Exposure head and image forming apparatus

Abstract

To accurately position and fix a base plate to a holding body.SOLUTION: An exposure head comprises: a substrate in which a plurality of light emission elements that emit light for exposing a photoreceptor are mounted along the longitudinal direction being the rotation axial direction of the photoreceptor; a lens which condenses the light emitted from the light emission elements on the photoreceptor; and a holding body which holds the substrate and the lens. The holding body has a plurality of contact parts which are brought into contact with a mounting surface on which the light emission elements of the substrate are mounted and determine the position in the optical axis direction of the substrate in the holding body. The plurality of contact parts is provided in the longitudinal direction of the holding body and provided on both sides in the short side direction orthogonal to the longitudinal direction of the holding body.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an exposure head that exposes a photosensitive member and an image forming apparatus equipped with the same. [Background technology]

[0002] Some image forming devices, such as printers and copiers, have an exposure head equipped with multiple light-emitting elements for exposing a photosensitive drum. Some exposure heads use light-emitting diodes (LEDs) as the light-emitting elements. Known exposure heads include those in which the light-emitting elements are arranged in a single row along the rotational axis of the photosensitive drum, or in two staggered rows. The exposure head also includes a lens array for focusing light emitted from the multiple light-emitting elements onto the photosensitive drum. The lens array is disposed between the multiple light-emitting elements and the photosensitive drum, facing the surface of the photosensitive drum along the direction in which the light-emitting elements are arranged. The light emitted from the multiple light-emitting elements is focused onto the surface of the photosensitive drum via the lens array. This forms an electrostatic latent image on the photosensitive drum.

[0003] To obtain a good image in an image forming apparatus, it is necessary to position the exposure head so that the distance from the lens array to the surface of the photosensitive drum and the distance from the light-emitting element to the lens array are equal in the cross section of the exposure head. The light-emitting element is mounted on a substrate, and the substrate has a height difference (waviness) component in the longitudinal direction due to factors such as the thermal load applied when mounting electronic components. For this reason, it is important to fix the substrate to the holder so that the height difference (waviness) component in the longitudinal direction of the substrate is small.

[0004] Patent document 1 describes a configuration in which the surface of the substrate on which the light-emitting element is mounted is pressed against the end face of a substrate fixing portion provided over the entire longitudinal length of the holder, and the substrate and holder are adhesively fixed together. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5333644 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when molding and manufacturing a long-shaped holder, it is difficult to achieve surface precision, such as flatness and parallelism, on the end face of the substrate fixing portion across the entire longitudinal length, resulting in height variations (wavy components) along the longitudinal direction. Therefore, the substrate is adhesively fixed in a position that corresponds to the height variations along the longitudinal length of the end face of the substrate fixing portion of the holder. As a result, the surface on which the light-emitting elements of the substrate are mounted has height variations corresponding to the aforementioned substrate fixing portion of the holder, which may result in variations in the distance from the light-emitting elements mounted on the substrate to the lens array. As a result, the position of the imaging point on the photosensitive drum surface may vary, potentially leading to deterioration in image quality.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to accurately position and fix a substrate to a holder. [Means for solving the problem]

[0008] A typical configuration of the present invention includes a substrate on which a plurality of light-emitting elements that emit light for exposing a photosensitive member are mounted along a longitudinal direction that is the rotational axis direction of the photosensitive member, a lens that focuses the light emitted from the light-emitting elements onto the photosensitive member, and a holder that holds the substrate and the lens, and the holder has a mounting surface on which the light-emitting elements of the substrate are mounted. to a plurality of contact portions that contact the substrate and determine the position of the substrate on the holder in the optical axis direction; Multiple Contact part teeth, Both sides of the holder in the short direction perpendicular to the longitudinal direction In each of the above, a plurality of the holders are arranged in a line along the longitudinal direction of the holder. , the holder further includes a plurality of backup portions configured to abut against a jig supporting the holder, at positions facing the plurality of abutment portions in an optical axis direction perpendicular to the longitudinal direction and the lateral direction, respectively. It is characterized by: [Effects of the Invention]

[0009] According to the present invention, the substrate can be positioned and fixed to the holder with high precision. [Brief explanation of the drawings]

[0010] [Figure 1] An external perspective view of an image forming apparatus [Figure 2] 1 is a cross-sectional view showing a configuration of an image forming apparatus; [Figure 3] A perspective view showing an optical print head [Figure 4] (a) (b) (c) are diagrams showing the configuration of a substrate in an optical print head; (d) (e) are diagrams showing the configuration of a lens array in an optical print head. [Figure 5] 1A and 1B are perspective views showing a holder in an optical print head according to an embodiment of the present invention; [Figure 6] 1 is a cross-sectional view of an optical print head according to an embodiment; [Figure 7] 1 is a cross-sectional view of an optical print head showing the positional relationship of parts around a holder according to an embodiment; [Figure 8] 1 is an explanatory diagram of an optical print head according to an embodiment; [Figure 9] (a) and (b) are cross-sectional views showing the shape of a holder according to another embodiment. [Figure 10] FIG. 10 is an explanatory diagram of an optical print head according to another embodiment; [Figure 11] (a) and (b) are cross-sectional views of the holder during molding according to the embodiment. [Figure 12] 1A and 1B are cross-sectional views showing a substrate fixing step according to an embodiment of the present invention. [Figure 13] 1A and 1B are cross-sectional views showing a substrate fixing step according to an embodiment of the present invention. [Figure 14] (a)(b) is a diagram showing a substrate fixing process of Comparative Example 1. [Figure 15] FIG. 10 is a diagram showing a substrate fixing process of Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0011] Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. However, the components described in this description are merely examples, and the present invention is not limited to the embodiments described in this description.

[0012] Example 1 [External view of image forming device] FIG. 1 is a perspective view showing the entire electrophotographic image forming apparatus 1 of this embodiment. The image forming apparatus 1 shown in FIG. 1 is a multi-function printer (MFP) equipped with a reading device that reads documents. An openable front cover 6 is provided on the front side (predetermined side) of the main body of the image forming apparatus 1. The front cover 6, which is a first door, is a cover for opening the front side of the image forming apparatus 1 when a cartridge or the like is pulled out of the image forming apparatus 1. When a user or an operator such as a service technician performs maintenance work such as cartridge replacement, the operator opens the front cover 6 to perform the work.

