Exposure device and image forming apparatus

Abstract

To achieve strength required for securing assemblability of an exposure head and positioning the exposure head and reduction of deformation of a substrate and a lens array by thermal expansion differences.SOLUTION: An exposure device has an elongated shape extending in an axial direction of a photosensitive member and exposes the photosensitive member. The exposure device includes: a substrate on which a plurality of light emitting elements are arranged; a lens array configured to collect light emitted from the light emitting elements on the photosensitive member; a housing configured to hold the substrate and the lens array; a housing support member configured to support the housing over a longitudinal direction; a first coupling member which fixes the housing and the housing support member at one end in the longitudinal direction; and a second coupling member which fixes the housing and the housing support member at the other end in the longitudinal direction. A hardness of the first coupling member is higher than that of the second coupling member.SELECTED DRAWING: Figure 15

Description

[Technical field]

[0001] The present invention relates to an exposure device that exposes a photoconductor and an image forming apparatus equipped with the exposure device. [Background technology]

[0002] Conventionally, an exposure head used in an electrophotographic image forming apparatus is known that includes a substrate on which a plurality of light-emitting elements are arranged along the axial direction of a photosensitive drum, a lens that collects light emitted from the plurality of light-emitting elements, and a holder that holds the substrate and the lens. In this exposure head, the light emitted from the plurality of light-emitting elements is collected through the lens to expose a photosensitive drum.

[0003] In an image forming device equipped with the above-mentioned exposure head, heat generated by the substrate during light emission can cause differences in thermal expansion within the exposure head, such as the light-emitting elements, lens array, and the housing that holds them, which can affect the optical characteristics.

[0004] Therefore, in Patent Document 1 (JP 2021-74943 A), a heat dissipation member is provided on the substrate on which the light-emitting element is mounted, in contact with the opposing surface of the housing that holds the substrate, thereby efficiently dissipating heat from the housing and suppressing deformation of the substrate and lens array. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-74943 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in order to prevent deformation of the substrate, lens array, and housing due to heat generation from the substrate and to reduce the temperature rise inside the exposure head, the above-mentioned heat dissipation member alone is insufficient, and a cooling mechanism for cooling the substrate is required.

[0007] Therefore, a configuration is considered in which a housing support member that supports the housing is provided in the exposure head, and the substrate is cooled by airflow. In this case, the housing support member through which the airflow passes must be fixed to the housing to ensure strength from the viewpoint of assembling the exposure head and positioning on the main body. On the other hand, because the housing support member is fixed to the housing, deformation due to the difference in thermal expansion between the housing and the housing support member may induce deformation of the substrate or lens array, which may affect the optical characteristics.

[0008] An object of the present invention is to achieve both the strength required for ease of assembly and positioning of the exposure head and the reduction of deformation of the substrate and lens array due to differences in thermal expansion. [Means for solving the problem]

[0009] A typical configuration of the present invention for achieving the above-mentioned object is an exposure device having an elongated shape extending in the axial direction of a photosensitive body and exposing the photosensitive body, the exposure device having a substrate on which a plurality of light-emitting elements are arranged, a lens array that focuses light emitted from the light-emitting elements onto the photosensitive body, a housing that holds the substrate and the lens array, a housing support member that supports the housing in the longitudinal direction, a first connecting member that fixes the housing and the housing support member at one longitudinal end, and a second connecting member that fixes the housing and the housing support member at the other longitudinal end, the first connecting member having a harderness than the second connecting member. Effect of the Invention

[0010] According to the present invention, it is possible to achieve both the strength required for ease of assembly and positioning of the exposure apparatus and the reduction of deformation of the substrate and the lens array due to differences in thermal expansion. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view showing a schematic configuration of an image forming apparatus. [Diagram 2] FIG. 1 is a perspective view of an image forming apparatus; [Diagram 3]1A and 1B are perspective views showing the configuration of the drum unit and the developing unit and its surroundings. [Figure 4] 1A, 1B, and 1C are diagrams showing a substrate in an exposure head, and 1D and 1E are diagrams showing a lens array. [Diagram 5] A perspective view of an exposure head [Figure 6] FIG. 2 is a perspective view showing the cartridge tray, the inner door in a closed state, and the exposure head in the exposure position. [Figure 7] FIG. 1 is a perspective view showing a cartridge tray, an inner door in an open state, and an exposure head in a retracted position. [Figure 8] FIG. 13 is a perspective view of the positioning member after it is attached; [Figure 9] FIG. 3 is a perspective view of the positioning member before it is attached; [Figure 10] FIG. 13 is a perspective view showing the shape of a positioning member; [Figure 11] FIG. 1 is a cross-sectional view showing a cooling structure of an exposure head. [Figure 12] Perspective view of the duct unit [Figure 13] Perspective view of the cartridge tray and lift duct from below [Figure 14] FIG. 1 is a cross-sectional view showing a cooling structure of an exposure head. [Figure 15] FIG. 1 is a perspective view of an exposure head according to a first embodiment, seen from below. [Figure 16] FIG. 1 is a perspective view showing one of the connecting portions between the housing and the housing support member according to the first embodiment; [Figure 17] FIG. 13 is a perspective view showing the other connection portion between the housing and the housing support member; [Figure 18] FIG. 11 is a perspective view showing one of the connecting portions between the housing and the housing support member according to the second embodiment; [Figure 19] FIG. 13 is a perspective view showing one of the connecting portions between the housing and the housing support member according to the third embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Preferred embodiments of the present invention will be described below with reference to the drawings. However, the components described in the following description are merely examples, and the present invention is not limited to the embodiments described in the following description.

[0013] Example 1 (Image forming device) First, a schematic configuration of an image forming apparatus 100 will be described. FIG. 1 is a cross-sectional view showing a schematic configuration of the image forming apparatus. FIG. 2 is a perspective view showing the appearance of the image forming apparatus. The image forming apparatus shown in FIG. 1 and FIG. 2 is an example of an image forming apparatus equipped with a reading device, but the image forming apparatus may not be equipped with a reading device. In addition, the embodiment is not limited to a so-called tandem type color image forming apparatus equipped with a plurality of photosensitive drums as shown in FIG. 1, but may be a color image forming apparatus equipped with one photosensitive drum or an image forming apparatus that forms a monochrome image.

