JP2010120346A - Image forming apparatus and image formation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which suppresses degradation of image quality when converting image data, and to provide an image formation method. <P>SOLUTION: The image forming apparatus includes: an exposure head which has an optical image forming system and light emitting elements arranged in a first direction where an image is formed by the optical image forming system; and an image processing part which develops image data on the basis of information from the optical image forming system or the light emitting elements, whereby the degradation of latent image quality is compensated. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus and an image forming method configured to prevent image quality degradation when converting image data.

  In an electrophotographic image forming apparatus, a latent image is formed on an image carrier (photoreceptor) using an exposure head in which two or more light emitting elements and an imaging optical system for imaging light from the light emitting elements are arranged. Those of the construction to be formed are known. As this imaging optical system, a technique using a lens (ML) having a negative optical magnification has been developed. Japanese Patent Application Laid-Open No. 2004-133867 discloses an image forming apparatus that corrects the light amount of a light emitting element according to the type of screen during screen processing.

JP 2008-018665 A

  In an image forming apparatus using a lens array (MLA) composed of ML, the alignment of light emitting elements may occur due to the joining of ML. Thus, in a state where there is a distortion of the light emitting elements, if the processing is not performed in the light emitting element coordinate system in consideration of the distortion, the image is also distorted and the image quality is deteriorated. In Patent Document 1, data is converted in the order of rendering (data development) → color conversion → screen processing. For this reason, there is a problem in that data development cannot be performed in the light emitting element coordinate system in printers having different light emitting elements for different colors.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus and an image forming method that prevent deterioration in image quality when converting image data. .

The image forming apparatus of the present invention that achieves the above object provides:
An exposure head having an imaging optical system and a light emitting element disposed in a first direction imaged by the imaging optical system;
A latent image carrier on which a latent image is formed by the exposure head;
A control unit for converting image data based on information of the imaging optical system or the light emitting element;
It is provided with.

  In the image forming apparatus of the present invention, the control unit converts the first coordinate system representing the image data into a second coordinate system based on information of the imaging optical system or the light emitting element.

In the image forming apparatus of the present invention, the control unit includes a color conversion processing unit,
After the color conversion processing of the image data by the color conversion processing unit, the color-converted image data is converted into the second coordinate system.

  In the image forming apparatus of the present invention, the information on the light emitting element is position information on the light emitting element arranged in the first direction.

  In the image forming apparatus of the present invention, the imaging optical system is provided with a first lens array and a second lens array in the first direction, and the information on the imaging optical system includes the information This is the distance between the light emitting elements at the joint between the first lens array and the second lens array.

In the image forming apparatus of the present invention, the control unit includes a screen processing unit,
After the screen processing of the image data by the screen processing unit, the image data screen-processed by the screen processing unit is converted into the second coordinate system.

  In the image forming apparatus of the present invention, the imaging optical system has a negative optical magnification.

The image forming method of the present invention includes an imaging optical system and an imaging optical system of an exposure head having a light emitting element arranged in a first direction that is imaged on a latent image carrier by the imaging optical system. Obtaining information of the light emitting element;
A step of color-converting image data;
Transforming the color-converted image data into a second coordinate system by converting a first coordinate system expressing the image data based on information of the imaging optical system or the light emitting element; It is characterized by having.

  An embodiment of the present invention will be described. 11 and 12 are explanatory diagrams showing the prerequisite technology of the present invention. FIG. 11 shows an arrangement relationship between a lens (ML) having a negative optical magnification and a light emitting element (dot). In FIG. 11, two or more light emitting elements 2 are arranged in ML4 in the axial direction (X direction, first direction) of the photoconductor and the rotation direction (Y direction, second direction) of the photoconductor. These light emitting elements form a latent image on the photoreceptor. In the embodiment of the present invention, the X direction may be described as a first direction, and the Y direction may be described as a second direction.

  For the sake of convenience, the light emitting elements 2 are numbered “1 to N”. The light emitting element row 3a in the first column in the Y direction has “2, 4,... N” light emitting elements arranged from the left side to the right side in the X direction. In the light emitting element row 3b arranged in the second column in the Y direction, 1, 3,. Here, two or more lenses (ML) 4 are arranged in the X direction to constitute a microlens array (MLA). In addition, a lens array (MLA) can be configured by arranging two or more lenses (ML) in the X direction and the Y direction. Here, the light emitting element “2, N” is a light emitting element at an end portion in the X direction of the micro lens (ML).

