JP2019072888A - Optical writing device and image formation apparatus - Google Patents

Abstract

To provide an optical writing device and an image formation apparatus that correct distortion of an image due to characteristic variation between lenses constituting a lens array.SOLUTION: While a photoreceptor drum of an image formation apparatus is stopped from being driven to rotate, OLEDs on an optical axis and four OLEDs on a circumference having its center on the optical axis are turned ON for each of lenses 400 constituting a multi-lens array 201, and five representative points are thus exposed to form an electrostatic latent image. Then while the photoreceptor drum is driven to rotate, the electrostatic latent image is developed, and a toner image is detected by a line sensor. An offset component of a quantity of deviation in exposure position of each OLED and a magnification component are calculated, and after those components are used to estimate quantities of deviation in position of other OLEDs, exposure positions of the respective OLEDs are corrected corresponding to the quantities of deviation in position.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an optical writing apparatus and an image forming apparatus, and more particularly to a technology for detecting a shift in exposure position in a line optical type optical writing apparatus.

  Conventionally, in an electrophotographic image forming apparatus, an optical scanning type optical writing apparatus is used which performs optical writing on a photosensitive drum by deflecting outgoing light of a laser diode using a scanning optical system. The scanning optical system is difficult to miniaturize due to its structure, and it is technically difficult to narrow the beam diameter of the outgoing light. For this reason, there is a limit to miniaturizing the image forming apparatus equipped with the optical scanning type optical writing device, reducing the cost, and increasing the resolution.

  On the other hand, in a line optical type optical writing device in which light sources in which light emitting elements of minute dots are arranged in lines are combined with a lens array, for example, light sources in which about 30,000 light emitting elements are arrayed in the main scanning direction In combination with a lens array in which several hundreds of lenses are arranged in the scanning direction, one lens forms an image for each region where the light source is divided into several hundred.

  If a line optical type optical writing device is used, it is easy to miniaturize and reduce the cost of both the light source and the lens array, and one for each divided area of the light source using the light emitting elements of minute dots. Since an image is formed by a lens, high resolution can be achieved. Therefore, if the line optical type optical writing device is mounted, downsizing, cost reduction, and high resolution of the image forming apparatus can be achieved.

JP, 2008-224957, A

  However, in the case of using a multi-lens array (MLA: Multi-Lens Array) as the lens array in the line optical type optical writing apparatus, the characteristics of the individual lenses in the mold used for molding the multilens and the characteristics of the mold itself There may be errors in the shape of the lens depending on it.

  For example, as shown in FIG. 14A, when the light L emitted from the light emitting element 1402 constituting the light source 1401 is exposed on the photosensitive member 1404 via the lens 1403, the light L with respect to the chief ray direction of the light L is exposed. When the optical axis 1403a of the lens 1403 is inclined, the emitted light L is irradiated at a position different from the optical path L 'when the optical axis 1403a is not inclined by the optical path offset z on the photosensitive member 1404.

  More specifically, as shown in FIG. 14B, the light L emitted from the light emitting element 1402 is incident on the lens 1403 at an incident angle i equal to the inclination angle of the optical axis 1403a of the lens 1403 and at a refraction angle j. It emits inward. Thereafter, the light is emitted out of the lens 1403 at an emission angle i. As described above, when the outgoing light L is refracted, the light enters the photosensitive member 1404 at a position deviated from the optical path L ′ by the optical path offset z from the optical path L ′ when the optical axis 1403a is not inclined and the incident angle i is 0 degree.

  The larger the inclination angle of the optical axis 1403a, the larger the incident angle i and the refraction angle j, so the optical path offset z becomes larger. Therefore, if the inclination angle of the optical axis 1403a differs for each lens 1403, the magnitude of the optical path offset z will vary.

  In addition, when the tilt direction of the optical axis is different, the shift direction of the exposure position is different. FIG. 15 shows an exposure position 1501 by a light emitting element positioned near the axis and an exposure position 1502 by four light emitting elements positioned concentrically equidistant from the optical axis when the optical axis of the lens is not inclined; It is a figure which illustrates how 1503 and 1504 and 1505 shift according to the inclination direction of an optical axis.

  For example, since the optical axis of the lens # 1 is inclined in the upper left direction in the drawing, the exposure position is shifted to the lower right and becomes positions 1511, 1512, 1513, 1514, and 1515. In addition, since the optical axis of the lens # 2 is inclined in the lower left direction in the drawing, the exposure position is shifted to the upper right, and becomes positions 1521, 1522, 1523, 1524 and 1525.

  Furthermore, even if the inclination angle and the inclination direction of the optical axis are the same, if the magnification differs for each lens due to the lens precision being dispersed in the mold, the magnitude of the optical path offset z will be varied, and the printed image There is a problem that distortion occurs.

  The present invention has been made in view of the above problems, and provides an optical writing device and an image forming apparatus that corrects distortion of an image caused by characteristic variations among lenses that constitute a lens array. With the goal.

  In order to achieve the above object, the optical writing device according to the present invention has a plurality of sets of a plurality of non-single-crystal light emitting means and a lens for focusing the light emitted from the plurality of non-single-crystal light emitting means An optical writing device in which a plurality of lenses constitute a lens array, wherein at least one of the plurality of sets is emitted from some of the non-single-crystal light emitting means among the plurality of non-single-crystal light emitting means A detection unit that detects an exposure position at which light is exposed on the image forming surface; a calculation unit that calculates a positional deviation amount from the reference position, which is a target exposure position, of the exposure position detected by the detection unit; The position from the reference position of the exposure position of the non-single-crystal light emission means other than the one portion of the non-single-crystal light emission means using the positional deviation amount calculated by the calculation means for each set of exposure positions detected by the detection means Estimate to estimate the amount of deviation Using a stage, the calculating unit positional deviation amount was calculated, and the estimating means positional shift amount estimated, characterized in that it comprises a correction means for correcting the exposure position for the all of the plurality of pairs.

  In this way, the exposure position of the light emitted from the non-single crystal light emitting means is detected, the positional deviation amount of the exposure position due to the characteristic variation between the lenses is calculated, and the exposure position is calculated using the positional deviation amount. Since the correction is performed, the distortion of the image can be corrected.

  In this case, the lens array is configured by arranging a plurality of lens groups, and each of the lens groups is molded using a common mold, and the detection unit is configured to select one of the plurality of lens groups. The exposure position is detected for at least one set in only one lens group, and the correction means calculates the calculation for the one lens group for lenses corresponding to each other between the lens groups formed positively by the common mold. The exposure position may be corrected using the positional deviation amount calculated by the means and the positional deviation amount estimated by the estimation means.

