JP2011070099A - Exposure head, image forming apparatus, and lens module for the exposure head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique that prevents displacement of a lens and achieves satisfactory exposure. <P>SOLUTION: The exposure head includes: a resin layer where a resin lens is formed; lens array that has a glass substrate where the resin layer is arranged; a light-permieable supporting substrate that supports the glass substrate from an opposite side of the resin layer. Ends of the glass substrate protrude from the supporting substrate when seen from the optical direction of the lens. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an exposure head using a lens array, an image forming apparatus, and a lens module for the exposure head.

  Patent Document 1 proposes that an exposure head is configured using a lens array in which a plurality of lenses are arranged in an array in the longitudinal direction. That is, in this exposure head, a light emitting element is arranged to face each lens of the lens array, and light emitted from the light emitting element passes through the lens and is irradiated as a spot onto the exposed surface. Thus, the exposed surface can be exposed by the exposure head.

  Further, Patent Document 1 proposes that a long lens array is configured by arranging a plurality of lens arrays in the longitudinal direction. The reason for configuring such a long lens array is as follows. In other words, the lens array used in the exposure head needs to have a length corresponding to the application. For example, when a latent image is formed on a photoconductor in an image forming apparatus, the lens array corresponds to the width of the latent image. In order to expose the area, the lens array had to have a length corresponding to the width of the latent image. While there is such a demand, it is difficult to realize a long lens array with an integrated configuration. Therefore, in Patent Document 1, a plurality of lens arrays are arranged in the longitudinal direction to constitute one long lens array (exposure head lens module).

JP 2009-037199 A JP 2005-276849 A

  By the way, for example, by applying the technique described in Patent Document 2, the above-described lens array can be formed of a glass substrate and a resin layer. Specifically, in this lens array, a resin layer in which a plurality of resin lenses are formed is formed on a glass substrate. However, in the lens array in which the resin layer is formed on the glass substrate as described above, the following problems may occur.

  That is, since glass and resin have different linear expansion coefficients, stress is generated at the interface between the glass substrate and the resin layer depending on the temperature change of the surrounding environment. When such stress acts in the vicinity of the lens, the lens array is bent in the vicinity of the lens, and as a result, the position of the lens may fluctuate. And since the position of the lens fluctuated in this way, the position of the spot is shifted or the spot is blurred, and there are cases where good exposure cannot be realized.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a technique capable of realizing good exposure by suppressing the positional variation of the lens.

  In order to achieve the above object, an exposure head according to the present invention includes a resin layer on which a resin lens is formed, a lens array having a glass substrate on which the resin layer is disposed, and glass from the opposite side of the resin layer. And a light transmissive support substrate that supports the substrate, and an end of the glass substrate protrudes from the support substrate when viewed from the optical axis direction of the lens.

  In addition, the lens module for an exposure head according to the present invention supports a glass substrate from a side opposite to the resin layer, and a lens array having a resin layer on which a resin lens is formed and a glass substrate on which the resin layer is disposed. And a glass substrate projecting from the support substrate when viewed from the optical axis direction of the lens.

  In order to achieve the above object, an image forming apparatus according to the present invention supports a glass substrate from a side opposite to the lens array in which a resin layer on which a resin lens is formed is disposed on the glass substrate. An exposure head having a light-transmitting support substrate and a light-emitting element, and an image carrier that is irradiated with light emitted from the light-emitting element and transmitted through the lens and the support substrate, and viewed from the optical axis direction of the lens The glass substrate protrudes from the support substrate.

  In the invention thus configured (exposure head, exposure head lens module, image forming apparatus), a support substrate for supporting the glass substrate from the opposite side of the resin layer is provided. The glass substrate protrudes from the support substrate when viewed from the optical axis direction of the lens, in other words, the region where the support substrate and the glass substrate overlap with each other when viewed from the optical axis direction, However, the ends of the support substrate are arranged as a boundary. In other words, in the present invention, the support substrate and the glass substrate overlap with each other, and the relatively thick region and the relatively thin region without overlapping each other are arranged with the end of the support substrate as a boundary. In such a configuration in which the thickness is changed, the stress tends to concentrate near the portion where the thickness changes, that is, near the end of the support substrate. Therefore, even if stress occurs between the glass substrate and the resin layer having different linear expansion coefficients due to temperature changes in the surrounding environment, this stress is concentrated near the edge of the support substrate, The acting stress is kept small. That is, according to the present invention, the stress acting on the vicinity of the lens is kept small by concentrating the stress on a region other than the vicinity of the lens. As a result, it is possible to suppress the deflection of the lens array in the vicinity of the lens, suppress the lens position fluctuation, and realize good exposure.

