JP2009143220A - Exposure head and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique whereby a latent image can be formed by a sufficient amount of light. <P>SOLUTION: The exposure head includes an imaging optical system arranged in a first direction, first light emitting elements and second light emitting elements which form light-collected parts adjacent to each other in the first direction by emitting the light imaged by the imaging optical system and are disposed at different positions in a second direction orthogonal or nearly orthogonal to the first direction, and wiring cables which are electrically connected with the light emitting elements and drawn out of the light emitting elements to one side of the second direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an exposure head that forms an image of a light beam emitted from a light emitting element with a lens, and an image forming apparatus using the exposure head.

  As such an exposure head, a line head using a light-emitting element array configured by arranging a plurality of light-emitting elements in a straight line has been proposed, for example, as described in Patent Document 1. In such a line head, a light beam emitted from each of a plurality of light emitting elements included in the light emitting element array is imaged as a spot by a lens, and a spot latent image is formed on the image plane. Thus, the line head described in Patent Document 1 forms a plurality of spot latent images side by side in the main scanning direction.

JP 2000-158705 A

  By the way, in order to form a better spot latent image, it is desired to increase the size of each light emitting element and form a spot latent image with a sufficient amount of light. However, it is not easy to increase the size of the light emitting element in the above configuration in which a plurality of light emitting elements are arranged in a straight line. This is because when the light emitting element is enlarged, interference may occur between adjacent light emitting elements. In addition, when the pitch between the light emitting elements is reduced to increase the resolution, it is even more difficult to increase the size of the light emitting elements.

  The present invention has been made in view of the above problems, and an object thereof is to provide a technique capable of forming a latent image with a sufficient amount of light.

  In order to achieve the above object, an exposure head according to the present invention emits light that is imaged by an imaging optical system arranged in a first direction and is imaged by the imaging optical system and is adjacent to the first direction. A first light-emitting element and a second light-emitting element that form an optical portion and are arranged in a second direction orthogonal or substantially orthogonal to the first direction, and are electrically connected to the first light-emitting element and in the second direction And a second wiring led out from the light emitting element on one side in the second direction and electrically connected to the second light emitting element. It is said.

  In order to achieve the above object, an image forming apparatus according to the present invention forms an image on a latent image carrier by a latent image carrier, an imaging optical system arranged in the first direction, and an imaging optical system. A first light emitting element and a second light emitting element arranged at different positions in a second direction orthogonal to or substantially orthogonal to the first direction while forming a latent image adjacent to the first direction on the latent image carrier. The element, the first wiring that is electrically connected to the first light emitting element and drawn from the light emitting element to one side in the second direction, and the one side in the second direction that is electrically connected to the second light emitting element And an exposure head having a second wiring led out from the light emitting element, and a developing unit for developing the light condensing part formed on the latent image carrier by the exposure head.

  In the invention configured as described above, the first light emitting element and the second light emitting element forming the condensing portion adjacent to each other in the first direction are arranged at different positions in the second direction. Therefore, it is possible to enlarge the first light emitting element and the second light emitting element, and it is possible to satisfactorily form a latent image by forming a condensing portion with a sufficient amount of light.

  Moreover, in this invention, each wiring connected to these light emitting elements is pulled out to the one side of a 2nd direction. Therefore, each wiring can be routed together. The present invention is also preferable in that the wiring can be easily routed.

  Further, in the present invention in which each wiring is drawn out to one side in the second direction as described above, a circuit electrically connected to the first wiring and the second wiring may be arranged on one side in the second direction. good. With this configuration, each wiring from the light emitting element can be connected to the circuit as a whole, and the wiring can be easily routed.

  The circuit may be a drive circuit that drives the first light emitting element and the second light emitting element. In such a structure, a driver circuit can be provided near the light-emitting element, so that the wiring can be made relatively short. As a result, a signal with less dullness due to the stray capacitance of the wiring can be supplied to the light emitting element, and such a configuration is advantageous for a good latent image forming operation. Note that such a driving circuit can be formed of a TFT.

  However, the circuit is not limited to the drive circuit, and may be an FPC. That is, by disposing the FPC electrically connected to the wiring on one side in the second direction, the wiring from the light emitting element can be connected to the FPC as a whole, and the wiring can be easily routed. Become.

  In addition, the first light emitting element and the second light emitting element can be configured to emit light in accordance with the movement of the latent image carrier to form a latent image adjacent in the first direction. By arranging the first light emitting element and the second light emitting element in this way, the first light emitting element and the second light emitting element can be enlarged, and a latent image can be formed by forming a condensing portion with a sufficient amount of light. It is possible to execute well.

  Further, the width of the first light emitting element in the first direction may be longer than the distance between the first light emitting element and the second light emitting element in the first direction. This is because by using a light emitting element having such a size, a light condensing part can be formed with a large amount of light, and a good latent image can be formed.

  The second direction of the first latent image formed by the first light emitting element and the second latent image formed by the second light emitting element when the first light emitting element and the second light emitting element are caused to emit light simultaneously. The interval may be an integral multiple of the interval in the second direction of the pixels. When configured in this manner, the light condensing part can be appropriately formed for each pixel by causing each light emitting element to emit light at the same timing. Therefore, the control of the light emission timing of each light emitting element can be simplified.

  The present invention is preferably applied to a configuration in which the light emitting element is an organic EL element. This is because the organic EL element has a relatively small amount of light. Therefore, from the viewpoint of forming the light collecting section with a sufficient amount of light, it is preferable to apply the present invention, which is advantageous for increasing the light amount of the light emitting element by increasing the light emitting element, for such a configuration. Because there is. In particular, since a bottom emission type organic EL element has a small amount of light, it is preferable to apply the present invention to a configuration using a bottom emission type organic EL element as a light emitting element.

  Further, the latent image may be developed with a liquid developer. This is because the liquid developer can be developed with relatively high accuracy and is suitable for good image formation.

  In order to achieve the above object, an exposure head according to another aspect of the present invention includes a substrate having a plurality of light emitting elements grouped for each light emitting element group, and wiring connected to the light emitting elements, and a light emitting element group A lens in which a light beam emitted from the light emitting element is imaged as a spot and a spot latent image is formed on an image plane moving in a second direction orthogonal or substantially orthogonal to the first direction is provided for each light emitting element group The light emitting element group is provided with light emitting elements at positions different from each other in a direction corresponding to the first direction, and each light emitting element group emits a light beam in different exposure areas in the first direction. Two light emitting element groups that form a spot latent image and form a spot latent image in an exposure region adjacent to the first direction on the substrate correspond to the second direction. Each wiring provided in a direction shifted from each other and connected to light emitting elements belonging to the same light emitting element group is drawn out to the same side of the light emitting element group in a direction corresponding to the second direction. .

  In order to achieve the above object, the image forming apparatus according to the present invention is grouped for each light emitting element group and a latent image carrier whose surface moves in a second direction that is orthogonal or substantially orthogonal to the first direction. A lens having a plurality of light emitting elements and wiring connected to the light emitting elements, and a lens that forms a spot latent image on the surface of the latent image carrier by forming an image with the light beam emitted from the light emitting elements of the light emitting element group as a spot And an exposure head having a lens array provided for each light emitting element group. In the light emitting element group, each light emitting element is provided at a position different from each other in a direction corresponding to the first direction. The beam is emitted to form spot latent images in different exposure areas in the first direction, and the substrate forms spot latent images in the exposure areas adjacent to the first direction. The two light emitting element groups are arranged so as to be shifted from each other in the direction corresponding to the second direction, and each wiring connected to the light emitting elements belonging to the same light emitting element group is connected to the light emitting element group in the direction corresponding to the second direction. It is drawn out to the same side.

  In the invention thus configured (exposure head, image forming apparatus), the plurality of light emitting elements are provided in groups for each light emitting element group. In addition, two light emitting element groups that form a spot latent image in an exposure region adjacent in the first direction are provided so as to be shifted from each other in a direction corresponding to the second direction. As a result, since the light emitting element groups are discretely provided in the direction corresponding to the first direction, the light emitting element groups can be provided in a relatively wide space. Therefore, each light emitting element constituting the light emitting element group can be enlarged relatively easily, and a spot latent image can be formed with a sufficient amount of light.

  By the way, in the configuration in which a plurality of light emitting elements are grouped for each light emitting element group as described above, wirings connected to the light emitting element groups are drawn together for each light emitting element group from the viewpoint of simplifying the wiring pattern. It is desirable to be able to turn. On the other hand, in the present invention, each wiring connected to the light emitting elements belonging to the same light emitting element group is drawn out to the same side of the light emitting element group in a direction corresponding to the second direction. Therefore, according to the present invention, wirings for the same light emitting element group can be routed together on the substrate, and the wiring pattern can be simplified.

  Further, for each light emitting element belonging to the same light emitting element group, the wiring may be configured to be connected to the light emitting element from the drawing side of the wiring. In any case, with such a configuration, the wiring distance of each light emitting element can be shortened, and the wiring can be simplified.

  In addition, the wirings drawn from the light emitting element group are arranged in the direction corresponding to the first direction in the arrangement order in the direction corresponding to the first direction of the light emitting element group of the connection destination light emitting element. It may be configured. This is because the light emission control of each light emitting element can be simplified with such a configuration.

  Further, each light emitting element of the light emitting element group emits light at a timing according to the movement of the image plane, so that a plurality of spot latent images are formed side by side in the first direction, and the light emitting element group corresponds to the first direction. A plurality of light emitting element rows in which a plurality of light emitting elements are arranged in a direction corresponding to the second direction, and two light emitting elements that form a spot latent image adjacent to the first direction are different from each other. Each light emitting element row may be configured to be shifted from each other in a direction corresponding to the first direction so as to belong to the row. In such a configuration, two light emitting elements that form a spot latent image adjacent to each other in the first direction are shifted from each other in a direction corresponding to the second direction. Therefore, since the light emitting element can be formed in a relatively wide space, the size of the light emitting element can be increased. Therefore, a spot latent image can be formed with a sufficient amount of light, and a good spot latent image can be formed.

