Exposure device manufacturing method and exposure device

Abstract

To provide a manufacturing method and device that can prevent interference between a cleaning rod used for cleaning a lens array and an adhesive even when the lens array is fixed to the housing via the adhesive.SOLUTION: An exposure head includes: a substrate; a plurality of LEDs provided on the substrate; a lens array that focuses light emitted from the plurality of LEDs onto an illuminated surface; and a housing that holds the substrate and the lens array. The housing is formed with: a first opening; and a second opening that is larger in an opening area than the first opening. The housing holds the lens array in a state of passing through the first opening, and also holds the substrate at a position closer to the second opening than the lens array. An exposure device manufacturing method includes: a first step of applying an adhesive between the lens array and the housing from the second opening side with the lens array positioned in the first opening, and fixing the lens array to the housing via the adhesive; and a second step of fixing the substrate to the housing after the first step.SELECTED DRAWING: Figure 16

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing an exposure device that exposes an irradiation surface such as the surface of a photosensitive member, and to an exposure device. [Background technology]

[0002] A common electrophotographic image forming device is one that forms an electrostatic latent image on the surface of a photosensitive member by exposing the surface of the photosensitive member to light using an exposure device equipped with an LED array and a lens array as multiple light-emitting elements, and then develops the toner image by attaching toner to the electrostatic latent image (for example, Patent Document 1).

[0003] In such an exposure device, the substrate on which the LED array is mounted and the lens array are adhered to a holding member via adhesive, etc. The exposure device is assembled by, for example, using a tool to adjust the positions of the substrate on which the LED array is mounted and the lens array so that the optical characteristics meet predetermined standards, while fixing the substrate and the lens array to the holding member.

[0004] For example, Patent Document 2 discloses a manufacturing method in which a lens array is fixed to a holding member and then a substrate is fixed. In Patent Document 2, electrode pads that can pass electricity to an LED array are formed on the substrate, and after the lens array is fixed to the holding member, the substrate is held with a tool and positioned relative to the holding member while passing electricity through the electrode pads to the LED array. At this time, light emitted from the LED array toward the lens array is received by a camera to determine the position of the substrate. Then, the substrate and holding member are fixed with an adhesive. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-62853 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-49713 Summary of the Invention [Problem to be solved by the invention]

[0006] In the manufacturing method described in Patent Document 2, the lens array is fixed to the holding member with an adhesive. However, when the adhesive is applied from the outside of the holding member and fixed to the lens array, the adhesive hardens around the lens array and outside the holding member. Here, the lens array emits light from its light-emitting surface toward an irradiated surface such as the surface of a photosensitive element. However, this light-emitting surface may become contaminated with toner or other contaminants. For this reason, the light-emitting surface may be cleaned with a cleaning member. The cleaning member is, for example, held by a cleaning rod as a cleaning tool. As described above, if the adhesive hardens around the lens array and outside the holding member, there is a risk that the adhesive will interfere with part of the cleaning rod during cleaning. As a result, there is a risk that the light-emitting surface will not be cleaned properly or that the adhesive will be scraped off during cleaning.

[0007] The present invention aims to provide a manufacturing method and apparatus that can prevent interference between a cleaning tool used to clean the lens array and the adhesive even when the lens array is fixed to a holding member with an adhesive. [Means for solving the problem]

[0008] One aspect of the present invention is a method for manufacturing an exposure device comprising: a substrate; a plurality of light-emitting elements provided on the substrate; a lens array that focuses light emitted from the plurality of light-emitting elements onto an irradiated surface; and a holding member having a first opening and a second opening having a larger opening area than the first opening, the holding member holding the lens array while passing through the first opening and holding the substrate at a position closer to the second opening than the lens array, the method comprising: a first step of applying adhesive between the lens array and the holding member from the second opening side while the lens array is positioned in the first opening, and fixing the lens array to the holding member with the adhesive; and a second step of fixing the substrate to the holding member after the first step.

[0009] One aspect of the present invention is an exposure device comprising: a substrate; a plurality of light-emitting elements provided on the substrate; a lens array that focuses light emitted from the plurality of light-emitting elements onto an irradiated surface; a holding member having a first opening and a second opening having a larger opening area than the first opening, the holding member holding the lens array while passing through the first opening and holding the substrate at a position closer to the second opening than the lens array; and an adhesive applied to the inside of the holding member on the second opening side between the lens array and the holding member, fixing the lens array to the holding member. [Effects of the Invention]

[0010] According to the present invention, even if the lens array is fixed to the holding member by an adhesive, interference between the adhesive and a cleaning tool used to clean the lens array can be suppressed. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic cross-sectional view showing the configuration of an image forming apparatus according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view of an exposure head according to the embodiment. [Figure 3] FIG. 2 is a perspective view of an exposure head according to the embodiment. [Figure 4] 2A and 2B are a perspective view and a cross-sectional view, respectively, of an exposure head and a photosensitive drum according to an embodiment of the present invention. [Figure 5] (a) A perspective view, (b) A plan view, (c) An enlarged plan view of a portion of (b) of a substrate according to an embodiment, (d) A plan view of a lens array according to an embodiment, and (e) A perspective view of a schematic configuration of the lens array according to an embodiment. [Figure 6] FIG. 2 is a plan view schematically showing a surface of a substrate according to an embodiment on which check pads are mounted. [Figure 7] 1A is a schematic cross-sectional view showing a state in which a lens array according to a comparative example is assembled to a housing; FIG. 1B is a schematic cross-sectional view showing a state in which the position of the lens array according to the comparative example is adjusted relative to the housing; [Figure 8](a) A schematic cross-sectional view showing the state in which adhesive is applied between the lens array and the housing in the comparative example, (b) a schematic cross-sectional view showing the state in which UV is irradiated onto the adhesive applied between the lens array and the housing in the comparative example, and (c) a schematic cross-sectional view showing the state in which the lens array in the comparative example is fixed to the housing. [Figure 9] FIG. 10A is a schematic diagram showing a state in which a substrate according to a comparative example is held by a suction pad, and FIG. 10B is a schematic diagram showing a state in which warpage of the substrate according to the comparative example is corrected by the suction pad. [Figure 10] (a) A schematic cross-sectional view showing the position adjustment state of the substrate relative to the housing in the comparative example; (b) A schematic cross-sectional view showing the state in which adhesive is being applied between the substrate and the housing in the comparative example; (c) A schematic cross-sectional view showing the state in which UV is being irradiated onto the adhesive applied between the substrate and the housing in the comparative example; (d) A schematic cross-sectional view showing the fixed state of the substrate relative to the housing in the comparative example. [Figure 11] FIG. 2 is a perspective view of a cleaning rod according to an embodiment. [Figure 12] FIG. 2 is a perspective view of one end of the cleaning rod according to the embodiment, as viewed from the front side. [Figure 13] FIG. 4 is a perspective view of one end of the cleaning rod according to the embodiment, seen from the back side. [Figure 14] FIG. 2 is a perspective view showing the relationship between an exposure head and a cleaning rod according to the embodiment. [Figure 15] 10A and 10B are schematic cross-sectional views for explaining problems that arise when cleaning an exposure head according to a comparative example with a cleaning rod. [Figure 16] 4 is a flowchart showing the sequence of a method for manufacturing an exposure head according to an embodiment. [Figure 17] (a) A schematic cross-sectional view showing the position adjustment state of the lens array of the embodiment relative to the housing; (b) A schematic cross-sectional view showing the state in which adhesive is being applied between the lens array of the embodiment and the housing; (c) A schematic cross-sectional view showing the state in which UV is being irradiated onto the adhesive applied between the lens array of the embodiment and the housing; (d) A schematic cross-sectional view showing the fixed state of the lens array of the embodiment relative to the housing. [Figure 18]1A is a schematic diagram showing how a substrate according to an embodiment is held by suction pads, and FIG. 1B is a schematic diagram showing how warpage of a substrate according to an embodiment is corrected by suction pads. [Figure 19] (a) A schematic cross-sectional view showing the position adjustment state of the substrate relative to the housing according to the embodiment; (b) A schematic cross-sectional view showing the state in which adhesive is being applied between the substrate and the housing according to the embodiment; (c) A schematic cross-sectional view showing the state in which UV is being irradiated onto the adhesive applied between the substrate and the housing according to the embodiment; (d) A schematic cross-sectional view showing the state in which the substrate is fixed to the housing according to the embodiment. [Figure 20] FIG. 10 is a perspective view of the substrate and the housing according to the embodiment bonded together with a thermosetting adhesive, as viewed from the substrate side of the exposure head. [Figure 21] FIG. 4 is a schematic cross-sectional view showing a state in which the exposure head according to the embodiment is being cleaned by a cleaning rod. DETAILED DESCRIPTION OF THE INVENTION

