JP2011064803A - Optical writing device and positional deviation correcting method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten a period required for an adjustment processing of adjusting the positions of an image in a main scanning direction and in a sub-scanning direction. <P>SOLUTION: The light amount of a light emitting element of a pattern detecting sensor 117 can be adjusted at a first timing before starting to form a positional deviation correction pattern and a second timing being a period for removing the toner on a conveying belt 105 by a belt cleaner 118 after the trailing end of the positional deviation correction pattern is detected by a sensor control unit 123. It is determined whether to perform the light amount adjusting operation at either of the first timing or the second timing. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical writing device and an optical writing device misregistration correction method, and more particularly to shortening the startup time of the optical writing device.

  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 such an electrophotographic image forming apparatus, by aligning the timing of forming an electrostatic latent image by exposing the photosensitive member and the timing of transporting the paper, an image is formed in the correct range of the paper. Adjustments are made. In addition, in a tandem image forming apparatus that forms a color image using a plurality of photoconductors, the exposure timing of each color photoconductor is adjusted so that the images developed on the photoconductors of each color are accurately superimposed. (For example, refer to Patent Document 1). Hereinafter, these adjustment processes are collectively referred to as misalignment correction.

  In the misregistration correction as disclosed in Patent Document 1, a timing detection pattern is formed by the same operation as a normal operation such as exposure of a photosensitive member and development of an electrostatic latent image, thereby reflecting light reflection type light. The period from the start of exposure of the photosensitive member to the reading of the timing detection image pattern is counted by the sensor. And the adjustment process is performed based on the difference between the counted period and the reference value by comparing the period thus counted with a predetermined reference value.

  The above-described misregistration correction is executed when the image forming apparatus is powered on, returned from the power saving state, or before executing the image forming output. The period required for this misalignment correction is, for example, about 10 to 20 seconds, and the user needs to wait for this period. In other words, the period of the positional deviation correction is a downtime for the user, and it is desired to shorten it.

  Here, when performing the positional deviation correction, an operation for confirming the irradiation light amount of the light emitting element included in the optical sensor for reading the timing detection pattern is performed. In the operation for confirming the amount of irradiation light, the light emitting element included in the optical sensor irradiates a white surface on which nothing is drawn, the light receiving element included in the optical sensor detects the reflected light, and the detection signal Is determined based on whether or not the signal intensity is within a predetermined range.

  This operation for confirming the amount of irradiation light is executed on the assumption that the irradiation target is a white background. However, there is a possibility that the paper conveyance belt and the intermediate transfer belt, which are general irradiation targets, have fine scratches and dirt, and the reflected light when irradiated with the scratches and dirt is different from the reflected light on the white ground. . Therefore, in the operation for confirming the amount of irradiation light, a certain number of samplings are required in order to exclude the reflected light from the scratches and dirt described above. That is, it is necessary to irradiate the target surface many times and store the detection signal of the reflected light, and to exclude a value whose signal intensity is extremely different from many other signal intensities.

  For this reason, the operation for confirming the amount of irradiation light requires a period of about 2 seconds, for example, and is a process that needs to be executed first in the positional deviation correction. It has become. Although it is conceivable to shorten the misalignment correction period by canceling the operation for confirming the irradiation light amount, since the irradiation light amount of the light emitting element is not confirmed, the reliability of the misalignment correction is lowered.

  In addition, when the timing detection pattern detection fails in the above-described misalignment correction, if the light amount is not adjusted, a defect occurs on either the pattern image forming side or the pattern detecting side. Cannot judge whether

  The present invention has been made in view of the above circumstances, and shortens the time required for adjustment processing for adjusting the position of the image in the main scanning direction and the sub-scanning direction in the optical writing device mounted on the image forming apparatus. The purpose is to do.

  In order to solve the above problems, according to one embodiment of the present invention, a light source that irradiates a plurality of photoconductors arranged in the sub-scanning direction is controlled to irradiate the light beam, and the photoconductor is statically placed on the photoconductor. An image transferred to the surface of the carrier based on an output signal of a light source control unit that forms an electrostatic latent image and a sensor that images the surface of the carrier to which the image developed on the photoconductor is transferred. An image detection unit that detects that a position facing the sensor has been reached, and a period from when the light source control unit starts drawing a predetermined pattern until the image detection unit detects the pattern conveyed by the conveyance body A detection period counting unit that counts a detection period that is a period of time, and a reference period value from when the light source control unit starts drawing the pattern to when the image detection unit detects the predetermined pattern. A group A correction value calculating unit that calculates a correction value for correcting the timing of irradiating the light source with the light beam based on a difference between the value and the counted detection period; and removing the developer on the carrier. When executing the developer removal unit and the correction operation from when the pattern is drawn to when the correction value is calculated, the light amount of the light emitting unit that irradiates the surface of the carrier in the sensor is set to the surface of the carrier. A light amount adjustment unit that performs a light amount adjustment operation that adjusts based on a signal corresponding to the amount of reflected light by the light source, and the light amount adjustment unit includes a first light source controller before the light source control unit starts drawing the pattern. After the timing and the light source control unit completes the control of the light source for drawing the pattern, and the arrival determination unit detects that the end of the pattern has reached the predetermined position, The light amount adjustment operation can be executed at a second timing that is a period for allowing the developer removing unit to remove the developer on the transport body, and at any one of the first timing and the second timing, It is characterized by determining whether or not to perform the light amount adjustment operation.

  Here, when the light amount adjustment unit executes the light amount adjustment operation at the second timing, the light amount of the light emitting unit after the light amount adjustment operation and the light amount of the light emitting unit applied in the correction operation The light quantity comparison unit further compares a light quantity of the light emitting part after the light quantity adjustment operation and a light quantity of the light emitting part applied in the correction operation is a predetermined value or more. In some cases, it is preferable to instruct execution of the correction operation again.

  In addition, the light amount adjustment unit can determine whether the light amount adjustment operation is to be executed at the first timing or the second timing based on the execution timing of the correction operation.

  In addition, the light amount adjustment unit is configured to perform the first correction operation based on a temperature of a fixing device included in the image forming apparatus when the correction operation is performed during warm-up of the image forming apparatus in which the optical writing device is mounted. It is possible to determine whether the light amount adjustment operation is to be executed at any of the above timing and the second timing.

