JP7003560B2 - Optical writing device and image forming device - Google Patents

Description

The present invention relates to an optical writing device and an image forming device, and more particularly to a technique for detecting a deviation of an exposure position in a line optical type optical writing device.

Conventionally, in an electrophotographic image forming apparatus, an optical scanning type optical writing apparatus that writes light to a photoconductor drum by deflecting the emitted light of a laser diode using a scanning optical system has been used. Due to the structure of the scanning optical system, it is difficult to reduce the size, and it is technically difficult to narrow the beam diameter of the emitted light. Therefore, there is a limit to the miniaturization, cost reduction, and higher resolution of the image forming apparatus equipped with the optical scanning type optical writing device.

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

If a line optical type optical writing device is used, it is easy to reduce the size and cost of both the light source and the lens array, and one for each divided region of the light source by using a light emitting element of microdots. Since the image is formed by the lens, the resolution can be increased. Therefore, if a line optical type optical writing device is installed, it is possible to reduce the size, cost, and resolution of the image forming device.

Japanese Unexamined Patent Publication No. 2008-224957

However, in a line optical type optical writing device, when a multi-lens array (MLA) is used as a lens array, the position of each lens in the mold used for molding the multi-lens and the characteristics of the mold itself are affected. Depending on this, an error may occur in the shape of the lens.

For example, as shown in FIG. 14A, when the emitted light L of the light emitting element 1402 constituting the light source 1401 is exposed on the photoconductor 1404 via the lens 1403, the emitted light L is exposed to the main light direction of the emitted light L. When the optical axis 1403a of the lens 1403 is tilted, the emitted light L irradiates a position on the photoconductor 1404 different from the optical path L'when the optical axis 1403a is not tilted by the optical path offset z.

More specifically, as shown in FIG. 14B, the emitted light L of the light emitting element 1402 is incident on the lens 1403 at an incident angle i equal to the tilt angle of the optical axis 1403a of the lens 1403, and is incident on the lens 1403 at the refraction angle j. It emits inward. After that, the lens 1403 is emitted to the outside at the emission angle i. When the emitted light L is refracted in this way, it is incident on the photoconductor 1404 at a position deviated by the optical path offset z from the optical path L'when the optical axis 1403a is not tilted and the incident angle i is 0 degree.

The larger the tilt angle of the optical axis 1403a, the larger the incident angle i and the refraction angle j, so that the optical path offset z becomes larger. Therefore, if the tilt angle of the optical axis 1403a is different for each lens 1403, the magnitude of the optical path offset z varies.

Further, if the tilt direction of the optical axis is different, the deviation direction of the exposure position is different. FIG. 15 shows an exposure position 1501 by a light emitting element located near the axis and an exposure position 1502 by four light emitting elements located on concentric circles equal to the optical axis when the optical axis of the lens is not tilted. It is a figure which illustrates how 1503, 1504 and 1505 are displaced by the tilt direction of an optical axis.

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

Furthermore, even if the tilt angle and tilt direction of the optical axis are the same, if the magnification differs for each lens due to variations in lens accuracy within the mold, the magnitude of the optical path offset z will vary, resulting in a printed image. There is a problem that distortion occurs.

The present invention has been made in view of the above-mentioned problems, and provides an optical writing device and an image forming device for correcting image distortion caused by characteristic variation between lenses constituting 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 forming an image of the emitted light of the plurality of non-single crystal light emitting means. A plurality of lenses are optical writing devices constituting a lens array, and 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 means for detecting an exposure position where light is exposed on the image formation surface, a calculation means for calculating the amount of displacement of the exposure position detected by the detection means from a reference position which is a target exposure position, and the above-mentioned. For each set in which the exposure position is detected by the detection means, the position of the exposure position of the non-single crystal light emitting means other than the partial non-single crystal light emitting means from the reference position by using the position deviation amount calculated by the calculation means. An estimation means for estimating the deviation amount, and a correction means for correcting the exposure position for all of the plurality of sets by using the position deviation amount calculated by the calculation means and the position deviation amount estimated by the estimation means are provided . The lens array is configured by arranging a plurality of lens groups, and the lenses at positions corresponding to each other have the same optical axis tilt and lens accuracy, and the detection means is the plurality of lens groups. The exposure position was detected for at least one set of only one lens group, and the correction means calculated the lens with the same optical axis tilt and lens accuracy for the one lens group. It is characterized in that the exposure position is corrected by using the misalignment amount and the misalignment amount estimated by the estimation means .

By doing so, the exposure position of the emitted light of the non-single crystal light emitting means is detected, the amount of misalignment of the exposure position due to the variation in the characteristics of the lenses is calculated, and the amount of misalignment is used to determine the exposure position. Since it is corrected, it is possible to correct the distortion of the image.