  Further, at least one of the plurality of non-single-crystal light emitting means and the lens is associated with one or more of the temperature distribution, the pressure distribution, and the stress distribution after molding in the lens array molding. The correction means is selected from the set, and the correction means is, for the at least one set, a temperature distribution at the time of molding the lens array from the positional deviation amount calculated by the calculation means and the positional deviation amount estimated by the estimation means. The exposure position may be corrected according to one or more of the pressure distribution and the stress distribution after molding.

  Further, the detection means detects an exposure position on the imaging surface in a state where the optical writing device is incorporated in the image forming apparatus, and the correction means is molded by a mold for molding the lens array. The storage means for storing the amount of misalignment expected for each lens in a state in which the optical writing device is not incorporated in the image forming apparatus for the two or more lenses, and the amount of misalignment calculated by the calculating means In accordance with the above, the exposure position related to the lenses other than the at least one set of the two or more lenses may be corrected using the position shift amount obtained by changing the position shift amount stored in the preliminary storage unit. .

  Further, the calculation means is a position from the reference position of the exposure position detected by the detection means with respect to the non-single crystal light emission means of which the reference position is closest to the optical axis of the lens among the plurality of non single crystal light emission means. The shift amount may be calculated as an offset component, and the correction unit may correct the exposure position according to the offset component.

  Here, the plurality of non-single-crystal light emitting units are arranged in a staggered manner so as to be mutually different positions in the main scanning direction, and the calculation unit is configured to select the reference position among the plurality of non-single-crystal light emitting units. For one non-single crystal light emitting means other than the non-single crystal light emitting means closest to the optical axis of the lens, the main scanning of the offset component is obtained from the positional deviation amount from the reference position of the exposure position detected by the detection means. It is more preferable that the positional deviation amount excluding the directional component is calculated as a magnification component in the main scanning direction, and the correction means corrects the exposure position according to the magnification component in the main scanning direction.

  Further, the plurality of non-single-crystal light emitting units are arranged in a staggered manner so as to be different from each other in the main scanning direction, and the calculation unit is arranged in the main scanning direction among the plurality of non-single-crystal light emitting units. With respect to two non-single-crystal light emitting units positioned on both sides of the non-single-crystal light emitting unit whose reference position is closest to the optical axis of the lens, the positional deviation of the exposure position detected by the detection unit from the reference position The positional deviation amount excluding the main scanning direction component among the offset components may be calculated as a magnification component in the main scanning direction, and the correction unit may correct the exposure position according to the magnification component in the main scanning direction. .

  Further, the plurality of non-single-crystal light emitting units are arranged in a staggered manner so as to be different from each other in the main scanning direction, and the calculation unit is arranged in the main scanning direction among the plurality of non-single-crystal light emitting units. The position shift from the reference position of the exposure position detected by the detection means for one non-single crystal light emission means different from the non-single crystal light emission means closest to the optical axis of the lens in the sub scanning direction orthogonal to The positional deviation amount excluding the sub scanning direction component of the offset component from the amount is calculated as a magnification component in the sub scanning direction, and the correction means corrects the exposure position according to the magnification component in the sub scanning direction. May be

  Further, the plurality of non-single-crystal light emitting units are arranged in a staggered manner so as to be different from each other in the main scanning direction, and the calculation unit is arranged in the main scanning direction among the plurality of non-single-crystal light emitting units. Regarding the two non-single-crystal light emitting means located on both sides of the non-single-crystal light emitting means closest to the optical axis of the lens in the sub scanning direction orthogonal to each other, from the reference position of the exposure position detected by the detection means The positional deviation amount excluding the wind scanning direction component of the offset component is calculated as a magnification factor component in the sub scanning direction from the positional deviation amount in the sub scanning direction, and the correction means is configured to expose the exposure position according to the magnification component in the sub scanning direction. May be corrected.

  Preferably, the non-single crystal light emitting means is an OLED.

  Further, the plurality of non-single-crystal light emitting means are disposed in a staggered manner so as to be different from each other in the main scanning direction, and at least one set is a set located at an end in the main scanning direction. Good.

  In addition, a compression that stores an average value of positional deviation amounts from the reference position of the exposure position of the emitted light for each non-single-crystal light emitting means, and a difference between the positional deviation amount for each non-single-crystal light emitting means and the average value. A storage unit may be provided, and the correction unit may correct the exposure position using a positional shift amount calculated from the average value and the difference stored in the compression storage unit.

  An image forming apparatus according to the present invention is characterized by including the optical writing device according to the present invention.

FIG. 1 is a diagram showing a main configuration of an image forming apparatus according to a first embodiment. (A) is a figure which shows the main structures of the optical writing device 100, (b) is a schematic plan view of the OLED panel part 200, the sectional view in an AA 'line, and the sectional view in a CC' line. The schematic plan view shows a state in which the sealing plate 211 is removed. (A) is a block diagram showing the configuration of the TFT thermal insulator 214, and (b) is a circuit diagram showing the configuration of the selection circuit 301 and the light emitting block 302. FIG. 6 is a block diagram showing a main configuration of an ASIC 220. FIG. 6 is a block diagram showing the main configuration of a control unit 150. (A) is a plan view showing an array of multi lenses, (b) is a plan view showing an array of pixels corresponding to one lens, and (c) is a plan view illustrating an exposure position. 5 is a flowchart showing an operation of the image forming apparatus 1; Among the magnification components of the exposure positional deviation amount, (a) is a graph showing a magnification component in the sub scanning direction, and (b) is a graph showing a magnification component in the main scanning direction. (A) is a table showing shift amounts of exposure positions of pixels in the first to third rows, and (b) is a table showing shift amounts of exposure positions of pixels in the fourth to fifth rows is there. (A) is a table showing shift amounts of exposure positions of pixels in the sixth to eighth rows, and (b) is a table showing shift amounts of exposure positions of pixels in the ninth to tenth rows is there. With respect to the second embodiment, (a) is a graph illustrating temperature distribution, pressure distribution or residual stress distribution after molding during molding, and (b) shows a lens 400 for which the shift amount of the exposure position should be detected. It is a top view which illustrates. It is a figure showing the main composition of image forming device 1 concerning a modification. It is a figure which illustrates the positional relationship of the exposure position in case there is no position shift, and the exposure position in case there is position shift. (A) is a figure explaining the structure of a general optical writing device, (b) is a figure explaining the shift of the exposure position by the inclination of the optical axis 1403a of the lens 1403. It is a figure which illustrates the relationship between the inclination direction of the optical axis of a lens, and the shift direction of exposure position.