[0012] The embodiment will be described with reference to Figures 1 to 21. First, the schematic configuration of an image forming apparatus according to the present embodiment will be described with reference to Figure 1.

[0013] [Image forming device] 1 is a schematic cross-sectional view of an image forming apparatus 100. Although the image forming apparatus 100 is a copying machine equipped with a document reading device in this embodiment, it may be another image forming apparatus, such as a printer that does not have a document reading device. Furthermore, this embodiment is not limited to a color image forming apparatus equipped with multiple photosensitive drums as shown in FIG. 1, but may also be a color image forming apparatus equipped with a single photosensitive drum or an image forming apparatus that forms monochrome images.

[0014] The image forming apparatus 100 includes four image forming units 1Y, 1M, 1C, and 1K (hereinafter collectively referred to as "image forming units 1") that form toner images of yellow, magenta, cyan, and black, respectively. The image forming units 1Y, 1M, 1C, and 1K each include a photosensitive drum 2Y, 2M, 2C, and 2K (hereinafter collectively referred to as "photosensitive drum 2"), which is an example of a photosensitive body. The photosensitive drum 2 may be a photosensitive belt.

[0015] The image forming units 1Y, 1M, 1C, and 1K are also provided with charging rollers 3Y, 3M, 3C, and 3K (hereinafter collectively referred to as "charging rollers 3") as charging devices that charge the photosensitive drums 2Y, 2M, 2C, and 2K, respectively. The image forming units 1Y, 1M, 1C, and 1K are also provided with LED (Light Emitting Diode, hereinafter referred to as LED) exposure heads 4Y, 4M, 4C, and 4K (hereinafter collectively referred to as "exposure heads 4") as exposure devices that expose the photosensitive drums 2Y, 2M, 2C, and 2K to light.

[0016] Furthermore, the image forming units 1Y, 1M, 1C, and 1K are provided with developing units 24Y, 24M, 24C, and 24K (hereinafter collectively referred to as "developing units 24") as developing devices that develop the electrostatic latent images on the photosensitive drums 2 with toner and develop toner images of the respective colors on the photosensitive drums 2. The letters Y, M, C, and K attached to the reference numerals indicate the colors of the toner.

[0017] The image forming apparatus 100 shown in FIG. 1 is an image forming apparatus that employs a so-called "bottom exposure method" in which the photosensitive drum 2 is exposed from below, i.e., the exposure head 4 is disposed below the photosensitive drum 2. The following description will be given on the assumption that the image forming apparatus employs the bottom exposure method. Note that, although not shown, the image forming apparatus may also be configured to employ an "top exposure method" in which the photosensitive drum is exposed from above.

[0018] The image forming apparatus 100 includes an intermediate transfer belt 9 as an intermediate transfer member onto which the toner image formed on the photosensitive drum 2 is transferred, and primary transfer rollers 6Y, 6M, 6C, and 6K (hereinafter collectively referred to as "primary transfer rollers 6") that sequentially transfer the toner image formed on the photosensitive drum 2 onto the intermediate transfer belt 9. The intermediate transfer belt 9 is disposed above the image forming unit 1. Note that, in addition to the intermediate transfer method using the intermediate transfer belt 9, a direct transfer method in which an image is directly transferred from the photosensitive drum 2 to a recording material such as paper may also be used. Examples of recording materials include sheets such as plain paper, cardboard, thin paper, and plastic sheets.

[0019] The image forming apparatus 100 also includes a secondary transfer roller 16 as a transfer device that transfers the toner image on the intermediate transfer belt 9 to the recording material P conveyed from the feed unit 11 at a secondary transfer unit T2, and a fuser 19 as a fuser that fuses the secondarily transferred image onto the recording material P. The toner bottles 22Y, 22M, 22C, and 22K (hereinafter collectively referred to as "toner bottles 22") that contain replenishment toner of each color are units that can be detached from the image forming apparatus 100 and replaced. The toner bottles 22 are disposed above the intermediate transfer belt 9. The toner bottles 22 replenish the appropriate amount of toner at the appropriate time to the development units of the four image forming units by a toner replenishing mechanism (not shown) from the corresponding toner bottles.

[0020] The image forming apparatus 100 also includes a feeding unit 11 that feeds recording materials P. The feeding unit 11 has sheet cassettes 12a and 12b, feeding rollers 13a and 13b, and registration rollers 15. The sheet cassettes 12a and 12b are disposed below the image forming unit 1. The recording materials P stored in the sheet cassettes 12a and 12b are fed one by one by the feeding rollers 13a and 13b, and are transported to the secondary transfer unit T2 at a predetermined timing by the registration roller 15.

[0021] [Image formation process] Next, a brief description will be given of the image formation process of the image forming apparatus 100 described above. The charging roller 3Y charges the surface of the photosensitive drum 2Y. The exposure head 4Y exposes the surface of the photosensitive drum 2Y charged by the charging roller 3Y. As a result, an electrostatic latent image is formed on the photosensitive drum 2Y. Next, the developing unit 24Y develops the electrostatic latent image formed on the photosensitive drum 2Y with yellow toner. The yellow toner image developed on the surface of the photosensitive drum 2Y is transferred onto the intermediate transfer belt 9 by the primary transfer roller 6Y. Magenta, cyan, and black toner images are formed in a similar image formation process and transferred to the intermediate transfer belt 9 so as to be superimposed on top of each other.

