JP2014162164A - Exposure device and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exposure device capable of performing optical writing of high quality.SOLUTION: A writing control part comprises: a pitch measurement part 401 which generates pitch data from an output signal of a TM sensor and an output signal of a home position sensor; an interval data generation part 402 which generates interval data for adjusting cycles of an LSYNC signal so that a pitch error is suppressed based upon the pitch data; an exposure timing signal generation part 403 which generates a LOAD signal, an STBa signal, an STBb signal, an STBc signal, an STBd signal, a CLK signal, and an LSYNC signal; an image data generation part 404 which outputs image data of one line, etc. In this case, unevenness in line pitch in a sub direction due to eccentricity characteristics of a photoreceptor drum is corrected to achieve precise multiple exposure at the same position with a last latent image during the multiple exposure.

Description

  The present invention relates to an exposure apparatus and an image forming apparatus, and more particularly to an exposure apparatus that exposes an image carrier and an image forming apparatus that includes the exposure apparatus.

  In recent years, with the development of information equipment, the demand for printers and copiers in small offices (small offices) and home offices has increased.

  A print head using a light source having a plurality of light emitting portions such as an LED array and an organic EL array and a lens array is used in an exposure apparatus of a laser printer or a copying machine. Although there is an exposure apparatus (optical scanning apparatus) using a semiconductor laser and a polygon scanner, it is more advantageous to use a print head from the viewpoint of downsizing the apparatus.

  For example, Patent Document 1 includes a plurality of light emitting elements arranged two-dimensionally by providing a plurality of lines arranged in the main scanning direction of the image carrier in the sub-scanning direction of the image carrier, and performs multiple exposure. An optical head is disclosed.

  Further, Patent Document 2 includes light emitting elements that are arranged in a zigzag two-dimensionally by providing a plurality of lines arranged in the main scanning direction of the image carrier in the sub-scanning direction of the image carrier. An optical head for performing exposure is disclosed.

  Further, in Patent Document 3, a change in drive speed with time during one rotation period of the drum-shaped image forming body is detected or measured and stored as driving unevenness, and the image exposure of the image exposure unit corresponds to the stored driving unevenness. A color image forming apparatus is disclosed in which the timing is controlled so as to operate.

  Further, Patent Document 4 has a line head in which a plurality of organic EL elements are arranged in a row in the main scanning direction, and an object is to improve the image quality by suppressing the influence of the eccentricity of the latent image carrier gear. An image forming apparatus is disclosed.

  The demand for image quality in image forming apparatuses is increasing year by year. However, in the image forming apparatus having the optical head disclosed in Patent Document 1 and Patent Document 2, and in the image forming apparatus disclosed in Patent Document 3 and Patent Document 4, the required level of image quality is obtained. It was difficult.

  The present invention is an exposure apparatus that exposes an image carrier, and includes a plurality of light emitting unit rows each having a plurality of light emitting units arranged in a first direction, and the plurality of light emitting unit rows are the first light emitting unit rows. And driving the plurality of light emitting section rows while relatively moving the image carrier in the second direction and the light sources arranged along a second direction orthogonal to the direction of the plurality of light emission A control device that multiple-exposes the exposure position exposed in one light-emitting portion row in the portion row in another light-emitting portion row in the plurality of light-emitting portion rows, and the control device includes the second in the image carrier. In accordance with the exposure position with respect to the direction, the interval data which is the time interval from lighting to the next lighting in the one light emitting unit row is obtained, and the plurality of light emitting unit rows are driven based on the interval data. Exposure apparatus.

  According to the exposure apparatus of the present invention, high-quality exposure can be performed.

1 is a diagram for describing a schematic configuration of a color printer according to an embodiment of the present invention. FIG. It is a figure for demonstrating the external appearance of a print head. In FIG. 2, it is a figure of the state which removed the shielding member. In FIG. 2, it is a figure of the state which removed the housing. In FIG. 2, it is a figure of the state which removed the housing and the shielding member. It is a figure for demonstrating a light emitting member. It is a block diagram for demonstrating a write-control part. It is a figure for demonstrating the pattern for pitch measurement. FIG. 6 is a diagram for explaining a toner image of a pitch measurement pattern on an intermediate transfer belt. It is a figure for demonstrating pitch data. It is a figure for demonstrating the relationship between a pitch error and the rotation angle of a photoconductor drum. It is a figure for demonstrating the relationship between an element row | line | column and the irradiation position on a photoconductor drum. It is a figure for demonstrating the phase difference of a pitch error. It is a figure for demonstrating a some line. It is a figure for demonstrating space | interval data. It is a block diagram for demonstrating an exposure timing signal generation part. It is a timing chart of each signal in a writing control part. It is a timing chart of each signal output from a writing control part. It is a block diagram for demonstrating a drive device. It is a timing chart of each signal in a drive device. It is a figure for demonstrating the modification of a light emitting member.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic configuration of a color printer 2000 according to an embodiment.