Hereinafter, embodiments of an optical writing device and an image forming apparatus according to the present invention will be described with reference to the drawings.
[1] First Embodiment An image forming apparatus according to a first embodiment of the present invention corrects image distortion in an optical writing apparatus using a multi-lens array molded using a master mold repeatedly. Therefore, image distortion is detected only for a portion corresponding to one master mold, and the detection result is diverted to the entire multi-lens array to efficiently correct the image distortion.
(1-1) Configuration of Image Forming Apparatus First, the configuration of the image forming apparatus according to the present embodiment will be described.

  As shown in FIG. 1, the image forming apparatus 1 is a so-called tandem type color printer, and an image for forming toner images of yellow (Y), magenta (M), cyan (C) and black (K) colors. The forming stations 110Y, 110M, 110C and 110K are provided. The image forming stations 110Y, 110M, 110C and 110K have photosensitive drums 101Y, 101M, 101C and 101K which rotate in the direction of arrow A.

  Around the photosensitive drums 101Y, 101M, 101C and 101K, charging devices 102Y, 102M, 102C and 102K, optical writing devices 100Y, 100M, 100C and 100K, and developing devices 103Y, 103M, 103C and 103K along the outer peripheral surface. The primary transfer rollers 104Y, 104M, 104C and 104K and the cleaning devices 105Y, 105M, 105C and 105K are disposed.

  Further, line sensors 160Y, 160M, 160C and 160K are disposed downstream of the developing devices 103Y, 103M, 103C and 103K in the rotational direction of the photosensitive drums 101Y, 101M, 101C and 101K. The line sensors 160Y, 160M, 160C and 160K detect which position in the main scanning direction the toner is attached on the outer peripheral surface of the photosensitive drums 101Y, 101M, 101C and 101K, and notify the control unit 150 Do. Further, since the line sensors 160Y, 160M, 160C, and 160K repeatedly perform detection at a sufficiently short time interval, the control unit 150 can specify the toner adhesion position in the sub scanning direction from the detection timing.

  The charging devices 102Y, 102M, 102C and 102K uniformly charge the outer peripheral surfaces of the photosensitive drums 101Y, 101M, 101C and 101K. The optical writing devices 100Y, 100M, 100C and 100K are so-called OLED-PHs (Organic Light Emitting Diodes-Print Heads), which expose the outer peripheral surface of the photosensitive drums 101Y, 101M, 101C and 101K to form electrostatic latent images Form

  The developing devices 103Y, 103M, 103C, and 103K supply toners of Y, M, C, and K colors, develop electrostatic latent images, and form toner images of Y, M, C, and K colors. The primary transfer rollers 104Y, 104M, 104C and 104K electrostatically transfer the toner images carried by the photosensitive drums 101Y, 101M, 101C and 101K onto the intermediate transfer belt 106 (primary transfer).

  The cleaning devices 105Y, 105M, 105C, and 105K remove charges remaining on the outer peripheral surfaces of the photosensitive drums 101Y, 101M, 101C, and 101K after primary transfer, and remove residual toner. In the following, when describing the configuration common to the image forming stations 110Y, 110M, 110C and 110K, the characters YMCK will be omitted.

  The intermediate transfer belt 106 is an endless belt and is stretched around the secondary transfer roller pair 107 and the driven rollers 108 and 109, and rotationally travels in the arrow B direction. By performing primary transfer in accordance with the rotational travel, toner images of Y, M, C, and K colors are superimposed on each other to form a color toner image. The intermediate transfer belt 106 conveys the color toner image to the secondary transfer nip of the secondary transfer roller pair 107 by rotating and traveling with the color toner image carried.

  The two rollers constituting the secondary transfer roller pair 107 form a secondary transfer nip by being pressed against each other. A secondary transfer voltage is applied between these rollers. When the recording sheet S is supplied from the paper feed tray 120 at the same timing as the conveyance of the color toner image by the intermediate transfer belt 106, the color toner image is electrostatically transferred onto the recording sheet S at the secondary transfer nip (secondary Transcription).

  The recording sheet S is conveyed to the fixing device 130 in a state of carrying a color toner image, thermally fixed on the color toner image, and then discharged onto the sheet discharge tray 140.

The image forming apparatus 1 further includes a control unit 150. When the control unit 150 receives a print job from an external apparatus such as a PC (Personal Computer), the control unit 150 controls the operation of the image forming apparatus 1 to execute image formation.
(1-2) Configuration of Optical Writing Device 100 Next, the configuration of the optical writing device 100 will be described.

  As shown in FIG. 2A, the optical writing device 100 is configured to support the OLED panel unit 200 and the multi-lens array 201 by the holder 202, and the emitted light L of the OLED panel unit 200 is a multi-lens array. The light is condensed on the outer peripheral surface of the photosensitive drum 101 by 201. A cable or the like for connecting the optical writing device 100 and another device of the image forming device 1 is not shown.

  As shown in FIG. 2B, the OLED panel unit 200 includes a glass substrate 210, a sealing plate 211, a driver IC (Integrated Circuit) 212, and the like. A TFT (Thin Film Transistor) circuit 214 is formed on a glass substrate 210, and 15,000 OLEDs (not shown) are arranged in a line at a 21.2 μm pitch (1200 dpi) along the main scanning direction. ing. The linear OLEDs are arranged in a staggered manner in the present embodiment, but may be arranged in a line.

  Further, the substrate surface on which the OLED of the glass substrate 210 is disposed is a sealing region, and the sealing plate 211 is attached with the spacer frame 213 interposed therebetween. As a result, the sealing region is sealed in a state of sealing dry nitrogen or the like so as not to be exposed to the outside air. In order to absorb moisture, a hygroscopic agent may be additionally sealed in the sealing region. The sealing plate 211 may be, for example, sealing glass, or may be made of a material other than glass.

Outside the sealing area of the glass substrate 210, a driver IC 212 is mounted. An application specific integrated circuit (ASIC) 220 of the control unit 150 inputs a digital luminance signal to the driver IC 212 via the flexible wire 221. The driver IC 212 converts the digital luminance signal into an analog luminance signal (hereinafter simply referred to as "luminance signal") and inputs it to the drive circuit of each OLED. The drive circuit generates a drive current for the OLED in response to the luminance signal. In the present embodiment, the luminance signal is a voltage signal.
(1-3) TFT circuit 214
Next, the configuration of the TFT circuit 214 will be described.

  As shown in FIG. 3A, in the TFT circuit 214, 100 15,000 OLEDs 320 are grouped into 150 light emission blocks 302 each. In addition, 150 current DACs (Digital to Analogue Converters) 300 are built in the driver IC 212, and correspond to the light emitting blocks 302 one by one, respectively. The current DAC 300 is a digitally controllable variable current source. The light emitting blocks 302 are arranged in the main scanning direction.