  Further, when the pitch in the direction corresponding to the first direction of the two light emitting elements that form the spot latent image adjacent to the first direction is the light emitting element pitch, the diameter of the light emitting element in the direction corresponding to the first direction. May be configured to be larger than the light emitting element pitch. This is because a spot latent image can be formed with a large amount of light by using a light emitting element having such a size, and a good spot latent image can be formed.

  In addition, when a plurality of spots formed by the light emitting element rows emitting in a row in the first direction are used as spot rows, the second of the plurality of spot rows formed on the image plane by simultaneous emission of the light emitting element groups. The light emitting element rows may be arranged so that the pitch in the direction is an integral multiple of the pixel pitch in the second direction. When configured in this way, a spot latent image can be appropriately formed for each pixel by causing each light emitting element row to emit light at the same timing. Therefore, the control of the light emission timing of each light emitting element can be simplified.

  Further, in the image forming apparatus using the above configuration that can form a spot latent image satisfactorily, the spot latent image may be developed with a liquid developer. That is, the liquid developer can perform latent image development with relatively high accuracy. Accordingly, it is preferable that the development of the spot latent image formed satisfactorily by the above-described invention is performed with the liquid developer.

A. Explanation of Terms Before explaining embodiments of the present invention, terms used in this specification will be explained.

  1 and 2 are explanatory diagrams of terms used in this specification. Here, the terms used in this specification will be organized using these drawings. In this specification, the transport direction of the surface (image surface IP) of the photosensitive drum 21 is defined as a sub-scanning direction SD, and a direction orthogonal or substantially orthogonal to the sub-scanning direction SD is defined as a main scanning direction MD. . The line head 29 is arranged with respect to the surface (image surface IP) of the photosensitive drum 21 so that the longitudinal direction LGD corresponds to the main scanning direction MD and the width direction LTD corresponds to the sub-scanning direction SD. Has been.

  A set of a plurality of (eight in FIG. 1 and FIG. 2) light emitting elements 2951 arranged on the head substrate 293 in a one-to-one correspondence with the plurality of lenses LS included in the lens array 299 is defined as a light emitting element group 295. To do. That is, in the head substrate 293, the light emitting element group 295 including the plurality of light emitting elements 2951 is disposed for each of the plurality of lenses LS. Further, the light beam from the light emitting element group 295 is imaged toward the image plane IP by the lens LS corresponding to the light emitting element group 295, whereby a set of a plurality of spots SP formed on the image plane IP is obtained. It is defined as group SG. That is, the plurality of spot groups SG can be formed in one-to-one correspondence with the plurality of light emitting element groups 295. In each spot group SG, the most upstream spot in the main scanning direction MD and the sub-scanning direction SD is particularly defined as the first spot. The light emitting element 2951 corresponding to the first spot is particularly defined as the first light emitting element.

  Further, as shown in the column “on image plane” in FIG. 2, a spot group row SGR and a spot group column SGC are defined. That is, a plurality of spot groups SG arranged in the main scanning direction MD are defined as spot group rows SGR. The plurality of spot group rows SGR are arranged side by side in the sub-scanning direction SD at a predetermined spot group row pitch Psgr. A plurality (three in the figure) of spot groups SG arranged at the spot group row pitch Psgr in the sub-scanning direction SD and at the spot group pitch Psg in the main scanning direction MD are defined as a spot group column SGC. The spot group row pitch Psgr is a distance in the sub-scanning direction SD between the geometric centroids of two spot group rows SGR adjacent to each other in the sub-scanning direction SD. The spot group pitch Psg is the distance in the main scanning direction MD of the geometric centroids of two spot groups SG adjacent to each other in the main scanning direction MD.

  Lens rows LSR and lens columns LSC are defined as shown in the “lens array” column of FIG. That is, a plurality of lenses LS arranged in the longitudinal direction LGD are defined as a lens row LSR. The plurality of lens rows LSR are arranged side by side in the width direction LTD at a predetermined lens row pitch Plsr. A plurality (three in the figure) of lenses LS arranged at the lens row pitch Plsr in the width direction LTD and at the lens pitch Pls in the longitudinal direction LGD are defined as a lens row LSC. The lens row pitch Plsr is a distance in the width direction LTD of the geometric centroids of two lens rows LSR adjacent to each other in the width direction LTD. The lens pitch Pls is a distance in the longitudinal direction LGD between the geometric centroids of the two lenses LS adjacent to each other in the longitudinal direction LGD.

  As shown in the column “Head Substrate” in the drawing, a light emitting element group row 295R and a light emitting element group column 295C are defined. That is, a plurality of light emitting element groups 295 arranged in the longitudinal direction LGD is defined as a light emitting element group row 295R. The plurality of light emitting element group rows 295R are arranged side by side in the width direction LTD at a predetermined light emitting element group row pitch Pegr. In addition, a plurality of (three in the figure) light emitting element groups 295 arranged at the light emitting element group row pitch Pegr in the width direction LTD and at the light emitting element group pitch Peg in the longitudinal direction LGD are defined as a light emitting element group column 295C. The light emitting element group row pitch Pegr is a distance in the width direction LTD between the geometric centroids of two light emitting element group rows 295R adjacent to each other in the width direction LTD. The light emitting element group pitch Peg is the distance in the longitudinal direction LGD between the geometric centers of gravity of two light emitting element groups 295 adjacent to each other in the longitudinal direction LGD.

  As shown in the “light emitting element group” column of FIG. 2, a light emitting element row 2951R and a light emitting element column 2951C are defined. That is, in each light emitting element group 295, a plurality of light emitting elements 2951 arranged in the longitudinal direction LGD is defined as a light emitting element row 2951R. The plurality of light emitting element rows 2951R are arranged side by side in the width direction LTD at a predetermined light emitting element row pitch Pelr. A plurality of (two in the figure) light emitting elements 2951 arranged in the width direction LTD at the light emitting element row pitch Pelr and at the longitudinal direction LGD in the longitudinal direction LGD are defined as a light emitting element row 2951C. The light emitting element row pitch Pelr is a distance in the width direction LTD of the geometric centroids of two light emitting element rows 2951R adjacent to each other in the width direction LTD. The light emitting element pitch Pel is a distance in the longitudinal direction LGD between the geometric centroids of two light emitting elements 2951 adjacent to each other in the longitudinal direction LGD.

  As shown in the column “Spot Group” in the figure, a spot row SPR and a spot column SPC are defined. That is, in each spot group SG, a plurality of spots SP arranged in the longitudinal direction LGD are defined as spot rows SPR. The plurality of spot rows SPR are arranged side by side in the width direction LTD at a predetermined spot row pitch Pspr. Further, a plurality of (two in the figure) spots arranged at the spot pitch Pspr in the width direction LTD and at the spot pitch Psp in the longitudinal direction LGD are defined as a spot row SPC. The spot row pitch Pspr is a distance in the sub-scanning direction SD between the geometric centroids of two spot rows SPR adjacent to each other in the sub-scanning direction SD. The spot pitch Psp is a distance in the longitudinal direction LGD between the geometric centroids of two spots SP adjacent to each other in the main scanning direction MD.

B. Embodiment FIG. 3 is a diagram showing an example of an image forming apparatus according to the present invention. FIG. 4 is a diagram showing an electrical configuration of the image forming apparatus of FIG. This apparatus uses a color mode in which four color toners of black (K), cyan (C), magenta (M), and yellow (Y) are superimposed to form a color image, and only black (K) toner. Thus, the image forming apparatus can selectively execute a monochrome mode for forming a monochrome image. FIG. 3 is a diagram corresponding to the execution of the color mode. In this image forming apparatus, when an image forming command is given from an external device such as a host computer to a main controller MC having a CPU, a memory, etc., the main controller MC gives a control signal to the engine controller EC and also outputs an image forming command. Corresponding video data VD is supplied to the head controller HC. The head controller HC controls the line head 29 for each color based on the video data VD from the main controller MC, the vertical synchronization signal Vsync from the engine controller EC, and parameter values. As a result, the engine unit EG executes a predetermined image forming operation, and forms an image corresponding to the image forming command on a sheet such as copy paper, transfer paper, paper, and an OHP transparent sheet.

  An electrical component box 5 containing a power circuit board, a main controller MC, an engine controller EC, and a head controller HC is provided in the housing main body 3 of the image forming apparatus. An image forming unit 7, a transfer belt unit 8, and a paper feed unit 11 are also disposed in the housing body 3. In FIG. 3, a secondary transfer unit 12, a fixing unit 13, and a sheet guide member 15 are disposed on the right side in the housing body 3. The paper feeding unit 11 is configured to be detachable from the apparatus main body 1. The paper feed unit 11 and the transfer belt unit 8 can be removed and repaired or exchanged.

  The image forming unit 7 includes four image forming stations Y (for yellow), M (for magenta), C (for cyan), and K (for black) that form a plurality of images of different colors. Each of the image forming stations Y, M, C, and K is provided with a cylindrical photosensitive drum 21 having a surface with a predetermined length in the main scanning direction MD. Each of the image forming stations Y, M, C, and K forms a corresponding color toner image on the surface of the photosensitive drum 21. The photosensitive drum is arranged so that the axial direction is substantially parallel to the main scanning direction MD. Each photosensitive drum 21 is connected to a dedicated drive motor and is driven to rotate at a predetermined speed in the direction of arrow D21 in the figure. As a result, the surface of the photosensitive drum 21 is conveyed in the sub-scanning direction SD that is orthogonal or substantially orthogonal to the main scanning direction MD. A charging unit 23, a line head 29, a developing unit 25, and a photoconductor cleaner 27 are disposed around the photoconductive drum 21 along the rotation direction. Then, a charging operation, a latent image forming operation, and a toner developing operation are executed by these functional units. Therefore, when the color mode is executed, the toner images formed at all the image forming stations Y, M, C, and K are superimposed on the transfer belt 81 of the transfer belt unit 8 to form a color image, and the monochrome mode is executed. In some cases, a monochrome image is formed using only the toner image formed at the image forming station K. In FIG. 3, the image forming stations of the image forming unit 7 have the same configuration, and therefore, for convenience of illustration, only some image forming stations are denoted by reference numerals, and the other image forming stations are omitted. .