  Further, the light amount adjusting unit can execute the light amount adjusting operation at the first timing when the temperature of the fixing device is equal to or lower than a predetermined value.

  The light amount adjustment unit may execute the light amount adjustment operation at the first timing when the correction operation is executed after image formation output of an image forming apparatus in which the optical writing device is mounted. it can.

  The image forming apparatus further includes an in-machine temperature storage unit that stores an in-machine temperature of the image forming apparatus in which the optical writing device is mounted, and the light amount adjustment unit is configured to perform the image formation when the correction operation is performed. Based on the difference between the in-machine temperature of the apparatus and the in-machine temperature stored in the in-machine temperature storage unit, it is possible to determine at which of the first timing and the second timing the light amount adjustment operation is to be executed.

  Further, the light amount adjustment unit is configured to perform the first operation when a difference between an in-machine temperature of the image forming apparatus and an in-machine temperature stored in the in-machine temperature storage unit is greater than or equal to a predetermined value when the correction operation is performed. The light quantity adjustment operation can be executed at the timing of.

  The light amount adjustment unit may execute the light amount adjustment operation at the second timing when the correction operation is executed before the image formation output of the image forming apparatus on which the optical writing device is mounted. it can.

  The light amount adjustment unit performs the light amount adjustment operation at the second timing when the image forming output of the image forming apparatus on which the optical writing device is mounted is interrupted and the correction operation is performed. be able to.

  Further, the light amount adjustment unit can execute the light amount adjustment operation at the first timing when the correction operation is instructed by a user.

  According to another aspect of the present invention, an electrostatic latent image is formed on the photoconductor by controlling a light source that irradiates a light beam to a plurality of photoconductors arranged in the sub-scanning direction. A position at which the image transferred to the surface of the carrier is opposed to the sensor based on an output signal of a sensor that images the surface of the carrier to which the developed image is transferred onto the photosensitive member An image detection unit that detects that the image has reached the position, and a detection period from when the light source control unit starts drawing a predetermined pattern to when the image detection unit detects the pattern conveyed by the conveyance body A detection period counting unit that counts a period; a reference value that is a reference period value from when the light source control unit starts drawing the pattern until the image detection unit detects the predetermined pattern; and count A correction value calculation unit that calculates a correction value for correcting the timing of irradiating the light source with the light beam based on a difference from the detected detection period, and a developer removal that removes the developer on the carrier And the amount of light emitted from the light emitting unit that irradiates the surface of the carrier in the sensor when the correction operation is performed from when the pattern is drawn to when the correction value is calculated. And a light amount adjustment unit that performs a light amount adjustment operation for performing adjustment based on a signal corresponding to the light amount, wherein the light amount adjustment unit is configured to draw the pattern by the light source control unit. The first timing before the start and the light source control unit completes the control of the light source for drawing the pattern, and the arrival determination unit confirms that the end of the pattern has reached the predetermined position. , It is determined whether the light amount adjustment operation is to be executed at a second timing which is a period for causing the developer removing unit to remove the developer on the carrier. The light amount adjustment operation is executed at a predetermined timing.

  According to the present invention, it is possible to shorten the period required for the adjustment processing for adjusting the position of the image in the main scanning direction and the sub-scanning direction in the optical writing device mounted on the image forming apparatus.

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 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 information memorize | stored in the reference value memory | storage part which concerns on embodiment of this invention. It is a figure which shows the example of the pattern drawn in the position shift correction operation | movement which concerns on embodiment of this invention. It is a flowchart which shows the position shift correction operation | movement which concerns on embodiment of this invention. It is a figure which shows the information of the judgment reference | standard of the light quantity adjustment timing which concerns on embodiment of this invention. It is a figure which shows the timing of the process of position shift correction operation | movement based on embodiment of this invention and a prior art. It is a figure which shows the structure of the print engine 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, an image forming apparatus as an MFP (Multi Function Peripheral) will be described as an example. The image forming apparatus according to the present embodiment is an electrophotographic image forming apparatus, and the timing for completing the correction of the image writing position in the optical writing apparatus for forming an electrostatic latent image on the photosensitive member is advanced. It is a gist.

  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) 110, 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. A document on which an image has been formed by the print engine 26 is discharged to a discharge tray 27.

  When the image forming apparatus 1 operates as a scanner, the operation display control unit 34 or the input / output unit is operated in accordance with a user operation on the display panel 24 or a scan execution instruction input from an external PC or the like via the network I / F 28. The control unit 32 transfers a scan execution signal to the main control unit 30. The main control unit 30 controls the engine control unit 31 based on the received scan execution signal.

  The engine control unit 31 drives the ADF 21 and conveys the document to be imaged set on the ADF 21 to the scanner unit 22. Further, the engine control unit 31 drives the scanner unit 22 and images a document conveyed from the ADF 21. If no original is set on the ADF 21 and the original is directly set on the scanner unit 22, the scanner unit 22 takes an image of the set original under the control of the engine control unit 31. That is, the scanner unit 22 operates as an imaging unit.

  In the imaging operation, an imaging element such as a CCD included in the scanner unit 22 optically scans the document, and imaging information generated based on the optical information is generated. The engine control unit 31 transfers the imaging information generated by the scanner unit 22 to the image processing unit 33. The image processing unit 33 generates image information based on the imaging information received from the engine control unit 31 according to the control of the main control unit 30. Image information generated by the image processing unit 33 is stored in a storage medium attached to the image forming apparatus 1 such as the HDD 40. That is, the scanner unit 22, the engine control unit 31, and the image processing unit 33 work together to function as a document reading unit.

  The image information generated by the image processing unit 33 is stored in the HDD 40 or the like as it is according to a user instruction or transmitted to an external device via the input / output control unit 32 and the network I / F 28. That is, the ADF 21 and the engine control unit 31 function as an image input unit.

  Further, when the image forming apparatus 1 operates as a copying machine, the image processing unit 33 generates drawing information 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. To do. 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 transport belt 105 that transports the paper (recording paper) 104 separated and fed by the paper feed roller 102 and the separation roller 103 from the paper feed tray 101, the transport belt 105 is sequentially transported from the upstream side in the transport direction. A plurality of image forming units (electrophotographic process units) 106BK, 106M, 106C, and 106Y are arranged.

