Exposure apparatus and image forming apparatus

Abstract

To more correctly correct a mounting deviation of a plurality of chips mounted on a substrate.SOLUTION: An exposure device comprises: a substrate on which a first chip and a second chip having light emitting elements are sequentially mounted in a rotation axial direction of a photoreceptor; a controller which transmits a signal for controlling the substrate; a first data signal line which is connected to the first chip and transmits a data signal to the first chip; a second data signal line which is connected to the second chip and transmits the data signal to the second chip; a first selection signal line which is connected to the first chip and transmits a selection signal indicating that the data signal is for the first chip; a second selection signal line which is connected to the second chip and transmits a selection signal indicating that the data signal is for the second chip; and a storage unit which stores a deviation amount from a reference position of the chip mounted on the substrate. The controller calculates for each chip a correction amount for exposure of each chip at the reference position on the basis of the deviation amount stored in the storage unit, and adjusts the output timing for outputting the signal to each chip with the calculated correction amount.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to an exposure apparatus for exposing a photoreceptor and an image forming apparatus including the same.

Background Art

[0002] In an electrophotographic image forming apparatus such as a printer, a method of exposing a photosensitive drum using an exposure apparatus using an LED, an organic EL, or the like to form a latent image is generally known. The exposure apparatus includes a light emitting element array arranged in the rotation axis direction (longitudinal direction) of the photosensitive drum and a rod lens array that forms an image of the light of the light emitting element array on the photosensitive drum. The LED and the organic EL are known to have a surface light emitting shape in which the irradiation direction of light from the light emitting surface is the same as that of the rod lens array. Further, the light emitting element array is known to have a configuration in which a plurality of light emitting element array chips each having a plurality of light emitting elements are mounted on a substrate.

[0003] Here, the length in the longitudinal direction of the light emitting element array is determined according to the width of the image area on the photosensitive drum, and the interval between the light emitting elements is determined according to the resolution of the printer. For example, in the case of a printer with a resolution of 1200 dpi, since the interval between pixels is 21.16 μm (omitting three digits after the decimal point), the interval between the light emitting elements is also 21.16 μm. In a printer using such an exposure apparatus, since the number of parts used is smaller than that of a laser scanning type printer in which a laser beam is deflected and scanned by a polygon motor, it is easy to reduce the size and cost of the apparatus.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when mounting the light-emitting element array chip on the substrate, mounting misalignment may occur in the rotational axis direction of the photosensitive drum or in the rotational direction orthogonal to the rotational axis direction of the photosensitive drum due to mechanical accuracy of the mounting apparatus for mounting the light-emitting element array chip on the substrate or misalignment during adhesion.

[0006] Patent Document 1 describes a recording apparatus in which a head unit having a plurality of recording heads arranged in a direction (main scanning direction) orthogonal to the conveyance direction (sub-scanning direction) of a recording medium is arranged in parallel in the sub-scanning direction by the number of recording colors. Further, it is described that the image quality of an image recorded on the recording medium is controlled by changing the position of a predetermined recording pattern recorded on the recording medium by each recording head within each head unit. However, Patent Document 1 does not describe a specific configuration for solving the problem of mounting misalignment of a plurality of recording heads in the sub-scanning direction.

[0007] For example, among the aforementioned mounting misalignments, if it is a correction of the misalignment amount per pixel in the rotational direction, that is, the misalignment amount per line in the rotational direction, the correction is possible by shifting the output image line in the rotational direction by one line unit by image processing.

[0008] However, when the mounting misalignment of the light-emitting element array chip with respect to the substrate occurs in units less than one line (less than one pixel) in the rotational direction, it is difficult to accurately correct with only the aforementioned correction per line unit. In particular, with the recent trend towards high image quality, color misalignment and misalignment during reproduction of fine lines have been regarded as problems, and a more accurate response to the mounting misalignment of the light-emitting element array chip has been required.

[0009] An object of the present invention is to more accurately correct the mounting misalignment of a plurality of light-emitting element array chips mounted on a substrate and to enable a higher image quality output.

Means for Solving the Problem

[0010] A typical configuration of the present invention includes a substrate on which a first chip having a light-emitting element for exposing a photoreceptor and a second chip having the light-emitting element are mounted in order in the direction of the rotation axis of the photoreceptor, a controller for transmitting a signal for controlling the substrate, the signal including a data signal obtained by dividing image data for one line in the direction of the rotation axis of the photoreceptor for each chip, a common data signal line provided on the substrate, connected to the first chip and the second chip from the controller, and transmitting the divided data signal to the first chip and the second chip, a first selection signal line provided on the substrate, connected to the first chip from the controller, and transmitting a selection signal indicating that the divided data signal is for the first chip, a second selection signal line provided on the substrate independently of the first selection signal line, connected to the second chip from the controller, and transmitting a selection signal indicating that the divided data signal is for the second chip, and a storage unit for storing a deviation amount when the chip mounted on the substrate is displaced in the rotational direction orthogonal to the direction of the rotation axis of the photoreceptor from a reference position. The controller calculates, for each chip, a correction amount for each chip to expose at the reference position based on the deviation amount stored in the storage unit, adjusts an output timing for outputting the selection signal and the data signal to each chip with the calculated correction amount, transmits the selection signal and the data signal to the first chip through the first selection signal line and the common data signal line at the adjusted output timing, and then transmits the selection signal and the data signal to the second chip through the second selection signal line and the common data signal line at the adjusted output timing.

Advantages of the Invention

[0011] According to the present invention, the mounting deviation of a plurality of chips mounted on a substrate can be corrected more accurately, and a higher image quality output can be realized.

Brief Description of the Drawings

[0012]

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Modes for Carrying Out the Invention

[0013] Hereinafter, with reference to the drawings, preferred embodiments of the present invention will be exemplarily described in detail. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the following embodiments should be appropriately changed according to the configuration of the apparatus to which the present invention is applied and various conditions, and are not intended to limit the scope of the present invention only thereto.

[0014] [Example 1] (Configuration of the entire image forming apparatus) Using FIG. 1, the electrophotographic image forming apparatus in this embodiment will be briefly described. FIG. 1 shows the configuration of the entire image forming apparatus. This image forming apparatus is composed of a scanner unit 100, an image forming unit 103, a fixing unit 104, a paper feeding / conveying unit 105, and a printer control unit (not shown) that controls these components.

[0015] The scanner unit 100 irradiates illumination on the document placed on the document table, optically reads the document image, and converts the image into an electrical signal to create image data. In the image forming unit 103, the photosensitive drum 102 as an image carrier (photoconductor) is rotationally driven, and the photosensitive drum 102 is charged by the charger 107. The exposure head 106 as an exposure device emits light according to the image data, and the light emitted from the chip surface of the arranged light emitting element group is condensed onto the photosensitive drum 102 by the rod lens array to form an electrostatic latent image on the photosensitive drum 102. The developing device 108 develops the toner with respect to the electrostatic latent image formed on the photosensitive drum 102. The developed toner image is transferred onto the paper conveyed on the transfer belt 111. The image forming unit 103 has four image forming units that perform the above-described series of electrophotographic processes (charging, exposure, development, transfer), and arranges them in the order of cyan (C), magenta (M), yellow (Y), and black (K) to form a full-color image. The four image forming units sequentially execute the image forming operations of the magenta, yellow, and black image forming units after a predetermined time has elapsed since the start of image formation of the cyan image forming unit.