  Moreover, you may comprise so that the both ends of a glass substrate may protrude from a support substrate seeing from the optical axis direction of a lens. In such a configuration, the thickness change described above exists in the vicinity of both ends of the support substrate. Therefore, by concentrating the stress in the vicinity of both ends of the support substrate, the stress acting in the vicinity of the lens can be kept small. Therefore, it is possible to suppress the deflection of the lens array in the vicinity of the lens, suppress the position variation of the lens, and realize good exposure.

  In addition, it is preferable to apply the present invention to a configuration in which both ends of the resin layer protrude from the support substrate when viewed from the optical axis direction of the lens. That is, in a configuration in which both ends of the resin layer protrude from the support substrate as viewed from the optical axis direction of the lens, in other words, in a configuration in which the area of the resin layer is relatively large as viewed from the optical axis direction of the lens, the resin layer and the glass A large stress may be generated between the substrate and the lens, and as a result, the lens position variation as described above may become remarkable. Therefore, for such a configuration, it is preferable to apply the present invention to surely suppress the lens position fluctuation and achieve good exposure.

  Note that glass can be used as the above-described support substrate.

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 partial perspective view which shows the outline of a line head. The partial top view which planarly viewed the head board | substrate from thickness direction TKD. The fragmentary sectional view in the AA of a line head. AA line sectional view showing typically composition of a long lens array. The partial top view which shows typically the structure of a long lens array. The longitudinal direction fragmentary sectional view which shows a head substrate and a elongate lens array typically. The graph for showing the effect of the present invention. FIG. 10 is a diagram for illustrating positions corresponding to points P1 to P6 on the horizontal axis in FIG. 9;

  FIG. 1 is a diagram showing 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 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 partial perspective view showing an outline 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 (the 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 following description of the embodiment, the downstream side (upper side in FIG. 3) in the thickness direction TKD 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). Side) 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.

  The thickness direction TKD is parallel to the optical axis OA (FIG. 6) of the imaging optical system formed by the lenses LS1 of the lens array LA1 and the lenses LS2 of the lens array LA2 described later. Here, the optical axis is defined as follows. In many cases, the imaging optical system is plane-symmetric (mirror symmetry) with respect to a plane of symmetry perpendicular to the main scanning direction MD, and is plane-symmetric (mirror reflection) with respect to a plane of symmetry perpendicular to the sub-scanning direction SD. . As described above, the imaging optical system has the first symmetry plane perpendicular to the main scanning direction and the second symmetry plane perpendicular to the sub-scanning direction SD perpendicular to the main scanning direction MD. The line of intersection of the second symmetry plane is determined. When the imaging optical system is rotationally symmetric, the intersection line of the first symmetric surface and the second symmetric surface coincides with the optical axis. If the imaging optical system is not rotationally symmetric, strictly speaking, the optical axis of the imaging optical system may not be defined. In such a case, the above-described intersection line may be handled as the optical axis.

  The line head 29 has a schematic configuration in which a head substrate 293, a light shielding member 297, a lens array LA1 and a lens array LA2 are arranged in this order in the thickness direction TKD. Then, 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 as a spot ST by the lenses LS1 and LS2 of the lens arrays LA1 and LA2 (FIG. 5). Next, the detailed configuration of each member will be described.

  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 taken along line AA of the line head, 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 shows the respective geometries of three light emitting element groups EG (or three lenses LS1, etc.) arranged in a line with a distance Dg in the longitudinal direction LGD and a distance Dt in the width direction LTD. It passes through the center of gravity (or the center of each lens). A direction Dlsc shown in FIG. 4 is a direction parallel to the line AA. Further, in FIG. 4, in order to show the positional relationship between the light emitting element group EG formed on the head substrate 293, the lens LS1 formed on the lens array LA1, and the lens LS2 formed on the lens array LA2, the lens LS1 and the lens LS2 are shown. Are also indicated by alternate long and short dash lines. Incidentally, the description about the lens LS1 and the lens LS2 is for showing the positional relationship between them, and shows that the lens LS1 and the lens LS2 are formed on the back surface 293-t (FIG. 5) of the head substrate. It is not a thing. 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. Then, 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.

