plurality of the light sources belonging to at least one of the plurality of light source groups,
at least one of the light source groups included in each of the plurality of substrates includes a substrate representative group;
each of the plurality of light source groups has a representative light source selected from among the plurality of light sources belonging to the light source group;
In the correction step, based on substrate distances in the sub-scanning direction between the plurality of irradiation positions detected in the detection step for the plurality of representative light sources belonging to the plurality of substrate representative groups, the A light emission timing correcting method, comprising the step of determining, for each substrate, a first correction amount for correcting light emission timings of the plurality of light sources formed on the substrate. A light emission timing correction program executed by a computer that controls an image forming apparatus having an exposure unit including a plurality of light source groups in which a plurality of light sources are arranged along a main scanning direction,
the plurality of light source groups are arranged along a sub-scanning direction intersecting the main scanning direction such that positions of the plurality of light sources in the main scanning direction are different from each other;
a detection step of detecting an irradiation position where an image carrier moving at a predetermined speed relative to the exposure unit along the sub-scanning direction is irradiated with light emitted from at least two of the plurality of light sources;
based on the distance in the sub-scanning direction between the at least two irradiation positions detected in the detecting step for at least two of the light sources belonging to at least two of the plurality of light source groups among the plurality of light sources and a correction step of correcting the light emission timing of the plurality of light sources included in each of the plurality of light source groups ;
each of the plurality of light source groups has a representative light source selected from among the plurality of light sources belonging to the light source group;
The correcting step determines a correction amount for correcting light emission timings of the plurality of light sources based on irradiation distances in the sub-scanning direction between the plurality of irradiation positions corresponding to the representative light sources of the plurality of light source groups. A light emission timing correction program comprising a step of determining for each of the plurality of light source groups . A light emission timing correction program executed by a computer that controls an image forming apparatus having an exposure unit including a plurality of light source groups in which a plurality of light sources are arranged along a main scanning direction,
the plurality of light source groups are arranged along a sub-scanning direction intersecting the main scanning direction such that positions of the plurality of light sources in the main scanning direction are different from each other;
a detection step of detecting an irradiation position where an image carrier moving at a predetermined speed relative to the exposure unit along the sub-scanning direction is irradiated with light emitted from at least two of the plurality of light sources;
based on the distance in the sub-scanning direction between the at least two irradiation positions detected in the detecting step for at least two of the light sources belonging to at least two of the plurality of light source groups among the plurality of light sources and a correction step of correcting the light emission timing of the plurality of light sources included in each of the plurality of light source groups;
each of the plurality of light source groups has a representative light source selected from among the plurality of light sources belonging to the light source group;
the plurality of light source groups includes at least two representative groups;
at least two of the representative groups include a reference group and a reference group other than the reference group;
In the correcting step, for each of the plurality of light source groups, the arrangement distance between the light source group and the reference group, the arrangement distance between the reference group and the reference group, and the representative distance belonging to the reference group. a representative distance in the sub-scanning direction between the irradiation position detected in the detection step with respect to the light source and the irradiation position detected in the detection step with respect to the representative light source belonging to the reference group; determining a correction amount for correcting the light emission timings of the plurality of light sources formed in the light source group based on the light emission timing correction program. A light emission timing correction program executed by a computer that controls an image forming apparatus having an exposure unit including a plurality of light source groups in which a plurality of light sources are arranged along a main scanning direction,
the plurality of light source groups are arranged along a sub-scanning direction intersecting the main scanning direction such that positions of the plurality of light sources in the main scanning direction are different from each other;
a detection step of detecting an irradiation position where an image carrier moving at a predetermined speed relative to the exposure unit along the sub-scanning direction is irradiated with light emitted from at least two of the plurality of light sources;
based on the distance in the sub-scanning direction between the at least two irradiation positions detected in the detecting step for at least two of the light sources belonging to at least two of the plurality of light source groups among the plurality of light sources and a correction step of correcting the light emission timing of the plurality of light sources included in each of the plurality of light source groups;
each of the plurality of light source groups has a representative light source selected from among the plurality of light sources belonging to the light source group;
the plurality of light source groups includes at least two representative groups;
The exposure unit includes a plurality of substrates formed with a plurality of the light sources belonging to at least one of the plurality of light source groups,
at least one of the light source groups included in each of the plurality of substrates includes a substrate representative group;
each of the plurality of light source groups has a representative light source selected from among the plurality of light sources belonging to the light source group;
In the correction step, based on substrate distances in the sub-scanning direction between the plurality of irradiation positions detected in the detection step for the plurality of representative light sources belonging to the plurality of substrate representative groups, the A light emission timing correction program, comprising the step of determining, for each substrate, a first correction amount for correcting light emission timings of the plurality of light sources formed on the substrate.

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