Exposure device and image forming device

Abstract

To change a data amount of image data that a light-emitting part of an exposure device can receive per unit time.SOLUTION: An exposure device mounted to an image formation device includes light-emitting means including a plurality of light-emitting devices and receiving means connected to a plurality of signal lines and receiving image data for controlling light emission by the plurality of light-emitting devices from the image formation device. The receiving means acquires determination information and determines at least one signal line to be used for receiving the image data from the plurality of signal lines on the basis of the acquired determination information.SELECTED DRAWING: Figure 14

Description

[Technical Field]

[0001] The present invention relates to an exposure device having a plurality of light-emitting elements, and an image forming apparatus that forms an image using the exposure device. [Background technology]

[0002] Electrophotographic image forming apparatuses expose a rotating photoconductor to light to form an electrostatic latent image on the photoconductor, and then develop the electrostatic latent image with toner to form an image. The direction parallel to the rotation axis of the photoconductor is referred to as the main scanning direction. Patent Document 1 discloses an image forming apparatus that performs exposure of one line in the main scanning direction using an exposure device with a plurality of light-emitting elements arranged in the main scanning direction. Patent Document 1 also discloses an exposure device equipped with a substrate on which a light-emitting chip is mounted, in which electrodes, an organic electroluminescence (EL) film, and a circuit unit for emitting light from the organic EL film are formed on a silicon wafer. Metal pads are formed on the silicon wafer, and the pads are connected by wires (signal lines) to metal pads formed on the substrate on which the silicon wafer is mounted. The circuit unit applies voltage to the electrodes based on image data transmitted via the wires from a control unit of the image forming apparatus, thereby emitting light from the organic EL film. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-35765 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, the faster the image formation speed in the image forming apparatus, the greater the amount of image data transmitted to the circuit section per unit time. One possible method for increasing the amount of image data transmitted per unit time is to transmit the image data in parallel using two signal lines. In such a method, two sets of wire bonding pads and wires are used. It has also been considered to reduce the manufacturing cost of the light-emitting chips by sharing the same light-emitting chips between an image forming apparatus having a first image formation speed and an image forming apparatus having a second image formation speed slower than the first speed.

[0005] However, when an exposure device with two sets of wire bonding pads and wires is installed in an image forming apparatus whose image forming speed is the second speed, the following problem may occur. Specifically, even though one set of wire bonding pads and wires is sufficient for image formation at the second speed, there is a possibility that wire bonding pads and wires will be installed in vain. In other words, the cost of the image forming apparatus will increase.

[0006] In view of the above-mentioned problems, an object of the present invention is to provide a technique for suppressing an increase in the cost of an image forming apparatus. [Means for solving the problem]

[0007] According to one aspect of the present disclosure, an exposure device mounted on an image forming apparatus includes a plurality of light emitting elements and a plurality of signal lines connected to the light emitting elements. Multiple connections arranged in a manner that allows and a receiving unit that receives image data for controlling the light emission of the plurality of light-emitting elements from the image forming apparatus, the receiving unit acquiring determination information and performing a light emission control based on the acquired determination information. Before Used to receive the image data Belief Line Number of Determine the following. [Effects of the Invention]

[0008] According to the present invention, it is possible to prevent the cost of the image forming apparatus from increasing. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of an image forming apparatus according to an embodiment. [Figure 2] FIG. 2 illustrates an exposure head and photoreceptor, according to one embodiment. [Figure 3] FIG. 2 illustrates a printed circuit board for an exposure head, according to one embodiment. [Figure 4] 1 is an illustration of the arrangement of light emitting elements within a light emitting chip according to one embodiment. [Figure 5] 1 is a plan view of a light-emitting chip according to one embodiment. [Figure 6] 1 is a cross-sectional view of a light-emitting chip according to one embodiment. [Figure 7] FIG. 2 is a configuration diagram of a first printed circuit board using a light-emitting chip according to an embodiment. [Figure 8] 10A and 10B are diagrams showing examples of signals on each signal line when accessing a register of a light-emitting chip according to one embodiment. [Figure 9] 10A and 10B are diagrams showing examples of signals on each signal line when image data is transmitted to the light-emitting chips on the first printed circuit board according to one embodiment. [Figure 10] FIG. 10 is a diagram illustrating the configuration of a second printed circuit board using a light-emitting chip according to an embodiment. [Figure 11] 10A and 10B are diagrams showing examples of signals on each signal line when image data is transmitted to a light-emitting chip on a second printed circuit board according to an embodiment. [Figure 12] FIG. 2 is a functional block diagram of a light-emitting chip, according to one embodiment. [Figure 13] FIG. 2 is a block diagram of a current driver according to one embodiment. [Figure 14] 10 is a flowchart of a process performed by an image controller, according to one embodiment. [Figure 15] 10A and 10B are diagrams showing examples of signals on each signal line when image data is transmitted to the light-emitting chips on the first printed circuit board according to one embodiment. [Figure 16]10A and 10B are diagrams showing examples of signals on each signal line when image data is transmitted to a light-emitting chip on a second printed circuit board according to an embodiment. [Figure 17] FIG. 2 is a functional block diagram of a light-emitting chip, according to one embodiment. [Figure 18] 10 is a flowchart of a process performed by an image controller, according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0011] First Embodiment 1 is a schematic diagram of an image forming apparatus according to this embodiment. A reading unit 100 optically reads an original placed on a platen and generates image data representing the reading result. An image creating unit 103 forms an image on a sheet based on the image data generated by the reading unit 100 or based on image data received from an external device via a network, for example.

