JP2007216540A - Multiplex image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multiplex image forming apparatus preventing degradation in picture quality without increasing cost by reducing the step difference of a toner image, in a joint part of a datum with skew corrected, when forming an image with an optical recording element. <P>SOLUTION: An exposing means is equipped with a light emitting element array constituted of a plurality of connected element groups comprising a specified number of light emitting elements which are arranged in one specified direction according to a specified regulation, and a light emitting control means for controlling the light emitting elements 62a1 to 62n8 to emit light in the respective element groups 62a to 62n of the light emitting element array in a first light-emitting order. The light emitting control means includes a light-emitting order changing function to change the first light-emitting order of the light-emitting elements 62a1 to 62n8 in a part of the element groups in the element 62a to 62n groups to the second light emitting order so as to smooth the joint part of the datum, when the datum skew corrected has the joint part. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a multiple image forming apparatus capable of forming a composite image by superimposing image information on a transfer material using an electrophotographic system or the like.

  Conventionally, in an image forming apparatus adopting an electrophotographic method, an electrophotographic photosensitive member as an image carrier is charged by a charger, and light is irradiated on the photosensitive member according to image information to form a latent image. An image is formed by transferring a toner image developed by developing the latent image with a developing device to a transfer material such as a sheet material.

  On the other hand, in recent years, along with the colorization of images, a plurality of photoconductors that perform each of these image forming processes are provided, and each color image of a cyan image, a magenta image, a yellow image, and preferably a black image is formed on each photoconductor. In addition, a tandem multiple image forming apparatus that forms a full color image by transferring each color image on a transfer material in an overlapping manner at a transfer position of each photoconductor has been proposed. Such a tandem multiple image forming apparatus has an image forming unit for each color, which is advantageous for speeding up.

  However, there is a problem in how well the registration (registration) of images formed by different image forming units is performed. This is because the shift in the image forming positions of the four colors transferred to the transfer material finally appears as a color shift or a change in color tone.

  FIG. 20 is a diagram showing a schematic configuration of a conventional multiple image forming apparatus using four photosensitive drums. In FIG. 20, 101a to 101d are photosensitive drums, 102a to 102d are charging means, 103K, 103C, 103M and 103Y are exposure means, 104a to 104d are developing means, 105a to 105d are transfer means, and 106a to 106d are cleaning means. , 107 is an intermediate transfer belt, 108 is a sheet feeding roller, 109 is a sheet material, 110 is a sheet feeding table, 111 is a sheet material transfer roller, 112 is a fixing unit, 113 is a color misregistration detecting unit, and Pa is a first image. A forming station, Pb is a second image forming station, Pc is a third image forming station, and Pd is a fourth image forming station. In this multiple image forming apparatus, the first image forming station Pa is a place where a black (K) image is formed, and the second image forming station Pb is a place where a cyan (C) image is formed, and a third image forming station Pa is formed. The image forming station Pc is where a magenta (M) image is formed, and the fourth image forming station Pd is where a yellow (Y) image is formed.

  In such a multiple image forming apparatus, first, a yellow component color latent image of image information is formed on the photosensitive drum 101d by a known electrophotographic process means of the charging means 102d and exposure means 103d of the fourth image forming station Pd. Then, the latent image is visualized as a yellow toner image by the developer having yellow toner by the developing unit 104d, and the yellow toner image is transferred to the intermediate transfer belt 107 by the transfer unit 105d.

  On the other hand, while the yellow toner image is being transferred to the intermediate transfer belt 107, a latent image having a magenta component color is formed at the third image forming station Pc as in the case of the fourth image forming station Pd. Subsequently, a magenta toner image by magenta toner is obtained by the developing unit 104c, and the magenta toner image is transferred to the intermediate transfer belt 107, which has been transferred at the fourth image forming station Pd, by the transfer unit 105c of the third image forming station Pc. And is superimposed on the yellow toner image.

  Thereafter, the cyan toner image and the black toner image are formed in the same manner in the second and first image forming stations Pb and Pa, respectively, and the superposition of the four color toner images on the intermediate transfer belt 107 is completed. Then, after the four-color toner images formed on the intermediate transfer belt 107 by the sheet material transfer roller 111 are collectively transferred onto the sheet material 109 such as paper fed from the paper feed table 110 by the paper feed roller 108. The sheet is conveyed and heated and fixed by the fixing unit 112, and a full color image is obtained on the sheet material 109.

  The photosensitive drums 101a to 101d, which have been transferred, are prepared for the next subsequent image formation after the residual toner is removed by the cleaning means 106a to 106d. Further, the color misregistration detection unit 113 detects the color misregistration amount of the toner image on the intermediate transfer belt 107, and image formation is performed at each of the image forming stations Pa to Pd so as to correct the misregistration.

  FIG. 21 to FIG. 24 are diagrams schematically illustrating a transfer image position shift state of a conventional image forming apparatus. As described above, as the type of the transfer image position shift (hereinafter referred to as image shift), as shown in FIG. 21, the position shift (top) in the scanning line writing direction (the arrow B direction in the figure) with respect to the sheet material 109. Margin), as shown in FIG. 22, misalignment (left margin) in the scanning direction (arrow A direction orthogonal to the arrow B direction in the figure), oblique misalignment as shown in FIG. As shown in FIG. 4, there is a shift in magnification error. However, in reality, the above four kinds of deviations are superimposed.

  It is considered that the main causes of such image shifts are as follows. First, in the case of the top margin of FIG. 21, the image writing timings of the image forming stations Pa to Pd having the photosensitive member as the image carrier are shifted. In the case of the left margin in FIG. 22, the image writing timing of each of the image forming stations Pa to Pd, that is, the shift of the scanning start timing in one scanning line.

  Further, the tilt deviation in the oblique direction in FIG. 23 is a deviation in the mounting angle of the scanning optical system or the angular deviation in the rotation axis of the photosensitive drums 101a to 101d. In the case of the deviation due to the magnification error in FIG. This is due to a shift in scanning line length due to an error in the optical path length from the scanning optical system of the forming stations Pa to Pd to the photosensitive drums 101a to 101d.

  Therefore, there is known a multiple image forming apparatus having correction means for eliminating these four types of image misalignment, particularly correction means for correcting image data only by electrical processing (see, for example, Patent Document 1). ). In the following, an image correction system of a multiple image forming apparatus that performs a skew correction process for electrically correcting an oblique image shift shown in FIG. 23 by data correction will be described. FIG. 25 is a block diagram showing an image correction system in a conventional multiple image forming apparatus, and FIGS. 26 to 27 are explanatory views showing an outline of skew correction processing by the multiple image forming apparatus in FIG. FIG. 10 is a diagram illustrating an example of a transfer image after skew correction processing.

