JP4977434B2 - Image writing apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an image writing apparatus and an image forming apparatus, and more particularly to an image writing apparatus that writes print information on a photosensitive member by a light beam from an LED head and an image forming apparatus having the image writing apparatus.

As a conventional technique related to the present invention, for example, a technique described in Patent Document 1 is known. In this conventional technique, when the pixel density that can be read by a binary image input device such as a scanner is different from the pixel density that can be output by a binary image output device such as a plotter or a display, the binary image output device is particularly suitable. This relates to the conversion of pixel density when the pixel density that can be output is larger than the pixel density that can be read by the binary image input device, and the input binary image is increased at a high density by a predetermined integer multiple by smoothing processing. Means for densification and conversion to a high-density binary image, Density reduction means for reducing the density of the high-density binary image at a predetermined density reduction rate and converting it to a low-density binary image, and low density 2 And a thinning means for performing a thinning process on the value image and outputting it.
JP-A-10-65907

  In general, in a wide-width machine that is an image forming apparatus capable of handling A0 paper, when image data having a pixel density of 400 dpi is subjected to density conversion 1.5 times densely and output to image data having a pixel density of 600 dpi, In this density conversion, since the magnification process is performed by 1.5 times in both the main and sub scanning directions by software, a very long time is required for the magnification process, and improvement thereof has been demanded. It was.

  In order to improve the above-described points, if the configuration is such that the 1.5 × magnification scaling processing in the main / sub scanning directions currently performed by software is performed by hardware, It is considered that the time required for the 1.5 times dense scaling process in both the sub scanning directions can be performed in a time close to real time, so that high speed scaling process is possible.

  In the case of an image forming apparatus in which writing of a wide-width machine that is widely used at present is performed using multi-valued LPH (LED PRINT HEAD) specifications, binary data that is image data from the image information storage unit It is only necessary to convert 400 dpi data to multi-value 600 dpi data and output the data. Various existing 1.5 times dense scaling algorithms can be applied to perform scaling processing with little image quality and deterioration.

  However, in the case of an image forming apparatus using a binary LED array unit, binary 400 dpi data must be converted into binary 600 dpi data, and both main / sub scanning directions using hardware. If you try to perform a high-speed scaling process by performing a scaling process that makes the pixel density 1.5 times dense, you may not be able to input intermediate value data, or when you scale the image using matrix pattern processing The main scanning line width before conversion varies depending on the position of the matrix in the matrix depending on the position of the main scanning line after conversion. However, it is difficult to perform density conversion while maintaining the image quality. There was a problem.

  An object of the present invention is to solve the above-described problems and to perform processing in a main scanning direction by using hardware processing on image data having a binary pixel density of 400 dpi × 400 dpi received from an image information storage unit. By simultaneously correcting the variation in the main scanning line width after conversion, which is generated by performing the scaling process at a density of 5 times and a density of 1.5 times in the sub-scanning direction, and performing a matrix pattern process. Another object of the present invention is to provide an image writing apparatus and an image forming apparatus that can perform 1.5-fold density conversion at high speed to enable high-speed output and can reduce image quality deterioration.

  Another object of the present invention is to perform a density conversion process by performing the above-described matrix pattern process, and then refer to a matrix larger than the matrix referred to by the 1.5-fold density conversion, An object of the present invention is to provide an image writing apparatus and an image forming apparatus capable of reducing the deterioration of image quality by performing correction between matrices in consideration of the correlation with a reference image.

  In order to achieve the above-mentioned object, the first means of the present invention includes a light emitting element array in which a plurality of light emitting elements are arranged in one direction, and an image formed by the light emitted from the light emitting element array on a photoconductor. A plurality of light emitting element array units that are shorter than the length of the photosensitive member in the axial direction, and image data for one line is divided for each light emitting element array unit. In the image writing apparatus that transfers to the light emitting element array unit at a predetermined transfer speed X and drives each light emitting element of the light emitting element array unit, the transfer of the image data to the light emitting element array unit in the sub-scanning direction is performed as described above. The transfer is performed at a transfer rate mX that is m times the transfer rate X (m is a positive integer), and the binary image data of the pixel density Adpi is converted to a density that is {(2B + 1) / 2} (B is a positive integer). Density conversion When the density conversion mode is selected, binary image data of Adpi × Adpi is stored in n (n is a positive integer) memory by n lines, and the n memories [N (2B + 1) / 2] × [n (2B + 1) / 2] conversion is performed while performing image data pattern recognition processing for each n × n matrix of the image data, and [m (2B + 1) / 2] dpi × [(2B + 1) / 2] dpi image data, and simultaneously with this density conversion, simultaneously generate an image in which the line width when the vertical line crosses the matrix seam in the main scanning direction is corrected. Then, the line width of the portion is corrected, and the sub-scanning direction is transferred to each light emitting element array unit as the transfer speed mX.

  According to a second means of the present invention, in the first means, when the density conversion mode is selected, the image writing apparatus stores binary image data of Adpi × Adpi in two lines in two memories. [2m (2B + 1) / 2] × [2 (2B + 1) / 2] conversion while accumulating and performing image data pattern recognition processing for each 2 × 2 matrix on the image data of the two memories The image data is converted into [m (2B + 1) / 2] dpi × [(2B + 1) / 2] dpi image data, and at the same time as the density conversion, the line width when the vertical line straddles the seam of the matrix in the main scanning direction Are generated simultaneously, the line width of the portion is corrected, and the sub-scanning direction is transferred to the light emitting element array units at the transfer speed mX.

  According to a third means of the present invention, in the first or second means, the image writing device is configured to perform a sub-scanning direction of the image data to the light emitting element array unit when the density conversion mode is selected. Transfer is performed at a transfer rate 2X which is twice the transfer rate X.

  According to a fourth means of the present invention, in the first, second or third means, the image writing device outputs binary image data of 400 dpi × 400 dpi when the density conversion mode is selected { Density conversion is performed by (2B + 1) / 2} times.

  According to a fifth means of the present invention, in any one of the first to fourth means, the image writing device transfers the image data {(2B + 1) when the density conversion mode is selected. ) / 2} = density conversion to 1.5 times the density.

  The sixth means of the present invention is the image processing apparatus according to any one of the first to fifth means, wherein the image writing device has a transfer speed mX in the sub-scanning direction that is m times the transfer speed X. In addition to transferring to each light emitting element array unit, the light emitting elements are driven a plurality of times during one main scanning line.

  According to a seventh aspect of the present invention, there is provided an image writing apparatus for forming an electrostatic image on a photoreceptor using a light emitting element array unit, and transferring image data to the light emitting element array unit at a predetermined transfer speed X. Then, in the image writing apparatus that drives each light emitting element of the light emitting element array unit, the transfer of the image data to the light emitting element array unit in the sub-scanning direction is m of the transfer speed X (m is a positive integer). A density conversion mode in which binary image data of the pixel density Adpi is converted to a density of {(2B + 1) / 2} (B is a positive integer) times and output at a double transfer rate mX; When the density conversion mode is selected, binary image data of Adpi × Adpi is stored in k lines (k is a positive integer) in k lines, and n pieces of image data in the k memories are stored. Images from In order to refer to the joints of each n × n matrix while performing pattern recognition processing of the image data for each n × n matrix on the data, a matrix larger than n × n is generated, , While correcting image degradation that occurs at the joints of the matrix, conversion to [mn (2B + 1) / 2] × [n (2B + 1) / 2] matrix is performed, and [m (2B + 1) / 2] Adip × [ (2B + 1) / 2] It is converted into image data of Api, and is transferred to each of the light emitting element array units with the sub-scanning direction as the transfer speed mX.