[0014] The image forming apparatus 100 shown in FIG. 1 includes four image forming units 101Y, 101M, 101C, and 101K (hereinafter, collectively referred to simply as "image forming units 101") that form toner images of yellow, magenta, cyan, and black, respectively.

[0015] The image forming units 101Y, 101M, 101C, and 101K are provided with photosensitive drums 102Y, 102M, 102C, and 102K (hereinafter, collectively referred to simply as "photosensitive drums 102"), which are examples of photosensitive bodies (image carriers). These photosensitive drums are arranged at a distance from each other. The photosensitive drums may be photosensitive belts.

[0016] The image forming units 101Y, 101M, 101C, and 101K are equipped with chargers 103Y, 103M, 103C, and 103K (hereinafter collectively referred to simply as "charger 103") as charging means for charging the photosensitive drums 102Y, 102M, 102C, and 102K, respectively.

[0017] The image forming units 101Y, 101M, 101C, and 101K are equipped with LED (Light Emitting Diode, hereinafter referred to as LED) exposure units 500Y, 500M, 500C, and 500K (hereinafter collectively referred to as "exposure units 500") as exposure means that emit light to expose the photosensitive drums 102Y, 102M, 102C, and 102K.

[0018] Furthermore, the image forming units 101Y, 101M, 101C, and 101K each include developing units 105Y, 105M, 105C, and 105K (hereinafter collectively referred to simply as "developing units 105") that develop the electrostatic latent image on the photosensitive drum 102 with toner and develop a toner image of each color on the photosensitive drum 102. The letters Y, M, C, and K attached to the reference characters indicate the colors of the toner.

[0019] The image forming apparatus 100 shown in FIG. 1 is a so-called "bottom exposure type" image forming apparatus in which a photosensitive drum 102 is exposed from below. In the image forming apparatus 100 employing the bottom exposure type, an exposure unit 500 is disposed below the photosensitive drum 102. The following description will be given on the premise that the image forming apparatus employs the bottom exposure type. Note that, although not shown in the drawings, an embodiment may also be an image forming apparatus employing an "top exposure type" in which a photosensitive drum is exposed from above.

[0020] The image forming apparatus 100 includes an intermediate transfer belt 106 onto which a toner image formed on a photosensitive drum 102 is transferred, and primary transfer rollers 107Y, 107M, 107C, and 107K (hereinafter collectively referred to as "primary transfer rollers 107") that sequentially transfer the toner image formed on the photosensitive drum 102 onto the intermediate transfer belt. Note that, other than the intermediate transfer method using the intermediate transfer belt, a direct transfer method in which an image is directly transferred from the photosensitive drum to a sheet may also be used.

[0021] The image forming apparatus 100 also includes a secondary transfer roller 109 that transfers the toner image on the intermediate transfer belt 106 onto a recording material S transported from a paper feed unit 108, and a fixing device 110 that fixes the secondarily transferred image onto the recording material S.

[0022] After the primary transfer, toner remains on the surfaces of the photosensitive drums 102Y, 102M, 102C, and 102K. The remaining toner is removed by drum cleaning devices 111Y, 111M, 111C, and 111K (hereinafter, also collectively referred to as "drum cleaning devices 111") and collected in a collected toner container 112.

[0023] After the secondary transfer, toner remains on the surface of the intermediate transfer belt 106. This residual toner is removed by a belt cleaning device and collected in a collected toner container 112.

[0024] Image forming apparatus 100 also includes detachable duct unit 606 (see FIGS. 11 and 12). Duct unit 606 is disposed below image forming section 101 and above paper feed section 108. Duct unit 606 is in communication with exposure unit 500 and is an exposure cooling unit for cooling exposure unit 500 (exposure head 104) by airflow.

[0025] (Image formation process) Next, the image forming process of the image forming apparatus 100 will be briefly described. The charger 103Y charges the surface of the photosensitive drum 102Y. The exposure unit 500Y exposes the surface of the photosensitive drum 102Y charged by the charger 103Y. As a result, an electrostatic latent image is formed on the photosensitive drum 102Y. Next, the developer 105Y develops the electrostatic latent image formed on the photosensitive drum 102Y with yellow toner. The yellow toner image developed on the surface of the photosensitive drum 102Y is transferred onto the intermediate transfer belt 106 by the primary transfer roller 107Y. Magenta, cyan, and black toner images are also formed in the same image forming process and transferred to the intermediate transfer belt 106 so as to be superimposed on each other.

[0026] The toner images of each color transferred onto the intermediate transfer belt 106 are transported to a secondary transfer section T2 by the intermediate transfer belt 106. The toner images transported to the secondary transfer section T2 are transferred by a secondary transfer roller 109 onto a recording material S transported from a paper feed section (paper feed cassette) 108.

[0027] The recording material S is stored in a stacked form in the paper feed unit 108, and is fed to the conveying path 113 in accordance with the image formation timing. The paper is fed by the friction of the paper feed roller 114 causing the leading edge of the recording material S to bounce up, and only one sheet of the recording material S is conveyed to the conveying path 113 by a pair of paper separating conveying rollers 115a, 115b for preventing double feeding of the recording material S. Thereafter, the recording material S conveyed by the pair of conveying rollers 116a, 116b passes through the conveying path 113 and is conveyed to the pair of registration rollers 117a, 117b where it is temporarily stopped. Incidentally, the pair of registration rollers 117a, 117b perform skew correction and timing correction, and then conveys the recording material S to the secondary transfer unit T2.

[0028] The recording material S onto which the toner image has been transferred at the secondary transfer portion T2 is conveyed to a fixing device 110. The fixing device 110 fixes the toner image onto the recording material S by heat and pressure. The recording material S onto which the toner image has been fixed by the fixing device 110 is discharged to a paper discharge portion 118.

[0029] As shown in FIG. 1, the image forming apparatus 100 includes toner containers 119Y, 119M, 119C, and 119K (hereinafter, collectively referred to simply as "toner containers 119"). When an image is formed, the amount of toner in the developing unit 600 (described later) decreases. At that time, the toner is supplied to the developing unit 600 (described later) from toner containers 119Y, 119M, 119C, and 199K provided corresponding to the image forming sections 101Y, 101M, 101C, and 101K. That is, in the developing unit 600 (described later) included in the image forming apparatus 100 described in this embodiment, new toner is replenished from the toner container 119, while a part of the excess toner is transported to the collected toner container 112 as residual toner.

