Image forming device

Abstract

To efficiently execute light exposure to a photoreceptor in one scan for line data of two or more scan lines in a case of performing interlace scan.SOLUTION: A memory controller (85) of an image formation apparatus writes line data of N scan lines adjacent to each other on a photoreceptor from a page memory (7) into a plurality of addresses adjacent to each other on a line memory (89), selects the address storing the line data of the N scan lines apart from each other by M scan lines on the photoreceptor from the line memory (89), and outputs the line data read out from the address to a laser emission part.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus. [Background technology]

[0002] Image forming devices that scan multiple beams in a single scan are known in the prior art. For example, the image forming device disclosed in Patent Document 1 stores image signals for multiple scan lines in a line buffer in one cycle of a horizontal synchronization signal in order to scan multiple beams in a single scan. The image forming device then outputs signals from the line buffer and scans multiple scan lines on a photosensitive element in a single scan. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-312041 Summary of the Invention [Problem to be solved by the invention]

[0004] The image forming apparatus described above scans adjacent scan lines with multiple beams, but is not designed to perform interlaced scanning, in which multiple beams are scanned at positions spaced apart by one or more scan lines. When interlaced scanning is performed in the image forming apparatus described above, the order of the data stored in the page memory that stores the raster image data does not match the order of the data used to expose the photosensitive member. Reading data from the page memory in accordance with the order of the exposure data would complicate memory access.

[0005] An object of the present disclosure is to efficiently expose a photosensitive member to line data for two or more scan lines in one scan when performing interlaced scanning. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, an image forming apparatus according to one aspect of the present invention includes a photosensitive member, N (N is a natural number of 2 or more) laser emitting units, an incident optical system that converts light emitted from the laser emitting units into beams, a deflector that deflects the beams from the incident optical system, a scanning optical system that focuses each of the N beams deflected by the deflector as a beam spot at a position on the photosensitive member that is separated by M (M is a natural number) scanning lines, an optical sensor that detects the beams deflected by the deflector, a page memory that stores raster image data, and a scanning optical system that scans the N beams read from the page memory and scans the image data on the photosensitive member. the memory controller writes the line data for N adjacent scan lines on the photosensitive body from the page memory to a plurality of adjacent addresses on the line memory for each period of the detection signal of the optical sensor, selects from the line memory an address at which the line data for N scan lines spaced apart from each other by M scan lines on the photosensitive body is stored, and outputs the line data read from the selected address to the laser emission unit.

[0007] When performing interlaced scanning, addresses are selected from line memories storing line data for N scan lines that are spaced apart by M scan lines. This allows the photosensitive element to be efficiently exposed to line data for N scan lines in one scan without reading out line data from line memory addresses that store line data that is not output to the laser emission unit.

[0008] The page memory may be a dynamic random access memory (DRAM), and the line memory may be a static random access memory (SRAM). By using an SRAM as the line memory, which has a faster storage processing speed than a DRAM, it is possible to complete the storage processing of line data by the line memory during one scan.

[0009] The image forming apparatus may include N output buffers corresponding to the N laser light emitting units, respectively, and the memory controller may write the line data corresponding to the N scan lines read from the selected addresses into the N output buffers. By writing the line data into the output buffers, exposure of the photosensitive member can be performed in synchronization with the detection signal of the optical sensor.

[0010] The image forming apparatus may further include a data processing circuit that converts the line data stored in a plurality of adjacent addresses on the line memory into line data for one scanning line, selected by the memory controller. Since the line data stored in a plurality of adjacent addresses on the line memory is converted into line data for one scanning line, the line data can be compressed.

[0011] The image forming apparatus may include a data processing circuit that selects at least one of the plurality of line data stored in a plurality of adjacent addresses on the line memory by the memory controller as data to be corrected, references the line data stored in an address adjacent to the address where the data to be corrected is stored on the line memory, and corrects the data to be corrected based on the referenced line data, thereby generating the line data for one scanning line.

[0012] The data to be corrected is corrected based on the line data stored in other adjacent addresses to generate line data for one scanning line, which makes it possible to make the line data for one scanning line into clearer pixel data.

[0013] The image forming apparatus may include an integrated circuit in which the line memory and the memory controller are provided, and the page memory may be provided outside the integrated circuit. By integrating the line memory and the memory controller into the integrated circuit, the time required to transfer information between the line memory and the memory controller can be reduced, thereby speeding up processing by the memory controller. [Effects of the Invention]

[0014] According to one aspect of the present invention, when performing interlaced scanning, it is possible to efficiently expose a photosensitive member to line data for two or more scanning lines in one scan. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a side cross-sectional view showing a configuration of an image forming apparatus according to a first embodiment of the present invention. [Figure 2] 2 is a cross-sectional view of a scanning optical device provided in the image forming apparatus shown in FIG. 1, viewed in the positive direction of the Y axis. [Figure 3] 3 is a view of the scanning optical device shown in FIG. 2 as viewed in the negative direction of the Z axis. [Figure 4] 4 is a diagram showing the configuration of a semiconductor laser included in the scanning optical device shown in FIG. 3. FIG. [Figure 5] 4 is a diagram illustrating interlaced scanning in the scanning optical device shown in FIG. 3. FIG. [Figure 6] 2 is a block diagram showing the configuration of an ASIC included in the image forming apparatus shown in FIG. 1. FIG. [Figure 7] 7 is a diagram illustrating processing by a memory controller included in the ASIC illustrated in FIG. 6. [Figure 8]FIG. 10 is a diagram illustrating processing by a memory controller included in an image forming apparatus according to a second embodiment of the present invention. [Figure 9] FIG. 10 is a diagram illustrating processing by a memory controller included in an image forming apparatus according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] [Embodiment 1] <Configuration of Image Forming Apparatus 1> 1 is a side cross-sectional view showing the configuration of an image forming apparatus 1 according to Embodiment 1 of the present invention. In Fig. 1, the direction in which a plurality of process units 42 are arranged is the X-axis direction, the direction from the paper feed unit 3 toward the image forming unit 4 is the positive Z-axis direction, and the direction perpendicular to both the X-axis direction and the Z-axis direction is the Y-axis direction.