  According to an eighth means of the present invention, in the seventh means, when the density conversion mode is selected, the image writing device converts binary image data of Adpi × Adpi into k (k is a positive integer). ) Accumulating k lines in each memory, and performing pattern recognition processing of the image data for each n × n matrix with respect to image data from n of the k memories, before and after this main scanning direction The matrix n × 3n matrix in consideration of the n × n matrix pattern is simultaneously referred to to correct the image degradation occurring at the matrix joint, and [mn (2B + 1) / 2] × [n (2B + 1) / 2 ] Is converted into image data of [m (2B + 1) / 2] Adpi × [(2B + 1) / 2] Adpi, and each light emitting element array unit is converted with the sub-scanning direction as the transfer speed mX. Characterized in that it transferred to the Tsu door.

  According to a ninth means of the present invention, in the seventh means, when the density conversion mode is selected, the image writing device converts binary image data of Adpi × Adpi into k (k is a positive integer). ) Accumulating k lines in each memory, and performing pattern recognition processing of the image data for each n × n matrix with respect to image data from n of the k memories, before and after this main scanning direction The matrix n × 3n matrix that takes into account the n × n matrix pattern is also referred to at the same time, and the image degradation occurring at the matrix seam is corrected using a correction pattern that can be arbitrarily set, and [mn (2B + 1) / 2] × [n (2B + 1) / 2] matrix, converted into [m (2B + 1) / 2] Adpi × [(2B + 1) / 2] Api image data, and the sub-scanning direction is transferred. Characterized by transferring said each light emitting element array unit as degrees mX.

  According to a tenth means of the present invention, in the seventh means, when the density conversion mode is selected, the image writing device converts binary image data of Adpi × Adpi into k (k is a positive integer). ) Accumulating k lines in each memory, performing pattern recognition processing of the image data for each n × n matrix for image data from n of the k memories, Further, a matrix of (n + 1) × (n + 2) increased by one line in the peripheral sub-scanning direction and two lines before and after in the main scanning direction is referred to at the same time to correct image degradation occurring at the matrix joint, and [mn (2B + 1 ) / 2] × [n (2B + 1) / 2] matrix, converted into [m (2B + 1) / 2] Adpi × [(2B + 1) / 2] Api image data, and transferred in the sub-scanning direction It transfers to each said light emitting element array unit as speed mX, It is characterized by the above-mentioned.

  According to an eleventh means of the present invention, in the seventh means, when the density conversion mode is selected, the image writing device converts binary image data of Adpi × Adpi into k (k is a positive integer). ) Accumulating k lines in each memory, performing pattern recognition processing of the image data for each n × n matrix for image data from n of the k memories, Further, an image generated at a matrix joint using a correction pattern that can be arbitrarily set by simultaneously referring to a matrix of (n + 1) × (n + 2), which is increased by one line in the peripheral sub-scanning direction and two lines before and after in the main scanning direction. Is corrected and converted into a [mn (2B + 1) / 2] × [n (2B + 1) / 2] matrix, and an image of [m (2B + 1) / 2] Adpi × [(2B + 1) / 2] Adpi The data is converted into data, and the sub-scanning direction is transferred to each light emitting element array unit at the transfer speed mX.

  The twelfth means of the present invention is the image processing apparatus according to any one of the seventh to eleventh means, wherein the image writing device is an image to be converted when the density conversion mode is selected. The matrix seam correction operation is selected in accordance with this, and the matrix seam correction operation is selected for each machine and model in which the image writing apparatus is incorporated.

  According to a thirteenth aspect of the present invention, there is provided a developer in which an image writing unit irradiates light on the photosensitive member to form an electrostatic latent image on the photosensitive member, and the electrostatic latent image is developed with a developer. In an image forming apparatus that finally transfers an image to a sheet recording medium to form an image, the image writing device of any one of the first to twelfth means is used as the image writing unit. It is characterized by being necessary.

  According to the present invention, various density conversions can be performed at high speed, and deterioration in image quality can be reduced.

  Hereinafter, embodiments of an image writing apparatus and an image forming apparatus according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a functional configuration of the image forming apparatus according to the first embodiment of the present invention, and FIG. 2 is a block diagram showing a hardware configuration of the image forming apparatus according to the first embodiment of the present invention.

  As shown in FIG. 1, an image forming apparatus according to an embodiment of the present invention stores a document reading unit 100 as a reading unit that reads a document, and an image information storage unit 300 as a storage unit that stores the read document information. The image forming apparatus includes a writing unit 500 that executes a series of processes for copying the recorded information onto transfer paper, and a copying apparatus 200 that is an engine that records image data from the writing unit 500. The image information storage unit 300 includes an image memory unit 301, a system control device 302 that controls the entire image forming apparatus, and a printer driving device 300. Also. The system controller 302 is connected to an operation device 400 as an operation means for performing key input.

  Next, the document reading apparatus 100 will be described with reference to FIGS.

  In FIGS. 1 and 2, when the operator inserts a document from the insertion slot, the document is conveyed between the contact sensor 101 and the white roller 23 by the rotation of the roller 21. The document being conveyed is irradiated with light by the LED element attached to the contact sensor 101, and the reflected image forms an image on the contact sensor 101 to read document image information.

  As shown in FIG. 1, the contact sensor 101 converts the formed original image into an analog electrical signal, and this electrical signal is amplified by the image amplification circuit 102. The A / D conversion circuit 103 converts the image signal amplified by the image amplification circuit 102 into a multi-value digital image signal for each pixel. This digital image signal is output from the A / D conversion circuit 103 in synchronization with the clock output from the synchronization control circuit 106, and the shading correction circuit 104 causes the light amount unevenness of the LED element, the sensitivity unevenness of the contact sensor 101, and the like. The distortion due to is corrected.

  The digital image information corrected by the shading correction circuit 104 is converted into digital recording image information by the image processing circuit 105 and then written in the image memory unit 301 as a storage unit in the image information storage unit 300. The reading control circuit 107 controls the synchronization control circuit 106 and the like in the document reading apparatus 100, and the scanner driving device 108 drives a motor and the like that rotate the roller 21, the white roller 23 and the like in the reading apparatus 100.

  Next, the configuration of the system control device 302 and the writing device 500 for controlling a series of processes for forming an image to be transferred by image information written in the image memory unit 301 will be described.

  The system control circuit 302 has a function of performing overall control of the image forming apparatus according to the embodiment of the present invention, and the density conversion unit 502 constituting the reading control circuit 107, the synchronization control circuit 106, the image memory unit 301, and the writing unit 500. Then, image data transfer to the LED writing control circuit 505 is controlled, and the drive control circuit 504 is driven by a motor or the like via the scanner driving device 108 and the printer driving device 303 to smoothly control the conveyance of the document and the transfer paper. .

  The writing unit 500 receives the image signal transferred from the image memory unit 301 by the synchronization signal clock by the density conversion unit 502 and passes the image signal to the LED writing control circuit 505 as it is, or performs density conversion and passes the LED signal. The received data is divided into the LED array unit 1, 2, and 3, and necessary image correction is performed, and the LED array (LPH) 503-1 of the LED array unit 503 as the light emitting element array unit. 503-3 converts to infrared light and outputs it.

  Next, an image forming process in the embodiment of the present invention will be described with reference to FIG.