[0030] (Drum unit and developing unit) A drum unit 601, which is an example of a replaceable unit, is attached to the image forming apparatus 100 of this embodiment. The drum unit 601 is a cartridge that is replaced by an operator such as a user or a maintenance technician. The drum unit 601 (Y, M, C, K) of this embodiment includes photosensitive drums 102 (Y, M, C, K) rotatably supported on a frame of the drum unit 601.

[0031] In addition, the image forming apparatus 100 of this embodiment is provided with a developing unit 600 separate from the drum unit 601. The developing unit 600 of this embodiment is a cartridge in which the developing device 105 and the toner storage unit shown in FIG. 1 are integrated. The developing device 105 is provided with a developing sleeve which is a developer carrier that carries a developer. The developing unit 600 is provided with a plurality of gears for rotating a screw for stirring the toner and carrier. When these gears deteriorate over time, an operator removes the developing unit 600 from the main body of the image forming apparatus 100 and replaces it. In addition, a certain amount of toner is removed from the developing unit 600 as residual toner and transported to the collected toner container 112. The embodiment of the drum unit 601 and the developing unit 600 may be a process cartridge in which the drum unit 601 and the developing unit 600 are integrated.

[0032] Further, the image forming apparatus 100 includes a cartridge tray 605 (605Y, 605M, 605C, 605K) for each image forming portion (see FIGS. 6 and 7). The drum unit 601 and the developing unit 600 are supported by the cartridge tray 605 for each image forming portion, guided in the axial direction of the photosensitive drum, and inserted into and removed from the main body of the image forming apparatus 100.

[0033] As shown in FIG. 3(a) and FIG. 3(b), one side of the cartridge tray 605 is attached to a front side plate 602 and the other side is attached to a rear side plate 603 in the axial direction of the photosensitive drum. The front side plate 602 is made of sheet metal and forms a part of the housing (frame) of the main body of the image forming apparatus 100 at the front side of the main body of the image forming apparatus 100. The rear side plate 603 is made of sheet metal and forms a part of the housing (frame) of the main body of the image forming apparatus 100 at the rear side of the main body of the image forming apparatus 100. The front side plate 602 and the rear side plate 603 are arranged facing each other on one side and the other side in the axial direction of the photosensitive drum, and a sheet metal beam (not shown) is provided between them. The front side plate 602, the rear side plate 603, and the beam (not shown) each form a part of the frame of the image forming apparatus 100. Here, with respect to the image forming apparatus of this embodiment or its components, the front side or near side is the side where the drum unit 601 and the developing unit 600 are inserted into and removed from the main body of the image forming apparatus 100.

[0034] An opening 602a is formed in the front side plate 602 so that the drum unit 601 and the developing unit 600 can be inserted and removed from the front side of the image forming apparatus 100. The drum unit 601 and the developing unit 600 are mounted in a predetermined position (mounting position) of the main body of the image forming apparatus 100 through the opening 602a.

[0035] Image forming apparatus 100 includes inner doors 120Y, 120M, 120C, and 120K (hereinafter collectively referred to as "inner door 120") that cover the front side of both drum unit 601 and developing unit 600 that are mounted in the mounting position. Inner door 120 is pivotally supported on the front side of cartridge tray 605 and is rotatable within a predetermined range relative to cartridge tray 605. That is, inner door 120 is provided so as to be openable and closable relative to the image forming apparatus.

[0036] Furthermore, a front cover 604 that forms the exterior of the device is provided at the front side of the image forming apparatus 100. One end of the front cover 604 is fixed to the front side of the device body of the image forming apparatus 100 by a hinge, and the front cover 604 is rotatable relative to the device body of the image forming apparatus 100 by the hinge. The front cover 604 is provided forward of the inner door 120 in the axial direction of the photosensitive drum. In the closed state shown in FIG. 2, the front cover 604 covers the entirety of the multiple inner doors 120 lined up in the left-right direction, forming the exterior of the front side of the device.

[0037] Therefore, the replacement work of the drum unit 601 and the developing unit 600 is performed by an operator in the following procedure: The operator opens the front cover 604, then opens the inner door 120 as shown in Figures 3(a) and 3(b), and removes the drum unit 601 or the developing unit 600 from inside the main body of the apparatus. Then, the operator inserts a new drum unit 601 or the developing unit 600, closes the inner door 120, and further closes the front cover 604, completing the replacement work.

[0038] Although not shown, the image forming apparatus 100 according to this embodiment includes a movement mechanism that moves the exposure head 104 (exposure unit 500) to an exposure position or a retracted position (separated position) relative to the photosensitive drum 102. The movement mechanism is provided in the image forming apparatus 100, and moves the exposure head 104 to the exposure position or to a retracted position retracted from the exposure position.

[0039] In this embodiment, as shown in Fig. 6, the movement mechanism moves the exposure head 104 (exposure unit 500) in a direction away from the photosensitive drum 102 in conjunction with the operation of opening the inner door 120, and retracts the exposure head 104 to a retracted position. On the other hand, as shown in Fig. 7, the movement mechanism moves the exposure head 104 in a direction approaching the photosensitive drum 102 in conjunction with the operation of closing the inner door 120, and moves the exposure head 104 to an exposure position.

[0040] Furthermore, in this embodiment, the movement mechanism moves not only the exposure head 104 (exposure unit 500) but also the development unit 600 to the development position or to a retracted position retracted from the development position. That is, the movement mechanism moves the development unit 600 in a direction away from the photosensitive drum 102 in conjunction with the operation of opening the inner door 120, and retracts the development unit 600 to the retracted position. On the other hand, the movement mechanism moves the development unit 600 in a direction approaching the photosensitive drum 102 in conjunction with the operation of closing the inner door 120, and moves the development unit 600 to the development position.

[0041] The movement mechanism (lifting duct 609, rotating arm 610, and link member (not shown)) will be described later.

