JP2011051310A - Optical unit, exposure head, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique whereby a lens array can surely be supported parallel in an optical unit which images incident light by a plurality of lenses, an exposure head, and an image forming apparatus equipped with the exposure head. <P>SOLUTION: The optical unit includes a first lens array LA1 with lenses LS1, a glass member SP2 which is arranged contacting to the first lens array LA1, and a second lens array LA2 arranged contacting to a surface opposed to the first lens array LA1 to the glass member SP2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical unit that forms an image of incident light with a plurality of lenses, an exposure head, and an image forming apparatus including the exposure head.

  Conventionally, as described in Patent Document 1, an exposure head (line head in the same document) having an optical unit that forms an image of incident light by a plurality of lenses has been proposed. That is, the exposure head includes a light emitting element substrate having a light emitting element (head substrate of the same document), a light shielding member having a light guide hole arranged corresponding to the light emitting element of the light emitting element substrate, and the light emitting element of the light emitting element substrate. A first lens array having a first lens formed corresponding to the first lens array, and a second lens array having a second lens formed corresponding to the light emitting element of the light emitting element substrate, The optical axis of the lens and the optical axis of the second lens are arranged so as to coincide with each other. And the light inject | emitted from the light emitting element of the light emitting element board | substrate passes through the light guide hole of the light shielding member, and injects into the 1st lens of a 1st lens array, This incident light is 1st lens and 2nd The lens is imaged on the exposed surface. That is, the exposure head has an optical unit that forms incident light with the first lens and the second lens. The exposure head also includes a case for holding the first and second lens arrays. That is, the first and second lens arrays are held by the inner wall surface of the case at a position facing the exposed surface at a distance from each other.

JP 2008-254418 A (FIG. 23)

  By the way, in the optical unit of the exposure head described in Patent Document 1, unless the first lens array and the second lens array are supported in parallel with each other, the optical axis of the first lens and the optical axis of the second lens are used. And may not match. If the optical axis of the first lens and the optical axis of the second lens do not coincide with each other, incident light cannot be suitably imaged on the surface to be exposed. Resulting in. Accordingly, in order to obtain an optical unit capable of suitably forming an image of light from the light emitting element on the exposed surface, it is necessary to support the first lens array and the second lens array in parallel with each other. However, as described in Patent Document 1, with the configuration in which the lens array is simply held by the inner wall surface of the case, it is difficult to reliably support the first and second lens arrays in parallel.

  The present invention has been made in view of the above problems, and in an optical unit and an exposure head that form an image of incident light by a plurality of lenses, and an image forming apparatus including the exposure head, the lens array is reliably supported in parallel. The purpose is to provide technology that makes it possible.

  In order to achieve the above object, an optical unit according to the present invention includes a first lens array having lenses, a glass member disposed in contact with the first lens array, and a first lens on the glass member. And a second lens array disposed in contact with the surface facing the array.

  In the invention configured as described above, the glass member is disposed in contact with the first lens array, and the second lens array is disposed in contact with the glass member on a surface facing the first lens array. ing. Here, the glass can easily form a highly accurate plane. Therefore, the first lens array and the second lens array are supported in parallel with high precision by bringing the surface of the glass member formed with high precision into contact with the first lens array and the second lens array, respectively. It becomes possible to do. As a result, the positional relationship between the lenses of the first lens array and the lenses of the second lens array can be stabilized.

  The first lens array has a substrate made of the same material as the glass member, the second lens array has a substrate made of the same material as the glass member, and the glass member is made of the first lens. It may be disposed in contact with the substrate of the array and in contact with the substrate of the second lens array on a surface facing the first lens array. According to this configuration, since the substrates of the first lens array and the second lens array are made of the same material as the glass member, the surfaces of the substrates can be easily formed with high accuracy. Therefore, since the glass member is disposed in contact with the substrate of each lens array, the first lens array and the second lens array can be more reliably supported in parallel with each other.

  In order to achieve the above object, an exposure head according to the present invention is a light emitting element array having a light emitting element arranged in a first direction to emit light and a light emitting element substrate on which the light emitting element is arranged. And a first glass member disposed in contact with the light emitting element substrate and a surface of the first glass member facing the light emitting element substrate and imaging light emitted from the light emitting element. A first lens array having a lens; a second glass member disposed in contact with the first lens array; and a second glass member supported by a surface facing the first lens array. And 2 lens arrays.