  In FIG. 2, a charging device 24 is a charging device called a scorotron charger with a grid that uniformly charges a drum-like photoconductor 25 as an image carrier to −2500 V. The photoconductor 25 is driven by a motor (not shown). Driven by rotation.

  The LED array unit 503 includes a plurality of LED elements arranged in an array in the main scanning direction by arraying the LED array units 503-1 to 503-3 in a one-dimensional manner, and image information from the LED write control circuit 505. Based on the above, the LEDs of the LED array units 503-1 to 503-3 emit light and irradiate the photosensitive member 25 with the light through the SELFOC lens array which is an optical element.

  When the photoconductor 25 is irradiated with light based on digital image information from the LED array unit 503, the surface charge flows to the ground due to a photoconductive phenomenon and disappears. Here, in the LED array unit 503, the LED element does not emit light in a portion where the image density of the original is low, and the LED element emits light in a portion where the image density of the original is high. Thereby, an electrostatic latent image corresponding to the density of the original image is formed on the light irradiation portion on the photosensitive member 25. The electrostatic latent image on the photoreceptor 25 is developed by the developing device 27 to become a toner image. In the developing device 27, since the toner inside is negatively charged by stirring and a voltage of −700 V is applied as a bias, the toner adheres only to the light irradiated portion on the photoconductor 25.

  On the other hand, the transfer paper as a sheet-like recording medium is selectively fed to the registration roller 31 from the three paper feed bases 28 to 30 and the manual feed unit, and is sent out at a predetermined timing by the registration roller 31 to be transferred to the photosensitive member 25. Pass through the bottom. At this time, the toner image on the photoconductor 25 is transferred by the transfer charger 32 as a transfer unit. Next, the transfer paper is separated from the photosensitive member 25 by the separation charger 33 and sent to the fixing device 35 by the conveying belt 34, where the toner is fixed. The transfer sheet on which the toner is fixed is discharged out of the apparatus by discharge rollers 36 and 37.

  FIG. 3 is a diagram showing a detailed configuration of the writing unit 500. Next, the flow of the entire image data of the writing unit 500 will be described with reference to FIG.

  The writing unit 500 includes a density conversion unit 502, an LED writing control circuit 505, an LED array unit 1 503-1, an LED array unit 2 503-2, and an LED array unit 3 503-3 (hereinafter referred to as LPH). .

  First, EVEN 1-bit image data and ODD 1-bit image data are simultaneously sent from the image information storage unit 301 to the writing unit 500. The transferred image data is pattern-recognized by the density converter 502 and output as 2-bit encoded data. The output main scanning data is serial / parallel converted from 2 pixels to 4 pixels by a data converter 5051 that performs serial / parallel conversion in units of 4 pixels, and three SRAMs (SRAM A− 1 to A-3), the data for one line is divided and written as one pixel of 4 pixels (2 * 4 = 8 bit unit). At this time, control of the writing range in the main scanning direction (1 dot correction) and position correction between LPHs are performed to align the main scanning resist. The left end of the image is the reference.

  Next, the image data for one line written in the three SRAMs of the group A are read out simultaneously. The read address starts from 0, counts 1919, and 1920 * 4 = 7680 dots for one LPH is transferred.

  The LPH to be used is configured to transfer all 7680 dots separately for EVEN data and ODD data. Therefore, taking LPH1 as an example, the 1-address 4-pixel data read from the SRAM is 0EVEN / 1ODD / 2EVEN / 3ODD, so the next 2 addresses are read and EVEN data is selected. As a result, data of 0EVEN / 2EVEN / 4EVEN / 6EVEN is selected and transferred to the next stage. Here, the unit of 2 bits per pixel is equivalent to 4 pixels, but 1 pixel is converted to 1 bit (2-bit coding is pattern recognition). This is repeated for addresses 0-1919 to select 3840 pixels for EVEN data only.

  Next, addresses 0 to 1919 are read from the SRAM again, and this time, ODD data corresponding to 3840 pixels is selected. This control makes it possible to read out one line data. Further, the third address reading is performed, EVEN data is selected, and ODD data is selected in the fourth address reading. As a result, data ((3840 + 3840) * 2 times) is read twice in one line.

  While data is being read from the A group SRAM, the next second line performs a toggle operation in which data is written to the B group SRAM (SRAM B-1 to B-3). Further, LPH1 and LPH3 are reversely mounted in LPH and the transfer direction is from right to left. Depending on the register setting, it is possible to select from EVEN or ODD.

  Next, the LPH image data read from the main scanning SRAM, that is, the LPH1 data is transferred to the LPH output, and the LPH2 and 3 image data are transferred to the line memory.

  Due to the mechanical layout, the data from LPH2 is shifted from the data from LPH1 by 17.5 mm (413 lines) in the sub-scanning direction, and the data from LPH3 is 0.4 mm (9 lines) from the data from LPH1. Deviation in the sub-scanning direction.

  FIG. 4 is a diagram for explaining the position of image data output from LPH1 to LPH3. Next, the position of image data from each LPH will be described with reference to FIG.

(1) Provide a margin of 120 dots on both sides (a margin for shifting, etc.) (5 mm shift is possible → ± 2 mm in control).

(2) At the joint between the heads, LPH1 and 3 are overlapped by 524 dots and LPH2 is overlapped by 68 dots, and the respective image effective areas are controlled so that the images do not overlap.

(3) The position of the image data of LPH2 is fixed, and the position of the head is corrected by shifting the images of LPH1 and 3 (with the effective area width fixed).

(4) In order to shift the LPH1 and 3 images, it is possible to designate write addresses to the A group SRAM and the B group SRAM.

(5) In order to shorten the distance between the LPHs as much as possible (reduce the image delay memory), the LPH2 is mounted in the opposite direction to the LPH1 and 3 by 180 degrees.

(6) Image transfer from the LED writing control unit 505 is from left to right, but with the LPH2 described in (5), LPH1 and 3 are image transfer from right to left, and LPH2 is left In the embodiment of the present invention, which is an image transfer from right to right, correction is performed by delaying in the sub-scanning direction between the LPH from the physical arrangement of the LPH as described above by delaying the FIFO and SDRAM. I will do it. In other words, FIFOs are arranged before and after the SDRAM to perform the above-described control.

  Returning to the reference in FIG. 3, first, the image output from the image data RAM unit 5052 is made by latching the data for four pixels converted from the SRAM four times in the first stage FIFOs 5053 and 5054 with the data amount for one line. It is input as 16 pixels. Then, the data is written into the SDRAM 5055 while writing. The SDRAM 5055 is a line memory. LPH2 controls the delayed sub-scan line by reading the first line after writing 413 lines as an example. Further, the read data is written from the SDRAM 5055 to the subsequent FIFOs 5056 and 5057, and is read in accordance with the LPH control timing on the next line, that is, the 414th line.

  Also, the printing control differs between the copy mode and the printer mode. In the copy mode, data for one line is transferred to one line, and the LED lighting duty is turned on twice for EVEN data and ODD data at the same duty. However, in the printer mode, the data for one line is transferred twice per line to convert the data, and the LED lighting duty is controlled by the ratio control (the ratio of 3: 1 in the copy mode). The number of times of lighting is twice that of the copy mode, and four times of EVEN / ODD / EVEN / ODD. The described control form is sub-scanning pseudo multi-value control, in which data transfer twice per line + data comparison + duty ratio control is possible.

  FIG. 5 is a block diagram showing a detailed configuration of the density converter 502. Next, the density converter 502 will be described in detail with reference to FIG.