  The color printer 2000 is a tandem multicolor printer that forms a full-color image by superimposing four colors (black, cyan, magenta, and yellow), and includes four photosensitive drums (1K, 1C, 1M, 1Y), 4 chargers (2K, 2C, 2M, 2Y), 4 print heads (3K, 3C, 3M, 3Y), 4 developers (4K, 4C, 4M, 4Y), 4 Transfer rollers (5K, 5C, 5M, 5Y), four cleaning units (6K, 6C, 6M, 6Y), four home position sensors (7K, 7C, 7M, 7Y), intermediate transfer belt 201, transport Belt 202, secondary transfer roller 203, fixing device 204, paper feed tray 205, paper feed roller 206, communication control device 208, printer control device 209 for comprehensively controlling each of the above parts, TM Capacitors 211, and a printer housing 210 in which they are housed.

  The communication control device 208 controls bidirectional communication with a host device (for example, a personal computer) via a network or the like.

  The printer control device 209 includes a CPU, a ROM described in a program written in code readable by the CPU, various data used when executing the program, a RAM as a working memory, an analog signal, and the like. An A / D conversion circuit that converts the signal into a digital signal, an oscillation circuit that generates a reference clock signal, a write control unit for each print head, and the like.

  The photosensitive drum 1K, the charging device 2K, the print head 3K, the developing device 4K, the transfer roller 5K, the cleaning unit 6K, and the home position sensor 7K are used as a set and constitute an image forming unit that forms a black image.

  The photosensitive drum 1M, the charger 2M, the print head 3M, the developing device 4M, the transfer roller 5M, the cleaning unit 6M, and the home position sensor 7M are used as a set and constitute an image forming unit that forms a magenta image.

  The photosensitive drum 1C, the charging device 2C, the print head 3C, the developing device 4C, the transfer roller 5C, the cleaning unit 6C, and the home position sensor 7C constitute an image forming unit that forms a cyan image.

  The photosensitive drum 1Y, the charger 2Y, the print head 3Y, the developing device 4Y, the transfer roller 5Y, the cleaning unit 6Y, and the home position sensor 7Y are used as a set and constitute an image forming unit that forms a yellow image.

  Each photosensitive drum has a photosensitive layer formed on the surface thereof. The surface of each photosensitive drum is the exposed surface. Each photosensitive drum is rotated in the direction of the arrow in the plane of FIG. 1 by a rotation mechanism (not shown).

  Each charger uniformly charges the surface of the corresponding photosensitive drum.

  Each print head is controlled by the printer controller 209 to irradiate the surface of the corresponding charged photosensitive drum with light modulated based on the image information of the corresponding color. Thereby, a latent image corresponding to the image information is formed on the surface of each photosensitive drum. The latent image formed here moves in the direction of the corresponding developing device as the photosensitive drum rotates. Details of each print head will be described later.

  By the way, in each photoconductor drum, areas where image information is written are called “effective scanning area”, “image forming area”, “effective image area”, and the like.

  Further, the moving direction of the latent image on each photosensitive drum is referred to as “sub-direction”, and the direction orthogonal to the sub-direction on each photosensitive drum is referred to as “main direction”.

  Each developing device causes toner to adhere to the latent image formed on the surface of the corresponding photosensitive drum, and visualizes the latent image. Here, the toner-attached image (toner image) moves in the direction of the corresponding transfer roller as the photosensitive drum rotates.

  Each transfer roller transfers the toner image to the intermediate transfer belt 201. The yellow, magenta, cyan, and black toner images are superimposed on the intermediate transfer belt 201 to form a color image.

  Recording paper is stored in the paper feed tray 205. A paper feed roller 206 is disposed in the vicinity of the paper feed tray 205. The paper feed roller 206 takes out the recording paper one by one from the paper feed tray 205 and sends it out toward the transport belt 202 at a predetermined timing. .

