JP2012063588A - Optical writing unit, image-forming device and control method of optical writing unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a low cost and prevent deterioration in image quality when correcting unevenness of scanning speed in an optical writing unit.SOLUTION: An optical writing unit that forms an electrostatic latent image on a photoreceptor executes: a step for acquiring phase shift information that is information for correcting unevenness of scanning speed; a step for executing a phase shift of a part of a pixel clock and also outputting a phase shift state signal showing a phase shift state of the pixel clock; a step for acquiring pixel information that is information about pixels constituting an image; a step for outputting a first lighting signal for controlling a lighting state of light source based on the pixel information; a step for outputting a lighting adjustment signal for adjusting the first lighting signal based on the phase shift state signal and the number of counts of a basic clock, so that a lighting period of the pixel clock after the phase shift becomes identical to a lighting period of other pixel clocks; and a step for outputting a second lighting signal resulting from partial inversion of the first lighting signal, based on the lighting adjustment signal.

Description

  The present invention relates to an optical writing device, an image forming apparatus, and a method for controlling the optical writing device, and more particularly to correction of uneven scanning speed.

  In recent years, there has been a tendency to digitize information, and image processing apparatuses such as printers and facsimiles used for outputting digitized information and scanners used for digitizing documents have become indispensable devices. Such an image processing apparatus is often configured as a multifunction machine that can be used as a printer, a facsimile, a scanner, or a copier by providing an imaging function, an image forming function, a communication function, and the like.

  Among such image processing apparatuses, electrophotographic image forming apparatuses are widely used in image forming apparatuses used for outputting digitized documents. In an electrophotographic image forming apparatus, an electrostatic latent image is formed by exposing a photoreceptor, and the electrostatic latent image is developed using a developer such as toner to form a toner image. Paper output is performed by transferring the toner image onto paper.

  In an electrophotographic image forming apparatus, an optical writing device for exposing a photosensitive member includes a light source for irradiating a beam for exposing the photosensitive member and a polygon scanner for deflecting the irradiated beam to scan the entire surface of the photosensitive member. Including deflectors. In such an optical writing device, variations in the distance between the reflecting surface of the deflector and the rotation axis cause unevenness in the scanning speed of the light spot, which is the position of the beam irradiated onto the surface to be scanned.

  This uneven scanning speed will be described in more detail. In a general optical writing apparatus, writing of an electrostatic latent image by exposing a photosensitive member with a light beam is performed according to a pixel clock. That is, the presence or absence of light beam irradiation based on whether each pixel is colored or colorless is switched according to the pixel clock. Since the pixel clock has a constant frequency in principle, the scanning speed of the light spot is required to be constant on the main scanning line.

  However, as long as the polygon scanner is used, variations in the distance between the reflecting surface of the deflector and the rotation axis naturally occur, and thus the above-described uneven speed is inevitable. That is, on one main scanning line, the movement of the light spot is fast in a certain portion, and the movement of the light spot is slow in a certain portion. If the scanning speed unevenness is not properly corrected, dot position deviation in the main scanning direction occurs, resulting in image fluctuation and image quality deterioration.

  In order to correct the scanning speed unevenness, the dot position in the main scanning direction is corrected by modulating the pixel clock on the scanning line in accordance with the generated scanning speed unevenness (for example, Patent Documents). 1 or Patent Document 2).

  In addition, for the purpose of reducing the occurrence of black density variation and moire due to pixel clock modulation during reduced copy, it has been proposed to determine whether to turn on / off according to the pixel clock in accordance with the arrangement of pixel data ( For example, see Patent Document 3). According to the invention disclosed in Patent Document 3, the density of each pixel can be made constant.

  In a digital circuit, it is virtually impossible to perform complete random control, and when using the techniques disclosed in Patent Documents 1 and 2, the phase-shifted pixel clock is not continuous in the sub-scanning direction, but the period Will have sex. If this periodicity is weakened and control is performed more randomly, the cost of the control circuit increases.

  On the other hand, the phase-shifted pixel clock does not cause vertical stripes as described above. Further, even in a solid image or an image having no law, the image is not continuous in the sub-scanning direction, and thus does not cause deterioration in image quality. However, in the case of an image subjected to dithering processing, periodicity such as 2by2 or 3by3 occurs in the dot arrangement.

  Moire occurs depending on the relationship between the cycle of the image subjected to the dithering process and the cycle of the pixel clock subjected to the phase shift. When moire occurs due to the phase-shifted pixel clock, the distribution density of the pixel clock phase-shifted in units of several tens of lines changes, resulting in a reduction in image quality that is greater than the vertical stripes.

  On the other hand, by using the technique disclosed in Patent Document 3, a change in density due to phase shift can be prevented. However, since the technique disclosed in Patent Document 3 is based on the premise that the image is reduced, and therefore the lighting time is shortened for the entire image, it is directly applied to the phase shift in correcting the scanning speed unevenness. I can't do it. In addition, since some of the lit pixels are turned off according to the basic clock, the number of basic clocks included in the lighting period of one lit pixel is reduced, and the resolution is lowered.

  Further, in the phase shift for correcting the scanning speed unevenness, there are cases where the frequency of the pixel clock is increased and decreased. Therefore, as disclosed in Patent Document 3, both of them can be achieved only by shortening the lighting time. Can not respond.

  The present invention has been made in consideration of the above circumstances, and an object thereof is to prevent a reduction in image quality at low cost when correcting uneven scanning speed in an optical writing apparatus.

  In order to solve the above problems, one embodiment of the present invention is an optical writing device that forms an electrostatic latent image on a photosensitive member by irradiating a light beam, and is irradiated from a light source that exposes the photosensitive member. The light beam guided by the scanning unit that guides the light beam onto the photosensitive member and scans the photosensitive member corrects the scanning speed unevenness that is a change on the scanning line of the scanning speed of the photosensitive member. A phase shift information acquisition unit that acquires phase shift information that is information for generating a pixel clock indicating a pixel timing on the scan line based on a basic clock, and one main scan line among the generated pixel clocks Phase-shifted by increasing / decreasing the number of clocks of the basic clock contained in at least one pixel clock based on the acquired phase shift information The image is configured based on a phase shift unit that outputs a source clock and a phase shift state signal indicating a phase shift state of the output pixel clock, and information on an image to be formed as the electrostatic latent image. A pixel information acquisition unit that acquires pixel information, which is pixel information, according to the pixel clock; and a first lighting signal for controlling a lighting state of a light source that emits the light beam based on the acquired pixel information. Based on the first lighting signal output unit that outputs in accordance with the pixel clock, the phase shift state signal, and the count number of the basic clock, the lighting period of the light source corresponding to the phase-shifted pixel clock corresponds to the other pixel clocks A lighting adjustment signal output for outputting a lighting adjustment signal for adjusting the first lighting signal so as to be the same as the lighting period of the light source If, based on the lighting adjustment signal, wherein a portion of the first lighting signal and a second lighting signal output section for outputting the second lighting signal inverted.