  A selection circuit 301 is disposed on each circuit going from the current DAC 300 to the light emitting block 302. Furthermore, on the circuit from the driver IC 212 to the selection circuit 301, a reset circuit 303 is connected. Each current DAC 300 sequentially outputs a luminance signal to so-called 100 OLEDs 320 by so-called rolling drive. One current DAC 300 is shared in time by the 100 OLEDs 320 included in the corresponding light emission block 302.

  As shown in FIG. 3B, the light emitting block 302 is composed of 100 light emitting pixel circuits, and each light emitting pixel circuit has one capacitor 321, one driving TFT 322 and one OLED 320. Further, the selection circuit 301 includes a shift register 311 and 100 selection TFTs 312, and the reset circuit 303 includes a reset TFT 340.

  The shift register 311 is connected to the gate terminal of each of the 100 selection TFTs 312, and sequentially turns on the selection TFTs 312. The source terminal of the selection TFT 312 is connected to the current DAC 300 via the write wiring 330, and the drain terminal is connected to the first terminal of the capacitor 321 and the gate terminal of the drive TFT 322.

  When the shift register 311 turns on the selection TFT 312, the output current of the current DAC 300 flows to the first terminal of the capacitor 321, and charge is accumulated in the capacitor 321. The charge stored in the capacitor 321 is held until reset by the reset circuit 303.

  The first terminal of the capacitor 321 is also connected to the gate terminal of the drive TFT 322, and the second terminal of the capacitor 321 is connected to the source terminal of the drive TFT 322 and the power supply wiring 331. The drain terminal of the driving TFT 322 is connected to the anode terminal of the OLED 320, and the cathode terminal of the OLED 320 is connected to the ground wiring 332. The ground wiring 332 is connected to the ground terminal GND, and the power supply wiring 331 is connected to the constant voltage source Vpwr.

  The constant voltage source Vpwr is a supply source of drive current supplied to the OLED 320, and the drive TFT 322 is configured to drive the drive current corresponding to the luminance signal voltage held between the first and second terminals of the capacitor 321. Supply to For example, when a luminance signal corresponding to H is written to the capacitor 321, the drive TFT 322 is turned on, and the OLED 320 emits light. Further, when a luminance signal corresponding to L is written to the capacitor 321, the drive TFT 322 is turned off and the OLED 320 does not emit light. The luminance signal written to the capacitor 321 is held until the next luminance signal is written or the reset TFT 340 is turned on.

  When the reset TFT 340 is turned on, the line from the current DAC 300 to the capacitor 321 is reset to the reset potential. The reset potential may be the Vdd potential or the ground potential, and an appropriate potential may be selected. Further, although the case where the OLED 320 does not emit light in the reset state is described in this embodiment, the OLED 320 may emit light in the reset state.

  Although the case where the drive TFT 322 is a p-channel is described as an example in this embodiment, it goes without saying that an n-channel drive TFT 322 may be used.

Further, in the present embodiment, the reset circuit 303 is provided separately from the driver IC 212 and is under the control of the driver IC 212. Alternatively, the reset circuit 303 may be incorporated in the driver IC 212. . The function of the reset circuit 303 may be realized by changing the polarity of the current output from the current DAC at the time of reset and at the time of writing. Also, instead of the reset TFT 340, a switching element other than a TFT may be used.
(1-4) ASIC 220
Next, the ASIC 220 will be described.

  As shown in FIG. 4, the ASIC 220 includes a drive current correction unit 401 and a dot count unit 402, and the dot count unit 402 includes 15,000 dot counters 403 corresponding to each of the OLEDs 320. A predetermined count value is added to the dot counter 403 each time the corresponding OLED 320 is issued once.

The drive current correction unit 401 refers to the dot counter 403 for each of the OLEDs 320 and corrects the amount of drive current each time the counter value reaches the dot count threshold. At the time of correcting the drive current amount, the drive current amount correction unit 401 refers to the drive current amount, the luminous efficiency, the emitted light amount, and the deterioration degree for each of the OLEDs 320. Alternatively, the in-machine temperature of the image forming apparatus 1 may be measured using a temperature sensor, and the driving current amount may be corrected using a temperature correction coefficient stored in advance for each in-machine temperature.
(1-5) Control unit 150
Next, the configuration of the control unit 150 will be described.

  As shown in FIG. 5, the control unit 150 includes a central processing unit (CPU) 501, a read only memory (ROM) 502, a random access memory (RAM) 503, etc., and the image forming apparatus 1 is powered on. Then, the CPU 501 reads the boot program from the ROM and activates it, and executes the operating system (OS) and control program read from the HDD (Hard Disk Drive) 504, using the RAM 503 as a work storage area.

  Further, the control unit 150 controls various operation timings of the image forming apparatus 1 using the timer 505, and refers to detection timing by a sensor. A NIC (Network Interface Card) 506 is used to communicate with an external device such as a PC (Personal Computer) via a communication network such as a LAN (Local Area Network). When the control unit 150 receives a print job from an external apparatus, the control unit 150 controls each unit of the image forming apparatus 1 to execute an image forming process according to the print job.

  In this case, the control unit 150 controls the photosensitive drum drive motor 510 to rotate the photosensitive drum 101, and uniformly charge the outer peripheral surface of the photosensitive drum 101 by the charging device 102, thereby writing light. It is exposed by the device 100 and developed by the developing device 103. The line sensor 160 detects the toner image formed by this. As described above, the control unit 150 incorporates the ASIC 220 and controls the operation of the optical writing device 100 via the ASIC 220.

  The CPU 501 refers to the clock signal to calculate the number of clocks from when the optical writing device 100 performs exposure to when the line sensor 160 detects a toner image, and the exposure position by the optical writing device 100 is detected by the line sensor 160 By comparing with the time (the number of clocks) required to reach the position, it is possible to detect the positional deviation of the toner image in the sub-scanning direction.

In the main scanning direction, the positional deviation of the toner image can be detected by comparing the detection position by the line sensor 160 with the exposure position.
(1-6) Detection of Exposure Position Next, the detection of the deviation of the exposure position caused by the optical axis inclination of the lenses constituting the multi-lens array 201 and the lens accuracy will be described.

  As shown in FIG. 6A, the multi-lens array 201 is provided with 3 rows × 50 rows of lenses 400 molded by using a 3 rows × 5 columns master mold repeatedly 10 times. Therefore, the lens 400 has the same characteristic for every five lines in the main scanning direction, and the same optical axis inclination and lens accuracy are repeated for 10 cycles. The 150 lenses 400 collect the emitted light L of 100 OLEDs 320 respectively. As a result, emitted light L of 15,000 OLEDs 320 is condensed on the outer peripheral surface of the photosensitive drum 101.