[0042] In the following description, the front plate 602 side is defined as the front side (near side or front side) and the rear plate 603 side is defined as the rear side (rear side or back side) with respect to the device body. In addition, when the photosensitive drum 102K on which the electrostatic latent image of the black toner image is formed is taken as a reference, the side on which the photosensitive drum 102Y on which the electrostatic latent image of the yellow toner image is formed is defined as the left side. When the photosensitive drum 102Y on which the electrostatic latent image of the yellow toner image is formed is taken as a reference, the side on which the photosensitive drum 102K on which the electrostatic latent image of the black toner image is formed is defined as the right side. Furthermore, the direction perpendicular to the front-rear direction and the left-right direction defined here and vertically upward is defined as the up direction, and the direction perpendicular to the front-rear direction and the left-right direction defined here and vertically downward is defined as the down direction. The defined front direction F, rear direction B, left direction L, right direction R, up direction U, and down direction D are shown in FIG. 2, FIG. 3(a), and FIG. 3(b).

[0043] The rotation axis direction of the photosensitive drum 102 described in the following text is the same as the front-rear direction shown in FIG. 3(a) and FIG. 3(b). The longitudinal direction of the exposure head 104 is also the same as the front-rear direction shown in FIG. 3(a) and FIG. 3(b). That is, the rotation axis direction of the photosensitive drum 102 and the longitudinal direction of the exposure head 104 are the same as each other. One end side in the rotation axis direction of the photosensitive drum 102 means the front side defined here, and the other end side means the rear side defined here. One end side and the other end side in the front-rear direction also correspond to the front side and the rear side defined here. One end side in the left-right direction means the left side defined here, and the other end side means the right side defined here. The longitudinal direction of the exposure head 104 described in the following text means the front-rear direction defined here, and the short side direction of the exposure head 104 means the left-right direction defined here.

[0044] (Exposure unit) Next, a description will be given of the exposure unit 500 including the exposure head 104. The exposure unit 500 shown in Fig. 1 includes the exposure head 104 (see Fig. 5) that exposes the photosensitive drum 102.

[0045] (Exposure head configuration) Next, the exposure head (optical print head) 104 provided in the exposure unit 500 will be described. Here, as an example of an exposure method adopted in an electrophotographic image forming apparatus, there is a laser beam scanning exposure method in which a semiconductor laser irradiation beam is scanned by a rotating polygon mirror or the like and a photosensitive drum is exposed via an f-θ lens or the like. The "exposure head 104" described in this embodiment is used for an LED exposure method in which the photosensitive drum 102 is exposed to light using light emitting elements such as LEDs arranged along the rotation axis direction of the photosensitive drum 102, and is not used for the laser beam scanning exposure method mentioned above.

[0046] The exposure head 104 described in this embodiment is provided vertically below the rotation axis of the photosensitive drum 102, and an LED 503 included in the exposure head 104 exposes the photosensitive drum 102 from below. Fig. 5 is a schematic perspective view of the exposure head 104 included in the image forming apparatus 100 of this embodiment.

[0047] The exposure head 104 has an elongated shape (longitudinal shape) extending in the direction of the rotation axis of the photosensitive drum 102. The exposure head 104 also includes a housing 505, a substrate 502 (see FIG. 4(a)), a lens array 506, and a housing support member 510 (see FIG. 5).

[0048] (Housing) Housing 505 holds substrate 502 and lens array 506. Housing 505 has opening 701 as a lens attachment portion for attaching lens array 506. Housing 505 is made of metal. For example, housing 505 is formed into a U-shape by pressing a metal plate such as a thin iron plate.

[0049] Further, the housing 505 of the exposure head 104 is provided with a positioning pin 508 as a first fixed member and a positioning pin 509 as a second fixed member. Both the positioning pin 508 and the positioning pin 509 are examples of metal pins. The positioning pin 508 and the positioning pin 509 are fixed to both ends of the housing 505 in the longitudinal direction. The positioning pin 508 is fixed to the housing 505 on one side (front side) of the lens array 506 in the axial direction of the photosensitive drum 102, and protrudes from both sides of the housing 505 in the optical axis direction of the lens array 506. The positioning pin 509 is fixed to the housing 505 on the other side (rear side) of the lens array 506 in the axial direction of the photosensitive drum 102, and protrudes from both sides of the housing 505 in the optical axis direction of the lens array 506.

[0050] In order to ensure the distance between the surface of the photosensitive drum 102 and the light emission surface of the lens array 506 of the exposure head 104 with high precision, the position of the positioning surface of the shaft tip of the positioning pins 508, 509 is adjusted with reference to the housing 505, and the positioning pins 508, 509 are crimped to the housing 505. Note that the fixing of the positioning pins 508, 509 to the housing 505 is not limited to this, and for example, the metallic positioning pins 508 and 509 may be fixed to the metallic housing 505 by welding. Thus, in this embodiment, the positioning pins 508 and 509 are integrated with the housing 505.

[0051] When the exposure head 104 is moved to the exposure position, the positioning pins 508, 509 of the exposure head 104 come into contact with predetermined locations of the drum unit 601 that supports the photosensitive drum 102. This keeps the distance between the exposure head 104 and the surface of the photosensitive drum 102 constant at the exposure position.

[0052] (substrate) Next, the substrate 502 will be described. Fig. 4(a) is a schematic perspective view of the substrate 502 in the exposure head 104. Fig. 4(b) is a diagram showing an arrangement of a plurality of LEDs 503 provided on the substrate 502, and Fig. 4(c) is an enlarged view of Fig. 4(b).

[0053] An LED chip 639 is mounted on the substrate 502. As shown in Fig. 4(a), the LED chip 639 is provided on one surface of the substrate 502, and a long FFC connector 504 is provided on the other surface (the surface opposite to the side on which the light emitting elements are arranged). The FFC connector 504 is attached to the lower surface of the substrate 502 so that its longitudinal direction is along the longitudinal direction of the substrate 502. The substrate 502 is provided with wiring for supplying signals to each LED chip 639. One end of a flexible flat cable (not shown, hereinafter abbreviated as FFC) as an example of a cable is connected to the FFC connector 504.