Further, an optical writing device having a plurality of pairs of a plurality of non-single crystal light emitting means and a lens for forming an image of the emitted light of the plurality of non-single crystal light emitting means, and the plurality of lenses form a lens array. Therefore, for at least one of the plurality of sets, the exposure position where the light emitted from some of the non-single crystal light emitting means among the plurality of non-single crystal light emitting means is exposed on the image formation surface is detected. The calculation is performed for each of the detection means, the calculation means for calculating the amount of positional deviation of the exposure position detected by the detection means from the reference position which is the target exposure position, and the set for which the exposure position is detected by the detection means. Using the misalignment amount calculated by the means, the estimation means for estimating the misalignment amount from the reference position of the exposure position of the non-single crystal light emitting means other than the partial non-single crystal light emitting means, and the calculation means are calculated. The detection means comprises a correction means for correcting the exposure position for all of the plurality of sets by using the misalignment amount and the misalignment amount estimated by the estimation means, and the detection means uses the optical writing device as an image forming device. A pair of a representative lens, which is the lens closest to the fixed portion, and a non-single crystal light emitting means for forming an image of emitted light by the representative lens, on the image forming surface in a state where the optical writing device is incorporated in the image forming device. The correction means detects the exposure position in the lens array, and the correction means is used for each lens of two or more lenses molded by a mold for molding the lens array in a state where the optical writing device is not incorporated in the image forming device. It has a preliminary storage means for storing the expected amount of misalignment, and the difference between the amount of misalignment calculated by the calculation means and the amount of misalignment expected for the representative lens stored in the preliminary storage means. The feature is that the exposure position of the two or more lenses other than the representative lens is corrected by using the position shift amount obtained by changing the position shift amount stored by the preliminary storage means. To do .

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

Here, the plurality of non-single crystal light emitting means are staggeredly arranged so as to be at different positions in the main scanning direction, and the calculation means is the reference position among the plurality of non-single crystal light emitting means. With respect to 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 scan of the offset components is based on the amount of misalignment of the exposure position detected by the detecting means from the reference position. It is more preferable that the amount of misalignment 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 means are staggered so as to be located at different positions in the main scanning direction, and the calculation means is among the plurality of non-single crystal light emitting means in the main scanning direction. From the amount of misalignment of the exposure position detected by the detection means from the reference position for the two non-single crystal light emitting means whose reference positions are located on both sides of the non-single crystal light emitting means closest to the optical axis of the lens. The amount of misalignment of the offset components excluding the main scanning direction component may be calculated as a magnification component in the main scanning direction, and the correction means may correct the exposure position according to the magnification component in the main scanning direction. ..

Further, the plurality of non-single crystal light emitting means are staggered so as to be located at different positions in the main scanning direction, and the calculation means is used in the main scanning direction among the plurality of non-single crystal light emitting means. In the orthogonal sub-scanning direction, one non-single crystal light emitting means whose reference position is different from the non-single crystal light emitting means closest to the optical axis of the lens is displaced from the reference position of the exposure position detected by the detecting means. The amount of misalignment of the offset component excluding the sub-scanning direction component is calculated as the magnification component in the sub-scanning direction from the amount, and the correction means corrects the exposure position according to the magnification component in the sub-scanning direction. You may.

Further, the plurality of non-single crystal light emitting means are staggered so as to be located at different positions in the main scanning direction, and the calculation means is used in the main scanning direction among the plurality of non-single crystal light emitting means. From the reference position of the exposure position detected by the detection means for the two non-single crystal light emitting means whose reference positions are located on both sides of the non-single crystal light emitting means closest to the optical axis of the lens in the orthogonal sub-scanning directions. The amount of misalignment excluding the sub- scanning direction component from the misalignment amount of is calculated as a magnification component in the sub-scanning direction, and the correction means measures the exposure position according to the magnification component in the sub-scanning direction. May be corrected.

Further, it is desirable that the non-single crystal light emitting means is an OLED.

Further, the plurality of non-single crystal light emitting means are staggered so as to be located at different positions in the main scanning direction, and at least one set thereof may be a set located at an end portion in the main scanning direction. good.

Further, compression for storing the average value of the amount of misalignment of the exposure light of the emitted light for each non-single crystal light emitting means from the reference position, and the difference between the amount of misalignment for each non-single crystal light emitting means and the average value. The storage means may be provided, and the correction means may correct the exposure position by using the position deviation amount calculated from the average value and the difference stored in the compression storage means.

Further, the image forming apparatus according to the present invention is characterized by including the optical writing apparatus according to the present invention.