[0012] The image forming unit 103 includes image forming units 101a, 101b, 101c, and 101d. The image forming units 101a, 101b, 101c, and 101d form black, yellow, magenta, and cyan toner images, respectively. The image forming units 101a, 101b, 101c, and 101d have the same configuration and are collectively referred to as the image forming unit 101 below. The photoconductor 102 of the image forming unit 101 is rotated clockwise in the drawing during image formation. The charger 107 charges the photoconductor 102. The exposure head 106, which is an exposure device, exposes the photoconductor 102 to light according to image data, forming an electrostatic latent image on the photoconductor 102. The developer 108 develops the electrostatic latent image on the photoconductor 102 with toner. The toner image on the photoreceptor 102 is transferred onto a sheet transported on a transfer belt 111. By transferring the toner images of the photoreceptors 102 onto a sheet in an overlapping manner, it is possible to reproduce colors different from black, yellow, magenta, and cyan.

[0013] The conveying unit 105 controls the feeding and transport of sheets. Specifically, the conveying unit 105 feeds a sheet from a designated unit among the internal storage units 109a and 109b, the external storage unit 109c, and the manual feed unit 109d to a transport path of the image forming apparatus. The fed sheet is transported to the registration rollers 110. The registration rollers 110 transport the sheet onto the transfer belt 111 at a predetermined timing so that the toner images on the photoconductors 102 are transferred to the sheet. As described above, the toner image is transferred to the sheet while it is transported on the transfer belt 111. The fixing unit 104 fixes the toner image to the sheet by applying heat and pressure to the sheet onto which the toner image has been transferred. After the toner image is fixed, the sheet is discharged to the outside of the image forming apparatus by the discharge rollers 112.

[0014] 2(A) and 2(B) show the photoconductor 102 and the exposure head 106. The exposure head 106 has a light-emitting point group 201, a printed circuit board 202 on which the light-emitting point group 201 is mounted, a rod lens array 203, and a housing 204 that holds the rod lens array 203 and the printed circuit board 202. The rod lens array 203 focuses the light emitted from the light-emitting point group 201 onto the photoconductor 102, and forms an imaging spot of a predetermined size on the photoconductor 102.

[0015] 3(A) and 3(B) show the printed circuit board 202. FIG. 3(A) shows the surface on which the connector 305 is mounted, and FIG. 3(B) shows the surface on which the light-emitting point group 201 is mounted (the surface opposite to the surface on which the connector 305 is mounted). In this embodiment, the light-emitting point group 201 includes 20 light-emitting chips 400-1 to 400-20. The light-emitting chips 400-1 to 400-20 are arranged in two staggered rows along the main scanning direction. In the following description, the light-emitting chips 400-1 to 400-20 are also collectively referred to as light-emitting chips 400. The light-emitting chips 400 may also be referred to as a light-emitting unit. Each light-emitting chip 400 has a plurality of light-emitting points (light-emitting elements). Each light-emitting chip 400 on the printed circuit board 202 is connected to an image controller 700 (FIG. 7) serving as a control unit via a connector 305.

[0016] FIG. 4 is an explanatory diagram of a light-emitting chip 400 and the arrangement of light-emitting points 602 provided on the light-emitting chip 400. One light-emitting chip 400 has multiple sets of 748 light-emitting points 602 arranged along the main scanning direction. The multiple sets are arranged along the sub-scanning direction perpendicular to the main scanning direction. In the following description, the number of sets is assumed to be four as an example. That is, in the following exemplary embodiment, the light-emitting chip 400 has four sets of 748 light-emitting points 602 arranged along the main scanning direction, i.e., a total of 2992 light-emitting points 602. The pitch between adjacent light-emitting points 602 in the main scanning direction is approximately 21.16 μm, which corresponds to a resolution of 1200 dpi. Therefore, the length of one set of 748 light-emitting points 602 in the main scanning direction is approximately 15.8 mm. The pitch between adjacent light-emitting points 602 in the sub-scanning direction (length P in FIG. 4) is also approximately 21.16 μm, which corresponds to a resolution of 1200 dpi. Furthermore, the pitch (length L in FIG. 4) between the light-emitting points 602 of two adjacent light-emitting chips 400 in the main scanning direction is also about 21.16 μm, which corresponds to a resolution of 1200 dpi.

[0017] 5 is a plan view of the light-emitting chip 400. The light-emitting chip 400 has a plurality of light-emitting points 602 formed on a light-emitting substrate 402, which is, for example, a silicon substrate. The light-emitting substrate 402 is also provided with a circuit unit 406 for controlling the plurality of light-emitting points 602. Signal lines for communicating with the image controller 700, power lines for connecting to a power source, and ground lines for connecting to ground are connected to the pads 408-1 to 408-10. The signal lines, power lines, and ground lines are, for example, wires made of gold.