  As described above, the plurality of light emitting element groups EG are two-dimensionally and discretely 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 plurality of light guide holes 2971 penetrating in the thickness direction TKD. Each light guide hole 2971 has a circular shape in plan view from the thickness direction TKD, and black plating is applied to the inner wall thereof. 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 is incident only on the imaging optical systems LS1 and LS2 provided in the light emitting element group EG which is its own emission source, and is imaged. However, some of the light beams may become stray light without being directed to the imaging optical systems LS1 and LS2 provided in the light emitting element group EG that is the emission source. If such stray light enters the imaging optical systems 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 imaging optical systems 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. Become. As a result, the above-described ghost can be suppressed and a good exposure operation can be realized.

  As described above, the lens arrays LA1 and LA2 are provided on one side of the head substrate 293 and the light shielding member 297 in the thickness direction TKD. In order to increase the length of the line head 29 of this embodiment, a plurality of lens arrays LA1 are arranged in the longitudinal direction LGD to form one long lens array L-LA1, and the lens array LA2 is disposed in the longitudinal direction. A plurality of long lens arrays L-LA2 are arranged side by side on the LGD. These long lens arrays L-LA1 and L-LA2 are arranged in the thickness direction TKD. Next, the configuration of the long lens arrays L-LA1 and L-LA2 will be described in detail with reference to FIGS.

  FIG. 6 is a cross-sectional view taken along line AA schematically showing the configuration of the long lens array, and corresponds to a case where the cross section is viewed from the longitudinal direction LGD (main scanning direction MD). FIG. 7 is a partial plan view schematically showing the configuration of the long lens array. Each of the long lens arrays L-LA1 and L-LA2 has a configuration in which a lens array LA composed of a glass substrate SB, a resin layer PL, and a resin lens LS is attached to a support glass SS. Therefore, in the schematic diagram shown in the present embodiment, the constituent members of the long lens array L-LA1 are represented by adding a number “1” to each member (SB, PL, LS, LA, SS) (SB1, (PL1, LS1, LA1, SS1) and the constituent members of the long lens array L-LA2 are represented by adding a number “2” to each member (SB, PL, LS, LA, SS) (SB2, PL2 , LS2, LA2, SS2).

  The lens array LA1 (LA2) includes a glass substrate SB1 (SB2) having a parallelogram shape whose end in the longitudinal direction LGD is cut obliquely (parallel to the direction Dlsc), and other than this glass substrate SB1 (SB2) And a resin layer PL1 (PL2) formed by being laminated on the surface SB-t. A resin lens LS1 (LS2) is formed on the resin layer PL1 (PL2). More specifically, a plurality of resin lenses LS1 (LS2) arranged in a zigzag pattern in the longitudinal direction LGD are integrally formed with the resin layer PL1 (PL2) in the resin layer PL1 (PL2) PL2. . Thus, the plurality of light emitting element groups EG and the plurality of lenses LS1 (LS2) face each other in the thickness direction TKD in a one-to-one correspondence relationship. The resin layer PL1 (PL2) can be made of, for example, a photocurable resin.

  As shown in FIG. 7, a plurality of lens arrays LA1 (LA2) are arranged in the longitudinal direction LGD to form a long lens array L-LA1 (L-LA2). The long lens array L-LA1 (L-LA2) includes a supporting glass SS1 (SS2) having a flat plate shape that is long in the longitudinal direction LGD, and the other surface SS- of the supporting glass SS1 (SS2). One surface SB-h of the glass substrate SB1 (SB2) of each lens array LA1 (LA2) is fixed to t by an adhesive or the like. Thus, the plurality of lens arrays LA1 (LA2) arranged in the longitudinal direction LGD are supported by the support glass SS1 (SS2) in a state where they are positioned with respect to each other.