  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 the 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.

  In such an image forming apparatus 1, errors in the interaxial distances of the photosensitive drums 109 BK, 109 M, 109 C, and 109 Y, parallelism errors in the photosensitive drums 109 BK, 109 M, 109 C, and 109 Y, and deflection in the optical writing device 111. The toner images of each color do not overlap at positions that should originally overlap due to errors in the installation of mirrors, writing timing errors of electrostatic latent images on the photosensitive drums 109BK, 109M, 109C, and 109Y. May occur.

  For the same reason, the image may be transferred to a range that is outside the range where the image is originally transferred on the paper to be transferred. As such misregistration components, skew, sub-scan registration error, magnification error in the main scanning direction, registration error in the main scanning direction, and the like are mainly known. Further, the expansion and contraction of the conveyor belt due to the temperature change in the apparatus and deterioration with the passage of time are known.

  A pattern detection sensor 117 is provided to correct such positional deviation. The pattern detection sensor 117 is an optical sensor for reading a misregistration correction pattern transferred onto the conveyance belt 105 by the photosensitive drums 109BK, 109M, 109C, and 109Y, and is used for correction drawn on the surface of the conveyance belt 105. A light emitting element for irradiating the pattern and a light receiving element for receiving reflected light from the correction pattern are included. As shown in FIG. 3, the pattern detection sensor 117 is supported on the same substrate along the direction orthogonal to the conveyance direction of the conveyance belt 105 on the downstream side of the photosensitive drums 109BK, 109M, 109C, and 109Y. . The details of the pattern detection sensor 117 and the mode of positional deviation correction will be described in detail later.

  A belt cleaner 118 is provided in order to remove the toner of the pattern drawn on the conveyance belt 105 and prevent the sheet conveyed by the conveyance belt 105 from becoming dirty in such misalignment correction. As shown in FIG. 3, the belt cleaner 118 is a cleaning blade pressed against the conveyance belt 105 on the downstream side of the pattern detection sensor 117 and on the upstream side of the photosensitive drum 109, and the surface of the conveyance belt 105. And a developer remover that scrapes off the toner adhering to the toner.

  Furthermore, the belt cleaner 118 according to the present embodiment includes a function of collecting toner adhering to the conveyance belt 105 by applying a bias voltage. By applying a bias voltage having a polarity opposite to the charge of the toner, the toner adhering to the conveyance belt 105 can be peeled off and adsorbed to the belt cleaner 118.

  Note that when the toner charge is mixed in positive and negative, the belt cleaner 118 vibrates the bias voltage positively and negatively. As a result, toner having either positive or negative charge can be peeled off from the conveying belt 105 and adsorbed to the belt cleaner 118.

  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 to be written 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 the 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 282) by an optical system such as an fθ lens (not shown), and further, the photosensitive drums 109BK, 109M, and 109C are further advanced by the optical system. , 109Y is scanned.

  The reflecting mirror 280 is a hexahedral polygon mirror, and can rotate by scanning the laser beam corresponding to the line in the main scanning direction 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.

  Next, a control block of the optical writing device 111 according to the present embodiment will be described with reference to FIG. FIG. 6 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 between the light source device 281, the horizontal synchronization detection sensor 283, and the pattern detection sensor 117. .

  As shown in FIG. 6, the optical writing device control unit 120 according to the present embodiment includes a writing control unit 121, a counting unit 122, a sensor control unit 123, a correction value calculation unit 124, a reference value storage unit 125, and a correction value storage unit. 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, a control program stored in the ROM 12 or the HDD 14 is loaded into the RAM 11 and is operated under the control of the CPU 10.

  The writing control unit 121 is a light source control unit that controls the light source device 281 in accordance with a synchronization detection signal from the horizontal synchronization detection sensor 283 based on image information input from the engine control unit 31 of the controller 20. In addition to driving the light source device 281 based on the image information input from the engine control unit 31, the write control unit 121 also draws a pattern for correcting misalignment in the misalignment correction process described above. 281 is driven. The correction value generated as a result of this misalignment correction processing is stored in the correction value storage unit 126 shown in FIG. 6, and the writing control unit 121 uses the light source based on the correction value stored in this correction value storage unit 126. The timing for driving the device 281 is corrected.

  Further, the writing control unit 121 includes a function of acquiring a detection signal from the horizontal synchronization detection sensor 283 and performing synchronization with the rotation of the reflecting mirror 280 as described with reference to FIG. Further, when the electrostatic latent image formed on the photosensitive drum 109 is developed with toner as a developer, the writing control unit 121 and the photosensitive drums 109BK, 109M, 109C, and 109Y and the developing units 112BK and 112M are developed. , 112C, 112Y also functions as a voltage control unit that controls the voltage applied between them.

  In the misregistration correction process, the count unit 122 starts counting at the same time as the writing control unit 121 controls the light source device 281 to start exposure of the photosensitive drum 109BK. The count unit 122 stops counting when the sensor control unit 123 detects the pattern based on the output signal of the pattern detection sensor 117. As a result, in the above-described misregistration correction processing, the count unit 122 controls the light source device 281 to start the exposure of the photosensitive drum 109BK in the above-described misregistration correction process. It functions as a detection period counting unit that counts the detection period until a pattern is detected. Hereinafter, this count value is referred to as a write start count value. Further, the count unit 122 counts the detection timings of the continuously drawn patterns in the positional deviation correction process for correcting the deviation of the toner images of the respective colors. Hereinafter, this count value is referred to as a drum interval count value.

  The sensor control unit 123 is a control unit that controls the pattern detection sensor 117. As described above, the misregistration correction pattern formed on the conveyance belt 105 is subjected to pattern detection based on the output signal of the pattern detection sensor 117. It is an arrival determination unit that determines that the position of the sensor 117 has been reached. When the sensor control unit 123 determines that the position deviation correction pattern has reached the position of the pattern detection sensor 117 as described above, the sensor control unit 123 inputs a detection signal to the count unit 122. That is, the sensor control unit 123 functions as an image detection unit.