  FIG. 12 is an explanatory diagram of an exposure head using a lens array (MLA). When the number of light emitting elements (number of dots) for forming a one-line latent image in the axial direction of the photoconductor increases, a long MLA (lens array) is required in the axial direction of the photoconductor. In such a case, it is possible to form a long MLA head by connecting a plurality of MLAs having a certain length. FIG. 12 (a) shows a schematic overall configuration, and FIG. 12 (b) schematically shows a part of FIG. 12 (a). FIG. 12A shows a long MLA head (exposure head) 10, and 5 n is a part of the long MLA head. FIG.12 (b) is a figure which expands and shows 5n of MLA.

  In FIG. 12B, the exposure head has two or more light emitting elements 2 arranged on a substrate 1. Reference numeral 3 denotes a light emitting element group composed of two or more light emitting elements arranged on one lens 4a. In the light emitting element group 3, two or more light emitting elements are arranged in the axial direction X of the photoreceptor and the rotation direction Y of the photoreceptor. Reference numeral 4 denotes a lens (ML), and two or more lenses are arranged in the axial direction (main scanning direction) X of the photoconductor and the rotation direction (sub-scanning direction) Y of the photoconductor to constitute a lens array (MLA). . L of the lens 4a is the width of one row of light emitting elements arranged in the X direction within one lens, dp is the distance between the light emitting elements (dots), and P is the distance between the adjacent lenses 4a and 4b in the Y direction. The distance between the first dots in the X direction is shown.

  As shown in FIG. 12A, when a plurality of MLAs are connected in the axial direction of the photosensitive member, variations between the pitches of the connecting portions of the MLAs and registration deviation (positional deviation) become problems. Due to such a problem, a physical latent image spot may increase on the photoconductor. This is a case where the number of redundant latent image spots is increased by increasing the pitch between MLAs. In addition, when an MLA is constituted by a plurality of MLs, ML pitch deviation may occur in the main scanning direction. Due to the configuration of the MLA, even if it is adjacent as a pixel on the photoconductor, it is not necessarily adjacent as a light emitting element in the MLA, and may have a distance between light emitting elements or a distance between MLs. In such a case, unevenness in the amount of light in the MLA is caused.

As an optical printer using a line head, there are an electrophotographic printer using an LED head and an electrophotographic printer using a liquid crystal line head.
These printers convert print data described in units of pages into optical write data and print. Particularly in the case of color, data described in various color coordinate systems such as RGB is converted into CMYK that can be printed by a printer. Further, halftone processing is performed in order to express shading, and the image is expressed by halftone dots of CMYK.

  Light emitted from the light emitting element is imaged on the photosensitive member by the optical system of the exposure head. Since the light emitting elements are arranged at substantially equal intervals, the images on the photoconductor are also at substantially equal intervals. This can be viewed as a coordinate system. That is, in the main scanning direction (X direction: first direction), a lattice is engraved at intervals of the light emitting elements. Further, in the sub-scanning direction (Y direction: second direction), a grid is engraved at a predetermined feeding interval of the photosensitive member. Such a coordinate system is defined as a light emitting element coordinate system.

  On the other hand, a document (image data) created by a word processor or DTP software is composed of characters, figures, photographs, etc., and these may be arranged at a predetermined size at a predetermined position on the final output paper. Is intended. In order to define a predetermined position and size on the paper, a document-specific coordinate system is used. This is defined as the document coordinate system.

  When printing with a printer, it consists of Cartesian coordinate system unique to the printer based on the design spacing of light emitting elements (300dpi, 600dpi, etc.), that is, it consists of orthogonal axes, and the distance distance on the coordinate is equal at any position of the coordinate This coordinate system is converted from the document coordinate system to this coordinate system, and finally sent to the exposure head as image data. This coordinate system is defined as a logical coordinate system.

  Conventionally, this logical coordinate system is seen in the same manner as the light emitting element coordinate system, and data developed in the logical coordinate system is sent to the exposure head as it is, and a latent image is written on the photosensitive member in the light emitting element coordinate system. However, the light emitting element coordinate system is far from the Cartesian coordinate system, as will be described later. For this reason, even though the logical coordinate system is intended to be a Cartesian coordinate system, characters, figures, and photographs are arranged in a distorted coordinate system when printing on paper.