  As shown in FIG. 5, the density conversion unit 502 includes a GATE control 502-1, a memory control 502-2, a density conversion processing unit 502-3, and a main / sub trim processing unit 502-4 for masking portions other than the image area. It is configured.

  Normally, the mode is determined by the value of a register dense_r (not shown) from the CPU I / F. If the value is 0, the normal output mode is set, and if it is 1, the 1.5-fold density conversion mode is set. Since the image data of LSYNC_0 passed to the image memory unit 301 of the image information storage unit 300 according to the mode and the image data of LSYNC delivered from the image information storage unit 300 in the density conversion mode are thinned out, the GATE control The unit 502-1 interpolates LSYNC image data when passing the image data to the LED image writing control unit 505. Since the GATE control unit 502-1 uses a polygon for forming an image, the GATE control unit 502-1 passes a timing signal LSYNC0 for capturing image data from the image information storage unit 300 to the image information storage unit 300. The GATE control unit 502-1 also generates a dummy FGATE separately from the LSYNC image data.

  FIG. 6 is a diagram showing how image data is interpolated in the GATE control unit 502-1. 6 shows a synchronization signal to be passed to the image information storage unit 300 in the case of the 1.5 × dense mode in the case of 600 dpi, and a dotted ellipse in the case of the 1.5 × dense mode. The data at the position indicated by is thinned out. The reason for thinning out the data is to receive the data for two lines and generate the data for three lines, so that the data is not received after the data for two lines is received. The thinned-out image data is supplemented with the thinned-out data as shown in the lowermost part of FIG. 6 and is transferred to the LED image writing control unit 505.

  Next, the memory control unit 502-2 will be described. The memory control unit 502-2 generates an image matrix according to the density conversion mode set by the register dense_r. Its main functions are as follows.

(A) Mask data write The read / write of the line memory is performed in two-pixel parallel (EVEN-ODD). That is, image data of 21600 dots per line is written for each PLSYNC_N into a line memory having addresses 0 to 10799 and a width of 2 bits. If there is no assertion of the PFGATE_N signal and the PLGATE_N signal indicating whether to write image data (not shown) (whether to output to LPH), the masked data is written to the line memory. In addition, when the assertion of the PLGATE_N signal does not occur within 32 clocks from PLSYNC_N, the writing to the line memory is forcibly started. Thus, before the PFGATE_N signal is asserted, the six line memories 0 to 6 are filled with the mask data (= 0).

(B) Image Data Write The mask is released during the enable period of the PFGATE_N signal and the PLGATE_N signal, and the image data is written into the memory.

(C) Data Read and Image Matrix Generation Data is read from the line memory every plsync_n (PLSYNC_N is interpolated to a 600 dpi interval).

  The matrix size at each magnification is 5 × 5 when the magnification is single density, ordinarily, and 2 × 2 when the magnification is 1.5 times density. A matrix of 2 × 2 size is generated by reading two of the five memories that are not performing the write operation. For example, when the line memory 1 is in a write operation, the 2 × 2 matrix is distributed by reading the line memory 4 to be the first line of the image matrix and reading the line memory 5 to be the second line of the image matrix. And so on.

  7 to 12 are timing charts for explaining the image matrix generation and the matrix read method. Next, these will be explained. In these figures, LSINC_N is a line synchronization signal, FGATE_N is an image area signal, LGATE_N is a line gate signal, PKDE and PKDO are even and odd image signals, lmem_wrst is a line memory write reset, lmem_wen is a line memory write enable, lmem_num is the line memory number, lmem_date is the write data, lmem_rst is the line memory read reset, lmem_ren is the line memory read enable, mx_date0 to 4 are matrix data, pisync_n is the line synchronization signal, pfgate_n is the image area signal, and plgate_n is the line gate Signals pkde and pkdo indicate even and odd image signals, respectively.

  FIG. 7 is a timing chart at the time when the PFGATE_N signal is asserted in the case of single density without scaling. In the writing to the line memory, the mask data 0 is sequentially written in the line memories 0 to 5 until the image area signal FGATE_N falls and the top timing of the page is reached, and then the even and odd images are written. The signals PKDE and PKDO are written so that the line memories 0 to 5 are repeatedly used. In this case, the line memory to be written is designated by the line memory number lmem_num.

  Further, the reading of the line memory is started at a timing delayed by three lines with respect to the writing, and 0 as mask data is read until the timing of the top of the page, and then the even and odd image signals pkde. , Pkdo is read out. Then, a 5 × 5 image matrix is generated in the above read control.

  FIG. 8 is a timing chart when the PFGATE_N signal is negated in the case of single density without zooming. In the example shown in FIG. 8, the even and odd image signals PKDE and PKDO are repeatedly written using the line memories 0 to 5 until the image end signal FGATE_N rises to the page end timing, and thereafter Therefore, 0 as mask data is written into the line memories 0 to 5. As in the case of FIG. 7, the reading is started at a timing delayed by three lines, and the even and odd image signals pkde and pkdo are read until the final line is reached, and thereafter, mask data 0 is set. This is done to be read out.

  FIGS. 9 and 10 are timing charts when the PFGATE_N signal is asserted in the case of performing 1.5 times the variable magnification. In the case of 1.5 times the density, one of the three line gate signals LSIC_N is thinned out as already described. The example shown in FIG. 9 is an example in which the timing of the top of the page at which the image area signal FGATE_N falls is the timing at which the first line can be written to the line memory by the next line gate signal LSINC_N after thinning. In the example shown in FIG. 10, the first line can be written to the line memory by the line gate signal LSINC_N at which the next line gate signal LSINC_N is thinned out at the timing of the top of the page where the image area signal FGATE_N falls. This is an example of timing. In either case, the mask data 0 is written in the line memory until the image area signal FGATE_N falls. When the image area signal FGATE_N falls, the line memory number lmem_num is set. After the reset, the even and odd image signals PKDE and PKDO are sequentially written using the line memories 0 to 5 repeatedly. The reading of the line memory is started at a timing delayed by three lines with respect to the writing in accordance with the 1.5-times dense line synchronization signal pisync_n that has not been thinned out, and is 0 as mask data until the head of the page is reached. Is read out, and then the even and odd image signals pkde and pkdo are read out. Then, a 2 × 2 image matrix is generated in the above-described reading control.

  FIG. 11 and FIG. 12 are timing charts when the PFGATE_N signal is negated in the case of performing 1.5 times the variable magnification. Also in this case, as in the case of FIGS. 9 and 10, one of the three line gate signals LSIC_N is thinned out. The example shown in FIG. 11 is an example in which the page end timing when the image area signal FGATE_N rises becomes the timing at which 0, which is mask data, can be written in the line memory by the next line gate signal LSINC_N after thinning. In the example shown in FIG. 11, the page end timing when the image area signal FGATE_N rises is written in the line memory with 0 as mask data by the line gate signal LSINC_N from which the next line gate signal LSINC_N is thinned out. This is an example of when it is possible. In either case, until the image area signal FGATE_N rises, the even and odd image signals PKDE and PKDO are written repeatedly using the line memories 0 to 5, and the image area signal FGATE_N rises. Then, 0, which is mask data, is written in the line memory. The line memory reading is started at a timing delayed by three lines with respect to the writing in accordance with the 1.5-times dense line synchronization signal pisync_n that has not been thinned out, and the even and odd images until the page end timing is reached. The signals pkde and pkdo are read out, and thereafter, mask data 0 is read out. Then, a 2 × 2 image matrix is generated in the above-described reading control.