  The recording paper on the conveyance belt 202 moves toward the intermediate transfer belt 201, and the color image on the intermediate transfer belt 201 is transferred by the secondary transfer roller 203. The recording paper on which the color image is transferred is sent to the fixing device 204.

  In the fixing device 204, heat and pressure are applied to the recording paper, whereby the toner is fixed on the recording paper. The recording paper on which the toner is fixed is sent to a paper discharge tray (not shown) via a paper discharge roller (not shown), and is sequentially stacked on the paper discharge tray.

  Each cleaning unit removes toner (residual toner) remaining on the surface of the corresponding photosensitive drum. The surface of the photosensitive drum from which the residual toner has been removed returns to the position facing the corresponding charger again.

  Each home position sensor detects the home position of rotation in the corresponding photosensitive drum. Each home position sensor generates a pulse each time the corresponding photosensitive drum rotates once. The output signal of each home position sensor is sent to the printer control device 209.

  The TM sensor 211 detects toner on the intermediate transfer belt 201. The output signal of the TM sensor 211 is sent to the printer control device 209.

  Further, the color printer 2000 moves each print head between a first position close to the surface of the corresponding photosensitive drum and a second position separated from the surface of the corresponding photosensitive drum. Four moving mechanisms (not shown) are provided. The first position is a position when a latent image is formed on the photosensitive drum. The second position is also called a retracted position and is a position for maintenance. Each moving mechanism can be composed of, for example, a spring member, a print head holding member that holds the corresponding print head, and a print head whole holding member that holds the spring member and the print head holding member. In this case, when the print head holding member is pressed in the direction close to the surface of the photosensitive drum by the spring member and the print head is to be retracted, the print head holding member is separated from the surface of the photosensitive drum. The print head can be retracted by pulling in the direction.

  Next, details of each print head will be described.

  The four print heads have the same configuration. Therefore, here, the print head 3K will be described in detail as a representative.

  As shown in FIG. 2 as an example, the print head 3K includes a light source 300, a rod lens array 304, a housing 306, two shielding members 310, and the like.

  Here, in the XYZ three-dimensional orthogonal coordinate system, the direction along the rotation axis of the photosensitive drum 1K is the Y-axis direction, and the direction in which the light (principal ray) from the print head 3K is directed to the photosensitive drum 1K is the Z-axis direction. . Therefore, the Y-axis direction is the main direction, and the X-axis direction is a direction corresponding to the sub direction.

  The light source 300 is accommodated in the housing 306.

  As shown in FIGS. 3 to 5, the light source 300 includes a substrate 301, a light emitting member 302, and a driving device 303. FIG. 3 is a view when the shielding member 310 is removed from FIG. FIG. 4 is a view when the housing 306 is removed from FIG. FIG. 5 is a view when the two shielding members 310 and the housing 306 in FIG. 2 are removed.

  The substrate 301 is a rectangular plate member whose longitudinal direction is the Y-axis direction. The light emitting member 302 and the driving device 303 are mounted on the + Z side surface of the substrate 301. Here, as the substrate 301, a printed circuit board using a so-called glass cloth epoxy as a base material is used.

  As shown in FIG. 6 as an example, the light emitting member 302 has a plurality of element rows each composed of a plurality of organic EL elements arranged along the Y-axis direction. Here, as an example, there are four element rows (element row a, element row b, element row c, and element row d). Note that the number of element rows is not limited to four. The element column b is disposed on the + X side of the element column a, the element column c is disposed on the + X side of the element column b, and the element column d is disposed on the + X side of the element column c. Each organic EL element emits light in the + Z direction.

  By the way, the lifetime of the organic EL element is shortened when the amount of emitted light is increased. On the other hand, if the amount of light emitted from the organic EL element is reduced in order to extend the life, the exposure amount necessary for forming a latent image cannot be obtained.

  Therefore, in this embodiment, a so-called multiple exposure method is employed in which pixels for one dot are formed by multiple exposure. That is, one line of image is exposed to the photosensitive drum with one element row, and then the photosensitive drum is rotated so that the line reaches the position facing the next element row. The image of one line is again exposed with the element row.

  The printer control device 209 has a write control unit for each print head. That is, it has four write control units. These four write control units have the same configuration. Therefore, here, as a representative, the write control unit of the print head 3K will be described in detail.