[0018] FIG. 6 shows a portion of the cross section taken along line AA in FIG. 5. A plurality of lower electrodes 504 are formed on the light-emitting substrate 402. A gap of length d is provided between two adjacent lower electrodes 504. A light-emitting layer 506 is provided on the lower electrodes 504, and an upper electrode 508 is provided on the light-emitting layer 506. The upper electrode 508 is a common electrode for the plurality of lower electrodes 504. When a predetermined voltage is applied between the lower electrode 504 and the upper electrode 508, a current flows from the lower electrode 504 to the upper electrode 508, causing the light-emitting layer 506 to emit light. Therefore, the region of the light-emitting layer 506 corresponding to the region of one lower electrode 504 corresponds to one light-emitting point 602. That is, in this embodiment, the light-emitting substrate 402 includes a plurality of light-emitting points. The light-emitting points may also be called light-emitting portions.

[0019] The light-emitting layer 506 may be made of, for example, an organic EL film. Alternatively, the light-emitting layer 506 may be made of, for example, an inorganic EL film. The upper electrode 508 is made of a transparent electrode such as indium tin oxide (ITO) so as to transmit the emission wavelength of the light-emitting layer 506. In this embodiment, the entire upper electrode 508 transmits the emission wavelength of the light-emitting layer 506, but it is not necessary for the entire upper electrode 508 to transmit the emission wavelength. Specifically, it is sufficient that the region through which light from each light-emitting point 602 is emitted transmits the emission wavelength.

[0020] In the present embodiment, the light-emitting layer 506 is common to all the lower electrodes 504 provided in the light-emitting chip 400; however, this is not limited thereto. For example, a configuration may be adopted in which a first plurality of lower electrodes 504 among the plurality of lower electrodes 504 provided in the light-emitting chip 400 are covered with a first light-emitting layer 506, and a second plurality of lower electrodes 504 among the plurality of lower electrodes 504 provided in the light-emitting chip 400 are covered with a second light-emitting layer 506. Even in such a configuration, a region of the light-emitting layer 506 corresponding to a region of one lower electrode 504 corresponds to one light-emitting point 602. Alternatively, a light-emitting layer 506 may be individually provided for each of the plurality of lower electrodes 504 provided in the light-emitting chip 400. Even in such a configuration, a region of the light-emitting layer 506 corresponding to a region of one lower electrode 504 corresponds to one light-emitting point 602.

[0021] FIG. 7 shows a printed circuit board 202-1 (first printed circuit board) on which light-emitting chips 400-1 to 400-20 are provided. The printed circuit board 202-1 is used for a type of exposure head 106 that supports a slower image formation speed than the printed circuit board 202-2 (second printed circuit board) described below. In the following description, the printed circuit board 202-1 is assumed to be a printed circuit board for the exposure head 106 of an image forming apparatus having an image formation speed of 200 mm / s. The printed circuit board 202-2 is assumed to be a printed circuit board for the exposure head 106 of an image forming apparatus having an image formation speed of 400 mm / s. The image formation speed corresponds to, for example, the circumferential speed of the photosensitive member 102. Furthermore, in the following description, the resolution in the sub-scanning direction is assumed to be 1200 dpi (approximately 21.16 μm).

[0022] The data switching unit 705 and each light-emitting chip 400 are connected by a plurality of signal lines (wires). Specifically, the data switching unit 705 and the light-emitting chip 400-n (n is an integer from 1 to 20) are connected by a signal line DATAn-1 and a signal line WRITEn. The signal line DATAn-1 is used by the data switching unit 705 to transmit image data to the light-emitting chip 400-n. The signal line WRITEn is used by the data switching unit 705 to write control data to a register of the light-emitting chip 400-n. The signal line WRITEn may also be called a control line because it transmits control data.

[0023] The data switching unit 705 and all the light-emitting chips 400 are connected by one signal line CLK, one signal line SYNC, and one signal line EN. The signal line CLK is used to transmit a clock signal for transmitting data on the signal lines DATAn-1 and WRITEn. The data switching unit 705 outputs a clock signal generated based on a reference clock signal from the clock generating unit 702 to the signal line CLK. The signals transmitted to the signal lines SYNC and EN will be described later.

[0024] The CPU 701 controls the entire image forming apparatus. The image data generation unit 703 performs various image processing, such as halftoning, on image data received from the reading unit 100 or an external device to generate image data for controlling the on / off of the light-emitting points 602 of each light-emitting chip 400. The image data generation unit 703 transmits the generated image data to the data switching unit 705. The register access unit 704 receives control data to be written to the registers in each light-emitting chip 400 from the CPU 701 and transmits it to the data switching unit 705. As shown in FIG. 7 , a pull-down resistor 706 is provided on the printed circuit board 202-1. One end of the pull-down resistor 706 is connected to the CPU 701 via a control line PORT. The other end of the pull-down resistor 706 is connected to a predetermined potential, which is ground potential in this example. The CPU 701 can determine, based on the potential of the control line PORT, that the exposure head 106 mounted on the image forming apparatus is of the first type, having the printed circuit board 202-1.

[0025] FIG. 8 shows the signals on each signal line when control data is written to the register of the light-emitting chip 400. An enable signal that is at a high level during communication and indicates that communication is in progress is output to the signal line EN. The data switching unit 705 transmits a start bit to the signal line WRITEn in synchronization with the rising edge of the enable signal. Next, the data switching unit 705 transmits a write identification bit indicating a write operation, and then transmits the address of the register to which the control data is to be written (4 bits in this example) and the control data (8 bits in this example). When writing to the register, the data switching unit 705 sets the frequency of the clock signal transmitted to the signal line CLK to, for example, 3 MHz.