  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 disposed, a first glass member disposed in contact with the light emitting element substrate, a light emitting element supported by a surface of the first glass member facing the light emitting element substrate, and the light emitting element A first lens array having a lens for imaging light emitted from the first lens array, a second glass member disposed in contact with the first lens array, and a first lens array on the second glass member; An exposure head that includes a second lens array supported on opposite surfaces and exposes the latent image carrier to form a latent image; a developing unit that develops the latent image formed by the exposure head; and a developing unit. A transfer section for transferring the developed image to a transfer material; It is characterized by having a.

  In the invention thus configured (exposure head, image forming apparatus), the first glass member is disposed in contact with the light emitting element substrate, and the first glass member faces the light emitting element substrate with the first surface. The second glass member is supported by a surface of the second glass member facing the first lens array, and the second lens member is supported by the second glass member. Has been. Here, the glass can easily form a highly accurate plane. Therefore, the surface of the first glass member formed with high accuracy is brought into contact with the light emitting element substrate and the first lens array, and the surface of the second glass member formed with high accuracy is used as the first lens array. By making contact with the second lens array and the second lens array, the light emitting element substrate, the first lens array, and the second lens array can be supported in parallel with high accuracy. Thereby, the positional relationship among the light emitting elements of the light emitting element array, the lenses of the first lens array, and the lenses of the second lens array can be stabilized, and as a result, good exposure 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. Therefore, the light emitting element is the first lens array of the light emitting element substrate. It will be arrange | positioned on the surface on the opposite side.

  In addition, the first lens array is disposed in contact with the light emitting element substrate in a second direction orthogonal to or substantially orthogonal to the first glass member and the surface facing the light emitting element substrate. A third glass member disposed in contact with the first lens array, and a third glass member disposed in contact with the first lens array in a third direction orthogonal to the first direction and the second direction of the third glass member. And a fourth glass member disposed in contact with the second lens array on a surface facing the first lens array. According to this configuration, since the first and third glass members are disposed in contact with the light emitting element substrate and the first lens array, respectively, the light emitting element substrate and the first lens array are more reliably secured. In addition, they can be supported in parallel with high accuracy. In addition, since the second and fourth glass members are disposed in contact with the first lens array and the second lens array, respectively, the first lens array and the second lens array can be more reliably secured. In addition, they can be supported in parallel with high accuracy.

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

  Further, the first glass member and the third glass 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 third glass members are light transmissive because they are disposed at positions different from the positions through which the light emitted from the light emitting element and imaged by the lens passes. The first glass member and the third glass member do not adversely affect light that enters the lens from the light emitting element.

  The first lens array has a substrate made of the same material as the first glass member, the second lens array has a substrate made of the same material as the second glass member, and the second The glass member may be disposed in contact with the substrate of the first lens array, and may be disposed in contact with the substrate of the second lens array on a surface facing the first lens array. . According to this configuration, since the substrates of the first lens array and the second lens array are made of the same material as the first and second glass members, the surfaces of the substrates are formed with high accuracy. Can be easily done. Therefore, since the second glass member is disposed in contact with each substrate of each lens array, the first lens array and the second lens array are more reliably supported in parallel with each other. be able to.