  Although the light emitting elements are arranged at substantially equal intervals, for example, in the case of LEDs, the intervals are disturbed at the joint between the chips due to the accuracy of attaching the chips. In addition, when the chip is installed to be inclined with respect to the axial direction of the photosensitive member, the pitch of the light emitting element image on the photosensitive member becomes narrower than the pitch of the light emitting element. Furthermore, since the tip inclination method varies from chip to chip, the pitch narrowing method varies from chip to chip. That is, the interval between the coordinates in the X direction is narrower than the interval in the printer coordinate system, and further, the interval changes at the joint between the chips, and is different at the portions corresponding to different chips. This is far from a Cartesian coordinate system that assumes equal spacing. Such a situation is the same in a system using an MLA type exposure head, and the light emitting element coordinate interval is disturbed at the joint of the MLA split lens.

  FIG. 3 is a reference example showing such a problem. 3A shows a case where there is no distortion in the array 3X of light emitting elements, FIG. 3C shows a case where there is a distortion in the array 3Y of light emitting elements, and FIG. ing. Further, in the case where the page data 6a to 6c in FIGS. 3B, 3D, and 3F specify that the lower portions 8a to 8c are to be filled from the curves 7a to 7c, the expansion is performed. An example is shown. It can be said that the curves 7a to 7c indicate the boundaries of the processing of the image data (whether it is painted or white). Conventionally, the image data is developed ignoring the distortion of the arrangement of the light emitting elements. Therefore, the image data is developed in the same manner in the logical coordinate system regardless of whether or not the light emitting elements are distorted. In the case of FIG. 3A with no distortion, it is printed correctly, but in the case of FIG. 3C and FIG. 3E with distortion, it is greatly deviated from the originally designated curves 7b and 7c. The area that was originally designated as a white background has been filled.

  The present invention solves such problems. Specifically, the image data is converted from the document coordinate system to the light emitting element coordinate system, and data for driving the exposure head is generated so that an image with less distortion can be printed. FIG. 4 is an example of a figure developed by the present invention. 4A and 4B show the page data 6d and 6e of the light emitting element coordinate system having different distortion methods. As described above, FIG. 4 shows how a graphic defined in the document coordinate system is developed in a light emitting element coordinate system having different distortion methods.

  In FIGS. 4A and 4B, 6d and 6e are page data, 7d and 7e are curves indicating the boundaries of processing of image data, and 8d and 8e are areas designated to be painted black. As described above, since the distortion of the arrangement of the light emitting elements is different in FIGS. 4A and 4B, the same graphic data is developed in different shapes. For example, in the rightmost column 6u in FIG. 4A, the upper two images are off (white), whereas in the rightmost column 6v in FIG. 4B, only the upper one image is displayed. Is off.

  FIG. 5 and FIG. 6 are explanatory diagrams in which figures developed by the prior art and the present invention are compared with actual exposure spot shapes. FIG. 5 shows a conventional example, and FIG. 6 shows the present invention. 5 (a) and 5 (b) correspond to FIGS. 3 (d) and 3 (f), respectively. 9b and 9c are actual exposure spot shapes. 6 (a) and 6 (b) correspond to FIGS. 4 (d) and 4 (f), respectively. 9d and 9e are actual exposure spot shapes. 5 and 6 are compared, the image according to the present invention is more faithful to the original data than the image of the conventional example, and further, there is less variation between apparatuses.

FIG. 1 is a block diagram showing the flow of processing of the present invention. The control unit 70 includes a color conversion unit 72 of a color designation unit that converts the graphic data 71 into a color coordinate system,
Color conversion means 74 for pixel data for color conversion of the bitmap image data 73, conversion means 75C to 75K for CMYK halftone dots, conversion means 76C to 76K for CMYK light emitting element coordinates, and light emitting element coordinate grids for CMYK ON / OFF data (ON / OFF determining means) 77C to 77K are provided.