  As shown in FIG. 6B, the 100 OLEDs 320 emitting the emitted light L collected by one lens 400 are arranged in a staggered manner in 10 rows × 10 columns on the glass substrate 210. In the figure, the numbers # 1 to # 100 are assigned to the OLED 320 sequentially from the upstream in the main scanning direction.

  Of the 100 lenses 400, the five OLEDs 320 indicated by white circles in FIG. 6B, that is, the optical axis of the lens 400 (ie, the optical axis of the lens 400 (the OLED 320 located at the closest position to the optical center), and four equidistantly spaced from the optical axis of the lens 400, in other words, four circumferentially centered on the optical axis of the lens 400 The OLED 320 (# 6, # 51, # 60 and # 96) is turned on.

  The # 6 and # 96 OLEDs 320 sandwich the optical axis in the main scanning direction, and the # 51 and # 60 OLEDs 320 sandwich the optical axis in the sub-scanning direction. The light beams L emitted from the five OLEDs 320 expose five representative points on the outer peripheral surface of the photosensitive drum 101.

  FIG. 6C illustrates the exposure positions of five representative points. White circles 601, 602, 603, 604, and 605 indicate exposure positions (hereinafter referred to as "reference positions") when the lens 400 has no tilt of the optical axis and the lens accuracy is as designed, and black circles 611, 612, 613, 614, and 615 indicate exposure positions when the lens 400 is misaligned due to optical axis inclination or lens accuracy.

  In order to detect such positional deviation, the control unit 150 forms a positional deviation detection toner image on the outer peripheral surface of the photosensitive drum 101 as shown in FIG. 7 (S701).

  In normal image formation, the OLEDs 320 in the first to tenth rows are lit at different timings in synchronization with the rotation of the photosensitive drum 101, and the outer peripheral surface of the photosensitive drum 101 is exposed. By exposure, an electrostatic latent image of one line is formed.

  On the other hand, when detecting the positional deviation of the exposure position, the control unit 150 causes the charging device 102 to uniformly charge the outer peripheral surface of the photosensitive drum 101 while rotationally driving the photosensitive drum 101. Furthermore, when the photosensitive drum 101 is rotationally driven and the charged area reaches the exposure position of the optical writing device 100, exposure is performed in a state where the rotational driving of the photosensitive drum 101 is temporarily stopped.

  The misregistration detection toner image is an image of only one line, and as illustrated in FIG. 6B, for each lens 400 for a 3-row × 5-column lens 400 corresponding to one cycle of the master mold. Five OLEDs 320 are turned on. The five OLEDs 320 expose positions corresponding to the positions on the glass substrate 210 on the outer peripheral surface of the photosensitive drum 101.

  Therefore, as illustrated in FIG. 6C, the exposure positions of the five representative points do not necessarily coincide in the sub-scanning direction. Moreover, it goes without saying that the exposure positions of the five representative points are different from each other in the main scanning direction.

  Thereafter, the control unit 150 detects a toner image by the line sensor 160 (S702). Specifically, after forming an electrostatic latent image by exposure, the control unit 150 restarts the rotational driving of the photosensitive drum 101 and develops the electrostatic latent image by the developing device 103. Then, while the photosensitive drum 101 is driven to rotate, the toner image is repeatedly detected by the line sensor 160.

  The line sensor 160 is a sensor in which light receiving elements are arranged in a line in the main scanning direction, and can detect at which position in the main scanning direction a toner image is formed from the light receiving amount of each light receiving element. Further, if the toner image is repeatedly detected, the position of the toner image in the sub-scanning direction can also be detected depending on the timing at which it is detected.

  For example, the control unit 160 refers to the elapsed time (the number of clocks) after resuming the rotational driving of the photosensitive drum 101 after exposure, thereby determining at which position in the sub-scanning direction the toner image is formed. It can be identified.

  As shown in FIG. 6C, the control unit 160 compares the reference position stored in advance with the detection position, and shifts the exposure position of the OLED 320 (# 56) on the optical axis for each lens 400. The offset components Δx and Δy in the main scanning direction and the sub-scanning direction between the reference position 601 and the detection position 611 are calculated as displacement components (offset amounts) of the amount due to the inclination of the optical axis (S703).

  Using this offset component Δx, Δy, a displacement component (hereinafter referred to as “magnification component”) generated due to lens precision (magnification) is calculated (S704). For this reason, first, among the four OLEDs 320 (# 6, # 51, # 60 and # 96) on a predetermined circumference centered on the optical axis for each lens 400, # 6 and # 96 in the main scanning direction The positional deviation amounts De and Df between the reference positions 602 and 605 and the detection positions 612 and 615 are calculated. Further, for # 51 and # 60, positional deviation amounts Dc and Dd between the reference positions 603 and 604 and the detection positions 613 and 614 in the sub-scanning direction are calculated.

  Subtracting the offset amount from the misregistration amounts Dc and Dd in the sub-scanning direction and subtracting the offset amount Δx from the misregistration amounts De and Df in the main scanning direction, # 6, # 51, # 60 and # The power component of 96 OLEDs 320 can be calculated.

# 6: Dcl = Dc-Δy (1)
# 51: Ddl = Dd-Δy (2)
# 60: Del = De-x x (3)
# 96: Dfl = Df-Δx (4)
The magnification components other than the five representative points can be estimated by linear interpolation using the magnification components of the five representative points. Therefore, using the magnification components Dcl, Ddl, Del and Dfl, the magnification component per unit length on the outer peripheral surface of the photosensitive drum 101 (hereinafter referred to as "unit component") is calculated (S705).

  Specifically, a unit component in the main scanning direction and a unit component in the sub-scanning direction in each quadrant from the first quadrant to the fourth quadrant are calculated as in the following equation.

First quadrant Main scanning direction: (Df-Δx) ÷ (Db × 40) (5)
Sub-scanning direction: (Dc-Δy) ÷ (Da × 4) (6)
Second quadrant Main scanning direction: (De−Δx) ÷ (Db × 50) (7)
Sub-scanning direction: (Dc-Δy) ÷ (Da × 4) (8)
Third quadrant main scanning direction: (De−Δx) ÷ (Db × 50) (9)
Sub-scanning direction: (Dd−Δy) ÷ (Da × 5) (10)
Fourth quadrant Main scanning direction: (Df-Δx) ÷ (Db × 40) (11)
Sub-scanning direction: (Dd-Δy) ÷ (Da × 5) (12)
Here, as shown in FIG. 6B, the unit length in the sub scanning direction is the interval Da of the OLED 320 in the sub scanning direction, and the unit length in the main scanning direction is the interval D b of the OLED 320 in the main scanning direction . In the present embodiment, Db is 21.2 μm.