[0026] FIG. 9 shows the signals on each signal line when image data is transmitted to each light-emitting chip 400 on the printed circuit board 202-1. A line synchronization signal indicating the exposure timing of one line on the photosensitive element 102 is output to the signal line SYNC. Since the image formation speed of the printed circuit board 202-1 is 200 mm / s and the resolution in the sub-scanning direction is 1200 dpi (approximately 21.16 μm), the line synchronization signal is output approximately every 105.8 μs. The data switching unit 705 transmits image data to the signal line DATAn-1 in synchronization with the rising edge of the line synchronization signal. In this embodiment, each light-emitting chip 400 has 2992 light-emitting points 602, and therefore, image data indicating whether each of the 2992 light-emitting points 602 is emitting or not emitting light must be transmitted within a period of approximately 105.8 μs. In this example, in order to transmit image data for a total of 2,992 light-emitting points 602 within a period of approximately 105.8 μs, as shown in FIG. 9, when transmitting image data, the data switching unit 705 sets the frequency of the clock signal transmitted to the signal line CLK to 30 MHz.

[0027] FIG. 10 shows a printed circuit board 202-2 (second printed circuit board) on which the light-emitting chips 400-1 to 400-20 are provided. As described above, the image formation speed of the printed circuit board 202-2 is 400 mm / s. The light-emitting chip 400 is the same as that used in the printed circuit board 202-1. The following describes differences from the printed circuit board 202-1 shown in FIG. 7. Each light-emitting chip 400 of the printed circuit board 202-2 receives image data via both signal lines DATAn-1 and DATAn-2. Therefore, the data switching unit 705 and the light-emitting chip 400-n are also connected via the signal line DATAn-2. Furthermore, as shown in FIG. 10, the printed circuit board 202-2 is provided with a pull-up resistor 707 instead of the pull-down resistor 706 of the printed circuit board 202-1. One end of the pull-up resistor 707 is connected to the CPU 701 via a control line PORT. The other end of the pull-up resistor 707 is connected to a predetermined potential different from the ground potential. Based on the potential of the control line PORT, the CPU 701 can determine that the exposure head 106 mounted on the image forming apparatus is of a second type that has a printed circuit board 202-2.

[0028] FIG. 11 shows the signals on each signal line when image data is transmitted to each light-emitting chip 400 on the printed circuit board 202-2. A line synchronization signal indicating the exposure timing of one line on the photosensitive element 102 is output to the signal line SYNC. Since the image formation speed of the printed circuit board 202-2 is 400 mm / s and the resolution in the sub-scanning direction is 1200 dpi (approximately 21.16 μm), the line synchronization signal is output approximately every 52.8 μs. The data switching unit 705 transmits image data on the signal lines DATAn-1 and DATAn-2 in synchronization with the rising edge of the line synchronization signal. When transmitting image data over a single signal line DATAn-1, as with the printed circuit board 202-1, the data switching unit 705 must set the frequency of the clock signal transmitted over the signal line CLK to 60 MHz in order to achieve an image formation speed of 400 mm / s. In this embodiment, since image data is transmitted over two signal lines, the amount of image data that can be transmitted per unit time can be doubled while maintaining the clock signal frequency at 30 MHz, the same as in the case of the printed circuit board 202-1. This configuration allows the amount of image data that the light-emitting chip 400 can receive per unit time to be doubled without excessively increasing the clock signal frequency, i.e., the image data transmission speed. Note that the process for accessing the register is the same as in the case of the printed circuit board 202-1 shown in FIG. 8.

[0029] 12 is a functional block diagram of one light-emitting chip 400-n mounted on the printed circuit boards 202-1 and 202-2. As also shown in FIG. 5, the light-emitting chip 400 has ten pads 408-1 to 408-10. The pads 408-1 and 408-2 are connected to a power supply voltage VCC via a power supply line. Power is supplied from this power supply voltage VCC to each circuit of the circuit unit 406 of the light-emitting chip 400. The pads 408-3 and 408-4 are connected to ground via a ground line. Each circuit of the circuit unit 406 and the upper electrode 508 are connected to ground via the pads 408-3 and 408-4. The signal lines CLK, SYNC, DATAn-1, and DATAn-2 are connected to the image data holding unit 1103 via the pads 408-5 to 408-8. The image data holding unit 1103 and pads 408-5 to 408-8 are connected by signal lines corresponding to the signal lines CLK, SYNC, DATAn-1, and DATAn-2, respectively. The signal lines EN and WRITEn are connected to the register 1102 via pads 408-9 and 408-10. The signal line CLK is also input to the register 1102. The register 1102 and pads 408-9 and 408-10 are connected by signal lines corresponding to the signal lines EN and WRITEn, respectively.

[0030] A pull-down resistor 1205 is provided on the signal line in the circuit unit 406 connecting the image data holding unit 1103 and the pad 408-8. This is because, in the case of the printed circuit board 202-1, even if a signal line DATAn-2 connecting the data switching unit 705 and the pad 408-8 of the light-emitting chip 400-n is not provided, the potential of the signal line in the circuit unit 406 connected to the pad 408-8 is fixed to a predetermined value, for example, ground potential. In this embodiment, the printed circuit board 202-1 is provided with a pad for the signal line DATAn-2, but is not provided with a signal line DATAn-2 connecting the pad to the pad 408-8. As a result, the cost of the signal line DATAn-2 can be reduced. For example, the printed circuit board 202-1 may not be provided with a pad for the signal line DATAn-2. As a result, the cost of the pad and the signal line DATAn-2 can be reduced.