  The sensor control unit 123 includes a function of controlling the pattern detection sensor 117 and adjusting the light amount of the light emitting elements included in the pattern detection sensor 117. That is, the sensor control unit 123 also functions as a light amount adjustment unit. When adjusting the light amount of the light emitting element, the sensor control unit 123 drives the light emitting element with a predetermined power, and irradiates the white background of the conveyance belt 105 on which nothing is drawn. And based on the value of the output signal of the light receiving element which received the reflected light, the irradiation light quantity of the light emitting element is judged and adjusted.

  For example, if the output signal of the light receiving element is lower than a predetermined target value, the sensor control unit 123 performs the same process again after increasing the driving power of the light emitting element. On the other hand, if the output signal of the light receiving element is higher than a predetermined target value, the sensor control unit 123 performs the same process again after increasing the driving power of the light emitting element. By repeating such processing, the sensor control unit 123 adjusts the driving power of the light emitting element so that the driving power of the light emitting element becomes a target value, and as a result, the irradiation light amount of the light emitting element is adjusted to an appropriate level. The

  By adjusting the amount of light reflected from the conveyor belt 105 to a predetermined target value, the S / N ratio by the light receiving element is improved, and the pattern of the misalignment correction mark 400 can be detected with high accuracy. This light amount adjustment process is executed during the misalignment correction process, and the gist of the present embodiment is to change the specific timing.

  The correction value calculation unit 124 calculates a correction value based on the reference value stored in the reference value storage unit 125 based on the count result by the counting unit 122. That is, the correction value calculation unit 124 functions as a reference value acquisition unit and a correction value calculation unit. FIG. 7 shows an example of reference values stored in the reference value storage unit 125. As shown in FIG. 7, the reference value storage unit 125 stores a writing start timing reference value and a drum interval reference value.

  The write start timing reference value is a period from when the write control unit 121 controls the light source device 281 to start exposure of the photosensitive drum 109BK to when the pattern detection sensor 117 detects a pattern for correcting misalignment. Is the reference value. That is, the correction value calculation unit 124 compares the write start count value with the write start timing reference value among the count values by the count unit 122, and calculates a correction value based on the difference between the two.

  The drum interval reference value is a reference value of the detection timing for each of the continuously drawn patterns as described above. That is, the correction value calculation unit 124 compares the drum interval count value with the drum interval reference value among the count values of the counting unit 122, and calculates a correction value based on the difference between the two. The correction value calculated in this way is stored in the correction value storage unit 126 as described above. Thus, by storing the correction value in the correction value storage unit 126, the writing control unit 121 can drive the light source device 281 with reference to the correction value.

  In addition to the functional configuration shown in FIG. 6, the optical writing device control unit 120 according to the present embodiment has a function of controlling the driving roller 107 that rotates the conveyor belt 105 and a function of controlling the belt cleaner 118.

  Next, the misregistration correction operation according to the present embodiment will be described with reference to FIG. FIG. 8 is a diagram showing marks (hereinafter referred to as misalignment correction marks) drawn on the transport belt 105 by the light source device 281 controlled by the writing control unit 121 in the misalignment correction operation according to the present embodiment. It is. As shown in FIG. 8, the misregistration correction mark 400 according to this embodiment includes a plurality of misregistration correction pattern rows 401 in which various patterns are arranged in the sub-scanning direction (this embodiment). 3) are arranged side by side. In FIG. 8, the solid line represents the pattern drawn by the photosensitive drum 109BK, the dotted line represents the photosensitive drum 109Y, the broken line represents the photosensitive drum 109C, and the alternate long and short dash line represents the pattern drawn by the photosensitive drum 109M.

  As shown in FIG. 8, the pattern detection sensor 117 has a plurality (three in the present embodiment) of sensor elements 170 in the main scanning direction, and each misalignment correction pattern row 401 includes each sensor element. It is drawn at a position corresponding to 170. Thereby, the optical writing control unit 120 can detect the pattern at a plurality of positions in the main scanning direction, and can improve the accuracy of the misregistration correction operation by calculating the average value of each.

  As illustrated in FIG. 8, the misalignment correction pattern row 401 includes a start position correction pattern 411 and a drum interval correction pattern 412. As shown in FIG. 8, the drum interval correction pattern 412 is repeatedly drawn. The start position correction pattern 411 is a pattern drawn in order to count the write start count value described above. The start position correction pattern 411 is also used for correcting the detection timing when the sensor control unit 123 detects the drum interval correction pattern 412.

  As shown in FIG. 8, the start position correction pattern 411 according to this embodiment is a line drawn by the photosensitive drum 109BK and parallel to the main scanning direction. In the start position correction using the start position correction pattern 411, the optical writing device control unit 120 performs a write start timing correction operation based on the read signal of the start position correction pattern 411 by the pattern detection sensor 117. In other words, the writing start timing reference value stored in the reference value storage unit 125 is the same as the drawn black after the light source device 281 starts drawing the black pattern on the photosensitive drum 109BK in the start position correction pattern 411. This value is a reference value for the period until the pattern is read by the pattern detection sensor 117 and detected by the sensor control unit 123.

  As the name suggests, the drum interval correction pattern 412 is a pattern drawn to count the drum interval count value described above. As shown in FIG. 8, the drum interval correction pattern 412 includes a sub-scanning direction correction pattern 413 and a main scanning direction correction pattern 414. The optical writing device control unit 120 corrects the positional deviation in the sub-scanning direction of each of the photosensitive drums 109BK, 109M, 109C, and 109Y based on the reading signal of the sub-scanning direction correction pattern 413 by the pattern detection sensor 117. Based on the read signal of the scanning direction correction pattern 414, the positional deviation correction of each photosensitive drum in the main scanning direction is performed.

  That is, the drum interval reference value stored in the reference value storage unit 125 is the drum interval correction value that is drawn after the light source device 281 starts drawing the drum interval correction pattern 412 under the control of the writing control unit 121. Each line included in the pattern 412 for use is a value serving as a reference for a period until the line is read by the pattern detection sensor 117 and detected by the sensor control unit 123.

  When the positional deviation correction using the positional deviation correction mark 400 as shown in FIG. 8 is executed and completed, the optical writing device control unit 120 controls the driving roller 107 to continue the rotation of the conveying belt 105, and The bias voltage of the belt cleaner 118 is controlled to clean the conveying belt 105. As a result, the toner adhering to the conveyance belt 105 is removed by the positional deviation correction, and the conveyance belt 105 is cleaned, so that the toner adheres to the back surface of the sheet conveyed by the conveyance belt 105 and the sheet becomes dirty. Can be prevented.