[0013] Note that the bidirectional arrows shown in FIG. 1, "front," "rear," "up," "down," "right," and "left," indicate directions in the image forming apparatus 1 shown in FIG. 1 that will be used in the following explanation. "Front" refers to the side of the image forming apparatus 1 to which the front cover 6 is attached, and is sometimes referred to as the front. "Rear" refers to the rear side of the image forming apparatus 1 opposite the front cover 6, and is sometimes referred to as the rear. Also, "up" refers to the top side of the image forming apparatus 1, and "down" refers to the bottom side of the image forming apparatus 1. Furthermore, "right" refers to the right side when the image forming apparatus 1 is viewed from the front cover 6 side, and "left" refers to the left side when the image forming apparatus 1 is viewed from the front cover 6 side.

[0014] [Configuration of image forming device] Next, a schematic configuration of the image forming apparatus 1 will be described. FIG. 2 is a schematic cross-sectional view showing the configuration of the image forming apparatus 1 shown in FIG. 1, showing the configuration when the image forming apparatus 1 is viewed from the front cover 6 side. Note that the image forming apparatus 1 to which this embodiment is applied is a multifunction peripheral equipped with a reading device, but it may also be a printer without a reading device. Furthermore, the image forming apparatus 1 is not limited to a so-called tandem type color image forming apparatus equipped with a plurality of photosensitive drums, which are photosensitive bodies, as shown in FIG. 2, but may also be an image forming apparatus equipped with a single photosensitive drum and forming a monochrome image.

[0015] As shown in FIG. 2, the image forming apparatus 1 includes four image forming units 102Y, 102M, 102C, and 102K (multiple image forming units) that form toner images of yellow (Y), magenta (M), cyan (C), and black (K). Each of the image forming units 102Y, 102M, 102C, and 102K has the same configuration. Therefore, hereinafter, the suffixes Y, M, C, and K indicating the toner colors will be omitted except when referring to a specific image forming unit or a component constituting a specific image forming unit. Note that the image forming units 102 may also be referred to as stations. Each image forming unit 102 includes a photosensitive drum 103 and a charger 104 that charges the photosensitive drum 103. Each image forming unit 102 also includes an exposure unit 500 that uses an LED (light-emitting diode) as a light-emitting element (exposure light source) to emit light that exposes the photosensitive drum 103. 2, the exposure unit 500 is an exposure unit of a so-called "bottom exposure type" that exposes the photosensitive drum 103 from below. By exposure by the exposure unit 500, an electrostatic latent image (latent image) is formed on the photosensitive drum 103 (on the photosensitive member). In addition, the image forming unit 102 is equipped with a developing device 106 that is a developing means that develops the electrostatic latent image formed on the photosensitive drum 103 by attaching toner to the electrostatic latent image, thereby forming a toner image of each color on the photosensitive drum 103.

[0016] The image forming apparatus 1 includes an intermediate transfer belt 107 onto which the toner images formed on the photosensitive drums 103 are transferred, and primary transfer rollers 108 that are disposed opposite the photosensitive drums 103 and transfer the toner images formed on the photosensitive drums 103 onto the intermediate transfer belt 107. The image forming apparatus 1 also includes a secondary transfer roller 109 (transfer means) that transfers the toner images on the intermediate transfer belt 107 onto a recording material S conveyed from a paper feed unit 101, and a fixing device 100 that fixes the unfixed toner images transferred onto the recording material S onto the recording material S.

[0017] The toner remaining on the surface of the photosensitive drum 103 after being transferred to the intermediate transfer belt 107 is removed by a drum cleaning device 8, and the removed toner is accumulated in a recovered toner container 5. In addition, the toner remaining on the surface of the intermediate transfer belt 107 after being transferred to the recording material S is removed by a belt cleaning device 7, and the removed toner is accumulated in a recovered toner container 5.

[0018] [Image formation process overview] Next, an image formation process in the image forming apparatus 1 will be described. When an image is formed in the image forming apparatus 1, first, the surface of the photosensitive drum 103 is charged to a uniform potential by the charger 104. Then, the exposure unit 500 exposes the surface of the photosensitive drum 103 according to image data, thereby forming an electrostatic latent image on the photosensitive drum 103. Then, a toner image is formed by the developer 106 attaching toner to the electrostatic latent image on the photosensitive drum 103. The toner images formed on the photosensitive drum 103 of each image forming unit 102 are sequentially transferred onto the intermediate transfer belt 107 in a superimposed manner by the primary transfer roller 108, forming a color toner image.

[0019] The recording material S is stacked in a paper feed unit 101 and fed to a conveying path 20 in accordance with the image formation timing. The method of feeding the recording material S is as follows: first, the leading edge of the recording material S is flipped up by a paper feed roller 80, and one sheet of recording material S is conveyed to the conveying path 20 by a paper separation conveying roller pair 9, which prevents double feeding of the recording material S. Thereafter, the recording material S is pulled out by a conveying roller pair 10, passes through the conveying path 20, and is conveyed to a registration roller pair (hereinafter referred to as a registration roller pair) 11, where it is temporarily stopped. Then, the registration roller pair 11 performs skew correction and timing correction on the recording material S, and then the recording material S is conveyed to a secondary transfer unit T2.

[0020] The color toner images superimposed and transferred onto the intermediate transfer belt 107 are transported to a secondary transfer section T2 where the recording material S is sandwiched between the intermediate transfer belt 107 and a secondary transfer roller 109. A transfer voltage is applied to the secondary transfer roller 109, so that the toner image on the intermediate transfer belt 107 is transferred onto the recording material S transported from the paper feed section 101. The recording material S onto which the toner image has been transferred at the secondary transfer section T2 is transported to a fixing device 100, which fixes the toner image to the recording material S by heating and pressurizing the unfixed toner image on the recording material S. Then, the recording material S, on which the toner image has been fixed by the fixing device 100, is discharged to a discharge section 111.