Using these unit components and offset components Δx and Δy, it is possible to calculate a correction value for correcting the deviation of the exposure position for each of the OLEDs 320 corresponding to the master mold according to the distance from the lens 400. it can. For example, as shown in FIG. 8A, at the exposure position of the OLED 320 (# 7, # 17, # 27, etc.) in the third row at the staggered position, the distance from the optical axis in the sub scanning direction is Da × 5-3) = Da × 2 (13)
Therefore, this is a unit component in the sub scanning direction in the first and second quadrants (Dc-.DELTA.y) .varies. (Da.times.4) (14)
When you multiply
(Dc−Δy) × 2/4 (15)
It can be estimated.

Similarly, for the magnification component of the OLED 320 (# 4, # 14, # 24, etc.) of the seventh row in the sub scanning direction, the distance from the optical axis in the sub scanning direction is Da × (7−5) = Da × 2. (16)
Therefore, this is a unit component in the subscanning direction in the third and fourth quadrants (Dd-.DELTA.x) .varies. (Da.times.5) (17)
When you multiply
(Dd−Δy) × 2/5 (18)
It can be estimated.

Further, for the magnification component of the correction value in the main scanning direction, for example, as shown in FIG. 8B, the magnification component of the correction value in the main scanning direction is the same as that in the main scanning direction at the exposure position of the OLED 320 # 1. The distance from the optical axis is Db × (56−1) = Da × 55 (19)
Therefore, this is a unit component in the main scanning direction in the second and third quadrants (De−Δx) ÷ (Db × 50) (20)
When you multiply
(De−Δx) × 11/10 (21)
It can be estimated.

Similarly, for the magnification component of # 100 OLED 320 in the main scanning direction, the distance from the optical axis in the main scanning direction is Db × (100−56) = Da × 44 (22)
Therefore, this can be expressed as a unit component in the main scanning direction in the first and fourth quadrants (Df-.DELTA.x) D (Db × 40) (23)
When you multiply
(Df−Δx) × 11/10 (24)
It can be estimated.

  In this manner, after determining the magnification component of the correction value of each OLED 320, the offset component is audited in each of the main scanning direction and the sub scanning direction, and the correction value is calculated (S706). The correction value of each OLED 320 is a value obtained by adding the magnification component in the main scanning direction to the offset component Δx in the main scanning direction, and the value obtained by adding the magnification component in the subscanning direction to the offset component Δy in the subscanning direction . FIG. 9 and FIG. 10 are tables showing correction values in the main scanning direction and the sub scanning direction for all of the OLEDs # 1 to # 100.

  Of the 100 OLEDs 320 collected by the lens 400 at the same position in the master mold, the OLEDs 320 located at the same position with respect to the lens 400 correct the deviation of the exposure position using the same correction value in the table of FIG. can do. In other words, the OLEDs 320 in the same phase with respect to the period of the master mold can correct the misalignment using the same correction value.

  Specifically, for the lens 400 located at the m-th row and the n-th column of the multi-lens array 201, the remainder n 'obtained by dividing n by 5 is determined, and the positional deviation is performed in the same manner as the lens 400 at the m-th row and the n' It suffices to make corrections.

Thereafter, the calculated correction value for each of the OLEDs 320 is stored (S 707), and the process ends.
(1-6) Correction of Exposure Position Next, correction of the exposure position will be described.

  The deviation of the exposure position is corrected by correcting the light emission timing according to the correction value for each of the OLEDs 320.

  For example, with regard to the OLED 320 in which the positional deviation occurs on the upstream side in the main scanning direction, the positional deviation in the main scanning direction is eliminated by shifting the image data in the main scanning direction by a period corresponding to the correction value (the positional deviation). be able to. On the contrary, for the OLED 320 in which the positional deviation occurs on the downstream side in the main scanning direction, the positional deviation in the main scanning direction can be eliminated if the light emission timing is advanced by a period corresponding to the correction value (the positional deviation). .

  The same applies to the sub scanning direction, and for the OLED 320 in which a positional deviation occurs on the upstream side in the sub scanning direction, the positional deviation in the sub scanning direction is delayed by delaying the light emission timing by a period corresponding to the correction value (the positional deviation). Can be eliminated. On the contrary, for the OLED 320 in which the positional deviation occurs on the downstream side in the sub scanning direction, the positional deviation in the sub scanning direction can be eliminated if the light emission timing is advanced by a period corresponding to the correction value (the positional deviation). .

By thus eliminating the deviation of the exposure position, distortion of the printed image can be prevented.
(1-7) Reference value for performing correction As described above, in the present embodiment, the number of correction values to be stored in the sense that the correction value needs to be determined for only one cycle of the master mold. The required storage capacity can be reduced.

  However, two corrections in the main scanning direction and the sub-scanning direction for each of 100 OLEDs 320 for each lens 400 of the size of the master mold (15 in the third embodiment × 15 rows in this embodiment) Further compression of the amount of data to be stored is desirable because the values must be stored.

  Therefore, the average value of each of the 15 offset components in the main scanning direction and the sub scanning direction detected for 15 lenses 400 equivalent to the master mold is calculated as a reference value, and is substituted for the offset components Δx and Δy. If the reference value is used, the memory capacity can be reduced because it is not necessary to store the offset components Δx and Δy.

  Further, instead of the average value of the offset components, the offset components Δx and Δy related to the lens closest to the portion fixing the optical writing device 100 to the main body of the image forming device 1 may be used as the reference value. In this way, the reference value is stabilized, so that the arithmetic circuit for calculating the reference value can be simplified to reduce the cost.

  Also, the arrangement of the OLED 320 is not limited to the staggered arrangement, but may be arranged in a line or in any block.

The drive current source, the sample hold circuit, and the shift register may be formed by a single crystal silicon driver IC instead of the TFT. Furthermore, the same effect can be obtained by applying the present embodiment also to the optical writing device 100 configured not to use the sample and hold circuit.
[2] Second Embodiment Next, a second embodiment of the present invention will be described.

  The image forming apparatus 1 and the optical writing apparatus 100 according to the present embodiment have a configuration substantially in common with the image forming apparatus 1 and the optical writing apparatus 100 according to the first embodiment, while the master mold The difference in that the deviation of the exposure position is detected only for any lens 400 among the plurality of lenses 400 molded using the above, and the detection result is diverted to the other lenses 400 to perform positional deviation correction. There is. The following description focuses on the differences.

  In the present specification, the same reference numerals are given to members and the like common to the embodiments.