[0016] In the paper feeding / conveying unit 105, paper as a recording medium is fed from a pre-designated paper feeding unit among the internal paper feeding units 109a and 109b, the external paper feeding unit 109c, and the manual paper feeding unit 109d within the main body, and the fed paper is conveyed to the registration roller 110. The registration roller 110 conveys the paper onto the transfer belt 111 at the timing when the toner image formed in the image forming unit 103 described above is transferred onto the paper. An optical sensor 113 is disposed at the opposing position of the transfer belt 111 to detect the position of the test chart printed on the transfer belt 111 in order to derive the color misregistration amount between the respective image forming units. The color misregistration amount derived here is notified to the image controller unit 600 (see FIG. 6), and the image positions of each color are corrected. By this control, a full-color toner image without color misregistration is transferred onto the paper. The fixing unit 104 is constituted by a combination of rollers, incorporates a heat source such as a halogen heater, and melts and fixes the toner on the paper onto which the toner image has been transferred from the transfer belt 111 by heat and pressure. The paper on which the image has been fixed is discharged outside the image forming apparatus by the discharge roller 112.

[0017] The printer control unit (not shown) communicates with the control unit that controls the entire image forming apparatus, executes control according to its instructions, and while managing the states of the aforementioned scanner, image forming, fixing, and paper feeding / conveying units, gives instructions so that the whole can operate smoothly while maintaining harmony.

[0018] (Configuration of the exposure head) With reference to FIG. 2, the exposure head 106 as an exposure device for exposing the photosensitive drum 102 will be described. FIGS. 2(a) and 2(b) show the state of the arrangement of the exposure head 106 with respect to the photosensitive drum 102 and the state in which the light emitted from the light emitting element group 201 is condensed onto the photosensitive drum 102 by the rod lens array 203.

[0019] The exposure head 106 and the photosensitive drum 102 are each attached to the image forming apparatus by attachment members (not shown). The exposure head 106 includes a light emitting element group 201, a printed circuit board 202 on which the light emitting element group 201 is mounted, a rod lens array 203, and a housing 204 that attaches the rod lens array 203 and the printed circuit board 202. The light emitting element group 201 is composed of a plurality of light emitting element array chips each having a light emitting element. In the factory, the exposure head 106 is assembled and adjusted as a single unit, and focusing adjustment and light amount adjustment are performed to adjust the spot at the focusing position to a predetermined size. Here, the distance between the photosensitive drum 102 and the rod lens array 203 and the distance between the rod lens array 203 and the light emitting element group 201 are arranged to be a predetermined interval, so that the emitted light (light beam) from the light emitting element group 201 is imaged on the photosensitive drum 102. Therefore, during focusing adjustment, the attachment position of the rod lens array 203 is adjusted so that the distance between the rod lens array 203 and the light emitting element group 201 becomes a desired value. Also, during light amount adjustment, each light emitting element is sequentially caused to emit light individually, and the drive current of each light emitting element is adjusted so that the light condensed through the rod lens array 203 becomes a predetermined light amount.

[0020] (Configuration of Printed Circuit Board) FIG. 3 shows a printed circuit board 202 on which the light emitting element group 201 is arranged. FIG. 3(a) shows the surface of the printed circuit board 202 opposite to the surface on which the light emitting element group 201 is mounted (hereinafter referred to as the non-mounting surface). FIG. 3(b) shows the surface of the printed circuit board 202 on which the light emitting element group 201 is mounted (hereinafter referred to as the mounting surface).

[0021] The printed circuit board 202 is a board on which components can be mounted on both the non-mounted surface shown in Fig. 3(a) and the mounted surface shown in Fig. 3(b). As shown in Fig. 3(a), on the non-mounted surface of the printed circuit board 202, a connector 305 as a connection part for connecting to an image controller unit 600 (see Fig. 6) provided on a device side different from the printed circuit board 202 is mounted. A line for transmitting a signal for controlling the printed circuit board 202 from the image controller unit 600 and a power supply line are connected via the connector 305. Each light-emitting element mounted on the printed circuit board 202 is driven by receiving a signal from the image controller unit 600 via the connector 305.

[0022] As shown in Fig. 3(b), a light-emitting element group 201 composed of a plurality of light-emitting elements is mounted on the mounted surface of the printed circuit board 202. On the mounted surface of the printed circuit board 202, a plurality of light-emitting element array chips composed of a plurality of light-emitting elements are mounted in the rotational axis direction of the photosensitive drum 102 (the longitudinal direction of the printed circuit board 202). Here, the light-emitting element group 201 has a configuration in which 20 light-emitting element array chips 300-1 to 300-20 are arranged in a staggered manner in the longitudinal direction of the printed circuit board 202. In each of the light-emitting element array chips 300-1 to 300-20, 748 light-emitting elements as a plurality of light-emitting elements are arranged at a predetermined resolution pitch in the longitudinal direction of the chip. In this example, the pitch of the light-emitting elements adjacent in the longitudinal direction of the chip is a pitch of a resolution of 1200 dpi (about 21.16 μm), and the distance from end to end of the 748 light-emitting elements in the longitudinal direction within the chip is about 15.8 mm. The light-emitting element group 201 has 20 light-emitting element array chips 300-1 to 300-20 arranged in the longitudinal direction. As a result, the number of light-emitting elements that can be exposed in the longitudinal direction (rotational axis direction) of the photosensitive drum 102 in the light-emitting element group 201 is 14,960 elements, and image formation corresponding to an image width of about 316 mm in the longitudinal direction becomes possible. The light-emitting element array chips 300-1 to 300-20 are arranged in two rows in a staggered manner, and each row is arranged along the longitudinal direction of the printed circuit board 202. Also, a head information storage unit 610 is mounted on the printed circuit board 202.

[0023] Here, each light-emitting element array chip 300-1 to 300-20 is mounted on the printed circuit board 202 at a preset reference position. In FIG. 3(c), the position in contact with the reference line SL along the reference line SL which is a straight line in the longitudinal direction of the printed circuit board 202 (the rotation axis direction of the photosensitive drum) is set as the reference position of each light-emitting element array chip 300-1 to 300-20. In this example, each light-emitting element array chip 300-1 to 300-20 is arranged in a staggered pattern. Therefore, the odd-numbered light-emitting element array chips 300-1, 300-3, … 300-19 have the position in contact with one side in the direction orthogonal to the reference line SL (the downstream side in the rotation direction of the photosensitive drum) along the reference line SL as the reference position. The even-numbered light-emitting element array chips 300-2, 300-4, … 300-40 have the position in contact with the other side in the direction orthogonal to the reference line SL (the upstream side in the rotation direction of the photosensitive drum) along the reference line SL as the reference position. Here, the position in contact with the reference line SL along the reference line SL is set as the reference position, but it is not limited to this. For example, the reference position may be the mounting position of one light-emitting element array chip among the plurality of light-emitting element array chips mounted on the printed circuit board 202.

[0024] Also, in FIG. 3(c), the configuration in which each light-emitting element array chip 300-1 to 300-20 is arranged at a position in contact with the reference line SL is illustrated. In addition, a space of a predetermined number of lines is provided in the direction orthogonal to the reference line (the rotation direction of the photosensitive drum) between the odd-numbered light-emitting element array chips 300-1, 300-3, … 300-19 and the even-numbered light-emitting element array chips 300-2, 300-4, … 300-40. This will be described later. In this example, the predetermined number of lines is set to 4 lines.