[0021] 2, the image forming apparatus 1 is also provided with a toner container 4 provided corresponding to each image forming section 102. When the amount of toner in a developing unit 641, which will be described later, decreases as a result of image formation, the toner is supplied to each developing unit 641 from the toner container 4 corresponding to each image forming section 102 via a pipe (not shown). That is, in the developing unit 641 provided in the image forming apparatus 1 of this embodiment, new toner is replenished from the toner container 4, and part of the excess toner is transported to the recovered toner container 5 as residual toner.

[0022] [Drum unit and developing unit] A replaceable drum unit 518 is attached to each image forming section 102 of the image forming apparatus 1 shown in Fig. 2. The drum unit 518 includes a photosensitive drum 103 rotatably supported on a frame of the drum unit 518. The drum unit 518 is a cartridge that is replaceable by a user or an operator such as a service technician.

[0023] Each image forming section 102 of the image forming apparatus 1 is equipped with a developing unit 641, which is a replaceable unit separate from the drum unit 518. The developing unit 641 is a cartridge in which the developing device 106 shown in FIG. 2 and a toner storage section are integrated. The developing device 106 includes a developing sleeve, which is a developer carrier that carries toner (developer). The developing unit 641 is provided with multiple gears for rotating a screw that mixes the toner and carrier. When these gears deteriorate over time, a service technician removes the developing unit 641 from the main body of the image forming apparatus 1 and replaces it. A certain amount of toner is removed from the developing unit 641 as residual toner, and the removed toner is transported to the recovered toner container 5. The above-described drum unit 518 and developing unit 641 may be a process cartridge in which the drum unit 518 and developing unit 641 are integrated.

[0024] [Optical print head configuration] Next, the optical print head 105 as an exposure head provided in the exposure unit 500 will be described with reference to FIGS. 3 and 4. FIG. 3 is a diagram showing the optical print head 105. FIG. 4 is a diagram showing a schematic configuration of the optical print head 105 provided in the image forming apparatus 1 of this embodiment. Among the exposure methods used in electrophotographic image forming apparatuses is a laser beam scanning exposure method in which a beam of light emitted from a semiconductor laser is deflected by a rotary polygon mirror or the like and irradiated onto a photosensitive drum via an f-θ lens or the like for exposure. The "optical print head 105" described in this embodiment uses an LED exposure method in which the photosensitive drum 103 is exposed using light-emitting elements such as LEDs arranged along the rotational axis of the photosensitive drum 103, and this exposure method is different from the laser beam scanning exposure method described above.

[0025] As described above, the exposure unit 500 of this embodiment exposes the photosensitive drum 103 from below. Therefore, the optical print head 105 is located vertically below the rotation axis of the photosensitive drum 103, and the LEDs 503 of the optical print head 105 expose the surface of the photosensitive drum 103 from below. As shown in FIG. 3 , the optical print head 105 includes a lens array 506, a lens mounting portion 701 to which the lens array 506 is attached, and a holder 505 that holds a substrate 502 (see FIG. 4( c)) on which the LEDs 503 are mounted. The lens mounting portion 701 has an insertion opening (opening) for inserting the lens array 506. In this embodiment, the holder 505 is made of resin such as glass epoxy. The substrate 502 is provided with an FFC connector 504.

[0026] [substrate] Next, the long substrate 502 held by the holder 505 will be described. The direction of the long side of the substrate 502 is the longitudinal direction, and the direction perpendicular to the longitudinal direction is the short direction (or width direction). The longitudinal direction of the substrate 502 is the direction of the rotation axis of the photosensitive drum. FIG. 4(a) is a schematic perspective view showing the shape of the substrate 502. FIG. 4(b) shows the arrangement of multiple LED chips 639 provided on the substrate 502. FIG. 4(c) is an enlarged view of FIG. 4(b). The substrate 502 is mounted with multiple LEDs 503, which are light-emitting elements that emit light to expose the photosensitive drum. Specifically, the substrate 502 is mounted with an LED chip 639 having multiple LEDs 503. As shown in FIG. 4(a), the LED chips 639 are mounted on one surface (hereinafter referred to as the mounting surface) 803 of the substrate 502, and the long FFC connector 504 is provided on the other surface (the surface opposite to the side on which the LEDs 503 are arranged). The FFC connector 504 is attached to the lower surface of the substrate 502 so that its longitudinal direction is aligned with the longitudinal direction of the substrate 502. The substrate 502 is provided with wiring for supplying signals from the FFC connector 504 to each LED chip 639. Furthermore, one end of an FFC (not shown) as an example of a cable is connected to the FFC connector 504.

[0027] The main body of the image forming apparatus 1 is provided with a board having a controller that controls the image forming apparatus 1 and a connector. The other end of the FFC is connected to a connector provided on the board of the controller, and the FFC electrically connects the controller and the board 502. A control signal (drive signal) output from the controller of the main body of the image forming apparatus 1 is input to the board 502 via the FFC and FFC connector 504. An LED chip 639 mounted on the board 502 is driven by the input control signal.

[0028] [LED chip] The LED chips 639 mounted on the substrate 502 will be described in more detail. As shown in FIGS. 4(b) and 4(c), the mounting surface 803 of the substrate 502 has a plurality of LED chips, for example, 29 LED chips 639-1 to 639-29, arranged in order in the longitudinal direction. Each LED chip 639 has a plurality of LEDs 503, which are light-emitting elements. For example, 516 LEDs 503 are arranged in a row in the longitudinal direction inside each LED chip 639. The center-to-center distance k2 between adjacent LEDs 503 in the longitudinal direction inside the LED chip 639 corresponds to the resolution of the image forming apparatus 1. The resolution of the image forming apparatus 1 in this embodiment is, for example, 1200 dpi, and the LEDs 503 are arranged such that the center-to-center distance k2 between adjacent LEDs 503 in the longitudinal direction inside each LED chip 639 is 21.16 μm. As a result, the exposure range of the optical print head 105 in this embodiment is approximately 316 mm (≈21.16 μm × 516 × 29). Meanwhile, the photosensitive layer on the surface of the photosensitive drum 103 exposed by the optical print head 105 is formed with a width of 316 mm or more. Since the length of the long side of A4 size recording paper and the length of the short side of A3 size recording paper are 297 mm, the optical print head 105 in this embodiment has an exposure range that allows images to be formed on both A4 size recording paper and A3 size recording paper.