  As shown in FIG. 7 as an example, the writing control unit includes a pitch measurement unit 401, an interval data generation unit 402, an exposure timing signal generation unit 403, an image data generation unit 404, and the like.

  The pitch measurement unit 401 creates pitch data based on the output signal of the TM sensor 211 and the output signal of the home position sensor 7K. Here, a procedure for creating the pitch data will be described.

  First, the pitch measurement unit 401 instructs the print head 3K to form a pitch measurement pattern as shown in FIG. 8 as an example. This pitch measurement pattern is a pattern in which a plurality of line patterns having the main direction as the longitudinal direction are arranged at equal intervals p in the sub direction. As a result, a latent image of the pitch measurement pattern is formed on the photosensitive drum 1K. The latent image is developed by the developing device 4K to form a toner image. The toner image is transferred to the intermediate transfer belt 201 by the transfer roller 5K.

  Next, the pitch measurement unit 401 obtains the pitch of the line pattern in the toner image based on the output signal of the TM sensor 211.

  By the way, the photosensitive drum 1K is not a perfect circle. In some cases, the gear for rotating the photosensitive drum 1K is eccentric. Therefore, the pitch of the line pattern in the toner image is not constant as shown in FIG. 9 as an example. Hereinafter, the difference from p, which is a desired pitch, is referred to as “pitch error”.

  Next, the pitch measurement unit 401 obtains the relationship between the elapsed time from the rising timing of the output signal and the pitch error based on the output signal of the home position sensor 7K. This is pitch data (see FIG. 10). Note that the relationship between the elapsed time and the pitch error may be approximated by a curve, and the approximate curve may be used as pitch data.

  FIG. 11 shows an example of the relationship between the pitch error and the output signal of the home position sensor 7K. According to this, the pitch error changes at the same cycle as the rotation cycle of the photosensitive drum 1K.

  Further, as shown in FIG. 12, the exposure position of the light from the print head 3K on the photosensitive drum 1K differs for each element array, so that the approximate curve has a phase shift between the element arrays. (See FIG. 13).

  Therefore, in this embodiment, the pitch error and the phase shift are corrected by the writing control unit.

  An image (latent image) formed on the photosensitive drum 1K is written at a line pitch corresponding to the resolution in the sub direction. Here, it is assumed that the outer peripheral length of the photosensitive drum 1K is L, and writing is performed in n lines. Therefore, when the image (latent image) is formed with reference to the home position of the photosensitive drum 1K, the relationship between each line and the position on the photosensitive drum 1K can be known (see FIG. 14).

  Returning to FIG. 7, the interval data creation unit 402 refers to the pitch data from the pitch measurement unit 401, obtains an expected pitch error for each line, and immediately before the line so that the pitch error is suppressed. Elapsed time from the line exposed to is obtained as interval data (see FIG. 15). The line exposed immediately before the first line is the nth line.

  The creation of the interval data is performed when the apparatus is first started up and when the number of printed recording sheets reaches a predetermined number.

  As shown in FIG. 16 as an example, the exposure timing signal generation unit 403 includes an LSYNC signal generation unit 410, a CLK signal generation unit 420, a LOAD signal generation unit 421, an interval data load signal generation unit 411, a first holding unit 412, A second holding unit 413, a third holding unit 414, a fourth holding unit 415, an STBa signal generation unit 416, an STBb signal generation unit 417, an STBc signal generation unit 418, an STBd signal generation unit 419, and the like are included.

  The LSYNC signal generation unit 410 generates an LSYNC signal. The LSYNC signal is a line synchronization signal that sets the exposure start timing of one line, and generates a rectangular pulse at every fixed timing. That is, the cycle of the LSYNC signal is constant. The interval data creation unit 402 sequentially outputs interval data in synchronization with the LSYNC signal.

  The CLK signal generation unit 420 generates a CLK signal that is a clock signal of image data.

  The LOAD signal generation unit 421 generates a LOAD signal. This LOAD signal is a signal for generating a rectangular pulse at the timing when the output of image data for one line is completed. Specifically, a time from the rise timing of the LSYNC signal to the end of the output of the image data is set in advance, and a rectangular pulse is generated at the timing when the time has elapsed since the rise of the LSYNC signal.

  The interval data load signal generation unit 411 generates an interval data load signal in synchronization with the LSYNC signal. This interval data load signal is a signal for generating a rectangular pulse at a timing when a predetermined time has elapsed from the rising timing of the LSYNC signal.