[0031] As described above, the register 1102 stores control data indicating control information. In this embodiment, the control information includes information for controlling the light emission intensity of each light-emitting point 602. The control information also includes determination information indicating whether image data is to be transmitted using only the signal line DATAn-1 or both the signal lines DATAn-1 and DATAn-2. As described above, the CPU 701 of the image controller 700 determines whether the printed circuit board is the printed circuit board 202-1 or the printed circuit board 202-2 based on the potential of the control line PORT. If the CPU 701 determines that the printed circuit board is the printed circuit board 202-1, it stores data (determination information) indicating that image data will be transmitted using one signal line in the register 1102. On the other hand, if the CPU 701 determines that the printed circuit board is the printed circuit board 202-2, it stores data (determination information) indicating that image data will be transmitted using two signal lines in the register 1102.

[0032] When determination information indicating that image data should be transmitted over one signal line is stored in the register 1102, the image data holding unit 1103 receives and stores the image data via signal line DATAn-1. Similarly, when determination information indicating that image data should be transmitted over two signal lines is stored in the register 1102, the image data holding unit 1103 receives and stores the image data via signal lines DATAn-1 and DATAn-2. The image data holding unit 1103 is a receiving unit that receives image data. When the image data holding unit 1103 receives image data for exposing the photoconductor 102, the image data holding unit 1103 generates drive signals that control the light emission of each light-emitting point 602 based on the image data and outputs the drive signals to the current driving unit 1104.

[0033] FIG. 13 shows the configuration of the current driver 1104. Note that FIG. 13 shows only a circuit portion corresponding to one light-emitting point 602. The light-emitting chip 400 according to this embodiment has a total of 2992 light-emitting points 602, and therefore, the light-emitting chip 400 has only 2992 circuit portions shown in FIG. 13. The DAC 1501 outputs an analog voltage corresponding to a digital value indicated by control data stored in the register 1102. The FET 1502 is a P-channel MOSFET, and its source terminal is connected to a power supply voltage VCC and its drain terminal is connected to the source terminal of the FET 1503. The analog voltage output by the DAC 1501 is applied to the gate terminal of the FET 1502. The FET 1503 is also a P-channel MOSFET, and its drain terminal is connected to the lower electrode 504. A drive signal output from the image data storage unit 1103 is input to the gate terminal of the FET 1503. The drive signal is a binary signal of high level or low level, and when it is at high level, the FET 1503 is on, and when it is at low level, the FET 1503 is off.

[0034] While FET 1503 is on, a current flows from the power supply voltage VCC to the light-emitting layer 506 via FET 1502 and FET 1503, causing the light-emitting points 602 to emit light. The light emission intensity of the light-emitting points 602 changes according to the current flowing through the light-emitting layer 506, and the value of this current is controlled by the analog voltage output by DAC 1501. In other words, the light emission intensity of each light-emitting point 602 is controlled by control data stored in register 1102. Note that the control data may individually indicate the digital values ​​of DAC 1501 corresponding to each light-emitting point 602, or may indicate one digital value for each group of multiple light-emitting points 602.

[0035] FIG. 14 is a flowchart of a process executed by the image controller 700 when a user requests printing. In S10, the image controller 700 determines the potential of the control line PORT and, based on this, determines the type of the printed circuit board 202, i.e., whether it is the printed circuit board 202-1 or the printed circuit board 202-2. Note that different types of printed circuit boards 202 correspond to different types of exposure heads 106. In S11, the image controller 700 writes determination information to the register 1102 of each light-emitting chip 400. The determination information is information for determining the signal line to be used for transmitting image data. As described above, in the present embodiment, in the case of the printed circuit board 202-1, the signal line used for transmitting image data is one, DATAn-1, and in the case of the printed circuit board 202-2, the signal lines used for transmitting image data are two, DATAn-1 and DATAn-2. Next, in S12, the image controller 700 sets the digital values ​​to be set in the DACs 1501 corresponding to each light-emitting point 602 in the register 1102. Note that the order of S11 and S12 may be reversed. Next, when it is time to start image formation, image controller 700 transmits image data in S13 and starts exposing photoconductor 102. In S14, image controller 700 determines whether image formation is complete, and if image formation is not complete, repeats the process from S13. On the other hand, if image formation is complete, image controller 700 ends the process of FIG. 14.

[0036] As described above, the image controller 700 determines the type of the printed circuit board 202, i.e., the type of the exposure head 106, and determines the signal lines to be used for transmitting image data to the exposure head 106 based on the type. The image controller 700 also stores, in the register 1102 of the light-emitting chip 400, determination information that the light-emitting chip 400 uses to determine one or more signal lines to be used for transmitting image data. The image data holding unit 1103 of each light-emitting chip 400 determines one or more signal lines to be used for receiving image data based on the determination information stored in the register 1102 of the same light-emitting chip 400. This configuration allows each light-emitting chip 400 to change the amount of image data that it can receive per unit time. Therefore, it is possible to use the same light-emitting chip 400 for multiple types of exposure heads 106 with different image formation speeds, while preventing an increase in the cost of the image forming apparatus.