[0029] The LED chips 639-1 to 639-29 are alternately arranged in two rows along the rotational axis direction of the photosensitive drum 103. That is, as shown in FIG. 4(b), the odd-numbered LED chips 639-1, 639-3, ... 639-29 counting from the left side in the drawing are mounted in a row in the longitudinal direction of the substrate 502. In addition, the even-numbered LED chips 639-2, 639-4, ... 639-28 counting from the left side in the drawing are also mounted in a row in the longitudinal direction. That is, the odd-numbered LED chips 639-1, 639-3, ... 639-29 and the even-numbered LED chips 639-2, 639-4, ... 639-28 are arranged at predetermined intervals (arranged in a staggered pattern) in the short-side direction. By arranging them in this manner, it is possible to make the center-to-center distance k1 between the LEDs 503 arranged at the ends of adjacent LED chips 639 in the longitudinal direction of the LED chip 639 equal to the center-to-center distance k2 between adjacent LEDs 503 within the LED chip 639. Note that although this embodiment shows a configuration in which LEDs 503 are used as the light source, the present invention is not limited to LEDs, and for example, organic electroluminescence (EL) may be used as the light-emitting element (light source).

[0030] [Lens array] Next, the lens array 506 will be described. FIG. 4(d) is a schematic diagram showing the configuration of the long lens array 506 mounted on the optical print head 105, as viewed from the photosensitive drum 103 side. FIG. 4(e) is a perspective view (schematic diagram) showing the general shape of the lens array 506. As shown in FIG. 4(d), the lenses in the lens array 506 are arranged in two rows along the arrangement direction of the LEDs 503 in the corresponding LED chip 639. The lenses in the lens array 506 are alternately arranged so that they contact adjacent lenses in the same row and also contact one lens in the other row. In this embodiment, the lenses in the lens array 506 are cylindrical glass rod lenses, but the material of the lenses is not limited to glass and can be plastic, and the shape of the lenses is not limited to cylindrical and can be polygonal, such as a hexagonal prism.

[0031] The dotted line Z in FIG. 4(e) indicates the optical axis of the lens of the lens array 506. The optical print head 105 can be moved by a movement mechanism (not shown) in a direction (up and down) generally along the optical axis of the lens indicated by the dotted line Z. The "optical axis of the lens" here refers to the line connecting the center of the light-emitting surface of the lens and the focal point of the lens. The direction of the optical axis is also referred to as the focusing direction hereinafter. The light beams emitted from the LEDs 503 are incident on the lenses of the lens array 506. The lenses of the lens array 506 have the function of focusing the incident light beams on the surface of the photosensitive drum 103. Therefore, when assembling the optical print head 105, the mounting position of the lens array 506 relative to the lens mounting portion 701 (see FIG. 3) is adjusted so that it is positioned as follows. That is, the mounting position of the lens array 506 is adjusted so that the distance between the light emitting surface of the LED 503 of the LED chip 639 and the light incident surface of the lens of the lens array 506 is equal to the distance between the light exit surface of the lens of the lens array 506 and the surface of the photosensitive drum 103.

[0032] [Holding body] Next, the detailed configuration of the holder 505 of the optical print head 105 will be described with reference to FIGS. 5(a), 5(b), and 6. The holder 505 is a long member that holds the substrate 502 and the lens array 506. Here, the direction of the long side of the holder 505 is the longitudinal direction, and the direction perpendicular to the longitudinal direction is the lateral direction. The direction perpendicular to the longitudinal direction and the lateral direction is the optical axis direction (hereinafter also referred to as the focusing direction). FIG. 5(a) is a perspective view showing the shape of the holder 505, with the surface that contacts the substrate 502 shown as the top surface. FIG. 5(b) is a perspective view showing the surface of the holder 505 that faces the surface of FIG. 5(a) as the top surface. FIG. 6 is a cross-sectional view corresponding to FIG. 5(a) when the substrate 502 is fixed to the holder 505.

[0033] The holder 505 holds the substrate 502 and the lens array 506. The holder 505 abuts against a mounting surface 803 of the substrate 502 on which the LED chips 639 (LEDs 503) are mounted, and has a plurality of convex seating surfaces 508 which are abutting portions that determine the position of the substrate 502 in the holder 505 in the optical axis direction. A plurality of convex seating surfaces 508 are provided in the longitudinal direction of the holder 505, and on both sides of the holder 505 in the lateral direction.

[0034] The holder 505 includes a base portion 505c, a first side wall portion 505a extending from one side in the short direction of the base portion 505c, and a second side wall portion 505b extending from the other side in the short direction of the base portion 505c. Both the side walls 505a and 505b extend from the base portion 505c in a direction away from the photosensitive drum. The base portion 505c is provided with a lens mounting portion 701 for inserting and fixing the lens array 506.

[0035] As shown in FIGS. 5A and 6, the base portion 505c of the holder 505 has two inner surfaces 510a and 510b and two outer surfaces 511a and 511b on both sides of the lens mounting portion 701 in the short direction. The two inner surfaces 510a and 510b and the two outer surfaces 511a and 511b of the base portion 505c are provided along the longitudinal direction of the holder 505 and are parallel to the longitudinal direction. The two inner surfaces 510a and 510b of the base portion 505c are surfaces that face the mounting surface 803 of the substrate 502 supported by the holder 505 in the focusing direction. On the other hand, the two outer surfaces 511a and 511b of the base portion 505c are surfaces on the opposite side from the two inner surfaces 510a and 510b in the focusing direction and face the photosensitive drum.