  The lengths Wpl, Wsb, and Wss in the width direction LTD of the resin layer PL1 (PL2), the glass substrate SB1 (SB2), and the support glass SS1 (SS2) satisfy the formula Wsb> Wpl> Wss. That is, the glass substrate SB1 (SB2) has the widest width Wsb in the width direction LTD, the resin layer PL1 (PL2) has the next widest width Wpl in the width direction LTD, and the support glass SS1 (SS2) has the width direction. It has the narrowest width Wss in LTD. A resin layer PL1 (PL2), a glass substrate SB1 (SB2), and a support glass SS1 (SS2) that satisfy such a width relationship are laminated in this order in the thickness direction TKD. As a result, when viewed from the optical axis direction OA (thickness direction TKD), both ends of the glass substrate SB1 (SB2) in the width direction LTD protrude from both ends of the width direction LTD of the support glass SS1 (SS2) in the width direction LTD. Yes. Further, when viewed from the optical axis direction OA (thickness direction TKD), both ends of the resin layer PL1 (PL2) in the width direction LTD protrude from both ends of the support glass SS1 (SS2) in the width direction LTD in the width direction LTD. . Further, when viewed from the optical axis direction OA (thickness direction TKD), both ends of the glass substrate SB1 (SB2) in the width direction LTD protrude from both ends of the resin layer PL1 (PL2) in the width direction LTD in the width direction LTD. .

  As shown in FIG. 8, the head substrate 293 and the above-described long lens arrays L-LA1 and L-LA2 are arranged in the thickness direction TKD while being spaced apart from each other. Here, FIG. 8 is a partial sectional view in the longitudinal direction schematically showing the positional relationship between the head substrate and the long lens array. As shown in FIG. 8, spacers SP <b> 1 are disposed at both ends in the longitudinal direction LGD of the head substrate 293. A long lens array L-LA1 is installed on these spacers SP1 and SP1. Incidentally, as shown in FIG. 7, in the long lens array L-LA1, both ends of the support glass SS1 in the longitudinal direction LGD protrude from the lens arrays LA1, LA1,... In the longitudinal direction LGD, and the spacers SP1, SP1 are supported. The long lens array L-LA1 is supported in contact with the protruding portion (the back surface thereof) of the glass SS1. The spacer SP1 is fixed to the head substrate 293 and the long lens array L-LA1 with an adhesive or the like. Thus, the head substrate 293 and the long lens array L-LA1 are positioned and fixed to each other. Incidentally, at this time, the long lens array L-LA1 is supported with a slight gap in the thickness direction TKD with respect to the light shielding member 297.

  Further, as shown in FIG. 8, spacers SP2 are disposed at both ends in the longitudinal direction LGD of the support glass SS1 included in the long lens array L-LA1. A long lens array L-LA2 is installed on these spacers SP2 and SP2. Incidentally, as shown in FIG. 7, in the long lens array L-LA2, both ends of the supporting glass SS2 in the longitudinal direction LGD protrude from the lens arrays LA2, LA2,... In the longitudinal direction LGD, and the spacers SP2, SP2 are supported. The long lens array L-LA2 is supported in contact with the protruding portion (the back surface thereof) of the glass SS2. The spacer SP2 is fixed to each of the long lens array L-LA1 and the long lens array L-LA2 with an adhesive or the like. Thus, the long lens array L-LA1 and the long lens array L-LA2 are positioned and fixed to each other.

  In this embodiment, the lens LS1 and the lens LS2 facing each other in the thickness direction TKD constitute one imaging optical system. That is, the curvatures of the lenses LS1 and LS2 are adjusted so as to realize desired optical characteristics, and the lenses LS1 and LS2 having different lens shapes cooperate to form a single imaging optical system. Function. Specifically, this imaging optical system forms an inverted reduced image, and its lateral magnification is negative and has an absolute value of less than 1. Then, the light beam emitted from the light emitting element E passes through the lenses LS1 and LS2, and then is irradiated onto the surface of the photosensitive drum 21 as a spot ST (FIG. 5). 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.