It is a figure which shows the main structure of the image forming apparatus which concerns on 1st Embodiment. (A) is a diagram showing the main configuration of the optical writing device 100, and (b) is a schematic plan view of the OLED panel unit 200, a sectional view taken along the line AA'and a sectional view taken along the line CC'. 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 Cairo 214, and (b) is a circuit diagram showing the configuration of the selection circuit 301 and the light emitting block 302. It is a block diagram which shows the main structure of ASIC 220. It is a block diagram which shows the main structure of the control part 150. (A) is a plan view showing an arrangement of multi-lenses, (b) is a plan view showing an arrangement of pixels corresponding to one lens, and (c) is a plan view illustrating an exposure position. It is a flowchart which shows the operation of the image forming apparatus 1. Of the magnification components of the exposure position shift amount, (a) is a graph showing the magnification component in the sub-scanning direction, and (b) is a graph showing the magnification component in the main scanning direction. (A) is a table showing the amount of deviation of the exposure position of the pixels from the first column to the third column, and (b) is a table showing the amount of deviation of the exposure position of the pixels from the fourth column to the fifth column. be. (A) is a table showing the amount of deviation of the exposure position of the pixels from the 6th column to the 8th column, and (b) is a table showing the amount of deviation of the exposure position of the pixels from the 9th column to the 10th column. be. Regarding the second embodiment, (a) is a graph illustrating the temperature distribution at the time of molding, the pressure distribution or the residual stress distribution after molding, and (b) is the lens 400 for which the deviation amount of the exposure position should be detected. It is an exemplary plan view. It is a figure which shows the main structure of the image forming apparatus 1 which concerns on a modification. It is a figure which illustrates the positional relationship between the exposure position when there is no misalignment, and the exposure position when there is a misalignment. (A) is a diagram for explaining the configuration of a general optical writing device, and (b) is a diagram for explaining the deviation of the exposure position due to the inclination of the optical axis 1403a of the lens 1403. It is a figure which illustrates the relationship between the tilt direction of the optical axis of a lens, and the deviation direction of an exposure position.

Hereinafter, embodiments of the optical writing device and the image forming device according to the present invention will be described with reference to the drawings.
[1] First Embodiment The image forming apparatus according to the first embodiment of the present invention corrects image distortion in an optical writing apparatus using a multi-lens array molded by repeatedly using a master mold. Therefore, it is characterized in that image distortion is detected only in 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 Device 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 color printer, and is an image forming toner images of yellow (Y), magenta (M), cyan (C), and black (K) colors. It is equipped with forming stations 110Y, 110M, 110C and 110K. The image forming stations 110Y, 110M, 110C and 110K have photoconductor drums 101Y, 101M, 101C and 101K rotating in the direction of arrow A.

Around the photoconductor 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 are sequentially arranged along the outer peripheral surface. Primary transfer rollers 104Y, 104M, 104C and 104K and cleaning devices 105Y, 105M, 105C and 105K are arranged.

Further, line sensors 160Y, 160M, 160C and 160K are arranged on the downstream side of the developing devices 103Y, 103M, 103C and 103K in the rotation direction of the photoconductor drums 101Y, 101M, 101C and 101K. The line sensors 160Y, 160M, 160C and 160K detect at which position in the main scanning direction the toner is attached on the outer peripheral surface of the photoconductor 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 sufficiently short time intervals, 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 photoconductor drums 101Y, 101M, 101C and 101K. The optical writing devices 100Y, 100M, 100C and 100K are so-called OLED-PH (Organic Light Emitting Diode-Print Head), and expose the outer peripheral surfaces of the photoconductor drums 101Y, 101M, 101C and 101K to perform an electrostatic latent image. To form.

The developing devices 103Y, 103M, 103C and 103K supply toner of each color of YMCK to develop an electrostatic latent image and form a toner image of each color of YMCK. The primary transfer rollers 104Y, 104M, 104C and 104K electrostatically transfer the toner image carried by the photoconductor drums 101Y, 101M, 101C and 101K to the intermediate transfer belt 106 (primary transfer).

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

The intermediate transfer belt 106 is an endless belt, which is stretched on the secondary transfer roller pair 107 and the driven rollers 108 and 109, and rotates in the direction of arrow B. By performing the primary transfer in accordance with this rotational running, the toner images of each color of YMCK are superimposed on each other to form a color toner image. The intermediate transfer belt 106 rotates while carrying the color toner image to convey the color toner image to the secondary transfer nip of the secondary transfer roller pair 107.

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

The recording sheet S is conveyed to the fixing device 130 with the color toner image carried, and after the color toner image is heat-fixed, it is discharged onto the paper ejection 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 device such as a PC (Personal Computer), the control unit 150 controls the operation of the image forming apparatus 1 to execute image forming.
(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 has a configuration in which the OLED panel unit 200 and the multi-lens array 201 are supported by the holder 202, and the emitted light L of the OLED panel unit 200 is supported by the multi-lens array. The light is focused on the outer peripheral surface of the photoconductor drum 101 by 201. The cables and the like for connecting the optical writing device 100 and the other devices of the image forming device 1 are 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 the glass substrate 210, and 15,000 OLEDs (not shown) are arranged in a line at a pitch of 21.2 μm (1200 dpi) along the main scanning direction. ing. Although the line-shaped OLEDs are arranged in a staggered manner in the present embodiment, they may be arranged in a row.

Further, the substrate surface of the glass substrate 210 on which the OLED is arranged 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 with dry nitrogen or the like sealed so as not to come into contact with the outside air. In addition, for hygroscopicity, a hygroscopic agent may be encapsulated together in the sealing region. The sealing plate 211 may be, for example, sealed glass or may be made of a material other than glass.