[0036] As shown in FIG. 5A, the holder 505 has a plurality of convex seats 508 provided on the two inner surfaces 510a and 510b of the base portion 505c. The convex seats 508 are provided on the inner surfaces 510a and 510b on both sides of the lens mounting portion 701 of the base portion 505c in the lateral direction. A plurality of convex seats 508 are provided on the two inner surfaces 510a and 510b in the longitudinal direction. Specifically, the plurality of convex seats 508 are provided at nine locations on each of the inner surfaces 510a and 510b in the longitudinal direction of the holder 505. The convex seats 508 on each of the inner surfaces 510a and 510b are positioned opposite each other in the lateral direction of the holder 505. Here, the shape of each convex seat 508 protrudes from the inner surfaces 510a and 510b in the optical axis direction in a direction away from the photosensitive drum. The contact surface of each convex seat 508 with the substrate 502 is a square of 1 mm on each side.

[0037] Furthermore, the holder 505 is provided with a backup seat 509, which is a backup portion that abuts against a housing fixing jig 900 (see FIG. 12(a)) that supports the holder 505, at a position facing the convex seat 508 in the focusing direction that is perpendicular to the longitudinal direction and the lateral direction.

[0038] As shown in FIG. 5(b), the holder 505 has a plurality of backup bearing surfaces 509 provided on the two outer surfaces 511a, 511b of the base portion 505c. The backup bearing surfaces 509 are provided on the outer surfaces 511a, 511b on both sides of the shorter side of the base portion 505c via the lens mounting portion 701. A plurality of backup bearing surfaces 509 are provided in the longitudinal direction on the two outer surfaces 511a, 511b. Specifically, the plurality of backup bearing surfaces 509 are provided at nine locations on each of the outer surfaces 511a, 511b in the longitudinal direction of the holder 505. The backup bearing surfaces 509 on the outer surfaces 511a, 511b are provided at positions facing each other in the shorter side direction of the holder 505. Here, the shape of each backup seat 509 is recessed in the optical axis direction from the outer surfaces 511a and 511b in a direction away from the photosensitive drum (concave shape relative to the holder 505). The contact surface of each backup seat 509 with the jig is a rectangle measuring 2.3 mm x 3.3 mm.

[0039] The longitudinal position of each backup seat 509 corresponds to the position of each convex seat 508 of the holder 505. In other words, the backup seat 509 formed on the holder 505 is disposed so as to face the convex seat 508 formed on the holder 505 in the optical axis direction.

[0040] 6, of the multiple convex seating surfaces 508 of the holder 505, the convex seating surfaces 508a and 508b located at both ends in the longitudinal direction of the holder 505 are preferably positioned so as to overlap at least the LED chips 639-1 and 639-29 located at both ends in the longitudinal direction of the multiple LED chips 639 arranged on the substrate 502. The reason for this is to accurately position the LED chips 639-1 to 639-29 mounted on the mounting surface 803 of the substrate 502 in the focal direction (optical axis direction). In this case, it is necessary to ensure the positions of the LED chips 639-1 and 639-29 located at both ends in the focal direction at least in the longitudinal direction of the substrate 502, and both ends of the substrate 502 need to be positioned relative to the holder 505. Therefore, it is desirable that the convex seating surfaces 508a, 508b at both ends in the longitudinal direction of the holder 505 and the LED chips 639-1, 639-29 at both ends in the longitudinal direction of the substrate 502 are arranged at positions where they overlap in the short direction of the holder 505. Note that the positions where the convex seating surfaces 508 of the holder 505 overlap with the multiple LED chips 639 arranged on the substrate 502 are not limited to the both ends in the longitudinal direction.

[0041] As shown in FIG. 3 , pins 516 and 517 are provided at both longitudinal ends of holder 505. These pins 516 and 517 abut against the seating surfaces of various jigs during the manufacturing process of the optical print head 105 to fix the position of holder 505 relative to the various jigs. These pins 516 and 517 abut against the seating surfaces of drum unit 518 in the main body of image forming apparatus 1 to ensure the position of the photosensitive drum 103 provided in drum unit 518 and the optical print head 105 in the focusing direction. Therefore, adjustments using jigs during the manufacturing process of the optical print head 105 must also be based on the tips of these pins 516 and 517. Pins 516 and 517 can move in the optical axis direction (the arrow direction, up / down direction, and focusing direction shown in FIG. 3 ), which is perpendicular to the short-side and long-side directions.

[0042] 7 is a cross-sectional view of the convex seat surface 508 of the optical print head 105, showing the positional relationship of components around the holder 505. The holder 505 has a first side wall 505a facing one end 502a of the substrate 502 in the lateral direction, and a second side wall 505b facing the other end 502b of the substrate 502 in the lateral direction. As described above, these side walls 505a and 505b are side walls that extend in a direction away from the photosensitive drum from both ends of the base 505c of the holder 505 in the lateral direction. A portion of a surface 803b of the substrate 502 opposite to a mounting surface 803 on which the LED chip 639 is provided is fixed to the holder 505 with an adhesive, which will be described later.

[0043] Convex seating surfaces 508 provided on inner surfaces 510a, 510b parallel to the longitudinal direction of holder 505 are formed so as to overlap first side wall portion 505a and second side wall portion 505b, respectively. In other words, convex seating surfaces 508 are shaped to protrude from inner surfaces 510a, 510b of base portion 505c and from the inner surfaces of side wall portions 505a, 505b.

[0044] Furthermore, backup seating surfaces 509 are provided on outer surfaces 511a and 511b parallel to the longitudinal direction of the holder 505 at positions facing the convex seating surface 508 in the optical axis direction. The holder 505 has a lens mounting portion 701 for inserting and fixing the lens array 506. As described above, the lens mounting portion 701 is provided on the base portion 505c of the holder 505. The holder 505 also has an opening 802 for inserting and fixing the substrate 502. The opening 802 is a space between a first side wall portion 505a and a second side wall portion 505b extending from both sides in the short direction of the base portion 505c. The position of the substrate 502 in the focusing direction is determined by the convex seating surface 508 of the holder 505 when the substrate 502 is inserted into the holder 505 through the opening 802 and then the surface 803b opposite the mounting surface of the substrate 502 is pressed by the substrate pressing pin 901 of the jig (see FIG. 8) at a position corresponding to the convex seating surface 508 of the holder 505. Therefore, the convex seating surface 508 of the holder 505 is managed as a precision seating surface.