[0054] Image forming apparatus 100 is provided with a control board (not shown) that includes a control unit and a connector. The other end of the FFC is connected to the connector. That is, the FFC electrically connects the control board that includes the control unit and substrate 502. A control signal (drive signal) is input to substrate 502 from the control unit of image forming apparatus 100 via the FFC and FFC connector 504. LED chip 639 is driven by the control signal input to substrate 502.

[0055] The LED chip 639 mounted on the substrate 502 will be described in more detail. As shown in FIG. 4(b) and FIG. 4(c), a plurality of LED chips 639-1 to 639-29 (29 chips) each having a plurality of LEDs 503 (one example of a light-emitting element) arranged thereon are arranged on one surface of the substrate 502. Each of the LED chips 639-1 to 639-29 has 516 LEDs 503 arranged in a row in its longitudinal direction. In the longitudinal direction of the LED chip 639, the center-to-center distance k2 between adjacent LEDs 503 corresponds to the resolution of the image forming apparatus 100. Since the resolution of the image forming apparatus 100 of this embodiment is 1200 dpi, the LEDs 503 are arranged in a row in the longitudinal direction of the LED chips 639-1 to 639-29 such that the center-to-center distance between adjacent LEDs 503 is 21.16 μm. Therefore, the exposure range of the exposure head 104 of this embodiment is about 314 mm. The photosensitive layer of the photosensitive drum 102 is formed with a width of 314 mm or more. Since the length of the long side of an A4 size recording paper and the length of the short side of an A3 size recording paper are 297 mm, the exposure head 104 of this embodiment has an exposure range capable of forming images on the A4 size recording paper and the A3 size recording paper.

[0056] The LED chips 639-1 to 639-29 are alternately arranged in two rows along the rotation axis direction of the photosensitive drum 102. That is, as shown in FIG. 4B, the odd-numbered LED chips 639-1, 639-3, . . . 639-29 counting from the left side are mounted in a row in the longitudinal direction of the substrate 502. Also, the even-numbered LED chips 639-2, 639-4, . . . 639-28 counting from the left side are mounted in a row in the longitudinal direction of the substrate 502. By arranging the LED chips 639 in this manner, as shown in FIG. 4C, in the longitudinal direction of the LED chips 639, the center-to-center distance k1 between the LEDs 503 arranged at one end of one LED chip 639 and the other end of the other LED chip 639 in different adjacent LED chips 639 can be made equal to the center-to-center distance k2 between the adjacent LEDs 503 on one LED chip 639.

[0057] In this embodiment, the light emitting element is an LED, but an OLED (Organic Light Emitting Diode) may be used. The OLED is also called an organic EL (Organic Electro-Luminescence) and is a current-driven light emitting element. The OLEDs are arranged in a line along the main scanning direction (the direction of the axis of rotation of the photosensitive drum 102) on a TFT (Thin Film Transistor) substrate, and are electrically connected in parallel by power supply wiring that is also arranged along the main scanning direction.

[0058] (Lens array) Next, the lens array 506 will be described. FIG. 4(d) is a schematic diagram of the lens array 506 when viewed from the photosensitive drum 102 side. FIG. 4(e) is a schematic perspective view of the lens array 506. As shown in FIG. 4(d), the lens array 506 has a plurality of lenses arranged in two rows along the arrangement direction of the plurality of LEDs 503. Each lens is arranged so that one lens in one row is in contact with both of the lenses adjacent to the other row in the arrangement direction of the lenses in the other row, and this arrangement is repeated alternately. Each lens is a cylindrical glass rod lens. The material of the lens is not limited to glass, and may be plastic. The shape of the lens is not limited to cylindrical, and may be a polygonal column such as a hexagonal column.

[0059] The dotted line Z in FIG. 4(e) indicates the optical axis of the lens. The exposure head 104 can be moved by a moving mechanism (not shown) in a direction (up and down) along the optical axis of the lens indicated by the dotted line Z. The optical axis of the lens here means a line connecting the center of the light emission surface of the lens and the focal point of the lens. The radiation light emitted from the LED 503 is incident on the lens of the lens array 506. The lens has a function of concentrating the incident radiation light on the surface of the photosensitive drum 102. The mounting position of the lens array 506 with respect to the opening 701 (see FIG. 5), which is the lens mounting portion, is adjusted when the exposure head 104 is assembled. At this time, the mounting position of the lens array 506 is adjusted so that the distance between the light emitting surface of the LED 503 and the light incident surface of the lens and the distance between the light emission surface of the lens and the surface of the photosensitive drum 102 are approximately equal.

[0060] (Housing support member) The housing support member 510 supports the housing 505 holding the substrate 502 and the lens array 506 in the longitudinal direction, and is fixed to the housing 505 by a fixing method described below. The housing support member 510 is a longitudinal member extending in the axial direction of the photosensitive drum 102. The housing support member 510 is formed in a U-shape. The housing support member 510 has a plurality of openings 510a provided in the longitudinal direction, which is the axial direction of the photosensitive drum 102.

[0061] The opening 510a of the housing support member 510 is provided at a position facing the surface (rear surface of the substrate 502) opposite to the mounting surface (front surface of the substrate 502) on which the LEDs 503 are mounted of the substrate 502.

[0062] In this manner, the housing support member 510 is provided over the longitudinal direction, which is the axial direction of the photosensitive drum 102, and has an opening 510a at a position facing the rear surface of the substrate 502. As a result, the airflow sent from the duct unit 606 is blown onto the rear surface of the substrate 502 through the opening 510a of the housing support member 510. The housing support member 510 of the exposure head 104 forms a duct (closed space) that circulates the airflow blown onto the rear surface of the substrate 502 through the opening 510a in the longitudinal direction of the substrate 502, i.e., forms part of a duct that cools the exposure head 104.

[0063] As described above, the exposure head 104 is configured as an integrated head unit by the substrate 502 having the LEDs 503, the lens array 506 consisting of a plurality of lenses, the housing 505, and the housing support member 510.

[0064] (Exposure head positioning member) Next, the positioning of the exposure head 104 in the axial direction of the photosensitive drum 102 by the positioning member 250 will be described with reference to FIGS.

[0065] Fig. 8 is a perspective view of the positioning member 250 after it has been attached, and Fig. 9 is a perspective view of the positioning member before it is attached. Fig. 10 is a perspective view showing the shape of the positioning member 250.