  In FIG. 25, 114 is a RIP (Raster Image Processor), 115 is a video data input interface, 116 is a skew memory controller, 117 is a video data buffer memory, 118 is a registration pattern controller, and 119 is a registration pattern controller. A storage memory, 120 is a video data / output interface, and 121 is an exposure apparatus.

  Here, the RIP 114 has a function of developing image data to be printed into video data that can be formed as a print image, and the video data / input interface 115 receives the video data sent from the RIP 114. Further, the skew memory controller 116 and the video data buffer memory 117 correspond to the amount of misalignment when the image misalignment occurs as shown in FIG. 23 with respect to the video data received by the video data input interface 115. Processing for skewing the image data (shifted in the direction A in FIG. 23) is performed. In addition, the registration pattern controller 118 and the registration pattern storage memory 119 generate a registration pattern for detecting a positional deviation amount. Further, the video data / output interface 120 outputs the video data with the corrected skew amount to the exposure apparatus 121, and the exposure apparatus 121 performs an exposure process of the video data based on the video data from the video data / output interface 120. .

  Next, skew correction processing by such an image correction system will be described. In the skew correction, video data transferred from the RIP 114 is stored in the video data buffer memory 117 in units of lines to form a skew correction memory block (FIG. 26). Next, with respect to the stored video data, the line is divided and managed according to the skew amount, and skew correction is performed (FIG. 27). For example, at this time, the toner image 203 is a toner image developed by the developing unit 104 after an electrostatic latent image is formed on the photosensitive drum 101 by n-3 line data, and the toner image 202 is an n− The toner image 203 is a toner image developed by the developing unit 104 after an electrostatic latent image is formed on the photosensitive drum 101 by two line data, and the toner image 203 is electrostatically formed on the photosensitive drum 101 by n−1 line data. The toner image is developed by the developing unit 104 after the latent image is formed. Thereafter, in order to make the skew line as straight as possible, the skew is made using n-3 line data, n-2 line data, n-1 line data, as shown in the figure. A line (correction result) is created. Finally, the skew data shown in the lower part of FIG. 27 is delivered to the video data / output interface 120 while performing line shift using the skew line (correction result). As described above, a print result in which a joint after skew correction as shown in FIG. 28 is generated is obtained.

  For the top margin and the left margin, the scanning timing of each color is adjusted to correct the shift amount. Regarding the magnification error, the exposure means 103K, 103C, 103M, and 103Y in each of the image forming stations Pa to Pd are solid state elements. If so, it rarely occurs.

In the registration pattern generation process for detecting color misregistration, the detection pattern is written in a predetermined area on the registration pattern / storage memory 119. Then, the stored pattern is read by the registration pattern controller 118 and printed through the skew memory controller 116. The above configuration is extremely effective for preventing the misregistration of the four colors constituting the image forming stations Pa to Pd.
JP 2001-53962 A

  However, the conventional multiple image forming apparatus has a problem in that a step is generated at the joint of the skew-corrected data and the image quality is deteriorated. Such a problem is very serious in forming a high-quality image without color misregistration in a digital color multiple image forming apparatus.

  The present invention has been made in view of the above, and when forming an image using an optical recording element, the step of the toner image is reduced at the joint of the skew-corrected data to increase the cost. It is an object of the present invention to obtain a multiple image forming apparatus that can prevent a decrease in image quality.

  In order to solve the above-described problems, the present invention provides a plurality of photoconductors corresponding to each color, and irradiating each photoconductor with light corresponding to specific image information to form a latent image on the photoconductor. An exposure unit for forming, a developing unit for developing the latent image into a visible image, and a transfer unit for transferring the visible image to a transfer material to form a toner image, and In a multiplex image forming apparatus for forming a multicolor image by superimposing a single color image formed on a body on the transfer material, the exposure means has a predetermined number of light emitting elements arranged in a line in a predetermined direction according to a predetermined rule A light emitting element array constituted by a plurality of element groups consisting of: and a light emission control means for controlling each light emitting element to emit light in a first light emission order within each element group of the light emitting element array; And the light emission control means includes a skewer. When there is a seam in the corrected data, the first light emission order of the light emitting elements in a part of the element groups is changed to the second light emission order so that the seam is smooth. The light emission order changing function is configured.

  According to the present invention, the order of light emission can be changed with respect to a part of the element group in the light emitting element array configured in the exposure unit, and the toner image at the joint of the skew-corrected data can be changed. Since the step can be reduced, it is possible to obtain a multiple image forming apparatus capable of preventing image deterioration without increasing cost.

  In addition, since the light emitting element of the light emitting element in which element group in the element group is changed according to the amount of inclination of the image, the multiple image forming apparatus capable of preventing image deterioration more effectively. can get.

  Further, according to the present invention, it is determined which light emitting element of the light emitting element in the light emitting element is to be changed in accordance with the inclination direction of the image, so that the image deterioration can be prevented more effectively. A multi-image forming apparatus that can be obtained is obtained.

  Further, according to the present invention, skew correction is not performed by first emitting light from the light emitting element at the end in the element group and finally emitting light from the light emitting element at the center. In such a case, it is possible to form the multiple image forming apparatus which can be formed so that the pixels between the adjacent element groups are more connected, and the image quality can be improved. Furthermore, even when skew correction is performed (when there is an image tilt), as described above, a multiple image that can improve image quality by changing the order of light emission for a part of the element group. A forming device is obtained.

  Further, according to the present invention, the position of each light emitting element is shifted in the sub-scanning direction in advance in the element group in response to a temporal shift in the light emission timing of each light emitting element in the element group. Even when skew correction is not performed (when there is no inclination of the image), for example, a line image in the arrangement direction of the light emitting element array can be formed more linearly, so that a multiple image that can improve image quality A forming device is obtained. Further, even when skew correction is performed (when there is an image tilt), as described above, multiple images that can prevent image quality deterioration by changing the light emission order for a part of the element group. A forming device is obtained.