  Further, it is preferable that the lighting adjustment signal output unit outputs the lighting adjustment signal indicating that the lighting state at the front end or the end of the lighting period of the light source corresponding to the phase-shifted pixel clock is designated.

  The lighting adjustment signal output unit further refers to at least one of the pixel information and the first lighting signal, and a lighting state in a part of the lighting period of the light source corresponding to the phase-shifted pixel clock It is preferable to output the lighting adjustment signal indicating that the signal is inverted.

  Further, the lighting adjustment signal output unit inverts the lighting period of the light source corresponding to the phase-shifted pixel clock by a period corresponding to the basic clock number increased or decreased based on the phase shift information. It is preferable to output the lighting adjustment signal shown.

  In addition, the phase shift information acquisition unit acquires the phase shift information according to the pixel clock, and the phase shift unit outputs the phase shift state signal according to the pixel clock, so that the pixel clock one clock before The phase shift state signal corresponding to the acquired phase shift information is output, and the lighting adjustment signal output unit further refers to the phase shift information to determine the state of the phase shift in the current pixel clock and the next It is preferable to output the lighting adjustment signal based on the phase shift state in the pixel clock.

  The pixel information acquisition unit outputs the first lighting signal for controlling the lighting state of the light source corresponding to the pixel information acquired in the pixel clock one clock before, and the lighting adjustment signal The output unit further refers to the pixel information and the first lighting signal, and outputs the lighting adjustment signal based on the lighting state of the light source in the current pixel clock and the lighting state of the light source in the next pixel clock. It is preferable to output.

  The lighting adjustment signal output unit may be configured to output the light source corresponding to the phase-shifted pixel clock when the phase-shifted pixel clock is phase-shifted by reducing the number of clocks of the basic clock. It is preferable to output the lighting adjustment signal indicating that the light source is turned on in a period adjacent to the front end or the end of the lighting period.

  The lighting adjustment signal output unit may be configured to output the light source corresponding to the phase-shifted pixel clock when the phase-shifted pixel clock is phase-shifted by increasing the number of clocks of the basic clock. It is preferable to output the lighting adjustment signal indicating that the light source is turned off at the leading end or the terminal end of the lighting period.

  According to another aspect of the present invention, there is provided an image forming apparatus including any one of the optical writing apparatuses described above.

  According to still another aspect of the present invention, there is provided a method for controlling an optical writing device that forms an electrostatic latent image on a photosensitive member by irradiating a light beam, and the light emitted from a light source that exposes the photosensitive member. In order to correct uneven scanning speed, which is a change on the scanning line of the speed at which the light beam guided by the scanning unit that guides the beam onto the photosensitive member and scans the photosensitive member on the photosensitive member. Phase shift information is acquired, a pixel clock indicating the timing of the pixels on the scan line is generated based on a basic clock, and at least one pixel clock in one main scan line is generated among the generated pixel clocks. Output the pixel clock shifted in phase by increasing or decreasing the number of clocks of the included basic clock based on the acquired phase shift information A phase shift state signal indicating a phase shift state of the output pixel clock is output, and pixel information, which is information on pixels constituting the image, is obtained based on the information on the image to be formed as the electrostatic latent image. And a first lighting signal for controlling a lighting state of a light source that irradiates the light beam is output according to the pixel clock based on the acquired pixel information, and the phase shift state signal and the basic clock are output. Lighting adjustment for adjusting the first lighting signal so that the lighting period of the light source corresponding to the phase-shifted pixel clock is the same as the lighting period of the light source corresponding to the other pixel clocks And a second lighting signal obtained by inverting a part of the first lighting signal based on the lighting adjustment signal. .

  According to the present invention, at the time of correcting the scanning speed unevenness in the optical writing device, the image quality can be prevented from being lowered at a low cost.

1 is a block diagram illustrating a hardware configuration of an image forming apparatus according to an embodiment of the present invention. 1 is a diagram illustrating a functional configuration of an image forming apparatus according to an embodiment of the present invention. 1 is a diagram illustrating a configuration of a print engine according to an embodiment of the present invention. It is a top view which shows the structure of the optical writing apparatus which concerns on embodiment of this invention. It is a sectional side view which shows the structure of the optical writing apparatus which concerns on embodiment of this invention. It is a figure which shows the phase shift characteristic in the optical writing apparatus which concerns on embodiment of this invention. It is a block diagram which shows the control part of the optical writing apparatus which concerns on embodiment of this invention. It is a figure which shows the timing chart of the signal in the optical writing apparatus control part which concerns on a prior art example. It is a figure which shows the judgment conditions of the lighting adjustment signal which concerns on embodiment of this invention. It is a figure which shows the timing chart of the signal in the optical writing device control part which concerns on embodiment of this invention. It is a figure which shows the judgment conditions of the lighting adjustment signal which concerns on other embodiment of this invention. It is a figure which shows the timing chart of the signal in the optical writing device control part which concerns on other embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the present embodiment, a multi function peripheral (MFP) as an image forming apparatus will be described as an example. The image forming apparatus according to the present embodiment is an electrophotographic compound machine, and a phase shift for correcting uneven scanning speed of the optical writing apparatus in the optical writing apparatus for forming an electrostatic latent image on the photosensitive member. Processing is the gist. Note that the image forming apparatus need not be a multifunction machine, and may be, for example, a copying machine, a printer, a facsimile machine, or the like.

  FIG. 1 is a block diagram illustrating a hardware configuration of an image forming apparatus 1 according to the present embodiment. As shown in FIG. 1, the image forming apparatus 1 according to the present embodiment includes an engine that executes image formation in addition to the same configuration as an information processing terminal such as a general server or a PC (Personal Computer). That is, the image forming apparatus 1 according to the present embodiment includes a CPU (Central Processing Unit) 10, a RAM (Random Access Memory) 11, a ROM (Read Only Memory) 12, an engine 13, an HDD (Hard Disk Drive) 14, and an I / O. F15 is connected via the bus 18. Further, an LCD (Liquid Crystal Display) 16 and an operation unit 17 are connected to the I / F 15.