  This cleaning process is generally executed for a period of about 3 seconds. That is, the optical writing device control unit 120 controls the driving roller 107 for 3 seconds after the sensor control unit 123 detects the last pattern included in the misregistration correction mark 400 in the misregistration correction described above. Continue to rotate the belt 105. During this period, control such as oscillating the bias voltage of the belt cleaner 118 positively or negatively is performed, and the toner adhering to the conveying belt 105 is peeled off.

  One of the gist of the present embodiment is to adjust the light amount of the light emitting elements included in the pattern detection sensor 117 in the cleaning process for about 3 seconds. Since this light amount adjustment is generally executed for about 2 seconds, it can be completed during the cleaning process executed for about 3 seconds, and the period until the positional deviation correction is completed can be shortened.

  When the charge of the toner is only one of positive and negative, the vibration of the bias voltage is not necessary. In this case, the optical writing device control unit 120 applies a bias voltage having a charge opposite to the charge of the toner, and peels off the toner attached on the transport belt 105. Also, the bias voltage of the belt cleaner 118 may be applied during normal operation. In this case, the optical writing device control unit 120 only controls the driving roller 107 to continue the conveyance belt 105 without changing the control during the cleaning process.

  Further, it is possible to employ a mechanism in which the toner adsorbed by the belt cleaner 118 is returned to the conveying belt 105 again and collected by a separately provided toner collecting unit during the cleaning period. In this case, during the cleaning process, the optical writing control unit 120 controls the bias voltage of the belt cleaner 118 and returns the toner collected on the belt cleaner 118 side to the conveying belt 105 side again. Then, similar to the belt cleaner 118, the toner is collected by a toner collecting unit provided facing the conveying belt 105.

  This toner recovery unit can be configured to only scrape the toner, such as the above-described cleaning blade, or to apply both a bias voltage to peel the toner from the conveyor belt 105, and both. The structure to employ | adopt may be sufficient.

  In such an aspect of the image forming apparatus 1 and the misregistration correction operation, the gist of the present embodiment is that the position required by starting the misregistration correction operation is shortened by shortening the period required to start the misregistration correction operation. It is to shorten the downtime for the user by advancing the completion timing of the deviation correction operation. Therefore, the optical writing device control unit 120 according to the present embodiment changes the timing for executing the light amount adjustment of the light emitting elements of the pattern detection sensor 117 described above. Hereinafter, the misregistration correction operation according to the present embodiment will be described with reference to FIG.

  FIG. 9 is a flowchart showing the misalignment correction operation according to this embodiment. When the misregistration correction operation is started, first, the sensor control unit 123 determines whether or not to perform light amount adjustment in advance based on a trigger for executing the misregistration correction operation (S901). FIG. 10 shows items to be determined by the sensor control unit 123 in S901.

  FIG. 10 is a diagram illustrating information on items to be determined by the sensor control unit 123 in S901. The information shown in FIG. 10 is held inside the sensor control unit 123, and the sensor control unit 123 makes a determination in S901 by referring to this information. As shown in FIG. 10, the sensor control unit 123 is one of the determination target items, that is, misalignment correction when the image forming apparatus 1 is warmed up, and the temperature of the fixing device 116 at the start of misalignment correction is 100. Judge whether it is less than ℃.

  This is because the fixing device 116 is heated when the image forming apparatus 1 is warmed up. However, when heating is performed from a temperature lower than 100 ° C., a long time is required for the heating. Accordingly, even if the time required for correcting the misregistration is shortened, the image forming output cannot be executed until the heating of the fixing device 116 is completed. Therefore, the sensor control unit 123 performs more reliable prior light amount adjustment. Judge that it should be done.

  Further, the sensor control unit 123 determines whether or not the operation is a misregistration correction operation after the print job is completed. This is because the image formation output has already been completed in the misregistration correction operation after the end of the print job, so even if the completion timing of the misregistration correction operation is delayed, there is no downtime for the user. Therefore, the sensor control unit 123 determines that a more reliable prior light amount adjustment should be executed.

  Further, the sensor control unit 123 determines whether or not the in-machine temperature has changed by 10 ° C. or more from the previous positional deviation correction. This is because the expansion and contraction of the conveying belt 105 and the expansion of the driving roller 107 and the driven roller 108 may occur due to the change in the temperature inside the apparatus, and the conveying timing and conveying speed of the conveying belt 105 with respect to the photosensitive drum 109 may change. Therefore, it is desired to perform more accurate positional deviation correction. Accordingly, the sensor control unit 123 determines that the more reliable prior light amount adjustment should be executed.

  Further, the sensor control unit 123 determines whether or not the current misalignment correction is a process instructed by the user. In the misalignment correction operation instructed by the user, the reliability of the misalignment correction result has priority over the downtime of the apparatus. Therefore, the sensor control unit 123 determines that a more reliable prior light amount adjustment should be executed.

  On the other hand, for example, the sensor control unit 123 determines whether or not the current misregistration correction is a misregistration correction before execution of a print job, that is, image formation output, as a determination criterion when the light amount adjustment is performed after the misalignment correction. Or whether or not the positional deviation correction is being executed. This is considered that the user is waiting for the output of the printed paper in the positional deviation correction before or during execution of the print job. Therefore, the sensor control unit 123 determines that the subsequent light amount adjustment with a short downtime should be executed.

  The sensor control unit 123 according to the present embodiment first determines a determination criterion (hereinafter, referred to as a precondition) when performing light amount adjustment in advance, and executes a prior light amount adjustment when any one of them applies. . As a result, when high reliability is required by the misregistration correction, the misregistration correction in advance is executed, and a high-quality image forming output that is the original purpose of the image forming apparatus can be guaranteed.

  On the other hand, none of the determination criteria for adjusting the light amount in advance applies, and if any one of the determination criteria for adjusting the light amount afterwards (hereinafter referred to as a postcondition) applies, the sensor control unit 123 Execute post light adjustment. Thereby, the start timing of misalignment correction can be advanced and the down timing for the user can be shortened.

