JP2011051311A - Exposure head and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique which attains good exposure by highly accurately forming a supporting member for supporting a lens array and thereby controlling a gap of the positional relationship between a light emitting element and a lens. <P>SOLUTION: The exposure head has a light emitting element array which has the light emitting elements arranged in a first direction to emit light and a light emitting element substrate 293 where the light emitting elements are arranged, first supporting members SP1 which are arranged contacting to the light emitting element substrate 293 and are constituted of the same material as that of the light emitting element substrate 293, second supporting members SP1 which are arranged contacting to the light emitting element substrate 293 in a second direction orthogonal or nearly orthogonal to the first direction of the first supporting members SP1 and are constituted of the same material as that of the light emitting element substrate 293, and the lens array LA1 which is supported by the first supporting members SP1 and second supporting members SP1 and has the lenses LS1 for imaging the light emitted from the light emitting elements. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an exposure head that forms an image of light from a light emitting element on an exposed surface using a lens, and an image forming apparatus including the exposure head.

  Conventionally, as described in Patent Document 1, an exposure head including a light emitting element and a lens (line head of the same document) is known. That is, in the exposure head of the same document, a light emitting element substrate having a light emitting element and a lens array having a lens are provided so as to face each other, and light emitted from the light emitting element passes through the lens and is exposed. A surface is irradiated to form a spot.

  In this exposure head, a light shielding member is provided between the light emitting element substrate and the lens array. The light shielding member has a light guide hole penetrating from the light emitting element toward the lens, and light from the light emitting element enters the lens after passing through the light guide hole. Further, the light shielding member is disposed in contact with each of the light emitting element substrate and the lens array, and functions as a support member that supports the lens array with respect to the light emitting element substrate while maintaining a distance from the light emitting element substrate. Plays.

JP 2008-254418 A

  However, in the above-described conventional exposure head, when the light emitting element substrate and the light shielding member serving as a support member are made of different materials, the following problems may occur. That is, the light emitting element substrate is made of a material that can be formed with high accuracy in order to ensure the positional accuracy of the light emitting element. On the other hand, when the light shielding member as the support member is made of a material different from that of the light emitting element substrate, there is a possibility that the shape cannot be formed with high accuracy. By the way, if the shape of the support member that supports the lens array varies, the positional relationship between the light emitting element substrate and the lens array varies. As described above, the positional relationship between the light emitting element substrate and the lens array varies, thereby causing a deviation in the positional relationship between the light emitting element disposed on the light emitting element substrate and the lens of the lens array. There is a possibility that a spot cannot be formed by a device at a desired position and good exposure cannot be realized.

  The present invention has been made in view of the above problems, and an exposure head that forms an image of light from a light emitting element on an exposed surface by a lens and a support for supporting a lens array in an image forming apparatus including the exposure head It is an object of the present invention to provide a technique that can realize good exposure by suppressing deviation of the positional relationship between a light emitting element and a lens by making it possible to form a member with high accuracy.

  In order to achieve the above object, an exposure head according to the present invention includes a light emitting element that is arranged in a first direction and emits light, and a light emitting element array having a light emitting element substrate on which the light emitting element is arranged, A first support member disposed in contact with the light emitting element substrate and made of the same material as the light emitting element substrate, and a second orthogonal to or substantially orthogonal to the first direction of the first support member The light emitting device substrate is disposed in contact with the light emitting device substrate in the direction, and is supported by the second support member made of the same material as the light emitting device substrate, the first support member, and the second support member, and emits light. And a lens array having a lens that forms an image of light emitted from the element.

  In order to achieve the above object, an image forming apparatus according to the present invention includes a latent image carrier on which a latent image is formed, a light emitting element that is disposed in a first direction and emits light, and a light emitting element. A light emitting element array having a light emitting element substrate, a first support member disposed in contact with the light emitting element substrate and made of the same material as the light emitting element substrate, and a first direction of the first support member; A second support member disposed in contact with the light emitting element substrate in a second direction orthogonal or substantially orthogonal and made of the same material as the light emitting element substrate; and the first support member and the second support member And an exposure head for exposing the latent image carrier to form a latent image, and a latent image formed by the exposure head. In the development section to develop and in the development section Is characterized by having a transfer unit for transferring the transfer material image is image.

  In the invention thus configured (exposure head, image forming apparatus), the first support member and the second support member are made of the same material as the light emitting element substrate. Therefore, similarly to the light-emitting element substrate, the shapes of the first support member and the second support member can be formed with high accuracy. Therefore, variation in the positional relationship between the light emitting element substrate and the lens array supported by the first support member and the second support member is suppressed, and as a result, the positional relationship between the light emitting element and the lens is stabilized. As a result, a good exposure operation can be realized.

  The light emitting element substrate may be a light transmissive member, and light emitted from the light emitting element may pass through the light emitting element substrate and be imaged by a lens. According to this configuration, the light emitted from the light emitting element passes through the light emitting element substrate, which is a light transmissive member, and is imaged by the lens. It will be arranged on the surface.