[0025] The head information storage unit 610 is a storage unit that stores head information such as the light emission amount and mounting position of each light emitting element array chip 300, and is composed of a non-volatile memory or the like. The head information storage unit 610 stores, as head information, the amount of deviation when each light emitting element array chip 300 mounted on the printed circuit board 202 is deviated in the rotational direction orthogonal to the rotational axis direction of the photosensitive drum 102 from the reference position. As will be described later, the image controller unit 600 calculates, for each chip, a correction amount for each chip to expose at the reference position based on the amount of deviation stored in the head information storage unit 610. This amount of deviation is stored in the head information storage unit 610 when the printed circuit board 202 is manufactured.

[0026] Fig. 3(c) shows the state of the boundary portion between the chips of the light emitting element array chip 300. Here, the boundary portion between the chips of the light emitting element array chips 300-1 and 300-2 is exemplified. Also at the boundary portion between the chips, the pitch in the longitudinal direction of the light emitting element 301 is the pitch (about 21.16 μm) at a resolution of 1200 dpi. Further, the interval (S in the figure) in the drum rotation direction of the light emission points of the two rows of chips is arranged to be about 84.64 μm (4 pixels at 1200 dpi). Here, the interval S in the figure is the interval in the drum rotation direction between the center (light emission point) of the light emitting element 301 of one light emitting element array chip 300-1 and the center (light emission point) of the light emitting element 301 of the other light emitting element array chip 300-2. Also, each row is arranged along the longitudinal direction (drum rotation axis direction) of the printed circuit board 202, and the interval (L in the figure) in the drum rotation axis direction of the light emission points of the two rows is arranged to be about 21.16 μm (1 pixel at 1200 dpi). Here, the interval L in the figure is the interval between the center (light emission point) of the adjacent light emitting element 301 and the center (light emission point) of the light emitting element 301 in the drum rotation axis direction. Note that the intervals S and L between the light emitting elements are not limited to the above-described values and should be set as appropriate.

[0027] Here, in the longitudinal direction of the printed circuit board 202, a configuration in which 20 light-emitting element array chips 300-1 to 300-20 constituting one line are arranged in two rows in a staggered pattern is illustrated, but it is not limited thereto. For example, in the longitudinal direction of the printed circuit board, a configuration in which a plurality of light-emitting element array chips constituting one line are arranged in a single row may also be used.

[0028] (Configuration of the light-emitting element array chip) FIG. 4 shows a schematic of the planar configuration of the light-emitting element array chip 300. In the figure, the direction of arrow X is the longitudinal direction (rotation axis direction) of the photosensitive drum 102, and the direction of arrow Y is the rotation direction orthogonal to the rotation axis direction of the photosensitive drum 102.

[0029] The light-emitting element array chip 300 has a light-emitting portion 404 including a plurality of light-emitting elements and wire bonding pads (WB pads) 408 formed on a light-emitting substrate 402. Note that a circuit portion 406 (the portion surrounded by the dotted line in FIG. 4) for controlling the light-emitting portion 404 is built in the light-emitting substrate 402. The circuit portion 406 has a configuration including both an analog drive circuit (analog portion 706 shown in FIG. 7) and a digital control circuit (digital portion 700 shown in FIG. 7). Input / output of power supply to the circuit portion 406 and signals from outside the light-emitting element array chip 300 are performed through the wire bonding pads 408.

[0030] (Configuration of the light-emitting portion) The light-emitting portion 404 will be described with reference to FIG. 5. FIG. 5 is a schematic diagram of a part of the A-A' cross section of the light-emitting element array chip shown in FIG. 4 (one light-emitting element and its surroundings). In the figure, the direction of arrow Z is a direction orthogonal to the direction of arrow X and the direction of arrow Y in FIG. 4, and is the direction in which light is emitted from the light-emitting portion.

[0031] The light-emitting unit 404 has a configuration in which a plurality of lower electrodes 504, a light-emitting layer 506, and an upper electrode 508 are formed on a light-emitting substrate 402. The lower electrode 504 is an independent electrode, and the upper electrode 508 is a common electrode. The lower electrode 504 is formed with a width W in the arrow X direction. Also, a plurality of lower electrodes 504 are formed with a predetermined interval d therebetween and the adjacent lower electrodes 504 in the arrow X direction. The light-emitting layer 506 is formed between the lower electrode 504 and the upper electrode 508. Note that the light-emitting layer 506 may be formed continuously or may be divided into substantially the same size as the lower electrode 504. One light-emitting element 301 is formed by one independent lower electrode 504 and the portion surrounded by the light-emitting layer 506 and the upper electrode 508. A desired lower electrode among the plurality of lower electrodes 504 is selected, and the light-emitting layer 506 is energized through the selected lower electrode 504 and the upper electrode 508. By this energization, the light-emitting layer 506 at the location corresponding to the selected lower electrode 504 emits light and is emitted as emitted light 510 through the upper electrode 508. As the lower electrode 504, a metal having a high reflectance with respect to the emission wavelength of the light-emitting layer 506 is preferable, and Ag is used in this embodiment. As the lower electrode 504, Al or an alloy thereof, etc. can also be used as the metal having a high reflectance. Also, as the upper electrode 508, it is preferable that it is transparent with respect to the emission wavelength of the light-emitting layer 506, and indium tin oxide (ITO) is used in this embodiment. In this embodiment, an organic EL film is used as the light-emitting layer 506, but an inorganic EL layer or the like may be used instead of the organic EL layer.

[0032] (Control block) FIG. 6 shows a block diagram of the image controller unit 600 and the printed circuit board 202. In this embodiment, for simplicity of explanation, monochromatic processing will be described, but the same processing is assumed to be performed in parallel for four colors simultaneously.

[0033] The image controller unit 600 is provided on the device side (here, the image forming apparatus) different from the printed circuit board 202. The image controller unit 600 is a controller that transmits a signal for controlling the printed circuit board 202 to the printed circuit board 202. The signal includes a chip select signal representing the valid range of the image data, a clock signal, image data, a signal representing the delimiter for each line of the image data (hereinafter referred to as a line synchronization signal), and a communication signal with the CPU 603. The signal includes, as image data, a data signal obtained by dividing the image data for one line in the rotational axis direction of the photosensitive drum for each chip.

[0034] The chip select signal lines 6301 to 6320 are respectively connected from the image controller unit 600 to each light emitting element array chip 300-1 to 300-20 mounted on the printed circuit board 202. Specifically, the chip select signal line 6301 as the first selection signal line is connected from the image controller unit 600 to the light emitting element array chip 300-1 as the first chip. The chip select signal line 6302 as the second selection signal line is connected from the image controller unit 600 to the light emitting element array chip 300-2 as the second chip. Similarly, the other chip select signal lines 6303 to 6320 are also provided independently, and are respectively connected from the image controller unit 600 to the corresponding light emitting element array chips 300-3 to 300-20. Also, the chip select signal lines 6301 to 6320 (cs_01 to cs_20) transmit the 20 selection signals transmitted from the image controller unit 600 to each chip. Specifically, the chip select signal line 6301 (cs_01) as the first selection signal line transmits a selection signal indicating that the data signal transmitted from the image controller unit 600 to the light emitting element array chip 300-1 is for that chip. The chip select signal line 6302 (cs_02) as the second selection signal line transmits a selection signal indicating that the data signal transmitted from the image controller unit 600 to the light emitting element array chip 300-2 is for that chip. Similarly, the other chip select signal lines 6303 to 6320 (cs_03 to cs_20) also transmit a selection signal indicating that the data signal transmitted from the image controller unit 600 is for that chip to the chips 300-3 to 300-20.