[0037] In this embodiment, since the number of types of printed circuit boards 202, i.e., the number of types of exposure heads 106, is two, one resistor (pull-down resistor 706, pull-up resistor 707) is used to determine the type of printed circuit board 202. However, the number of types of exposure heads 106 may be any number greater than or equal to three. For example, if the number of types of exposure heads 106 is three or four, the types of exposure heads 106 can be determined by providing two resistors on the printed circuit board 202. Furthermore, instead of using a circuit including resistors to determine the type of exposure head 106, a non-volatile memory device storing information indicating the type of exposure head 106 can also be provided. In this case, the image controller 700 determines the type of exposure head 106 based on the information stored in the non-volatile memory device on the printed circuit board 202.

[0038] Furthermore, in this embodiment, the number of signal lines is set to one or two depending on the type of exposure head 106. However, the number of signal lines used to transmit image data is not limited to one or two. For example, in the case of a first type of exposure head 106, a first number of signal lines may be used to transmit image data, and in the case of a second type of exposure head 106, the number of signal lines used to transmit image data may be a second number different from the first number. Here, the first number and the second number are any numbers equal to or greater than one. The same applies when the number of types of exposure heads 106 is three or more.

[0039] Second Embodiment Next, the second embodiment will be described, focusing on the differences from the first embodiment. In the first embodiment, after determining the type of the exposure head 106, the image controller 700 writes determination information to the register 1102 of each light-emitting chip 400 so that the image data holding unit 1103 can determine the signal line to be used for transmitting image data (S11 in FIG. 14). In this embodiment, before transmitting the image data, an identification bit indicating determination information for determining the signal line to be used for transmitting the image data is transmitted to each light-emitting chip 400, thereby notifying the signal line to be used for transmitting the image data.

[0040] 15 shows the signals on each signal line when image data is transmitted to the printed circuit board 202-1. The data switching unit 705 first transmits an identification bit to the signal line DATAn-1 in synchronization with the rising edge of the line synchronization signal. In this embodiment, the identification bit is two bits, and when both bits are at a high level, this indicates that the signal line used to transmit the image data is the signal line DATAn-1. After transmitting the identification bit, the data switching unit 705 uses the signal line DATAn-1 to transmit image data for a total of 2,992 light-emitting points 602.

[0041] FIG. 16 shows the signals on each signal line when transmitting image data to the printed circuit board 202-2. The data switching unit 705 first transmits an identification bit to the signal line DATAn-1 in synchronization with the rising edge of the line synchronization signal. While transmitting the identification bit, any data value can be transmitted to the signal line DATAn-2. In this embodiment, the first bit of the identification bit being high and the second bit being low indicates that the signal lines used to transmit image data are the signal lines DATAn-1 and DATAn-2. After transmitting the identification bit, the data switching unit 705 transmits image data for a total of 2,992 light-emitting points 602 using the signal lines DATAn-1 and DATAn-2. In this manner, the signal lines for transmitting the identification bit are predetermined. Furthermore, the signal line DATAn-1 used to transmit the identification bit can be configured to always be used to transmit image data. The same applies when three or more signal lines are used to transmit image data.

[0042] FIG. 17 is a functional block diagram of one light-emitting chip 400-n mounted on the printed circuit boards 202-1 and 202-2 according to this embodiment. The following description focuses on differences from the first embodiment shown in FIG. 12. In this embodiment, the signal lines CLK, SYNC, DATAn-1, and DATAn-2 are connected to the data discrimination unit 1801. The data discrimination unit 1801 and the image data storage unit 1103 are connected by signal lines corresponding to the signal lines CLK, SYNC, DATAn-1, and DATAn-2. The data discrimination unit 1801 outputs a clock signal and a line synchronization signal received via the signal lines CLK and SYNC to the image data storage unit 1103. The data discrimination unit 1801 also determines the signal line used to transmit image data based on an identification bit received in synchronization with the line synchronization signal. If the signal line used to transmit image data is only the signal line DATAn-1, the data discrimination unit 1801 outputs the image data received via the signal line DATAn-1 to the image data storage unit 1103. On the other hand, when the signal lines used to transmit image data are signal lines DATAn-1 and DATAn-2, the data discrimination unit 1801 outputs the image data received via signal lines DATAn-1 and DATAn-2 to the image data holding unit 1103. In this way, the data discrimination unit 1801 and the image data holding unit 1103 correspond to a receiving unit that receives image data.

[0043] FIG. 18 is a flowchart of the process executed by the image controller 700 when a print request is received from a user. In S20, the image controller 700 determines the potential of the control line PORT and, based on this, determines the type of the printed circuit board 202, i.e., whether it is printed circuit board 202-1 or printed circuit board 202-2. Note that different types of printed circuit boards 202 correspond to different types of exposure heads 106. In S21, the image controller 700 sets the digital values ​​to be set in the DACs 1501 corresponding to each light-emitting point 602 in the registers 1102. Next, when it is time to start image formation, the image controller 700 transmits an identification bit to the signal line DATAn-1 in S22, and then transmits one line of image data in S23. Note that the signal line for transmitting the image data is determined depending on the type of exposure head 106 determined in S20. In S24, the image controller 700 determines whether image formation is complete. If image formation is not complete, the process repeats from S22. On the other hand, if image formation is complete, the image controller 700 ends the processing of FIG.

[0044] In this embodiment, too, the amount of image data that each light-emitting chip 400 can receive per unit time can be changed. Therefore, the same light-emitting chip 400 can be used for multiple types of exposure heads 106 with different image formation speeds. Furthermore, in this embodiment, there is no need to write determination information to the register 1102 of each light-emitting chip 400 at the start of image formation, so the time required for image formation can be shortened.