  A third support member disposed in contact with the lens array in a third direction orthogonal to the first direction and the second direction of the first support member; And a fourth support member disposed in contact with the lens array in a direction 3, and a third support member and a second lens array supported by the fourth support member. According to this configuration, the third support member is disposed in contact with the lens array in the third direction of the first support member, and the fourth support member is disposed in the third direction of the second support member. The second lens array is disposed in contact with the lens array, and is supported by the third and fourth support members.

  The third support member and the fourth support member may be made of the same material as the light emitting element substrate. According to this configuration, since the third supporting member and the fourth supporting member are made of the same material as the light emitting element substrate, the shapes of the third supporting member and the fourth supporting member are increased as in the light emitting element substrate. It can be formed with high accuracy. Therefore, it is possible to suppress variation in the positional relationship between the light emitting element substrate and the second lens array supported by the third support member and the fourth support member.

  Further, the distance in the second direction between the first support member and the second support member may be wider than the distance in the second direction between the third support member and the fourth support member. . According to this configuration, the interval in the second direction between the first support member and the second support member is wider than the interval in the second direction between the third support member and the fourth support member. Therefore, it is possible to secure a space for disposing another member such as a light shielding member between the first support member and the second support member.

  Further, the first support member and the second support member may be disposed at a position different from a position through which light emitted from the light emitting element and imaged by the lens passes. According to this configuration, the first and second support members are disposed at a position different from the position through which the light emitted from the light emitting element and imaged by the lens passes. The second support member does not adversely affect the light incident on the lens from the light emitting element.

1 is a diagram illustrating an example of an image forming apparatus to which the present invention can be applied. FIG. 2 is a block diagram showing an electrical configuration provided in the image forming apparatus of FIG. 1. The perspective view which shows the outline of one Embodiment of a line head. The partial top view which planarly viewed the head substrate from the thickness direction. The fragmentary sectional view of the line head in the AA line of FIG. The partial top view which shows the positional relationship of each member, such as a head board | substrate. The figure which shows the course of the light which permeate | transmits a spacer.

A. Embodiment FIG. 1 is a diagram illustrating an example of an image forming apparatus to which the present invention is applicable. FIG. 2 is a block diagram showing an electrical configuration of the image forming apparatus shown in 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. 1 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. At this time, every time the main controller MC receives the horizontal request signal HREQ from the head controller HC, the main controller MC supplies video data VD for one line to the head controller HC in the main scanning direction MD. 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 ENG 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 feeding unit 11 are also disposed in the housing body 3. In FIG. 1, 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 21 is arranged so that the axial direction is parallel or 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. 1, 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 be driven to rotate in contact with the surface of the photosensitive drum 21 at a charging position, and is rotated 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 a 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 spaced apart from the photosensitive drum 21, the longitudinal direction of the line head 29 is parallel or substantially parallel to the main scanning direction MD, and the width direction of the line head 29 is the sub-scanning direction SD. Parallel or substantially parallel to The line head 29 includes a plurality of light emitting elements, and each light emitting element emits light according to video data VD from the head controller HC. The surface of the photosensitive drum 21 is irradiated with light from the light emitting element, whereby an electrostatic latent image is formed on the surface of the photosensitive drum 21.

  The developing unit 25 has a developing roller 251 that carries toner on the surface thereof. 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. Moves from the developing roller 251 to the photosensitive drum 21, and the electrostatic latent image formed by the line head 29 is made visible.

  The toner image that has been made visible at the developing position as described above is conveyed in the rotational direction D21 of the photosensitive drum 21, and then transferred to the transfer belt 81 at the primary transfer position TR1 where the photosensitive belt 21 abuts. Primary transfer.

  In this embodiment, a photoreceptor cleaner 27 is provided in contact with the surface of the photoreceptor drum 21 on the downstream side of the primary transfer position TR1 in the rotation direction D21 of the photoreceptor 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. 1, and the direction of an arrow D81 (conveying direction) stretched around these rollers. 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 the respective 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). When the color mode is executed, all the primary transfer rollers 85Y, 85M, 85C, and 85K are positioned on the image forming stations Y, M, C, and K as shown in FIG. A primary transfer position TR 1 is formed between each photosensitive drum 21 and the transfer belt 81 by being pushed and brought into contact with the photosensitive drum 21 included in each of the forming stations Y, M, C, and K. Then, by applying a primary transfer bias from the primary transfer bias generating unit to the primary transfer roller 85 at an appropriate timing, the toner images formed on the surface of each photosensitive drum 21 correspond to each. 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, which face 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 being in contact with 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 drive 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 drive 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 manner, 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 paper feed unit 11 includes a paper feed unit having a paper feed cassette 77 capable of stacking and holding sheets and a pickup roller 79 for feeding sheets one by one from the paper feed 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 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 out of the surface 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 portion of the housing body 3.