  The CPU 10 is a calculation unit and controls the operation of the entire image forming apparatus 1. The RAM 11 is a volatile storage medium capable of reading and writing information at high speed, and is used as a work area when the CPU 10 processes information. The ROM 12 is a read-only nonvolatile storage medium, and stores programs such as firmware. The engine 13 is a mechanism that actually executes image formation in the image forming apparatus 1.

  The HDD 14 is a nonvolatile storage medium capable of reading and writing information, and stores an OS (Operating System), various control programs, application programs, and the like. The I / F 15 connects and controls the bus 18 and various hardware and networks. The LCD 16 is a visual user interface for the user to check the state of the image forming apparatus 1. The operation unit 17 is a user interface such as a keyboard and a mouse for the user to input information to the image forming apparatus 1.

  In such a hardware configuration, a program stored in a recording medium such as the ROM 12, the HDD 14, or an optical disk (not shown) is read into the RAM 11 and operates according to the control of the CPU 10, thereby configuring a software control unit. A functional block that realizes the functions of the image forming apparatus 1 according to the present embodiment is configured by a combination of the software control unit configured as described above and hardware.

  Next, the functional configuration of the image forming apparatus 1 according to the present embodiment will be described with reference to FIG. FIG. 2 is a block diagram illustrating a functional configuration of the image forming apparatus 1 according to the present embodiment. As shown in FIG. 2, the image forming apparatus 1 according to the present embodiment includes a controller 20, an ADF (Auto Document Feeder) 21, a scanner unit 22, a paper discharge tray 23, a display panel 24, and a paper feed table. 25, a print engine 26, a paper discharge tray 27, and a network I / F 28.

  The controller 20 includes a main control unit 30, an engine control unit 31, an input / output control unit 32, an image processing unit 33, and an operation display control unit 34. As shown in FIG. 2, the image forming apparatus 1 according to the present embodiment is configured as a multifunction machine having a scanner unit 22 and a print engine 26. In FIG. 2, the electrical connection is indicated by solid arrows, and the flow of paper is indicated by broken arrows.

  The display panel 24 is an output interface that visually displays the state of the image forming apparatus 1 and is an input when the user directly operates the image forming apparatus 1 or inputs information to the image forming apparatus 1 as a touch panel. It is also an interface (operation unit). The network I / F 28 is an interface for the image forming apparatus 1 to communicate with other devices via the network, and uses an Ethernet (registered trademark) or a USB (Universal Serial Bus) interface.

  The controller 20 is configured by a combination of software and hardware. Specifically, a control program such as firmware stored in a nonvolatile recording medium such as the ROM 12 and the nonvolatile memory and the HDD 14 and the optical disk is loaded into a volatile memory (hereinafter referred to as a memory) such as the RAM 11 to control the CPU 10. The controller 20 is configured by a software control unit configured according to the above and hardware such as an integrated circuit. The controller 20 functions as a control unit that controls the entire image forming apparatus 1.

  The main control unit 30 plays a role of controlling each unit included in the controller 20 and gives a command to each unit of the controller 20. The engine control unit 31 serves as a drive unit that controls or drives the print engine 26, the scanner unit 22, and the like. The input / output control unit 32 inputs a signal or a command input via the network I / F 28 to the main control unit 30. The main control unit 30 controls the input / output control unit 32 and accesses other devices via the network I / F 28.

  The image processing unit 33 generates drawing information based on the print information included in the input print job under the control of the main control unit 30. The drawing information is information for drawing an image to be formed in the image forming operation by the print engine 26 as an image forming unit. The print information included in the print job is image information converted into a format that can be recognized by the image forming apparatus 1 by a printer driver installed in an information processing apparatus such as a PC. The operation display control unit 34 displays information on the display panel 24 or notifies the main control unit 30 of information input via the display panel 24.

  When the image forming apparatus 1 operates as a printer, first, the input / output control unit 32 receives a print job via the network I / F 28. The input / output control unit 32 transfers the received print job to the main control unit 30. When receiving the print job, the main control unit 30 controls the image processing unit 33 to generate drawing information based on the print information included in the print job.

  When drawing information is generated by the image processing unit 33, the engine control unit 31 performs image formation on the paper conveyed from the paper feed table 25 based on the generated drawing information. That is, the print engine 26 functions as an image forming unit. The paper on which image formation has been performed by the print engine 26 is discharged to a paper discharge tray 27.

  When the image forming apparatus 1 operates as a copying machine, the image processing unit 33 is based on the imaging information received by the engine control unit 31 from the scanner unit 22 or the image information generated by the image processing unit 33 based on the imaging information. Generates drawing information. Based on the drawing information, the engine control unit 31 drives the print engine 26 as in the case of the printer operation.

  Next, the configuration of the print engine 26 according to the present embodiment will be described with reference to FIG. As shown in FIG. 3, the print engine 26 according to the present embodiment includes a configuration in which image forming units 106 of respective colors are arranged along a conveyor belt 105 that is an endless moving unit, which is a so-called tandem type. It is what is said. That is, along the conveying belt 105 that conveys a sheet (an example of a recording medium) 104 that is separated and fed from the sheet feeding tray 101 by the sheet feeding roller 102 and the separation roller 103, the upstream side in the conveying direction of the conveying belt 105. A plurality of image forming units (electrophotographic process units) 106BK, 106M, 106C, and 106Y are arranged in this order.

  The plurality of image forming units 106BK, 106M, 106C, and 106Y have the same internal configuration except that the colors of the toner images to be formed are different. The image forming unit 106BK forms a black image, the image forming unit 106M forms a magenta image, the image forming unit 106C forms a cyan image, and the image forming unit 106Y forms a yellow image. In the following description, the image forming unit 106BK will be described in detail. However, since the other image forming units 106M, 106C, and 106Y are the same as the image forming unit 106BK, the image forming units 106M, 106C, and 106Y are similar to the image forming unit 106BK. As for each of the components, only the symbols distinguished by M, C, and Y are displayed in the drawing in place of the BK attached to each component of the image forming unit 106BK, and the description thereof is omitted.