[0045] 7, the backup seating surface 509 overlaps the convex seating surface 508 in the lateral direction. In other words, in the focusing direction (optical axis direction) perpendicular to the longitudinal and lateral directions, the projection surface of the backup seating surface 509 completely encompasses the projection surface of the convex seating surface 508. Specifically, the backup seating surface 509 is provided such that, with the inner surfaces of the side wall portions 505a and 505b as the reference, the length to the end of the backup seating surface 509 in the lateral direction is longer than the length to the end of the convex seating surface 508 in the lateral direction. The backup seating surface 509 is provided with a size that encompasses the area from one end to the other of each convex seating surface 508 in the longitudinal direction between one end and the other of each backup seating surface 509 in the longitudinal direction. As a result, when substrate 502 is pressed by substrate pressing pin 901 of the jig, the area that receives the pressing force is larger on backup bearing surface 509 than on convex bearing surface 508. This allows stable positioning of substrate 502 relative to holder 505. Backup bearing surface 509 of holder 505 also receives the pressing force of substrate pressing pin 901 of the jig, and is therefore similarly managed as a precision bearing surface.

[0046] Figure 8 is a cross-sectional view of optical print head 105 showing the positional relationship when substrate pressing pin 901 of the jig is pressing substrate 502, and is a view of optical print head 105 as seen from the bottom to the top of the arrow shown in Figure 7. In other words, it is a view as seen from surface 803b, the side opposite the mounting surface of substrate 502. The pressing direction of substrate pressing pin 901 coincides with the focus direction shown in Figure 7.

[0047] Mounting surface 803 of substrate 502 has non-resist portions 801, which are multiple precision bearing surfaces that abut against multiple convex bearing surfaces 508. In FIG. 8, non-resist portions 801 are invisible and are therefore indicated by dotted lines. Here, no resist is applied to non-resist portions 801, which are multiple precision bearing surfaces on mounting surface 803 of substrate 502. The reason for this is as follows. Non-resist portions 801 are locations that abut against convex bearing surfaces 508 of holder 505 when substrate pressing pin 901 presses substrate 502 in the process of fixing substrate 502 to holder 505, and are locations where substrate 502 and holder 505 are positioned. Therefore, positional accuracy in the focus direction is required at the abutting locations. However, if resist is applied to the portion of the mounting surface 803 of the substrate 502 that abuts against the convex seating surface 508, the thickness will vary and the positional accuracy in the focus direction will be lost. Therefore, a non-resist portion 801 is provided where no resist is applied.

[0048] As described above, the convex seating surfaces 508a and 508b located at both ends of the holder 505 in the longitudinal direction are configured to be positioned so as to overlap the LED chips 639-1 and 639-29 mounted on the substrate 502. However, when viewed from the side of the optical print head 105, the convex seating surfaces 508a and 508b may be positioned outside the LED chips 639-1 and 639-29 as long as they are near the LED chips 639-1 and 639-29.

[0049] Furthermore, the convex seating surface 508 and backup seating surface 509 of the holder 505 are not limited to the above-described forms. Figures 9(a) and 9(b) are diagrams showing other embodiments of the convex seating surface 508 of the optical print head 105, illustrating the positional relationship of parts around the holder 505. Figure 10 is a longitudinal cross-sectional view of the holder 505 in the configuration of Figure 9(b), looking at the holder 505 from bottom to top in Figure 9(b).

[0050] As shown in FIG. 9(a), a backup bearing surface 509 of a holder 505 may have a configuration in which a part of the short side direction of the backup bearing surface 509 has an overlap region 512 with respect to a convex bearing surface 508.

[0051] In the above-described embodiment, the convex seating surface 508 is configured to be formed so as to overlap the first side wall portion 505a and the second side wall portion 505b, but in Figures 9(b) and 10, the convex seating surface 508 may be configured to be formed at a position separated from the side wall portions 505a and 505b. The shape of the convex seating surface 508 is circular as shown in Figure 10.

[0052] Figures 11(a) and 11(b) are cross-sectional views showing the holder 505 being molded by an injection molding machine. Figure 11(a) is a cross-sectional view showing the configuration of the holder corresponding to Figures 7 and 8. Meanwhile, Figure 11(b) is a cross-sectional view showing the configuration of the holder corresponding to Figures 9(b) and 10.

[0053] The convex seating surface 508 is a precision seating surface that positions the substrate 502, and therefore requires dimensional precision after molding. As shown in FIG. 11( a), if the convex seating surface 508 is formed so as to overlap the side wall portions 505 a and 505 b, continuing to mold the holder 505 for a long period of time, for example, five years, may cause wear on the dividing piece 950, which is part of the molding machine, and may result in a deterioration in the dimensional precision of the convex seating surface 508 after molding. In this case, it is necessary to replace the dividing piece 950 of the molding machine and perform precision adjustment so that the precision of the convex seating surface 508 is maintained. On the other hand, as shown in FIG. 11( b), if the convex seating surface 508 is located away from the side wall portions 505 a and 505 b and has a circular shape, the dimensional precision of the convex seating surface 508 can be controlled by adjusting the amount of projection and recession of the round pin 951 of the molding machine. Therefore, the configuration of the convex seat surface 508 and backup seat surface 509 shown in Figure 9(b) makes it possible to easily manage the dimensional accuracy of the convex seat surface 508 without having to replace the dividing pieces of the molding machine.

[0054] In other words, a configuration in which the multiple convex seating surfaces 508 of the holder 505 are formed independently of the side wall portions 505a, 505b of the holder 505 makes it possible to easily manage the dimensional accuracy of the convex seating surfaces 508 without replacing the dividing pieces of the molding machine, even if the holder is continuously molded for a long period of time, compared to a configuration in which the convex seating surfaces 508 are formed on the side wall portions 505a, 505b of the holder 505.