[0017] The image forming apparatus 1 is, for example, a horizontally-mounted tandem color laser printer in which multiple process units 42 are arranged in parallel along the X-axis direction. The image forming apparatus 1 scans multiple beams on adjacent scan lines on the photosensitive element 51, performing interlaced scanning in which the multiple beams are scanned at positions spaced apart by one or more scan lines. The scan lines are aligned in the sub-scanning direction, which is the same direction as the conveyance direction of the sheet S1. As shown in FIG. 1, the image forming apparatus 1 includes a main casing 2, a paper feed unit 3, an image forming unit 4, and a paper discharge unit 5.

[0018] The main body casing 2 houses a paper feed unit 3, an image forming unit 4, and a paper discharge unit 5. The paper feed unit 3 feeds sheets S1 and includes a sheet cassette 31, paper feed rollers 32, a transport roller 33, a paper feed path 34, and registration rollers 35. The sheet cassette 31 is located at the bottom of the main body casing 2, and sheets S1 are stacked in the sheet cassette 31.

[0019] The paper feed rollers 32 are provided above the sheet cassette 31 and transport the sheet S1 stacked in the sheet cassette 31 to the transport rollers 33. The transport rollers 33 transport the sheet S1 transported by the paper feed rollers 32 to a paper feed path 34. The upstream end of the paper feed path 34 is adjacent to the transport rollers 33, and the downstream end of the paper feed path 34 is adjacent to the registration rollers 35. The paper feed path 34 forms a transport path along which the sheet S1 is transported from the transport rollers 33 to the registration rollers 35.

[0020] The image forming unit 4 forms an image on the sheet S1 fed by the paper feed unit 3, and includes a scanning optical device 41, a process unit 42, a transfer unit 43, and a fixing unit 44. Details of the image forming unit 4 will be described later.

[0021] <Configuration of the scanning optical device 41> The scanning optical device 41 is disposed above a plurality of process units 42 in the upper part of the main body casing 2. Fig. 2 is a cross-sectional view of the scanning optical device 41 provided in the image forming apparatus 1 shown in Fig. 1 as viewed in the positive direction of the Y axis, and Fig. 3 is a view of the scanning optical device 41 shown in Fig. 2 as viewed in the negative direction of the Z axis. Fig. 4 is a diagram showing the configuration of a semiconductor laser 412M provided in the scanning optical device 41 shown in Fig. 3.

[0022] 2 and 3, the scanning optical device 41 includes a frame 411, semiconductor lasers 412M, 412K, 412Y, and 412C, an incident optical system 413, a polygon mirror 414 as an example of a deflector, a scanning optical system 415, and a BD (Beam Detect) sensor 8 as an example of an optical sensor. Each of the semiconductor lasers 412M, 412K, 412Y, and 412C includes N (N is a natural number of 2 or more) laser light emitting units. For example, as shown in FIG. 4, the semiconductor laser 412M includes N laser light emitting units E1 and E2, where N=2.

[0023] The frame 411 is box-shaped and made of resin, with an opening on the positive side of the Z axis. The frame 411 holds a polygon mirror 414, semiconductor lasers 412M, 412K, 412Y, and 412C, an incident optical system 413, and a scanning optical system 415. Exit windows WL2 corresponding to each color are formed in a bottom wall WL1 of the frame 411. The multiple exit windows WL2 are formed at intervals in the X axis direction. The frame 411 includes the bottom wall WL1 and side walls WL3 extending in the positive direction of the Z axis from the four peripheries of the bottom wall WL1.

[0024] The polygon mirror 414 is disposed approximately in the center of the frame 411 and is mounted on a motor substrate 414B. The polygon mirror 414 deflects the beam from the incident optical system 413. Details of the incident optical system 413 will be described later. The polygon mirror 414 is formed in a polyhedron having a plurality of beam deflection surfaces 414S. The polygon mirror 414 is driven to rotate at high speed around a rotation axis 414A provided at the center of the polygon mirror 414 by the power of a scanner motor provided on the motor substrate 414B.

[0025] The semiconductor lasers 412M and 412K are arranged side by side in the X-axis direction. The semiconductor lasers 412C and 412Y are arranged facing each other in the X-axis direction. The light emitted from the semiconductor laser 412M is approximately perpendicular to the light emitted from the semiconductor laser 412Y, and the light emitted from the semiconductor laser 412K is approximately perpendicular to the light emitted from the semiconductor laser 412C.

[0026] The incident optical system 413 includes four coupling lenses 413L, four slit plates 413S, two reflecting mirrors 413M, and two cylindrical lenses 413Z. The four coupling lenses 413L convert the light emitted from the laser emission units of the semiconductor lasers 412M, 412K, 412Y, and 412C into beams.

[0027] The slit plate 413S is disposed so as to face each of the four coupling lenses 413L. The beams from the coupling lenses 413L have apertures defined by the slits of the slit plate 413S.

[0028] One of the two reflecting mirrors 413M is provided so as to be inclined at approximately 45° with respect to the respective flat plates of the approximately L-shaped slit plate 413S arranged opposite the semiconductor laser 412Y. One of the reflecting mirrors 413M is formed so as to reflect the light emitted from the semiconductor laser 412Y at approximately 90°. One of the reflecting mirrors 413M is arranged at a position shifted in the Z-axis direction from the light emitted from the semiconductor laser 412M, and the light emitted from the semiconductor laser 412M is not reflected by one of the reflecting mirrors 413M.