  The charging unit 23 includes a charging roller whose surface is made of elastic rubber. The charging roller is configured to rotate in contact with the surface of the photosensitive drum 21 at the charging position, and at a peripheral speed in the driven direction with respect to the photosensitive drum 21 as the photosensitive drum 21 rotates. Followed rotation. The charging roller is connected to a charging bias generator (not shown). The charging roller is supplied with the charging bias from the charging bias generator and is charged at the charging position where the charging unit 23 and the photosensitive drum 21 come into contact with each other. The surface of 21 is charged.

  The line head 29 is disposed with respect to the photosensitive drum 21 such that the longitudinal direction thereof corresponds to the main scanning direction MD and the width direction thereof corresponds to the sub-scanning direction SD. Is substantially parallel to the main scanning direction MD. The line head 29 includes a plurality of light emitting elements arranged side by side in the longitudinal direction, and is spaced apart from the photosensitive drum 21. Then, light is emitted from these light emitting elements to the surface of the photosensitive drum 21 charged by the charging unit 23, and an electrostatic latent image is formed on the surface.

  The developing unit 25 has a developing roller 251 on which toner is carried. The charged toner is developed at a developing position where the developing roller 251 and the photosensitive drum 21 come into contact with each other by a developing bias applied to the developing roller 251 from a developing bias generator (not shown) electrically connected to the developing roller 251. Is moved from the developing roller 251 to the photosensitive drum 21, and the electrostatic latent image formed by the line head 29 becomes obvious.

  The toner image that has been made visible at the developing position in this way is conveyed in the rotational direction D21 of the photosensitive drum 21, and then a primary transfer position TR1 at which each of the photosensitive drums 21 comes into contact with the transfer belt 81, which will be described in detail later. 1 is primarily transferred to the transfer belt 81.

  In this embodiment, the photosensitive drum cleaner 27 is provided in contact with the surface of the photosensitive drum 21 on the downstream side of the primary transfer position TR1 in the rotational direction D21 of the photosensitive drum 21 and on the upstream side of the charging unit 23. It has been. The photoconductor cleaner 27 abuts on the surface of the photoconductor drum to clean and remove toner remaining on the surface of the photoconductor drum 21 after the primary transfer.

  The transfer belt unit 8 includes a driving roller 82, a driven roller 83 (blade facing roller) disposed on the left side of the driving roller 82 in FIG. 3, and a stretched direction of these rollers in the direction of the arrow D81 (conveying direction). And a transfer belt 81 that is driven to circulate. Further, the transfer belt unit 8 is disposed on the inner side of the transfer belt 81 so as to be opposed to each of the photosensitive drums 21 included in the image forming stations Y, M, C, and K when the photosensitive cartridge is mounted. Four primary transfer rollers 85Y, 85M, 85C, and 85K are provided. Each of these primary transfer rollers 85 is electrically connected to a primary transfer bias generator (not shown). As will be described in detail later, when the color mode is executed, as shown in FIG. 3, all the primary transfer rollers 85Y, 85M, 85C, 85K are positioned on the image forming stations Y, M, C, K side. Then, the transfer belt 81 is pushed and brought into contact with the photosensitive drums 21 included in the image forming stations Y, M, C, and K, so that the primary transfer position TR1 is set between each photosensitive drum 21 and the transfer belt 81. Form. Then, by applying a primary transfer bias from the primary transfer bias generator to the primary transfer roller 85 at an appropriate timing, the toner images formed on the surfaces of the photosensitive drums 21 correspond respectively. A color image is formed by transferring to the surface of the transfer belt 81 at the primary transfer position TR1.

  On the other hand, when the monochrome mode is executed, among the four primary transfer rollers 85, the color primary transfer rollers 85Y, 85M, and 85C are separated from the image forming stations Y, M, and C facing each other, and the monochrome primary transfer is performed. By bringing only the roller 85K into contact with the image forming station K, only the monochrome image forming station K is brought into contact with the transfer belt 81. As a result, the primary transfer position TR1 is formed only between the monochrome primary transfer roller 85K and the image forming station K. Then, by applying a primary transfer bias from the primary transfer bias generator to the monochrome primary transfer roller 85K at an appropriate timing, the toner image formed on the surface of each photosensitive drum 21 is subjected to primary transfer. A monochrome image is formed by transferring to the surface of the transfer belt 81 at a position TR1.

  Further, the transfer belt unit 8 includes a downstream guide roller 86 disposed on the downstream side of the monochrome primary transfer roller 85K and on the upstream side of the driving roller 82. Further, the downstream guide roller 86 is formed between the primary transfer roller 85K and the photosensitive drum 21 at the primary transfer position TR1 formed by the monochrome primary transfer roller 85K contacting the photosensitive drum 21 of the image forming station K. It is configured to contact the transfer belt 81 on a common inscribed line.

  The driving roller 82 circulates and drives the transfer belt 81 in the direction of the arrow D81 in the figure, and also serves as a backup roller for the secondary transfer roller 121. A rubber layer having a thickness of about 3 mm and a volume resistivity of 1000 kΩ · cm or less is formed on the peripheral surface of the driving roller 82, and secondary transfer is omitted by grounding through a metal shaft. The conductive path of the secondary transfer bias supplied from the bias generation unit via the secondary transfer roller 121 is used. When the rubber layer having high friction and shock absorption is provided on the driving roller 82 in this way, the sheet enters the contact portion (secondary transfer position TR2) between the driving roller 82 and the secondary transfer roller 121. Is difficult to be transmitted to the transfer belt 81, and image quality deterioration can be prevented.

  The sheet feeding unit 11 includes a sheet feeding unit having a sheet feeding cassette 77 capable of stacking and holding sheets and a pickup roller 79 that feeds sheets one by one from the sheet feeding cassette 77. The sheet fed from the sheet feeding unit by the pickup roller 79 is fed to the secondary transfer position TR2 along the sheet guide member 15 after the sheet feeding timing is adjusted by the registration roller pair 80.

  The secondary transfer roller 121 is provided so as to be able to come into contact with and separate from the transfer belt 81 and is driven to come into contact with and separate from a secondary transfer roller drive mechanism (not shown). The fixing unit 13 includes a heating roller 131 that includes a heating element such as a halogen heater and is rotatable, and a pressure unit 132 that presses and biases the heating roller 131. Then, the sheet on which the image is secondarily transferred is guided to a nip portion formed by the heating roller 131 and the pressure belt 1323 of the pressure portion 132 by the sheet guide member 15, and in the nip portion, a predetermined value is provided. The image is heat-fixed at temperature. The pressure unit 132 includes two rollers 1321 and 1322 and a pressure belt 1323 stretched between them. A nip portion formed by the heating roller 131 and the pressure belt 1323 by pressing the belt tension surface stretched by the two rollers 1321 and 1322 against the peripheral surface of the heating roller 131 among the surfaces of the pressure belt 1323. Is configured to be widely taken. Further, the sheet thus subjected to the fixing process is conveyed to a paper discharge tray 4 provided on the upper surface of the housing body 3.

  Further, in this apparatus, a cleaner portion 71 is disposed to face the blade facing roller 83. The cleaner unit 71 includes a cleaner blade 711 and a waste toner box 713. The cleaner blade 711 removes foreign matters such as toner and paper dust remaining on the transfer belt after the secondary transfer by bringing the tip of the cleaner blade 711 into contact with the blade facing roller 83 via the transfer belt 81. The foreign matter removed in this way is collected in a waste toner box 713. Further, the cleaner blade 711 and the waste toner box 713 are integrally formed with the blade facing roller 83. Therefore, when the blade facing roller 83 moves as will be described below, the cleaner blade 711 and the waste toner box 713 also move together with the blade facing roller 83.

  FIG. 5 is a perspective view showing an outline of the line head according to the present invention. FIG. 6 is a cross-sectional view in the width direction of the line head shown in FIG. As described above, the line head 29 is arranged with respect to the photosensitive drum 21 such that the longitudinal direction LGD corresponds to the main scanning direction MD and the width direction LTD corresponds to the sub-scanning direction SD. The longitudinal direction LGD and the width direction LTD are substantially orthogonal to each other. The line head 29 includes a case 291, and positioning pins 2911 and screw insertion holes 2912 are provided at both ends of the case 291 in the longitudinal direction LGD. Then, the positioning pin 2911 covers the photosensitive drum 21 and is fitted into a positioning hole (not shown) formed in a photosensitive cover (not shown) positioned with respect to the photosensitive drum 21, thereby The head 29 is positioned with respect to the photosensitive drum 21. Further, the line head 29 is positioned and fixed with respect to the photosensitive drum 21 by screwing and fixing a fixing screw into a screw hole (not shown) of the photosensitive member cover through the screw insertion hole 2912.