  Next, the process of FIG. 1 will be described. The graphic data 71 describing the page is described by coordinate data in the document coordinate system. For example, it is described in a format such as “draw a straight line from coordinates (x0, y0) to (x1, y1) with color (r0, g0, b0)”. As described above, the graphic data 71 includes coordinate data that defines the shape of the graphic and a color designation unit that defines the color of the graphic. The color designation of the graphic data is generally designated in the RGB color coordinate system, but in order to print with a printer, it must be converted into the CMYK color coordinate system by the color conversion means 72.

  Further, the graphic data describing the page includes data 73 represented by a bitmap of a certain resolution like a photograph. For example, “Draw an image defined in the following RGB color coordinate system with coordinates (x2, y2) as the upper left corner. The resolution is 150 dpi, the width is 200 pixels, the data is (100,100,0), (100,101 , 0), ... ". Also in this case, since the data itself is defined in the RGB standard system, the color conversion means 74 must perform color conversion to CMYK.

  In the present invention, the color designation of graphic data and the pixel data constituting the bitmap image are converted to CMYK of the printer. After color conversion, data is collected for each color of CMYK, which is called color separation. The data decomposed into C is converted into a large number of halftone dots by a C screen (halftone dot conversion means 75C) that performs halftone processing on C. Here, a halftone dot figure describes the shape of a halftone dot in the document coordinate system. For example, one halftone dot is “a circular arc with a center position (x3, y3) radius r3 and a start angle of 55 degrees and an end angle of 340 degrees. And “the part surrounded by the strings”.

  The data converted into halftone dots by color is converted by the conversion means 76C to 76K into the light emitting element coordinate system associated with the line head in charge of each color. The halftone dot figure that was represented by the coordinate values in the document coordinate system so far is, for example, “Center position (X3, Y3) radius R3, start angle 50 degrees, end angle 338 degrees arc and the inside of the string” Converted to coordinate values in the element coordinate system.

Whether or not to turn on the light emitting element is determined based on whether or not the light emitting element coordinate grid associated with the light emitting element is included in the dot pattern region described in the light emitting element coordinate system. If the grid is included in the halftone dot region, the corresponding light emitting element is turned on to form an image of that color.
FIG. 7 is an explanatory diagram of a light emitting element coordinate grid. 7A shows an array 3Y of distorted light emitting elements corresponding to FIG. 3C, and FIG. 7B shows an array 3Z of distorted light emitting elements corresponding to FIG. Show. Here, the light emitting element coordinate lattices 11a and 11b are rectangular lattices on coordinates corresponding to the light emitting elements as shown in FIGS. 7B and 7D. Based on the data of the light emitting element coordinate grids 11a and 11b, the on / off determining means 77C to 77K shown in FIG.

  In the ideal state, the light-emitting element coordinate grid is a grid corresponding to how the light-emitting elements are actually distorted, for example, (1,1) to (15,1). ing. The grid is formed in the Y direction (rotating direction of the photoconductor) in time increments in which write data is sent in correspondence with the image feed. In the example of FIG. 7B, the distortion 3Y of the arrangement of the light emitting elements is large, that is, the positional variation of the light emitting elements is larger than the feed pitch in the Y direction. For this reason, a step is generated in the lattice, and the lattice of (6, 1) is not adjacent to (5, 1) but rather adjacent to (5, 2) on the output image. On the other hand, in the example of FIG. 7D, the distortion 3Z of the arrangement of the light emitting elements is small, and there is no significant step in the light emitting element coordinate lattice 11b.

  In FIG. 1, on / off of each light emitting element coordinate grid is determined by the halftone dot graphic data converted into the light emitting element coordinates, and the light emitting elements are driven in accordance therewith to form a halftone dot image. As described above, in the embodiment of FIG. 1, since the image data is converted into the light emitting element coordinate system after the color separation, even if the light emitting element coordinate system is different for each color as in the case of a tandem type printer, Data development that is most suitable for the color of the can.

  In the tandem type printer, since the exposure heads for forming CMYK monochrome images are separately provided, the light emitting element coordinate systems are also different for each CMYK. Further, since the image data is converted into a halftone figure for each color in the document coordinate system after color separation, the converted data does not depend on individual differences of printers or changes with time. For this reason, it is possible to cope with flexible printing in which this data can be sent to another printer as it is for printing, or stored and printed later.