  As described above with reference to FIG. 6 and the like, in the long lens array L-LA1 (L-LA2) of this embodiment, the support for supporting the glass substrate SB1 (SB2) from the opposite side of the resin layer PL1 (PL2). Glass SS1 (SS2) is provided. The glass substrate SB1 (SB2) protrudes from the support glass SS1 (SS2) when viewed from the optical axis direction OA of the lens LS1 (LS2), in other words, the support glass SS1 (SS2) when viewed from the optical axis direction OA. ) And the glass substrate SB1 (SB2) and the non-overlapping region are aligned with the end EP of the supporting glass SS1 (SS2) as a boundary. That is, in this embodiment, the supporting glass SS1 (SS2) and the glass substrate SB1 (SB2) overlap with each other and a relatively thick region, and a region with a relatively thin thickness without overlapping these, The supporting glass SS1 (SS2) is arranged with the end EP as a boundary. In such a configuration in which the thickness is changed, stress tends to concentrate in the vicinity of the portion where the thickness changes, that is, in the vicinity of the end EP of the support glass SS1 (SS2). Therefore, even if a stress is generated between the glass substrate SB1 (SB2) and the resin layer PL1 (PL2) having different linear expansion coefficients due to the temperature change of the surrounding environment, this stress is supported by the supporting glass SS1 (SS2). Therefore, the stress acting in the vicinity of the lens LS1 (LS2) can be kept small. In other words, the long lens array L-LA1 (L-LA2) of this embodiment keeps the stress acting on the lens vicinity LS1 (LS2) small by concentrating the stress on a region other than the vicinity of the lens LS1 (LS2). ing. As a result, it is possible to suppress the deflection of the lens array LA1 (LA2) in the vicinity of the lens LS1 (LS2), suppress the positional fluctuation of the lens LS1 (LS2), and realize good exposure.

  Further, in the long lens array L-LA1 (L-LA2) of this embodiment, both ends of the glass substrate SB1 (SB2) protrude from the support glass SS1 (SS2) when viewed from the optical axis direction OA of the lens LS1 (LS2). It has the structure which did. In such a configuration, the above-described change in thickness exists near both ends EP and EP of the supporting glass SS1 (SS2). Accordingly, by concentrating the stress in the vicinity of both ends EP and EP of the support glass SS1 (SS2), the stress acting in the vicinity of the lens LS1 (LS2) can be kept small. Therefore, it is possible to suppress the deflection of the lens array LA1 (LA2) in the vicinity of the lens LS1 (LS2), suppress the positional fluctuation of the lens LS1 (LS2), and realize good exposure.

  Further, as in the present embodiment, the present invention is applied to a configuration in which both ends of the resin layer PL1 (PL2) protrude from the support glass SS1 (SS2) when viewed from the optical axis direction OA of the lens LS1 (LS2). It is preferable to apply. That is, both ends of the resin layers PL1 and PL2 protrude from the support substrate when viewed from the optical axis direction OA of the lens LS1 (LS2), in other words, the resin layer when viewed from the optical axis direction OA of the lens LS1 (LS2). In a configuration in which the area of PL1 (PL2) is relatively wide, a large stress may be generated between the resin layer PL1 (PL2) and the glass substrate SB1 (SB2). As a result, the lens LS1 (LS2) as described above may be generated. ) May become noticeable. Therefore, by applying the present invention to such a configuration, it is preferable to achieve a good exposure by reliably suppressing the positional fluctuation of the lens LS1 (LS2).

  By the way, in the above-described embodiment, a long lens array L-LA1 (L-LA2) is configured by arranging a plurality of lens arrays LA1 (LA2) in the longitudinal direction LGD. In such a long lens array L-LA1 (L-LA2), the lens arrays LA1 (LA2) are aligned in a plane perpendicular to the optical axis direction OA, and the lens arrays LA1 (LA2) are aligned. It is preferable that there is no step between them (that is, there is no deviation in the optical axis direction OA). This is because if the lens arrays LA1 (LA2) are shifted from each other in the optical axis direction OA, the position of the lens LS1 (LS2) of each lens array LA1 (LA2) is shifted in the optical axis direction OA. This is because exposure may not be possible. On the other hand, in this embodiment, each lens array LA1 (LA2) is supported by a supporting glass SS1 (SS2), that is, a glass flat plate. Therefore, by assembling the long lens array L-LA1 (L-LA2) as follows, the lens arrays LA1 (LA2) can be arranged on the same plane in the plane perpendicular to the optical axis direction OA. It is easy to execute.