  The shift amount of the exposure position for each lens 400 is correlated with the transferability of the mold used for molding the lens 400. The transferability of the mold is influenced by factors such as temperature distribution and pressure distribution during molding, and residual stress distribution after molding. For example, when the temperature distribution, pressure distribution or residual stress distribution after molding is as shown by the graph 1000 in FIG. 11A, the graph 1000 extends from the main scanning position Pa to Pe, The slope of the graph 1000 changes rapidly at the main scanning positions Pb, Pc and Pd.

  On the other hand, since the change of the slope of the graph 1000 is relatively small between the main scanning positions Pa and Pb, between Pb and Pc, between Pc and Pd, and between Pd and Pe, the graph 1000 should be linearly interpolated. Can. That is, as shown in FIG. 11B, if the shift amount of the exposure position is detected for the lens 400 located at the main scanning positions Pa, Pb, Pc, Pd and Pe, the complementation operation using the detected shift amount The deviation amount at other main scanning positions can be estimated by

For example, offset components Δx and Δy related to the lens 400 at the main scanning position P between the main scanning positions Pa and Pb are offset components Δxa, Δya, Δxb and Δ related to the main scanning positions Pa and Pb. With yb
Δx = {Δxa × (Pb−P) + Δxb × (P−Pa)} ÷ (Pb−Pa) (25)
Δy = {Δya × (Pb−P) + Δyb × (P−Pa)} ÷ (Pb−Pa) (26)
It can be estimated as The same applies to the magnification component.
[3] Third Embodiment Next, a second embodiment of the present invention will be described.

  The image forming apparatus 1 and the optical writing device 100 according to the present embodiment have a configuration substantially in common with the image forming device 1 and the optical writing device 100 according to the first embodiment, while the image forming apparatus The difference is that the positional deviation amount of the exposure position is detected before the optical writing device 100 is attached to 1. The following description focuses on the differences.

  In the present embodiment, before the optical writing device 100 is incorporated into the image forming apparatus 1, the amount of positional deviation is measured for each lens 400 for all the molds used for molding the multi-lens array 201, and the positional deviation component is calculated. It is calculated and stored in the ROM 502 or the HDD 504 of the control unit 150.

  After the optical writing device 100 is incorporated into the image forming apparatus 1, detection and correction of misalignment are performed in substantially the same manner as in FIG. However, in steps S 701 to S 705, the displacement component is calculated only for the lens (hereinafter, referred to as “representative lens”) 400 closest to the portion where the optical writing device 100 is fixed to the image forming device 1.

In step S706, first, the positional deviation component calculated for the representative lens 400 is compared with the positional deviation component stored in advance to obtain a difference. For the lenses 400 other than the representative lens 400, after correcting the misregistration component stored in advance using the difference obtained for the representative lens 400, the misregistration correction is performed by the complementation operation using the corrected misregistration component. Do.
[4] Modifications Although the present invention has been described above based on the embodiment, it goes without saying that the present invention is not limited to the above embodiment, and the following modifications can be implemented. .
(4-1) In the above embodiment, although the case of detecting the positional deviation amount using the line sensor 160 has been described as an example, it goes without saying that the present invention is not limited to this, and instead of this, the following You may do so.

  For example, as illustrated in FIG. 12, a so-called PP (Product Print) machine is provided with an in-line sensor 1102 as an imaging unit in the vicinity of a sheet discharge port 1101 for image stabilization processing such as gradation correction. Instead of the line sensor 160 according to the above embodiment, the in-line sensor 1102 may be used to detect the positional deviation by transferring a toner image for detecting the positional deviation and capturing an image of the recording sheet on which the toner image is fixed.

In this way, since it is not necessary to provide the line sensor 160 for each image forming station 110, cost reduction and downsizing of the apparatus can be achieved.
(4-2) In the above embodiment, the case where the exposure position is corrected by correcting the light emission timing of the OLED 320 has been described as an example, but it goes without saying that the present invention is not limited to this. It may be as follows.

  For example, the light amount may be corrected in accordance with the shift amount of the exposure position. As shown in FIG. 13, the case where the detected exposure position 1220 deviates by Δh in the main scanning direction and Δv in the sub scanning direction from the exposure position 1200 when there is no positional deviation will be described as an example. If the detected exposure position 1220 deviates from the exposure position 1200 in the case of no positional deviation, the exposure position 1220 is surrounded by four exposure positions 1201, 1210 and 1211 including the exposure position 1200.

The gradation value T for exposing the exposure position 1220 is set to pixels P (i: j), P (i: j-1), P (i + 1: j) and P (i: j) of the exposure positions 1200, 1201, 1210 and 1211. Assuming that the gradation values of i + 1: j-1) are T (i: j), T (i: j-1), T (i + 1: j) and T (i + 1: j-1), the positional shift amount Δh , And by linear interpolation based on Δv,
T = {T'1 * (Db- [Delta] h) + T'2 * [Delta] h} ÷ Db (27)
It becomes. Note that
T'1 = {T (i: j) * (Da- [Delta] v) + T (i: j-1) * [Delta] v} ÷ Da (28)
T'2 = {T (i + 1: j) * (Da- [Delta] v) + T (i + 1: j-1) * [Delta] v} ÷ Da (29)
It is.

  Also in this case, it is possible to suppress the image quality deterioration due to the shift of the exposure position.

Note that, since the linear interpolation process acts as a local averaging filter, edge enhancement processing may be further performed on the tone value obtained by the linear interpolation process.
(4-3) In the above embodiment, although the case of using one type of master mold was described as an example, it goes without saying that the present invention is not limited to this, and a plurality of types of master molds are combined to form a multi The lens array 201 may be molded. In this case, if the positional deviation is detected for each type of master mold and the positional deviation component is calculated, the positional deviation component is also used for the lens 400 of the other part molded using the same master mold. The exposure position can be corrected using this.
(4-4) In the above embodiment, although the case where the light emitting element is the OLED 320 has been described as an example, it is needless to say that the present invention is not limited to this, and light of line optical type using the multilens array 201 If it is a writing device, the present invention can be applied to obtain the effect.
(4-5) In the above embodiment, the case where the image forming apparatus 1 is a tandem type color printer has been described as an example, but it goes without saying that the present invention is not limited to this, and color printers other than the tandem type It may be a monochrome printer. The present invention may be applied to a single function machine such as a copying machine having a document reading function or a facsimile machine having a facsimile communication function, or a multi-function peripheral (MFP) having these functions. You can get the effect of

  The optical writing apparatus and the image forming apparatus according to the present invention are useful as an apparatus capable of detecting a shift in exposure position.