  A multiple image forming apparatus according to a first aspect of the present invention includes a plurality of photoconductors provided corresponding to each color, and each photoconductor is irradiated with light corresponding to specific image information to form a latent image on the photoconductor. Each of the photosensitive members has an exposure unit that forms a latent image, a developing unit that develops the latent image into a visible image, and a transfer unit that transfers the visible image onto a transfer material to form a toner image. In a multiplex image forming apparatus for forming a multicolor image by superimposing a formed single color image on a transfer material, an exposure unit is an element group composed of a predetermined number of light emitting elements arranged in a line in a predetermined direction according to a predetermined rule. And a light emission control means for controlling each light emitting element to emit light in the first light emission order within each element group of the light emitting element array, the light emission control means comprising: If there is a seam in the skew-corrected data And a light emission order changing function for changing the first light emission order of the light emitting elements in a part of the element groups to the second light emission order so that the joint is smooth. Therefore, the step of the toner image at the joint of the skew-corrected data can be reduced.

  In the multiple image forming apparatus according to the second aspect of the present invention, in the above invention, the light emission order changing function of the light emission control means is such that the image in the direction substantially orthogonal to the arrangement direction of the light emitting element array (hereinafter referred to as sub-scanning direction) The light emission order of the first light emitting elements in a part of the element groups is changed to the second light emission order according to the amount of inclination, and the image at the joint of the skew-corrected data is characterized. According to the inclination amount, the light emission order can be changed so as to reduce the level difference of the joint of the skew-corrected data.

  In the multiple image forming apparatus according to the third aspect of the present invention, the light emission order changing function of the light emission control means is the first of the light emitting elements in a part of the element group according to the tilt direction of the image in the sub-scanning direction. The light emission order is changed to the second light emission order, and the step of the seam of the skew-corrected data is reduced according to the inclination direction of the image at the joint of the skew-corrected data. Thus, the light emission order can be changed.

  In the multiple image forming apparatus according to the fourth invention, in the above invention, the first light emission order is an order in which the light emitting elements emit light in order from the light emitting element at the end in the element group to the light emitting element at the central part. In the element group, light is emitted in order from the outer light-emitting element toward the light-emitting element in the center, and the connection of pixels between adjacent light-emitting elements in the adjacent element group is further smoothed. It has the effect that it can be made.

  In the multiple image forming apparatus according to a fifth aspect of the present invention, in the above invention, the light emitting element array is formed by shifting the position of each light emitting element in the sub-scanning direction within the element group, and the second light emitting sequence is the light emitting element array. The light emitting elements are sequentially emitted so that the locus of the irradiation position on the photosensitive member by the light emitting elements is parallel to a straight line orthogonal to the sub-scanning direction. Corresponding to the timing shift, the position of each light emitting element is shifted in the sub-scanning direction in advance in each element group, so that the light emission sequence that can reduce the step difference of the skew-corrected data seam It has the effect | action that can be obtained.

  Embodiments of a multiple image forming apparatus according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this embodiment.

(Embodiment 1)
An object of the multiple image forming apparatus according to the present invention is to prevent a decrease in image quality without increasing the cost by reducing a step of a toner image at a seam of skew-corrected data. This is realized by changing the order of light emission with respect to a part of the element group in the light emitting element array configured in the exposure unit according to the tilt direction. In addition, even when skew correction is not performed (when there is no image tilt), light is emitted first from the light emitting element at the end in the element group, and finally at the center part so that the image quality can be further improved. The light emitting elements are controlled to emit light, and the positions of the respective light emitting elements are previously shifted in the sub scanning direction in the element group in response to the temporal shift of the light emission timing of each light emitting element in the element group. It will be realized.

  FIG. 1 is a diagram illustrating a configuration example of a multiple image forming apparatus according to Embodiment 1 of the present invention. In FIG. 1, 1a to 1d are photosensitive drums, 2a to 2d are charging means, 3K, 3C, 3M and 3Y are exposure means, 4a to 4d are developing means, 5a to 5d are transfer means, and 6a to 6d are cleaning means. , 7 is an intermediate transfer belt, 8 is a sheet feeding roller, 9 is a sheet material, 10 is a sheet feeding table, 11 is a sheet material transfer roller, 12 is a fixing unit, 13 is a color misregistration detecting unit, and Pa is a first image. A forming station, Pb is a second image forming station, Pc is a third image forming station, and Pd is a fourth image forming station.

  In the multiple image forming apparatus, four image forming stations Pa, Pb, Pc, and Pd are arranged. Each image forming station Pa, Pb, Pc, and Pd has photosensitive drums 1a, 1b, 1c, and 1d as photosensitive members. Have each. Further, around each photosensitive drum 1a, 1b, 1c, 1d, dedicated charging means 2a, 2b, 2c, 2d and light corresponding to the image information are applied to each photosensitive drum 1a, 1b, 1c, 1d. Exposure means 3K, 3C, 3M and 3Y for irradiation, developing means 4a, 4b, 4c and 4d, transfer means 5a, 5b, 5c and 5d, and cleaning means 6a, 6b, 6c and 6d are arranged, respectively. Here, the image forming stations Pa, Pb, Pc, and Pd form a black image (K), a cyan image (C), a magenta image (M), and a yellow image (Y), respectively.

  On the other hand, an endless belt-like intermediate transfer belt 7 is disposed below the photosensitive drums 1a, 1b, 1c, and 1d so as to pass through the image forming stations Pa, Pb, Pc, and Pd, and moves in the direction of arrow A. .

  In this configuration, first, a yellow component color latent image of the image information is formed on the photosensitive drum 1d by the known electrophotographic process means of the charging means 2d of the fourth image forming station Pd and the exposure means 3Y. The latent image is visualized as a yellow toner image by a developer having yellow toner by the developing unit 4d, and the yellow toner image is transferred to the intermediate transfer belt 7 by the transfer unit 5d.

  On the other hand, while the yellow toner image is being transferred to the intermediate transfer belt 7, a latent image having a magenta component color is formed at the third image forming station Pc as in the case of the fourth image forming station Pd. Subsequently, a magenta toner image using magenta toner is obtained by the developing unit 4c, and the magenta toner image is transferred to the intermediate transfer belt 7 which has been transferred at the previous fourth image forming station Pd. And is superimposed on the yellow toner image.

  Thereafter, the cyan toner image and the black toner image are formed in the same manner at the second and first image forming stations Pb and Pa, and the superposition of the four color toner images on the intermediate transfer belt 7 is completed. Then, after the four color toner images formed on the intermediate transfer belt 7 by the sheet material transfer roller 11 are collectively transferred onto the sheet material 9 such as paper fed from the paper feed table 10 by the paper feed roller 8. The sheet is conveyed and heated and fixed by the fixing unit 12, and a full-color image is obtained on the sheet material 9.