  Further, in this apparatus, a cleaner unit 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 contacting the tip of the cleaner blade 711 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.

  FIG. 3 is a perspective view schematically showing an embodiment of the line head. In the drawing, in order to facilitate understanding of the configuration of the line head 29 in the thickness direction TKD, the end of the line head 29 in the longitudinal direction LGD (lower left end in FIG. 3) is shown in cross section. Here, the thickness direction TKD is a direction perpendicular or substantially perpendicular to the longitudinal direction LGD and the width direction LTD, and a light emitting element E to be described later emits light (that is, a side from the line head 29 toward the photosensitive drum 21). ). In the line head 29, the head substrate 293, the light shielding member 297, the first lens array LA1, the second lens array LA2, and the lens cover CV (see FIG. 5) are arranged in this order in the thickness direction TKD. From the back surface (strictly speaking, from the back surface of the sealing member 294 provided on the head substrate 293), a rigid member 299 has a schematic configuration that supports these members. Then, the light from the light emitting element E of the head substrate 293 passes through the light guide hole 2971 of the light shielding member 297 and is imaged by the lenses LS1 and LS2 of the first and second lens arrays LA1 and LA2. Next, the detailed configuration of each member will be described with reference to FIGS. 3, 4, and 5. In the description of the embodiment, the downstream side in the thickness direction TKD (upper side in FIG. 3) is referred to as “one side in the thickness direction TKD”, and the upstream side in the thickness direction TKD (lower side in FIG. 3). Is referred to as “the other side (in the thickness direction TKD)”. In addition, one surface of the substrate or the flat plate is referred to as a front surface, and the other surface of the substrate or the flat plate is referred to as a back surface. In FIG. 3, for the sake of convenience, a glass lens cover CV that covers the second lens array LA2, an FPC (Flexible Printed Circuit) 296 attached to the head substrate 293, a cover member 298 that protects the head substrate 293, etc. The illustration of FIG. 5 is omitted.

  FIG. 4 is a partial plan view of the head substrate 293 viewed from the thickness direction TKD, and corresponds to a case where the back surface 293-t of the head substrate 293 is seen through from one side of the thickness direction TKD (upper side in FIG. 3). To do. FIG. 5 is a partial cross-sectional view of the line head in this embodiment, taken along line AA in FIG. 4, and corresponds to a case where the cross section is viewed from the longitudinal direction LGD (main scanning direction MD). This AA line cross section has a center of gravity (or three lenses LS1, etc.) of three light emitting element groups EG arranged in a line with a distance Dg in the longitudinal direction LGD and a distance Dt in the width direction LTD. Pass through the center of each lens). Moreover, the direction Dlsc shown in FIGS. 4 and 5 is a direction parallel to the line AA. Further, FIG. 4 shows the positional relationship between the light emitting element group EG formed on the head substrate 293, the first lens LS1 formed on the first lens array LA1, and the second lens LS2 formed on the second lens array LA2. For this reason, the first lens LS1 and the second lens LS2 are shown together with alternate long and short dash lines. Incidentally, the description of the first lens LS1 and the second lens LS2 in the drawing is for showing the positional relationship between them, and the first lens LS1 and the second lens LS2 are the back surface 293-t of the head substrate (FIG. 5). It does not indicate that it is formed. In FIG. 5, a member that is light transmissive (that is, transparent) is hatched with a set of points.

  The head substrate 293 is formed of a glass substrate (light transmissive substrate) that transmits light, and a plurality of light emitting elements E that are bottom emission type organic EL (Electro-Luminescence) elements are formed on the back surface 293-t of the head substrate. At the same time, it is sealed by a sealing member 294 (FIGS. 3 and 5). The plurality of light emitting elements E have the same emission spectrum, and emit a light beam toward the surface of the photosensitive drum 21. As shown in FIG. 4, the arrangement of the plurality of light emitting elements E formed on the head substrate back surface 293-t has a group structure. That is, 15 light emitting elements E are arranged in two rows and staggered in the longitudinal direction LGD to form one light emitting element group EG, and a plurality of light emitting element groups EG are dispersed in three rows and staggered in the longitudinal direction LGD. Are arranged.

  In more detail, this arrangement | positioning aspect can be demonstrated as follows. That is, in each light emitting element group EG, 15 light emitting elements E are arranged at different positions in the longitudinal direction LGD, and the longitudinal direction LGD of two light emitting elements E and E whose positions in the longitudinal direction LGD are adjacent to each other. Is the inter-element distance Pel (in other words, in each light emitting element group EG, 15 light emitting elements E are arranged in the longitudinal direction LGD with a pitch Pel). A plurality of light emitting element groups EG are discretely arranged along the longitudinal direction LGD with a group distance Peg longer than the element distance Pel to form one light emitting element group row GRa and the like. Further, three light emitting element group rows GRa, GRb, GRc are discretely arranged at different positions in the width direction LTD with a distance Dt therebetween, and each of the light emitting element group rows GRa, GRb, GRc is: They are mutually shifted by a distance Dg in the longitudinal direction LGD. Thus, the three light emitting element groups EG are arranged in a line in the direction Dlsc with a distance Dg in the longitudinal direction LGD and a distance Dt in the width direction LTD.