The driver IC 212 is mounted outside the sealing region of the glass substrate 210. The ASIC (Application Specific Integrated Circuit) 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 a digital luminance signal into an analog luminance signal (hereinafter, simply referred to as “luminance signal”) and inputs it to the drive circuit for each OLED. The drive circuit generates an OLED drive current according 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, 15,000 OLEDs 320 are grouped into 150 light emitting blocks 302, 100 each. Further, the driver IC 212 has 150 current DACs (Digital to Analogue Converters) 300 built-in, and each has a one-to-one correspondence with the light emitting block 302. 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 arranged on each circuit from the current DAC 300 to the light emitting block 302. Further, a reset circuit 303 is connected on the circuit from the driver IC 212 to the selection circuit 301. Each current DAC 300 sequentially outputs a luminance signal to 100 OLEDs 320 under its control by so-called rolling drive. One current DAC 300 is time-shared by 100 OLEDs 320 contained in the corresponding light emitting 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 and one drive 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 selective TFTs 312, and turns on the selected TFTs 312 in sequence. The source terminal of the selective 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 selective TFT 312, the output current of the current DAC 300 flows to the first terminal of the capacitor 321 and charges are accumulated in the capacitor 321. The charge stored in the capacitor 321 is retained until it is 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 anode terminal of the OLED 320 is connected to the drain terminal of the drive TFT 322, 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 the drive current supplied to the OLED 320, and the drive TFT 322 sets the drive current according to the luminance signal voltage held between the first and second terminals of the capacitor 321 to the OLED 320. 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 the 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 in 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 wiring from the current DAC 300 to the capacitor 321 is reset to the reset potential. The reset potential may be a Vdd potential or a ground potential, and an appropriate potential may be selected. Further, in the present embodiment, the case where the OLED 320 does not emit light in the reset state will be described, but the OLED 320 may emit light in the reset state.

In the present embodiment, the case where the drive TFT 322 is a p-channel is described as an example, but 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 placed under the control of the driver IC 212, but instead of this, the reset circuit 303 may be built in the driver IC 212. .. Further, the function of the reset circuit 303 may be realized by changing the polarity of the current output by the current DAC at the time of reset and at the time of writing. Further, instead of the reset TFT 340, a switching element other than the 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 has 15,000 dot counters 403 corresponding to each OLED 320. A predetermined count value is added to the dot counter 403 each time the corresponding OLED 320 issues.

The drive current correction unit 401 refers to the dot counter 403 for each OLED 320, and corrects the drive current amount each time the counter value reaches the dot count threshold value. When 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 degree of deterioration for each OLED 320. Further, the in-machine temperature of the image forming apparatus 1 may be measured by using a temperature sensor, and the drive current amount may be corrected by using the 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 CPU (Central Processing Unit) 501, a ROM (Read Only Memory) 502, a RAM (Random Access Memory) 503, and the like, and the power is turned on to the image forming apparatus 1. Then, the CPU 501 reads the boot program from the ROM and starts the boot program, and executes the OS (Operating System) and the control program read from the HDD (Hard Disk Drive) 504 using the RAM 503 as a working storage area.

Further, the control unit 150 controls various operation timings of the image forming apparatus 1 by using the timer 505, and refers to the detection timing by the sensor. The NIC (Network Interface Card) 506 is used for communicating 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 device, the control unit 150 controls each unit of the image forming apparatus 1 to execute an image forming process according to the printing job.

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

The CPU 501 calculates the number of clocks from the exposure by the optical writing device 100 to the detection of the toner image by the line sensor 160 with reference to the clock signal, and the exposure position by the optical writing device 100 is detected by the line sensor 160. By comparing with the time (number of clocks) required to reach the position, the positional deviation of the toner image in the sub-scanning direction can be detected.

Regarding the main scanning direction, if the detection position by the line sensor 160 is compared with the exposure position, the positional deviation of the toner image can be detected.
(1-6) Detection of Exposure Position Next, detection of deviation of the exposure position due to the tilt of the optical axis of the lenses constituting the multi-lens array 201 and the accuracy of the lens will be described.

As shown in FIG. 6A, the multi-lens array 201 includes a 3 row × 50 column lens 400 molded by repeatedly using a 3 row × 5 column master mold 10 times. Therefore, the lens 400 has the same characteristics for every five rows in the main scanning direction, and the same optical axis tilt and lens accuracy are repeated for 10 cycles. Each of the 150 lenses 400 collects the emitted light L of 100 OLEDs 320. As a result, the emitted light L of the 15,000 OLEDs 320 is focused on the outer peripheral surface of the photoconductor drum 101.

As shown in FIG. 6 (b), 100 OLEDs 320 that emit the emitted light L condensed by one lens 400 are staggered in 10 rows × 10 columns on the glass substrate 210. In the figure, numbers # 1 to # 100 are assigned to the OLED 320 in order from the upstream in the main scanning direction.