  In addition to such an aspect, for example, the post-conditions may be determined first, and if any one of them applies, the post-light amount adjustment may be executed. Thereby, a user's downtime can be shortened more. Such an aspect is particularly effective when, for example, the number of years after manufacture is relatively short and the components constituting the light emitting element of the pattern detection sensor 117 and the conveyor belt 105 are not deteriorated.

  In addition, it is possible to determine each of the precondition and the postcondition, and apply the one having the larger number. Note that the determination criteria shown in FIG. 10 are merely examples, and even if other than the determination criteria shown in FIG. 10, it is recommended that the light amount adjustment be performed in advance, or the processing period even if the light amount adjustment is omitted. It is possible to determine that the light amount adjustment should be performed in advance by determining the case where it does not lead to shortening of the image or the case where the downtime for the user does not occur even if the light amount adjustment is performed. Further, the light amount should be adjusted afterwards by determining when downtime for the user becomes more problematic or when the accuracy of positional deviation correction is not greatly reduced even after the subsequent light amount adjustment. Can be judged.

  As a result of determining the timing of light amount adjustment based on the items as shown in FIG. 10, when it is determined that the timing is advance (S901 / YES), the sensor control unit 123 performs the light amount adjustment in the above-described manner. This is performed (S902). When the light amount adjustment is completed, the writing control unit 121 drives the light source device 281 to start drawing the misregistration correction mark 400 shown in FIG. 8, and the counting unit 122 starts counting (S903).

  When the start position correction pattern 411 that is the first pattern reaches the detection position of the pattern detection sensor 117 after the image formation of the misregistration correction mark 400 is started in S903, the sensor control unit 123 causes the pattern detection sensor 117 to start. The start position correction pattern is detected based on the output signal (S904).

  When the sensor control unit 123 detects the start position correction pattern 411, the count unit 122 acquires the above-described count value based on the detection result (S905) and inputs it to the correction value calculation unit 124. In S <b> 905, the count unit 122 acquires the count value for each of the plurality of sensor elements 170 and inputs the count value to the correction value calculation unit 124.

  When the correction value calculation unit 124 acquires a plurality of count values from the count unit 122, the correction value calculation unit 124 obtains an average value thereof (S906), calculates a correction value based on the average value and the reference value described above, and stores the correction value. The information is stored in the unit 126 (S907). When the correction value is stored in the correction value storage unit 126, the optical writing device control unit 120 performs the cleaning process as described above in order to remove the toner of the misregistration correction mark 400 drawn on the transport belt 105. Is executed (S908), and the process is terminated.

  On the other hand, as a result of determining the timing of light amount adjustment based on the items as shown in FIG. 10, if it is determined that the timing is later (S901 / NO), the sensor control unit 123 does not perform the light amount adjustment. The drive voltage of the light emitting element included in the pattern detection sensor 117 is set to a preset reference value. Then, similarly to S903, the writing control unit 121 drives the light source device 281 to start drawing the misregistration correction mark 400 shown in FIG. 8, and the counting unit 122 starts counting (S910). The processing is executed in the same manner as the subsequent S904 to S907 (S911 to S914).

  When the correction value is stored in the correction value storage unit 126 by the process of S914, the optical writing device control unit 120 is configured to remove the toner of the misregistration correction mark 400 drawn on the transport belt 105 as described above. The cleaning process as described above is executed. And the sensor control part 123 performs light quantity adjustment by the aspect mentioned above using the period of this cleaning process (S915).

  When the light amount adjustment is completed during the cleaning process period, the sensor control unit 123 adjusts the driving current of the light emitting element applied in the processes of S910 to S914, that is, the predetermined reference value and the light amount adjustment process of S915. The drive current of the subsequent light emitting element is compared (S916). That is, the sensor control unit 123 functions as a light amount comparison unit. As a result of the determination in S916, when the difference between the two is within a predetermined value (S916 / YES), the sensor control unit 123 determines that the light amount of the light emitting element in the positional deviation correction executed in S910 to S914 is within an appropriate range. Therefore, it is determined that the result of the positional deviation correction is appropriate, and the process is terminated.

  On the other hand, as a result of the determination in S916, if the difference between the two exceeds a predetermined value (S916 / NO), the sensor control unit 123 determines that the light amount of the light emitting element in the misalignment correction executed in S910 to S914 is incorrect. It is a value, and it is determined that the result of the positional deviation correction lacks reliability. In this case, the optical writing device control unit 120 executes the processing from S910 again based on the instruction from the sensor control unit 123. As a result, the misalignment correction is executed in a state where the amount of light emitted from the light emitting element is adjusted to an appropriate value by adjusting the amount of light.

  If the process from S910 is repeated again, the positional deviation correction is executed in a state where the irradiation light quantity of the light emitting element is adjusted to an appropriate value by the light quantity adjustment, so the light quantity adjustment in S915 and the process in S916 are cancelled. Then, the processing may be ended as it is. Accordingly, it is possible to reduce the overlap processing and simplify the processing, and to reduce the user downtime until the positional deviation correction is completed. With such processing, the misregistration correction operation according to the present embodiment is completed.

  In the light amount adjustment in S902 and S915, the sensor control unit 123 performs error determination when the driving power of the light emitting element set as a result of the adjustment exceeds a predetermined threshold value. When error determination is performed, the sensor control unit 123 retries the light amount adjustment. If the error determination is not resolved even after the light amount adjustment is repeated three times due to the retry by the error determination, the optical writing device control unit 120 performs a return operation for eliminating the error.

  In the returning operation, the cleaning mechanism provided in the pattern detection sensor 117 performs cleaning by scraping the light emitting surface of the light emitting element and the light receiving element and the adhering matter such as toner adhering to the light receiving surface. Instead of providing the above-described cleaning mechanism, the user may be prompted to perform cleaning by displaying on the display panel 24.

  If the error determination is not resolved even after the light amount adjustment is performed again after such a return operation, there is a high possibility that a defect has occurred in the pattern detection sensor 117. Therefore, in such a case, the optical writing device control unit 120 notifies the user of the malfunction of the pattern detection sensor 24 by displaying on the display panel 24.