  FIG. 13 is a timing chart for explaining the operation of converting 2 pixels into 3 pixels in the main scanning direction. This operation is basically the same as the operation in the sub-scanning direction described above and is already well known. The operation here is an operation of reading out two pixels of even and odd in one clock and generating an image matrix by outputting four pixels for two clocks as six pixels. For this reason, the count-up of the read address is performed so that the count is incremented by 2 in 3 clocks, specifically, the 3rd clock is not counted.

  Next, the density conversion processing unit 502-3 will be described. As shown in FIG. 5, the density conversion processing unit 502-3 includes a smoothing output unit, a 1.5-fold density processing unit, a selector, and a format conversion unit, and is set by a register dense_r. The normal output mode and the 1.5-fold density conversion mode are selected according to the mode to be performed. When the normal output mode is selected, the density conversion processing unit 502-3 converts the image data of 1 pixel 2 values 1 bit into 1 pixel 2 values 2 bits and outputs it to the main / sub trim processing unit 502-4. When 1.5 times density conversion mode is selected, 1.5 times density processing is performed.

  FIG. 14 is a block diagram showing a configuration of a 1.5 × dense processing unit, and FIG. 15 shows a state in which the 1.5 × dense processing unit divides an image into a 3 × 6 matrix and outputs a 2 × 2 image matrix. FIG. 16 is a diagram showing the contents of a register that is referred to when a 2 × 2 image matrix is divided into a 3 × 6 matrix and output. Next, details of 1.5-fold density conversion will be described. Explained.

  As illustrated in FIG. 14, the 1.5 × density processing unit 502-31 includes a 1.5 × density conversion unit 502-32, a main scanning line correction image generation unit 502-33, and an image correction unit 502-34. ing.

  As shown in FIG. 15, the 1.5 density conversion unit 502-32 divides an image into an output 3 × 6 matrix set by the registers Pixelpattern 1 to 9 shown in FIG. 16 while referring to a 2 × 2 image matrix. I do. As shown in FIG. 15, since the 2 × 2 image matrix is a pattern of 4 pixels, there are a total of 16 patterns. These 2 × 2 patterns are 3 × 6 patterns as shown on the right side of each pattern, but the 2 × 2 pattern shown in black is again 3 × 6 The pattern indicated by black in the pattern is a fixed black pattern, and the part indicating the register number around the position indicated by black in the 3 × 6 pattern is black and black according to the contents of the register. It is decided whether to make it white. The registers for determining whether to make black or white are the registers Pixelpatterns 1 to 9 shown in FIG. 16, and by applying the setting information, each pattern of the 2 × 2 image matrix becomes the pattern. The image is generated by being divided into an output 3 × 6 matrix as shown on the right side of FIG.

  FIGS. 17 and 18 are diagrams for explaining an operation in which the main scanning line correction image generation unit 502-33 generates a 3 × 6 line correction output image matrix from a 2 × 2 input image matrix.

  As shown in FIGS. 17 and 18, the main scanning line corrected image generation unit 502-33 includes a line counter FCNT [2: 0] in the sub-scanning direction, a line detection flag T 1 for the first line of the image matrix, and a second one. A 3 × 6 line correction output image matrix is generated from the 2 × 2 input image matrix using the line detection flag T2 for the line.

  When FCNT = 1, the main scanning line correction image generation unit 502-33 first generates the first line and the second line of the output image matrix. When this value is 1 and the line is terminated using the main scanning line detection flag T1 with reference to the first line of the input image matrix, the line width of the output image is corrected by thinning out one pixel at the end of the line. FIG. 17A shows a state of correcting the arrangement of the pixels of the first line when FCNT = 1, and the correction method differs depending on the value of the main scanning line detection flag T1. Show.

  When FCNT = 2, the main scanning line correction image generation unit 502-33 generates the third line and the fourth line of the output image matrix. In other words, the main scanning line corrected image generation unit 502-33 generates the third line of the output image matrix in the same manner as described above with reference to the first line of the input image matrix and the value of T1, and the input line The fourth line of the output image matrix is generated in the same manner as described above with reference to the second line of the image matrix and the value of T2. FIG. 18 shows a state where the third line and the fourth line of the processed image matrix are generated by correcting the arrangement of the pixels of the first line and the second line when FCNT = 2.

  When FCNT = 3, the main scanning line correction image generation unit 502-33 refers to the second line of the input image matrix and the value of T2 as in the case of FIG. The fifth and sixth lines are generated. The state in this case is shown in FIG.

  The image correction unit 502-34 combines the image generated by the processing in the 1.5 × density conversion unit 502-32 and the image generated by the processing in the main scanning line correction image generation unit 502-33. . At this time, the image correction unit 502-34 gives priority to the image generated by the main scanning line correction processing unit only at the end of the main scanning line. In other cases, the image correction unit 502-34 is corrected by the contents set in the register pixels 1 to 9 described above. Image composition is performed so that the state of the captured image is reflected.

  This image synthesis is performed by first recognizing whether or not the image is a portion where thinning occurs on the output image matrix using the value of the main scanning counter SCNT [2: 0]. Line thinning occurs when SCNT = 2.

  FIG. 19 is a diagram for explaining an example of image composition when SCNT = 1 or 3. FIG. 20 is a diagram for explaining an example of image composition when SCNT = 2.

  In the case of SCNT = 1 or 3, as shown in FIG. 19, the image generated by the 1.5-fold density converter 502-32 is always preferentially combined. FIG. 19 shows a set of output pixels from the 1.5 × density conversion unit 502-32 and output pixels from the main scanning line correction image generation unit 502-33 when SCNT = 1 or 3. The state of the pixels output from the image correction unit 502-34 is shown.

  When SCNT = 2, as shown in FIG. 20, when the image generated by the main scanning line correction image generation unit 502-33 is white, priority is given to the image, and when the image is black, the 1.5-fold density conversion unit 502 is provided. The image generated at -32 is preferentially combined. FIG. 20 shows a representative set of output pixels from the 1.5 × density conversion unit 502-32 and output pixels from the main scanning line correction image generation unit 502-33 when SCNT = 2. On the other hand, the state of the pixels output from the image correction unit 502-34 is shown.

  FIG. 21 is a flowchart for explaining the entire processing operation of the density conversion unit 502 mainly including the processing operation in the 1.5-times dense processing unit 502-31. Next, this will be described.

(1) First, in loop 1, image generation processing is started until the sub-scanning line ends the document, and in loop 2, main scanning image generation processing is performed until the main scanning line ends the document length. Start. As a result, binary 2-line image data is sequentially input to the 1.5 × density conversion unit 502-32 and the main scanning line corrected image generation unit 502-33 (steps 2101 and 2102).

(2) Next, the value of the 1.5-times dense main scanning counter SCNT [2: 0] is checked to determine whether SCNT = 1 or 3 or SCNT = 2. If SCNT = 2, 1 Referring to the output target pixel from the 5-fold density conversion unit 502-32, it is determined whether the target pixel is white or black (steps 2103 and 2104).

(3) If SCNT = 1 or 3 in the determination in step 2103, or if the target pixel is white in the determination in step 2104, the image correction unit 502-34 has a 1.5-fold density conversion unit 502. The pixel data output from -32 is output with priority (step 2105).

(4) If it is determined in step 2104 that the target pixel is black, the output target pixel from the main scanning line correction image generation unit 502-33 is referred to, and the output pixel of the interpolation unit is white or black. It is determined whether or not there is (step 2106).