[0035] The clock signal line 620 is connected to each light emitting element array chip 300-1 to 300-20 by branching one clock signal line 620. That is, the clock signal line 620 (clk) supplies the clock signal to each light emitting element array chip 300-1 to 300-20 by branching one clock signal line 620.

[0036] The image data signal lines 6401 to 6420 are respectively connected from the image controller unit 600 to the light emitting element array chips 300-1 to 300-20 mounted on the printed circuit board 202. Specifically, the image data signal line 6401 as the first data signal line is connected from the image controller unit 600 to the light emitting element array chip 300-1 as the first chip. The image data signal line 6402 as the second data signal line is connected from the image controller unit 600 to the light emitting element array chip 300-2 as the second chip. Similarly, the other image data signal lines 6403 to 6420 are also provided independently, and are connected from the image controller unit 600 to the corresponding light emitting element array chips 300-3 to 300-20 respectively. Also, the image data signal lines 6401 to 6420 (data_01 to data_20) transmit the data signals transmitted from the image controller unit 600 to each chip. Specifically, the image data signal line 6401 (data_01) as the first data signal line transmits the data signal transmitted from the image controller unit 600 to the light emitting element array chip 300-1 as the first chip. The image data signal line 6402 (data_02) as the second data signal line transmits the data signal transmitted from the image controller unit 600 to the light emitting element array chip 300-2 as the second chip. Similarly, the other image data signal lines 6403 to 6420 (data_03 to data_20) also transmit the data signals transmitted from the image controller unit 600 to the light emitting element array chips 300-3 to 300-20. In this embodiment, each data signal is 3 bits and realizes 8 gradation densities, and there are 20 systems of signals from data_01 (6401) to data_20 (6420), for a total of 60 signals.

[0037] The line synchronization signal line 650 is connected to the light emitting element array chips 300-1 to 300-20 by branching one line synchronization signal line 650. That is, the line synchronization signal line 650 (lsync_x) supplies the line synchronization signals to the light emitting element array chips 300-1 to 300-20 by branching one line synchronization signal line 650.

[0038] The communication signal line 660 (cpu_bus) supplies signals such as address signals and data signals for communication with the CPU 603 to each light-emitting element array chip 300-1 to 300-20, although the detailed configuration here will be omitted. The image controller unit 600 performs operations such as setting the operations for each light-emitting element array chip, writing and reading data to the head information storage unit 610 through the communication signal line 660.

[0039] As described above, the image controller unit 600 is a controller that transmits signals for controlling the printed circuit board 202 to the printed circuit board 202. The image controller unit 600 includes an image data generation unit 601, a chip data conversion unit 602 having a register unit 605, a CPU 603, and a synchronization signal generation unit 604. In the image controller unit 600, processing for image data and processing for printing timing are performed.

[0040] The image data generation unit 601 performs dithering processing on the image data received from the scanner unit 100 or outside the image forming apparatus at the resolution instructed by the CPU 603, and generates image data for print output. In this embodiment, it is assumed that dithering processing is performed at a resolution of 1200 dpi. Also, as described above, the image data represents 8 gradations with a density value of 0 to 7 in a 3-bit width, and 7 represents the maximum density.

[0041] The synchronization signal generation unit 604 generates a line synchronization signal. The CPU 603 designates the time interval of the signal period to the synchronization signal generation unit 604 with the period in which the surface of the photosensitive drum 102 moves in the rotation direction at a pixel size of 1200 dpi (about 21.16 μm) as one line period with respect to the previously determined rotation speed of the photosensitive drum 102. For example, when printing at a speed of 200 mm / s in the sheet conveyance direction, the time interval is designated with one line period as 105.8 μs (omitting two decimal places). Regarding the speed in the sheet conveyance direction, the CPU 603 calculates it using the set value (fixed value) of the printing speed set in the speed control means (not shown) of the photosensitive drum.

[0042] The chip data conversion unit 602 divides the image data for one line for each light emitting element array chip in synchronization with the line synchronization signal generated by the synchronization signal generation unit 604, and sends the divided data signals together with the clock signal and the chip select signal to the printed circuit board 202. The chip data conversion unit 602 performs predetermined control based on the information set in the register unit 605 by the CPU 603.

[0043] At this time, as shown in FIG. 3(b), the chip data conversion unit 602 corrects the image data so that the image data is exposed to the photosensitive drum 102 in one line with respect to the light emitting element array chips 300-1 to 300-20 arranged in a staggered pattern. The correction of the image data for each light emitting element array chip by the chip data conversion unit 602 will be described with reference to FIG. 18.

[0044] FIG. 18 is a diagram showing the correction of the image data. As described above, the light emitting element array chips 300-1 to 300-20 are arranged in a staggered pattern with respect to the printed circuit board 202. In addition, the light emitting element array chips 300-1 to 300-20 are actually arranged with a predetermined number of lines (4 pixels in this example) vacant between the odd-numbered light emitting element array chips and the even-numbered light emitting element array chips in the drum rotation direction.

[0045] Therefore, considering the number of lines between the chips as described above, the chip data conversion unit 602 adds the blank data (data with a density value of 0) of the predetermined number of lines to the light-emitting element array chip and outputs the result. For the odd-numbered light-emitting element array chips 300-1, 300-3, … 300-19, the chip data conversion unit 602 adds the blank data (data with a density value of 0) of the predetermined number of lines to the last line of the image data and outputs the result. Similarly, for the even-numbered light-emitting element array chips 300-2, 300-4, … 300-20, the chip data conversion unit 602 adds the blank data (data with a density value of 0) of the predetermined number of lines to the first line of the image data and outputs the result. As a result, even for the light-emitting element array chips arranged in a staggered pattern, by exposing the data signal output from the chip data conversion unit 602 with each light-emitting element array chip, it becomes possible to perform exposure and print output in a state where the lines of the original image data are aligned.

[0046] Here, blank data corresponding to the number of lines (4 pixels) equivalent to the interval between the light-emitting element array chips is added, but it is not limited to this. Considering the case where data remains in the memory without being cleared when the memory storing the image data is reset, the above-mentioned blank data may be used so that the remaining data is not output. Therefore, the predetermined number of lines to be added to the image data is not limited to the number corresponding to the interval between the above-mentioned light-emitting element array chips, and should be set appropriately.

[0047] As will be described later, the chip data conversion unit 602 controls the output timing of outputting the divided data signal as the above-mentioned image data, the chip select signal, etc. to the printed circuit board 202 based on information such as the correction amount set in the register unit 605 by the CPU 603.

[0048] The printed circuit board 202 is provided in the exposure head 106 as an exposure device. A plurality of light-emitting element array chips 300-1 to 300-20 having light-emitting elements are mounted on the printed circuit board 202.