  The case 291 holds the lens array 299 at a position facing the surface of the photosensitive drum 21, and includes a light shielding member 297 and a head substrate 293 in the order close to the lens array 299. The head substrate 293 is formed of a material (for example, glass) that can transmit a light beam. A plurality of bottom emission organic EL (Electro-Luminescence) elements are arranged as light emitting elements 2951 on the back surface of the head substrate 293 (the surface opposite to the lens array 299 of the two surfaces of the head substrate 293). ing. The plurality of light emitting elements 2951 are arranged in groups for each light emitting element group 295, as will be described later. The light beams emitted from the respective light emitting element groups 295 are transmitted from the back surface to the front surface of the head substrate 293 and directed to the light shielding member 297.

  A plurality of light guide holes 2971 are formed in the light shielding member 297 on a one-to-one basis with respect to the plurality of light emitting element groups 295. Further, the light guide hole 2971 is formed as a substantially cylindrical hole penetrating the light shielding member 297 with a line parallel to the normal line of the head substrate 293 as a central axis. Therefore, among the light beams emitted from the light emitting element group 295, the light beams that are directed to other than the light guide hole 2971 corresponding to the light emitting element group 295 are blocked by the light blocking member 297. Thus, all the light emitted from one light emitting element group 295 is directed to the lens array 299 through the same light guide hole 2971, and interference between light beams emitted from different light emitting element groups 295 is prevented by the light shielding member 297. The Then, the light beam that has passed through the light guide hole 2971 formed in the light shielding member 297 is imaged as a spot on the surface of the photosensitive drum 21 by the lens array 299.

  As shown in FIG. 6, the back cover 2913 is pressed against the case 291 via the head substrate 293 by the fixing device 2914. That is, the fixing device 2914 has an elastic force that presses the back cover 2913 toward the case 291, and presses the back cover with the elastic force, thereby making the inside of the case 291 light-tight (that is, from the inside of the case 291. It is sealed so that light does not leak and so that light does not enter from the outside of the case 291. Note that a plurality of fixing devices 2914 are provided in the longitudinal direction of the case 291. The light emitting element group 295 is covered with a sealing member 294.

  FIG. 7 is a perspective view schematically showing the lens array. FIG. 8 is a cross-sectional view of the lens array in the longitudinal direction LGD. The lens array 299 has a lens substrate 2991. The first surface LSFf of the lens LS is formed on the back surface 2991B of the lens substrate 2991, and the second surface LSFs of the lens LS is formed on the surface 2991A of the lens substrate 2991. The first surface LSFf and the second surface LSFs of the lenses facing each other and the lens substrate 2991 sandwiched between these two surfaces function as one lens LS. The first surface LSFf and the second surface LSFs of the lens LS can be formed of, for example, a resin.

  In the lens array 299, a plurality of lenses LS are arranged so that their optical axes OA are substantially parallel to each other. The lens array 299 is arranged so that the optical axis OA of the lens LS is substantially orthogonal to the back surface of the head substrate 293 (the surface on which the light emitting element 2951 is disposed). The lenses LS are provided one-on-one with respect to the light emitting element group 295, and a plurality of lenses LS are two-dimensionally arranged corresponding to the arrangement of the light emitting element groups 295 described later. That is, a plurality of lens rows LSC in which three lenses LS are arranged at different positions in the width direction LTD are arranged along the longitudinal direction LGD.

  FIG. 9 is a diagram showing the configuration of the back surface of the head substrate, which corresponds to the case where the back surface is viewed from the front surface of the head substrate. In FIG. 9, the lens LS is indicated by a two-dot chain line. This is for indicating that the light emitting element groups 295 are provided in one-to-one relationship with the lens LS. It does not indicate that it is arranged on the back surface of the head substrate. As shown in FIG. 9, a plurality of light emitting element group columns 295C in which three light emitting element groups 295 are arranged at different positions in the width direction LTD are arranged in the longitudinal direction LGD. In other words, the light emitting element group row 295R in which a plurality of light emitting element groups 295 are arranged along the longitudinal direction LGD is arranged in three rows (295R_A, 295R_B, 295R_C) in the width direction LTD. At this time, the light emitting element group rows 295R are arranged so as to be shifted from each other in the longitudinal direction LGD so that the positions of the light emitting element groups 295 are different from each other in the longitudinal direction LGD. In this embodiment, since the light emitting element groups 295 are arranged in this way, each light emitting element group 295 forms a spot latent image in different exposure areas in the main scanning direction MD as will be described in detail later with reference to FIG. Form. In addition, the light emitting element groups 295 (for example, the light emitting element groups 295_1 and 295_2 or the light emitting element groups 295_2 and 295_3) that form a spot latent image in the exposure region adjacent to the main scanning direction MD are arranged so as to be shifted from each other in the width direction LTD. Is done.

  FIG. 10 is a plan view showing the structure of the light emitting element group. The column “Light emitting element group” in FIG. 10 mainly shows the relationship between the light emitting element group 295 and the light emitting element group and the wiring WL. The column of “element” mainly shows the relationship between the light emitting element and the wiring WL. As shown in the figure, two light emitting element rows 2951R in which four light emitting elements 2951 are arranged in the longitudinal direction LGD are arranged in the width direction LTD. The respective light emitting element rows 2951R are arranged so as to be shifted from each other by the light emitting element pitch Pel in the longitudinal direction LGD, and the respective light emitting elements 2951 are located at different positions in the longitudinal direction LGD. Accordingly, as will be described later with reference to FIG. 17 and the like, the respective light emitting elements 2951_1 to 2951_8 emit light at a timing according to the movement of the surface of the photosensitive drum 21, and are arranged in the main scanning direction MD along the spot latent images Lsp_1 to Lsp8. Is formed. In addition, the spot latent images adjacent in the main scanning direction MD are formed by the light emitting elements 2951 (for example, the light emitting elements 2951_1 and 2951_2 in the figure) belonging to different light emitting element rows 2951R. Here, the “light emitting element pitch Pel” corresponds to a pitch in the longitudinal direction LGD of two light emitting elements 2951 (for example, light emitting elements 2951_7 and 2951_8) that form a spot latent image adjacent to the main scanning direction MD.

  A wiring WL is connected to each light emitting element 2951 of the light emitting element group 295. For example, a wiring WL_1 is connected to the light emitting element 2951_1, and a wiring WL_2 is connected to the light emitting element 2951_2. In addition, these wirings WL are all drawn out to one side (hereinafter, simply referred to as “one side”) of the light emitting element group 295 in the width direction LTD. More specifically, each of the wirings WL_1 to WL_8 is connected to the light emitting element 2951 from the drawing side (one side) of the wiring WL, and each of the wirings WL_1 to WL_8 is directly drawn out to one side of the light emitting element group 295. (Refer to the column of “light emitting element group” in the figure).

  In addition, the wirings WL_1 to WL_8 drawn from the light emitting element group 295 are arranged in the longitudinal direction LGD in the arrangement order in the longitudinal direction LGD in the light emitting element group 295 of the connected light emitting element 2951. That is, as shown in the column of “light emitting element group” in the drawing, eight light emitting elements 2951 are provided in the longitudinal direction LGD in the arrangement order of the light emitting elements 2951_1 to 2951_8n, and the wirings WL_1 to WL_8 are also provided. They are provided in the longitudinal direction LGD according to the arrangement order of the light emitting elements 2951 to be connected, and are arranged in the longitudinal direction LGD in the order of the wirings WL_1 to WL_8.

  In the present embodiment, the diameter Del in the longitudinal direction LGD of the light emitting element 2951 is set larger than the light emitting element pitch Pel (interval) so that the light quantity of the light emitting element 2951 is sufficiently secured.

  Corresponding to each light emitting element group row 295R_A, 295R_B, 295R_C, driving circuits DC_A (for each light emitting element group row 295R_A), DC_B (for each light emitting element group row 295R_B), DC_C (for each light emitting element group row 295R_C) are provided. These drive circuits DC_A and the like are configured by, for example, TFTs (Thin Film Transistors) (FIG. 13). When the drive circuit DC_A or the like gives a drive signal to each light emitting element 2951, each light emitting element 2951 emits light beams having the same wavelength. The light emitting surface of the light emitting element 2951 is a so-called perfect diffusion surface light source, and the light beam emitted from the light emitting surface follows Lambert's cosine law.

  The driving operation of the driving circuit DC is controlled based on the video data VD. That is, when the main controller MC receives the vertical request signal VREQ from the head controller HC, it generates video data VD for one page (FIG. 4). Each time the main controller MC receives the horizontal request signal HREQ from the head controller HC, the video data VD is transmitted to the head controller HC line by line. Then, the head controller HC controls the drive circuit DC based on the received video data VD. Next, a specific configuration for realizing these control operations will be described.

  In the present embodiment, the above signals, that is, the request signals VREQ and HREQ sent from the head controller HC to the main controller MC and the video data VD sent from the main controller MC to the head controller HC correspond to each color of YMCK. There are 4 sets. In the following, the colors are distinguished by attaching a hyphen and a code representing the color to each signal as necessary. For example, the vertical request signal, horizontal request signal, and video data for yellow are represented as VREQ-Y, HREQ-Y, and VD-Y, respectively.

  FIG. 11 is a block diagram showing the configuration of the main controller. The main controller MC includes an image processing unit 51 that performs signal processing necessary for image data included in an image formation command given from an external device, and a main-side communication module 52. The image processing unit 51 is provided with a color conversion processing block 511 that develops RGB image data into CMYK image data corresponding to each toner color. Further, the image processing unit 51 is provided with image processing blocks 512Y (for yellow), 512M (for magenta), 512C (for cyan), and 512K (for black) corresponding to each toner color. Is processed as follows. That is, in the image processing block 512Y and the like, the image data is bitmap-developed in accordance with the resolution of the line head 29, and screen processing, gamma correction, etc. are performed on the data after the bitmap development, and the video data VD-Y and the like are generated. In this way, the image data is converted into information having a pixel as a minimum unit. Here, the pixel is a minimum unit constituting an image formed by the line head 29. This series of signal processing is executed for one page of image for each input of the vertical request signal VREQ-Y, and the generated video data VD-Y for each line is sequentially output to the main communication module 52.