In order to detect the optical axis tilt of the lens 400 and the deviation of the exposure position due to the lens accuracy, of the 100 lenses 400, the five OLEDs 320 indicated by the white circles in FIG. 6B, that is, the optical axis of the lens 400 ( The # 56 OLED 320 located closest to the optical center) and four located on the circumference centered on the optical axis of the lens 400, which are approximately equal to each other from the optical axis of the lens 400. The OLED 320 (# 6, # 51, # 60 and # 96) is turned on.

The OLEDs 320 of # 6 and # 96 are located at positions sandwiching the optical axis in the main scanning direction, and the OLED320s of # 51 and # 60 are located at positions sandwiching the optical axis in the sub-scanning direction. The emitted light L of these five OLEDs 320 exposes five representative points on the outer peripheral surface of the photoconductor drum 101.

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

In order to detect such a misalignment, the control unit 150 forms a toner image for detecting the misalignment on the outer peripheral surface of the photoconductor drum 101 as shown in FIG. 7 (S701).

In normal image formation, in synchronization with the rotation of the photoconductor drum 101, the OLEDs 320 from the first row to the tenth row light up at different timings for each lens 400, and the outer peripheral surface of the photoconductor drum 101 is illuminated. By exposure, one line of electrostatic latent image is formed.

On the other hand, when detecting the positional deviation of the exposure position, the control unit 150 uniformly charges the outer peripheral surface of the photoconductor drum 101 by the charging device 102 while rotationally driving the photoconductor drum 101. Further, the photoconductor drum 101 is rotationally driven, and when the charged region reaches the exposure position of the optical writing device 100, the exposure is performed with the rotational drive of the photoconductor drum 101 temporarily stopped.

The toner image for misalignment detection is an image of only one line, and as illustrated in FIG. 6B, for each lens 400 of the lens 400 having 3 rows × 5 columns corresponding to one cycle of the master mold. Turn on 5 OLED 320s at a time. The five OLEDs 320 expose a position on the outer peripheral surface of the photoconductor drum 101 according to the position on the glass substrate 210.

Therefore, as illustrated in FIG. 6C, the exposure positions of the five representative points do not always match in the sub-scanning direction. Needless to say, the exposure positions of the five representative points are different from each other in the main scanning direction.

After that, the control unit 150 detects the toner image with the line sensor 160 (S702). Specifically, after forming the electrostatic latent image by exposure, the control unit 150 restarts the rotational drive of the photoconductor drum 101 and develops the electrostatic latent image by the developing device 103. Then, the toner image is repeatedly detected by the line sensor 160 while the photoconductor drum 101 is rotationally driven.

The line sensor 160 is a sensor in which light receiving elements are arranged in a row in the main scanning direction, and can detect at which position in the main scanning direction the toner image is formed from the amount of light received by 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 the toner image is detected.

For example, the control unit 160 refers to the elapsed time (clock number) from restarting the rotational drive of the photoconductor drum 101 after exposure to determine at which position in the sub-scanning direction the toner image is formed. 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. Of the amounts, 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 the misalignment components (offset amount) due to the inclination of the optical axis (S703).

Using the offset components Δx and Δy, a misalignment component (hereinafter referred to as “magnification component”) generated due to lens accuracy (magnification) is calculated (S704). Therefore, of 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 are in the main scanning direction. The misalignment amounts De and Df between the reference positions 602 and 605 and the detection positions 612 and 615 are calculated. For # 51 and # 60, the misalignment 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.

When the offset amount is subtracted from the position shift amounts Dc and Dd in the sub-scanning direction and the offset amount Δx is subtracted from the position shift amounts De and Df in the main scan direction, # 6, # 51, # 60 and # are as shown in the following equation. The magnification component of 96 OLED 320 can be calculated.

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

Specifically, the unit component in the main scanning direction and the unit component in the sub-scanning direction in each quadrant from the first quadrant to the fourth quadrant are calculated by 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－ △ x) ÷ (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 OLEDs 320 in the sub-scanning direction, and the unit length in the main scanning direction is the interval Db of the OLEDs 320 in the main scanning direction. .. In this embodiment, Db is 21.2 μm.

By 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 OLED 320 corresponding to the master mold according to the distance from the lens 400. can. For example, as shown in FIG. 8A, at the exposure position of the OLED320 (# 7, # 17, # 27, etc.) in the third row at the staggered row position, the distance from the optical axis in the sub-scanning direction is Da × (. 5-3) = Da × 2… (13)
Therefore, this is the unit component in the sub-scanning direction in the first quadrant and the second quadrant (Dc−Δy) ÷ (Da × 4)… (14).
Multiply by
(Dc−Δy) × 2/4… (15)
Can be estimated.

Similarly, the magnification component of the OLED 320 (# 4, # 14, # 24, etc.) on the 7th row in the sub-scanning direction has a distance from the optical axis in the sub-scanning direction of Da × (7-5) = Da × 2 ... (16)
Therefore, this is used as the unit component in the sub-scanning direction in the third and fourth quadrants (Dd−Δx) ÷ (Da × 5)… (17).
Multiply by
(Dd−Δy) × 2/5… (18)
Can be estimated.