(5) If it is determined in step 2106 that the output pixel of the interpolation unit is white, the image correction unit 502-34 outputs the target pixel as white, and the output pixel of the interpolation unit is black. If it is, the target pixel is output as black (steps 2107 and 2108).

  Up to this point, the first embodiment of the present invention has been described. Next, the second embodiment of the present invention will be described. Also in the second embodiment, the functional configuration of the image forming apparatus, the hardware configuration of the image forming apparatus, and the detailed configuration of the writing unit 500 are the same as those in the first embodiment described with reference to FIGS. The positions of the image data configured and output from LPH1 to LPH3 are also the same as described with reference to FIG.

  According to the first embodiment of the present invention described above, by performing the correction operation at the time of 1.5-fold density conversion, it is possible to prevent variations in the line width of main scanning, and to improve image quality. Can do.

  FIG. 22 is a block diagram showing a detailed configuration of the density conversion unit 502 according to the second embodiment of the present invention. The density conversion unit 502 in the second embodiment includes an image recognition unit between the memory control 502-2 and the density conversion processing unit 502-3 of the density conversion unit 502 in the first embodiment described with reference to FIG. The other configurations are the same as those in FIG.

  The mode of the density conversion unit in the second embodiment is also determined by the value of the register dense_r (not shown) from the CPU I / F. In the second embodiment, if the value is 0, the normal output mode (through mode) is selected. ) 1 for single density mode, 2 for double density mode, 3 for 3 density conversion mode, 4 for 1.5 density mode, 5 for 1.5 density (inter-matrix correction a) If the mode is 6, the mode is 1.5 times dense (inter-matrix correction b) mode and conversion is performed densely.

  In the above description, the GATE control unit 502-1 sets LSYNC_0 to be passed to the image information storage unit 301 according to the print mode other than the 1.5 times density conversion or the image output mode set according to the 1.5 times density conversion mode. Since the LSYNC from the image information storage unit is thinned out in the generation or density conversion mode, it is necessary to interpolate the LSYNC when passing it to the LED image writing control unit 502, so that processing is performed. A dummy FGATE is also generated in this block in addition to LSYNC. The thinning-out in the case of the 1.5-fold density conversion mode that is the object of the second embodiment of the present invention described is the same as that described with reference to FIG. The main functions of the memory control unit 502-2 are the same as those described in the first embodiment.

  The matrix size at each magnification is a single density, usually 5 × 5, and a magnification of 1.5 × is 2 × 2, 6 × 2, and 4 × 2. At the time of 1.5-fold density conversion, a 6 × 3 pattern matrix is generated, and then the necessary matrix is referenced in each mode. The read / write operation of the memory is an operation of reading three of the five memories not performing the write operation.

  23 and 24 are timing charts for explaining the image matrix generation and matrix reading method. FIG. 23 is a timing chart when the PFGATE_N signal is asserted in the case of 1.5 times the variable magnification. FIG. FIG. 11 is a timing chart when the PFGATE_N signal is negated in the case of performing a variable magnification of 5 ×. Next, these will be described. The reference numerals of the signals in these drawings are the same as those described with reference to FIGS. Further, these timing charts are basically the same as those in the first embodiment described with reference to FIGS. 9 and 11, except that the generated image matrix is read from three line memories. It is a point generated from data.

  FIG. 25 is a diagram for explaining a process in which the image recognition unit 502-5 discriminates the type of image. Next, what kind of image the image currently referenced by the image recognition unit 502-5 is. Processing for determination will be described.

  As shown in FIG. 25A, the image recognizing unit 502-5 refers to the constant area window length N in the main scanning direction in the image and counts changing points changing from white to black and from black to white. As shown in FIG. 25B, halftone dot detection is performed based on whether or not the number of amith1 [7: 0] set in the register in advance is exceeded, and two types of halftone dot portions a and b and a character / line image are displayed. The part c is detected. Such image recognition is performed on the first line and the second line, and the state is set to imgtype [1: 0] and passed to the 1.5-fold density conversion unit. imgtype [1: 0] represents a combination of image discrimination results by its value. That is, when the value of imgtype [1: 0] is 1, the state of the image is the first line: character / line drawing, the second line: character / line drawing, and in the case of 2, the state of the image is the first line Either one of the two lines is a halftone dot, and in the case of 3, the state of the image is a halftone dot on the first line and a halftone dot on the second line. Note that the size of the window length N can also be arbitrarily set by the register amize [7: 0].

  As shown in FIG. 22, the density conversion processing unit 502-3 includes a smoothing processing unit 502-35, a 1.5 double density processing unit 502-31, an image selector 502-36, and a format conversion unit 502-37. Yes. The density conversion processing unit 502-3 selects each density conversion mode and matrix joint correction processing set by the register dense_r, and performs processing corresponding thereto.

  That is, when the through mode is selected, the density conversion processing unit 502-3 simply converts 1-pixel binary 1-bit image data into 1-pixel binary 2-bit and outputs the result. When single density, double density, or triple density is selected, the density conversion processing unit 502-3 performs necessary density conversion processing on the input image, and at the same time, 1-pixel binary 1-bit image data. Is converted into one pixel and two bits and output to the main / sub trim processing unit. When the 1.5-fold density conversion mode is selected, 1.5-fold density processing is performed.

  FIG. 26 is a block diagram showing a detailed configuration of the 1.5-times dense processing unit 502-31. The 1.5-fold density processing unit 502-31 is roughly divided into two functions. A pattern is formed using image data for three lines in the sub-scanning direction of output data from the line memory via the image recognition unit. A pattern matrix generation unit 502-311 that generates a matrix and a pattern recognition & output image generation unit 502-312 that recognizes the generated pattern matrix and generates an output image of the target pixel.

  FIG. 27 is a timing chart for explaining an operation in which the pattern matrix generation unit 502-311 generates a pattern matrix. As shown in FIG. 26, the pattern matrix generation unit 502-311 latches the input images for three lines and receives them to generate a pattern matrix. As shown in FIG. 27, at the time of 1.5-fold density conversion, data for 4 pixels is sent from the preceding line memory at 3 clk, so that the pattern matrix according to the value of SDCCNT for main scanning direction recognition Is generated. That is, when SDCCNT = 1, a matrix is generated using data of 2, 3, and 4 latches, and when SDCCNT = 2, 1, 2, and 4 latches of data are used. If SDCCNT = 3, the matrix holds the values so far. Such an operation is performed on the data of the first line, the second line, and the third line, respectively, to generate a 6 × 3 data matrix.

  FIG. 28 is a diagram illustrating how the 1.5 × dense processing unit divides a 2 × 2 image matrix into a 3 × 6 matrix and outputs the image, and FIG. 29 illustrates a 2 × 2 image matrix that is 3 × 6. It is a figure which shows the content of the register referred when dividing | segmenting and outputting an image to a matrix, and is demonstrated in detail next about 1.5 times dense conversion. This processing is performed by the pattern recognition & output image generation unit 502-312 of the 1.5 × density processing unit 502-31. In the case of the basic 1.5 × density conversion processing, as shown in FIG. The output 3 arbitrarily set in the registers Pixelpatterns 1 to 12 set by the CPU as shown in FIG. 29 while referring to all 16 patterns of the 2 × 2 image matrix at the center of the generated 6 × 3 pattern matrix. A matrix of × 6 output images is generated and 1.5 times density conversion processing is performed. This process is basically the same as the process in the first embodiment of the present invention described with reference to FIGS.