[0022] The toner images of each color transferred onto the intermediate transfer belt 9 are transported by the intermediate transfer belt 9 to a secondary transfer section T2. ​​The toner images transported to the secondary transfer section T2 are transferred all at once by a secondary transfer roller 16 onto a recording material P transported from a feeding section 11. The recording material P onto which the toner images have been transferred is transported to a fixing device 19. The fixing device 19 fixes the toner images to the recording material P by heat and pressure. The recording material P that has been fixed by the fixing device 19 is discharged by a discharge roller 20 to a discharge tray 21 disposed above a toner bottle 22.

[0023] [Exposure head] Next, the exposure head 4 as an exposure device will be described with reference to FIGS. 2 and 3. FIG. 2 is a schematic cross-sectional view of the exposure head 4 provided in the image forming apparatus 100 of this embodiment, and is a view of the exposure head 4 cut in a direction perpendicular to the longitudinal direction. FIG. 3 is a perspective view of the exposure head 4 as seen from above. The exposure head 4 has an elongated shape (longitudinal shape) extending in the direction of the rotation axis of the photosensitive drum 2. Specifically, the photosensitive drum 2 is disposed so that the rotation axis direction is the front-rear direction of the image forming apparatus 100 (the FB direction indicated by the arrow in FIG. 3), and the exposure head 4 is also disposed so that its longitudinal direction is the front-rear direction, as shown in FIG. 3. The front side (F side) of the image forming apparatus 100 is the side where the device is operated, for example, the side where an operation unit such as an operation panel through which a user operates the image forming apparatus 100 is located. The rear side (B side) of the image forming apparatus 100 is the side opposite the front side, i.e., the rear side of the image forming apparatus 100.

[0024] 2, the exposure head 4 has a substrate 50, a light-emitting element group 51 mounted on the substrate 50, a lens array 52, a housing 54 serving as a holding member for holding the substrate 50 and the lens array 52, and a housing support member 55 for supporting the housing 54. As shown in FIGS. 5(a) to 5(c) described below, the light-emitting element group 51 is an LED array composed of a plurality of LED (Light Emitting Diode) chips 53. That is, in the case of this embodiment, the exposure head 4 is equipped with a plurality of LED chips 53 as a plurality of light-emitting elements that emit light. The substrate 50, the lens array 52, and the housing 54 each have an elongated shape extending in the FB direction, and the light-emitting element group 51 is arranged on the substrate 50 along the FB direction.

[0025] [Exposure head positioning] Next, the positioning of the exposure head 4 relative to the photosensitive drum 2 will be described with reference to FIG. 3 and FIGS. 4(a) and 4(b). FIG. 4(a) is a perspective view that schematically shows a state in which the exposure head 4 is positioned relative to the photosensitive drum 2. FIG. 4(b) is a cross-sectional view that schematically shows a state in which the exposure head 4 is positioned relative to the photosensitive drum 2. First, the positioning pins 45F and 45B of the exposure head 4 will be described. As shown in FIG. 3, the housing 54 of the exposure head 4 is provided with positioning pins 45F and 45B that serve as positioning shafts. The housing 54 is a conductive member that has conductivity, and the positioning pins 45F and 45B are also conductive members. In this embodiment, the positioning pins 45F and 45B are both made of metal.

[0026] The positioning pins 45F and 45B are fixed to both ends of the housing 54 in the longitudinal direction (FB direction). The positioning pin 45F is fixed to the housing 54 on one side (front side) of the lens array 52 in the longitudinal direction (FB direction), and protrudes from both sides of the housing 54 in the optical axis direction (UD direction) of the lens array 52. ​​The positioning pin 45B is fixed to the housing 54 on the other side (rear side) of the lens array 52 in the longitudinal direction (FB direction), and protrudes from both sides of the housing 54 in the optical axis direction of the lens array 52.

[0027] In order to ensure the distance between the surface of the photosensitive drum 2 and the light emission surface of the lens array 52 of the exposure head 4 with high precision, the position of the positioning surface at the tip of the shaft of the positioning pins 45F, 45B is adjusted using the housing 54 as a reference, and the positioning pins 45F, 45B are caulked to the housing 54. Note that the method of fixing the positioning pins 45F, 45B to the housing 54 is not limited to this; for example, metal positioning pins 45F, 45B may be fixed to the metal housing 54 by welding. In this way, in this embodiment, the positioning pins 45F, 45B are integrated with the housing 54.

[0028] When positioning the exposure head 4 with respect to the photosensitive drum 2, the positioning surfaces at the axial tips of the positioning pins 45F and 45B are abutted against bearings that rotatably support the photosensitive drum 2. As a result, a gap is formed between the lens array 52 of the exposure head 4 and the photosensitive drum 2, as shown in FIGS. 4(a) and 4(b). This determines the distance (gap) between the exposure head 4 and the photosensitive drum 2 in a direction perpendicular to the rotation axis direction of the photosensitive drum 2, and determines the position of the exposure head 4 with respect to the photosensitive drum 2. Then, as shown in FIG. 4(b), light emitted from LEDs 51a (see FIG. 5(c) described later) serving as light-emitting elements is focused by the lens array 52 onto the surface 2a of the photosensitive drum 2, serving as the irradiated surface.

[0029] [Substrate and lens array] Next, the substrate 50 and lens array 52 of the exposure head 4 will be described with reference to Figures 5(a) to (e) and Figure 6. First, the substrate 50 will be described. Figure 5(a) is a schematic perspective view of the substrate 50 as seen from the surface on which the LEDs 51a are mounted (the surface of the substrate). Figure 5(b) shows the arrangement of a plurality of LED chips 53-1 to 53-29 (hereinafter sometimes simply referred to as "LED chips 53") that make up the light-emitting element group (LED array) 51 provided on the substrate 50, and Figure 5(c) is an enlarged view of Figure 5(b). Figure 6 is a plan view schematically showing the back surface of the substrate 50.

[0030] A plurality of LED chips 53 constituting a light-emitting element group 51 are mounted on the substrate 50. As shown in Fig. 5(a), the LED chips 53 are provided on one surface (first surface) of the substrate 50, and a long FFC connector 57 is provided on the other surface (second surface). The one surface of the substrate 50 here refers to the surface (upper surface, front surface) facing the lens array 52. ​​The other surface of the substrate refers to the surface behind the one surface (the surface opposite to the side on which the LED chips 53 are provided, lower surface, back surface).

[0031] The FFC connector 57 is a connector that receives power from the outside (the main body of the image forming apparatus 100) and receives signals when the exposure head 4 is in use, and is attached to the other surface of the substrate 50 so that its longitudinal direction is along the longitudinal direction of the substrate 50. The long FFC connector 57 is provided on the front side of the image forming apparatus 100 (one side in the longitudinal direction of the substrate 50). The substrate 50 is provided with wiring for supplying signals to each LED chip 53. One end of a flexible flat cable (not shown, hereinafter referred to as FFC), which is an example of a cable, is connected to the FFC connector 57.