  The photosensitive drums 1a, 1b, 1c, and 1d that have been transferred are prepared for the next subsequent image formation after the residual toner is removed by the cleaning means 6a, 6b, 6c, and 6d.

  As described above, the color misregistration for detecting the color misregistration of the image (toner image) formed by the fourth to first image forming stations Pd to Pa and superposed on the intermediate transfer belt 7 and transferred. The detecting means 13 is provided on the side of the intermediate transfer belt 7 coming out from the first image forming station Pa. The color misregistration detection unit 13 detects the position of the color misregistration detection pattern toner image formed on the intermediate transfer belt 7.

  FIG. 2 is a block diagram showing in detail the configuration of the color misregistration detection means in the first embodiment of the present invention. In FIG. 2, 13a is an LED, 13b is an LED lens, 13c is a photodiode lens, and 13d is a photodiode. In addition, the sensor units having such a configuration are installed at two locations near the scanning start position and near the scanning end position of the exposure units 3K, 3C, 3M, and 3Y.

  In the color misregistration detection means 13, the light emitted from the LED 13a is irradiated onto a color misregistration detection pattern toner image (not shown) formed on the intermediate transfer belt 7 via the LED lens 13b. In a region where there is no color misregistration detection pattern toner image, the light from the LED 13a is reflected by the surface of the intermediate transfer belt 7 and then enters the photodiode 13d via the photodiode lens 13c. In the (region where the toner image is attached), color misregistration is detected by utilizing the fact that the light of the LED 13a is irregularly reflected by the toner image and does not enter the photodiode 13d.

  The color misregistration detection operation will be described in more detail. FIG. 3 is a diagram for explaining the details of the color misregistration detection means in the first embodiment of the present invention. Similar to the printing operation described above, a registration pattern such as a predetermined C-shape is transferred as a toner image for each color at a predetermined interval, and the position shift (color) of each color is performed by the sensor unit described above. Measure the deviation. In the case of a C-shaped registration pattern, a shift in the position of the intermediate point of the registration pattern in the vicinity of both ends of the sensor unit is detected, and for example, the time difference is obtained using the rotational speed of the intermediate transfer belt 7. it can. Then, the positional deviation of the color misregistration pattern toner image is detected and fed back to the color misregistration correction means to adjust the light emission timing of each color exposure means 3K, 3C, 3M, 3Y.

  The first embodiment is different from the conventional image forming apparatus in the configuration of exposure means 3K, 3C, 3M, 3Y. That is, an element group in a light emitting element array of organic EL (ElectroLuminescence) light emitting elements is arranged in a curved shape in the main scanning direction of the photosensitive drums 1a, 1b, 1c, and 1d, and an element group in a joint step portion by color misalignment skew correction. The organic EL array exposure head is adapted to change the light emission order of the light emitting elements. The organic EL array exposure head has an optical path length shorter than that of the laser scanning optical system, is compact, can be disposed close to the photosensitive drums 1a, 1b, 1c, and 1d, and can be downsized as a whole. Have

  FIG. 4 is a perspective view schematically showing an enlarged part of the exposure means 3Y used in the multiple image forming apparatus according to the first embodiment of the present invention. FIG. 5 is a perspective view according to the first embodiment of the present invention. FIG. 6 is a cross-sectional view of the exposure means 3Y in the sub-scanning direction, and FIG. 6 is a cross-sectional view showing the configuration in the vicinity of the light emitting portion of the organic EL light emitting element array according to Embodiment 1 of the present invention shown in FIG. Here, since the exposure means 3K, 3C, 3M have the same form as the exposure means 3Y, description thereof is omitted.

  In FIG. 4, 40 is an organic EL light emitting element array, 41 is a housing, 42 is a positioning pin, 43 is a screw insertion hole, 44 is a glass substrate, 45 is a light emitting portion, 46 is a gradient index rod lens array, 47 is This is a gradient index rod lens. In FIG. 5, 48 is a cover, 49 is a fixed leaf spring, and 50 is a light emitting portion. Further, in FIG. 6, 51 is a thin film transistor (hereinafter referred to as TFT (Thin Film Transistor)), 52 is a first insulating film, 53 is an anode, 54 is a second insulating film, 55 is a hole, 56 is a bank, 57 Is a hole injection layer, 58 is a light emitting layer, 59a is a cathode first layer, 59b is a cathode second layer, 60 is an inert gas, and 61 is a cover glass.

  As shown in FIG. 4, the organic EL light emitting element array 40 is held in a long housing 41. Each of the positioning pins 42 provided at both ends of the long housing 41 is inserted into positioning holes (not shown) facing the housing 41 and fixed through the screw insertion holes 43 provided at both ends of the long housing 41. The exposure means 3K, 3C, 3M, 3Y are fixed at predetermined positions.

  The exposure unit 3 </ b> Y places the light emitting unit 45 of the organic EL light emitting element array 40 on the glass substrate 44 and is driven by the TFT 51 formed on the same glass substrate 44. The gradient index rod lens array 46 constitutes an imaging optical system, and a gradient index rod lens 47 is stacked on the front surface of the light emitting unit 45.

  4 and 5, the housing 41 is formed of an opaque member, covers the periphery of the glass substrate 44, and faces the photosensitive drums 1a, 1b, 1c, 1d (lower side in FIG. 5). Open. In this way, light is emitted from the gradient index rod lens 47 to the photosensitive drums 1a, 1b, 1c, and 1d. A light-absorbing member (paint) is provided on the surface of the housing 41 that faces the end surface of the glass substrate 44.

  As shown in FIG. 5, the exposure means 3 </ b> Y includes an organic EL light-emitting element array 40 attached to the rear surface of the gradient index rod lens array 46 in the housing 41, and a rear surface of the housing 41. An opaque cover 48 that shields the organic EL light emitting element array 40 is provided.

  Further, the cover 48 is pressed against the back surface of the housing 41 by the fixed plate spring 49 to seal the inside of the housing 41 in a light-tight manner. That is, the glass substrate 44 is optically sealed with the housing 41 by the fixed plate spring 49. A plurality of fixed leaf springs 49 are provided in the longitudinal direction of the housing 41.

  The housing 41 of the exposure means 3Y is formed of an opaque member, and the back surface thereof is covered with an opaque cover 48, so that fluorescent light incident on the back surface of the organic EL light emitting element array 40 and ultraviolet rays from the sun are organically emitted. Reaching the light emitting part 50 of the EL light emitting element array 40 is prevented.