  Here, the inter-element distance Pel can be obtained as a distance in the longitudinal direction LGD between the geometric centroids of the two light emitting elements E to be processed. Further, the inter-group distance Peg is the geometric center of gravity of the light emitting element E at the other end of the light emitting element group EG on one side in the longitudinal direction LGD, and the longitudinal direction LGD of the two target light emitting element groups EG. The distance in the longitudinal direction LGD with the geometric center of gravity of the light emitting element E at the one end of the other light emitting element group EG can be obtained. The distance Dg can be obtained as a distance in the longitudinal direction LGD between the geometric centroids of two light emitting element groups EG whose positions in the longitudinal direction LGD are adjacent to each other. The distance Dt can be obtained as a distance in the width direction LTD between the geometric centroids of two light emitting element groups EG whose positions in the width direction LTD are adjacent.

  In addition, by applying the technology described in Japanese Patent Application Laid-Open No. 2004-082330, this embodiment includes a configuration for detecting the light amount of each light emitting element E in advance in order to help control the light amount of each light emitting element E. Yes. Specifically, on each of both sides of the head substrate back surface 293-t in the width direction LTD, a plurality of optical sensors SC are arranged in a line in the longitudinal direction LGD at a predetermined interval. Thus, the rows of the optical sensors SC are arranged on both sides in the width direction LTD with the plurality of light emitting element groups EG interposed therebetween. Each optical sensor SC outputs the result of detecting the light amount from the light emitting element E to the head controller HC, and the head controller HC controls the light amount of the light emitting element E thereafter based on the received light amount signal.

  Thus, the light emitting element group EG and the optical sensor SC are arranged on the back surface 293-t of the head substrate 293. On the other hand, a light shielding member 297 is disposed on the surface 293-h of the head substrate 293. The light shielding member 297 is formed with a light guide hole 2971 that penetrates in the thickness direction TKD. The light guide hole 2971 has a circular shape in plan view from the thickness direction TKD, and the inner wall has a black color. It is plated. One light guide hole 2971 is formed for each light emitting element group EG. That is, one light guide hole 2971 is opened for one light emitting element group EG. Thus, the light shielding member 297 is fixed in contact with the head substrate surface 293-h in a state where the light guide hole 2971 is opened in the light emitting element group EG.

  The purpose of providing such a light shielding member 297 is to prevent so-called stray light from entering the lenses LS1 and LS2. That is, each light emitting element group EG is provided with a dedicated imaging optical system composed of a pair of lenses LS1 and LS2. In such a configuration, it is desirable that the light beam be incident only on the lenses LS1 and LS2 provided in the light emitting element group EG which is its own emission source. However, some of the light beams may become stray light without being directed to the lenses LS1 and LS2 provided in the light emitting element group EG that is the emission source. If such stray light enters the lenses LS1 and LS2 provided in the light emitting element group EG that is not its own emission source, a so-called ghost may occur. On the other hand, in this embodiment, a light shielding member 297 is provided between the light emitting element group EG and the lenses LS1 and LS2. The light shielding member 297 is provided with a light guide hole 2971 whose inner wall is black-plated so as to open to the light emitting element group EG. Therefore, most of the stray light is absorbed by the inner wall of the light guide hole 2971. As a result, the above-described ghost can be suppressed and a good exposure operation can be realized.

  In addition, on one side of the light shielding member 297 in the thickness direction TKD, the first lens array LA1 is supported at a distance from the light shielding member 297. The first lens array LA1 is supported by a first spacer SP1 made of glass disposed in contact with the surface 293-h of the head substrate 293. Furthermore, on one side of the thickness direction TKD of the first lens array LA1, the second lens array LA2 is supported at a distance from the first lens array LA1. The second lens array LA1 is supported by a glass second spacer SP2 disposed in contact with the surface SB1-h of the glass substrate SB1 of the first lens array LA1. A support mode of the first lens array LA1 and the second lens array LA2 will be described with reference to FIGS. 3 to 5 and FIG.