  FIG. 2 is a block diagram showing the flow of data in another embodiment of the present invention. In the control means 80 of FIG. 2, the same reference numerals are assigned to the same processing means as in FIG. In the example of FIG. 2, contone data setting means 81C to 81K and CMYK screen processing means 82C to 82K are provided for each light emitting element coordinate grid. The process of FIG. 2 differs from the embodiment of FIG. 1 in that data is converted into the light emitting element coordinate system prior to the halftone process. Data that has been color-separated and described in the document coordinate system is converted into a light-emitting element coordinate system for each color of CMYK, and data of the light-emitting element coordinate grid is determined. In this embodiment, since the halftone process is not performed, the data of the light emitting element coordinate grid remains as data with gradation (contone data). In order to form an image with a printer, the contone data is subjected to screen processing, converted into information on whether to turn on or off the light emitting element, and sent to the exposure head.

  In this halftone process, a threshold table can be used as a screen table. Since the contone data to be processed is described in the light emitting element coordinate system, a desired halftone dot shape cannot be obtained by processing with a threshold table in the document coordinate system or logical coordinate system. In this embodiment, a desired halftone dot shape can be more accurately reproduced by defining the threshold value table in the light emitting element coordinate system.

  As described above, in the embodiment of FIG. 2 as well, since the color conversion is performed after the color conversion, the optimum data development can be performed even if the light emitting element coordinate system is different for each color. Further, since the halftone process is performed on the light-emitting element coordinate system contone data using the light-emitting element coordinate system threshold table, the halftone process can be performed at high speed with a relatively simple circuit or program.

  FIG. 8 is an explanatory diagram showing an example of a threshold table for halftone processing in the light emitting element coordinate system. FIG. 8A shows a screen table 12a of the logical coordinate system. The numerical values in the grid of the screen table 12a are threshold values to be compared with the gradation values of the image data, and form a threshold value table. A portion 13 surrounded by a bold line is an output data forming portion of the screen table 12a. In the lattice of the logical coordinate system, the X direction and the Y direction are orthogonal as shown in FIG. However, when there is distortion of the light emitting elements, the lattice of the light emitting element coordinate system has a step 12X as described with reference to FIGS. 3D and 3F. The screen table 12b in FIG. 8B is obtained by superimposing the logical coordinate system screen table 12a and the light emitting element coordinate system grid 12X.

  FIG. 8C shows the screen table 12c of the light emitting element coordinate system. 12X corresponds to the step of the light emitting element coordinate system described with reference to FIG. Thus, when there is distortion of the light emitting elements, it is necessary to correct the threshold value of the light emitting element coordinate system. The threshold value of the screen table 12c of the light emitting element coordinate system is modified from the threshold value of the screen table 12a of the logical coordinate system described with reference to FIG. For example, the threshold values at the left end in the X direction and the upper end in the Y direction are “30” in FIG. 8A and “46” in FIG.

  As described above, the example in which the logical coordinate system is converted into the light emitting element coordinate system and developed based on the distortion information of the arrangement of the light emitting elements has been described. The embodiment of the present invention can also be applied to an example using the ML coordinate system of the imaging optical system. In this case, the pitch between the light emitting elements at the joint of the lens array becomes information, and the logical coordinate system of the original image data is converted to the ML coordinate system.

  FIG. 9 is a block diagram showing an embodiment of the present invention. In FIG. 10, reference numeral 30 denotes an image forming apparatus (printer) having a main controller (MC) 31, an engine controller (EC) 33, a head controller (HC) 34, and an engine unit (EG) 36. In addition, an image formation command is output to a main controller (MC) 31 from a print server such as an external PC (not shown).

  The main controller (MC) 31 is provided with a memory 32a for storing solid information such as MLA redundant dots, a color conversion module 39a, and a table memory 39b having table data for the color conversion module. A screen processing module 39c, a table memory 39d having table data for the screen processing module, and a page memory 39e for storing print image data are provided. The memory 32a also stores data from the engine controller (EC) 33 and the head controller (HC) 34.

  The table memory 39d stores the threshold table of the logical coordinate system and the threshold table of the light emitting element coordinate system described in FIG. The distortion of the arrangement of the light emitting elements may be measured by measuring means such as an optical sensor, and the measurement result may be stored in the memory 32a of the main controller (MC) 31, for example. Processing such as coordinate conversion and light-emitting element on / off data creation described with reference to FIGS. 1 and 2 is executed by the CPU of the main controller (MC) 31.