Regarding 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 in the main scanning direction at the exposure position of the OLED 320 of # 1. The distance from the optical axis is Db × (56-1) = Da × 55… (19)
Therefore, this is the unit component in the main scanning direction in the second quadrant and the third quadrant (De−Δx) ÷ (Db × 50)… (20).
Multiply by
(De－ △ x) × 11/10… (21)
Can be estimated.

Similarly, the magnification component of # 100 OLED 320 in the main scanning direction has a distance from the optical axis in the main scanning direction of Db × (100-56) = Da × 44… (22).
Therefore, this is the unit component in the main scanning direction in the first quadrant and the fourth quadrant (Df−Δx) ÷ (Db × 40)… (23).
Multiply by
(Df－ △ x) × 11/10… (24)
Can be estimated.

In this way, after obtaining the magnification component of the correction value of each OLED 320, the offset component is audited for 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 sub-scanning direction to the offset component Δy in the sub-scanning direction. .. 9 and 10 are tables showing correction values in the main scanning direction and the sub-scanning direction for all OLEDs 320 from # 1 to # 100.

Of the 100 OLEDs 320 that the lens 400 at the same position in the master mold collects, the OLEDs 320 that are 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 that are in the same phase for the period of the master mold can correct the misalignment by using the same correction value.

Specifically, for the lens 400 located in the m-row and n-th column of the multi-lens array 201, the remainder n'by dividing n by 5 is obtained, and the position shift is the same as that of the lens 400 in the m-row and n'th column. You just have to make the correction.

After that, the calculated correction value for each OLED 320 is stored (S707), 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 OLED 320.

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

The same applies to the sub-scanning direction. For the OLED 320 in which the position shift occurs on the upstream side in the sub-scanning direction, the position shift in the sub-scanning direction is performed by delaying the light emission timing by the period corresponding to the correction value (position shift). Can be resolved. On the contrary, for the OLED 320 in which the position shift occurs on the downstream side in the sub-scanning direction, the position shift in the sub-scanning direction can be eliminated by advancing the light emission timing by the period corresponding to the correction value (position shift). ..

By eliminating the deviation of the exposure position in this way, it is possible to prevent distortion of the printed image.
(1-7) Reference value for correction As described above, in the present embodiment, the number of correction values to be memorized in the sense that the correction value needs to be obtained for only one cycle of the master mold. Can be reduced to reduce the required storage capacity.

However, for each lens 400 of the size of the master mold (15 in 3 rows × 5 columns in this embodiment), two corrections of the main scanning direction and the sub-scanning direction are made for each of the 100 OLEDs 320. Since the value must be stored, it is desirable to further reduce the amount of data to be stored.

Therefore, as a reference value, the average value of each of the 15 offset components in the main scanning direction and the sub-scanning direction detected for the 15 lenses 400 corresponding to the master mold is calculated, and the offset components Δx and Δy are replaced with each other. If the reference value is used, it is not necessary to store the offset components Δx and Δy, so that the memory capacity can be reduced.

Further, instead of the average value of the offset components, the offset components Δx and Δy related to the lens closest to the portion where the optical writing device 100 is fixed to the main body of the image forming apparatus 1 may be used as a reference value. By doing so, since the reference value is stable, it is possible to simplify the arithmetic circuit for calculating the reference value and reduce the cost.

Further, it goes without saying that the arrangement of the OLEDs 320 is not limited to the staggered arrangement, and the arrangement may be arranged in a single row or may be arranged in any block.

Further, the drive current source, the sample hold circuit, and the shift register may be configured by a single crystal silicon driver IC instead of being configured by the TFT. Further, the same effect can be obtained by applying the present embodiment to the optical writing device 100 having a configuration that does not use the sample 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 substantially the same configuration as the image forming apparatus 1 and the optical writing apparatus 100 according to the first embodiment, while the master mold. The difference is that the deviation of the exposure position is detected only for one of the plurality of lenses 400 molded using the above, and the detection result is diverted to the other lens 400 to correct the displacement. There is. Hereinafter, the differences will be mainly described.

In this specification, common reference numerals are given to members and the like that are common to the embodiments.

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

On the other hand, since the change in 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 be done. That is, as illustrated in FIG. 11B, if the deviation amount of the exposure position is detected for the lens 400 located at the main scanning positions Pa, Pb, Pc, Pd and Pe, the complementary operation using the detected deviation amount is performed. Can be used to estimate the amount of deviation at other main scanning positions.

For example, the offset components Δx and Δy relating 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)
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.

While the image forming apparatus 1 and the optical writing apparatus 100 according to the present embodiment have substantially the same configuration as the image forming apparatus 1 and the optical writing apparatus 100 according to the first embodiment, the image forming apparatus The difference is that the amount of misalignment of the exposure position is detected before the optical writing device 100 is attached to 1. Hereinafter, the differences will be mainly described.