[0045] In each of the above embodiments, the light-emitting chip 400 determines the signal line to be used for receiving image data based on the determination information and acquires the determination information from the image forming apparatus. Specifically, in the first embodiment, the image controller 700 of the image forming apparatus writes the determination information to the register 1102 of the light-emitting chip 400, thereby allowing the light-emitting chip 400 to acquire the determination information. In the second embodiment, the light-emitting chip 400 receives, or acquires, the determination information via the signal line before receiving the image data. In the first and second embodiments, the image controller 700 of the image forming apparatus determines the signal line to be used for transmitting image data based on information stored in circuits, such as pull-up resistors / pull-down resistors, and nonvolatile memory devices, provided on the printed circuit board 200, and generates the determination information. However, instead of acquiring the determination information from the image forming apparatus, each light-emitting chip 400 may determine the signal line to be used for receiving image data based on information stored in circuits, such as pull-up resistors / pull-down resistors, and nonvolatile memory devices provided on the printed circuit board 200. In this case, the image controller 700 determines the signal line to be used for transmitting image data based on information stored in a circuit provided on the printed circuit board 200 or a non-volatile memory device, but does not need to notify each light-emitting chip 400 of the determination information.

[0046] In the above embodiments, specific numerical values ​​are used for explanation purposes. However, these specific numerical values ​​are merely examples, and the present invention is not limited to the specific numerical values ​​used in the embodiments. Specifically, the number of light-emitting chips 400 provided on one printed circuit board 202 is not limited to 20 and can be any number equal to or greater than one. Furthermore, the number of light-emitting points 602 included in each light-emitting chip 400 is not limited to 2992 and can be any number. In the present embodiment, one light-emitting chip 400 has four sets of 748 light-emitting points arranged along the main scanning direction, but the number of sets can be any number equal to or greater than one. Furthermore, the light-emitting points 602 are arranged at a pitch of approximately 21.16 μm in the main scanning direction, which corresponds to a resolution of 1200 dpi. However, the arrangement interval of the light-emitting points 602 may also be other values.

[0047] In the above embodiment, the image forming apparatus transfers the toner images formed on the photoconductors 102 onto a sheet conveyed on the transfer belt 111. However, the image forming apparatus may transfer the toner images on the photoconductors 102 onto a sheet via an intermediate transfer body. The image forming apparatus may be a color image forming apparatus that forms an image using toners of multiple colors, or a monochrome image forming apparatus that forms an image using toner of one color.

[0048] [Other embodiments] The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0049] The disclosure of this embodiment includes the following configuration. (Configuration 1) An exposure device mounted in an image forming apparatus, a light-emitting unit including a plurality of light-emitting elements and a receiving unit connected to a plurality of signal lines and configured to receive image data for controlling light emission of the plurality of light-emitting elements from the image forming device; The receiving means acquires determination information, and determines at least one signal line to be used for receiving the image data from among the plurality of signal lines based on the acquired determination information. (Configuration 2) 2. The exposure device according to configuration 1, wherein the receiving means acquires the determination information from the image forming device. (Configuration 3) the light emitting means further includes storage means for storing the determination information; 3. The exposure apparatus according to configuration 1 or 2, wherein the receiving means acquires the determination information stored in the storage means by the image forming apparatus. (Configuration 4) 4. The exposure apparatus according to configuration 3, wherein the determination information is stored in the storage means by the image forming apparatus via a signal line different from the plurality of signal lines. (Configuration 5) 3. The exposure device according to configuration 1 or 2, wherein the receiving means acquires the determination information by receiving the determination information from the image forming device via a first signal line among the plurality of signal lines. (Configuration 6) The exposure apparatus according to configuration 5, wherein the receiving means receives the determination information via the first signal line, and then receives the image data via the at least one signal line determined based on the determination information. (Configuration 7) 7. The exposure apparatus according to configuration 5 or 6, wherein the at least one signal line includes the first signal line. (Configuration 8) 8. An exposure device according to any one of configurations 5 to 7, wherein the second signal line is configured so that the potential of the second signal line becomes a predetermined value when the signal line from the image forming device is not connected to a second signal line different from the first signal line among the plurality of signal lines. (Configuration 9) The exposure device described in any one of configurations 1 to 8, further comprising a circuit for causing the image forming device to determine the at least one signal line, or a memory device for storing information for causing the image forming device to determine the at least one signal line. (Configuration 10) The image forming apparatus further includes a circuit for causing the image forming apparatus to determine the at least one signal line, or a memory device for storing information for causing the image forming apparatus to determine the at least one signal line, 2. The exposure apparatus according to configuration 1, wherein the receiving means acquires the determination information based on the information stored in the circuit or the memory device. (Configuration 11) 11. The exposure apparatus according to any one of configurations 1 to 10, wherein the light emitting means further comprises a driving means for controlling the light emission of each of the plurality of light emitting elements based on the image data received by the receiving means. (Configuration 12) 12. The exposure apparatus according to any one of configurations 1 to 11, wherein the plurality of light emitting elements included in the light emitting means and the receiving means are provided on the same substrate. (Configuration 13) an exposure device equipped with a light emitting means including a plurality of light emitting elements and a receiving means connected to a plurality of signal lines and configured to receive image data for controlling the light emission of the plurality of light emitting elements; a control means for determining the type of the exposure device and determining at least one signal line to be used for transmitting the image data from the plurality of signal lines to the receiving means based on the determined type of the exposure device; An image forming apparatus comprising: (Configuration 14) 15. The image forming apparatus according to configuration 14, wherein the control means determines the type of the exposure device based on information stored in a memory device of the exposure device or the potential of a control line connected to the exposure device. (Configuration 15) 15. The image forming apparatus according to claim 13, wherein the control unit notifies the receiving unit of determination information for determining the at least one signal line. (Configuration 16) 16. The image forming apparatus according to any one of configurations 13 to 15, wherein the control unit notifies the receiving unit of the determination information by storing the determination information in a storage unit of the light emitting unit. (Configuration 17) 17. The image forming apparatus according to claim 16, wherein the control means stores the determination information in the storage means of the light emitting means using a signal line different from the plurality of signal lines. (Configuration 18) 16. The image forming apparatus according to any one of configurations 13 to 15, wherein the control means notifies the receiving means of the determination information by transmitting the determination information to the receiving means via a first signal line among the plurality of signal lines. (Configuration 19) 19. The image forming apparatus according to claim 18, wherein the control means transmits the determination information to the receiving means via the first signal line, and then transmits the image data to the receiving means via the at least one signal line. (Configuration 20) 20. The image forming apparatus of claim 18, wherein the at least one signal line includes the first signal line.