  That is, a base having a plane with a desired flatness is prepared, and the support glass SS1 (SS2) is placed on the base (on the vertical direction). Since the support glass SS1 (SS2) is made of glass, the front surface SS-h and the back surface SS-t of the support glass SS1 (SS2) can be formed so as to have a flatness within a desired value range. Therefore, when the support glass SS1 (SS2) is placed on the base plane with the front surface SS-h down, the support glass SS1 with the back surface SS-t having relatively good flatness facing upward. (SS2) will be arranged. Then, by arranging a plurality of lens arrays LA1 (LA2) on the supporting glass back surface SS-t, the lens arrays LA1 (LA2) can be easily arranged on the same plane.

Others As described above, in the above embodiment, the long lens array L-LA1 (L-LA2) corresponds to the “lens module for exposure head” of the present invention, and the line head 29 corresponds to the “exposure head” of the present invention. Equivalent to. The photosensitive drum 21 corresponds to the “image carrier” of the present invention. The lens LS1 (LS2) corresponds to the “lens” of the present invention, the resin layer PL1 (PL2) corresponds to the “resin layer” of the present invention, and the lens array LA1 (LA2) of the present invention “lens array”. The support glass SS1 (SS2) corresponds to the “support substrate” of the present invention. The optical axis direction OA corresponds to the “lens optical axis direction” 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 long lens array L-LA1 (L-LA2) is supported by the spacer SP1 (SP2) at the end in the longitudinal direction LGD, but the long lens array L-LA1 (L-LA2) is supported. ) Is not limited to this.

  In the above embodiment, the shape and size of each member (glass substrate SB1, SB2, support glass SS1, SS2, etc.) are shared by the long lens arrays L-LA1, L-LA2. However, the shape and dimensions of these members may be different between the long lens arrays L-LA1 and L-LA2.

  In the above embodiment, both ends of the resin layer PL1 (PL2) protrude from the support glass SS1 (SS2) when viewed from the optical axis direction OA of the lens LS1 (LS2), but both ends of the resin layer PL1 (PL2) The support glass SS1 (SS2) may be configured so as to fit inside the both ends.

  In the above-described embodiment, the present invention is applied to both the long lens arrays L-LA1 and L-LA2. However, only one of the long lens arrays in which the positional variation of the lens is particularly problematic is used. The present invention may be applied.

  Further, the number of long lens arrays can be changed, and only one lens may be provided, or three or more may be arranged in the optical axis direction OA.

  In the above embodiment, a glass flat plate (support glass SS1 (SS2)) is used to support the lens array LA1 (LA2). However, a member other than glass is used as the member that supports the lens array LA1 (LA2). Can also be configured.

  Various changes can be made to the shape and dimensional relationship of each member such as the lens arrays LA1 and LA2.

  In addition, the imaging optical system of the above embodiment forms a reverse image, but may form a normal rotation image (that is, an image that is not reversed).

  In addition, the imaging optical system of the above embodiment forms a reduced image, but may form an equal-magnification image or an enlarged image.

  In the above embodiment, the lens array LA1 (LA2) is arranged so that the lens LS1 (LS2) is convex toward the light emitting element E. Conversely, the lens LS1 (LS2) is on the photosensitive drum 21 side. The lens array LA1 (LA2) may be arranged so as to be convex.

  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.

  Moreover, in the said 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.

  Next, examples of the present invention will be shown. However, the present invention is not limited by the following examples as a matter of course, and it is of course possible to implement the present invention with appropriate modifications within a range that can meet the gist of the preceding and following descriptions. They are all included in the technical scope of the present invention.

  FIG. 9 is a graph for illustrating the effect of the present invention. The horizontal axis of the figure shows the positions in the width direction LTD of the points P1 to P6 (FIG. 10) of the long lens array L-LA2, and the vertical axis of the figure shows the points P1 to P6 (FIG. 10). The position in the optical axis direction OA is shown. FIG. 10 is a diagram for illustrating positions corresponding to the respective points P1 to P6 on the horizontal axis in FIG. 9, and shows a cross section along line AA schematically showing the configuration of the long lens array in the longitudinal direction LGD ( This corresponds to the case of viewing from the main scanning direction MD). As shown in FIG. 10, the points P1 and P6 are located at both ends of the glass substrate SB2. The points P2 and P5 are located at both ends of the three lenses LS2, LS2, and LS2 arranged in the AA line direction (direction Dlsc). The points P3 and P4 are located between the three lenses LS2, LS2, and LS2 arranged in the AA line direction (direction Dlsc).