[0055] In this embodiment, the shape of the convex bearing surface 508 is a square with sides of 1 mm, but it is not limited to this shape and may be a circle, a rectangle, a polygon, etc. Also, although the backup bearing surface 509 has been described as having a concave shape relative to the holder 505, it is not limited to this shape and may be a convex shape relative to the holder 505.

[0056] [Board fixing process] Next, a process will be described in which the position of the substrate 502 is adjusted relative to the holder 505 and the substrate 502 is adhesively fixed to the holder 505. Figures 12(a), 12(b), 13(a), and 13(b) are cross-sectional views showing the substrate fixing process, and are cross-sectional views in the short direction of the convex seating surface 508 of the optical print head 105.

[0057] As shown in Fig. 12(a), first, the holder 505 is placed on the housing fixing jig 900 with the opening 802 facing upward. Specifically, the position of the holder 505 is fixed by pins 516 and 517 (see Fig. 3) of the holder 505 hitting against a seating surface (not shown) of the housing fixing jig 900. Here, the housing fixing jig 900 has a plurality of support surfaces 902 that come into contact with each backup seating surface 509 of the holder 505 in the longitudinal direction of the substrate 502. The plurality of support surfaces 902 are provided at positions corresponding to each backup seating surface 509 of the holder 505.

[0058] 12(b), after the substrate 502 is inserted through the opening 802 of the holder 505 with the mounting surface 803 of the LED chip 639 facing downward, the mounting surface 803 of the substrate 502 comes into contact with the convex seating surface 508 of the holder 505. Specifically, the non-resist portion 801 on the mounting surface 803 of the substrate 502 comes into contact with the convex seating surface 508 of the holder 505.

[0059] 13(a), a surface 803b of the substrate 502 opposite to the mounting surface is pressed by a substrate pressing pin 901 of a jig at a position corresponding to each convex seating surface 508 of the holder 505. The pressing force of the substrate pressing pin 901 is, for example, 0.5 kgw.

[0060] Here, the point where the center line of the axis of the substrate pressing pin 901 (dotted line in FIG. 13(a)) intersects with the surface 803b of the substrate 502, i.e., the pressing point 903, the convex seating surface 508 of the holder 505, and the backup seating surface 509 are located on a straight line in the optical axis direction in FIG. 13(a). Therefore, when the substrate pressing pin 901 presses the substrate 502 at the pressing point 903 on the surface 803b of the substrate 502, the non-resist portion 801 on the mounting surface 803 of the substrate 502 is received by the convex seating surface 508 (precision seating surface) of the holder 505, and the backup seating surface 509 (precision seating surface) is received by the support surface 902 (precision seating surface) of the housing fixing jig 900. Therefore, it is possible to position the substrate 502 with high precision relative to the holder 505 while the substrate 502 is stably sandwiched between the substrate pressing pin 901 and the convex seating surface 508 of the holder 505 .

[0061] Thereafter, as shown in FIG. 13( b ), the holder 505 and the substrate 502 are bonded together with an adhesive 853 , and the substrate 502 is adhered and fixed to the holder 505 .

[0062] Next, using a comparative example, the effect of providing the holder 505 with the convex seat 508 that contacts the substrate 502 and the backup seat 509 that contacts the support surface 902 of the housing fixing jig 900 will be explained.

[0063] 14(a) and 14(b) show cross-sectional views of the configuration of Comparative Example 1 in which the holder 505 is not provided with the convex seat surface 508. Fig. 14(a) is a cross-sectional view before the substrate 502 is fixed to the holder 505, and Fig. 14(b) is a cross-sectional view after the substrate 502 has been pressed by the substrate pressing pin 901 and adhered and fixed to the holder 505.

[0064] As shown in FIG. 14( a), when the holder 505 does not have a convex seating surface 508, the substrate 502 and the end face 510 of the holder 505 are in contact with each other over the entire longitudinal length of the holder 505. Therefore, the positioning of the substrate 502 in the optical axis direction is performed by the end face 510 of the holder 505 over the entire longitudinal length of the holder 505. Therefore, the surface accuracy of the end face 510 of the holder 505 is important for accurately positioning the substrate 502 relative to the holder 505. However, when molding a long-shaped component, it is generally difficult to achieve surface accuracy, such as flatness and parallelism, over the entire longitudinal length, resulting in a difference in height (waviness) in the longitudinal direction. Therefore, when the substrate 502 is pressed by the substrate pressing pin 901 to position the substrate 502 relative to the holder 505, the mounting surface 803 of the substrate 502 conforms to the end face 510 of the holder 505, as shown in FIG. 14( b). Therefore, the substrate 502 is positioned and fixed in a posture that picks up the difference in height (swell) component in the longitudinal direction of the end face 510 of the holder 505. As a result, the position of the LED chip 639 on the substrate 502 varies in the optical axis direction, which may cause the position of the imaging point on the surface of the photosensitive drum 103 to vary, leading to deterioration of image quality.

[0065] 15 shows a cross-sectional view of the configuration of Comparative Example 2 in which convex seating surface 508 is provided on holder 505 and backup seating surface 509 is not provided. Fig. 15 is a cross-sectional view after substrate 502 is pressed by substrate pressing pin 901 at the position of convex seating surface 508 in the longitudinal direction of holder 505 and adhesively fixed to holder 505.

[0066] 15 is managed as a precision bearing surface, as described above. Therefore, when substrate 502 is pressed by substrate pressing pin 901, substrate 502 can come into contact with convex bearing surface 508 without picking up any height difference (waviness) component in the longitudinal direction of holder 505.