  The conveying belt 105 is an endless belt, that is, an endless belt that is stretched between a driving roller 107 and a driven roller 108 that are rotationally driven. The drive roller 107 is driven to rotate by a drive motor (not shown), and the drive motor, the drive roller 107, and the driven roller 108 function as a drive unit that moves the conveyance belt 105 that is an endless moving unit. .

  At the time of image formation, the paper 104 stored in the paper feed tray 101 is sent out in order from the top, and the first image forming unit 106BK is conveyed by the conveyance belt 105 that is attracted to and rotated by the conveyance belt 105 by electrostatic adsorption action. Where the black toner image is transferred. That is, the conveyance belt 105 functions as a conveyance body that conveys a sheet that is an image transfer target.

  The image forming unit 106BK includes a photoconductor drum 109BK as a photoconductor, a charger 110BK arranged around the photoconductor drum 109BK, an optical writing device 111, a developing device 112BK, a photoconductor cleaner (not shown), and a static eliminator. 113BK and the like. The optical writing device 111 is configured to irradiate the respective photosensitive drums 109BK, 109M, 109C, and 109Y (hereinafter collectively referred to as “photosensitive drum 109”) with a laser beam.

  At the time of image formation, the outer peripheral surface of the photosensitive drum 109BK is uniformly charged by the charger 110BK in the dark, and then writing is performed by a laser beam corresponding to the black image from the optical writing device 111. An image is formed. The developing device 112BK visualizes the electrostatic latent image with black toner, thereby forming a black toner image on the photosensitive drum 109BK.

  This toner image is transferred onto the sheet 104 by the action of the transfer unit 115BK at a position (transfer position) where the photosensitive drum 109BK and the sheet 104 on the conveying belt 105 contact each other. By this transfer, an image of black toner is formed on the paper 104. After the transfer of the toner image is completed, unnecessary toner remaining on the outer peripheral surface of the photosensitive drum 109BK is wiped off by the photosensitive cleaner, and then the charge is removed by the charge eliminator 113BK, and waits for the next image formation.

  As described above, the sheet 104 on which the black toner image is transferred by the image forming unit 106BK is transported to the next image forming unit 106M by the transport belt 105. In the image forming unit 106M, a magenta toner image is formed on the photosensitive drum 109M by a process similar to the image forming process in the image forming unit 106BK, and the toner image is superimposed on the black image formed on the paper 104. And is transcribed.

  The sheet 104 is further conveyed to the next image forming units 106C and 106Y, and a cyan toner image formed on the photoconductive drum 109C and a yellow toner image formed on the photoconductive drum 109Y by the same operation. Are superimposed on the sheet 104 and transferred. In this way, a full color image is formed on the sheet 104. The sheet 104 on which the full-color superimposed image is formed is peeled off from the conveying belt 105 and the image is fixed by the fixing device 116, and then discharged to the outside of the image forming apparatus.

  Next, the optical writing device 111 according to the present embodiment will be described. FIG. 4 is a view of the optical writing device 111 according to the present embodiment as viewed from above. FIG. 5 is a cross-sectional view of the optical writing device according to the present embodiment as viewed from the side. As shown in FIGS. 4 and 5, the laser beams for writing on the photosensitive drums 109BK, 109M, 109C, and 109Y of the respective colors are light source devices 281BK, 281M, 281C, and 281Y as light sources (hereinafter collectively referred to as “light source device 281”). ). Note that the light source device 281 according to the present embodiment includes a semiconductor laser, a collimator lens, a slit, a prism, a cylinder lens, and the like.

  The laser beam emitted from the light source device 281 is reflected by the reflecting mirror 280. Each laser beam is guided to mirrors 282BK, 282M, 282C, and 282Y (hereinafter collectively referred to as “mirror 282”) by an optical system such as an fθ lens (not shown), and further, the photosensitive drums 109BK and 109M are further guided by the optical system ahead. , 109C, 109Y. That is, the reflecting mirror 280 and the mirror 282 function as a scanning unit.

  The reflecting mirror 280 is a hexahedral polygon mirror, and by rotating, the laser beam for one line in the main scanning direction can be scanned per polygon mirror surface. The optical writing device 111 according to this embodiment divides the four light source devices into light source devices of two colors of 281BK, 281M, and 281C, 281Y, and performs scanning using different reflecting surfaces of the reflecting mirror 280. It is possible to write on four different photosensitive drums at the same time with a more compact configuration than the scanning method using only one reflecting surface.

  In addition, a horizontal synchronization detection sensor 283 is provided in the vicinity of the scanning start position in the range where the laser beam is scanned by the reflecting mirror 280. When the laser beam emitted from the light source device 281 enters the horizontal synchronization detection sensor 283, the timing of the scanning start position of the main scanning line is detected, and the control device that controls the light source device 281 and the reflecting mirror 280 are synchronized. Be taken.

  In such an optical writing device, as described above, the laser beam is scanned in the entire main scanning direction by the rotation of the reflecting mirror 280. Since the reflecting mirror 280 is a hexahedron, the reflecting surface that reflects the laser beam is a flat surface, the distance from each part of the plane to the rotation axis is different, and the laser beam is scanned from one end to the other end of the main scanning line. During this time, the moving speed of the light spot that is the arrival point of the laser beam on the scanning surface (hereinafter referred to as “scanning speed”) changes. This change in scanning speed on the main scanning line, that is, correction of uneven scanning speed is the gist of the present embodiment. Note that the change in scanning speed may be caused not only by the difference in the optical path length of the light beam but also by the installation error of the mirror 282 and manufacturing tolerances.

  A problem caused by the above-described change in scanning speed will be described with reference to FIG. If the scanning speed is constant on the main scanning line, the interval between pixels is constant on the main scanning line as long as writing is performed with a constant pixel clock. However, when the scanning speed changes, if writing is performed with a constant pixel clock, the interval between pixels is wide in a range where the scanning speed is high, and the interval between pixels is narrow in a range where the scanning speed is slow. Therefore, it is necessary to correct the interval between pixels in accordance with the change in scanning speed.

  FIG. 6 is a diagram illustrating an example of the necessary correction amount according to the position of the main scanning line. In other words, information as shown in FIG. 6 is used as phase shift information for correcting the scanning speed to be substantially constant in the optical writing device 111. As shown in FIG. 6, when the scanning speed changes, the necessary correction amount changes according to the position of the main scanning line. The range of “a large amount of correction in the minus direction” shown in FIG. 6 is a range that needs to be corrected so that the interval between pixels is narrow, and is a range in which the scanning speed is faster than the reference speed. Further, since the correction amount is large, the difference between the scanning speed and the reference speed is large.