[0049] The printed circuit board 202 is also provided with a head information storage unit 610 that stores head information. The head information storage unit 610 stores, in advance, as head information, the amount of deviation when each light-emitting element array chip 300 mounted on the printed circuit board 202 is deviated in the rotational direction orthogonal to the rotational axis direction of the photosensitive drum 102 from the reference position. The head information storage unit 610 is connected to the CPU 603 via the communication signal line 660.

[0050] The clock signal line 620, the line synchronization signal line 650, and the communication signal line 660 from the image controller unit 600 are respectively connected to each light-emitting element array chip 300 by branching. The clock signal line 620, the line synchronization signal line 650, and the communication signal line 660 connected to each light-emitting element array chip 300 are provided on the printed circuit board 202.

[0051] Also, the chip select signal lines 6301 to 6320 and the image data signal lines 6401 to 6420 from the image controller unit 600 are provided independently and are connected to the light-emitting element array chips 300-1 to 300-20 respectively. The chip select signal lines 6301 to 6320 and the image data signal lines 6401 to 6420 respectively connected to each light-emitting element array chip 300 are provided on the printed circuit board 202. That is, on the printed circuit board 202, the chip select signal lines 6301 to 6320 connected to the light-emitting element array chips 300-1 to 300-20 are respectively provided independently on the printed circuit board 202. Also, on the printed circuit board 202, the image data signal lines 6401 to 6420 connected to the light-emitting element array chips 300-1 to 300-20 are respectively provided independently on the printed circuit board 202.

[0052] (Digital circuit block inside the chip) Fig. 7 shows a block diagram of the circuit unit 406 in the light-emitting element array chip 300.

[0053] In this embodiment, each light-emitting element array chip 300 is connected to one 1-bit chip select signal line (any one of 6301 to 6320), one 1-bit clock signal line 620, one set of 3-bit image data signal lines (any one set of 6401 to 6420), one 1-bit line synchronization signal line 650, and a communication signal line 660 consisting of multiple bits, and signals are input. The circuit section 406 in the light-emitting element array chip 300 consists of a digital section 700 and an analog section 706.

[0054] The digital section 700 synchronizes with the clock input via the clock signal line 620, and based on the set value preset via the communication signal line 660, generates a pulse signal for causing the light-emitting element to emit light based on the chip select signal, image data signal, and line synchronization signal, and has the function of sending it to the analog section 706. The communication IF section 701 serves as an interface that controls the write and read of the set value to the register section 702 based on the communication signal from the CPU 603. The register section 702 stores the set values required for operation. These set values include the width information of the pulse signal generated by the pulse signal generation section 705, the period information of the line synchronization signal, and the set information of the drive current set by the analog section 706. The image data storage section 704 holds the image data while the input chip select signal is valid, and outputs the image data to the lighting control section 707 in synchronization with the line synchronization signal. The pulse signal generation section 705 generates a pulse signal required for lighting the light-emitting elements in the corresponding light-emitting element row based on the width information of the pulse signal and the line synchronization signal period set by the register section 702, and outputs it to the lighting control section 707. The lighting control section 707 controls whether to output the pulse signal from the pulse signal generation section 705 to the analog section 706 for each light-emitting element based on the image data from the image data storage section 704. The analog section 706 generates a signal required for driving the light-emitting element based on the pulse signal generated by the digital section 700.

[0055] FIG. 8 is a timing chart of signals output through the line synchronization signal line 650 (signal name: lsync_x), chip select signal lines 6301 to 6304 (signal names: cs_01 to cs_04), and image data signal lines 6401 to 6404 from the chip data conversion unit 602. In the description here, among the 20 light-emitting element array chips mounted on the substrate, signals for four light-emitting element array chips 300-1, 300-2, 300-3, and 300-4 are shown, but the same operation is performed for other light-emitting element array chips.

[0056] The line synchronization signal line 650 (signal name: lsync_x) is configured to transmit a signal indicating the data start position of each line as described above, and pulses that are enabled at regular intervals (in this embodiment, Low is defined as the enabled state) are generated. When it is detected that the line synchronization signal becomes Low, the chip select signals (cs_01, cs_03, …, cs_19) for the odd-numbered light-emitting element array chips 300-1, 300-3, …, 300-19 are enabled for the number of light-emitting elements. At the same time, the image data signals (data_01, data_03, …, data_19) for the odd-numbered light-emitting element array chips 300-1, 300-3, …, 300-19 are output for the number of light-emitting elements. When the output of the image data signals (data_01, data_03, …, data_19) for the odd-numbered light-emitting element array chips 300-1, 300-3, …, 300-19 is completed, the chip select signals (cs_02, cs_04, …, cs_20) for the even-numbered light-emitting element array chips 300-2, 300-4, …, 300-20 are then enabled for the number of light-emitting elements. At the same time, the image data signals (data_02, data_04, …, data_20) for the even-numbered light-emitting element array chips 300-2, 300-4, …, 300-20 are output for the number of light-emitting elements. When the output of the image data signals (data_02, data_04, …, data_20) for the even-numbered light-emitting element array chips 300-2, 300-4, …, 300-20 is completed, the line synchronization signal lsync_x of the next line outputs a pulse indicating enable again.

[0057] When printing is performed, a synchronization pulse of the line synchronization signal is output, and while the next pulse is being output, the photosensitive drum 102 rotates by one pixel (21.16 μm in this embodiment), so that the image data of each line is exposed at a resolution of 1200 dpi.

[0058] In FIG. 8, for convenience, the name “-1st” is added to the data on the first line for each light-emitting element array chip, “-2nd” to the data on the second line, and “-3rd” to the data on the third line. Also in FIG. 8, “Chip1” indicates the image data for the light-emitting element array chip 300-1, “Chip2” indicates the image data for the light-emitting element array chip 300-2, “Chip3” indicates the image data for the light-emitting element array chip 300-3, and “Chip4” indicates the image data for the light-emitting element array chip 300-4.

[0059] At this time, the data sent to the even-numbered light-emitting element array chips by the chip data conversion unit 602 includes the aforementioned blank data (data with a density value of 0) with respect to the original image data. The blank data is data with a density value of 0 corresponding to the interval (a predetermined number of lines) between the odd-numbered light-emitting element array chips and the even-numbered light-emitting element array chips. Therefore, using this blank data, the even-numbered light-emitting element array chips and the odd-numbered light-emitting element array chips are adjusted so that they expose the image data in one line. Thereby, adjustment is performed in units of 1 pixel (1 line), and misalignment in the exposed and printed-out image does not occur.

[0060] As shown in FIG. 9, when each light-emitting element array chip is mounted at the reference position with respect to the reference line SL, as shown in FIG. 10, the data of each light-emitting element array chip is exposed and printed in a form that is aligned without misalignment in the longitudinal direction (rotation axis direction) of the photosensitive drum.

[0061] However, in reality, as shown in FIG. 11, when mounting the light-emitting element array chip 300 on the printed circuit board 202, due to the accuracy of the mounting equipment, etc., the light-emitting element array chip 300 may be mounted in a state shifted from the reference position (reference line SL). In FIG. 11, y2, y3, and y4 indicate the mounting misalignment in the drum rotation direction from the reference line SL, and indicate the misalignment amount in units less than 1 pixel.