[0032] 6, in addition to the above-mentioned FFC connector 57, a check pad (electrical contact) 601 and an IC (integrated circuit) 600 are provided on the back surface of the substrate 50. As will be described in detail later, the check pad 601 is an electrical contact that is electrically connected to the plurality of LED chips 53, and is used when positioning the lens array 52 relative to the housing 54 and when checking its operation. In this embodiment, the substrate 50 has the above-mentioned FFC connector 57, in addition to the check pad 601, as a connector to be used when using the exposure head 4.

[0033] The control circuit unit of the image forming apparatus 100 body is provided with a substrate (not shown) equipped with a control unit and a connector. The other end of the FFC is connected to the connector. That is, the FFC electrically connects the substrate (control circuit unit) of the apparatus body to the substrate 50 of the exposure head 4. A control signal (drive signal) is input from the control circuit unit of the image forming apparatus 100 body to the IC 600 of the substrate 50 via the FFC and FFC connector 57. The control signal is transferred to each LED chip 53. The LED chip 53 is driven (to emit light or turn off) by the control signal input to the IC 600. Specifically, the FFC connector 57 is connected to the control circuit unit provided in the apparatus body and receives image data that controls the on / off of each LED chip 53. The image data input to the FFC connector 57 is converted by the IC 600 into a signal suitable for driving each LED chip 53. In this embodiment, image data is input to the FFC connector 57 as serial data, converted into parallel data by the IC 600, and then transmitted to each LED chip 53.

[0034] The LED chips 53 mounted on the substrate 50 will be described in more detail. As shown in FIGS. 5(b) and 5(c), LED chips 53-1 to 53-29 (29 chips), each including a plurality of LEDs 51a (an example of a light-emitting element), are arranged on one surface of the substrate 50. Each of the LED chips 53-1 to 53-29 has 516 LEDs 51a arranged in its longitudinal direction. The center-to-center distance K2 between adjacent LEDs 51a in the longitudinal direction of the LED chip 53 corresponds to the recording resolution of the image forming apparatus 100. Since the recording resolution of the image forming apparatus 100 of this embodiment is 1200 dpi, the LEDs 51a are arranged in the longitudinal direction of the LED chips 53-1 to 53-29 such that the center-to-center distance K2 between adjacent LEDs 51a is 21.16 μm. Therefore, the exposure range of the exposure head 4 of this embodiment is approximately 314 mm. The length of the photosensitive layer in the direction of the rotation axis of the photosensitive drum 2 is 314 mm or more. Since the length of the long side of an A4 size recording material and the length of the short side of an A3 size recording material are 297 mm, the exposure head 4 of this embodiment has an exposure range that allows images to be formed on A4 size recording material and A3 size recording material.

[0035] The LED chips 53-1 to 53-29 are arranged in a staggered pattern in the rotational axis direction (main scanning direction) of the photosensitive drum 2. Specifically, the LED chips 53-1 to 53-29 are alternately arranged in two rows along the rotational axis direction of the photosensitive drum 2. That is, as shown in FIG. 5(b), counting from the left, the odd-numbered LED chips 53-1, 53-3, ... 53-29 (odd-numbered rows) are mounted in a row along the longitudinal direction (main scanning direction) of the substrate 50. Also, counting from the left, the even-numbered LED chips 53-2, 53-4, ... 53-28 (even-numbered rows) are mounted in a row along the longitudinal direction (main scanning direction) of the substrate 50 at positions shifted in the rotational direction (sub-scanning direction) of the photosensitive drum 2 from the odd-numbered rows.

[0036] By arranging multiple LED chips 53 in this manner, as shown in Figure 5(c), the center-to-center distance K1 between LEDs 51a arranged between one end of one LED chip 53 and the other end of the other LED chip 53 in adjacent different LED chips 53 in the longitudinal direction of the LED chips 53 can be made equal to the center-to-center distance K2 between adjacent LEDs 51a on one LED chip 53.

[0037] As described above, the light-emitting elements of this embodiment are semiconductor LEDs, which are light-emitting diodes. In particular, in this embodiment, the LED 51a is an OLED (organic light-emitting diode). This OLED uses an organic material as a light-emitting body and emits light when electricity is passed through the light-emitting body. It is a current-driven light-emitting element also known as organic EL (organic electro-luminescence). The OLEDs are arranged in a line along the main scanning direction (the direction of the rotation axis of the photosensitive drum 2) on a TFT (thin film transistor) substrate, for example, and are electrically connected in parallel by power supply wiring also provided along the main scanning direction. The LED 51a may be an LED using an inorganic material as a light-emitting body.

[0038] Next, the lens array 52, which is a lens assembly, will be described. FIG. 5(d) is a schematic diagram of the lens array 52 as viewed from the photosensitive drum 2 side. FIG. 5(e) is a schematic perspective view of the lens array 52. ​​As shown in FIG. 4(b) above, the lens array 52 focuses light emitted from each LED 51a of the light-emitting element group 51 onto the surface 2a of the photosensitive drum 2. The lens array 52 is a lens assembly having a plurality of lenses 52a. These lenses are arranged in two rows along the arrangement direction of the plurality of LEDs 51a. That is, the lenses are arranged in two rows in the main scanning direction so as to correspond to the above-mentioned two rows of LED chips 53.

[0039] The lenses 52a are arranged alternately in one row such that one lens 52a in one row is in contact with both of the lenses 52a adjacent to it in the arrangement direction of the lenses 52a in the other row. Each lens 52a is a cylindrical glass rod lens and has a light incident surface 52b onto which light emitted from the LED 51a enters and a light exit surface 52c from which the light incident from the light incident surface 52b exits (see FIG. 2). The material of the lenses 52a is not limited to glass and may be plastic. The shape of the lenses 52a is also not limited to cylindrical and may be a polygonal prism such as a hexagonal prism.

[0040] The dotted line Z in Figure 5(e) indicates the optical axis of the lens 52a. Here, the optical axis of the lens 52a refers to the line connecting the center of the light-emitting surface of the lens 52a and the focal point of the lens 52a. The lens array 52 is a lens assembly having multiple lenses 52a, and the aforementioned "optical axis" refers to the optical axis of any one of these lenses 52a. Strictly speaking, the multiple lenses 52a in the lens array 52 may be slightly tilted relative to each other. This is due to assembly tolerances. However, deviations within the tolerance range mentioned here will not be taken into account when defining the direction of the optical axis. Therefore, the optical axes of the multiple lenses 52a are considered to be in the same direction. The lens array 52 serves to focus light emitted from the LED 51a onto the surface 2a of the photosensitive drum 2.

[0041] In addition, when assembling the exposure head 4, the mounting position of the lens array 52 relative to the housing 54 is adjusted so that the distance between the light-emitting surface of the LED 51a and the light-incident surface of the lens 52a and the distance between the light-exiting surface of the lens 52a and the surface 2a of the photosensitive drum 2 are approximately equal.