[0066] As shown in Fig. 8, a positioning member 250 for positioning the exposure head 104 with respect to the image forming apparatus 100 is attached to the front side of the exposure head 104. As shown in Fig. 9, a biasing portion 605d, a round hole portion 605e, a square hole portion 605f, and a claw engagement portion 605g are provided on the front side of the cartridge tray 605.

[0067] As shown in FIG. 10, the lower surface of the positioning member 250 is provided with a restricting portion 250a, a biasing portion 250b, a cross-shaped protrusion 250c, an I-shaped protrusion 250d, and a claw portion 250e.

[0068] The outer diameter of the cross-shaped protrusion 250c is approximately equal to the inner diameter of the round hole 605e, and the left-right length of the I-shaped protrusion 250d is approximately equal to the left-right length of the square hole 605f. The protrusions 250c, 250d fit into the holes 605e, 605f, respectively, to determine the position of the positioning member 250 in the front-rear and left-right directions.

[0069] Furthermore, the claw portion 250e has a barbed shape, and the barbed shape is caught by the claw engagement portion 605g, thereby determining the position of the positioning member 250 in the up-down direction.

[0070] The restricting portion 250a has a first contact surface 250a1 that contacts one side of the positioning pin 508 in the axial direction, and a second contact surface 250a2 that contacts the other side of the positioning pin 508 in the axial direction. The first contact surface 250a1 and the second contact surface 250a2 face each other in the axial direction. The restricting portion 250a has a concave shape that opens on the right side in the left-right direction, and the notch width in the front-rear direction of the concave shape and the outer diameter of the positioning pin 508 are configured to be approximately equal. The restricting portion 250a and the positioning pin 508 are fitted together, whereby the exposure head 104 is positioned relative to the positioning member 250 in the axial direction of the photosensitive drum 102.

[0071] In this manner, the position of the exposure head 104 in the axial direction of the photosensitive drum 102 can be precisely determined by the positioning member 250 that is attached after the exposure head 104 is mounted.

[0072] In this embodiment, backlash is eliminated by the urging portion 250b and the urging portion 605d. The urging portion 250b extends rightward from the positioning member 250 in the left-right direction, and has a thin wall shape in the axial direction of the photosensitive drum 102, so that the urging portion 250b is easily elastically deformed in the axial direction of the photosensitive drum 102. On the other hand, the urging portion 605d is shaped to protrude from the upper surface of the cartridge tray 605, and is configured in a shape having rigidity such that it does not deform in the axial direction of the photosensitive drum 102. The dimensional relationship is such that the tip of the urging portion 250b interferes with (comes into contact with) the urging portion 605d when the positioning member 250 is attached to the cartridge tray 605. When the front surface of the tip of the urging portion 250b comes into contact with the back surface of the urging portion 605d, the urging portion 250b elastically deforms in the rear direction, and the reaction force urges the positioning member 250 in the rear direction, i.e., from one side to the other side in the axial direction of the photosensitive drum 102.

[0073] By configuring the positioning member 250 to be biased in the axial direction of the photosensitive drum 102, it is possible to achieve highly accurate positioning of the exposure head 104 that is less susceptible to the effects of repeated attachment and detachment operations of the exposure head 104, and it is possible to achieve even more precise positioning.

[0074] (Movement mechanism) The movement mechanism of the exposure head 104 is composed of a lifting duct 609, a rotating arm 610, and a link member (not shown). In this embodiment, the movement mechanism has the function of moving not only the exposure head 104 (exposure unit 500) but also the development unit 600 to the development position or a retracted position retracted from the development position. The configuration of the movement mechanism is an example and is not limited to this.

[0075] A moving mechanism including a lift duct 609 and a rotating arm 610 will be described with reference to Figures 13 and 14. Figure 13 is a perspective view of the cartridge tray from below. Figure 14 is a front cross-sectional view of the exposure head centered on the exposure head, taken along the line indicated by the arrow XX in Figure 13.

[0076] The lifting duct 609 is an exposure support member that detachably supports the exposure head 104 , and is provided in the main body of the image forming apparatus 100 together with the cartridge tray 605 .

[0077] The lifting duct 609 is provided in the center of the tray corresponding to a position between a developing support portion supporting the developing unit 600 of the cartridge tray 605 and a drum support portion supporting the drum unit 601. The lifting duct 609 is provided in the center of the tray of the cartridge tray 605 so as to be movable between an exposure position where the photosensitive drum 102 is exposed and a retracted position retracted from the exposure position. The lifting duct 609 is supported from below at both ends in the longitudinal direction by a rotating arm 610. The lifting duct 609 is moved by the rotating arm 610 together with the exposure head 104 in a direction perpendicular to the axial direction of the photosensitive drum 102 (movement direction). The lifting duct 609 is moved to the exposure position or the retracted position by the rotation of the rotating arm 610.

[0078] The lifting duct 609 has a longitudinal shape extending in the front-rear direction (the axial direction of the photosensitive drum) like the exposure head 104 so as to be able to support the entire exposure head 104, and has a shape with openings at the top and bottom in the center. The lifting duct 609 forms a duct with one opening (not shown) communicating with the opening 510a of the exposure head 104 and the other opening 609a (see FIG. 13) communicating with the opening 606a (see FIG. 12) of the duct unit 606. The lifting duct 609 supports the exposure head 104, and at the same time forms part of a duct (closed space) that communicates between the exposure head 104 and the duct unit 606 to form a flow path for the airflow that cools the exposure head 104.

[0079] The lift duct 609 is formed in a hollow shape with openings at the top and bottom, and does not have any openings at positions facing the developing unit 600 and the drum unit 601. The lift duct 609 constitutes an exposure duct that communicates between the exposure head 104 and the duct unit 606 and forms a space through which air for cooling the exposure head 104 circulates.

[0080] Therefore, the lift duct 609 allows the airflow from the duct unit 606 to flow through the upper and lower openings to the rear surface of the substrate 502 of the exposure head 104. Therefore, the lift duct 609 can allow the airflow from the duct unit 606 to flow to the rear surface of the substrate 502 of the exposure head 104 without leaking to the adjacent developing unit 600 or drum unit 601 side, thereby reducing toner scattering inside the device.