  The head controller (HC) 34 is provided with a head control module 35. The head control module 35 transmits print data to the four color MLA heads 37C, 37M, 37Y, and 37K of C, M, Y, and K. The engine controller (EC) 33 controls the head control module 35 and the engine unit (EG) 36. The engine unit (EG) 36 is provided with an image scan and density measurement unit 36 a that scans an image and measures density.

  In FIG. 9, a print instruction is transmitted from the main controller (MC) 31 to the engine controller (EC) 33, and a print pattern is created by the main controller (MC) 31 and stored in the page memory 39e ( (Video DATA) is transmitted to the head controller (HC) 34.

  The engine controller (EC) 33 controls printing by the engine unit (EG) 36, and the head controller (HC) 34 transmits print data to the MLA heads 37C to 37K. After printing, the main controller (MC) 31 is notified of the data obtained by scanning the image by the engine unit 36 and the result of the image density measurement. Image scanning and image density measurement may be performed by another apparatus of the image forming unit 30, for example, a head controller (HC) 34.

  The main controller (MC) 31 determines whether the intended print result is obtained from the received scan data and density measurement data, and performs feedback control to the image processing unit 30. The feedback to the image processing unit 30 is to change the color conversion table or the color conversion parameter value, or to change the screen table or the screen processing parameter value.

  It is assumed that four lines of images from the first line to the fourth line are printed in the rotation direction of the photoconductor in the print image formed on the photoconductor. In this case, the density distribution of the print image that scans the print image in which the MLA is turned on for each row is measured, and the dot position of the print image is measured. Next, the measurement result of the dot position of the printed image is reflected on the screen table. This process includes a change of the color conversion parameter value, a change of the screen table or the parameter value of the screen process.

  The above processing is repeated for the number of MLA rows. A screen table is created by a device having such a function. In the configuration of FIG. 9, the main controller (MC) 31 is provided with a memory 32 a that stores individual information such as whether or not spots are added at the MLA connection portion corresponding to each color. The memory 32a for storing such MLA individual information is provided in all the exposure heads.

  In the embodiment of the present invention, a tandem color printer that exposes four photoconductors with four line heads, simultaneously forms four color images, and transfers them onto one endless intermediate transfer belt (intermediate transfer medium). The target is a line head used in (image forming apparatus). FIG. 10 is a longitudinal side view showing an example of a tandem image forming apparatus using an organic EL element as a light emitting element. In this image forming apparatus, four line heads 101K, 101C, 101M, and 101Y having the same configuration are exposed to four corresponding photosensitive members (image carriers) 41K, 41C, 41M, and 41Y having the same configuration. They are arranged at each position.

  As shown in FIG. 10, this image forming apparatus is provided with a driving roller 51, a driven roller 52, and a tension roller 53, and is an intermediate transfer belt that is circulated and driven in the direction indicated by the arrow (counterclockwise) by the tension roller 53. 50. Photosensitive members 41K, 41C, 41M, and 41Y are arranged at predetermined intervals with respect to the intermediate transfer belt 50. K, C, M, and Y added after the reference sign mean black, cyan, magenta, and yellow, respectively. The photoconductors 41 </ b> K to 41 </ b> Y are driven to rotate in the direction indicated by the arrow (clockwise) in synchronization with the driving of the intermediate transfer belt 50. Around each photoconductor 41 (K, C, M, Y), a charging unit 42 (K, C, M, Y) and an exposure head 101 (K, C, M, Y) are provided.

  Further, a developing device 44 (K, C, M, Y) that applies a toner as a developer to the electrostatic latent image formed by the exposure head 101 (K, C, M, Y) to form a visible image; The primary transfer roller 45 (K, C, M, Y) and the cleaning device 46 (K, C, M, Y) are included. The emission energy peak wavelength of each line head 101 (K, C, M, Y) and the sensitivity peak wavelength of the photoconductor 41 (K, C, M, Y) are set to substantially coincide.

  The black, cyan, magenta, and yellow toner images formed by the four-color single-color toner image forming station are intermediated by the primary transfer bias applied to the primary transfer roller 45 (K, C, M, Y). The toner image, which is sequentially primary transferred onto the transfer belt 50 and sequentially superposed on the intermediate transfer belt 50 to become a full color, is secondarily transferred to a recording medium P such as paper by a secondary transfer roller 66, and serves as a fixing unit. The toner is fixed on the recording medium P by passing through the fixing roller pair 61, and is discharged onto a paper discharge tray 68 formed in the upper part of the apparatus by a paper discharge roller pair 62.