[0029] The other of the two reflecting mirrors 413M is provided so as to be inclined at approximately 45° with respect to the respective flat plates of the approximately L-shaped slit plate 413S arranged opposite the semiconductor laser 412C. The other reflecting mirror 413M is formed so as to reflect the light emitted from the semiconductor laser 412C at approximately 90°. The other reflecting mirror 413M is arranged at a position shifted in the Z-axis direction from the light emitted from the semiconductor laser 412K, and the light emitted from the semiconductor laser 412K is not reflected by the other reflecting mirror 413M.

[0030] The cylindrical lens 413Z is a resin lens formed by injection molding using a resin material, and is arranged to face the slit plate 413S at a predetermined distance. The surface of the cylindrical lens 413Z facing the slit plate 413S is a cylindrical incident surface onto which the beam that has passed through the slit plate 413S is incident.

[0031] The surface of the cylindrical lens 413Z facing the polygon mirror 414 is a flat exit surface that emits the beam incident from the entrance surface. The polygon mirror 414 rotates at high speed to deflect the beam that has passed through the cylindrical lens 413Z.

[0032] The scanning optical system 415 focuses the N beams deflected by the polygon mirror 414 as beam spots at positions spaced apart by M scanning lines (M is a natural number) on the photosensitive member 51. The N beams are formed by converting light emitted from N laser emission units E1 and E2 of the semiconductor laser 412M into beams by the coupling lens 413L and deflecting them by the polygon mirror 414.

[0033] 5 is a diagram for explaining interlaced scanning in the scanning optical device 41 shown in FIG. 3, and shows the movements of images IE1 and IE2 of the laser emission units E1 and E2 on the scanned surface of the photosensitive member 51. In FIG. 5, N scanning lines spaced apart from each other by M scanning lines in the sub-scanning direction are exposed by the light emitted from the laser emission units E1 and E2, where N=2 and M=3.

[0034] For example, scan lines S11 and S14 are separated from each other by M scan lines in the sub-scanning direction. Here, M represents the number of intervals between the scan lines. Therefore, for example, when counting the number of scan lines from scan line S11 as the starting point to scan line S14, M represents the number of scan lines S12 to S14 excluding the starting scan line S11.

[0035] Furthermore, for example, at a predetermined timing, the image IE1 of the laser emission unit E1 and the image IE2 of the laser emission unit E2 are scanned in the main scanning direction along the scanning line S11 and the scanning line S14, respectively. The center-to-center distance in the sub-scanning direction between the images IE1 and IE2 corresponds to the pitch P of the beam group irradiated from the semiconductor laser 412M, and is three times the center-to-center distance Pi between adjacent scanning lines S11, S12, S13, etc.

[0036] Meanwhile, the photosensitive element 51 is rotated by a motor (not shown). The scanned surface of the photosensitive element 51, on which the beam group is scanned, moves a distance Pm in the sub-scanning direction while the images IE1 and IE2 are scanned once in the main-scanning direction. This distance Pm is twice the distance Pi. Therefore, for example, after the images IE1 and IE2 scan the scan lines S11 and S14, the images IE1 and IE2 scan the scan lines S13 and S16, which are shifted by two lines, as shown by the two-dot chain lines. Then, at the next timing, the images IE1 and IE2 scan the scan lines S15 and S18, which are shifted by another two lines. Thereafter, the same scanning pattern is repeated.

[0037] In this embodiment, as described above, scanning is performed between the kth (k is a natural number) scanning line Sk and the k+3th scanning line Sk+3 in the sub-scanning direction for each scanning by the beam group, thereby sequentially exposing the scanned surface of the photosensitive element 51 along all the scanning lines.

[0038] The N beams of light emitted from each of the other semiconductor lasers 412K, 412Y, and 412C are similar to the N beams of light emitted from the N laser emission units E1 and E2 of the semiconductor laser 412M. As shown in Fig. 2, the scanning optical system 415 is made up of scanning optical systems 415M, 415K, 415Y, and 415C.

[0039] In the scanning optical system 415Y corresponding to yellow, light emitted from a semiconductor laser 412Y is converted by a coupling lens 413L and the beam deflected by a polygon mirror 414 is focused on the photosensitive element 51. The scanning optical system 415Y includes a scanning lens 11, a mirror 12 that reflects the beam that has passed above the scanning lens 11, and a mirror 13 that reflects the beam reflected by the mirror 12 toward the photosensitive element 51.

[0040] In the scanning optical system 415Y, the beam passes above the scanning lens 11, is reflected obliquely upward by the mirror 12, is reflected in the negative direction of the Z axis by the mirror 13, and is emitted from the exit window WL2.

[0041] In the scanning optical system 415M corresponding to magenta, light emitted from a semiconductor laser 412M is converted by a coupling lens 413L and deflected by a polygon mirror 414, and the resulting beam is focused on the photosensitive element 51. The scanning optical system 415M is disposed between the polygon mirror 414 and the scanning optical system 415Y, and includes two mirrors 14 and 15 that reflect the beam that has passed through the lower side of the scanning lens 11, and a mirror 16 that reflects the beam reflected by the mirror 15 toward the photosensitive element 51.

[0042] In the scanning optical system 415M, the beam passes below the scanning lens 11, is reflected upward by mirror 14, is reflected in the positive direction of the X axis by mirror 15, is reflected in the negative direction of the Z axis by mirror 16, and is emitted from the exit window WL2.

[0043] 2, scanning optical system 415 is symmetrical with respect to polygon mirror 414. Therefore, the configuration of scanning optical system 415C corresponding to cyan is similar to the configuration of scanning optical system 415M, and the configuration of scanning optical system 415K corresponding to black is similar to the configuration of scanning optical system 415Y.