  On the other hand, the range of “a small amount of correction in the positive direction” is a range in which correction is necessary so that the interval between pixels is wide, and the scanning speed is a range slower than the reference speed. Further, since the correction amount is small, the difference between the scanning speed and the reference speed is small. In the present embodiment, the pixel interval is corrected to an appropriate interval by shifting the phase of the pixel clock, that is, changing the clock frequency based on the characteristics of the correction amount. The required correction amount characteristic as shown in FIG. 6 differs depending on the configuration of the optical system in the optical writing device 111.

  Next, a control block of the optical writing device 111 according to the present embodiment will be described with reference to FIG. FIG. 7 is a diagram illustrating a functional configuration of the optical writing device control unit 120 that controls the optical writing device 111 according to the present embodiment and a connection relationship with the light source device 281. As illustrated in FIG. 7, the optical writing device 120 according to the present embodiment includes a phase shift unit 121, a phase shift information output unit 122, a pixel information acquisition unit 123, a first lighting signal generation unit 124, and a lighting adjustment signal generation unit 125. And a second lighting signal generator 126.

  The optical writing device 111 according to the present embodiment includes information processing mechanisms such as the CPU 10, RAM 11, ROM 12, and HDD 14 as described in FIG. 1, and the optical writing device control unit 120 as shown in FIG. Similar to the controller 20 of the forming apparatus 1, the control program stored in the ROM 12 or the HDD 14 is loaded into the RAM 11, and the software control unit configured by operating according to the control of the CPU 10 and the hardware are combined. Functional blocks of the optical writing device control unit 120 according to the embodiment are configured.

  The phase shift unit 121 generates a pixel clock based on a basic clock input from the outside. At this time, the phase shift unit 121 performs the phase shift of the pixel clock based on the phase shift information output from the phase shift information output unit 122. That is, the phase shift unit 121 also functions as a phase shift information acquisition unit. Further, the phase shift unit 121 indicates whether or not the pixel clock being output is phase-shifted, and if it is phase-shifted, indicates that the clock cycle is lengthened. Two types of status signals are generated and output: a “SHIFT (+)” signal and a “SHIFT (−)” signal whose clock cycle is shortened.

  The phase shift information output unit 122 stores the phase shift information as described with reference to FIG. 6, and outputs phase shift information corresponding to each pixel according to the pixel clock. Thereby, the phase shift unit 121 generates a pixel clock whose phase is shifted according to the position on the main scanning line. The pixel information acquisition unit 123 acquires pixel information that is information of each pixel constituting the image based on the image information input from the controller 20, and outputs the pixel information according to the pixel clock.

  Based on the pixel information output from the pixel information acquisition unit 123, the first lighting signal generation unit 124 generates and outputs a first lighting signal that is a binary signal indicating whether the pixel is turned on / off according to the pixel clock. When the period of one pixel clock changes due to the phase shift of the pixel clock based on the pixel information, the first lighting signal, the basic clock, the status signal, and the phase shift signal, the lighting adjustment signal generation unit 125 A lighting adjustment signal for adjusting the lighting time in the clock so as to be the same as the others is generated and output.

  Based on the first lighting signal and the lighting adjustment signal, the second lighting signal generation unit 126 generates a second lighting signal that is a binary signal indicating lighting / extinguishing of the pixel and whose lighting time is adjusted. Output. As described above, the optical writing device 120 according to the present embodiment provides the lighting adjustment signal for adjusting the lighting time based on various conditions such as the pixel information, the first lighting signal, the basic clock, the status signal, and the phase shift signal. Generate.

  Here, the adverse effects of using a conventional general optical writing device will be described with reference to FIGS. FIG. 8 is a timing chart showing each signal when the clock cycle is lengthened by the phase shift. Note that the conventional general optical writing device is different from the optical writing device 120 according to the present embodiment shown in FIG. 7 in that the phase shift unit 121 does not output a status signal, the lighting adjustment signal generation unit 125, and the second The difference is that the lighting signal generator 126 is not included. That is, in the conventional general optical writing device, the first lighting signal according to the present embodiment is used as it is.

  FIG. 8A is a timing chart showing each signal when the clock cycle is lengthened by the phase shift in the conventional optical writing apparatus. As shown in FIG. 8A, the phase shift unit 121 normally generates a pixel clock with a basic clock 8 count as one cycle. When the “SHIF (+)” signal is input from the phase shift information output unit 122, the phase shift unit 121 sets 9 counts as one period instead of 8 counts in the next pixel clock.

  FIG. 8B is a timing chart showing each signal when the clock cycle is shortened by the phase shift in the conventional optical writing apparatus. As shown in FIG. 8B, when the “SHIF (−)” signal is input from the phase shift information output unit 122, the phase shift unit 121 sets 7 counts instead of 8 counts to 1 in the next pixel clock. Let it be a period.

  When the phase shift is performed as shown in FIGS. 8A and 8B, the lighting time is 9 counts in the basic clock in the case of FIG. 8A, and the lighting is in the case of FIG. 8B. Time is 7 counts of the basic clock. That is, unlike the other pixels that are not phase-shifted, the pixel density changes. The gist of the present embodiment is to prevent this change in pixel density.

  Next, the operation of the optical writing device control unit 120 according to the present embodiment will be described. In FIG. 9, the lighting adjustment signal generation unit 125 according to the present embodiment adjusts the lighting time by inverting the first lighting signal on the terminal side of the phase-shifted pixel clock (hereinafter referred to as “termination adjustment”). It is a figure which shows the conditions at the time of outputting the lighting adjustment signal for performing.

  As described above, the lighting adjustment signal generation unit 125 according to the present embodiment generates a lighting adjustment signal based on the pixel information, the first lighting signal, the basic clock, the status signal, and the phase shift signal. Here, the items that are blank in FIG. 9 are items that do not particularly require conditions. Since it is assumed that the lighting time is adjusted at the end of the pixel clock, as shown in FIG. 9, it is assumed that the current pixel clock is a lighting pixel, that is, the first lighting signal is “1”. It becomes.

  If the next pixel clock is also a lit pixel, it is sufficient to continue lighting without adjusting the lighting time. Therefore, the next pixel clock is an extinguished pixel, that is, pixel information is “OFF”. This is a prerequisite. In such a case, when the status signal is “SHIFT (+)”, the lighting adjustment signal generation unit 125 outputs the lighting adjustment signal at the next basic clock when the clock count number becomes “8”.