[0042] [Comparative Example] Here, a comparative example of a manufacturing method of the exposure head 4 will be described with reference to Figs. 7(a) to 10(d). In the comparative example, after the lens array 52 is fixed to the housing 54, the substrate 50 is fixed to the housing 54. As shown in Fig. 7(a), the lens array 52 is prepared, held in the housing 54 by a lens array holding tool 703. Then, as shown in Fig. 7(b), the midpoint L of the optical axis direction of the lens array 52 is measured using a lens array position adjustment camera 800. m However, the position is adjusted so that it coincides with the midpoint of the distance TC between the light-emitting surface E of the multiple LED chips 53 provided on the substrate 50 and the position S corresponding to the surface 2a of the photosensitive drum 2 when the exposure head 4 is mounted on the image forming device 100.

[0043] Thereafter, as shown in Fig. 8(a), an ultraviolet-curing UV adhesive 77 is applied between the lens array 52 and the housing 54. At this time, in the comparative example, the UV adhesive 77 is applied from the outside of the housing 54. Then, as shown in Fig. 8(b), ultraviolet light (UV) is irradiated onto the UV adhesive 77, thereby fixing the lens array 52 to the housing 54 as shown in Fig. 8(c).

[0044] Next, as shown in FIG. 9( a), the substrate 50 is suction-held by a suction pad 602. Then, as shown in FIG. 9( b), while the substrate 50 is held by the suction pad 602, warping of the substrate 50 is corrected and an electrical contact tool 704 is pressed against the substrate 50 to cause the LEDs 51a to emit light when the position of the substrate 50 is adjusted in the next step. While maintaining this state, as shown in FIG. 10( a), light emitted from the multiple LED chips 53 on the substrate 50 toward the lens array 52 is received by a substrate position adjustment camera 801. Then, the position of the substrate 50 on which the multiple LED chips 53 are mounted is adjusted to a position where the imaging characteristics are optimal when the multiple light-emitting points aligned in the longitudinal direction on the substrate 50 form an image on the surface 2a of the photosensitive drum 2 through the lens array 52. Thereafter, as shown in FIG. 10(b), UV adhesive 77 is applied between the substrate 50 and the housing 54, and as shown in FIG. 10(c), ultraviolet light is irradiated onto the UV adhesive 77, thereby fixing the substrate 50 to the housing 54 as shown in FIG. 10(d).

[0045] In the method of the comparative example described above, when the lens array 52 is fixed to the housing 54, the UV adhesive 77 is applied from the outside of the housing 54. Therefore, as shown in Fig. 10(d), the UV adhesive 77 is present around the lens array 52 and on the outside of the housing 54. That is, the UV adhesive 77 is present on the outer surface of the housing 54 on the side where the lens array 52 protrudes (the light exit surface 52c side) and around the lens array 52, so that it protrudes from this outer surface toward the light exit surface 52c of the lens array 52.

[0046] [Lens array cleaning] The lens array 52 emits light from the light exit surface 52c toward the surface 2a of the photosensitive drum 2. However, this light exit surface 52c may become contaminated with toner or other contaminants. Specifically, as shown in FIGS. 4(a) and 4(b), the exposure head 4 is positioned close to the surface 2a of the photosensitive drum 2. Because toner for developing an electrostatic latent image adheres to the surface 2a of the photosensitive drum 2, depending on the amount of toner adhered, the toner may scatter near the surface of the photosensitive drum 2 and adhere to the light exit surface 52c of the lens array 52. ​​If toner adheres to the light exit surface 52c of the lens array 52, the light emitted by the exposure head 4 to form an electrostatic latent image on the surface 2a of the photosensitive drum 2 is blocked by the adhered toner, reducing the amount of light reaching the surface 2a of the photosensitive drum 2. This can result in insufficient exposure, potentially resulting in poor image formation. Therefore, if toner adheres to the light exit surface 52c of the lens array 52, it is desirable to remove the adhered toner.

[0047] 11 is a perspective view of a cleaning rod 901 serving as a cleaning tool used in this embodiment. The cleaning rod 901 holds a cleaning member 903 (FIG. 13) described below, moves along the longitudinal direction of the lens array 52, and has the function of removing foreign matter adhering to the light exit surface 52c of the lens array 52 by rubbing the light exit surface 52c of the lens array 52 with the cleaning member 903. For example, a user or a service person holds a grip portion 902 provided at an end of the cleaning rod 901 in the longitudinal direction and moves the cleaning rod 901 along the longitudinal direction of the lens array 52 to clean the light exit surface (surface) 52c.

[0048] The configuration of the cleaning rod 901 will be described with reference to Figures 12 to 14. Figure 12 is a perspective view of one end of the cleaning rod 901, which is opposite the grip portion 902 in the longitudinal direction, as viewed from the front side. Figure 13 is a perspective view of one end of the cleaning rod 901 as viewed from the back side. For convenience, in this embodiment, the side on which the cleaning member 903, which will be described later, is provided is referred to as the back side, and the opposite side is referred to as the front side. Figure 14 is a perspective view showing the positional relationship between the cleaning rod 901 and the exposure head 4.

[0049] As shown in FIG. 13 , the cleaning rod 901 includes a cleaning member 903 on the back side of one longitudinal end that rubs against the light-emitting surface 52 c of the lens array 52 to clean it. The cleaning member 903 is preferably made of a material that rubs against the light-emitting surface 52 c of the lens array 52 without damaging it, such as elastic rubber, nonwoven fabric, or sponge. As shown in FIGS. 12 and 13 , the cleaning rod 901 also includes a protrusion 906 that protrudes from one side in the width direction (the LR direction described below) perpendicular to the longitudinal direction. The protrusion 906 is located near the cleaning member 903 on one longitudinal end and, as described below, functions to restrict movement of the cleaning member 903, which moves along the longitudinal direction of the exposure head 4, in the optical axis direction (UD direction) of the lens array 52.

[0050] 14, for example, a user or service technician inserts the cleaning rod 901 into a unit (e.g., a drum unit) that includes an exposure head 4 and a photosensitive drum 2 from the outside of the unit along the longitudinal direction (FB direction) of the exposure head 4. A guide member 908 that guides the cleaning rod 901 toward the exposure head 4 is provided inside the device body of the image forming apparatus 100 in which the unit is arranged. The guide member 908 is provided, for example, on the F side of the F-side end of the exposure head 4 in the FB direction, and guides the cleaning rod 901 inserted from the F side of the device body to the exposure head 4.

[0051] 14 , a regulating member 909 is provided along the longitudinal direction of the exposure head 4. The regulating member 909 engages with a protrusion 906 of the cleaning rod 901 inserted via a guide member 908, and has the function of guiding the movement of the cleaning rod 901 along the longitudinal direction of the exposure head 4. When the regulating member 909 and the protrusion 906 are engaged, the movement of the cleaning rod 901 in the optical axis direction of the lens array 52 is restricted. This reduces the risk of the cleaning member 903 and the surface of the lens array 52 becoming separated when the cleaning rod 901 moves along the longitudinal direction of the lens array 52. ​​As a result, the surface of the lens array 52 can be reliably cleaned by the cleaning rod 901.