  FIG. 6 is a partial plan view showing the positional relationship among the head substrate, the first spacer, the first lens array, the second spacer, and the second lens array of this embodiment, as viewed from one side in the thickness direction TKD. It corresponds to. In FIG. 6, for convenience, the first spacer SP1 and the second spacer SP2 are shown shifted in the longitudinal direction LGD. As shown in FIGS. 3 and 6, on the head substrate surface 293-h, a plurality of first spacers SP1 are arranged in a line with a gap CL1 in the longitudinal direction LGD. Note that the lengths of the gaps CL1 in the longitudinal direction LGD are equal to each other. Further, the rows of the first spacers SP1 are provided on both sides on one side and the other side in the width direction LTD. Thus, in a plan view from the thickness direction TKD, two rows of the first spacers SP1 are arranged across the region where the plurality of light emitting element groups EG are arranged. In other words, the light emitting element group EG (or the first lens LS1 and the second lens LS2) is arranged in two rows at positions off the one side and the other side in the width direction LTD. The head substrate 293 and the first spacer SP1 are fixed by a method using, for example, an ultraviolet curable adhesive.

  In this way, the first lens array LA1 is installed in the width direction LTD on the first spacers SP1 arranged in two rows, so that the first lens array LA1 is positioned with respect to the head substrate 293. To do. That is, the first spacer SP1 made of glass has a rectangular cross section, and one plane is in contact with the head substrate 293, and the other plane is in contact with the glass substrate SB1 of the first lens array LA1. The first lens array LA1 includes a plurality of first curable resin formed on a back surface SB1-t of a rhombus-shaped glass substrate SB1 whose both ends in the longitudinal direction LGD are cut obliquely (parallel to the direction Dlsc). One lens LS1 is arranged in an array. The plurality of first lenses LS1 are arranged in a three-row zigzag pattern corresponding to the arrangement of the opposing light emitting element groups EG (FIG. 4). The inner end surfaces SP1a and SP1b of the first spacer SP1 are shielded from light by a method such as applying a black paint or applying a light shielding tape.

  In this embodiment, a plurality of first lens arrays LA1 are arranged in a line in the longitudinal direction LGD. These first lens arrays LA1 are supported by first spacers SP1 arranged in a line with a gap CL1 in the longitudinal direction LGD. At this time, one first spacer SP1 supports two adjacent first lens arrays LA1 across the boundary BD1 across the longitudinal direction LGD. Thus, one long lens array is constituted by the plurality of first lens arrays LA1 arranged in the longitudinal direction LGD. The first spacer SP1 and the first lens array LA1 are fixed by a method using, for example, an ultraviolet curable adhesive.

  As shown in FIGS. 3 and 6, on the surface SB1-h of the glass substrate SB1 of the first lens array LA1, a plurality of second spacers SP2 are arranged in a line with a gap CL2 in the longitudinal direction LGD. Note that the lengths of the gaps CL2 in the longitudinal direction LGD are equal to each other. The rows of the second spacers SP2 are provided on both sides on one side and the other side in the width direction LTD. Thus, in a plan view from the thickness direction TKD, two rows of the second spacers SP1 are arranged across the region where the plurality of light emitting element groups EG are arranged. In other words, the light emitting element group EG (or the first lens LS1 and the second lens LS2) is arranged in two rows at positions off the one side and the other side in the width direction LTD. The first lens array LA1 and the second spacer SP2 are fixed by a method using, for example, an ultraviolet curable adhesive.

  In this way, the second lens array LA2 is installed in the width direction LTD on the second spacer SP2 arranged in two rows, so that the second lens array LA2 is positioned with respect to the first lens array LA1. Oppose in the state. That is, the second glass spacer SP2 has a rectangular cross section, one plane abuts against the glass substrate SB1 of the first lens array LA1, and the other plane contacts the glass substrate SB2 of the second lens array LA2. It touches. This second lens array LA2 has a plurality of second lens arrays LA2 formed on a back surface SB2-t of a rhombus-shaped glass substrate SB2 whose both ends in the longitudinal direction LGD are cut obliquely (parallel to the direction Dlsc). It has a configuration in which two lenses LS2 are arranged in an array. The plurality of second lenses LS2 are arranged in a three-row zigzag pattern corresponding to the arrangement of the first lenses LS1 facing each other (FIG. 4). The inner end faces SP2a and SP2b of the second spacer SP2 are shielded from light by a method such as applying a black paint or applying a light shielding tape.

  In this embodiment, a plurality of second lens arrays LA2 are arranged in a line in the longitudinal direction LGD, and the second spacers SP2 are arranged in a line with a gap CL2 in the longitudinal direction LGD. I support it. At this time, one second spacer SP2 supports two adjacent second lens arrays LA2 across the boundary BD2 across the longitudinal direction LGD. Thus, one long lens array is constituted by the second lens array LA2 arranged in the longitudinal direction LGD. The second spacer SP2 and the second lens array LA1 are fixed by a method using, for example, an ultraviolet curable adhesive. In addition, a flat glass lens cover CV is fixed to the surface SB2-h of the glass substrate SB2 of the second lens array LA2 by a method such as an ultraviolet curable adhesive.