[0044] <Configuration of the process unit 42> As shown in Fig. 1, a plurality of process units 42 are provided corresponding to the plurality of colors of toner. That is, the process units 42 consist of four: a yellow process unit 42Y, a magenta process unit 42M, a cyan process unit 42C, and a black process unit 42K. These process units 42 are arranged in parallel at intervals in the X-axis direction. Each process unit 42 includes a photoconductor 51, a charger 52, and a developer cartridge 53.

[0045] The photoreceptor 51 has a cylindrical shape, and its outermost layer is formed of a positively charged photosensitive layer made of polycarbonate or the like. The charger 52 is a positively charged scorotron charger that includes a wire and a grid and generates a corona discharge by applying a charging bias, and is disposed opposite the photoreceptor 51 on the positive side of the X axis, with a gap between them so as not to come into contact with the photoreceptor 51.

[0046] The developing cartridge 53 includes a developing roller 56, a supply roller 57, and a layer thickness regulating blade 58. The upper portion of the housing of the developing cartridge 53 is formed as a toner storage chamber 55 for storing toner, and toner of each color is stored therein.

[0047] In each process unit 42, during image formation, toner of each color contained in each toner storage chamber 55 is supplied to a supply roller 57, and is supplied to a developing roller 56 by the rotation of the supply roller 57. At this time, the toner is positively frictionally charged between the supply roller 57 and the developing roller 56 to which a developing bias is applied. As the developing roller 56 rotates, the toner supplied onto the developing roller 56 enters between a layer thickness regulating blade 58 and the developing roller 56, and is carried on the developing roller 56 as a thin layer of a uniform thickness.

[0048] Meanwhile, the charger 52 generates a corona discharge by applying a charging bias, thereby uniformly positively charging the surface of the photoreceptor 51. After the surface of the photoreceptor 51 is uniformly positively charged by the charger 52 as the photoreceptor 51 rotates, the surface is exposed to light corresponding to line data (described later) by scanning with a beam emitted from the exit window WL2 of the scanning optical device 41, and electrostatic latent images of each color corresponding to the image to be formed on the sheet S1 are formed.

[0049] Further, when the photoreceptor 51 rotates, the toner carried on the surface of the developing roller 56 and positively charged contacts the photoreceptor 51 in opposition due to the rotation of the developing roller 56. At this time, the toner is supplied to the exposed portion of the surface of the photoreceptor 51 that is uniformly positively charged and has been exposed by the beam and has a lowered potential. As a result, the electrostatic latent image on the photoreceptor 51 is visualized, and a toner image by reversal development is carried on the surface of the photoreceptor 51 corresponding to each color.

[0050] The transfer unit 43 is disposed along the X-axis direction above the sheet cassette 31 and below the process unit 42 within the main body casing 2. The transfer unit 43 includes a drive roller 59, a driven roller 60, a conveyance belt 61, and a transfer roller 62. The conveyance belt 61 is an endless belt member wound around the drive roller 59 and the driven roller 60. The driven roller 60 rotates as the drive roller 59 rotates. The transfer roller 62 transfers toner to the sheet S1 conveyed on the conveyance belt 61.

[0051] The fixing unit 44 fixes the toner to the sheet S1 to which the toner has been transferred by the transfer unit 43. The paper discharge unit 5 includes a conveyance roller 70, a paper discharge path 71, a paper discharge roller 72, and a paper discharge tray 73. The conveyance roller 70 conveys the sheet S1 to which the toner has been fixed by the fixing unit 44 to the paper discharge path 71.

[0052] The upstream end of the paper discharge path 71 is adjacent to the conveyance roller 70, and the downstream end of the paper discharge path 71 is adjacent to the paper discharge roller 72. The paper discharge path 71 forms a conveyance path through which the sheet S1 is conveyed from the conveyance roller 70 to the paper discharge roller 72. The paper discharge roller 72 discharges the sheet S1 to the paper discharge tray 73. The paper discharge tray 73 is formed as an inclined surface on the upper surface of the main body casing 2 that slopes downward in the positive direction of the X-axis.

[0053] <Configuration of ASIC6> Fig. 6 is a block diagram showing the configuration of the ASIC 6 included in the image forming apparatus 1 shown in Fig. 1. As shown in Fig. 6, the image forming apparatus 1 includes the ASIC 6 as an example of an integrated circuit, and a page memory 7. The ASIC 6 includes a storage control circuit 81, a storage circuit 82, a CPU (Central Processing Unit) 83, N output buffers 84, and an internal bus B1. In other words, the ASIC 6 is provided with the storage control circuit 81, the storage circuit 82, the CPU 83, N output buffers 84, and the internal bus B1.

[0054] The following description focuses on the semiconductor laser 412M among the semiconductor lasers 412M, 412K, 412Y, and 412C. The description of the semiconductor laser 412M also applies to the other semiconductor lasers 412K, 412Y, and 412C.

[0055] The page memory 7 stores raster image data generated by the image forming apparatus 1 from print data received by the image forming apparatus 1 from an external device. The page memory 7 is provided outside the ASIC 6. The storage control circuit 81 reads the raster image data from the page memory 7 and outputs the read raster image data to a DMA (Direct Memory Access) controller 86 via an internal bus B1. The internal bus B1 is connected to the storage control circuit 81, the CPU 83, and the DMA controller 86.

[0056] The memory circuit 82 includes a memory controller 85, a line memory 89, and a data processing circuit 90. In other words, the memory circuit 82 is provided with the memory controller 85, the line memory 89, and the data processing circuit 90. By integrating the line memory 89 and the memory controller 85 into the ASIC 6, it is possible to reduce the time required for information to move between the line memory 89 and the memory controller 85. Therefore, it is possible to speed up processing by the memory controller 85.

[0057] The memory controller 85 includes a DMA controller 86, a write circuit 87, and a read circuit 88. The DMA controller 86 transfers the raster image data output from the storage control circuit 81 to the write circuit 87. The write circuit 87 generates line data, which is data for pixels corresponding to scan lines on the photosensitive element 51, from the raster image data transferred from the DMA controller 86, and writes the generated line data to a line memory 89. The line memory 89 stores the line data.