  The first holding unit 412 transfers the held data to the second holding unit 413 in synchronization with the interval data load signal, and sets the interval data from the interval data creating unit 402 as new held data.

  The second holding unit 413 transfers the held data to the third holding unit 414 in synchronization with the interval data load signal, and uses the transfer data from the first holding unit 412 as new held data.

  The third holding unit 414 transfers the held data to the fourth holding unit 415 in synchronization with the interval data load signal, and sets the transfer data from the second holding unit 413 as new held data.

  The fourth holding unit 415 sets new transfer data to the transfer data from the third holding unit 414 in synchronization with the interval data load signal.

  As described above, the interval data is sequentially shifted from the first holding unit 412 to the fourth holding unit 415.

  The STBa signal generation unit 416 generates an STBa signal based on the LSYNC signal and the data held in the first holding unit 412.

  The STBb signal generation unit 417 generates an STBb signal based on the LSYNC signal and the data held in the second holding unit 413.

  The STBc signal generation unit 418 generates an STBc signal based on the LSYNC signal and the data held in the third holding unit 414.

  The STBd signal generation unit 419 generates an STBd signal based on the LSYNC signal and the data held in the fourth holding unit 415.

  The STBa signal, STBb signal, STBc signal, and STBd signal are strobe signals in which the cycle of the LSYNC signal is adjusted based on the interval data. That is, the interval data is data for adjusting the cycle of the LSYNC signal so that the pitch error is suppressed based on the pitch data. Hereinafter, the STBa signal, STBb signal, STBc signal, and STBd signal are collectively referred to as “STB signal”.

  FIG. 17 shows a timing chart of signals generated in each signal generation unit and data held in each holding unit. The STBa signal generation unit 416, the STBb signal generation unit 417, the STBc signal generation unit 418, and the STBd signal generation unit 419, for example, reset the output signal when detecting the rise of a start trigger signal (not shown) instructing the start of writing. Then, rectangular pulses are generated at the same timing.

  Returning to FIG. 7, the image data creation unit 404 creates image data by performing image processing on the image information. When the rising edge of the LSYNC signal is detected, the image data creation unit 404 outputs image data for one line to the print head 3K together with the CLK signal in synchronization with the CLK signal. Here, the image data of the first line is DL1, the image data of the second line is DL2, the image data of the third line is DL3,.

  An example of a timing chart of signals output from the writing control unit to the driving device 303 of the print head 3K is shown in FIG.

  As illustrated in FIG. 19 as an example, the driving device 303 includes a shift register 501 and four F / F groups (502a, 502b, 502c, and 502d).

  The shift register 501 has the same number of registers as the number of organic EL elements constituting one element row, and holds image data from the write control unit. Note that the data held in the shift register 501 is 0 before the image data is sent from the writing control unit.

  The F / F group 502a takes in the data held in the shift register 501 in synchronization with the LOAD signal and sets it as new data held. The F / F group 502b takes in the retained data of the F / F group 502a in synchronization with the LOAD signal and sets it as new retained data. The F / F group 502c takes in the retained data of the F / F group 502b in synchronization with the LOAD signal and sets it as new retained data. The F / F group 502d takes in the retained data of the F / F group 502c in synchronization with the LOAD signal and sets it as new retained data.

  The element array a is driven based on the data held in the F / F group 502a in synchronization with the STBa signal. The element row b is driven based on the data held in the F / F group 502b in synchronization with the STBb signal. The element array c is driven based on the data held in the F / F group 502c in synchronization with the STBc signal. The element array d is driven based on the data held in the F / F group 502d in synchronization with the STBd signal.

  An example of a timing chart of each signal in the driving device 303 is shown in FIG.

  When the STBa signal rises at time t1, the element row a is driven based on the image data DL1 of the F / F group 502a. At this time, since the data held in the F / F group 502b, the F / F group 502c, and the F / F group 502d is 0, the element row b, the element row c, and the element row d are not driven.

  Even if the STBd signal rises at time t2, since the data held in the F / F group 502d is 0, the element array d is not driven.

  Even if the STBc signal rises at time t3, since the data held in the F / F group 502c is 0, the element array c is not driven.

  When the STBb signal rises at time t4, the element row b is driven based on the image data DL1 held in the F / F group 502b. Here, the exposure is performed on the latent image formed by the element array a at time t1.