[0062] In FIG. 11, the light-emitting element array chip 300-1 is mounted in a state where it is not displaced from the reference line SL. Regarding the light-emitting element array chip 300-2, it is mounted in a state where it is displaced by an amount y2 (1 / 3 pixel) from the reference line SL and is displaced upstream in the drum rotation direction. Regarding the light-emitting element array chip 300-3, it is mounted in a state where it is displaced by an amount y3 (2 / 3 pixel) from the reference line SL and is displaced downstream in the drum rotation direction. Regarding the light-emitting element array chip 300-4, it is mounted in a state where it is displaced by an amount y4 (2 / 3 pixel) from the reference line SL and is displaced upstream in the drum rotation direction.

[0063] When exposure and printing are performed using the light-emitting element array chip 300 mounted in the state shown in FIG. 11, as shown in FIG. 12, the data of each light-emitting element array chip is exposed and printed in a state where it is displaced in the drum rotation direction by the above-described displacement amounts y2, y3, and y4. Specifically, with respect to the position of the light-emitting element array chip 300-1 in a non-displaced state, the data of the light-emitting element array chip 300-2 is exposed and printed in a state where it is displaced by an amount y2 (1 / 3 pixel) upstream in the drum rotation direction. Also, the data of the light-emitting element array chip 300-3 is exposed and printed in a state where it is displaced by an amount y3 (2 / 3 pixel) downstream in the drum rotation direction. Also, the data of the light-emitting element array chip 300-4 is exposed and printed in a state where it is displaced by an amount y4 (2 / 3 pixel) upstream in the drum rotation direction.

[0064] In the case of a displacement amount in units of 1 pixel in the drum rotation direction, it is also possible to correct by adjusting the number of lines of blank data by the chip data conversion unit 602 in accordance with the correction between the odd-numbered and even-numbered light-emitting element array chips. However, regarding the mounting displacement of less than 1 pixel, correction cannot be performed by the image processing (adjustment of the number of lines of blank data) in the chip data conversion unit 602.

[0065] Therefore, in this embodiment, when each light-emitting element array chip 300 mounted on the printed circuit board 202 is displaced in the rotational direction orthogonal to the rotational axis direction of the photosensitive drum 102 from the reference position, the amount of displacement is stored in advance in the head information storage unit 610. Then, the CPU 603 of the image controller unit 600 calculates, for each chip, a correction amount for each chip to be exposed at the reference position based on the amount of displacement stored in the head information storage unit 610, and sets the correction amount in the register unit 605. The chip data conversion unit 602 of the image controller unit 600 performs control to adjust the output timing of the divided data signal and chip select signal, etc. as image data to the printed circuit board 202 based on the correction amount set in the register unit 605. Further, the chip data conversion unit 602 transmits the data signal and chip select signal to each light-emitting element array chip at the adjusted output timing.

[0066] When the mounting position of the light-emitting element array chip with respect to the printed circuit board 202 is displaced from the reference position (reference line SL), the chip data conversion unit 602 adjusts the output timing of the signal to the chip by the correction amount calculated based on the amount of displacement. When the mounting position of the light-emitting element array chip is displaced downstream in the drum rotation direction from the reference position, the output timing of the data signal and chip select signal to the chip is adjusted by the correction amount calculated based on the amount of displacement, Delay in the direction. Also, when it is displaced upstream in the drum rotation direction from the reference position, the output timing of the data signal and chip select signal to the chip is adjusted by the correction amount calculated based on the amount of displacement, Advance in the direction.

[0067] Specifically, as shown in FIG. 13, the data signal and chip select signal of the light-emitting element array chip 300-2 are output earlier by a time t2 corresponding to 1 / 3 pixel (displacement amount y2) from the output timing when it was mounted at the originally accurate position (reference position).

[0068] In addition, the data signal and chip select signal of the light-emitting element array chip 300-3 are output with a delay of time t3 corresponding to 2 / 3 pixels (displacement amount y3) from the output timing when it is mounted at the original accurate position (reference position).

[0069] In addition, the data signal and chip select signal of the light-emitting element array chip 300-4 are output earlier by time t4 corresponding to 2 / 3 pixels (displacement amount y4) from the output timing when it is mounted at the original accurate position (reference position).

[0070] The correction of the output timing is adjusted by a high-speed clock when the chip data conversion unit 602 generates the data signal and the chip select signal.

[0071] In this way, by adjusting the output timing of the data signal and the chip select signal to the light-emitting element array chip according to the displacement amount of each light-emitting element array chip, it becomes possible to perform exposure and print output without displacement in the drum rotation direction as shown in FIG. 10.

[0072] According to this embodiment, the mounting deviation (mounting error) of the plurality of light-emitting element array chips 300 mounted on the printed circuit board 202 can be corrected more accurately, and higher image quality output can be realized.

[0073] Note that an example of a flowchart at the time of starting up an image forming apparatus having the above-described mounting deviation correction function will be described with reference to FIGS. 16 and 17. FIG. 16 is a flowchart at the time of starting up the image forming apparatus. FIG. 17 is a flowchart showing details of mounting deviation correction (S1604) in the flowchart of FIG. 16.

[0074] As shown in FIG. 16, when the power of the image forming apparatus is turned on by the user (S1601), although not shown in detail, the system reset of each processing unit in the image forming apparatus is released by a hardware function such as a reset IC (S1602). At that time, the reset of the CPU 603 in the image controller unit 600 is also released, and the CPU 603 starts up (S1603). After the CPU 603 starts up, an OLED (light emitting element array chip) mounting deviation correction flow (the flow shown in FIG. 17) is executed (S1604). After this mounting deviation correction flow is executed, initial settings at the time of various startups by the CPU 603 are executed (S1605). Thereafter, the image forming apparatus enters the standby state and waits for an execution instruction from the user (S1606).

[0075] After the CPU 603 starts up (S1603), the OLED mounting deviation correction flow shown in FIG. 17 is performed. By the CPU 603, information on the amount of deviation in the drum rotation direction during mounting of each light emitting element array chip (OLED) stored in the head information storage unit 610 is read via the communication signal line 660 (1701).

[0076] Then, by the CPU 603, a correction amount corresponding to the amount of deviation of each light emitting element array chip is calculated (S1702).

[0077] The calculated correction amount is converted as a set value of the chip data conversion unit 602 and set in the register for generating the timing of each signal in the chip data conversion unit 602 via the communication signal line 660 (S1703).

[0078] In this embodiment, among the 20 light emitting element array chips mounted on the substrate, four light emitting element array chips 300-1, 300-2, 300-3, and 300-4 are exemplified and described. Among the 20 light emitting element array chips, for the other light emitting element array chips 300-5 to 300-20, similar configurations and timing controls are performed according to the individual amounts of deviation, and similar effects can be obtained.

[0079] In addition, in this embodiment, a configuration is illustrated in which the chip data conversion unit 602 corrects the timing of the chip select signal and the data signal for correcting the mounting deviation in the drum rotation direction. However, the present invention is not limited to this. For example, similar timing correction may be performed by the pulse signal generation unit 705 in each light emitting element array chip. In this case, the correction amount setting from the CPU 603 (S1703 in FIG. 17) is set in the register unit 702 in each light emitting element array chip 300 via the communication signal line 660.