  As shown in FIG. 6, the organic EL light emitting element array 40 includes, for example, a TFT 51 made of polysilicon having a thickness of 50 nm for controlling light emission of the light emitting unit 50 on a glass substrate 44 having a thickness of 0.5 mm. Corresponding to each of the light emitting units 50 arranged in a row in a direction perpendicular to the paper surface of FIG.

Further, a first insulating film 52 made of SiO ₂ having a thickness of about 100 nm is formed on the glass substrate 44 excluding the contact hole on the TFT 51, and light emission is performed so as to be connected to the TFT 51 through the contact hole. An anode 53 made of ITO (Indium Tin Oxide) having a thickness of 150 nm, for example, is formed at the position where the portion 50 is formed.

A second insulating film 54 made of SiO _{2 having a} thickness of, for example, about 120 nm is formed on a portion of the first insulating film 52 and the anode 53 corresponding to positions other than the position where the light emitting unit 50 is formed. On the other hand, on the anode 53 not covered with the second insulating film 54, for example, a hole injection layer 57 having a thickness of 50 nm and a light emitting layer 58 having a thickness of 50 nm are sequentially stacked.

  A bank 56 made of polyimide having a thickness of 2 μm, for example, surrounds a region corresponding to the light emitting unit 50 including the hole injection layer 57 and the light emitting layer 58, that is, the region corresponding to the light emitting unit 50 is a hole 55. Is provided. For example, a cathode first layer 59a made of Ca having a thickness of 100 nm and a cathode made of Al having a thickness of 200 nm so as to cover the upper surface of the light emitting layer 58 in the hole 55 of the bank 56 and the inner and outer surfaces of the hole 55 of the bank 56. The second layer 59b is sequentially formed. Then, by covering the upper surface with a cover glass 61 having a thickness of, for example, about 1 mm through an inert gas 60 such as nitrogen gas, the light emitting unit 50 of the organic EL light emitting element array 40 is configured.

  Light emission from the light emitting unit 50 having such a configuration is performed on the glass substrate 44 side. Moreover, since such an organic EL light-emitting element can be easily manufactured on the glass substrate 44, the manufacturing cost can be reduced. The material used for the hole injection layer 57 and the material used for the light emitting layer 58 are known various types as disclosed in, for example, JP-A-10-12377 and JP-A-2000-323276. Since a thing can be utilized, the detailed description is abbreviate | omitted.

  FIG. 7 is a block diagram showing a schematic configuration of the control unit of the optical head constituting the exposure apparatus according to Embodiment 1 of the present invention. In FIG. 7, 62 is a light emitting element (yellow) line head, 63 is a host computer, 64 is a control unit, 65 is data processing means, 66 to 69 are storage means, 70 is light emission control means, and 71 is a light emitting element ( A magenta line head, 72 is a light emitting element (cyan) line head, and 73 is a light emitting element (black) line head.

  In FIG. 7, the host computer 63 forms print data and transmits it to the control unit 64 of the multiple image forming apparatus. The control unit 64 of the multiple image forming apparatus includes data processing means 65, storage means 66 to 69, and light emission control means 70. The light emitting element line heads 62, 71, 72, and 73 are light emitting element arrays of respective colors, and correspond to yellow, magenta, cyan, and black, respectively.

  Based on the print data transmitted from the host computer 63, the data processing means 65 performs processing such as color separation, gradation processing, development of image data into a bitmap, and color misregistration adjustment. Then, the data processing unit 65 outputs the image data to each storage unit 66 to 69 for each color component by line.

  Storage means 66-69 store image data for controlling light emission of the light emitting element line heads 62, 71, 72, 73 of yellow, magenta, cyan, and black constituting the image forming stations Pd, Pc, Pb, Pa. This is stored in memory such as SRAM (Static Random Access Memory).

  The light emission control means 70 reads image data from the storage means 66 to 69 according to a predetermined light emission rule in order to control light emission of the light emitting element line heads 62, 71, 72, 73 of each color, and based on the read image data. The light emitting element line heads 62, 71, 72, 73 corresponding to the light emitting elements control light emission. Here, the predetermined light emission rule means that the light emission state of each light emitting element is controlled based on the configuration shown in FIGS. 8 and 9 to be described later, for example.

  FIG. 8 is a diagram showing an example of the configuration of the light-emitting element line head according to the first embodiment of the present invention, and FIG. 9 shows the light-emitting element line head according to the first embodiment of the present invention configured as shown in FIG. It is a block diagram which shows an example of the circuit structure which drives. 8, 62a to 62n are element groups, 62ai to 62ni (i = 1 to 8) are light emitting elements, and in FIG. 9, 160 is a row selection terminal, and 161 is a column selection terminal. 8 and 9, the light emitting element (yellow) line head 62 will be described as an example. However, the light emitting element (magenta) line head 71, the light emitting element (cyan) line head 72, and the light emitting element (black) are described. Since the line head 73 is the same, the description thereof is omitted.

  In FIG. 8, the light emitting element (yellow) line head 62 has a plurality of light emitting elements 62ai to 62ni (i = 1 to 8) in the main scanning direction Y of the photosensitive drum 1d (the axial direction of the photosensitive drum 1d). Is provided. The plurality of light emitting elements 62ai to 62ni are grouped into eight light emitting elements 62ai to 62ni to form a plurality of element groups 62a to 62n. Here, eight light emitting elements 62a1 to 62a8 arranged adjacent to each other constitute an element group 62a,..., Eight light emitting elements 62n1 to 62n8 arranged adjacent to each other constitute an element group 62n. ing. In one element group 62a to 62n of the photosensitive drum 1d, the light emitting elements 62ai to 62ni are arranged in the main scanning direction Y at a pitch p between the light emitting elements. The distance between the light emitting elements arranged in the sub-scanning direction X (the direction orthogonal to the axial direction of the photosensitive drum 1d) is the element pitch 62 in the main scanning direction Y of the photosensitive drum 1d. (a to n) are arranged at a pitch of a distance q (= p / 8) divided by the number of light emitting elements i (here, i = 8). At this time, the light emitting elements 62j1 to 62j8 arranged at the same position in the sub-scanning direction X are not arranged in one element group 62j. In the example of FIGS. 8 and 9, the light emitting element 62j1 is used as a reference, and 62j2 to 62j8 are sequentially shifted in the sub-scanning direction X (the lower direction in the figure) by pitch q.