  When the STBa signal rises at time t5, the element array a is driven based on the image data DL2 held in the F / F group 502a.

  Even if the STBd signal rises at time t6, the data held in the F / F group 502d is 0, so the element row d is not driven.

  When the STBc signal rises at time t7, the element array c is driven based on the image data DL1 held in the F / F group 502c. Here, the latent image formed by the element array a at time t1 and superimposedly exposed by the element array b at time t4 is overlaid and exposed.

  When the STBb signal rises at time t8, the element row b is driven based on the image data DL2 held in the F / F group 502b. Here, the exposure is performed on the latent image formed by the element array a at time t5.

  When the STBa signal rises at time t9, the element array a is driven based on the image data DL3 held in the F / F group 502a.

  When the STBd signal rises at time t10, the element row d is driven based on the image data DL1 held in the F / F group 502d. Here, the exposure is performed by superimposing on the latent image formed by the element array a at time t1, multiple-exposed by the element array b at time t4, and further multiple-exposed by the element array c at time t7.

  When the STBc signal rises at time t11, the element array c is driven based on the image data DL2 held in the F / F group 502c. Here, the latent image formed by the element array a at time t5 and superimposedly exposed by the element array b at time t8 is superimposed and exposed.

  When the STBb signal rises at time t12, the element row b is driven based on the image data DL3 held in the F / F group 502b. Here, the exposure is performed on the latent image formed by the element array a at time t9.

  When the STBa signal rises at time t13, the element array a is driven based on the image data DL4 held in the F / F group 502a.

  As described above, in this embodiment, the latent image necessary for image formation is formed by quadruple exposure. Since the STB signal is generated by sequentially shifting the interval data to the next line, the multiple exposure can be performed with the same pitch as the exposure with the previous element row. Therefore, multiple exposure can be accurately performed at the same position as the previous latent image, and deterioration in image quality due to an exposure position shift can be suppressed. That is, a high-quality latent image can be formed on the photosensitive drum 1K. As a result, a high quality output image can be obtained.

  As is apparent from the above description, in the color printer 2000 according to the present embodiment, the exposure apparatus of the present invention is configured by the print heads and write control units for the respective colors. Moreover, the control apparatus of this invention is comprised by the write-control part.

  As described above, according to the color printer 2000 according to the present embodiment, the four image forming units, the intermediate transfer belt 201, the conveyance belt 202, the secondary transfer roller 203, the fixing device 204, the printer control device 209, and the TM sensor 211. Etc.

  Each image forming unit includes a photosensitive drum, a charger, a print head, a developing device, a transfer roller, a cleaning unit, and a home position sensor.

  The printer control device 209 has a write control unit for each print head. Each writing control unit includes a pitch measurement unit 401, an interval data generation unit 402, an exposure timing signal generation unit 403, an image data generation unit 404, and the like.

  The pitch measurement unit 401 obtains a pitch error based on the output signal of the TM sensor 211 when the pitch measurement pattern is detected, and obtains pitch data obtained by adding position information obtained from the output signal of the home position sensor to the pitch error. create.

  The interval data creation unit 402 creates interval data for adjusting the cycle of the LSYNC signal so that the pitch error is suppressed for each line based on the pitch data.

  The exposure timing signal generation unit 403 generates a LOAD signal, an STBa signal, an STBb signal, an STBc signal, an STBd signal, a CLK signal, and an LSYNC signal, and outputs them to the print head. The STBa signal, STBb signal, STBc signal, and STBd signal are strobe signals in which the cycle of the LSYNC signal is adjusted based on the interval data.

  The image data creation unit 404 performs image processing on the image information to create image data, and outputs image data for one line to the print head in synchronization with the LSYNC signal.

  In this case, the latent image composed of a plurality of lines formed on the photosensitive drum is formed at a uniform pitch by correcting the line pitch roughness in the sub-direction due to the eccentric characteristic of the photosensitive drum. Further, since each STB signal is generated by sequentially shifting the interval data to the next line, when performing multiple exposure, the exposure can be performed at the same pitch as that used for the previous element row, and the previous latent Multiple exposure can be performed at the same position as the image with high accuracy. That is, the exposure position shift is suppressed, and high-quality optical writing can be performed.

  As a result, the color printer 2000 can obtain a high-quality output image.