The effects of the misregistration correction operation according to this embodiment will be described with reference to FIGS. 11 (a) and 11 (b). FIG. 11A is a diagram showing a time series when starting the misregistration correction operation according to the present embodiment, and FIG. 11B is a diagram showing a time series according to the prior art. As shown in FIG. 11 (a), the positional deviation correcting operation according to the present embodiment, the optical writing device 111, the timing t _0, performs the activation and stabilization of the light emitting element is first included in the pattern detection sensor 117.

When the light intensity of the light emitting element is stabilized, then, at the timing t _1, the write control unit 121 controls the light source unit 281 to start drawing the positional deviation correction mark 400. As a result, misalignment correction is executed. Thereafter, at the timing t ₂ to misalignment correction operation is completed, with a cleaning of the conveyor belt 105 is started, by using the cleaning period, the sensor control unit 123 adjusts the amount of light of the light emitting element.

As described above, the cleaning period requires about 3 seconds. On the other hand, since the light amount adjustment of the light emitting element can be completed in about 2 seconds, it can be completed within the cleaning period. At timing t ₃ when the cleaning and the light quantity adjustment is completed, execution of the image formation output is possible.

In contrast, in the case of the prior art shown in FIG. 11 (b), at timing t _1, the sensor control unit 123 starts the light quantity adjustment of the light emitting element. Then, at the timing t _{1 ′} when the sensor control unit 123 completes the light amount adjustment, the writing control unit 121 controls the light source device 281 and starts drawing the misregistration correction mark 400. Thus, in the positional deviation correction operation according to the present embodiment, minute from the timing t ₁ of the sensor control unit 123 performs light intensity adjustment of the light emitting element of the period from the timing t _1', provide a faster execution start timing of the displacement correction Can do.

Thereafter, at the timing t _{2'misregistration} correction operation is completed, the cleaning of the conveyor belt 105 is started. Thereafter, a timing cleaning is complete, the slow t _3'than the timing t ₃ when the above-described execution of image forming output is possible.

  As described above, in the misalignment correction operation according to this embodiment, it is recommended that the light amount adjustment be performed in advance by determining the determination items illustrated in FIG. 10, or the light amount adjustment is omitted. However, in the case where the processing period is not shortened, or the downtime for the user does not occur even if the light amount adjustment is performed, the light amount is reduced before the drawing of the misalignment correction mark 400 is started as in the conventional case. Make adjustments.

  On the other hand, if downtime for the user becomes more problematic, or if the accuracy of misregistration correction does not drop significantly even with subsequent light intensity adjustment, the transport after the misregistration correction is completed. The amount of light is adjusted afterwards using the cleaning period of the belt 105. Thereby, in a specific case, the prior light amount adjustment is omitted, so that the execution start timing of misalignment correction is advanced, and as a result, the completion timing of misalignment correction can be advanced.

  Further, in the positional deviation correction operation according to the present embodiment, when the light quantity adjustment is performed after the positional deviation correction by omitting the prior light quantity adjustment based on the above-described function, the driving power of the light emitting element applied in the positional deviation correction And the driving power of the light emitting element after the light amount adjustment is performed. If the difference between the two is equal to or greater than a predetermined value, it is determined that the reliability of the positional deviation correction is low, and the positional deviation correction is performed again.

  Thereby, even when the light amount adjustment is executed after the positional deviation correction, it is confirmed that the light quantity of the light emitting element is appropriate afterwards, and thus the reliability of the positional deviation correction can be maintained. In addition, since the light amount adjustment at that time is performed during the cleaning period of the transport belt 105, the user's convenience is improved without increasing the user's downtime by the light amount adjustment.

  Furthermore, as described above, when it is determined that the reliability of the misregistration correction is low, the misregistration correction is performed again, and therefore the result of the misregistration correction with low reliability is applied to execute the image formation output. The image quality of the output image can be maintained in any case.

  In the above-described embodiment, as illustrated in FIG. 3, a system in which an image is directly transferred from the photosensitive drum 109 onto the sheet surface of the sheet conveyed by the conveyance belt 105 has been described as an example. That is, the case where the conveyance belt 105 as a conveyance body conveys a sheet has been described as an example.

  In addition, as shown in FIG. 12, the above embodiment is applied even to an intermediate transfer system in which an image formed by being transferred from the photosensitive drum 109 onto the conveying belt 105 is further transferred onto the paper surface. It is possible to obtain the same effects as described above. In this case, the conveyance belt 105 which is an intermediate transfer belt conveys an image as a conveyance body.

  In the image forming apparatus 1 in FIG. 12, the driving roller 108 is controlled to rotate the conveyance belt 105. At this time, a secondary transfer roller 119 facing the driving roller 108 with the conveying belt 105 interposed therebetween is disposed. The secondary transfer roller 119 increases the transfer efficiency by pressing the paper against the transport belt 105 when transferring the toner image formed on the transport belt 105 to the paper. When the misregistration correction using the misregistration correction mark 400 as shown in FIG. 8 is executed and completed, the toner adheres to the secondary transfer roller 119. In order to reduce this, a bias voltage opposite to the toner charge is applied to the secondary transfer roller 119 during image formation of the mark. Further, after the last pattern of the misregistration correction mark 400 passes just below the secondary transfer roller 119, the cleaning process of the transport belt 105 and the secondary transfer roller 119 is performed.

  This cleaning process is generally performed for a period of about 11 seconds. That is, the optical writing device control unit 120 controls the driving roller 107 for 11 seconds after the sensor control unit 123 detects the last pattern included in the misregistration correction mark 400 in the above-described misregistration correction. Continue to rotate the belt 105. At this time, it takes 2 seconds from the detection of the last pattern until it reaches the position immediately below the secondary transfer roller 119, and thereafter, control is performed such that the bias voltage of the secondary transfer roller 119 is vibrated positively or negatively within 6 seconds. The toner adhering to the secondary transfer roller 119 is peeled off and retransferred to the conveyor belt 105. The retransferred toner is removed by the belt cleaner 118 in 3 seconds as described above.