  Thus, the lens LS1 of the first lens array LA1 and the lens LS2 of the second lens array LA2 are arranged in the thickness direction TKD, that is, arranged so that the optical axes OA of the lenses LS1 and LS2 coincide with each other. One imaging optical system is configured. This imaging optical system forms an inverted reduced image, and its magnification is negative and has an absolute value of less than 1. Then, as described in Japanese Patent Application Laid-Open No. 2008-036937, FIG. 11 and the like, the light emission of each light emitting element E is controlled according to the movement of the surface of the photosensitive drum 21 in the sub scanning direction SD. A line latent image extending in the MD can be formed.

  Here, the positional relationship between the first spacer SP1 and the second spacer SP2 will be described with reference to FIGS. In FIG. 5, the left end surface SP2a of the right second spacer SP2 is positioned on the left side (that is, the lens LS1, LS2 side, or the light emitting element group EG side) from the left end surface SP1a of the first spacer SP1. A first spacer SP1 and a second spacer SP2 are provided. That is, in FIG. 6, the upper end surface SP2a of the lower second spacer SP2 is located above the upper end surface SP1a of the first spacer SP1 (that is, the lens LS1, LS2 side, or the light emitting element group EG side). Thus, the first spacer SP1 and the second spacer SP2 are arranged. In FIG. 5, the right end surface SP2b of the left second spacer SP2 is positioned on the right side (that is, the lens LS1, LS2 side, or the light emitting element group EG side) with respect to the right end surface SP1b of the first spacer SP1. In addition, a first spacer SP1 and a second spacer SP2 are disposed. That is, in FIG. 6, the lower end surface SP2b of the upper second spacer SP2 is below the lower end surface SP1b of the first spacer SP1 (that is, the lens LS1, LS2 side, or the light emitting element group EG side). A first spacer SP1 and a second spacer SP2 are disposed so as to be positioned. That is, the interval in the width direction LTD of the first spacers SP1 disposed on both sides of the width direction LTD is such that both the second spacers SP2 disposed on both sides of the width direction LTD are included inside the width direction LTD. Thus, it is wider than the interval in the width direction LTD of the second spacer SP2. Advantages of disposing the first spacer SP1 and the second spacer SP2 in this way will be described with reference to FIG.

  FIG. 7 is a diagram illustrating a path of light passing through the spacer. FIG. 7A shows this embodiment, and is a partial sectional view in which a part of FIG. 5 is omitted. FIG. 7B is a diagram showing a reference example in which the arrangement of the first spacer and the second spacer is different from that of this embodiment. In this embodiment, since the first spacer SP1 and the second spacer SP2 are made of glass, light passes through the spacers SP1 and SP2. For this reason, if the arrangement of the first spacer SP1 and the second spacer SP2 is not fully considered, the transmitted light may become stray light.

  In this embodiment, for example, in FIG. 7A, the light GL1 that is transmitted through the first spacer SP1 on the right side and is not reflected by the end surface SP1a of the first spacer SP1 but is directed to the second spacer SP2 is reflected by the second spacer. The light is reflected by the end surface SP2a of SP2 and proceeds in a direction away from the lens LS2. Similarly, in FIG. 7A, the light GL2 that passes through the first spacer SP1 on the left side and is not reflected by the end surface SP1b of the first spacer SP1 but goes to the second spacer SP2 is the end surface of the second spacer SP2. Reflected by SP2b and proceeds away from the lens LS2. Therefore, generation of stray light can be suppressed.

  On the other hand, in the reference example of FIG. 7B, the first spacer and the second spacer are arranged at positions different from the embodiment. That is, in FIG. 7B, the left end surface SP12a of the right second spacer SP12 is positioned on the right side (that is, the side farther from the lenses LS1 and LS2) than the left end surface SP11a of the first spacer SP11. A first spacer SP11 and a second spacer SP12 are provided. Further, the right end surface SP12b of the left second spacer SP12 and the second spacer SP11 and the second spacer SP11 are positioned so as to be located on the left side (that is, the side farther from the lenses LS1 and LS2) than the right end surface SP11b of the first spacer SP11. A spacer SP12 is provided.

  Therefore, for example, in FIG. 7B, the light GL11 which passes through the first spacer SP11 on the right side and is not reflected by the end surface SP11a of the first spacer SP11 but goes to the left side from the end surface SP12a of the second spacer SP12 is There is a possibility of entering LS2. Similarly, in FIG. 7B, the light GL12 that passes through the first spacer SP11 on the left side and goes to the right side from the end surface SP12b of the second spacer SP12 may enter the lens LS2. Therefore, in the configuration as in the reference example of FIG. 7B, the possibility that stray light is generated is high.

  As described above, in the line head 29 according to this embodiment, the first spacer SP1 that supports the first lens array LA1 is disposed on both sides in the width direction LTD so as to contact the head substrate 293. The head substrate 293 is made of a glass substrate, and the first spacer SP1 is also made of the same material, that is, glass. Here, the glass can be easily formed with high accuracy. Therefore, similarly to the head substrate 293, the shape of the first spacer SP1 can be formed with high accuracy. As a result, variation in the positional relationship between the first lens array LA1 supported by the first spacer SP1 and the head substrate 293 can be suppressed, and the positional relationship between the light emitting element E and the lens LS1 can be stabilized. Thus, according to this embodiment, it is possible to realize a good exposure operation.