[0081] Further, at both ends in the longitudinal direction of the lifting duct 609, a rotating arm 610 is disposed for moving the exposure head 104 between an exposure position close to the photosensitive drum 102 and a retracted position retracted from the exposure position. The rotating arm 610 is rotatably provided on the developing unit side of the cartridge tray 605. One end of the rotating arm 610 in the left-right direction perpendicular to the axial direction of the photosensitive drum 102 is supported so as to be rotatable about an axis parallel to the axial direction. The other end of the rotating arm 610 in the left-right direction supports both ends of an area (range Lm in FIG. 13) outside the opening of the lifting duct 609 in the axial direction. The rotating arm 610 is configured to be linked with the opening and closing of the inner door 120 by a link member not shown.

[0082] 13, the range of the opening forming the duct is indicated as La, and the range of the arrangement of the rotating arm 610 is indicated as Lm. The range La of the opening of the lifting / lowering duct 609 is provided within the range Lm of the arrangement of the rotating arm 610.

[0083] It should be noted that range Lc in FIG. 13 is the area in which the FFC connector 504 of the exposure head 104 is provided, and is outside the duct area indicated by range La in FIG. 13, and is provided between the duct area and the area indicated by one of ranges Lm in FIG. 13.

[0084] Moreover, the area La forming the duct includes most of the board 502 on which the LEDs 503 are mounted, and by blowing airflow onto this area La, it is possible to sufficiently cool the exposure head 104. The area Lc is the mounting portion of the FFC connector 504 of the signal line that transmits the drive signal to the board 502 on which the LEDs 503 are mounted. No opening that forms a duct is provided in the area Lc, but as described above, the area La is configured to provide necessary and sufficient cooling.

[0085] As a result, air taken in from outside the apparatus by the duct unit 606 passes through the lift duct 609 and is blown from the opening 510a of the exposure head 104 to the rear surface of the substrate 502. In addition, the airflow blown from the opening 510a of the exposure head 104 to the rear surface of the substrate 502 is exhausted to the outside of the apparatus by the duct unit 606 through the lift duct 609.

[0086] (Duct unit) Image forming apparatus 100 also includes a detachable duct unit 606. The duct unit 606 will be described with reference to Figures 11 and 12. Figure 11 is a cross-sectional view of the image forming apparatus taken along the line AA in Figure 1. Figure 12 is a perspective view of the duct unit as viewed from above.

[0087] The duct unit 606 is an exposure / cooling unit that communicates with an opening 609 a formed by the cartridge tray 605 and the lift duct 609 and cools the exposure head 104 by airflow through the lift duct 609 .

[0088] The duct unit 606 has an exhaust duct 612 that communicates with the lift duct 609 and forms a space for circulating the air introduced from the lift duct 609. An opening 606a that communicates with the lift duct 609 and introduces air from the lift duct 609 is provided for each exposure head on the upper surface of the exhaust duct 612. A fan 608 that generates an air current is provided in the exhaust duct 612.

[0089] The duct unit 606 has an intake duct 611 that communicates with the lift duct 609 and forms a space for circulating air to be introduced into the lift duct 609. An opening 606a that communicates with the lift duct 609 and introduces air into the lift duct 609 is provided for each exposure head on the upper surface of the intake duct 611. A fan 607 that generates an air current is provided in the intake duct 611.

[0090] The duct unit 606 is integrally provided with fans 607 and 608, an intake duct 611, and an exhaust duct 612, and is detachably mounted to the main body of the image forming apparatus 100 directly below the cartridge tray 605.

[0091] Each opening 606a of the duct unit 606 is provided at a position facing an opening 609a of the lifting duct 609 for each exposure head, and is connected to the opening 609a to communicate with the exposure head 104, forming a closed space.

[0092] (Exposure head cooling structure) Here, the cooling configuration of the exposure head will be described with reference to Figures 11 to 14. In Figure 11, the flow of air for cooling the exposure head is indicated by a dashed line, and the air flow indicated by the dashed line is also referred to as exposure cooling air flow.

[0093] The exposure head 104 dissipates heat according to the amount of light emitted by the LEDs 503, and is located close to a developing device that uses toner that is sensitive to heat, so a cooling means is necessary. In particular, when the image formation process is repeated frequently, i.e., when the device is used in a highly productive device, or when high-density images are continuously output, the light emission time is long and the amount of light emitted is large. Therefore, the amount of heat generated by the LEDs 503 and the circuit on the board 502 on which they are mounted also becomes large.

[0094] As a countermeasure against this, for example, the housing 505 of the exposure head 104 is used as a heat sink, so that the exposure head 104 is configured to easily dissipate heat and to be less likely to accumulate heat. However, even in such a case, it is considered that the exposure head 104 cannot be cooled in time, and heat accumulation progresses, and the amount of heat dissipated to the surroundings increases. As a result, the toner around the development unit 600 and part of the circulating toner inside the development unit may fuse together, leading to image defects.

[0095] Even if a configuration for cooling the developing unit 600 is provided, it is easily assumed that the heat stored due to the light emission of the LED 503 will prevail in the area close to the exposure head 104. Therefore, it is desirable to provide a cooling configuration for the exposure head 104 (exposure cooling airflow) to suppress the amount of heat dissipated around the exposure head 104.

[0096] The image forming apparatus 100 has an exposure head 104, a lifting duct 609, a cartridge tray 605, and a duct unit 606. The exposure head 104 is attached to the lifting duct 609 arranged in the image forming apparatus 100, and is integrated with the lifting duct 609. By attaching the exposure head 104 to the lifting duct 609, an opening 510a (see FIG. 15) of a housing support member 510 of the exposure head 104 communicates with one opening 609a (see FIG. 13) of the lifting duct 609. The lifting duct 609 forms a duct that communicates the exposure head 104 and the duct unit 606. The duct unit 606 is attached to the image forming apparatus 100 directly below the cartridge tray 605. In other words, the duct unit 606 is provided on the opposite side of the exposure head 104 from the photosensitive drum 102. When the duct unit 606 is attached to the image forming apparatus 100, an opening 606a (see FIG. 12) of the duct unit 606 communicates with the other opening 609a (see FIG. 13) of the lift duct 609.