[0067] 15 , backup seat 509 is not provided at a position facing convex seat 508 in the longitudinal direction of holder 505. Therefore, end face (outer surface) 511 of holder 505 extending over the entire longitudinal direction abuts against support surface 902 of housing fixing jig 900 extending over the entire longitudinal direction. For the reasons described above, it is difficult to ensure surface precision for end face 511 of holder 505, just as it is for end face 510 of holder 505 extending over the entire longitudinal direction. Therefore, end face 511 of holder 505 also has a difference in height (waviness) in the longitudinal direction, and therefore end face 511 does not stably abut against support surface 902 of housing fixing jig 900. As a result, the forces that substrate 502 receives from convex seat 508 are not equal at multiple pressing points 903 in the longitudinal direction (see FIG. 13( a) ), and substrate 502 cannot be positioned stably.

[0068] 7(a), in this embodiment, a backup seat 509 (precision seat) is provided at a position opposite to the convex seat 508 in the longitudinal direction of the holder 505. This allows the holder 505 to abut against the support surface 902 of the housing fixing jig at the backup seat 509 with high precision.

[0069] 13(a) 。 Therefore, when the substrate pressing pin 901 presses the substrate 502 at the pressing point 903 on the substrate 502, the substrate 502 is received by the convex seating surface 508 (precision seating surface) of the holder 505, and the backup seating surface 509 (precision seating surface) is received by the support surface 902 (precision seating surface) of the housing fixing jig 900. Therefore, at any pressing point 903 in the longitudinal direction, the force acting on the substrate 502 (the force that the substrate 502 receives from the substrate pressing pin 901 and the force that the substrate 502 receives from the convex seating surface 508 of the holder 505) is equal. Therefore, substrate 502 can be positioned and fixed with high precision relative to holder 505 in a state where it is stably sandwiched between substrate pressing pin 901 and convex seat surface 508 of holder 505 .

[0070] In the above-described embodiment, the holder 505 is provided with a plurality of convex seats 508 serving as abutment portions and a plurality of backup seats 509 serving as backup portions, but the present invention is not limited to this. For example, if the outer surfaces 511a, 511b of the base portion of the holder 505 are not supported by the housing fixing jig 900 when positioning the substrate 502 relative to the holder 505, it is not necessarily necessary to provide the backup seats 509. In this case, by bringing the mounting surface 803 of the substrate 502 into contact with a plurality of convex seats 508 provided in the longitudinal direction of the holder 505, the substrate 502 can be accurately positioned and fixed to the holder 505. [Explanation of symbols]

[0071] 1...Image forming device 103...Photosensitive drum 105...Optical print head 500...Exposure unit 502... Substrate 505...Holding body 505a ...first side wall portion 505b ... second side wall portion 505c...base part 506...Lens array 508…Convex seat surface 509 ...Backup seat 510a,510b...inner surface 511a,511b...outer surface 516,517 … pins 639...LED chip 701...Lens mounting part 801 ... Non-resist area 802...Opening 803...Mounting surface 803b…face 900...Housing fixing jig 901 ... Board pressure pin 902...support surface 903...Pressure point

Claims

1. a substrate on which a plurality of light-emitting elements for emitting light to expose a photosensitive member are mounted along a longitudinal direction that is the direction of the rotation axis of the photosensitive member; a lens that focuses the light emitted from the light-emitting element onto the photosensitive member; a holder that holds the substrate and the lens, the holder has a plurality of contact portions that come into contact with a mounting surface of the substrate on which the light-emitting element is mounted and determine the position of the substrate on the holder in the optical axis direction, the plurality of abutment portions are arranged on both sides of the holder in a short direction perpendicular to the longitudinal direction, and the plurality of abutment portions are arranged along the longitudinal direction of the holder, the holder further includes a plurality of backup portions configured to abut against a jig supporting the holder, at positions facing the plurality of abutment portions in an optical axis direction perpendicular to the longitudinal direction and the lateral direction, respectively. An exposure head characterized by:

2. Each of the plurality of backup portions has a shape recessed from the outer surface of the holder toward a direction away from the photosensitive body in the optical axis direction.

2. The exposure head according to claim 1.

3. The contact surfaces of each of the plurality of backup parts with the jig are rectangular in shape.

2. The exposure head according to claim 1.

4. a projection surface of the backup portion completely encompasses a projection surface of the contact portion in an optical axis direction perpendicular to the longitudinal direction and the lateral direction; 4. The exposure head according to claim 1, wherein the first and second electrodes are arranged parallel to each other.

5. the mounting surface of the substrate has a plurality of precision bearing surfaces that come into contact with the plurality of contact portions, No resist is applied to the precision bearing surfaces.

5. The exposure head according to claim 1, wherein the first and second electrodes are arranged parallel to each other.

6. the substrate is adhesively fixed to the holder in a state in which the precision seating surfaces of the mounting surface of the substrate and the contact portions of the holder are in contact with each other; 6. The exposure head according to claim 5.

7. the holder includes a base portion having an opening into which the lens is inserted, a first side wall portion extending from one side of the base portion in a widthwise direction in a direction away from the photosensitive body, and a second side wall portion extending from the other side of the base portion in the widthwise direction in a direction away from the photosensitive body, the plurality of contact portions of the holder are provided on the first side wall portion and the second side wall portion of the holder; 7. The exposure head according to claim 1, wherein the first and second electrodes are arranged parallel to each other.

8. the holder includes a base portion having an opening into which the lens is inserted, a first side wall portion extending from one side of the base portion in a widthwise direction in a direction away from the photosensitive body, and a second side wall portion extending from the other side of the base portion in the widthwise direction in a direction away from the photosensitive body, the plurality of contact portions of the holder are formed independently of the first side wall portion and the second side wall portion of the holder.

7. The exposure head according to claim 1, wherein the first and second electrodes are arranged parallel to each other.

9. The substrate has a plurality of chips each having a plurality of light-emitting elements arranged in a longitudinal direction, which is the direction of the rotation axis of the photosensitive member, Among the plurality of contact portions of the holder, the contact portions located at both ends in the longitudinal direction of the holder are arranged at positions overlapping with at least the chips located at both ends in the longitudinal direction among the plurality of chips arranged on the substrate.

9. The exposure head according to claim 1, wherein the first and second electrodes are arranged parallel to each other.

10. A photoreceptor; and an exposure head according to any one of claims 1 to 9 that exposes the photosensitive member. An image forming apparatus characterized by:

Images