[0052] As described above, in this embodiment, the light exit surface 52c of the lens array 52 may be cleaned by the cleaning member 903. When performing the cleaning operation, the cleaning rod 901 is moved along the lens array 52 of the exposure head 4 that is exposed to the outside of the housing 54. At this time, if the UV adhesive 77 hardens around the lens array 52 and outside the housing 54, as in the comparative example described above, there is a risk that part of the cleaning rod 901 will interfere with the UV adhesive 77 during cleaning, as shown in FIG. 15 . As a result, there is a risk that the light exit surface 52c of the lens array 52 will not be properly cleaned, or that the UV adhesive 77 will be scraped off during cleaning.

[0053] That is, as shown in FIG. 15, the cleaning rod 901 has an upper plate 901a to which the cleaning member 903 is fixed, and a pair of side plate portions 901b extending from both ends of the upper plate 901a in the width direction (a direction perpendicular to the longitudinal direction of the cleaning rod 901 (the direction indicated by arrows LR in FIG. 2, which are perpendicular to the FB direction in FIG. 3 and the up-down direction in FIG. 2)) toward the housing 54. During cleaning, the cleaning member 903 slides over the light exit surface 52c of the lens array 52 with the upper plate 901a and the pair of side plate portions 901b covering the periphery of the lens array 52. ​​This makes it possible to prevent toner and the like adhering to the lens array 52 from scattering around during cleaning. However, during cleaning, the tips of the pair of side plate portions 901b pass near the outer surface of the housing 54, and if the UV adhesive 77 is present around the lens array 52 and on the outside of the housing 54, as in the comparative example, there is a risk of interference between the pair of side plate portions 901b and the UV adhesive 77, as shown by the diagonal grid in Figure 15.

[0054] [Method for manufacturing exposure apparatus according to this embodiment] Therefore, in this embodiment, the exposure head 4 serving as an exposure device is manufactured by the following method. The manufacturing method for the exposure head 4 of this embodiment will be described using the flowchart in FIG. 16 and FIGS. 17(a) to 19(c). The manufacturing method for the exposure head 4 of this embodiment includes a first step in which, with the lens array 52 positioned in a first opening 54a of a housing 54 (described later), an adhesive is applied between the lens array 52 and the housing 54 from the second opening 54b side to fix the lens array 52 to the housing 54 with the adhesive, and a second step in which, after the first step, the substrate 50 is fixed to the housing 54. That is, in this embodiment, the adhesive for fixing the lens array 52 to the housing 54 is applied to the inside of the housing 54 to fix the lens array 52 to the housing 54, and then the substrate 50 on which multiple LED chips 53 are provided is fixed to the housing 54. The exposure head 4 is manufactured by a manufacturing device using a robot or the like. In this embodiment, the substrate 50 and the lens array 52 are fixed to the housing 54 with the adhesive.

[0055] For convenience, in this specification, with respect to the optical axis direction of the lens array 52, the side from which light is emitted from the lens array 52 (i.e., the side of the light exit surface 52c, the upper side in FIG. 2) is referred to as the upper side, and the side from which light is incident on the lens array 52 (i.e., the side of the light incident surface 52b, the lower side in FIG. 2) is referred to as the lower side. Therefore, the "vertical direction (UD direction)" used in the description of the exposure head 4 in this specification may differ from the actual vertical direction (upward / downward direction) when the exposure head 4 is attached to the image forming apparatus 100. The housing 54 is a metal member formed by bending a plated material such as a galvanized steel plate or a cold-rolled steel plate. In this embodiment, the housing 54 is shown as a thin metal plate formed into a U-shape by pressing.

[0056] The housing 54 has a first opening 54a through which the lens array 52 is inserted, and a second opening 54b formed on the opposite side in a U-shape through which the substrate 50 is inserted. Specifically, the housing 54 has an upper plate 54U as a first portion in which the first opening 54a is formed, and a pair of bent plate portions 54L, 54R as a pair of second portions extending from both ends of the upper plate 54U toward the opposite side of the irradiated surface in a direction perpendicular to the longitudinal direction of the lens array 52 (the arrow LR direction in FIG. 2, which is perpendicular to the FB direction in FIG. 3 and the up-down direction in FIG. 2). The second opening 54b is a space between the pair of bent plate portions 54L, 54R and has a larger opening area than the first opening 54a. The lens array 52 is fixed to the housing 54 while passing through the first opening 54a, and the substrate 50 is fixed between the pair of bent plate portions 54L, 54R.

[0057] First, as shown in FIG. 17(a), a lens array 52 held by a lens array holding tool 703 is prepared (S1 in FIG. 16), and the position of the lens array 52 is adjusted in six axes using a lens array position adjustment camera 800 (S2 in FIG. 16). The six-axis adjustment includes adjustment in each of the mutually orthogonal X-, Y-, and Z-axes, as well as adjustment in the roll (yaw, pitch, roll) directions for each axis. The housing 54 shown in FIG. 17(a) is inverted in the up-down direction (UD direction) from when the exposure head 4 is mounted on the image forming apparatus 100, and is held by a jig (not shown). The position adjustment of the lens array 52 is the same as in the comparative example, and the midpoint L in the optical axis direction of the lens array 52 is adjusted. m However, the position of the lens array 52 relative to the housing 54 is adjusted so that it coincides with the midpoint of the distance TC between the light-emitting surface E of the multiple LED chips 53 provided on the substrate 50 and the position S corresponding to the surface 2a of the photosensitive drum 2 when the exposure head 4 is mounted on the image forming device 100.

[0058] In this embodiment, the lens array 52 is positioned relative to the housing 54 via a gap 76. With the position of the lens array 52 adjusted in this manner maintained, as shown in FIG. 17(b), a plurality of UV adhesive application needles 706 apply an ultraviolet-curing UV adhesive (first adhesive) 77 between the lens array 52 and the housing 54 (S3 in FIG. 16). At this time, in this embodiment, the UV adhesive 77 is applied from the second opening 54b side (i.e., from the inside of the housing 54). In this embodiment, with the lens array 52 positioned relative to the housing 54 via the gap 76, the UV adhesive 77 is applied between the lens array 52 and the housing 54.

[0059] Next, as shown in FIG. 17(c), ultraviolet light is irradiated onto the UV adhesive 77 from a UV light 707 to harden the adhesive (S4 in FIG. 16). As a result, as shown in FIG. 17(d), the lens array 52 is fixed to the housing 54 by the UV adhesive 77 (S5 in FIG. 16). That is, in this embodiment, in the first step, with the lens array 52 positioned in the first opening 54a, the UV adhesive 77, which is an ultraviolet-curing adhesive, is applied between the lens array 52 and the housing 54 from the side of the second opening 54b. Thereafter, ultraviolet light is irradiated onto the UV adhesive 77 from the side of the second opening 54b. As a result, the lens array 52 is fixed to the housing 54.

[0060] As described above, in the exposure head 4 of the present embodiment, the UV adhesive 77 is applied to the inside of the housing 54 on the second opening 54b side, between the lens array 52 and the housing 54, and fixes the lens array to the housing 54. Therefore, in the present embodiment, unlike the comparative example, the UV adhesive 77 is present around the lens array 52, rising from the inner surface of the upper plate portion 54U of the housing 54 toward the inside of the housing 54 (the second opening 54b side), and almost no UV adhesive 77 is present outside the upper plate portion 54U (the light exit surface 52c side of the lens array 52).