  30 and 31 are diagrams for explaining the correction operation a between the matrices. Next, the correction operation a between the matrices will be described with reference to these drawings. The correction operation a between the matrixes is performed by performing the basic 1.5 times density conversion as described above to generate a 3 × 6 output image matrix, and is currently referred to in the 1.5 times density conversion process. The 2 × 2 matrix and the 2 × 2 matrix before and after the main scanning direction are defined as a 6 × 2 matrix, and this 6 × 2 matrix is simultaneously referred to as shown in FIG. A correction image 3 × 6 pixels of a matrix seam arbitrarily set in registers op1 to op8 set by the CPU is generated. At this time, if the output imgtype [1: 0] of the image discriminating unit is larger than the set imgth [1: 0], the output image of the basic 1.5 × density conversion and the corrected image are combined to generate a 1.5 × density conversion. When the output image type [1: 0] of the image discriminating unit is smaller than the set image [1: 0], the output image of the basic 1.5-fold density conversion is output as it is. FIG. 30 and FIG. 31A show examples of 6 × 2 matrix reference patterns and the status of output image setting by a register.

  FIG. 32 is a diagram for explaining the correction operation b between the matrices, and FIG. 33 is a diagram showing the contents of the register referred to in the correction operation between the matrices. Next, the correction between the matrices is described with reference to these diagrams. The operation b will be described. This inter-matrix correction operation b performs the basic 1.5-fold density conversion as described above, generates a 3 × 6 output image matrix, and is currently referred to in the 1.5-fold density conversion process. The 2 × 2 matrix, one pixel before and after the main scanning direction and +1 line in the sub-scanning direction are defined as a 4 × 3 matrix, and this 4 × 3 matrix is simultaneously referred to and shown in FIG. A corrected image 3 × 6 pixels of a matrix seam arbitrarily set in the registers op9 to op11 set by the CPU is generated. When the corrected image is generated, the registers tp1 to 10800 that always indicate the status of the current reference pattern are updated / referenced, the reference pattern is selected accordingly, and the corrected image is generated and the status is updated with the referenced pattern. These two operations are performed simultaneously.

  Also in this case, as in the case described with reference to FIGS. 30 and 31, when the output imgtype [1: 0] of the image discrimination unit is larger than the set imgth [1: 0], the basic 1.5-fold density conversion is performed. When the output image and the corrected image are combined and output as an output image of 1.5 times density conversion, and the output imgtype [1: 0] of the image discrimination unit is smaller than the set imgth [1: 0], the basic 1.5 The output image of double density conversion is output as it is. FIG. 32 shows an example of a 4 × 3 matrix reference pattern and the status of output image setting by a register.

  The main / sub-trim processing unit 502-4 performs trim processing on the image in the main / sub-scanning direction while masking portions other than the image area.

  The above-described second embodiment of the present invention has been described as being applied when a plurality of light emitting element array units shorter than the axial length of the photoconductor are arranged in the main scanning direction. It can also be applied to a single case.

  Further, the density conversion magnification in the first and second embodiments of the present invention is not limited to 1.5 times, and the pixel density from the reading device is not limited to 400 dpi, and is arbitrary. It's okay.

  According to the second embodiment of the present invention as described above, by performing the correction operation at the time of 1.5-fold density conversion, it is possible to smoothly correct a conspicuous portion of the step of the diagonal line and improve the image quality. be able to.

  According to the above-described embodiment of the present invention, it is possible to provide an image writing apparatus and an image forming apparatus that can perform various density conversions at high speed and can reduce deterioration in image quality.

1 is a block diagram illustrating a functional configuration of an image forming apparatus according to a first embodiment of the present invention. 1 is a block diagram illustrating a hardware configuration of an image forming apparatus according to a first embodiment of the present invention. It is a figure which shows the detailed structure of a writing part. It is a figure explaining the position of the image data output from LPH1-LPH3. It is a block diagram which shows the detailed structure of a density conversion part. It is a figure which shows the mode of the interpolation of the image data in a GATE control part. It is a timing chart when the PFGATE_N signal is asserted in the case of single density without zooming. It is a timing chart when the PFGATE_N signal is negated in the case of single density without zooming. FIG. 10 is a timing chart (part 1) when a PFGATE_N signal is asserted in the case of performing 1.5 times the variable magnification. FIG. 10 is a timing chart (part 2) when the PFGATE_N signal is asserted in the case of performing 1.5 times the variable magnification. FIG. 11 is a timing chart (No. 1) when a PFGATE_N signal is negated in the case of performing 1.5 times the variable magnification. FIG. 10 is a timing chart (No. 2) when the PFGATE_N signal is negated in the case of performing 1.5 times the variable magnification. It is a timing chart explaining the operation | movement which converts 2 pixels into 3 pixels in the main scanning direction. It is a block diagram which shows the structure of a 1.5 times density process part. It is a figure which shows a mode that a 1.5 times dense process part divides | segments an image into a 3x6 matrix and outputs a 2x2 image matrix. It is a figure which shows the content of the register referred when dividing an image into a 3x6 matrix from a 2x2 image matrix and outputting it. FIG. 10 is a diagram (part 1) illustrating an operation in which a main scanning line correction image generation unit generates a 3 × 6 line correction output image matrix from a 2 × 2 input image matrix. FIG. 10 is a diagram (part 2) illustrating the operation of the main scanning line correction image generation unit generating a 3 × 6 line correction output image matrix from a 2 × 2 input image matrix. It is a figure explaining the example of an image synthesis in the case of SCNT = 1 or 3. It is a figure explaining the example of an image composition in case of SCNT = 2. It is a flowchart explaining the processing operation of the whole density conversion part which mainly made the processing operation in a 1.5 times dense processing part. It is a block diagram which shows the detailed structure of the density conversion part in the 2nd Embodiment of this invention. It is a timing chart when the PFGATE_N signal is asserted in the case of performing 1.5 times higher magnification. FIG. 11 is a timing chart when the PFGATE_N signal is negated in the case of performing 1.5 times fine scaling. It is a figure explaining the process in which an image recognition part discriminate | determines the kind of image. It is a block diagram which shows a 1.5-times density process part detailed structure. It is a timing chart explaining the operation | movement which a pattern matrix production | generation part produces | generates a pattern matrix. It is a figure which shows a mode that a 1.5 times dense process part divides | segments an image into a 3x6 matrix and outputs a 2x2 image matrix. It is a figure which shows the content of the register referred when dividing an image into a 3x6 matrix from a 2x2 image matrix and outputting it. It is FIG. (1) explaining the correction | amendment operation | movement a between matrices. It is FIG. (2) explaining the correction | amendment operation | movement a between matrices. It is a figure explaining the correction | amendment operation | movement b between matrices. It is a figure which shows the content of the register referred in the case of the correction | amendment operation | movement b between matrices.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Reading part 101 Sensor 102 Image amplification circuit 103 AD conversion circuit 104 Shading correction circuit 105 Image processing circuit 106 Synchronization control circuit 107 Reading control circuit 108 Scanner drive circuit 200 Copying apparatus 300 Image information storage part 301 Image memory part 302 System control part 303 Printer driving device 400 Operation unit 500 Writing unit 502 Density conversion unit 503 LPH
504 Drive control circuit

Claims (13)