[0058] The read circuit 88 reads out line data from the line memory 89 and outputs the read line data to a data processing circuit 90. The data processing circuit 90 stores the line data output from the read circuit 88 in N output buffers 84. The read circuit 88 also outputs the line data to the N laser emission units E1, E2 of the semiconductor laser 412M via the data processing circuit 90 and the N output buffers 84. The N output buffers 84 correspond to the N laser emission units E1, E2 of the semiconductor laser 412M, respectively. The output buffer 84 is, for example, a FIFO (First In First Out) memory.

[0059] It is preferable that the page memory 7 is a DRAM (Dynamic Random Access Memory), and the line memory 89 is an SRAM (Static Random Access Memory). By using an SRAM, which has a faster storage process speed than a DRAM, as the line memory 89, it is possible to complete the storage process of line data by the line memory 89 during one scan.

[0060] 3, the BD sensor 8 is disposed at a position where the beam reflected by the beam deflection surface 414S is incident when the angle of the beam deflection surface 414S with respect to the beam irradiation direction is a specific angle before exposure based on line data. The BD sensor 8 detects the beam deflected by the polygon mirror 414. The BD sensor 8 outputs a detection signal to the DMA controller 86 that goes low when no beam is incident and goes high when the beam is incident. The DMA controller 86 transfers the detection signal output from the BD sensor 8 to the write circuit 87.

[0061] <Processing of memory controller 85> Fig. 7 is a diagram showing the processing of the memory controller 85 provided in the ASIC 6 shown in Fig. 6. In Fig. 7, A1 to A12 on the left side indicate addresses in the line memory 89, and indicate processing for one scan every two columns to the right. The line memory 89 includes addresses A1 to A12. The memory controller 85 processes the address next to address A12 in the line memory 89 as address A1.

[0062] 7, the processing of the memory controller 85 will be described assuming N=2 and M=3. N is the number of laser emission units E1 and E2 of the semiconductor laser 412M, and M is the number of spaced apart scan lines on the photosensitive member 51. The line data stored in addresses A1 to A10 is line data for 10 adjacent scan lines on the photosensitive member 51. Furthermore, before the image forming apparatus 1 performs printing processing on the sheet S1, the write circuit 87 initializes the line memory 89, that is, makes all the line data in the line memory 89 blank.

[0063] The memory controller 85 executes the process for one scan, which will be described below, for each period of the detection signal from the BD sensor 8. That is, when the write circuit 87 recognizes that the detection signal from the BD sensor 8 is at a high level, the process for one scan, which will be described below, begins.

[0064] 7, in the first scan, the write circuit 87 executes a process W1 in which it writes line data for N adjacent scan lines on the photosensitive member 51 from the page memory 7 to N adjacent addresses A3 and A4 on the line memory 89. The read circuit 88 also selects addresses A11 and A2 from the line memory 89 in which line data for N scan lines spaced apart from each other by M scan lines on the photosensitive member 51 are stored.

[0065] Then, the read circuit 88 executes a process R1 in which it outputs the line data read from the selected addresses A11 and A2 to the N laser emission units E1 and E2 of the semiconductor laser 412M. The addresses A11 and A2 are separated by M lines from each other on the line memory 89, starting from address A11. Address A2 stores line data written by the write circuit 87 in a scan prior to the first scan, and address A11 stores blank data. Therefore, the line on the photosensitive element 51 corresponding to address A2 is scanned by the scanning optical device 41, and the line on the photosensitive element 51 corresponding to address A11 is not scanned by the scanning optical device 41.

[0066] Furthermore, in process R1, the readout circuit 88 writes line data corresponding to each of the N scanning lines read out from the selected addresses A11, A2 into the N output buffers 84 via the data processing circuit 90. The scanning optical device 41 reads the line data from the N output buffers 84 and outputs the line data to the N laser emission units E1, E2 of the semiconductor laser 412M. By the readout circuit 88 writing the line data into the output buffers 84, the scanning optical device 41 can perform exposure of the photosensitive element 51 in synchronization with the detection signal of the BD sensor 8.

[0067] After the first scan starts, the detection signal of the BD sensor 8 goes low, and when the detection signal of the BD sensor 8 goes high again, the processing of the second scan starts. During the second scan, the write circuit 87 executes process W2 to write line data for N adjacent scan lines on the photosensitive member 51 from the page memory 7 to N adjacent addresses A5 and A6 in the line memory 89. The write circuit 87 selects addresses A5 and A6 as the N addresses next chronologically adjacent to addresses A3 and A4 for which process W1 was executed during the first scan.

[0068] Furthermore, the read circuit 88 selects from the line memory 89 addresses A1 and A4 storing line data for N scanning lines spaced apart by M scanning lines on the photosensitive element 51. The write circuit 87 selects address A1, which is the chronologically later address, from among addresses A12 and A1 located between addresses A11 and A2 selected in the first scan, and selects address A4, which is spaced apart by M lines from address A1.

[0069] Then, the read circuit 88 executes process R2 to output the line data read from the selected addresses A1 and A4 to the N laser emission units E1 and E2 of the semiconductor laser 412M. Address A1 stores line data written by the write circuit 87 in a scan prior to the first scan, and address A4 stores line data written by the write circuit 87 in process W1 of the first scan. Therefore, the scanning optical device 41 scans the line on the photosensitive element 51 corresponding to address A1, and the scanning optical device 41 scans the line on the photosensitive element 51 corresponding to address A4.

[0070] In the third and subsequent scans, similar to the first and second scans, the write circuit 87 executes processes W3 to W6, and the read circuit 88 executes processes R3 to R6. As a result, processes R1 to R6 cause the scanning optical device 41 to scan 10 adjacent lines on the photosensitive member 51 corresponding to addresses A1 to A10.