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

After incorporating the optical writing device 100 into the image forming apparatus 1, the positional deviation is detected and corrected in substantially the same manner as in FIG. 7. However, in steps S701 to S705, the misalignment 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.

Further, in step S706, first, the misalignment component calculated for the representative lens 400 and the misalignment component stored in advance are compared to obtain the difference. For the lens 400 other than the representative lens 400, the misalignment component stored in advance is corrected by using the difference obtained for the representative lens 400, and then the misalignment correction is performed by the complementary operation using the corrected misalignment component. conduct.
[4] Modifications Although the present invention has been described above based on the embodiments, it goes without saying that the present invention is not limited to the above-described embodiments, and the following modifications can be implemented. ..
(4-1) In the above embodiment, the case where the amount of misalignment is detected by using the line sensor 160 has been described as an example, but it goes without saying that the present invention is not limited to this, and instead of this, the following is described. 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 image pickup unit in the vicinity of the sheet ejection 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 transfer the toner image for detecting the misalignment and image the fixed recording sheet to detect the misalignment.

By doing so, it is not necessary to provide the line sensor 160 for each image forming station 110, so that cost reduction and miniaturization 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. You may also do the following:

For example, the amount of light may be corrected according to the amount of deviation of the exposure position. As shown in FIG. 13, a case where the detected exposure position 1220 is deviated 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. When the detected exposure position 1220 deviates from the exposure position 1200 when there is no misalignment, 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 the pixels P (i: j), P (i: j-1), P (i + 1: j) and P (i: j-1) 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 amount of misalignment Δh , Δv-based linear complementation
T = {T'1 x (Db- △ h) + T'2 x △ h} ÷ Db ... (27)
Will be. note that,
T'1 = {T (i: j) × (Da−Δv) + T (i: j-1) × Δv} ÷ Da… (28)
T'2 = {T (i + 1: j) x (Da- △ v) + T (i + 1: j-1) x △ v} ÷ Da ... (29)
Is.

Even in this way, deterioration of image quality due to deviation of the exposure position can be suppressed.

Since the linear interpolation process acts as a local averaging filter, edge enhancement processing may be further applied to the gradation value obtained by the linear interpolation process.
(4-3) In the above embodiment, the case where one type of master mold is used has been described as an example, but 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 misalignment is detected for each type of master mold and the misalignment component is calculated, the misalignment component can be obtained for the lens 400 of the other portion molded using the same master mold. Can be used to correct the exposure position.
(4-4) In the above embodiment, the case where the light emitting element is the OLED 320 has been described as an example, but it goes without saying that the present invention is not limited to this, and the line optical type light using the multi-lens array 201 is used. 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 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. Further, the same applies even if the present invention is applied to a single-function device such as a copying device having a document reading function or a facsimile machine having a facsimile communication function, or a multifunction device (MFP: Multi-Function Peripheral) having these functions. The effect of can be obtained.

The optical writing device and the image forming device according to the present invention are useful as devices capable of detecting the deviation of the exposure position.

1 …………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………… …………………………… Photoreceptor drum 150 ……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………… ………… Line sensor 201 …………………………………… Multi-lens array 320 …………………………………………………… OLED
400 ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………… Interval Db ……………… Offset of OLED320 in the main scanning direction Dc, Dd, De, Df ………………………… Position deviation amount Δx, Δy …………………… Position deviation amount Offset component Dcl, Ddl, Del, Dfl ... Magnification component of the amount of misalignment

Claims (11)