  FIG. 9 shows a configuration in which the light-emitting elements 62ai to 62ni are divided and driven by a so-called passive matrix method. The row selection terminal 160 includes terminals y1 to y8 connected to the light emitting elements 62j1 to 62j8 (j = a to n) of the element groups 62a to 62n, respectively. The row selection terminal 160 is a terminal that controls all the light emitting elements 62a1 to 62n8 within one line time while sequentially switching the selection of the terminals y1 to y8 within one line time in the printing operation.

  The column selection terminal 161 has terminals xa to xn connected to the respective element groups 62a to 62n (all of the light emitting elements 62j1 to 62j8 (j = a to n)). The column selection terminal 161 is the other terminal for selecting a light emitting element connected to the row terminal when a specific row terminal is selected. Each column selection terminal 161 is based on the image data of the selected light emitting element. A terminal for applying a voltage or current for controlling ON / OFF (lighting / non-lighting) of the light emitting element to the terminals xa to xn.

  The operation will be described with a specific example. When the row control terminal y1 in the row selection terminal 160 is selected by the light emission control unit 70, the light emission control unit 70 selects the light emitting elements 62a1, 62b1,. Are read from the storage means 66, and the light emission control means 70 controls the column terminals xa to xn based on the image data of the light emitting elements 62a1, 62b1,..., 62n1, and the light emitting elements 62a1, 62b1,. , 62n1 ON / OFF (lighting / non-lighting) is controlled. Subsequently, when the y2 row terminal of the row selection terminal 160 is selected by the light emission control means 70, the column is similarly based on the image data of the light emitting elements 62a2, 62b2,..., 62n2 read from the storage means 66. The terminals xa to xn are controlled to control ON / OFF (lighting / non-lighting) of the light emitting elements 62a2, 62b2,. Similarly, the same processing is repeated for the row terminals y3 to y8 of the row selection terminal 160 to control ON / OFF (lighting / non-lighting) of all the light emitting elements within the time of one line. Further, the same operation is performed after the next line, and light emission control of the light emitting element is performed to form an image.

  As described above, in FIG. 9, any one of the eight row terminals y1 to y8 in the row selection terminal 160 is selected, and only the light emitting elements 62a1 to 62n8 connected to the selected row terminal are turned ON / OFF ( The time-division driving is performed within the time of one line so that the lighting / non-lighting is controlled. Here, by applying voltage or current between the row terminal and the column terminal connected to the light emitting elements 62a1 to 62n8, the light emitting elements 62a1 to 62n8 connected to the terminals emit light.

  As described above, the light-emitting element array configured as shown in FIGS. 8 and 9 is divided into eight parts in which the light-emitting elements that are sequentially selected at the row terminal are controlled to emit light every time the time of one line is divided into eight. Passive matrix drive. In light emission timing, the light emitting elements 62a1, 62b1,..., 62n1 are the same timing group, and similarly, the light emitting elements 62a2, 62b2,..., 62n2 are the same timing group, and the light emitting elements 62a8, 62b8,. .., 62n8 are the same timing group.

  10 to 12 are diagrams schematically showing toner image formation on the photosensitive drum by the light emitting element line head according to the first embodiment of the present invention having the configuration shown in FIGS. 8 and 9. FIG. 10 is a diagram schematically illustrating a first dot toner image formation state according to the first embodiment of the present invention, and FIG. 11 is a schematic view illustrating a third dot toner image formation state according to the first embodiment of the present invention. FIG. 12 is a diagram schematically showing a state of forming an 8-dot toner image in Embodiment 1 of the present invention. 10 to 12, 74a1 to 74n8 are toner images on the photosensitive drum 1d formed by the light emitting elements 62a1 to 62n8. Here, in order to make the explanation easy to understand, a case where all the light emitting elements 62a1 to 62n8 emit light will be described as an example.

  As shown in FIG. 10, the first dot is the toner image 74j1 (on the photosensitive drum 1d formed by the light emitting element 62j1 (j = a to n) emitted at the first timing of the element groups 62a to 62n. j = a to n). Next, although not shown, the second dot is a toner image 74j2 (j on the photosensitive drum 1d formed by the light emitting element 62j2 (j = a to n) emitted at the second timing of the element groups 62a to 62n. = A to n). Similarly, as shown in FIG. 11, the third dot shows a toner image on the photosensitive drum 1d by the element 62j3 (j = a to n) emitted up to the third of the light emitting element groups 62a to 62n. ing. The above processing is repeated until the 8th dot. As shown in FIG. 12, in the same manner as described above, the eighth dot is a toner image on the photosensitive drum 1d by the light emitting elements 62j8 (j = a to n) emitted up to the eighth element group 62a to 62n. 74j8 (j = a to n) are formed.

  Here, the photosensitive drum 1d rotates in the X direction, which is the sub-scanning direction in FIG. 8, and the light emitting elements 62j1 to 62j8 (j = a to n) in the element groups 62a to 62n are pitched in the X direction. Since the distance q is shifted, each light emitting element 62j1 is arranged such that the distance q the photosensitive drum 1d moves in the X direction and the pitch q at the time of each light emission timing in the eight-part passive matrix drive. By controlling the light emission order and timing of .about.62j8 (j = a to n), the toner images 74a1 to 74n8 formed on the photosensitive drum 1d can be formed on a substantially straight line as shown in FIG. . Further, for example, a toner image having no step in the X direction is also formed between the toner image 74a2 and the toner image 74b1 formed by the element 62a2 and the light emitting element 62b1 adjacent to each other between the element groups.

  As described above, in the multiple image forming apparatus having a plurality of image forming stations Pa, Pb, Pc, and Pd, the scanning lines irradiated by the exposure units 3K, 3C, 3M, and 3Y rotate in the direction of arrow C in FIG. The image information is exposed on the photosensitive drums 1a, 1b, 1c, and 1d, and different colors are sequentially applied to the same surface of the same intermediate transfer belt 7 conveyed in the direction of arrow A in FIG. 1 through a known image forming process. The toner images are transferred and superimposed. At this time, if the transfer image position at each of the image forming stations Pa, Pd, Pc, and Pd deviates from the ideal position, for example, in the case of a multicolor image, the image intervals of different colors are shifted or overlapped. Further, in the case of a color image, a difference in color, and if the degree becomes more severe, a color shift appears and the quality of the image is significantly deteriorated.

  Therefore, in the first embodiment, in order to eliminate the three types of misregistration that cause the color misregistration described in the background art, first, as for the top margin and the left margin, the scanning lines 3K, 3C, 3M are the same as in the prior art. , 3Y scanning timing is electrically adjusted to correct the shift amount. As for the skew correction, the same correction as the conventional technique is performed until the line shift stage. Thereafter, processing (smoothing processing) is performed to reduce the influence of the joint after skew correction according to the present invention in the formed image. Hereinafter, the smoothing process will be described.