[0071] In addition, the data processing circuit 90 sets the line data read from address A12 by the read circuit 88 to zero in process R6 so that the line on the photosensitive member 51 corresponding to address A12 is not scanned by the optical scanning device 41. Addresses A11 and A12 are addresses that are not to be scanned by the optical scanning device 41.

[0072] As described above, when the image forming apparatus 1 performs interlaced scanning, an address is selected from the line memory 89 in which line data for N scan lines that are spaced apart by M scan lines is stored. Therefore, the photosensitive member 51 can be efficiently exposed to line data for N scan lines in one scan without reading line data from addresses in the line memory 89 in which line data that is not to be output to the laser emission units E1, E2 is stored. In other words, the access time to the page memory 7 can be shortened compared to when line data is read from the line memory 89 until the required data is obtained and unnecessary data from the read line data is discarded.

[0073] [Embodiment 2] A second embodiment of the present invention will be described below. Fig. 8 is a diagram showing the processing of a memory controller 85 provided in an image forming apparatus 1 according to the second embodiment of the present invention. The second embodiment differs from the first embodiment in the processing content executed by the memory controller 85 and the data processing circuit 90.

[0074] 8, A1 to A16 on the left side indicate addresses in the line memory 89, and indicate processing for one scan every two columns to the right. The line memory 89 includes addresses A1 to A16. The memory controller 85 processes the address next to address A16 in the line memory 89 as address A1.

[0075] 8, the processing of the memory controller 85 will be described assuming N=2 and M=3. The line data stored in addresses A1 to A12 is line data for six adjacent scan lines on the photosensitive element 51. In other words, one scan line on the photosensitive element 51 corresponds to two addresses in the line memory 89.

[0076] 8, during the first scan, the write circuit 87 executes a process W1 in which it writes line data for N adjacent scan lines on the photosensitive member 51 from the page memory 7 to 2N adjacent addresses A5 to A8 on the line memory 89. The addresses A5 and A6 correspond to one of the N scan lines on the photosensitive member 51, and the addresses A7 and A8 correspond to the other of the N scan lines on the photosensitive member 51.

[0077] Furthermore, the readout circuit 88 selects addresses A13, A14, A3, and A4 in which line data for N scanning lines spaced apart by M scanning lines on the photosensitive element 51 is stored from the line memory 89. Then, the readout circuit 88 executes a process R1 in which the line data read out from the selected addresses A13, A14, A3, and A4 is output to the N laser light-emitting units E1 and E2 of the semiconductor laser 412M.

[0078] That is, the read circuit 88 outputs the line data read from addresses A13 and A14 to the laser emission unit E1 of the semiconductor laser 412M, and outputs the line data read from addresses A3 and A4 to the laser emission unit E2 of the semiconductor laser 412M.

[0079] More specifically, the read circuit 88 outputs the line data read from addresses A13 and A14 to the data processing circuit 90. The data processing circuit 90 converts the line data at addresses A13 and A14 output from the read circuit 88 into line data for one scanning line. In other words, the data processing circuit 90 converts multiple line data selected by the read circuit 88 and stored in multiple adjacent addresses on the line memory 89 into line data for one scanning line. The data processing circuit 90 outputs the converted line data to the laser emission unit E1 of the semiconductor laser 412M.

[0080] Furthermore, the readout circuit 88 outputs the line data read out from addresses A3 and A4 to the data processing circuit 90. The data processing circuit 90 converts the line data at addresses A3 and A4 output from the readout circuit 88 into line data for one scanning line. The data processing circuit 90 outputs the converted line data to the laser emission unit E2 of the semiconductor laser 412M.

[0081] Addresses A13 and A3 are spaced apart from each other on line memory 89 by 2M addresses, which correspond to M adjacent scan lines on photoconductor 51, starting from address A13. Addresses A3 and A4 store line data written by write circuit 87 in a scan prior to the first scan, and addresses A13 and A14 store blank data. Therefore, the lines on photoconductor 51 corresponding to addresses A3 and A4 are scanned by optical scanning device 41, but the lines on photoconductor 51 corresponding to addresses A13 and A14 are not scanned by optical scanning device 41.

[0082] After the first scan starts, the detection signal of the BD sensor 8 goes low, and when the detection signal of the BD sensor 8 goes high again, the processing of the second scan starts. During the second scan, the write circuit 87 executes process W2 to write line data for N adjacent scan lines on the photosensitive member 51 from the page memory 7 to 2N adjacent addresses A9 to A12 in the line memory 89. The write circuit 87 selects addresses A9 to A12 as the 2N addresses next in time series to addresses A5 to A8 for which process W1 was executed during the first scan.

[0083] The readout circuit 88 also selects addresses A1, A2, A7, and A8 from the line memory 89, which store line data for N scanning lines spaced apart by M scanning lines on the photosensitive element 51. The readout circuit 88 then executes process R2, which outputs the line data read out from the selected addresses A1, A2, A7, and A8 to the N laser emission units E1 and E2 of the semiconductor laser 412M.

[0084] More specifically, the read circuit 88 outputs the line data read from addresses A1 and A2 to the data processing circuit 90. The data processing circuit 90 converts the line data at addresses A1 and A2 output from the read circuit 88 into line data for one scanning line. The read circuit 88 also outputs the line data read from addresses A7 and A8 to the data processing circuit 90. The data processing circuit 90 converts the line data at addresses A7 and A8 output from the read circuit 88 into line data for one scanning line.

[0085] Addresses A1 and A2 store line data written by the writing circuit 87 in a scan prior to the first scan, and addresses A7 and A8 store line data written by the writing circuit 87 in process W1 of the first scan. Therefore, scanning by the scanning optical device 41 is performed on the lines on the photosensitive member 51 corresponding to addresses A1, A2, A7, and A8.