[0061] Next, as shown in FIG. 18(a), the substrate 50 on which the multiple LED chips 53 are mounted is sucked at multiple locations along its longitudinal direction by suction pads 602, and then, as shown in FIG. 18(b), any warping or bending of the substrate 50 is corrected (S6 in FIG. 16).

[0062] 19(a), the substrate 50 is inserted through the second opening 54b, and the electrical contact tool 704 is pressed against the check pad 601 (FIG. 6) of the substrate 50, thereby preparing the substrate 50 so that the multiple LED chips 53 provided on the substrate 50 can emit light (S7 in FIG. 16). As a result, the contact probe 704a provided at the tip of the electrical contact tool 704 is pressed against the check pad 601, enabling electrical continuity with the multiple LED chips 53. The check pad 601 is an electrical contact that the contact probe 704a comes into contact with when the exposure head 4 is assembled, and supplies power to the multiple LED chips 53 to light up the multiple LEDs 51a.

[0063] 6, in this embodiment, the check pad 601 is disposed in a position that does not overlap the area of ​​the substrate 50 in which the LED chip 53 is provided, in the front-to-back direction of the substrate 50. In other words, the check pad 601 is disposed outside the area of ​​the substrate 50 in which the LED chip 53 is mounted, in the longitudinal direction of the substrate 50. This prevents the pressing force of the contact probe 704a from being directly applied to the area in which the LED chip 53 is mounted, thereby reducing the impact on the LED chip 53 of bending of the substrate 50 due to the pressing force of the contact probe 704a. The electrical contact tool 704 includes wiring that supplies a control signal that controls the light emission of the LED chip 53, and wiring that supplies power that controls the light emission of the LED chip 53.

[0064] As shown in Fig. 19(a), the LED chips 53 on the substrate 50 are caused to emit light by a signal input from the electrical contact tool 704 (S8 in Fig. 16), and the substrate position adjustment camera 700 is used to adjust the substrate 50 along six axes to a position where the imaging characteristics and light quantity efficiency are the best (S9 in Fig. 16). In this embodiment, the substrate 50 is positioned relative to the housing 54 via a gap 76. The housing 54 shown in Fig. 19(a) is inverted in the up-down direction (UD direction) from when the exposure head 4 is mounted on the image forming apparatus 100, and is held by a jig (not shown).

[0065] While maintaining the position of the substrate 50 adjusted as described above, as shown in Fig. 19(b), an ultraviolet-curing UV adhesive 77 is applied between the substrate 50 and the housing 54 from the second opening 54b side using a plurality of UV adhesive application needles 701 (S10 in Fig. 16). In this embodiment, the UV adhesive 77 is applied between the substrate 50 and the housing 54 with the substrate 50 positioned relative to the housing 54 via a gap 76.

[0066] Next, as shown in FIG. 19(c), ultraviolet light is irradiated onto the UV adhesive 77 from the UV light 702 to harden the adhesive (S11 in FIG. 16). As a result, as shown in FIG. 19(d), the substrate 50 is fixed to the housing 54 by the UV adhesive 77 (S12 in FIG. 16). That is, in this embodiment, in the second step, the substrate 50 is inserted into the housing 54 through the second opening 54b, and with the substrate 50 positioned relative to the housing 54, the UV adhesive 77, which is an ultraviolet-curing adhesive, is applied between the substrate 50 and the housing 54 from the side of the second opening 54b. Thereafter, ultraviolet light is irradiated onto the UV adhesive 77 from the side of the second opening 54b. As a result, the substrate 50 is fixed to the housing 54.

[0067] Furthermore, in this embodiment, after the second step, a thermosetting adhesive 78 (hereinafter also referred to as "thermosetting adhesive 78", see FIG. 20 described later) is applied between the substrate 50 and the housing 54 (S13 in FIG. 16). Then, the entire exposure head 4 including the substrate 50 and the housing 54 is heated to heat the thermosetting adhesive 78 (S14 in FIG. 16). As a result, the substrate 50 is fixed to the housing 54 by the thermosetting adhesive 78. That is, in this embodiment, the substrate 50 is fixed to the housing 54 by the UV adhesive 77 and the thermosetting adhesive 78.

[0068] As described above, the substrate 50 is fixed to the housing 54 using two types of adhesive. The LED chips 53 provided on the substrate 50 tend to generate heat over time, which can cause the temperature of the entire exposure head 4, including the substrate 50 and housing 54, to rise. Since the substrate 50 and the housing 54 are made of different materials, they have different linear expansion coefficients, which results in a difference in the rate of expansion when the temperature rises. Therefore, if the substrate 50 and the housing 54 are heated significantly, the difference in the thermal expansion coefficients may cause the bonded substrate 50 and housing 54 to peel off. Therefore, it is desirable that the substrate 50 and the housing 54 be firmly bonded together.

[0069] Therefore, in this embodiment, the substrate 50 and the housing 54 are bonded together using a thermosetting adhesive (hereinafter referred to as a thermosetting adhesive) 78 in addition to the UV adhesive 77, as shown in FIG. 20 . FIG. 20 is a perspective view showing the bonding configuration between the substrate 50 and the housing 54. The thermosetting adhesive 78 is an adhesive that hardens when heat is applied after application. Generally, the thermosetting adhesive 78 has excellent hardness after hardening, but often requires a long time to harden. If it takes a long time to bond the substrate 50 and the housing 54 together, the position of the substrate 50 relative to the housing 54 may deviate from the design value, and the light source may deviate from the focal position of the lens array 52, resulting in a deterioration in the optical performance of the exposure head 4. For this reason, in this embodiment, the substrate 50 and the housing 54 are bonded together using a UV adhesive 77, which has properties different from the thermosetting adhesive, in addition to the thermosetting adhesive 78.

[0070] As described above, the UV adhesive 77 is an adhesive that has the property of being cured by irradiation with UV light after application. The UV adhesive 77 begins to harden upon irradiation with UV light, and therefore has a faster hardening speed than the thermosetting adhesive 78. Meanwhile, as described above, it is desirable to achieve strong adhesion between the substrate 50 and the housing 54, but while the UV adhesive 77 has an excellent hardening speed, there is a risk that the hardness of the adhesive after hardening may be insufficient when bonding the substrate 50 and the housing 54 together.

[0071] For this reason, in the method of manufacturing the exposure head 4 in this embodiment, the substrate 50 and the housing 54 are bonded together in the following procedure. First, with the position of the substrate 50 relative to the housing 54 defined, the housing 54 and the substrate 50 are fixed together with a UV adhesive 77 (S10 to S12 in FIG. 16). Then, after the UV adhesive 77 has hardened, a thermosetting adhesive 78 is applied between the substrate 50 and the housing 54 (S13 in FIG. 16). Thereafter, heat is applied to the entire exposure head 4 to harden the thermosetting adhesive (S14 in FIG. 16). The UV adhesive 77 is hard enough to hold the substrate 50 against the housing 54, and the risk of the substrate 50 becoming misaligned relative to the housing 54 while the thermosetting adhesive 78 is hardening can be reduced.