1 ...................................................... Image forming apparatus 100 ................................................ Optical writing apparatus 100 ...................... ......................... Photosensitive drum 150 ................................................... Control unit 160 .................... ............ Line sensor 201 ...................................... Multilens array 320 ...................................................... OLED
400....... ........ Inline sensor Da... Interval Db ..... Interval Dc, Dd, De, Df of the OLED 320 in the main scanning direction ........... Position shift amount Δx, Δy .......... Position shift amount Offset component Dcl, Ddl, Del, Dfl ... Magnification component of displacement amount

Claims (13)

An optical writing device comprising a plurality of sets of a plurality of non-single-crystal light emitting means and a lens for focusing the light emitted from the plurality of non-single-crystal light emitting means, the plurality of lenses constituting a lens array. ,
A detection unit that detects an exposure position at which light emitted from a part of the non-single-crystal light emitting units of the plurality of non-single-crystal light emitting units is exposed on the imaging surface;
Calculating means for calculating an amount of positional deviation from a reference position, which is a target exposure position, of the exposure position detected by the detection means;
From the reference position of the exposure position of the non-single-crystal light emission means other than the one portion of the non-single-crystal light emission means using the positional shift amount calculated by the calculation means for each set of exposure positions detected by the detection means. Estimation means for estimating the amount of displacement;
An optical writing apparatus comprising: correction means for correcting an exposure position for all of the plurality of sets using the positional deviation amount calculated by the calculation means and the positional deviation amount estimated by the estimation means. The lens array is configured by arranging a plurality of lens groups,
Each lens group is molded using a common mold,
The detection means detects the exposure position for at least one set of only one lens group among the plurality of lens groups,
The correcting means, for lenses corresponding to the lens groups formed positively in the common mold, corresponds to the positional deviation amount calculated by the calculating means for the one lens group and the positional deviation amount estimated by the estimating means. The optical writing device according to claim 1, wherein the exposure position is corrected using. At least one set of the plurality of non-single-crystal light emitting means and the lens from the plurality of sets according to one or more of the temperature distribution, the pressure distribution, and the stress distribution after molding when forming the lens array. Is selected
The correction means is, for the at least one set, a temperature distribution, a pressure distribution, and a shape after molding of the lens array from the positional deviation amount calculated by the calculation means and the positional deviation amount estimated by the estimation means. The optical writing device according to claim 1, wherein the exposure position is corrected in accordance with one or more of the stress distributions in (1). The detection means detects an exposure position on an imaging surface in a state where the optical writing device is incorporated in an image forming apparatus,
The correction means is
Preliminary storage means for storing an amount of positional deviation expected for each lens in a state in which the optical writing device is not incorporated in an image forming apparatus for two or more lenses molded by a mold for molding the lens array Have
According to the positional deviation amount calculated by the calculating means, the positional deviation amount stored in the preliminary storage means is changed, and using the positional deviation amount, a lens other than the at least one set of the two or more lenses The optical writing device according to claim 1, wherein the exposure position is corrected. The calculation means is a displacement amount of the exposure position detected by the detection means from the reference position of the non-single-crystal light emission means of which the reference position is closest to the optical axis of the lens among the plurality of non-single crystal light emission means Calculated as the offset component,
The optical writing device according to any one of claims 1 to 4, wherein the correction means corrects an exposure position according to the offset component. The plurality of non-single-crystal light emitting means are arranged in a staggered manner so as to be at mutually different positions in the main scanning direction,
The said detection means detected the said detection means about one non-single-crystal light emission means other than the non-single-crystal light emission means whose said reference position is nearest to the optical axis of the said lens among said several non-single-crystal light emission means The positional deviation amount excluding the main scanning direction component of the offset component from the positional deviation amount from the reference position of the exposure position is calculated as a magnification factor component in the main scanning direction,
The optical writing device according to claim 5, wherein the correction means corrects the exposure position in accordance with a magnification component in the main scanning direction. The plurality of non-single-crystal light emitting means are arranged in a staggered manner so as to be at mutually different positions in the main scanning direction,
Among the plurality of non-single-crystal light emitting units, the calculation unit includes two non-single-crystal light emitting units positioned on both sides of the non-single-crystal light emitting unit closest to the optical axis of the lens in the main scanning direction. And calculating the positional deviation amount excluding the main scanning direction component of the offset component from the positional deviation amount from the reference position of the exposure position detected by the detecting unit as a magnification factor in the main scanning direction,
The optical writing device according to claim 5, wherein the correction means corrects the exposure position in accordance with a magnification component in the main scanning direction. The plurality of non-single-crystal light emitting means are arranged in a staggered manner so as to be at mutually different positions in the main scanning direction,
The calculation means is a single non-single crystal light emission means different from the non-single crystal light emission means having the reference position closest to the optical axis of the lens in the sub scanning direction orthogonal to the main scanning direction among the plurality of non single crystal light emission means With regard to the crystal light emitting means, the positional shift amount excluding the sub scanning direction component of the offset component is calculated as the magnification component in the sub scanning direction from the positional shift amount from the reference position of the exposure position detected by the detecting means.
6. The optical writing device according to claim 5, wherein the correction means corrects the exposure position in accordance with the magnification component in the sub scanning direction. The plurality of non-single-crystal light emitting means are arranged in a staggered manner so as to be at mutually different positions in the main scanning direction,
The calculation means is one of the plurality of non-single-crystal light emission means, wherein the reference position is located on both sides of the non-single-crystal light emission means closest to the optical axis of the lens in the sub scanning direction orthogonal to the main scanning direction. For the non-single-crystal light emitting means, the positional deviation amount obtained by removing the wind scanning direction component of the offset component from the positional deviation amount from the reference position of the exposure position detected by the detecting means is taken as the magnification component in the subscanning direction Calculate
6. The optical writing device according to claim 5, wherein the correction means corrects the exposure position in accordance with the magnification component in the sub scanning direction. The optical writing device according to any one of claims 1 to 9, wherein the non-single crystal light emitting means is an OLED. The plurality of non-single-crystal light emitting means are arranged in a staggered manner so as to be at mutually different positions in the main scanning direction,
The optical writing device according to any one of claims 1 to 10, wherein the at least one set is a set located at an end in the main scanning direction. Compression storage means for storing the average value of the positional deviation amount from the reference position of the exposure position of the emitted light for each non-single crystal light emitting means, and the difference between the positional deviation amount for each non single crystal light emitting means and the average value Equipped with
The optical writing according to any one of claims 1 to 11, wherein the correction means corrects the exposure position using a positional deviation amount calculated from an average value and a difference stored in the compression storage means. apparatus. An image forming apparatus comprising the optical writing device according to any one of claims 1 to 12.

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