  When the status signal is “SHIFT (−)”, the lighting adjustment signal generation unit 125 outputs the lighting adjustment signal at the next basic clock when the clock count number is “7”. The generation of such a lighting adjustment signal will be described with reference to FIGS. 10 (a) and 10 (b). 10A shows an optical writing apparatus according to the present embodiment when “SHIFT (+)” is output as a status signal, and FIG. 10B shows an example when “SHIFT (−)” is output. 3 is a timing chart showing each signal in a control unit 120.

  As shown in FIG. 10A, when “01” is output as the phase shift information in the second pixel clock, that is, information indicating that the next pixel clock is lengthened by 1/8 basic clock, the phase shift is output. The unit 121 outputs “SHIFT (+)” as the status signal in the third pixel clock, and sets the cycle of the pixel clock to 9 basic clocks.

  In this case, as shown in FIG. 10A, the lighting adjustment signal generator 125 is a signal indicating that the first lighting signal is “1”, that is, “lights” in the third pixel clock that is the current pixel clock. If the pixel information indicating ON / OFF in the next pixel clock is a signal indicating “OFF”, that is, “OFF”, the count number of the basic clock to turn off the light source device 281 for the ninth count of the basic clock. Then, “1” is output as the lighting adjustment signal in the next basic clock in which “8” becomes 8, that is, the clock of the ninth count.

  The second lighting signal generation unit 126 inverts the first lighting signal for a period when the lighting adjustment signal input from the lighting adjustment signal generation unit 125 is “1”. As a result, the ninth count of the basic clock that was “1”, that is, “lighted” in the first lighting signal becomes “0” indicating “off”. As a result, even during the period in which the period of the pixel clock is increased due to the phase shift, the lighting period of the light source device 281 is equivalent to 8 counts of the basic clock, which is the same lighting period as the pixel clock that is not phase-shifted.

  In other words, in FIG. 10A, the lighting adjustment signal generation unit 125 outputs a lighting adjustment signal indicating that the lighting state of the light source device 281 is designated as “off” for the ninth count of the basic clock of the third pixel clock. Output. Specifically, the lighting adjustment signal generator 125 indicates that the lighting state of the light source device 281 is reversed for the ninth clock of the basic clock that is part of the lighting period of the light source device 281 in the third pixel clock. Output a signal.

  In the example of FIG. 10A, since the period of the third pixel clock is increased by one basic clock by the phase shift, the lighting adjustment signal generation unit 125 transmits the status signal “SHIFT (+)”. The lighting state of the third pixel clock is inverted for one basic clock whose pixel clock period has changed due to the phase shift during the lighting period of the third pixel clock.

  Also, as shown in FIG. 10B, when “11” is output as the phase shift information in the second pixel clock, that is, information indicating that the next pixel clock is shortened by 1/8 basic clock, The phase shifter 121 outputs “SHIFT (−)” as the status signal in the third pixel clock, and sets the cycle of the pixel clock to 7 basic clocks.

  In this case, as shown in FIG. 10B, the lighting adjustment signal generation unit 125 is a signal indicating that the first lighting signal in the third pixel clock that is the current pixel clock is “1”, that is, “lighting”. If the pixel information indicating image on / off in the next pixel clock is “OFF” indicating “off”, the light source device 281 is lit only in the first count of the basic clock in the next pixel clock. “1” is output as the lighting adjustment signal in the next basic clock in which the clock count is 7, that is, in the first count clock of the next pixel clock.

  The second lighting signal generation unit 126 inverts the first lighting signal for a period when the lighting adjustment signal input from the lighting adjustment signal generation unit 125 is “1”. As a result, the first count of the basic clock that was “0”, that is, “off” in the first lighting signal in the next pixel clock becomes “1” indicating “lighting”. As a result, even during the period when the period of the pixel clock is shortened due to the phase shift, the lighting period of the light source device 281 is a total of 8 counts of the basic clock with the first basic clock of the next pixel clock, and the pixel clock that is not phase-shifted It becomes the same lighting period.

  Here, in the examples of FIGS. 9, 10A, and 10B, the lighting time is adjusted by inverting the pixel clock on the terminal side of the phase-softened pixel clock. It is also possible to perform this process (hereinafter referred to as “adjustment of the tip”). Such an example will be described with reference to FIGS. 11 and 12A and 12B.

  In FIG. 11, the lighting adjustment signal generation unit 125 according to the present embodiment outputs a lighting adjustment signal for adjusting the lighting time by inverting the first lighting signal at the leading end side of the phase-shifted pixel clock. It is a figure which shows the condition at the time. As shown in FIG. 11, in the case of tip adjustment, the lighting adjustment signal generation unit 125 is based on the phase shift information on the assumption that the status signal is “0”, that is, a pixel clock that is not phase-shifted. to decide.

  Since it is assumed that the lighting time is adjusted on the leading end side of the pixel clock, the determination is made before the pixel clock for adjusting the lighting time. Therefore, it is assumed that the next pixel clock is a lit pixel, that is, pixel information is “ON”. Further, if the current pixel clock is a lit pixel, it is sufficient to continue lighting without adjusting the lighting time. Therefore, the current pixel clock is a non-lit pixel, that is, the first lighting signal is “1”. It is assumed that.

  In such a case, when the phase shift information is “01”, that is, when the clock cycle is lengthened in the next pixel clock, the lighting adjustment signal generation unit 125 is when the clock count number is “8”. The lighting adjustment signal is output at the next basic clock. Further, when the phase shift information is “11”, that is, when the clock cycle is shortened in the next pixel clock, the lighting adjustment signal generation unit 125 performs the following basic operation when the clock count number is “7”. A lighting adjustment signal is output at the clock.

  The generation of the lighting adjustment signal in the case of such tip adjustment will be described with reference to FIGS. 12A shows a case where “01” is output as the phase shift information, and FIG. 12B shows each case in the optical writing device control unit 120 according to the present embodiment when “11” is output. It is a timing chart which shows a signal.

  As shown in FIG. 12A, when “01” is output as the phase shift information in the second pixel clock, that is, information indicating that the next pixel clock is lengthened by 1/8 basic clock, the phase shift is output. The unit 121 outputs “SHIFT (+)” as the status signal in the third pixel clock, and sets the cycle of the pixel clock to 9 basic clocks.