  13 to 15 are diagrams illustrating an example for explaining the smoothing process according to the first embodiment of the present invention, and FIG. 13 illustrates the arrangement of the light emitting elements of the light emitting element line head according to the first embodiment of the present invention. FIG. 14 is a diagram showing a part of the state, and FIG. 14 is a diagram showing a part of the toner image before the smoothing process on the photosensitive drum exposed by the element arrangement of the light emitting element line head according to the first embodiment of the present invention. FIG. 15 is a view showing a part of the toner image after the smoothing process on the photosensitive drum exposed by the element arrangement of the light emitting element line head according to the first embodiment of the present invention. FIGS. 16 to 18 are diagrams showing another example for explaining the smoothing process according to the first embodiment of the present invention. FIG. 16 shows the light emitting element line head according to the first embodiment of the present invention. FIG. 17 is a diagram illustrating a part of the arrangement state of the light emitting elements, and FIG. 17 is a diagram illustrating a toner image before the smoothing process on the photosensitive drum exposed by the element arrangement of the light emitting element line head according to the first embodiment of the present invention. FIG. 18 is a diagram illustrating a part of the toner image after the smoothing process on the photosensitive drum exposed by the element arrangement of the light emitting element line head according to the first embodiment of the present invention.

  A pixel position (skew point) for performing skew correction is determined in advance according to the skew amount. Since the number of skew points and the memory capacity necessary for performing line shift scanning of image data are proportional, it is desirable to reduce the number of skew points as much as possible. In addition, there is no particular problem in fixing the skew point of the image data at a specific pixel position. In FIG. 13 to FIG. 18, light emitting element groups serving as skew points are shown as 74 f and 74 g. Note that the numbers (1 to 8) described on the element group toner images 74f and 74g in FIGS. 14, 15, 17, and 18 represent the element emission timing order.

  In the state of the element arrangement of FIG. 13, when the element emission timing is emitted in the order of numbers 1 to 8, it is affected by the fact that the image data is shifted by one line between the element group 74f and the element group 74g by skew correction. Thus, a toner image as shown in FIG. 14 is formed. That is, a step is generated between toner images 74f2 and 74g1 between the element groups 74f and 74g (hereinafter referred to as adjacent element toner images). The effect of the step appears in the output image as a line image break or color unevenness.

  Therefore, in order to reduce the occurrence of this step, the light emission timing of the element group 62f is changed. That is, the light emission order of the light emitting elements of the element group 62f is changed to the order shown in FIG. 15 such that the first is changed to 62f1, the second is changed to 62f2, and the third is changed to 62f3. A toner image as shown in FIG. Therefore, the level difference between the adjacent toner images 74f2 and 74g1 between the element groups 74f and 74g is reduced, so that it is possible to suppress the occurrence of line image breaks and color unevenness in the output image.

  A smoothing process in the case where a joint step after skew correction occurs in the opposite direction to the case of FIGS. 13 to 15 will be described with reference to FIGS. As in the case of FIG. 13, when the light emission timings of the elements are emitted in the order of numbers 1 to 8 in the state of the light emitting element array of FIG. 16, a toner image as shown in FIG. 17 is formed before the smoothing process. That is, a step is generated between adjacent element toner images 74f2 and 74g1 between the element groups 74f and 74g.

  Therefore, in order to reduce the occurrence of this step, the light emission timing of the element group 62g is changed. That is, the light emission order of the light emitting elements of the element group 62g is changed to the order shown in FIG. 18 so that the first is changed to 62g5, the second is changed to 62g4, the third is changed to 62g3, and so on. A toner image as shown in FIG. 18 is formed. Therefore, the level difference between the adjacent toner images 74f2 and 74g1 between the element groups 74f and 74g is reduced, so that it is possible to suppress the occurrence of line image breaks and color unevenness in the output image.

  In addition, as a structure which changes the light emission order of the light emitting element in a specific element group by a smoothing process, the structure as shown, for example in FIG. 19 can be considered. In FIG. 19, reference numeral 162 denotes a switch means that controls connection of the terminals y1 to y8 of the row selection terminal 160 and the light emitting elements of the element groups 62f and 62g to be subjected to the smoothing process. In accordance with the light emission order in the element group as shown in FIG. 11 or FIG. 12, which row terminal is connected to which light emitting element is connected. In the control of the column selection terminal 161, the light emission order of the light emitting elements as shown in FIGS. 11 and 12 can be changed by changing the image data read from the storage means 66 by the light emission control means 70 according to the light emission order. it can.

  In addition, the smoothing process is performed by changing the light emission order of the light emitting elements at the skew points according to the inclination amount and the inclination direction of the skew processed image. For example, a plurality of samples having different image tilt amounts and tilt directions are prepared in advance, and in each case, the light emission order of the light emitting elements at the skew points when performing the smoothing process is obtained as the light emission order information. At the time of the smoothing process, the light emission control unit 70 changes the light emission order at the skew points based on the light emission order information corresponding to the detected amount and inclination direction of the image.

  In the above description, an example of a yellow image has been described. However, as shown in FIG. 1, for the magenta image, cyan image, and black image, the light emission timing is changed in the same manner, and adjacent toner by line shift is used. By performing the smoothing process so as to reduce the level difference between the images, the superposition of the four color toner images on the intermediate transfer belt 7 with no color misregistration and reduced image deterioration due to the level difference is completed.

  As described above, in the first embodiment, the skew is provided by providing the light emission control means 70 that can change the order of light emission for a part of the element group in the light emitting element array configured as the exposure means. Since the difference in level of the toner image at the seam of the corrected data can be reduced, image deterioration can be prevented without increasing the cost.

  Further, by providing the light emission control means 70 that determines which light emitting element of the element group in the element group is to be changed according to the inclination amount or the inclination direction of the image, the image deterioration can be more effectively performed. Can be prevented.

  Further, by providing light emission control means 70 that first emits light from the light emitting elements at the end in the element group and finally emits light from the central light emitting element, skew correction is performed (the inclination of the image is reduced). Not only in the case of a certain state) but also in the case where no skew correction is performed (the state where there is no inclination of the image), the pixels between adjacent element groups can be formed so as to be more connected, thereby improving the image quality. be able to.