  In the main communication module 52, the four colors of video data VD-Y, VD-M, VD-C, and VD-K output from the image processing unit 51 are time-division multiplexed and multiplexed video data VD is serially transmitted to the head controller HC via the differential output terminals TX + and TX−. On the other hand, the vertical request signals VREQ-Y, VREQ-M, VREQ-C, VREQ-K and horizontal request signals HREQ-Y, HREQ time-division multiplexed from the head controller HC via the differential input terminals RX +, RX-. -M, HREQ-C, and HREQ-K are input. These request signals VREQ and HREQ are developed in parallel, and vertical request signals VREQ (VREQ-Y, etc.) for each color are input to the corresponding color image processing block 512 (512Y, etc.).

  FIG. 12 is a block diagram showing the configuration of the head controller. The head controller HC includes a head side communication module 53 and a head control module 54. In the head side communication module 53, request signals of four colors output from the head control module 54, that is, vertical request signals VREQ-Y, VREQ-M, VREQ-C, VREQ-K and horizontal request signals HREQ-Y, HREQ. -M, HREQ-C, and HREQ-K are time-division multiplexed. The time-division multiplexed request signal is serially transmitted to the main controller MC via the differential output terminals TX + and TX−. On the other hand, video data VD-Y, VD-M, VD-C, and VD-K that are time-division multiplexed are input from the main controller MC via the differential input terminals RX + and RX-. These video data VD-Y and the like are developed in parallel and input to the corresponding color head control block 541Y and the like.

  In the head control module 54, four sets of head control blocks 541Y (for yellow), 514M (for magenta), 514C (for cyan), and 514K (for black) are provided corresponding to each color. The head control block 541Y etc. outputs each request signal VREQ-Y, HREQ-Y etc. to request the video data VD-Y etc., while the corresponding color line head based on the received video data VD-Y etc. 29 exposure operations are controlled.

  FIG. 13 is a block diagram showing the configuration of the head control block in this embodiment. Here, the Y head control block 541Y for yellow will be described, but the other blocks 541M, 541C, and 541K have the same structure. The Y head control block 410Y is provided with a request signal generation unit 542 that generates request signals VREQ-Y and HREQ-Y based on a synchronization signal Vsync supplied from the engine controller EC. The request signal generation unit 542 starts counting an internal timer when receiving the synchronization signal Vsync, and outputs a vertical request signal VREQ-Y indicating the head of the page when a predetermined waiting time has elapsed. Subsequent to the output of the vertical request signal VREQ-Y, the request signal generation unit 542 repeatedly outputs the horizontal request signals HREQ-Y corresponding to the number of lines constituting one page image at a constant cycle. These request signals VREQ-Y and HREQ-Y are sent to the head-side communication module 53, and are time-division multiplexed together with request signals of other colors and transmitted to the main controller MC.

  The horizontal request signal HREQ-Y is also input to the divided HREQ signal generation unit 543, and the divided HREQ signal generation unit 543 generates the divided HREQ signal by multiplying the input request signal HREQ-Y by 16 times, for example. To do. The divided HREQ signal is input to the light emission order control unit 544, and the light emission order control unit 544 rearranges the video data VD-Y based on the divided HREQ signal. Such data rearrangement rearranges the video data VD-Y received line by line from the top of the page in the order of transmission to the drive circuit DC_A or the like.

  That is, as will be described later, each light emitting element group row 295R forms a spot group SG at a position shifted from each other in the sub-scanning direction SD by the sub-scanning spot group pitch Psgs (FIGS. 14 to 16, etc.). Therefore, in order to form the spot latent images for one line side by side in the main scanning direction MD, the video data VD-Y is transmitted to the drive circuit DC_A and the like in consideration of the difference in the formation position of the spot group SG. There is a need to. Specifically, when the value obtained by dividing the sub-scanning spot group pitch Psgs by the sub-scanning pixel pitch Rsd is defined as “the number of delay lines”, the delay in the sub-scanning direction SD for each light emitting element group row 295R_A and the like. The video data VD-Y is rearranged so that the video data VD-Y shifted from each other by the number of lines is transmitted at the same transmission timing. For example, at the timing when the video data VD-Y of the first line is transmitted to the light emitting element group row 295R_A, the video data of the 161st line (= 1 line + number of delay lines) is transmitted to the light emitting element group row 295R_B. VD-Y is transmitted, and video data VD-Y of the 321st line (= 1 line + 2 × number of delay lines) is transmitted to the light emitting element group row 295R_C.

  The output buffer 545 supplies the video data VD-Y thus rearranged to the respective drive circuits DC_A, DC_B, and DC_C through the data transfer line. These output buffers 545 are constituted by, for example, shift registers, and the data transfer line connected from the output buffer 545 to each drive circuit DC_A and the like is shared between the drive circuits. Then, the drive circuit DC_A and the like drive and emit light from the light emitting element 2951 based on the video data VD-Y supplied from the output buffer 545. At this time, drive light emission of the drive circuit DC_A and the like is performed in synchronization with a light emission switching timing Tu supplied from a light emission timing generation unit 546 described below.

  The divided HREQ signal is also input to the light emission timing generation unit 546, and the light emission timing generation unit 546 generates the light emission switching timing Tu based on the divided HREQ signal. The light emission timing generation unit 546 is connected to each drive circuit DC_A and the like via one light emission timing control line LTu, and each light emission timing control line LTu is shared between the drive circuits. The light emission timing generation unit 546 supplies the light emission switching timing Tu to each drive circuit DC_A and the like via the light emission timing control line LTu. The drive circuits DC_A and the like drive and emit the light emitting elements 2951 such as the corresponding light emitting element group row 295R_A based on the video data VD-Y supplied in advance at the light emission switching timing Tu. Thus, by controlling the driving light emission of the light emitting element 2951 at the light emission switching timing Tu, each spot SP can be formed on the pixel PX on the surface of the photosensitive drum. Therefore, the spot forming operation will be described below.

  FIG. 14 is a perspective view for explaining the spot forming operation, and FIG. 15 is a diagram showing spot groups formed on the surface of the photosensitive drum at the light emission switching timing Tu in the present embodiment. In FIG. 14, the description of the lens array 299 is omitted. Here, after first explaining the relationship between the spot group SG and the pixel PX, the spot formation at the light emission switching timing Tu will be explained.

  As shown in FIG. 14, each light emitting element group 295 can form spot groups SG in different exposure regions ER in the main scanning direction MD. Here, the spot group SG is a set of a plurality of spots SP formed by simultaneously emitting light from all the light emitting elements 2951 of the light emitting element group 295. In addition, a spot latent image is formed in a range where the spot SP is formed and exposed by the spot. In the present embodiment, two light emitting element groups 295 (for example, the light emitting element groups 295_1 and 295_2 or the light emitting element groups 295_2 and 295_3) that form a spot latent image in the exposure region ER adjacent to the main scanning direction MD are They are shifted from each other in the width direction LTD. Specifically, the three light emitting element groups 295 capable of forming the spot group SG in the exposure region ER continuous in the main scanning direction MD are arranged so as to be shifted from each other in the width direction LTD. That is, for example, the three light emitting element groups 295_1, 295_2, 295_3 capable of forming the spot groups SG_1, SG2, SG3 in the exposure regions ER_1, ER_2, ER3 continuous in the main scanning direction MD are mutually connected in the width direction LTD. They are staggered. The three light emitting element groups 295 constitute a light emitting element group column 295C, and a plurality of light emitting element group columns 295C are arranged along the longitudinal direction LGD.

  As shown by a broken line in FIG. 15, a plurality of pixels PX are virtually provided on the surface of the photosensitive drum 21, and one line of pixels PX arranged in the main scanning direction MD is sub-scanning. A plurality of lines are arranged in the direction SD. The pitch between adjacent pixels in the main scanning direction MD is the main scanning pixel pitch Rmd, and the pitch between adjacent pixels in the sub scanning direction SD is the sub scanning pixel pitch Rsd. In these drawings, the main scanning resolution and the sub scanning resolution are both 600 dpi (dot per inch), and the main scanning pixel pitch Rmd and the sub scanning pixel pitch Rsd are equal to each other. Here, the resolution is the pixel density and represents the number of pixels per inch.

  By the way, the pixel pitch on the surface of the photosensitive drum can be obtained from, for example, the pixel pitch of the image formed on the paper. However, in the sub-scanning direction SD, the moving speed of the surface of the photosensitive drum and the conveyance speed of the paper may be slightly different. In this case, the sub-scanning pixel pitch is different between the surface of the photosensitive drum and the paper. Therefore, when obtaining the sub-scanning pixel pitch on the surface of the photosensitive drum from the image formed on the paper, the sub-scan obtained from the image on the paper is obtained by calculating the speed ratio between the moving speed of the surface of the photosensitive drum and the conveyance speed of the paper The pixel pitch may be multiplied. As the speed ratio, for example, a value described in the specification of an image forming apparatus such as a printer can be used.

  As shown in FIGS. 14 and 15, in each spot group SG, two spot rows SPRa and SPRb are arranged at a spot row pitch Pspr in the sub-scanning direction SD. In FIG. 15, symbols SPRa and SPRb are attached to the spot rows, but the spot rows with the same symbols are positioned in the sub-scanning direction SD within the spot group SG (intra-group sub-scanning position). Are equal to each other. Here, the “intra-group sub-scanning position” is a position in the sub-scanning direction SD of the object (spot or spot row) with respect to the MD-SD coordinate axis provided for each spot group SG. For example, in FIG. The intra-group sub-scanning position of the spot SP is the position Psd1, and the intra-group sub-scanning position of the spot row SPR is the position Psd2. FIG. 16 is an explanatory diagram of the intra-group sub-scanning position.