A light-emitting element array in which a plurality of light-emitting elements are arranged in one direction; and an image forming unit that forms an image of light emitted from the light-emitting element array on a photoconductor, the axial length of the photoconductor A plurality of short light emitting element array units are arranged in the main scanning direction, image data for one line is divided for each light emitting element array unit and transferred to each light emitting element array unit at a predetermined transfer speed X, and the light emitting elements In the image writing device that drives each light emitting element of the array unit,
Transfer of the image data to the light emitting element array unit in the sub-scanning direction is performed at a transfer speed mX that is m (m is a positive integer) times the transfer speed X, and binary image data with a pixel density Adpi is obtained. , {(2B + 1) / 2} (B is a positive integer) density conversion mode for density conversion and output, and when the density conversion mode is selected, binary image data of Adpi × Adpi Is stored in n (n is a positive integer) number of memories, and pattern recognition processing of image data is performed for each n × n matrix on the image data in the n memories while [mn ( 2B + 1) / 2] × [n (2B + 1) / 2] is converted into image data of [m (2B + 1) / 2] dpi × [(2B + 1) / 2] dpi, and simultaneously with this density conversion, Vertical lines appear at matrix joints in the main scanning direction In the image writing, an image with a corrected line width is simultaneously generated, the line width of the portion is corrected, and the sub-scanning direction is transferred to each light emitting element array unit as the transfer speed mX. apparatus.   When the density conversion mode is selected, the image writing device accumulates binary image data of Adpi × Adpi in two memories by two lines, and 2 × for the image data of the two memories. [2m (2B + 1) / 2] × [2 (2B + 1) / 2] is converted while performing pattern recognition processing of image data every two matrices, and [m (2B + 1) / 2] dpi × [(2B + 1) / 2] Converted to dpi image data, and simultaneously with this density conversion, an image with a corrected line width when a vertical line straddles the seam of the matrix in the main scanning direction is generated simultaneously, and the line width of that portion is corrected 2. The image writing apparatus according to claim 1, wherein the sub-scanning direction is transferred to each of the light emitting element array units at the transfer speed mX.   When the density conversion mode is selected, the image writing device transfers the image data to the light emitting element array unit in the sub-scanning direction at a transfer speed 2X that is twice the transfer speed X. The image writing apparatus according to claim 1 or 2.   4. The image writing apparatus according to claim 1, wherein when the density conversion mode is selected, the binary image data of 400 dpi × 400 dpi is subjected to density conversion to {(2B + 1) / 2} times. The image writing apparatus described.   5. The image writing apparatus according to claim 1, wherein when the density conversion mode is selected, the image writing apparatus converts the density of the image data to a density of {(2B + 1) / 2} = 1.5 times. Any one of the image writing apparatuses.   The image writing apparatus transfers the light emitting elements a plurality of times during one main scanning line while transferring the sub scanning direction to each light emitting element array unit at a transfer speed mX which is m times the transfer speed X. The image writing apparatus according to claim 1, wherein the image writing apparatus is an image writing apparatus. An image writing apparatus for forming an electrostatic image on a photosensitive member using a light emitting element array unit, wherein image data is transferred to the light emitting element array unit at a predetermined transfer speed X, and each light emitting element of the light emitting element array unit In an image writing device for driving
Transfer of the image data to the light emitting element array unit in the sub-scanning direction is performed at a transfer speed mX that is m (m is a positive integer) times the transfer speed X, and binary image data with a pixel density Adpi is obtained. , {(2B + 1) / 2} (B is a positive integer) density conversion mode for density conversion and output, and when the density conversion mode is selected, binary image data of Adpi × Adpi Are stored in k lines (k is a positive integer) by k lines, and the image data pattern for each n × n matrix for image data from n of the k memory image data. In order to refer to the joints of each n × n matrix while performing the recognition process, a matrix larger than n × n is generated, and the image degradation occurring at the matrix seam is corrected by referring to the matrix. mn (2B + 1) / ] × [n (2B + 1) / 2] matrix, converted into [m (2B + 1) / 2] Adpi × [(2B + 1) / 2] Api image data, and the sub-scanning direction as the transfer speed mX An image writing apparatus that transfers to each of the light emitting element array units.   When the density conversion mode is selected, the image writing apparatus accumulates binary image data of Adip × Adpi in k (k is a positive integer) memories k by line, and stores the k memory in the k memories. A matrix n × 3n matrix that takes n × n matrix patterns before and after the main scanning direction into consideration while performing pattern recognition processing of the image data for each n × n matrix for n image data. Reference is made at the same time to correct the deterioration of the image that occurs at the joint of the matrix, and the matrix is converted into [mn (2B + 1) / 2] × [n (2B + 1) / 2] matrix, and [m (2B + 1) / 2] Adi ×. 8. The image data according to claim 7, wherein the image data is converted into [(2B + 1) / 2] Api image data and transferred to each of the light emitting element array units with the sub-scanning direction as the transfer speed mX. Writing device.   When the density conversion mode is selected, the image writing apparatus accumulates binary image data of Adip × Adpi in k (k is a positive integer) memories k by line, and stores the k memory in the k memories. A matrix n × 3n matrix that takes n × n matrix patterns before and after the main scanning direction into consideration while performing pattern recognition processing of the image data for each n × n matrix for n image data. Simultaneously referencing and correcting image degradation that occurs at matrix joints using a correction pattern that can be arbitrarily set, and converting the matrix into a [mn (2B + 1) / 2] × [n (2B + 1) / 2] matrix, [M (2B + 1) / 2] Adpi × [(2B + 1) / 2] Api image data is converted and transferred to each light emitting element array unit with the sub-scanning direction as the transfer speed mX. Image writing apparatus according to claim 7, wherein Rukoto.   When the density conversion mode is selected, the image writing apparatus accumulates binary image data of Adip × Adpi in k (k is a positive integer) memories k by line, and stores the k memory in the k memories. Among the n pieces of image data, pattern recognition processing of the image data is performed for each n × n matrix, and one line in the peripheral sub-scanning direction and two lines before and after in the main scanning direction with respect to this matrix. The increased (n + 1) × (n + 2) matrix is also referred to at the same time, and image degradation occurring at the matrix seam is corrected, and converted into a [mn (2B + 1) / 2] × [n (2B + 1) / 2] matrix. To [m (2B + 1) / 2] Api × [(2B + 1) / 2] Api image data, and transfer to the respective light emitting element array units with the sub-scanning direction as the transfer speed mX. 8. The image writing apparatus according to claim 7, wherein   When the density conversion mode is selected, the image writing apparatus accumulates binary image data of Adip × Adpi in k (k is a positive integer) memories k by line, and stores the k memory in the k memories. Among the n pieces of image data, pattern recognition processing of the image data is performed for each n × n matrix, and one line in the peripheral sub-scanning direction and two lines before and after in the main scanning direction with respect to this matrix. The increased (n + 1) × (n + 2) matrix is also referred to at the same time, and the deterioration of the image occurring at the matrix joint is corrected using a correction pattern that can be arbitrarily set, and [mn (2B + 1) / 2] × [n (2B + 1) / 2] matrix is converted into [m (2B + 1) / 2] Adpi × [(2B + 1) / 2] Adpi image data, and the sub-scanning direction is set at the transfer speed mX. 8. The image writing apparatus according to claim 7, wherein the image writing apparatus transfers to each light emitting element array unit.   When the density conversion mode is selected, the image writing device recognizes what the image to be converted is, selects a matrix seam correction operation according to the image, and incorporates the image writing device. 12. The image writing apparatus according to claim 7, wherein a correction operation of a matrix seam is selected for each model.   The image writing unit irradiates light onto the photoconductor to form an electrostatic latent image on the photoconductor, and finally transfers the developer image obtained by developing the electrostatic latent image with a developer onto a sheet recording medium. In the image forming apparatus for forming an image, the image writing apparatus according to claim 1 is used as the image writing unit.