[0080] 〔Embodiment 2〕 An image forming apparatus including an exposure head (exposure device) according to Embodiment 2 will be described with reference to FIGS. 14 and 15.

[0081] In the above-described Embodiment 1, a configuration has been described in which the deviation at the time of mounting each light emitting element array chip in the drum rotation direction is corrected by adjusting the output timing of the data signal and the chip select signal.

[0082] However, in the above-described Embodiment 1, for each light emitting element array chip, a data signal line from the image controller unit is provided independently, and the independent data signal lines are connected respectively. Therefore, the number of wirings between the image controller unit 600 and the printed circuit board 202 and the wiring area on the printed circuit board 202 are required.

[0083] Therefore, in this embodiment, by sharing the data signal line among a plurality of light emitting element array chips, the number of wirings between the image controller unit 600 and the printed circuit board 202 and the wiring area on the printed circuit board 202 are reduced.

[0084] When sharing the data signal line, considering the arrangement and wiring property of the circuit for data generation, the data signal line is shared for the light emitting element array chips adjacent to each other in the rotation axis direction. In this embodiment, the data signal lines of the light emitting element array chip 300-1 and the light emitting element array chip 300-2 adjacent to each other in the rotation axis direction, and the data signal lines of the light emitting element array chip 300-3 and the light emitting element array chip 300-4 are shared respectively.

[0085] Specifically, in FIG. 8, with respect to the data Chip1-x of the light-emitting element array chip 300-1 as the first chip and the data Chip2-x of the light-emitting element array chip 300-2 as the second chip adjacent to the first chip, a common first data signal line is used. Also, with respect to the data Chip3-x of the light-emitting element array chip 300-3 as the first chip and the data Chip4-x of the light-emitting element array chip 300-4 as the second chip adjacent to the first chip, a common second data signal line provided independently of the first data signal line is used. Then, by distributing and using data using the chip select signal, the commonization of the data signal lines for transmitting data signals to a plurality of chips respectively can be achieved.

[0086] In this case, as shown in FIG. 9, if each light-emitting element array chip 300 is mounted on the substrate without mounting deviation, data output to each light-emitting element array chip can be performed without timing correction as shown in FIG. 8.

[0087] However, as shown in FIG. 11, when correcting the mounting deviation in the drum rotation direction, the data signals are output in an overlapping state. Specifically, in the timing chart shown in FIG. 13, looking at the output timing of the data signals of the adjacent light-emitting element array chips 300-1 and 300-2 after timing adjustment, the data Chip1-1st of the first line of the light-emitting element array chip 300-1 and the data Chip2-1st of the first line of the light-emitting element array chip 300-2 are output in an overlapping state due to the timing adjustment for correcting the mounting deviation. Similarly, the data Chip3-1st of the first line of the light-emitting element array chip 300-3 and the data Chip4-1st of the first line of the light-emitting element array chip 300-4 are also output in an overlapping state. At this output timing, the commonization of the data signal lines for transmitting each data signal cannot be achieved.

[0088] Therefore, a common data signal line is connected to a first chip and a second chip adjacent to each other via at least one other chip in the direction of the rotation axis. In this embodiment, the sharing of the data signal line is performed by pairing an odd-numbered light-emitting element array chip adjacent via an even-numbered light-emitting element array chip and an even-numbered light-emitting element array chip adjacent via an odd-numbered light-emitting element array chip. As a result, the correction of the odd-numbered light-emitting element array chip is a correction in the direction of delaying from the original output timing, and the correction of the even-numbered light-emitting element array chip is a correction in the direction of advancing from the original output timing, and the correction directions of the timings are aligned.

[0089] Then, regarding the pair of odd-numbered light-emitting element array chips, the correction amounts of the light-emitting element array chips are compared, and the data of the light-emitting element array chip with a smaller correction amount is output as the first-half data, and the data of the light-emitting element array chip with a larger correction amount is output as the second-half data.

[0090] Also, regarding the pair of even-numbered light-emitting element array chips, the correction amounts of the light-emitting element array chips are compared, and the data of the light-emitting element array chip with a larger correction amount is output as the first-half data, and the data of the light-emitting element array chip with a larger correction amount is output as the second-half data.

[0091] Thereby, it is possible to prevent the data output timings from overlapping due to the difference in the correction amounts.

[0092] The sharing of the data signal line when correcting the mounting deviation in the drum rotation direction in this embodiment will be described with reference to FIGS. 14 and 15. FIG. 14 is a block diagram of the image controller unit 600 and the printed circuit board 202 in the second embodiment. Parts having the same functions as those in the above-described embodiment are given the same part names and the same numbers, and detailed descriptions thereof are omitted here.

[0093] In this example, the common first data signal line 1401 (data_A) is connected to the light-emitting element array chip 300-1 as the first adjacent chip and the light-emitting element array chip 300-3 as the second chip via the light-emitting element array chip 300-2, and is made common. Also, the common second data signal line 1402 (data_B) is connected to the light-emitting element array chip 300-2 as the first adjacent chip and the light-emitting element array chip 300-4 as the second chip via the light-emitting element array chip 300-3, and is made common. Further, in this embodiment, the correction amounts of the light-emitting element array chips that form an odd-numbered pair are compared, and the data of the light-emitting element array chip with a smaller correction amount is output as the first-half data, and the data of the light-emitting element array chip with a larger correction amount is output in the second half. Or the correction amounts of the light-emitting element array chips that form an even-numbered pair are compared, and the data of the light-emitting element array chip with a larger correction amount is output as the first-half data, and the data of the light-emitting element array chip with a larger correction amount is output in the second half.

[0094] As a result of performing the output timing correction as described above, the timing charts of each chip select signal (cs_01 to cs_04) and the data signals (data_A, data_B) are as shown in FIG. 15.

[0095] Regarding the common first data signal line 1401 (data_A), the data signal for the light-emitting element array chip 300-1 and the data signal for the light-emitting element array chip 300-3 are output in a common manner.

[0096] In the case of the mounting deviation as shown in FIG. 11, the light-emitting element array chip 300-1 is mounted at an accurate position (reference position). Therefore, the data signal and the chip select signal of the light-emitting element array chip 300-1 are output at the output timing when it was originally mounted at an accurate position (reference position).

[0097] In addition, the light-emitting element array chip 300-3 is mounted in a state where it is displaced by an amount y3 (2 / 3 pixels) from the reference position and is displaced downstream in the drum rotation direction. Therefore, the data signal and the chip select signal of the light-emitting element array chip 300-3 are output with a delay of time t3 corresponding to 2 / 3 pixels (displacement amount y3) from the output timing when it was mounted at the originally accurate position.

[0098] Therefore, regarding the common first data signal line 1401 (data_A), the data signal of the light-emitting element array chip 300-1 with a small correction amount is output first, and the data signal of the light-emitting element array chip 300-3 is output later.

[0099] In addition, regarding the common second data signal line 1402 (data_B), the data signals for the light-emitting element array chip 300-2 and the light-emitting element array chip 300-4 are output in a shared manner.

[0100] In the case of the mounting deviation as shown in FIG. 11, the light-emitting element array chip 300-2 is mounted in a state where it is displaced by an amount y2 (1 / 3 pixel) from the reference position and is displaced upstream in the drum rotation direction. Therefore, the data signal and the chip select signal of the light-emitting element array chip 300-2 are output earlier by a time t2 corresponding to 1 / 3 pixel (displacement amount y2) from the output timing when it was mounted at the reference position.