[0072] As described above, in this embodiment, a plurality of adhesives having different hardening speeds and hardnesses are used to bond the substrate 50 to the housing 54. As a result, even if an adhesive with excellent hardness (thermosetting adhesive 78 in this embodiment) takes time to harden, the adhesive with excellent hardening speed (UV adhesive 77 in this embodiment) can adhere the substrate 50 without misalignment relative to the housing 54. As a result, it is possible to firmly fix the substrate 50 to the housing 54 while ensuring the position of the substrate 50 relative to the housing 54 with high precision.

[0073] According to this embodiment, even if the lens array 52 is fixed to the housing 54 with an adhesive, interference between the cleaning rod 901 used to clean the lens array 52 and the adhesive can be suppressed. That is, as shown in FIG. 21 , the UV adhesive 77 used to fix the lens array 52 to the housing 54 is present around the lens array 52 and inside the housing 54. Specifically, the UV adhesive 77 is present around the lens array 52 so as to rise from the inner surface of the upper plate portion 54U of the housing 54 toward the inside of the housing 54 (toward the second opening 54b). Therefore, even if the tips of the pair of side plate portions 901b of the cleaning rod 901 pass near the outer surface of the housing 54 when cleaning the lens array 52, the pair of side plate portions 901b do not interfere with the UV adhesive 77. As a result, poor cleaning of the light exit surface 52c of the lens array 52 can be suppressed, and scraping of the UV adhesive 77 during cleaning can be suppressed.

[0074] As described above, in this embodiment, almost no UV adhesive 77 is present on the outside of the upper plate 54U of the housing 54 (on the light exit surface 52c side of the lens array 52), but even if UV adhesive 77 is present on the outside of the upper plate 54U, it is only a portion of the UV adhesive 77 that protrudes to the outside through the gap 76, as shown in Fig. 21. Therefore, even if the tips of the pair of side plate portions 901b of the cleaning rod 901 touch the vicinity of the outer surface of the upper plate 54U during cleaning, they are unlikely to interfere with the UV adhesive 77 that protrudes slightly to the outside.

[0075] [Other embodiments] Unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components shown in the above-described embodiments are not intended to limit the scope of the present invention, and any configuration that can achieve similar effects may be used. For example, although a UV adhesive that can be hardened in a short time was used as the adhesive, other materials may be used, and although a check pad was used for electrical connection with the board, other cable connectors may be used.

[0076] Furthermore, in the above-described embodiment, the substrate 50 and the lens array 52 are positioned relative to the housing 54 via the gap 76, but at least one of the substrate 50 and the lens array 52 may be positioned by contacting a part of the housing. Furthermore, in the above-described embodiment, the housing 54 is formed by bending a metal sheet, but the housing may be made of metal with a machined abutment surface against which the substrate 50 or the lens array 52 abuts, or may be made of resin with a molded abutment surface. [Explanation of symbols]

[0077] 2. Photosensitive drum (photoconductor) 2a...Surface (irradiated surface) 4. Exposure head (exposure device) 50... board 51... Light-emitting element group 51a LED (light emitting element) 52 Lens array 53 LED chip 53 54 Housing (holding member) 54a...1st opening 54b...Second opening 54U···Upper plate (first part) 54L, 54R... Bent plate section (second section) 77···UV adhesive 78...Heat-curing adhesive 100 Image forming device

Claims

1. A method for manufacturing an exposure device including: a substrate; a plurality of light-emitting elements provided on the substrate; a lens array that focuses light emitted from the plurality of light-emitting elements onto an irradiated surface; and a holding member in which a first opening and a second opening having an opening area larger than that of the first opening are formed, the holding member holding the lens array in a state where it passes through the first opening, and holding the substrate at a position closer to the second opening than the lens array, a first step of applying an adhesive between the lens array and the holding member from the second opening side while the lens array is positioned in the first opening, and fixing the lens array to the holding member with the adhesive; a second step of fixing the substrate to the holding member after the first step.

2. 2. A method for manufacturing an exposure apparatus according to claim 1, wherein in the second step, the substrate is inserted into the holding member through the second opening, and while the substrate is positioned inside the holding member, adhesive is applied between the substrate and the holding member from the side of the second opening, and the substrate is fixed to the holding member by the adhesive.

3. The adhesive is an ultraviolet curing adhesive, 2. The method for manufacturing an exposure device according to claim 1, wherein in the first step, with the lens array positioned in the first opening, the ultraviolet-curing adhesive is applied between the lens array and the holding member from the second opening side, and then ultraviolet light is irradiated onto the ultraviolet-curing adhesive from the second opening side.

4. The adhesive is an ultraviolet curing adhesive, 3. The method for manufacturing an exposure apparatus according to claim 2, wherein in the second step, with the substrate positioned inside the holding member, the ultraviolet-curing adhesive is applied between the substrate and the holding member from the second opening side, and then ultraviolet light is irradiated onto the ultraviolet-curing adhesive from the second opening side.

5. 5. The method for manufacturing an exposure apparatus according to claim 4, further comprising the steps of: applying a thermosetting adhesive between the substrate and the holding member after the second step; and heating the thermosetting adhesive.

6. the holding member has a first portion in which the first opening is formed, and a pair of second portions extending from both end portions of the first portion to opposite sides of the illuminated surface in a direction perpendicular to the longitudinal direction of the lens array, the second opening is a space between the pair of second portions, 2. The method for manufacturing an exposure apparatus according to claim 1, wherein the substrate is fixed between the pair of second portions.

7. 2. The method for manufacturing an exposure apparatus according to claim 1, wherein the light emitting element is an OLED.

8. A substrate; a plurality of light-emitting elements provided on a substrate; a lens array that focuses the light emitted from the plurality of light-emitting elements onto an illuminated surface; a holding member having a first opening and a second opening having an opening area larger than that of the first opening, the holding member holding the lens array in a state where the holding member penetrates the first opening, and holding the substrate at a position closer to the second opening than the lens array; an adhesive applied to the inside of the holding member on the second opening side between the lens array and the holding member, and fixing the lens array to the holding member.

9. 9. An exposure apparatus according to claim 8, wherein the adhesive is an ultraviolet curing adhesive.

10. the adhesive is a first adhesive; 9. An exposure apparatus according to claim 8, further comprising a second adhesive applied between the substrate and the holding member to fix the substrate to the holding member.

11. 11. An exposure apparatus according to claim 10, wherein the second adhesive is an ultraviolet curing adhesive.

12. In addition to the second adhesive, a third adhesive is applied between the substrate and the holding member to fix the substrate to the holding member; 12. An exposure apparatus according to claim 11, wherein the third adhesive is a thermosetting adhesive.

13. the holding member has a first portion in which the first opening is formed, and a pair of second portions extending from both end portions of the first portion to opposite sides of the illuminated surface in a direction perpendicular to the longitudinal direction of the lens array, the second opening is a space between the pair of second portions, 9. The exposure apparatus according to claim 8, wherein the substrate is fixed between the pair of second portions.

14. 9. An exposure apparatus according to claim 8, wherein the light emitting element is an OLED.

Images