  In this case, as shown in FIG. 12A, the lighting adjustment signal generator 125 is a signal indicating that the first lighting signal is “0”, that is, “off” in the second pixel clock that is the current pixel clock. If the pixel information indicating lighting / extinguishing in the next pixel clock is “1”, that is, information indicating “lighting”, the light source device 281 is extinguished for the first count of the basic clock in the next pixel clock cycle. In addition, “1” is output as the lighting adjustment signal in the next basic clock in which the count number of the basic clock of the current pixel clock is 8.

  The second lighting signal generation unit 126 inverts the first lighting signal for a period when the lighting adjustment signal input from the lighting adjustment signal generation unit 125 is “1”. As a result, the first count of the basic clock that was “1”, that is, “lighted” in the first lighting signal becomes “0” indicating “light off”. As a result, even during the period in which the period of the pixel clock is increased due to the phase shift, the lighting period of the light source device 281 is equivalent to 8 counts of the basic clock, which is the same lighting period as the pixel clock that is not phase-shifted.

  Also, as shown in FIG. 12B, when “11” is output as the phase shift information in the second pixel clock, that is, information indicating that the next pixel clock is shortened by 1/8 basic clock, The phase shifter 121 outputs “SHIFT (−)” as the status signal in the third pixel clock, and sets the cycle of the pixel clock to 7 basic clocks.

  In this case, as shown in FIG. 12B, the lighting adjustment signal generator 125 is a signal indicating that the first lighting signal is “0”, that is, “off” in the second pixel clock that is the current pixel clock. In addition, if the pixel information indicating lighting / extinguishing in the next pixel clock is “1”, that is, information indicating “lighting”, in order to light the light source device 281 for the 8th basic clock count in the element pixel clock cycle, “1” is output as the lighting adjustment signal in the next basic clock in which the basic clock count of the current pixel clock is 7.

  The second lighting signal generation unit 126 inverts the first lighting signal for a period when the lighting adjustment signal input from the lighting adjustment signal generation unit 125 is “1”. As a result, the eighth count of the basic clock that was “0”, that is, “lights off” in the first lighting signal in the current pixel clock becomes “1” indicating “lighting”. As a result, even during the period when the period of the pixel clock is shortened due to the phase shift, the lighting period of the light source device 281 is a total of 8 counts of the basic clock with the last basic clock of the previous pixel clock, and the pixel clock that is not phase-shifted It becomes the same lighting period.

  As described above, even in the case of the tip adjustment for adjusting the turning on / off of the pixel on the tip side of the phase-shifted pixel clock, it is possible to obtain the same effect as in the case of the end adjustment. As shown in FIGS. 10A and 10B, in the case of termination adjustment, the lighting adjustment signal generator 125 indicates that the status signal is either “SHIFT (+)” or “SHIFT (−)”. The pixel clock, that is, the next pixel clock adjacent to the terminal side of the pixel clock by counting another signal in the phase-shifted pixel clock by one count of the basic clock on the terminal side of the phase-shifted pixel clock. The basic clock 1 count is adjusted.

  On the other hand, as shown in FIGS. 12A and 12B, in the case of tip adjustment, the lighting adjustment signal generation unit 125 has a pixel clock whose phase shift information is either “01” or “11”, that is, By determining another signal in the pixel clock before the phase-shifted pixel clock, it is adjacent to the leading end of the phase-shifted pixel clock or one count of the basic clock of the phase-shifted pixel clock. The basic clock 1 count of the previous pixel clock is adjusted.

  As described above, in the optical writing device 120 according to the present embodiment, the status signal indicating the phase shift state of the current pixel clock, the first lighting signal indicating the on / off state of the current pixel clock, and the phase of the next pixel clock. Based on the phase shift information indicating the shift state, the pixel information indicating the on / off state of the next pixel clock, and the count value of the basic clock, the phase shift is performed by one count of the basic clock at the front end or the end of the pixel clock. A signal for inverting the first lighting signal corresponding to one count of the basic clock adjacent to the leading edge or the trailing edge of the pixel clock is output.

  As a result, the lighting times of the phase-shifted pixel clock and the other pixel clocks can be made uniform without losing the number of basic clocks included in the original pixel clock, that is, without losing the resolution of one pixel clock. can do. Therefore, it is not necessary to include a configuration for randomly controlling the phase shift position for each main scanning line, and at the time of correcting the scanning speed unevenness in the optical writing device, it is possible to prevent the image quality from being lowered at a low cost.

  In the above embodiment, the case where the lighting adjustment signal generation unit 125 outputs a 1-bit lighting adjustment signal indicating only whether or not to invert the first lighting signal has been described as an example. Therefore, as shown in FIGS. 9 and 11, it is necessary to check the pixel information and the state of the first lighting signal to determine whether adjustment is necessary. On the other hand, if the lighting signal is a 2-bit signal that designates one of “not adjusting”, “forcibly lighting”, and “forcibly turning off” as the lighting adjustment signal, the judgment condition is Can be omitted.

  For example, in the case of FIG. 10A, by turning off the last basic clock of one phase-shifted third pixel clock for one clock, the lighting period of the phase-shifted third pixel clock is equivalent to eight clocks. It is an adjustment. In this case, if the signal output as the lighting adjustment signal is a signal indicating “forcibly turn off”, at least the third pixel clock may be in a lighting state or in a lighting state. Among the conditions shown in FIG. 9, the “first lighting signal” condition can be omitted.

  On the other hand, in the case of FIG. 12A, by turning off the first basic clock of one phase shifted third pixel clock for “one clock”, the lighting period of the phase shifted third pixel clock is equivalent to eight clocks. It is an adjustment. In this case, if the signal output as the lighting adjustment signal is a signal indicating “forcibly turn off”, at least the third pixel clock may be in a lighting state or in a lighting state. Among the conditions shown in FIG. 9, the “pixel information” condition can be omitted.