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 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). 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, two rows are arranged at positions deviating from the light emitting element group EG (or the first lens LS1 and the second lens LS2) to 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 spacer SP1 disposed on both sides of the width direction LTD is wider than the interval in the width direction LTD of the second spacer SP2 disposed on both sides of the width direction LTD. The interval includes the latter interval inside the width direction LTD. 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 is positioned on the left side (that is, on 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 plane of the second spacer SP2 made of glass is in contact with the first lens array LA1 and the second lens array LA2, and supports the second lens array LA2. Yes. Since glass can easily form a high-precision plane, the first lens array LA1 can be obtained by bringing the high-precision plane of the second spacer SP2 into contact with the first lens array LA1 and the second lens array LA2, respectively. The second lens array LA2 can be supported in parallel with high accuracy. Further, since glass can easily form a highly accurate rectangular cross section, the distance between the first lens array LA1 and the second lens array LA2 can be kept constant with high accuracy by the second spacer SP2 made of glass. . Therefore, the optical axes OA of the lenses LS1 of the first lens array LA1 and the lenses LS2 of the second lens array LA2 can be reliably matched. Further, the plane of the first spacer SP1 made of glass is in contact with the head substrate 293 and the first lens array LA1 to support the first lens array LA1. Since glass can easily form a high-precision plane, the head substrate 293 and the first lens can be formed by bringing the high-precision plane of the first spacer SP1 into contact with the head substrate 293 and the first lens array LA1, respectively. The arrays LA1 can be supported in parallel with each other with high accuracy. Further, since glass can easily form a highly accurate rectangular cross section, the distance between the head substrate 293 and the first lens array LA1 can be kept constant with high accuracy by the first spacer SP1 made of glass. Therefore, the positional relationship between the light emitting element E of the head substrate 293 and the lens LS1 of the first lens array LA1 can be stabilized. Thus, according to this embodiment, it is possible to realize good exposure.

  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 light emitting element substrate 293 and the light emitting element E correspond to the “light emitting element array” of the present invention, and the photosensitive drum 21 corresponds to the “latent image carrier” of the present invention. The line head 29 corresponds to the “exposure head” of the present invention, and the head substrate 293 corresponds to the “light emitting element substrate” of the present invention. Further, the second spacer SP2 on one side (for example, the right side in FIG. 5) in the width direction LTD corresponds to the “glass member” of the present invention. Further, the first spacer SP1 on one side of the width direction LTD (for example, the right side in FIG. 5) corresponds to the “first glass 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 “third glass 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 “second glass member” of the present invention, and the other The second spacer SP2 on the side (left side in FIG. 5) corresponds to the “fourth glass 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 (9)

A first lens array having lenses;
A glass member disposed in contact with the first lens array;
A second lens array disposed in contact with the glass member on a surface facing the first lens array;
An optical unit comprising: The first lens array has a substrate made of the same material as the glass member,
The second lens array has a substrate made of the same material as the glass member,
The glass member is disposed in contact with the substrate of the first lens array, and is disposed in contact with the substrate of the second lens array on a surface facing the first lens array. The optical unit according to claim 1. 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 glass member disposed in contact with the light emitting element substrate;
A first lens array supported by a surface of the first glass member facing the light emitting element substrate and having a lens for imaging light emitted from the light emitting element;
A second glass member disposed in contact with the first lens array;
A second lens array supported by a surface of the second glass member facing the first lens array;
An exposure head comprising: The light emitting element substrate is a light transmissive member,
The exposure head according to claim 3, wherein light emitted from the light emitting element passes through the light emitting element substrate and forms an image with the lens. The first glass member is disposed in contact with the light emitting element substrate in a second direction orthogonal to or substantially orthogonal to the first direction, and the first glass member is disposed on the surface facing the light emitting element substrate. A third glass member disposed in contact with the lens array;
The third glass member is disposed in contact with the first lens array in a third direction orthogonal to the first direction and the second direction, and the first lens array A fourth glass member disposed in contact with the second lens array on the opposing surface;
The exposure head according to claim 3, further comprising:   The distance in the second direction between the first glass member and the third glass member is greater than the distance in the second direction between the second glass member and the fourth glass member. The exposure head according to claim 5, which is wide.   The said 1st glass member and the said 3rd glass member are arrange | positioned in the position different from the position through which the light light-emitted by the said light emitting element and imaged with the said lens passes. The exposure head according to any one of the above. The first lens array has a substrate made of the same material as the first glass member,
The second lens array has a substrate made of the same material as the second glass member,
The second glass member is disposed in contact with the substrate of the first lens array, and is disposed in contact with the substrate of the second lens array on a surface facing the first lens array. 8. The exposure head according to claim 3, wherein the exposure head is formed. 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, and a first glass member arranged in contact with the light emitting element substrate A first lens array having a lens which is supported on a surface of the first glass member facing the light emitting element substrate and forms an image of light emitted from the light emitting element; A second glass member disposed in contact therewith, and a second lens array supported on the second glass member on a surface facing the first lens array, and exposing the latent image carrier. An exposure head for forming 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:

Images