[0086] In the third and subsequent scans, similar to the first and second scans, the write circuit 87 executes processes W3 and W4, and the read circuit 88 executes processes R3 and R4. As a result, processes R1 to R4 cause the scanning optical device 41 to scan six adjacent scan lines on the photosensitive element 51 corresponding to addresses A1 to A12.

[0087] In order to prevent the scanning optical device 41 from scanning the lines on the photosensitive member 51 corresponding to the addresses A15 and A16, the data processing circuit 90 sets the line data read from the addresses A15 and A16 by the read circuit 88 to zero in process R4. The addresses A13 to A16 are addresses that are not to be scanned by the scanning optical device 41.

[0088] As described above, the data processing circuit 90 performs the following processing by converting multiple line data into line data for one scanning line. Specifically, consider a case where raster image data of 1200 x 1200 dpi (resolution in the main scanning direction x resolution in the sub-scanning direction, the same applies below) is stored in the page memory 7. In this case, the data processing circuit 90 converts the 1200 x 1200 dpi data into data of 2400 x 600 dpi or 4800 x 600 dpi. This makes it possible to expose data corresponding to 1200 x 1200 dpi even when the exposure resolution of the scanning optical device 41 is 600 dpi in the sub-scanning direction.

[0089] As a result, in the image forming apparatus 1 of embodiment 2, multiple line data stored in multiple adjacent addresses on the line memory 89 are converted into line data for one scanning line, thereby compressing the line data.

[0090] [Embodiment 3] A third embodiment of the present invention will be described below. Fig. 9 is a diagram showing the processing of a memory controller 85 provided in an image forming apparatus 1 according to the third embodiment of the present invention. The third embodiment differs from the first and second embodiments in the processing content executed by the memory controller 85 and the data processing circuit 90.

[0091] In FIG. 9, A1 to A11 on the left side indicate addresses in the line memory 89, and indicate processing for one scan every two columns to the right. The line memory 89 includes addresses A1 to A11. The memory controller 85 processes the address next to address A11 in the line memory 89 as address A1. Also, in FIG. 9, the processing of the memory controller 85 will be described assuming N=2 and M=3. The line data stored in addresses A1 to A10 becomes line data for 10 adjacent scan lines on the photosensitive element 51.

[0092] 9, during the first scan, the write circuit 87 executes a process W1 in which it writes line data for N adjacent scan lines on the photosensitive element 51 from the page memory 7 to N adjacent addresses A1 and A2 on the line memory 89. The read circuit 88 also selects addresses A5 to A10 from the line memory 89 in which line data for N scan lines spaced apart by M scan lines on the photosensitive element 51 are stored. The read circuit 88 then executes a process R1 in which it outputs the line data read from the selected addresses A5 to A10 to N laser emission units E1 and E2 of the semiconductor laser 412M.

[0093] Specifically, the read circuit 88 outputs the line data read from the selected addresses A5 to A10 to the data processing circuit 90. The data processing circuit 90 sets the line data at address A6 out of the line data at addresses A5 to A7 output from the read circuit 88 as data to be corrected.

[0094] The data processing circuit 90 references the line data stored at addresses A5 and A7 adjacent to the line data stored at address A6, which is the data to be corrected, in the line memory 89. The data processing circuit 90 generates line data for one scanning line by correcting the line data at address A6, which is the data to be corrected, based on the line data at addresses A5 and A7, which are the reference data. The data processing circuit 90 outputs the generated line data to the laser emission unit E1 of the semiconductor laser 412M.

[0095] Furthermore, the data processing circuit 90 sets the line data at address A9 as the data to be corrected out of the line data at addresses A8 to A10 output from the read circuit 88. The data processing circuit 90 refers to the line data stored at addresses A8 and A10 adjacent to the line data stored at address A9 on the line memory 89 as the data to be corrected.

[0096] The data processing circuit 90 generates line data for one scanning line by correcting the line data at address A9, which is the data to be corrected, based on the line data at addresses A8 and A10, which are reference data. The data processing circuit 90 outputs the generated line data to the laser emission unit E2 of the semiconductor laser 412M. Here, addresses A6 and A9, which are the targets of the data to be corrected, are separated from each other by M lines on the line memory 89.

[0097] After the first scan starts, the detection signal of the BD sensor 8 goes low, and when the detection signal of the BD sensor 8 goes high again, the processing of the second scan starts. During the second scan, the write circuit 87 executes process W2 to write line data for N adjacent scan lines on the photosensitive member 51 from the page memory 7 to N adjacent addresses A3 and A4 in the line memory 89. The write circuit 87 selects addresses A3 and A4 as the N addresses next in time series to addresses A1 and A2 for which process W1 was executed during the first scan.

[0098] The read circuit 88 also selects addresses A7 to A11, A1 from the line memory 89, which store line data for N scanning lines spaced apart by M scanning lines on the photosensitive element 51. The write circuit 87 selects address A8 as data to be corrected. The write circuit 87 also selects addresses A7 and A9 adjacent to address A8 as reference data.

[0099] Furthermore, the write circuit 87 selects address A11 as the data to be corrected and selects addresses A10 and A1 as the reference data. Then, the read circuit 88 executes process R2 to output the line data read from the selected addresses A7 to A11 and A1 to the N laser emission units E1 and E2 of the semiconductor laser 412M.

[0100] Specifically, the read circuit 88 outputs the line data read from the selected addresses A7 to A11, A1 to the data processing circuit 90. The data processing circuit 90 sets the line data at address A8 out of the line data at addresses A7 to A9 output from the read circuit 88 as data to be corrected. Furthermore, the data processing circuit 90 sets the line data at address A11 out of the line data at addresses A10, A11, A1 output from the read circuit 88 as data to be corrected.