1 image forming apparatus,
10 CPU,
11 RAM,
12 ROM,
13 engine,
14 HDD,
15 I / F,
16 LCD,
17 Operation part,
18 Bus,
20 controller,
21 ADF,
22 Scanner unit,
23 Output tray,
24 display panels,
25 Paper feed table,
26 print engine,
27 Output tray,
28 Network I / F,
30 Main control unit,
31 engine control unit,
32 Input / output control unit,
33 Image processing unit,
34 Operation display control unit,
101 paper feed tray,
102 paper feed roller,
103 separation roller,
104 paper,
105 Conveyor belt,
106BK, 106C, 106M, 106Y Image forming unit,
107 driving roller,
108 driven roller,
109BK, 109C, 109M, 109Y photosensitive drum,
110BK charger,
111 optical writing device,
112BK, 112C, 112M, 112Y Developer,
113BK, 113C, 113M, 113Y
115BK, 115C, 115M, 115Y transfer device,
116 fixing device,
120 optical writing device controller,
121 phase shift unit,
122 phase shift information output unit,
123 image information acquisition unit,
124 first lighting signal generator,
125 lighting adjustment signal generator,
126 second lighting signal generator,
280 reflector,
281,281BK, 281Y, 281M, 281C Light source device,
282, 282BK, 282Y, 282M, 282C Mirror 283 Horizontal synchronization detection sensor

JP 2007-203739 A JP 2003- 211723 A Japanese Patent Laid-Open No. 8-238795

Claims (10)

An optical writing device that irradiates a light beam to form an electrostatic latent image on a photoreceptor,
A scanning line at a speed at which the light beam guided by a scanning unit that guides a light beam emitted from a light source for exposing the photosensitive member onto the photosensitive member and scans the photosensitive member scans the photosensitive member. A phase shift information acquisition unit that acquires phase shift information that is information for correcting unevenness in scanning speed, which is a change in the above,
A pixel clock indicating a timing of a pixel on the scan line is generated based on a basic clock, and the number of clocks of the basic clock included in at least one pixel clock in one main scan line among the generated pixel clocks is acquired. A phase shift unit that outputs a phase-shifted state signal indicating a phase-shifted state of the output pixel clock, and outputs a pixel clock that is phase-shifted by increasing or decreasing based on the phase-shifted information,
A pixel information acquisition unit that acquires pixel information, which is information of pixels constituting the image, according to the pixel clock, based on information on an image to be formed as the electrostatic latent image;
Based on the acquired pixel information, a first lighting signal output unit that outputs a first lighting signal for controlling a lighting state of a light source that emits the light beam according to the pixel clock;
Based on the phase shift state signal and the count number of the basic clock, the lighting period of the light source corresponding to the phase-shifted pixel clock is the same as the lighting period of the light source corresponding to the other pixel clocks. A lighting adjustment signal output unit for outputting a lighting adjustment signal for adjusting one lighting signal;
And a second lighting signal output unit that outputs a second lighting signal obtained by inverting a part of the first lighting signal based on the lighting adjustment signal.   The lighting adjustment signal output unit outputs the lighting adjustment signal indicating that a lighting state at a front end or an end of a lighting period of the light source corresponding to the phase-shifted pixel clock is designated. 2. The optical writing device according to 1.   The lighting adjustment signal output unit further refers to at least one of the pixel information and the first lighting signal, and inverts the lighting state in a part of the lighting period of the light source corresponding to the phase-shifted pixel clock. The optical writing device according to claim 1, wherein the lighting adjustment signal indicating that the lighting is performed is output.   The lighting adjustment signal output unit indicates that the lighting period of the light source corresponding to the phase-shifted pixel clock is inverted by a period corresponding to the basic clock number increased or decreased based on the phase shift information. 4. The optical writing device according to claim 3, wherein a lighting adjustment signal is output. The phase shift information acquisition unit acquires the phase shift information according to the pixel clock,
The phase shift unit outputs the phase shift state signal corresponding to the phase shift information acquired in the pixel clock one clock before by outputting the phase shift state signal according to the pixel clock,
The lighting adjustment signal output unit further outputs the lighting adjustment signal based on the phase shift state in the current pixel clock and the phase shift state in the next pixel clock by referring to the phase shift information. The optical writing device according to claim 1, wherein the optical writing device is an optical writing device. The pixel information acquisition unit outputs the first lighting signal for controlling the lighting state of the light source corresponding to the information of the pixel acquired in the pixel clock one clock before,
The lighting adjustment signal output unit further refers to the pixel information and the first lighting signal, based on the lighting state of the light source in the current pixel clock and the lighting state of the light source in the next pixel clock. 6. The optical writing device according to claim 1, wherein a lighting adjustment signal is output.   The lighting adjustment signal output unit, when the phase-shifted pixel clock is phase-shifted by reducing the number of clocks of the basic clock, the lighting period of the light source corresponding to the phase-shifted pixel clock The optical writing device according to claim 1, wherein the lighting adjustment signal indicating that the light source is turned on is output in a period adjacent to a leading end or a terminating end of the optical writing device.   The lighting adjustment signal output unit, when the phase-shifted pixel clock is phase-shifted by increasing the number of clocks of the basic clock, the lighting period of the light source corresponding to the phase-shifted pixel clock 8. The optical writing device according to claim 1, wherein the lighting adjustment signal indicating that the light source is turned off is output during a period of a leading edge or a trailing edge of the optical writing apparatus.   An image forming apparatus comprising the optical writing device according to claim 1. A method of controlling an optical writing device that irradiates a light beam to form an electrostatic latent image on a photoreceptor,
A scanning line at a speed at which the light beam guided by a scanning unit that guides a light beam emitted from a light source for exposing the photosensitive member onto the photosensitive member and scans the photosensitive member scans the photosensitive member. Obtain phase shift information, which is information for correcting unevenness in scanning speed, which is a change in the above,
Generating a pixel clock indicating pixel timing on the scan line based on a basic clock;
The phase-shifted pixel clock is output by increasing or decreasing the number of clocks of the basic clock included in at least one pixel clock in one main scanning line among the generated pixel clocks based on the acquired phase shift information. And a phase shift state signal indicating the phase shift state of the output pixel clock,
Based on the information of the image to be formed as the electrostatic latent image, pixel information that is information of pixels constituting the image is acquired according to the pixel clock,
Based on the acquired pixel information, a first lighting signal for controlling a lighting state of a light source that emits the light beam is output according to the pixel clock,
Based on the phase shift state signal and the count number of the basic clock, the lighting period of the light source corresponding to the phase-shifted pixel clock is the same as the lighting period of the light source corresponding to the other pixel clocks. Output a lighting adjustment signal that adjusts one lighting signal,
A control method for an optical writing device, comprising: outputting a second lighting signal obtained by inverting a part of the first lighting signal based on the lighting adjustment signal.

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