  In this embodiment, the spot row pitch Pspr is set to an integral multiple (1 times) of the sub-scanning pixel pitch Rsd (FIG. 15). Further, spot groups SG formed by different light emitting element group rows 295R are at different positions in the sub-scanning direction SD, and the pitch in the sub-scanning direction SD (sub-scanning spot group pitch Psgs) between these spot groups SG. ) Is set to an integral multiple (160 times) of the sub-scanning pixel pitch Rsd. In the present embodiment, the pitch Pegr between the light emitting element groups in the longitudinal direction LTD and the pitch Plsr between the lenses LS in the longitudinal direction LTD are equal to each other, and are an integral multiple (160 times) of the sub-scanning pixel pitch. In addition, the line head 29 is configured. That is, by configuring the line head 29 in this way, the sub-scanning spot group pitch Psgs can be easily set to an integral multiple of the sub-scanning pixel pitch Rsd.

  Thus, in the line head of this embodiment, the sub-scanning spot group pitch Psgs is set to an integral multiple of the sub-scanning pixel pitch Rsd. Moreover, in this embodiment, in each spot group SG, the pitch between spots SP formed at different positions in the sub-scanning direction SD is set to an integral multiple (1 times) of the sub-scanning pixel pitch Rsd. . That is, the pitch Pspr in the sub-scanning direction SD between the spot rows SPRa and SPRb along the sub-scanning direction SD is set to an integral multiple (1 times) of the sub-scanning pixel pitch Rsd.

  Therefore, in this embodiment, all the spots SP can be formed on the pixel PX at the same time at the light emission switching timing Tu. Therefore, the spot SP can be appropriately formed in each pixel PX only by controlling all the light emitting elements 2951 at the same light emission switching timing Tu, and the light emission switching timing control is simplified. Further, since all the light emitting elements 2951 can be controlled at the same light emission switching timing Tu, one light emission timing control line LTu can be used in common among all the light emitting element group rows 295R_A, 295R_B, 295R_C. The configuration of the line head 29 is simplified (FIG. 13).

  In the present embodiment, the light emitting elements 2951 of the light emitting element group emit light at the light emission timing Tu while the surface of the photosensitive drum 21 moves in the sub scanning direction SD, and thereby a plurality of spots arranged in the main scanning direction MD. A latent image Lsp is formed.

  FIG. 17 is a diagram showing an example of the spot latent image forming operation. As shown in the column of “first light emission switching timing Tu” in the drawing, each light emitting element 2951_1, 2951_3, 2951_5, 2951_7 (first light emitting element) of the light emitting element row 2951Ra (FIG. 10) is changed at the light emission switching timing Tu. When each spot SP of the spot row SPRa is formed by driving light emission, spot latent images Lsp_1, Lsp_3, Lsp_5, and Lsp_7 (first latent image) are formed for each pixel PX. Next, when the surface of the photosensitive drum 21 moves by a distance corresponding to one time of the sub-scanning pixel pitch Rsd (interval), the light emitting elements 2951_2, 2951_4, and 2951_6 in the light emitting element row 2951Rb at the second light emission switching timing Tu. , 2951_8 (second light emitting element) is driven to emit light. Thereby, each spot SP of the spot row SPRb is formed, and spot latent images Lsp_2, Lsp_4, Lsp_6, and Lsp_8 (second latent image) are formed for each pixel PX. In this way, each of the light emitting elements 2951 emits light according to the movement of the surface of the photosensitive drum, whereby a plurality of spot latent images Lsp arranged in the main scanning direction MD can be formed. Thus, in this embodiment, a spot latent image (adjacent spot latent image) is formed adjacent to the main scanning direction MD by two light emitting elements 2951 belonging to different light emitting element rows 2951R. That is, for example, of the two light emitting elements 2951R_1 and 2951R_2 that form the adjacent spot latent images Lsp1 and Lsp2, the light emitting element 2951R_1 belongs to the light emitting element row 2951R_A, and the light emitting element 2951R_2 belongs to the light emitting element row 2951R_B.

  Thus, in the above embodiment, the plurality of light emitting elements 2951 are provided in groups for each light emitting element group 295. In addition, two light emitting element groups 295 that form a spot latent image in the exposure region ER adjacent to the main scanning direction MD are provided so as to be shifted from each other in the width direction LTD. As a result, as shown in FIG. 9, since the light emitting element groups 295 are provided discretely in the longitudinal direction LGD, the light emitting element groups 295 can be provided in a relatively wide space. Therefore, each light emitting element 2951 constituting the light emitting element group 295 can be enlarged relatively easily, and a spot latent image can be formed with a sufficient amount of light.

  Furthermore, in the above embodiment, each wiring WL connected to the light emitting elements 2951 belonging to the same light emitting element group 295 is drawn out to the same side (one side in the above embodiment) of the light emitting element group in the width direction LTD. (FIG. 10). Therefore, in this embodiment, the wirings WL for the same light emitting element group 295 can be routed together on the head substrate 293, and the wiring pattern can be simplified.

  In addition, by drawing each wiring WL to the same side of the light emitting element group in this way, the wiring distance to each light emitting element 2951 can be easily made substantially the same. Therefore, the line head 29 of the above-described embodiment is advantageous for suppressing a variation in the light emission characteristics of each light emitting element 2951 and performing a good spot latent image.

  Further, in the above embodiment, for each light emitting element 2951 belonging to the same light emitting element group 295, the wiring WL is connected to the light emitting element 2951 from the drawing side of the wiring WL. In such a connection mode of the wiring WL, for example, the wiring distance is shortened compared to the case where the wiring WL is connected to the light emitting element 2951 from the opposite side (the “other side” in FIG. 10) of the wiring WL. be able to. As a result, the wiring WL can be simplified.

  In the above embodiment, the wirings WL drawn from the light emitting element group 295 are arranged in the longitudinal direction LGD in the arrangement order in the longitudinal direction LGD of the light emitting element group 295 of the connection destination light emitting element 2951. The light emission control of each light emitting element 2951 is simplified. That is, the drive circuit DC_A or the like provides a drive signal to each light emitting element 2951 through the wiring WL. At this time, in order to appropriately form a spot latent image, it is necessary to accurately supply a drive signal to the light emitting element 2951 corresponding to the pixel on which the spot latent image is to be formed. However, if the arrangement of the extracted wirings WL is different regardless of the arrangement order of the light emitting elements 2951, it is necessary to perform control such as rearranging the video data VD corresponding to such a wiring mode. there is a possibility. On the other hand, in the above embodiment, the wirings WL are arranged in the longitudinal direction LGD in the arrangement order of the light emitting elements 2951. Therefore, control such as rearrangement of the video data VD as described above can be omitted, and the light emission control of the light emitting element 2951 can be simplified.

  Further, in the above embodiment, the light emitting element rows 2951 are shifted from each other in the longitudinal direction LGD so that the two light emitting elements 2951 forming the spot latent image adjacent to the main scanning direction MD belong to different light emitting element rows 2951R. ing. In other words, the two light emitting elements 2951 that form a spot latent image adjacent to the main scanning direction MD are shifted from each other in the width direction LTD. Therefore, the inter-element space BE between the light emitting elements arranged in the longitudinal direction LGD in the light emitting element row 2951R can be made relatively large (FIG. 10). Therefore, since the light-emitting element 2951 can be formed in a relatively wide space, the size of the light-emitting element 2951 can be increased. As a result, a spot latent image can be formed with a sufficient amount of light even at a high resolution, and a good spot latent image can be formed.

  In the above embodiment, an organic EL element is used as the light emitting element 2951. This organic EL element has a small amount of light compared to, for example, an LED (Light Emitting Diode) or the like. Therefore, it is particularly preferable to apply the present invention in which the size of the light emitting element 2951 can be increased for a configuration using an organic EL element. In particular, since the bottom emission type organic EL element has a small amount of light as in the above embodiment, it is preferable to apply the present invention to the configuration using the bottom emission type organic EL element as the light emitting element 2951. is there.

  Thus, in the above embodiment, the main scanning direction MD and the longitudinal direction LGD correspond to the “first direction” of the present invention, the sub-scanning direction SD and the width direction LTD correspond to the “second direction” of the present invention, The photosensitive drum 21 corresponds to the “latent image carrier” of the invention, the surface of the photosensitive drum 21 corresponds to the “image plane” of the invention, and the head substrate 293 corresponds to the “substrate” of the invention. Yes. The line head 29 corresponds to the “exposure head” of the present invention, the lens LS corresponds to the “imaging optical system” of the present invention, and the spot SP corresponds to the “condensing part” of the present invention.

Others The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, in the above embodiment, the light emitting element group 295 is composed of two light emitting element rows 2951R arranged in the width direction LTD. However, the number of light emitting element rows 2951R is not limited to two and can be changed as necessary. Further, the number of the light emitting elements 2951 constituting each light emitting element row 2951R can be changed as necessary. Specifically, for example, the following changes are possible.

  FIG. 18 is a plan view showing another configuration of the light emitting element group. In the same figure, in order to show the relationship between the light emitting element group 295 and the lens LS, the lens LS is shown with the dashed-two dotted line. In the light emitting element group 295, four light emitting element rows 2951R in which five light emitting elements 2951 are arranged in the longitudinal direction LGD are arranged in the width direction LTD. Each light emitting element row 2951R is arranged so as to be shifted from each other in the width direction LTD, and each light emitting element 2951 is located at a different position in the width direction LTD. Each light emitting element row 2951R emits light at a timing according to the movement of the surface of the photosensitive drum 21, and a plurality of spot latent images arranged in the main scanning direction MD can be formed.