[0050] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0051] 400: Light emitting chip, 1103: Image data storage unit

Claims

1. An exposure device mounted in an image forming apparatus, a light-emitting unit including a plurality of light-emitting elements, a plurality of connection parts arranged so as to be connectable to a plurality of signal lines, and a receiving unit that receives image data for controlling light emission of the plurality of light-emitting elements from the image forming apparatus; The exposure device, wherein the receiving means acquires determination information and determines the number of signal lines to be used for receiving the image data based on the acquired determination information.

2. 2. The exposure apparatus according to claim 1, wherein said receiving means acquires said determination information from said image forming apparatus.

3. the light emitting means further includes storage means for storing the determination information; 3. The exposure apparatus according to claim 2, wherein said receiving means acquires said determination information stored in said storage means by said image forming apparatus.

4. 4. The exposure apparatus according to claim 3, wherein the determination information is stored in the storage means by the image forming apparatus via a signal line different from the plurality of signal lines.

5. The exposure device according to claim 2, wherein the receiving means acquires the judgment information by receiving the judgment information from the image forming device via a first signal line among the plurality of signal lines connected to a first connection portion among the plurality of connection portions.

6. 6. The exposure apparatus according to claim 5, wherein said receiving means receives said determination information via said first signal line, and then receives said image data via a number of signal lines determined based on said determination information.

7. An exposure apparatus as described in Claim 6, wherein the number of signal lines determined based on the determination information includes the first signal line.

8. The exposure apparatus according to claim 5, wherein the light-emitting means is configured so that when a signal line is not connected to a second connection part among the plurality of connection parts that is different from the first connection part, the potential of the second connection part becomes a predetermined value.

9. An exposure device described in any one of claims 2 to 8, further comprising a circuit for causing the image forming device to determine the number of signal lines used by the receiving means to receive the image data, or a memory device for storing information for causing the image forming device to determine the number of signal lines used by the receiving means to receive the image data.

10. The image forming apparatus further comprises a circuit for causing the receiving means to determine the number of signal lines used to receive the image data, or a memory device for storing information for causing the image forming apparatus to determine the number of signal lines used to receive the image data, 2. The exposure apparatus according to claim 1, wherein said receiving means acquires said determination information based on said information stored in said circuit or said memory device.

11. 9. The exposure apparatus according to claim 1, wherein said light emitting means further comprises a driving means for controlling the light emission of each of said plurality of light emitting elements based on said image data received by said receiving means.

12. 9. The exposure apparatus according to claim 1, wherein the plurality of light emitting elements included in the light emitting means and the receiving means are provided on the same substrate.

13. an exposure device equipped with a light emitting means including a plurality of light emitting elements, a plurality of connection parts arranged so as to be connectable to a plurality of signal lines, and a receiving means for receiving image data for controlling the light emission of the plurality of light emitting elements; a control means for determining the type of the exposure device and determining the number of signal lines to be used for transmitting the image data to the receiving means based on the determined type of the exposure device; An image forming apparatus comprising:

14. 14. The image forming apparatus according to claim 13, wherein the control means determines the type of the exposure device based on information stored in a memory device of the exposure device or a potential of a control line connected to the exposure device.

15. 15. The image forming apparatus according to claim 13, wherein the control means notifies the receiving means of determination information for determining the number of signal lines used to transmit the image data.

16. 16. The image forming apparatus according to claim 15, wherein the control unit notifies the receiving unit of the determination information by storing the determination information in a storage unit of the light emitting unit.

17. 17. The image forming apparatus according to claim 16, wherein said control means stores said determination information in said storage means of said light emitting means using a signal line different from said plurality of signal lines.

18. 16. The image forming apparatus according to claim 15, wherein the control unit notifies the receiving unit of the determination information by transmitting the determination information to the receiving unit via a first signal line among the plurality of signal lines.

19. 19. The image forming apparatus according to claim 18, wherein the control unit transmits the determination information to the receiving unit via the first signal line, and then transmits the image data to the receiving unit via the determined number of signal lines.

20. The image forming apparatus according to claim 18 , wherein the determined number of signal lines includes the first signal line.

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