  In FIG. 9, the long lens array L-LA2 is configured to satisfy the width Wsb> the width Wss (relational expression 1), and the long lens so as to satisfy the width Wsb = the width Wss (relational expression 2). The case where the array L-LA2 is configured is shown. More specifically, in FIG. 9, the light at each point P1 to P6 of the long lens array L-LA2 that satisfies the relational expression 1 when the ambient temperature is changed after the glass substrate SB2 and the supporting glass SS2 are bonded together. The axial position (square dots) and the optical axis positions (triangular dots) of the points P1 to P6 of the long lens array L-LA2 satisfying the relational expression 2 are plotted. At the time when the glass substrate SB2 and the supporting glass SS2 are bonded together, the points P1 to P6 are the long lens array L-LA2 satisfying the relational expression 1 and the long lens array L-LA2 satisfying the relational expression 2. Is the same (diamond dot).

  For the long lens array L-LA2 satisfying the width Wsb = width Wss (relational expression 2), the points P1 and P6 on both ends of the glass substrate SB2 and the three lenses LS2 and LS2 are compared when the pasting time and the temperature change are compared. It can be seen that the positions P2 and P5 at both ends of LS2 are greatly displaced in the optical axis direction OA. This is because the stress generated in the long lens array L-LA2 due to the temperature change acts in the vicinity of the lenses LS2, LS2, and LS2, and the lens array LA2 is bent in the vicinity of the lenses LS2, LS2, and LS2. It is thought that

  Subsequently, regarding the long lens array L-LA2 satisfying the width Wsb> width Wss (relational expression 1), when the pasting time and the temperature change are compared, the points P1 and P6 at both ends of the glass substrate SB2 are in the optical axis direction OA. However, it can be seen that position fluctuations in the optical axis direction of the points P2 to P5 near the lenses LS2, LS2, and LS2 are suppressed. This is because stress is concentrated in the vicinity of both ends EP and EP of the support glass SS2, thereby suppressing the stress acting in the vicinity of the lenses LS2, LS2, and LS2, and as a result, the lenses in the vicinity of the lenses LS2, LS2, and LS2. This is considered to be because the deflection of the array LA2 is suppressed.

  29: Line head, L-LA1, L-LA2: Long lens array, LA1, LA2 ... Lens array, LS1, LS2 ... Lens, SB1, SB2 ... Glass substrate, SS1, SS2 ... Support glass, LGD: Longitudinal direction, LTD ... Width direction

Claims (6)

A resin layer on which a resin lens is formed, and a lens array having a glass substrate on which the resin layer is disposed;
A light-transmissive support substrate that supports the glass substrate from the opposite side of the resin layer;
With
An exposure head, wherein an end of the glass substrate protrudes from the support substrate when viewed from the optical axis direction of the lens.   The exposure head according to claim 1, wherein both ends of the glass substrate protrude from the support substrate when viewed from the optical axis direction of the lens.   The exposure head according to claim 1, wherein both ends of the resin layer protrude from the support substrate when viewed from the optical axis direction of the lens.   The exposure head according to claim 1, wherein the support substrate is made of glass. A resin layer on which a resin lens is formed, and a lens array having a glass substrate on which the resin layer is disposed;
A light-transmissive support substrate that supports the glass substrate from the opposite side of the resin layer;
With
The lens module for an exposure head, wherein the glass substrate protrudes from the support substrate when viewed from the optical axis direction of the lens. A lens array in which a resin layer on which a resin lens is formed is disposed on a glass substrate, a light-transmitting support substrate that supports the glass substrate from the opposite side of the resin layer, and an exposure head having a light emitting element;
An image carrier that is irradiated with light emitted from the light emitting element and transmitted through the lens and the support substrate;
With
The image forming apparatus, wherein the glass substrate protrudes from the support substrate when viewed from the optical axis direction of the lens.

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