  All the wirings WL connected to the respective light emitting elements 2951 of the light emitting element group 295 are drawn out to one side of the light emitting element group 295 in the width direction LTD. In particular, in the figure, each wiring WL is drawn to the outside of the lens LS. In addition, each wiring WL is connected to the light emitting element 2951 from the drawing side (one side) of the wiring WL. These wirings WL drawn from the light emitting element group 295 are arranged in the longitudinal direction LGD in the arrangement order in the longitudinal direction LGD in the light emitting element group 295 of the connected light emitting element 2951.

  As described above, also in another configuration illustrated in FIG. 18, each wiring WL connected to the light emitting elements 2951 belonging to the same light emitting element group 295 has the same side of the light emitting element group in the width direction LTD (in the above embodiment, One side). Accordingly, the wirings WL for the light emitting element group 295 can be collectively routed on the head substrate 293, and the wiring pattern can be simplified. Also in this other configuration, the respective wirings WL are arranged in the arrangement order of the light emitting elements 2951 so that the light emission control of the light emitting elements 2951 is simplified.

  In the above embodiment, each wiring WL is connected to the light emitting element 2951 from the drawing side (one side) of the wiring WL, but the wiring WL may be connected to the light emitting element 2951 as follows. FIG. 19 is a plan view showing still another configuration of the light emitting element group. In the light emitting element group 295, two light emitting element rows 2951R in which six light emitting elements 2951 are arranged in the longitudinal direction LGD are arranged in the width direction LTD. Each light emitting element row 2951R is arranged so as to be shifted from each other in the width direction LTD, and each light emitting element 2951 is located at a different position in the width direction LTD. Each light emitting element row 2951R emits light at a timing according to the movement of the surface of the photosensitive drum 21, and a plurality of spot latent images arranged in the main scanning direction MD can be formed.

  In addition, all the wirings WL connected to the respective light emitting elements 2951 of the light emitting element group 295 are drawn out to one side of the light emitting element group 295 in the width direction LTD. In this respect, another configuration of the light emitting element group shown in FIG. 19 is common to the embodiment described above. However, the configuration shown in the figure differs from the embodiment described above in the way in which the wiring WL is connected to the light emitting element 2951. In other words, in the configuration shown in the figure, the wiring WL for the light emitting elements 2951_4, 2951_6, 2951_8, and 2951_10 is connected to the light emitting element from the opposite side (the other side) of the wiring WL to the drawing side.

  As described above, also in another configuration shown in FIG. 19, each wiring WL connected to the light emitting elements 2951 belonging to the same light emitting element group 295 is connected to the same side of the light emitting element group in the width direction LTD (the above embodiment). Then it is pulled out to one side). Accordingly, the wirings WL for the light emitting element group 295 can be collectively routed on the head substrate 293, and the wiring pattern can be simplified. In the still another structure shown in FIG. 19, the wiring WL does not pass between the light emitting elements 2951 in one row of the light emitting element group 295 as in the structure shown in FIG. The size can be made larger.

  Moreover, it can also comprise as shown in FIGS. 20 to 22 are plan views showing modifications of the light emitting element group and the wiring connected to the light emitting element group. These drawings show the configuration of the back surface of the head substrate 293 as viewed from the front surface side of the head substrate 293. In these drawings, the lens LS is indicated by a two-dot chain line, but this indicates the positional relationship between the light emitting element group 295 and the lens LS in plan view, and the lens LS is disposed on the back surface of the head substrate 293. It does not indicate that it is.

  First, the modification shown in FIG. 20 will be described. In the modification shown in the figure, six light emitting elements 2951 are arranged in a straight line in the longitudinal direction LGD to form a light emitting element row 2951R. In the light emitting element group 295, three light emitting element rows 2951R are arranged at different positions in the width direction LTD. Each light emitting element row 2951R is mutually shifted by the light emitting element pitch Pel in the longitudinal direction LGD, and the position of each light emitting element 2951 is different from each other in the longitudinal direction LGD. In addition, the diameter Del of the longitudinal direction LGD (width of the longitudinal direction LGD) of each light emitting element 2951 is wider than the light emitting element pitch Pel. Two light emitting elements 2951 (first light emitting element and second light emitting element) arranged at the light emitting element pitch Pel in the longitudinal direction LGD form a spot latent image adjacent to the main scanning direction MD. That is, the two light emitting elements 2951 that form the spot SP adjacent in the main scanning direction MD belong to different light emitting element rows 2951R and are arranged at different positions in the width direction LTD. Therefore, also in this modified example, the light emitting element 2951 can be enlarged, and the spot SP can be formed with a sufficient amount of light, so that the latent image can be formed satisfactorily.

  In this modification, the drive circuit DC is arranged on one side in the width direction LTD with respect to the light emitting element group 295. This drive circuit DC is provided for each light emitting element group 295, and can be constituted by a TFT (Thin Film Transistor) or the like. The drive circuit DC and each light emitting element 2951 of the light emitting element group 295 are electrically connected by a wiring WL (first wiring, second wiring). The arrangement of the wiring WL is as follows. Each wiring WL is connected to one side of the light emitting element 2951 in the width direction LTD. Then, each wiring WL is drawn out to one side in the width direction LTD. At this time, the wiring WL connected to the light emitting element rows 2951R_2 and 2951R_3 is drawn out between the light emitting elements 2951 of the light emitting element rows 2951R other than the connection destination. Each wiring WL is drawn to the outside of the lens LS in plan view. In this way, each wiring WL drawn out to one side in the width direction LTD with respect to the light emitting element group 295 is connected to the drive circuit DC. Then, the drive circuit DC gives a signal to each light emitting element 2951 through the wiring WL to drive each light emitting element 2951.

  Also in this modified example, each wiring WL connected to the light emitting element 2951 is drawn out to one side in the width direction LTD. Therefore, the wirings WL can be routed together. For this reason, the wiring WL can be easily routed, and this modification is preferable.

  In particular, in this modification, the drive circuit DC (circuit) electrically connected to the wiring WL is disposed on one side in the width direction LTD. Therefore, the wirings WL drawn from the light emitting elements 2951 to one side in the width direction LTD can be connected together to the drive circuit DC, and the wirings WL can be easily routed. Furthermore, by arranging such a drive circuit DC for each light emitting element group 295, the drive circuit DC can be provided near each light emitting element group 295, and the wiring WL can be made relatively short. As a result, a signal with less dullness due to the stray capacitance of the wiring WL can be supplied to the light-emitting element 2951. This structure is advantageous for a good latent image forming operation.

  Next, a modification shown in FIG. 21 will be described. Note that the main difference between the modification example of FIG. 21 and the modification example of FIG. 20 is an arrangement mode of the wiring WL connected to the light emitting element row 2951R_3. Therefore, in the following, this difference will be mainly described, and the common parts of the modified example of FIG. 21 and the modified example of FIG. As shown in FIG. 21, the wiring WL connected to the light emitting element row 2951R_3 bypasses the light emitting element rows 2951R_2 and 2951R_1 other than the connection destination and the wiring WL connected to them, and the width direction LTD of the light emitting element group 295 Is pulled out to one side. Accordingly, since the number of wirings WL that pass between the light emitting elements 2951 of the light emitting elements 2951R_1 and 2951R_2 can be suppressed, the modification has an advantageous configuration for increasing the size of the light emitting element 2951.

  Next, a modification of FIG. 22 will be described. The characteristic part of the modification shown in the figure is the contact CT provided in the light emitting element 2951, and the other parts are common to the embodiment shown in FIG. Therefore, hereinafter, the characteristic part of the modified example of FIG. 22 will be mainly described, and the parts common to the example of FIG.

  The contact CT connects an anode material such as ITO (Indium Tin Oxide) of the organic EL element and the wiring WL. In this modification, the contact CT is disposed in the vicinity of the light emitting element 2951 to increase the degree of freedom of the wiring WL. Furthermore, the modification has the following effects by devising the arrangement of the contacts CT. That is, when the contact CT is close to the light emitting element 2951, the contact CT may affect the application of the organic EL material in the manufacturing process of the light emitting element 2951. For this reason, uneven coating of the organic EL material is likely to occur. However, in this modification, the contact CT is disposed on one side of the width direction LTD with respect to each light emitting element 2951. Accordingly, it is relatively easy to control the application conditions of the organic EL material. As a result, uneven coating of the organic EL material can be suppressed and a favorable light emitting element 2951 can be formed.

  By the way, in the said embodiment, the shape of the light emitting element 2951 was circular. However, the shape of the light emitting element 2951 is not limited to this. FIG. 23 is a plan view showing a modification of the shape of the light emitting element. As shown in the figure, in this modification, the light emitting element 2951 has a rectangular shape. When a plurality of rectangular light emitting elements 2951 are arranged at a certain light emitting element pitch and a plurality of circular light emitting elements 2951 are arranged at a certain light emitting element pitch, the rectangular light emitting elements 2951 are more circular. Since the surface area can be made larger than that of the light emitting element 2951, it is advantageous for increasing the amount of light.

  Further, in the above embodiment, each wiring WL connected to the light emitting elements 2951 belonging to the same light emitting element group 295 is drawn out to one side of the light emitting element group in the width direction LTD. However, these wirings WL may be drawn out to the other side of the light emitting element group in the width direction LTD. In short, each wiring WL connected to the light emitting elements 2951 belonging to the same light emitting element group 295 may be led out to the same side of the light emitting element group 295 in the width direction LTD.

  Further, the lead-out side of the wiring WL may be different for each light emitting element group 295. That is, for example, each wiring WL connected to the light emitting element 2951 belonging to the light emitting element group 295_1 (FIG. 9) is drawn out to one side, whereas the light emitting element 2951 belonging to the light emitting element group 295_2 (FIG. 9). Each of the wirings WL connected to may be configured to be drawn to the other side. Of course, the lead-out side of the wiring WL may be matched among all the light emitting element groups 295.