[0101] In addition, the light-emitting element array chip 300-4 is mounted in a state where it is displaced by an amount y4 (2 / 3 pixels) from the reference position and is displaced upstream in the drum rotation direction. Therefore, the data signal and the chip select signal of the light-emitting element array chip 300-4 are output earlier by a time t4 corresponding to 2 / 3 pixels (displacement amount y4) from the output timing when it was mounted at the reference position.

[0102] Therefore, regarding the common second data signal line 1402 (data_B), the data signal of the light-emitting element array chip 300-4 with a large correction amount is output first, and the data signal of the light-emitting element array chip 300-2 is output later.

[0103] Also in this embodiment, similar to the above-described embodiments, the mounting deviation (mounting error) of the plurality of light-emitting element array chips 300 mounted on the printed circuit board 202 can be corrected more accurately, and a higher image quality output can be realized.

[0104] Further, in this embodiment, by sharing the data signal lines among the plurality of light-emitting element array chips, the number of wirings between the image controller unit 600 and the printed circuit board 202 and the wiring area on the printed circuit board 202 can be reduced, and the circuit scale of the board can be reduced.

[0105] Note that in this embodiment, among the 20 light-emitting element array chips mounted on the board, four light-emitting element array chips 300-1 to 300-4 are exemplified and described. For the other light-emitting element array chips 300-5 to 300-20, similar effects can be obtained by performing similar configurations and timing controls according to the respective deviation amounts.

[0106] Also in this embodiment, the case where the number of light-emitting element array chips that share the data signal lines is two chips is exemplified and described, but the data signal lines of more chips may be shared. Even in this case, the data signal lines are shared between the odd-numbered light-emitting element array chips and the even-numbered light-emitting element array chips. In other words, if two adjacent chips are connected and shared by a common data signal line from the image controller unit via at least one other chip in the direction of the rotation axis, the number of chips that share the data signal lines can be set as appropriate.

[0107] In addition, the data signal lines of the light-emitting element array chips with odd numbers and the data signal lines of the light-emitting element array chips with even numbers are shared. In other words, the data signal lines of the chips that output the signal of the light-emitting element array chip after delaying the output timing by a time corresponding to the correction amount and the chips that output the signal earlier are shared. Then, the correction amounts of the light-emitting element array chips with odd numbers are compared, and the data signals are output in order from the chip with the smaller correction amount. Also, the correction amounts of the light-emitting element array chips with even numbers are compared, and the data signals are output in order from the chip with the larger correction amount. In other words, the correction amounts of the chips that output after delaying are compared, and the data signals are output in order from the chip with the smaller correction amount. Also, the correction amounts of the chips that output earlier are compared, and the data signals are output in order from the chip with the larger correction amount. Thereby, it is possible to prevent the output timings of the data signals from overlapping through the common data signal line.

[0108] In the above-described embodiment, the configuration in which the image controller unit is provided on a device side different from the exposure head having a printed circuit board is illustrated, but the present invention is not limited thereto. The image controller unit may be provided in the exposure head as the exposure device.

[0109] In the above-described embodiment, a printer is illustrated as the image forming apparatus, but the present invention is not limited thereto. For example, other image forming apparatuses such as a copying machine, a facsimile apparatus, or a multifunction machine that combines these functions may be used. Also, an image forming apparatus that uses a recording material carrier and sequentially superimposes toner images of each color on the recording material carried on the recording material carrier and transfers them is illustrated, but the present invention is not limited thereto. An image forming apparatus that uses an intermediate transfer body, sequentially superimposes toner images of each color on the intermediate transfer body and transfers them, and collectively transfers the toner image carried on the intermediate transfer body to the recording material may be used. By applying the present invention to these image forming apparatuses or the exposure apparatuses used in the image forming apparatuses, the same effects can be obtained.

Explanation of Reference Numerals

[0110] 102... photosensitive drum 201... Light-emitting element group 202... Printed circuit board 203... Rod lens array 204... Housing 300... Light-emitting element array chip 301... Light-emitting element 600... Image controller section 601... Image data generation section 602... Chip data conversion section 603... CPU 604... Synchronization signal generation section 605... Register section 610... Head information storage section 620... Clock signal line 650... Line synchronization signal line 660... Communication signal line 1401~1410... Image data signal line 6301~6320... Chip select signal line 6401~6420... Image data signal line

Claims

1. A substrate on which a first chip having a light-emitting element for exposing a photoreceptor and a second chip having the light-emitting element are mounted in order in the direction of the rotation axis of the photoreceptor; A controller that transmits a signal for controlling the substrate, including a data signal obtained by dividing image data for one line in the direction of the rotation axis of the photoreceptor for each chip, to the substrate; A common data signal line provided on the substrate, connected from the controller to the first chip and the second chip, and transmitting the divided data signal to the first chip and the second chip; A first selection signal line provided on the substrate, connected from the controller to the first chip, and transmitting a selection signal indicating that the divided data signal is for the first chip; A second selection signal line provided on the substrate independently of the first selection signal line, connected from the controller to the second chip, and transmitting a selection signal indicating that the divided data signal is for the second chip; A storage unit that stores the amount of deviation when the chip mounted on the substrate is deviated in the rotational direction orthogonal to the direction of the rotation axis of the photoreceptor from the reference position; and Based on the amount of deviation stored in the storage unit, the controller calculates a correction amount for each chip so that each chip is exposed at the reference position, and adjusts the output timing of the selection signal and the data signal for each chip with the calculated correction amount. Then, the selection signal and the data signal are transmitted to the first chip through the first selection signal line and the common data signal line at the adjusted output timing, and then the selection signal and the data signal are transmitted to the second chip through the second selection signal line and the common data signal line at the adjusted output timing. An exposure apparatus characterized by the above.

2. In addition to the first chip and the second chip, other chips having the light-emitting element are mounted on the substrate, The common data signal line is connected to the adjacent first chip and second chip via at least one other chip in the direction of the rotation axis. The exposure apparatus according to claim 1, characterized by the above.

3. When the mounting position of the chip with respect to the substrate is shifted downstream in the rotation direction from the reference position, the controller adjusts the output timing for outputting the selection signal and the data signal to the chip in a direction to delay by a correction amount calculated based on the shift amount. When the mounting position is shifted upstream in the rotation direction from the reference position, the controller adjusts the output timing for outputting the selection signal and the data signal to the chip in a direction to advance by a correction amount calculated based on the shift amount, and transmits the selection signal and the data signal to the chip at the adjusted output timing. The exposure apparatus according to claim 1 or 2, characterized in that.

4. The shift amount stored in the storage unit is the shift amount when the mounting positions of the respective chips mounted on the substrate are shifted from the reference position in units less than one pixel in the rotation direction of the photoreceptor. The exposure apparatus according to any one of claims 1 to 3, characterized in that.

5. The storage unit is provided on the substrate. The exposure apparatus according to any one of claims 1 to 4, characterized in that.

6. The reference position is the mounting position of one of the plurality of chips mounted on the substrate. The exposure apparatus according to any one of claims 1 to 5, characterized in that.

7. A photoreceptor, An image forming apparatus, comprising: the exposure apparatus according to any one of claims 1 to 6 for exposing the photoreceptor.

Images