It is an optical writing device having a plurality of pairs of a plurality of non-single crystal light emitting means and a lens for forming an image of the emitted light of the plurality of non-single crystal light emitting means, and the plurality of lenses form a lens array. hand,
For at least one of the plurality of sets, a detection means for detecting an exposure position where light emitted from some of the non-single crystal light emitting means among the plurality of non-single crystal light emitting means is exposed on the image formation surface.
A calculation means for calculating the amount of displacement of the exposure position detected by the detection means from the reference position, which is the target exposure position, and
For each set in which the exposure position is detected by the detection means, the misalignment amount calculated by the calculation means is used from the reference position of the exposure position of the non-single crystal light emitting means other than the partial non-single crystal light emitting means. An estimation method for estimating the amount of misalignment, and
A correction means for correcting the exposure position for all of the plurality of sets by using the position shift amount calculated by the calculation means and the position shift amount estimated by the estimation means is provided.
The lens array is configured by arranging a plurality of lens groups.
The lenses in the corresponding positions of the lens groups have the same optical axis tilt and lens accuracy.
The detection means detects the exposure position for at least one set in only one lens group among the plurality of lens groups.
For lenses having the same optical axis tilt and lens accuracy , the correction means uses the amount of misalignment calculated by the calculation means and the amount of misalignment estimated by the estimation means for the one lens group to determine the exposure position. An optical writing device characterized by correction. It is an optical writing device having a plurality of pairs of a plurality of non-single crystal light emitting means and a lens for forming an image of the emitted light of the plurality of non-single crystal light emitting means, and the plurality of lenses form a lens array. hand,
For at least one of the plurality of sets, a detection means for detecting an exposure position where light emitted from some of the non-single crystal light emitting means among the plurality of non-single crystal light emitting means is exposed on the image formation surface.
A calculation means for calculating the amount of displacement of the exposure position detected by the detection means from the reference position, which is the target exposure position, and
For each set in which the exposure position is detected by the detection means, the misalignment amount calculated by the calculation means is used from the reference position of the exposure position of the non-single crystal light emitting means other than the partial non-single crystal light emitting means. An estimation method for estimating the amount of misalignment, and
A correction means for correcting the exposure position for all of the plurality of sets by using the position shift amount calculated by the calculation means and the position shift amount estimated by the estimation means is provided.
The detection means writes light about a set of a representative lens, which is the lens closest to the portion where the light writing device is fixed to the image forming device, and a non-single crystal light emitting means for forming an image of emitted light by the representative lens. Detects the exposure position on the image formation surface when the device is incorporated in the image forming device.
The correction means
Preliminary storage means for storing the expected amount of misalignment for each lens in a state where the optical writing device is not incorporated in the image forming device for two or more lenses molded by the mold for molding the lens array. Have,
The amount of misalignment stored by the pre-storage means is determined according to the difference between the amount of misalignment calculated by the calculation means and the amount of misalignment expected for the representative lens stored by the pre-storage means. An optical writing device, characterized in that the exposure position of a lens other than the representative lens among the two or more lenses is corrected by using the changed amount of misalignment. The calculation means is an amount of displacement of the exposure position detected by the detection means from the reference position of the non-single crystal light emitting means whose reference position is closest to the optical axis of the lens among the plurality of non-single crystal light emitting means. Is calculated as an offset component,
The optical writing device according to claim 1 or 2 , wherein the correction means corrects an exposure position according to the offset component. The plurality of non-single crystal light emitting means are staggered so as to be located at different positions in the main scanning direction.
The calculation means detected one non-single crystal light emitting means other than the non-single crystal light emitting means whose reference position is closest to the optical axis of the lens among the plurality of non-single crystal light emitting means. The amount of misalignment of the exposure position from the reference position, excluding the main scanning direction component from the offset components, is calculated as the magnification component in the main scanning direction.
The optical writing device according to claim 3 , wherein the correction means corrects an exposure position according to a magnification component in the main scanning direction. The plurality of non-single crystal light emitting means are staggered so as to be located at different positions in the main scanning direction.
The calculation means is two non-single crystal light emitting means having the reference position located on both sides of the non-single crystal light emitting means closest to the optical axis of the lens in the main scanning direction among the plurality of non-single crystal light emitting means. With respect to, the amount of misalignment of the exposure position detected by the detection means from the reference position, excluding the main scanning direction component of the offset components, is calculated as a magnification component in the main scanning direction.
The optical writing device according to claim 3 , wherein the correction means corrects an exposure position according to a magnification component in the main scanning direction. The plurality of non-single crystal light emitting means are staggered so as to be located at different positions in the main scanning direction.
The calculation means is one of the plurality of non-single crystal light emitting means whose reference position is different from the non-single crystal light emitting means closest to the optical axis of the lens in the sub-scanning direction orthogonal to the main scanning direction. For the crystal light emitting means, the amount of misalignment of the exposure position detected by the detection means from the reference position, excluding the sub-scanning direction component from the offset component, is calculated as a magnification component in the sub-scanning direction.
The optical writing device according to claim 3 , wherein the correction means corrects an exposure position according to a magnification component in the sub-scanning direction. The plurality of non-single crystal light emitting means are staggered so as to be located at different positions in the main scanning direction.
The calculation means is located on both sides of the non-single crystal light emitting means whose reference position is 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 emitting means. For the two non-single crystal light emitting means, the amount of misalignment of the exposure position detected by the detection means from the reference position, excluding the sub- scanning direction component of the offset components, is used as the magnification component in the sub-scanning direction. Calculate and
The optical writing device according to claim 3 , wherein the correction means corrects an exposure position according to a magnification component in the sub-scanning direction. The optical writing device according to any one of claims 1 to 7 , wherein the non-single crystal light emitting means is an OLED. The plurality of non-single crystal light emitting means are staggered so as to be located at different positions in the main scanning direction.
The optical writing device according to any one of claims 1 to 8 , wherein the at least one set is a set located at an end portion in the main scanning direction. Compressed storage means for storing the average value of the amount of misalignment of the exposure position of the emitted light for each non-single crystal light emitting means from the reference position, and the difference between the amount of misalignment 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 9 , wherein the correction means corrects an exposure position by using a position shift amount calculated from an average value and a difference stored in the compression storage means. Device. An image forming apparatus comprising the optical writing apparatus according to any one of claims 1 to 10 .

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