[0101] In the third and subsequent scans, as in the first and second scans, the write circuit 87 executes processes W3 to W8, and the read circuit 88 executes processes R3 to R8. As a result, processes R1 to R8 cause the optical scanning device 41 to scan 10 adjacent scan lines on the photosensitive element 51 corresponding to addresses A1 to A10. Note that the data processing circuit 90 sets the line data read from addresses A11, A1, and A2 by the read circuit 88 in process R8 to zero so that the optical scanning device 41 does not scan the lines on the photosensitive element 51 corresponding to addresses A11, A1, and A2.

[0102] As described above, the data processing circuit 90 selects as correction target data at least one of the multiple line data items selected by the memory controller 85 and stored in multiple adjacent addresses on the line memory 89. The data processing circuit 90 also references line data stored in an address adjacent to the address where the correction target data item is stored on the line memory 89. Furthermore, the data processing circuit 90 generates line data for one scanning line by correcting the correction target data item based on the referenced line data.

[0103] In this way, the data to be corrected is corrected based on the line data stored in other adjacent addresses, thereby generating line data for one scanning line, which can be made into clearer pixel data.

[0104] [Software implementation example] The functions of image forming apparatus 1 can be realized by a program that causes a computer to function as image forming apparatus 1, and a program that causes a computer to function as each control block of image forming apparatus 1 (particularly each part included in ASIC 6).

[0105] In this case, the image forming apparatus 1 includes a computer having at least one control device (e.g., a processor) and at least one storage device (e.g., a memory) as hardware for executing the program. The control device and storage device execute the program, thereby realizing the functions described in each of the above embodiments.

[0106] The above program may be recorded non-transitoryly on one or more computer-readable recording media. The image forming apparatus 1 may or may not include the recording media. In the latter case, the program may be supplied to the image forming apparatus 1 via any wired or wireless transmission medium. Alternatively, the functions of the above control blocks may be realized by, for example, a quantum computer.

[0107] Furthermore, each process described in each of the above embodiments may be executed by AI (Artificial Intelligence). In this case, the AI ​​may run on the control device or on another device (for example, an edge computer or a cloud server).

[0108] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0109] 1. Image forming device 6 ASIC 7 page memory 8 BD sensor 51 Photoreceptor 84 output buffers 85 Memory Controller 89 Line Memory 90 Data Processing Circuit E1, E2 laser emission unit 413 Injection optical system 414 Polygon Mirror 415 Scanning Optical System

Claims

1. A photoreceptor; N laser light emitting units (N is a natural number of 2 or more); an incident optical system that converts light emitted from the laser light emitting unit into a beam; a deflector for deflecting the beam from the incident optical system; a scanning optical system that focuses the N beams deflected by the deflector as beam spots at positions on the photosensitive member that are spaced apart by M scanning lines (M is a natural number); an optical sensor that detects the beam deflected by the deflector; a page memory for storing raster image data; a line memory for storing line data, which is data of pixels corresponding to a scanning line on the photosensitive member, read from the page memory; N output buffers corresponding to the N laser light emitting units, respectively; a memory controller; and an image forming apparatus comprising: The memory controller For each period of the detection signal of the optical sensor, writing the line data for N adjacent scanning lines on the photosensitive member from the page memory to a plurality of adjacent addresses on the line memory; selecting from the line memory addresses storing the line data for N scanning lines spaced apart from one another by M scanning lines on the photosensitive member, writing the line data corresponding to each of the N scanning lines read from the selected addresses into the N output buffers, and then outputting the line data to the laser light emitting unit; The image forming apparatus further comprises: a data processing circuit for converting the plurality of line data selected by the memory controller and stored in a plurality of adjacent addresses on the line memory into the line data for one scanning line; The data processing circuit 1. An image forming apparatus comprising: an image forming unit configured to convert the line data for one scanning line so that the resolution in the main scanning direction of the line data is higher than the resolution in the main scanning direction of a plurality of the line data.

2. A photoreceptor; N laser light emitting units (N is a natural number of 2 or more); an incident optical system that converts light emitted from the laser light emitting unit into a beam; a deflector for deflecting the beam from the incident optical system; a scanning optical system that focuses the N beams deflected by the deflector as beam spots at positions on the photosensitive member that are spaced apart by M scanning lines (M is a natural number); an optical sensor that detects the beam deflected by the deflector; a page memory for storing raster image data; a line memory for storing line data, which is data of pixels corresponding to a scanning line on the photosensitive member, read from the page memory; N output buffers corresponding to the N laser light emitting units, respectively; a memory controller; and an image forming apparatus comprising: The memory controller For each period of the detection signal of the optical sensor, writing the line data for N adjacent scanning lines on the photosensitive member from the page memory to a plurality of adjacent addresses on the line memory; selecting from the line memory addresses storing the line data for N scanning lines spaced apart from one another by M scanning lines on the photosensitive member, writing the line data corresponding to each of the N scanning lines read from the selected addresses into the N output buffers, and then outputting the line data to the laser light emitting unit; The image forming apparatus further includes a data processing circuit, The data processing circuit at least one of the plurality of line data selected by the memory controller and stored in a plurality of adjacent addresses on the line memory is set as correction target data; The line data stored in an address adjacent to the address where the correction target data is stored on the line memory is used as reference data; an image forming apparatus that generates the line data for one scanning line by correcting the correction target data based on the reference data;

3. The image forming apparatus described in Claim 2, characterized in that the line data used as the reference data in a certain scan is at least a portion of the line data selected by the memory controller in the previous scan and stored in multiple adjacent addresses on the line memory.

4. The page memory is a DRAM (Dynamic Random Access Memory), 4. The image forming apparatus according to claim 1, wherein the line memory is an SRAM (Static Random Access Memory).

5. an integrated circuit provided with the line memory and the memory controller; 5. The image forming apparatus according to claim 1, wherein the page memory is provided outside the integrated circuit.

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