  The light emitting element line heads 62, 71, 71 formed in advance in the element group by shifting the position of each light emitting element in the sub-scanning direction in response to a temporal shift in the light emission timing of each light emitting element in the element group. By providing 72 and 73, even when skew correction is not performed (when there is no inclination of the image), for example, a line image in the arrangement direction of the light emitting element array can be formed more linearly. Can be improved. Furthermore, even when skew correction is performed (when there is an image tilt), it is possible to prevent image quality deterioration by changing the light emission order for a part of the element group as described above.

  As described above, the multiple image forming apparatus according to the present invention uses the order of the light emission timing of the toner image at the data seam that occurs when the image data is corrected only by electrical processing as the color misregistration skew correction means. Since it can be smoothed only by replacement, it can be used for, for example, a printer for the business or SOHO market, a copying machine, a facsimile machine, and a small on-demand printing machine for the small lot printing market.

1 is a schematic configuration diagram of a multiple image forming apparatus according to Embodiment 1 of the present invention. Detailed view of color misregistration detection means in Embodiment 1 of the present invention The figure for demonstrating the detail of the color shift detection means in Embodiment 1 of this invention. Exposure apparatus perspective view according to Embodiment 1 of the present invention Sectional view in the sub-scanning direction of the exposure apparatus in Embodiment 1 of the present invention Sectional drawing which shows the structure of the light emission part vicinity of the organic electroluminescent light emitting element array in Embodiment 1 of this invention. 1 is a block diagram showing a schematic configuration of a control unit of an optical head in Embodiment 1 of the present invention. Explanatory drawing which shows the yellow line head in Embodiment 1 of this invention. 1 is a block diagram illustrating a method for driving a light-emitting element in Embodiment 1 of the present invention. Explanatory drawing of toner image formation on a photoreceptor in Embodiment 1 of the present invention Explanatory drawing of toner image formation on a photoreceptor in Embodiment 1 of the present invention Explanatory drawing of toner image formation on a photoreceptor in Embodiment 1 of the present invention Explanatory drawing of smoothing processing of the joint after skew correction in Embodiment 1 of the present invention Explanatory drawing of smoothing processing of the joint after skew correction in Embodiment 1 of the present invention Explanatory drawing of smoothing processing of the joint after skew correction in Embodiment 1 of the present invention Another explanatory diagram of the smoothing process of the joint after skew correction in the first embodiment of the present invention Another explanatory diagram of the smoothing process of the joint after skew correction in the first embodiment of the present invention Another explanatory diagram of the smoothing process of the joint after skew correction in the first embodiment of the present invention 1 is a block diagram illustrating a method for driving a light-emitting element in Embodiment 1 of the present invention. Schematic configuration diagram of a conventional multiple image forming apparatus The figure which shows the error in the scanning line of the conventional multiple formation apparatus The figure which shows the error in the scanning line of the conventional multiple formation apparatus The figure which shows the error in the scanning line of the conventional multiple formation apparatus The figure which shows the error in the scanning line of the conventional multiple formation apparatus Block diagram showing an image correction system in a conventional multiple image forming apparatus Explanatory drawing which shows the skew correction process by the image correction system of FIG. Explanatory drawing which shows the skew correction process by the image correction system of FIG. Print result after skew correction

Explanation of symbols

1a to 1d Photosensitive drums 2a to 2d Charging means 3K, 3C, 3M, 3Y Exposure means 4a to 4d Developing means 5a to 5d Transfer means 6a to 6d Cleaning means 7 Intermediate transfer belt 8 Feed roller 9 Sheet material 10 Feed stand 11 Sheet material transfer roller 12 Fixing means 13 Color misregistration detecting means 13a LED
13b LED lens 13c Photodiode lens 13d Photodiode 40 Organic EL light emitting element array 41 Housing 42 Positioning pin 43 Screw insertion hole 44 Glass substrate 45 Light emitting part 46 Refractive index distribution type rod lens array 47 Refractive index distribution type rod lens 48 Cover 49 Fixed Leaf spring 50 Light emitting portion 51 Thin film transistor 52 First insulating film 53 Anode 54 Second insulating film 55 Hole 56 Bank 57 Hole injection layer 58 Light emitting layer 59a Cathode first layer 59b Cathode second layer 60 Inert gas 61 Cover glass 62 light emitting element (yellow) line head 63 host computer 64 control unit 65 data processing means 66 to 69 storage means 70 light emission control means 71 light emitting element (magenta) line head,
72 Light Emitting Element (Cyan) Line Head 73 Light Emitting Element (Black) Line Head Pa to Pd Image Forming Station

Claims (5)

A plurality of photoconductors provided corresponding to the respective colors, exposure means for irradiating each photoconductor with light corresponding to specific image information to form a latent image on the photoconductor, and developing the latent image Development means for converting the visible image onto a transfer material, and transfer means for forming a toner image by transferring the visible image to a transfer material, and transferring the monochrome image formed on each of the photoconductors to the transfer material. In a multiple image forming apparatus that forms a multicolor image by superimposing on
The exposure means includes
A light emitting element array configured by a plurality of element groups each including a predetermined number of light emitting elements arranged in a line in a predetermined direction according to a predetermined rule;
Light emission control means for controlling each light emitting element to emit light in a first light emission order within each of the element groups of the light emitting element array;
With
The light emission control means is configured so that when the skew-corrected data has a seam, the first light emission order of the light emitting elements in a part of the element groups is made smooth. A multiple image forming apparatus having a light emission order changing function for changing to a second light emission order. The light emission order changing function of the light emission control means is based on the amount of inclination of the image in the direction substantially orthogonal to the arrangement direction of the light emitting element array (hereinafter referred to as sub-scanning direction). The multiple image forming apparatus according to claim 1, wherein the light emission order of the first light emitting elements is changed to a second light emission order. The light emission order changing function of the light emission control means changes the first light emission order of the light emitting elements in the partial element group to the second light emission order in accordance with the inclination direction of the image in the sub-scanning direction. The multiple image forming apparatus according to claim 1, wherein: 4. The light emitting device according to claim 1, wherein the first light emitting sequence is a sequence in which the light emitting devices emit light in order from the light emitting device at the end in the device group to the light emitting device at the center. The multiple image forming apparatus described in 1. The light emitting element array is formed by shifting the position of each light emitting element in the sub scanning direction within the element group,
The second light emission sequence is a sequence in which the light emitting elements sequentially emit light so that the locus of the irradiation position of the light emitting elements on the photoconductor in the light emitting element array is parallel to a straight line orthogonal to the sub-scanning direction. 5. The multiple image forming apparatus according to claim 1, wherein

Images