  In the line head 29 of this embodiment, the second spacer SP2 that supports the second lens array LA2 is disposed on both sides of the width direction LTD so as to contact the glass substrate SB1 of the first lens array LA1. . The second spacer SP2 is formed of the same material as the head substrate 293, that is, glass. Therefore, similarly to the head substrate 293, the shape of the second spacer SP2 can be formed with high accuracy. Thereby, variation in the positional relationship between the second lens array LA2 supported by the second spacer SP2 and the head substrate 293 can be suppressed, and the positional relationship between the light emitting element E, the lens LS1, and the lens LS2 can be stabilized.

  Further, in the line head 29 of this embodiment, the first and second spacers SP1 and SP2 on the right side in FIG. 7A, the end surface SP2a of the second spacer SP2 is lighter than the end surface SP1a of the first spacer SP1. It is arranged so as to be close to the EG (or the lenses LS1, LS2). Accordingly, in FIG. 7A, the transmitted light of the first spacer SP1 on the right side can be reflected by the end surface SP2a of the second spacer SP2, so that the right side of the first spacer SP1 on the right side in FIG. It is possible to suppress the transmitted light GL1 from becoming stray light. Further, in the line head 29 of this embodiment, in FIG. 7A, the first and second spacers SP1 and SP2 on the left side, the end surface SP2b of the second spacer SP2 is lighter than the end surface SP1b of the first spacer SP1. It is arranged so as to be close to the EG (or the lenses LS1, LS2). Therefore, in FIG. 7A, the transmitted light of the left first spacer SP1 can be reflected by the end face SP2b of the second spacer SP2, and thereby the left first spacer SP1 of FIG. It is possible to suppress the transmitted light GL2 from becoming stray light.

  In this embodiment, the first spacers SP1 are arranged on one side and the other side of the width direction LTD in a line in the longitudinal direction LGD with a gap CL1 therebetween. The first lens array LA1 is supported from both one side and the other side in the direction LTD. Therefore, it is possible to reliably support the first lens array LA1. In this embodiment, the second spacer SP2 is arranged on each of one side and the other side in the width direction LTD with a gap CL2 in a line in the longitudinal direction LGD. The second lens array LA2 is supported from both one side and the other side in the direction LTD. Therefore, it is possible to reliably support the second lens array LA2.

  In this embodiment, the first and second spacers SP1 and SP2 are arranged at positions deviated from the region where the light emitting element E (or the lenses LS1 and LS2) is provided to one side and the other side in the width direction LTD. It is installed. Therefore, interference between the light from each light emitting element E and the first and second spacers SP1 and SP2 is suppressed, and a sufficient amount of light is applied to the lens LS1 of the first lens array LA1 and the lens LS2 of the second lens array LA2. Can be made incident.

B. Others As described above, in the embodiment, the longitudinal direction LGD corresponds to the “first direction” of the present invention, the width direction LTD corresponds to the “second direction” of the present invention, and the thickness direction TKD The first lens array LA1 corresponds to the “lens array” of the present invention, the light emitting element substrate 293 and the light emitting element E correspond to the “light emitting element array” of the present invention. The photosensitive drum 21 corresponds to the “latent image carrier” of the invention, the line head 29 corresponds to the “exposure head” of the invention, and the head substrate 293 corresponds to the “light emitting element substrate” of the invention. The first spacer SP1 on one side in the width direction LTD (for example, the right side in FIG. 5) corresponds to the “first support member” of the present invention, and the first spacer SP1 on the other side (for example, the left side in FIG. 5). ) Corresponds to the “second support member” of the present invention, the second spacer SP2 on one side in the width direction LTD (right side in FIG. 5) corresponds to the “third support member” of the present invention, and the other The second spacer SP2 on the side (left side in FIG. 5) corresponds to the “fourth support member” of the present invention.

  The present invention is not limited to the above-described embodiment, and various modifications can be made to the above-described one without departing from the spirit of the present invention. For example, in the above embodiment, the imaging optical system is configured by the lens LS1 of the first lens array LA1 and the lens LS2 of the second lens array LA2, but the number of lenses constituting the imaging optical system is two. Not limited. For example, a third lens array may be provided and the imaging optical system may be configured with three lenses.

  For example, as shown in FIG. 6, in the above-described embodiment, one end of the lens array LA1 in the width direction LTD is supported by two spacers SP1 arranged in the longitudinal direction LGD. However, the number of spacers SP1 that support one end of the lens array LA1 in the width direction LTD is not limited to this.

  In the above embodiment, the gaps CL1 of the first spacers SP1 arranged in a line in the longitudinal direction LGD are equal to each other. However, the gaps CL1 may be different from each other.