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,
117 pattern detection sensor,
118 belt cleaner,
120 optical writing device controller,
121 write controller,
122 counting part,
123 sensor control unit,
124 correction value calculation unit,
125 reference value storage unit,
126 correction value storage unit,
170 sensor element,
171 light emitting element,
172 specular reflection light receiving element,
173 diffuse reflection light receiving element,
280 reflector,
281,281BK, 281Y, 281M, 281C Light source device,
282, 282BK, 282Y, 282M, 282C Mirror 283 Horizontal synchronization detection sensor 400 Misalignment correction mark,
401 misalignment correction pattern sequence,
411 start position correction pattern,
412 Drum interval correction pattern,
413 Sub-scanning direction correction pattern,
414 Main scanning direction correction pattern

JP 2008-299311 A

Claims (12)

A light source controller that controls a light source that emits a light beam to a plurality of photoconductors arranged in the sub-scanning direction to form an electrostatic latent image on the photoconductor by irradiating the light beam;
Detecting that the image transferred to the surface of the carrier has reached a position facing the sensor based on an output signal of a sensor that images the surface of the carrier to which the image developed on the photoconductor is transferred An image detector to perform,
A detection period counting unit that counts a detection period from when the light source control unit starts drawing a predetermined pattern until the image detection unit detects the pattern conveyed by the conveyance body;
Based on a difference between a reference value that is a reference period from when the light source control unit starts drawing the pattern to when the image detection unit detects the predetermined pattern, and the counted detection period. A correction value calculation unit for calculating a correction value for correcting the timing of irradiating the light source with the light beam;
A developer removing unit that removes the developer on the carrier;
When executing the correction operation from when the pattern is drawn to when the correction value is calculated, the amount of light emitted from the light emitting unit that irradiates the surface of the transport body in the sensor depends on the amount of reflected light from the surface of the transport body. A light amount adjustment unit that performs a light amount adjustment operation to adjust based on the received signal,
The light amount adjustment unit completes the first timing before the light source control unit starts drawing the pattern, and the control of the light source for the light source control unit to draw the pattern, and the arrival determination unit After detecting that the end of the pattern has reached the predetermined position, the second timing is a period for causing the developer removing unit to remove the developer on the transport body. An optical writing apparatus capable of executing a light amount adjustment operation and determining whether the light amount adjustment operation is to be executed at any of the first timing and the second timing. When the light amount adjustment unit performs the light amount adjustment operation at the second timing, the light amount of the light emitting unit after the light amount adjustment operation is compared with the light amount of the light emitting unit applied in the correction operation. A light intensity comparison unit;
The light amount comparison unit performs the correction operation again when the difference between the light amount of the light emitting unit after the light amount adjustment operation and the light amount of the light emitting unit applied in the correction operation is a predetermined value or more. The optical writing apparatus according to claim 1, wherein an instruction is given.   The light amount adjustment unit determines whether to execute the light amount adjustment operation at any of the first timing and the second timing based on the execution timing of the correction operation. Optical writing device.   The light amount adjusting unit is configured to perform the first timing based on a temperature of a fixing unit included in the image forming apparatus when the correction operation is executed during warm-up of the image forming apparatus in which the optical writing device is mounted. 4. The optical writing device according to claim 2, wherein it is determined at which of the second timing and the light amount adjustment operation is executed. 5.   5. The optical writing device according to claim 4, wherein the light amount adjustment unit performs the light amount adjustment operation at the first timing when a temperature of the fixing device is equal to or lower than a predetermined value.   The light amount adjustment unit performs the light amount adjustment operation at the first timing when the correction operation is performed after image formation output of an image forming apparatus in which the optical writing device is mounted. The optical writing device according to claim 3. An in-machine temperature storage unit that stores the in-machine temperature of the image forming apparatus in which the optical writing device is mounted when the correction operation is performed;
The light amount adjustment unit is configured to adjust the first timing and the second timing based on a difference between an in-machine temperature of the image forming apparatus and an in-machine temperature stored in the in-machine temperature storage unit when the correction operation is performed. 7. The optical writing apparatus according to claim 3, wherein it is determined which of the light quantity adjustment operations is executed.   The light amount adjustment unit is configured to perform the first timing when a difference between an in-machine temperature of the image forming apparatus and an in-machine temperature stored in the in-machine temperature storage unit is greater than or equal to a predetermined value when the correction operation is performed. The optical writing device according to claim 7, wherein the light amount adjustment operation is executed in step (a).   The light amount adjustment unit performs the light amount adjustment operation at the second timing when the correction operation is performed before image formation output of an image forming apparatus in which the optical writing device is mounted. The optical writing device according to claim 3.   The light amount adjustment unit performs the light amount adjustment operation at the second timing when the correction operation is executed by interrupting the image forming output of the image forming apparatus in which the optical writing device is mounted. 10. The optical writing device according to claim 3,   11. The light according to claim 1, wherein the light amount adjustment unit performs the light amount adjustment operation at the first timing when the correction operation is instructed by a user. Writing device. A light source controller that controls a light source that emits a light beam to a plurality of photoconductors arranged in the sub-scanning direction to form an electrostatic latent image on the photoconductor by irradiating the light beam;
Detecting that the image transferred to the surface of the carrier has reached a position facing the sensor based on an output signal of a sensor that images the surface of the carrier to which the image developed on the photoconductor is transferred An image detector to perform,
A detection period counting unit that counts a detection period from when the light source control unit starts drawing a predetermined pattern until the image detection unit detects the pattern conveyed by the conveyance body;
Based on a difference between a reference value that is a reference period from when the light source control unit starts drawing the pattern to when the image detection unit detects the predetermined pattern, and the counted detection period. A correction value calculation unit for calculating a correction value for correcting the timing of irradiating the light source with the light beam;
A developer removing unit that removes the developer on the carrier;
When executing the correction operation from when the pattern is drawn to when the correction value is calculated, the amount of light emitted from the light emitting unit that irradiates the surface of the transport body in the sensor depends on the amount of reflected light from the surface of the transport body. A positional deviation correction method for an optical writing device, including a light amount adjustment unit that performs a light amount adjustment operation to adjust based on the received signal,
The light amount adjusting unit is
The first timing before the light source control unit starts drawing the pattern, and the light source control unit completes the control of the light source for drawing the pattern, and the arrival determination unit completes the end of the pattern. Is detected at the predetermined position, and the light amount adjusting operation is performed at any of the second timing which is a period for causing the developer removing unit to remove the developer on the transport body. Decide whether to run,
A method of correcting misalignment of an optical writing device, wherein the light amount adjustment operation is executed at the determined timing.

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