  In the above embodiment, the light emitting element group column 295C is configured by the three light emitting element groups 295. However, the number of the light emitting element groups 295 constituting the light emitting element group column 295C is not limited thereto.

  In the above embodiment, an organic EL is used as the light emitting element 2951. However, a light emitting material that can be used as the light emitting element 2951 is not limited thereto, and, for example, an LED (Light Emitting Diode) is used as the light emitting element 2951. May be.

  20 to 23, each wiring WL is connected to the drive circuit DC. However, each wiring WL may be connected to an FPC (Flexible Printed Circuits) or the like, and a signal may be input to each light emitting element 2951 through the FPC.

  In the above embodiment, the main scanning resolution and the sub-scanning resolution are both 600 dpi, but each resolution is not limited to 600 dpi. In particular, with regard to the sub-scanning resolution, a resolution of 600 dpi or more can be realized relatively easily by subdividing the light emission time of the light emitting element 2951 by pulse width modulation control called PWM (Pulse Width Modulation) control. Therefore, for example, the sub-scanning resolution may be increased by setting the sub-scanning resolution to 2400 dpi while the main-scanning resolution is set to 600 dpi. At this time, since the sub-scanning resolution is four times the main scanning resolution, the sub-scanning pixel pitch Rsd is a quarter of the main scanning pixel pitch Rmd.

  In the above embodiment, the latent image is developed with so-called dry toner to form an image. However, the latent image may be developed with a liquid developer. FIG. 24 is a diagram showing an outline of an apparatus for developing with a liquid developer. Since the difference between the apparatus shown in FIG. 3 and the apparatus shown in FIG. 3 is mainly the structure of the developing unit, the following description will mainly describe the developing unit, and the other parts will be denoted by the same reference numerals and description thereof will be omitted. .

  Four developing units 90Y (for yellow), 90M (for magenta), 90C (for cyan), and 90K (for black) corresponding to each toner color are arranged side by side along the conveyance direction of the intermediate transfer belt 81. ing. In each developing unit 90K and the like, an oil container 901 that stores carrier oil, a toner container 902 that stores high-concentration toner, and a stirrer 903 are provided. In the agitator 903, the carrier oil supplied from the oil container 901 and the high-concentration toner supplied from the toner container 902 are agitated to generate a liquid developer whose density is adjusted. The liquid developer thus generated is supplied to the developer container 904. A supply roller 905 and an anilox roller 906 are provided inside the developer container 904. The lower part of the supply roller 905 is immersed in the liquid developer inside the developer container 904. The supply roller 905 rotates in the direction of the arrow in the drawing to draw up the liquid developer and convey it to the anilox roller 906. The anilox roller 906 rotates in the direction of the arrow in the figure, and applies the liquid developer conveyed from the supply roller 905 to the developing roller 907.

  The developing roller 907 is in contact with the photosensitive drum 21 at the developing position. The developing roller 907 is rotatable in the direction of the arrow in the figure, and the liquid developer supplied from the anilox roller 906 is carried on the surface of the developing roller 907 and supplied to the developing position. The toner contained in the liquid developer supplied in this manner adheres to the latent image on the surface of the photosensitive drum, and development is executed.

  A cleaner blade 908 is in contact with the developing roller 907 on the downstream side of the developing position in the rotation direction of the developing roller 907. The liquid developer is peeled off from the surface of the developing roller 907 by the cleaner blade 908 and recovered in the recovery container 909. Further, the liquid developer recovered in the recovery container 909 is returned to the agitator 903 and reused.

  In the rotational direction D21 of the photosensitive drum, two photosensitive squeeze rollers 910 are provided in contact with the surface of the photosensitive drum 21 on the downstream side of the developing position. The photoconductor squeeze roller 910 peels off the carrier oil from the surface of the photoconductor drum 21, thereby adjusting the amount of carrier oil contained in the liquid developer on the surface of the photoconductor drum 21. Further, the peeled carrier oil is once collected in the collection container 911 and then returned to the agitator 903 for reuse.

  An image obtained by developing the latent image at the development position is transferred to the intermediate transfer belt 81 at the primary transfer position TR1. In the transport direction D81 of the intermediate transfer belt 81, a belt squeeze roller 912 is in contact with the downstream side of the primary transfer position TR1. The belt squeeze roller 912 peels off the carrier oil from the surface of the intermediate transfer belt 81, so that the amount of carrier oil contained in the liquid developer on the surface of the intermediate transfer belt 81 is adjusted. Further, the stripped carrier oil is collected in a collection container 913.

  The image primarily transferred in this way is secondarily transferred to the paper. This secondary transfer operation is executed by two secondary transfer rollers 82 and a backup roller 121 disposed opposite to each secondary transfer roller 82. Each backup roller 121 is provided with a cleaner blade 1211 in contact therewith, and the liquid developer remaining on the backup roller 121 is peeled off by the cleaner blade 1211 and collected in a collection container 1212.

  Thus, in the apparatus of FIG. 24, the latent image is developed (liquid development) by the liquid developer. By the way, in general, such liquid development can perform latent image development with relatively high accuracy. Therefore, it is preferable that the development of the spot latent image formed favorably by the above invention is performed by liquid development.

Explanatory drawing of the term used by this specification. Explanatory drawing of the term used by this specification. 1 is a diagram illustrating an example of an image forming apparatus according to the present invention. FIG. 4 is a diagram illustrating an electrical configuration of the image forming apparatus in FIG. 3. The perspective view which shows the outline of the line head concerning this invention. FIG. 6 is a cross-sectional view in the width direction of the line head shown in FIG. 5. The perspective view which shows the outline of a lens array. Sectional drawing of the longitudinal direction LGD of a lens array. The figure which shows the structure of the back surface of a head board | substrate. The top view which shows the structure of a light emitting element group. The block diagram which shows the structure of a main controller. The block diagram which shows the structure of a head controller. FIG. 3 is a block diagram showing a configuration of a head control block in the present embodiment. The perspective view for demonstrating spot formation operation | movement. FIG. 4 is a diagram showing spot groups formed on the surface of a photosensitive drum in the present embodiment. Explanatory drawing of the subscanning position in a group. The figure which shows an example of a spot latent image formation operation | movement. The top view which shows another structure of a light emitting element group. The top view which shows another structure of a light emitting element group. The top view which shows the modification of a light emitting element group and wiring. The top view which shows the modification of a light emitting element group and wiring. The top view which shows the modification of a light emitting element group and wiring. The top view which shows the modification of a light emitting element group and wiring. FIG. 2 is a diagram illustrating an outline of an apparatus that performs development with a liquid developer.

Explanation of symbols

  21Y, 21K ... photosensitive drum (latent image carrier), 29 ... line head, 293 ... head substrate (substrate), 295 ... light emitting element group, 295C ... light emitting element group column, 2951 ... light emitting element, 2951R ... light emitting element row 299 ... Lens array, LS ... Lens, SP ... Spot, SG ... Spot group, MD ... Main scanning direction (first direction), SD ... Sub scanning direction (second direction), LGD ... Longitudinal direction, LTD ... Width direction , WL ... wiring, Pel ... light emitting element pitch

Claims (14)

An imaging optical system disposed in the first direction;
A first light emission arranged in a second direction orthogonal or substantially orthogonal to the first direction while emitting light imaged by the imaging optical system to form a condensing portion adjacent to the first direction. An element and a second light emitting element;
A first wiring electrically connected to the first light emitting element and drawn from the light emitting element on one side in the second direction;
An exposure head, wherein the exposure head is electrically connected to the second light emitting element and has a second wiring led out from the light emitting element on one side in the second direction.   The exposure head according to claim 1, further comprising a circuit that is disposed on one side in the second direction and is electrically connected to the first wiring and the second wiring.   3. The exposure head according to claim 2, wherein the circuit is a drive circuit that drives the first light emitting element and the second light emitting element.   4. The exposure head according to claim 3, wherein the driving circuit is a TFT.   The exposure head according to claim 2, wherein the circuit is an FPC. A latent image carrier;
An imaging optical system arranged in a first direction, and a light imaged on the latent image carrier by the imaging optical system is emitted to form a latent image adjacent to the first direction on the latent image carrier. And a first light emitting element and a second light emitting element arranged in a second direction orthogonal or substantially orthogonal to the first direction, and electrically connected to the first light emitting element and on one side of the second direction. A first wiring drawn from the light emitting element; and an exposure head electrically connected to the second light emitting element and having a second wiring drawn from the light emitting element on one side in the second direction;
An image forming apparatus comprising: a developing unit that develops the latent image formed on the latent image carrier by the exposure head.   The image forming apparatus according to claim 6, further comprising a circuit disposed on one side in the second direction and electrically connected to the first wiring and the second wiring.   8. The image formation according to claim 6, wherein the first light emitting element and the second light emitting element emit light according to the movement of the latent image carrier to form the latent image adjacent in the first direction. apparatus.   9. The first light emitting element row in which light emitting elements are arranged in a first direction of the first light emitting element and the second light emitting element row in which light emitting elements are arranged in a first direction of the second light emitting elements are arranged. The image forming apparatus described in 1.   The image forming apparatus according to claim 9, wherein a width of the first light emitting element in the first direction is longer than an interval between the first light emitting element and the second light emitting element in the first direction. The second of the first latent image formed by the first light emitting element and the second latent image formed by the second light emitting element when the first light emitting element and the second light emitting element emit light simultaneously. The direction spacing is
The image forming apparatus according to claim 9, wherein the image forming apparatus is an integral multiple of an interval between pixels in the second direction.   The image forming apparatus according to claim 6, wherein the light emitting element is an organic EL element.   The image forming apparatus according to claim 12, wherein the organic EL element is a bottom emission type.   The image forming apparatus according to claim 6, wherein the latent image is developed with a liquid developer.

Images