  Also, the configuration of each first spacer SP1 can be changed as appropriate, and the configuration of all the first spacers SP1 may be the same, or the shape and size of SP1 for each first spacer. May be different. The same change can be made for the second spacer SP2.

  Further, the imaging optical system of the above embodiment forms an inverted reduced image, and its magnification is negative and has an absolute value of less than 1. However, the magnification of the imaging optical system is However, it may be positive and may have an absolute value of 1 or more.

  In the above embodiment, the lenses are arranged in a staggered manner in three rows in each of the lens arrays LA1 and LA2, but the lens arrangement is not limited to this.

  In the above embodiment, the lenses LS1 and LS2 are formed on the back surfaces of the lens arrays LA1 and LA2. However, for example, the lenses LS1 and LS2 may be formed on the surfaces of the lens arrays LA1 and LA2.

  Various changes can be made to the shape and size of the lens arrays LA1 and LA2.

  Moreover, in the said 1st Embodiment, although the several light emitting element group EG was arrange | positioned by 3 rows zigzag, the arrangement | positioning aspect of the some light emitting element group EG is not restricted to this.

  In the above embodiment, the light emitting element group EG is composed of 15 light emitting elements E. However, the number of light emitting elements E constituting the light emitting element group EG is not limited to this.

  Moreover, in the said embodiment, in the light emitting element group EG, although the some light emitting element E was arrange | positioned by 2 rows zigzag, the arrangement | positioning aspect of the some light emitting element E in the light emitting element group EG is restricted to this. Absent.

  In the above embodiment, a bottom emission type organic EL element is used as the light emitting element E. However, a top emission type organic EL element may be used as the light emitting element E, or an LED (Light Emitting Diode) other than the organic EL element may be used as the light emitting element E.

  Further, the arrangement of the optical sensor SC can be variously changed in addition to the above. For example, since the first spacer SP1 is made of glass and transmits light, it may be disposed on the side surface of the first spacer SP1. Moreover, you may comprise so that the optical sensor SC may not be provided.

  LGD: longitudinal direction, LTD: width direction, TKD: thickness direction, 21: photosensitive drum, 29 ... line head, 293 ... head substrate, 293-h ... head substrate surface, 293-t ... head substrate back surface, E ... Light emitting element, EG ... Light emitting element group, LA1 ... Lens array, LA2 ... Lens array, OA ... Optical axis, SB1 ... Glass substrate, SB2 ... Glass substrate, LS1 ... Lens, LS2 ... Lens, SP1 ... Spacer, SP2 ... Spacer, SP1a, SP2a, SP1b, SP2b ... (spacer) end face

Claims (7)

A light emitting element array having a light emitting element disposed in a first direction and emitting light, and a light emitting element substrate on which the light emitting element is disposed;
A first support member disposed in contact with the light emitting element substrate and made of the same material as the light emitting element substrate;
The first support member is disposed in contact with the light emitting element substrate in a second direction orthogonal or substantially orthogonal to the first direction, and is made of the same material as the light emitting element substrate. Two support members;
A lens array supported by the first support member and the second support member, and having a lens for imaging light emitted from the light emitting element;
An exposure head comprising: The light emitting element substrate is a light transmissive member,
The exposure head according to claim 1, wherein the light emitted from the light emitting element passes through the light emitting element substrate and forms an image with the lens. A third support member disposed in contact with the lens array in a third direction orthogonal to the first direction and the second direction of the first support member;
A fourth support member disposed in contact with the lens array in the third direction of the second support member;
A second lens array supported by the third support member and the fourth support member;
The exposure head according to claim 1, comprising:   The exposure head according to claim 3, wherein the third support member and the fourth support member are made of the same material as that of the light emitting element substrate.   The distance in the second direction between the first support member and the second support member is greater than the distance in the second direction between the third support member and the fourth support member. The exposure head according to claim 3 or 4, which is wide.   The first support member and the second support member are disposed at a position different from a position where light emitted from the light emitting element and imaged by the lens passes. The exposure head according to any one of the above. A latent image carrier on which a latent image is formed;
A light emitting element arranged in a first direction to emit light, a light emitting element array having a light emitting element substrate on which the light emitting element is arranged, a light emitting element substrate disposed in contact with the light emitting element substrate, and the light emitting element substrate The first support member is made of the same material as the first support member, and is disposed in contact with the light emitting element substrate in a second direction orthogonal or substantially orthogonal to the first direction of the first support member and A second support member made of the same material as the light-emitting element substrate; and a lens that images the light emitted from the light-emitting element while being supported by the first support member and the second support member. An exposure head comprising a lens array and exposing the latent image carrier to form the latent image;
A developing unit for developing the latent image formed by the exposure head;
A transfer unit that transfers the image developed by the developing unit to a transfer material;
An image forming apparatus comprising:

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