  In the above embodiment, as shown in FIG. 21 as an example, a plurality of organic EL elements may be arranged in a staggered manner.

  Moreover, in the said embodiment, at least one part of the light emission member 302 and the drive device 303 may be united, and may be formed into the IC chip.

  Moreover, although the said embodiment demonstrated the case where the light emitting member 302 had four element rows, it is not limited to this.

  Moreover, although the said embodiment demonstrated the case where each light emission part was an organic EL element, it is not limited to this.

  In the above embodiment, a color printer having four photosensitive drums has been described as the image forming apparatus. However, the present invention is not limited to this. For example, a printer having one photosensitive drum may be used. Further, a color printer using auxiliary colors may be used.

  In the above embodiment, the image forming apparatus in which the toner image is transferred from the photosensitive drum to the recording paper via the intermediate transfer belt has been described. However, the present invention is not limited to this, and the toner image is transferred from the photosensitive drum. An image forming apparatus that is directly transferred to a recording sheet may be used.

  DESCRIPTION OF SYMBOLS 201 ... Intermediate transfer belt 202 ... Conveyor belt 203 ... Secondary transfer roller 204 ... Fixing device 209 ... Printer control device 211 ... TM sensor 300 ... Light source 301 ... Substrate 302 ... Light emitting member 303 ... Drive Apparatus 304 304 rod lens array 306 housing 310 shield member 401 pitch measurement unit 402 interval data generation unit 403 exposure timing signal generation unit 404 image data generation unit 411 interval data load Signal generation unit, 412... First holding unit (one of a plurality of holding units), 413... Second holding unit (one of a plurality of holding units), 414... Third holding unit (one of a plurality of holding units) ) 415... Fourth holding unit (one of a plurality of holding units) 416... STBa signal generation unit 417... STBb signal generation unit 418... STBc signal generation unit 419. Bd signal generator, 501... Shift register, 502a, 502b, 502c, 502d... F / F group, 2000... Color printer (image forming apparatus), 1K, 1C, 1M, 1Y. 2K, 2C, 2M, 2Y ... charger, 3K, 3C, 3M, 3Y ... print head, 4K, 4C, 4M, 4Y ... developer, 5K, 5C, 5M, 5Y ... transfer roller, 6K, 6C, 6M, 6Y: Cleaning unit, 7K, 7C, 7M, 7Y: Home position sensor.

JP 2003-341140 A JP 2003-341141 A JP-A-9-81006 Japanese Patent No. 4752346

Claims (7)

An exposure apparatus that exposes an image carrier,
Each includes a plurality of light emitting unit rows each having a plurality of light emitting units arranged along the first direction, and the plurality of light emitting unit rows are arranged along a second direction orthogonal to the first direction. A light source;
The plurality of light emitting unit rows are driven while the image carrier is relatively moved in the second direction, and an exposure position exposed in one light emitting unit row in the plurality of light emitting unit rows is set to the plurality of light emitting units. A control device that performs multiple exposure in another light emitting unit row in the unit row,
The control device obtains interval data that is a time interval from lighting to the next lighting in the one light emitting unit row according to an exposure position in the second direction on the image carrier, and based on the interval data An exposure apparatus that drives the plurality of light emitting unit rows.   The control device has a plurality of holding units individually corresponding to the plurality of light emitting unit rows and temporarily holding the interval data, and after the one light emitting unit row is turned on, the one light emitting unit The interval data held in a holding unit corresponding to a column is transferred to a holding unit corresponding to a light emitting unit row that is next exposed at a position exposed by the one light emitting unit row. 2. The exposure apparatus according to 1. The image carrier is a cylindrical member that rotates about an axis parallel to the first direction,
The exposure apparatus according to claim 1, wherein the control device creates the interval data based on an eccentricity characteristic of the image carrier.   The decentering characteristic of the image carrier is the plurality of line patterns in the image when an image is formed on the image carrier according to image data including a plurality of line patterns having the same pitch in the second direction. The exposure apparatus according to claim 3, wherein the pitch error is the following.   The said control apparatus produces the said space | interval data so that the pitch of these line patterns in the said image may become equal to the pitch of these line patterns in the said image data. Exposure equipment.   The exposure apparatus according to claim 1, wherein the light emitting unit is an organic EL element. An image carrier;
An image forming apparatus comprising the exposure apparatus according to claim 1, wherein the image carrier is exposed according to image information.

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