  63 is a paper feed cassette in which a large number of recording media P are stacked and held, 64 is a pickup roller for feeding the recording media P from the paper feed cassette 63 one by one, and 67 is a secondary transfer portion of the secondary transfer roller 66. A pair of gate rollers for defining the supply timing of the recording medium P to the medium, 66 is a secondary transfer roller as a secondary transfer means for forming a secondary transfer portion with the intermediate transfer belt 50, and 69 is an intermediate after the secondary transfer. This is a cleaning blade that removes toner remaining on the surface of the transfer belt 50.

  As described above, the image forming apparatus and the image forming method in which the deterioration of the image quality of the present invention is suppressed have been described based on the principle and the embodiments. However, the present invention is not limited to these embodiments and can be variously modified.

It is a block diagram which shows embodiment of this invention. It is a block diagram which shows embodiment of this invention. It is explanatory drawing which shows the reference example of this invention. It is explanatory drawing which shows embodiment of this invention. It is explanatory drawing which shows the reference example of this invention. It is explanatory drawing which shows embodiment of this invention. It is explanatory drawing which shows embodiment of this invention. It is explanatory drawing which shows embodiment of this invention. It is a block diagram which shows embodiment of this invention. 1 is a schematic cross-sectional view showing an overall configuration of an embodiment of an image forming apparatus using an electrophotographic process of the present invention. It is explanatory drawing which shows the premise technique of this invention. It is explanatory drawing which shows the premise technique of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2 ... Light emitting element, 3 ... Light emitting element group (spot group), 3a, 3b ... Light emitting element row, 4 ... Lens (ML), 5n ... Lens array ( MLA), 12a ... screen table of logical coordinate system, 12b ... screen table of light emitting element coordinate system, 30 ... image forming unit (printer), 31 ... main controller (MC), 33 ... Engine controller (EC) 34 ... Head controller (HC) 35 ... Head control module 36 ... Engine part (EG) 37C, 37M, 37Y, 37K ... MLA head 39 ..Image processing unit, 39a, color conversion module, 39c, screen processing module, 39b, 39d, table memory, 39e, page memory 41 (Y, M, C, K): photoconductor, 50: intermediate transfer medium, 101 (Y, M, C, K): exposure head, P: recording medium, Y, M , C, K ... Image forming station

Claims (8)

An exposure head having an imaging optical system and a light emitting element disposed in a first direction imaged by the imaging optical system;
A latent image carrier on which a latent image is formed by the exposure head;
A control unit for converting image data based on information of the imaging optical system or the light emitting element;
An image forming apparatus comprising: The image forming apparatus according to claim 1, wherein the control unit converts a first coordinate system expressing the image data into a second coordinate system based on information of the imaging optical system or the light emitting element. The control unit includes a color conversion processing unit,
The image forming apparatus according to claim 1, wherein the image data is subjected to color conversion processing by the color conversion processing unit, and then the color-converted image data is converted to the second coordinate system. The image forming apparatus according to claim 1, wherein the information on the light emitting element is position information on the light emitting element disposed in the first direction. The imaging optical system is provided with a first lens array and a second lens array in the first direction, and information on the imaging optical system includes the first lens array and the second lens array. The image forming apparatus according to any one of claims 1 to 3, wherein the distance between the light emitting elements at a joint portion with the lens array. The control unit has a screen processing unit,
6. The image processing apparatus according to claim 2, wherein after the screen processing of the image data is performed by the screen processing unit, the image data screen-processed by the screen processing unit is converted into the second coordinate system. Image forming apparatus.
The image forming apparatus according to claim 1, wherein the imaging optical system has a negative optical magnification. Information on the imaging optical system or the light emitting element of an exposure head having an imaging optical system and a light emitting element disposed in a first direction imaged on a latent image carrier by the imaging optical system is acquired. Process,
A step of color-converting image data;
Transforming the color-converted image data into a second coordinate system by converting a first coordinate system expressing the image data based on information of the imaging optical system or the light emitting element; ,
An image forming method comprising:

Images