[0097] In this way, the housing support member 510 of the exposure head 104, the lift duct 609, the cartridge tray 605, and the duct unit 606 form a cooling duct, which is a single continuous closed space. Each exposure head 104 is cooled by an exposure cooling airflow (indicated by a broken line in FIG. 11 ) that flows through the single closed space formed by the housing support member 510, the lift duct 609, the cartridge tray 605, and the duct unit 606.

[0098] 11 and 12, fan 607 disposed toward the front of the apparatus functions as an intake fan that takes in air (fresh air) from outside the apparatus into duct unit 606. Fan 608 disposed toward the rear of the apparatus functions as an exhaust fan that exhausts air inside duct unit 606 to the outside of the apparatus.

[0099] In the exposure cooling air flow indicated by the dashed line in Fig. 11, when the fans 607 and 608 rotate, air from outside the apparatus is introduced from the intake port 611a through louvers (not shown) provided on the exterior cover of the image forming apparatus. The air introduced from the intake port 611a is exhausted from each opening 606a of the intake duct 611 through the intake duct 611. The air exhausted from each opening 606a is blown onto the exposure head 104 through the lifting duct 609. The air blown onto the exposure head 104 through the lifting duct 609 is circulated from the front side to the rear side of the apparatus along the axial direction of the photosensitive drum 102, and is introduced into the exhaust duct 612 from each opening 606a of the exhaust duct 612 through the lifting duct 609. The air introduced into the exhaust duct 612 from each opening 606a is exhausted to the outside of the apparatus from an exhaust port 612a of the exhaust duct 612 through a louver (not shown) provided on the exterior cover.

[0100] The fans 607 and 608 in the duct unit 606 are controlled based on a temperature sensor (not shown) arranged on the substrate 502 for each color. As a result, the fans do not rotate all the time, but start rotating when the temperature detected by the temperature sensor reaches a predetermined threshold value. In this way, the operation of the exposure cooling flow by the fans is minimized, and the air volume is also kept to a minimum, thereby reducing the possibility of toner scattering inside the device from the viewpoint of control.

[0101] (Method of fixing the housing support member) Next, a method of fixing the housing 505 and the housing support member 510 in the exposure head 104 will be described with reference to Figs. 15 to 17. Fig. 15 is a perspective view of the exposure head according to the first embodiment as seen from below, showing a state in which the housing support member 510 is fixed to the housing 505. Fig. 16 is a perspective view showing one of the connecting portions between the housing and the housing support member according to the first embodiment. Fig. 17 is a perspective view showing the other connecting portion between the housing and the housing support member.

[0102] The housing 505 and the housing support member 510 are fixed at one longitudinal end by an adhesive 511, which is an example of a first connecting member, and at the other longitudinal end by an adhesive 512, which is an example of a second connecting member.

[0103] Incidentally, the image forming apparatus 100 in this embodiment has a configuration including a plurality of photosensitive drums 102 and a plurality of exposure heads 104, but the adhesive 511 as the first connecting member and the adhesive 512 as the second connecting member are common to the plurality of exposure heads 104.

[0104] The exposure head 104 is configured to be mounted in the apparatus by engaging the housing support member 510 with the lift duct 609, and to be removed from the apparatus by disengaging the housing support member 510 from the lift duct 609. For this reason, in the exposure head 104, the housing 505 and the housing support member 510 need to be fixed together to ensure strength.

[0105] In addition, the substrate 502 held by the housing 505 generates heat in the exposure head 104, and the temperature of the entire exposure head 104 rises. The housing 505 is a metallic member made of metal, so that the housing 505 itself can also be used as a heat sink, making it easier for the exposure head 104 to dissipate heat and less likely to accumulate heat. On the other hand, the housing support member 510 is a resin member molded from resin, so that it can be used as an engagement portion with the lift duct 609 and as a part of the cooling mechanism. In other words, the housing 505 and the housing support member 510 have different linear expansion coefficients, and a difference occurs in thermal expansion when the temperature rises. Specifically, the resin housing support member 510 has a larger linear expansion coefficient than the metal housing 505. Therefore, due to the difference in thermal expansion when the temperature rises, the resin housing support member 510 is more deformed than the metal housing 505. The deformation of the housing 505 and the housing support member 510 due to this difference in thermal expansion induces deformation of the substrate 502 and the lens array 506, etc., and may affect the optical characteristics of the exposure head 104.

[0106] Therefore, in this embodiment, adhesives having different hardness are used for adhesives 511 and 512 to fix housing 505 and housing support member 510. That is, adhesive 511 that fixes one end in the longitudinal direction is used with an adhesive having a higher hardness than adhesive 512 that fixes the other end in the longitudinal direction to fix housing 505 and housing support member 510.

[0107] Adhesives 511 and 512 are filled between housing 505 and housing support member 510 to fix housing 505 and housing support member 510. For example, adhesive is applied so as to fill between the flat surface of housing 505 and a portion of housing support member 510 facing the flat surface of housing 505, thereby fixing housing 505 and housing support member 510.

[0108] FIG. 16 shows a connection between housing 505 and housing support member 510 using adhesive 511, and FIG. 17 shows a connection between housing 505 and housing support member 510 using adhesive 512.

[0109] 16 uses an adhesive with a higher hardness than adhesive 512 shown in Fig. 17, and has the function of securing strength by fixing housing 505 and housing support member 510 at one end in the longitudinal direction. In this embodiment, for example, Chemiseal U-1542J, an ultraviolet curing resin made by Chemitech Corporation, is used as adhesive 511, and the hardness of the cured adhesive is 80 (test method: JIS K 7215 Shore D) and the tensile strength is 16 MPa (test method: JIS K 6251 JIS No. 2 dumbbell).

[0110] 16, adhesive 512 has a function of reducing deformation at the other end in the longitudinal direction due to the difference in thermal expansion between housing 505 and housing support member 510. In this embodiment, adhesive 512 is, for example, 3017F made by ThreeBond Co., Ltd., and the hardness of the cured adhesive is 58 / 59 (test method: 3TS-215-01), and the tensile strength is 3.4 / 3.2 (test method: 3TS-301-13, adhesive: ZnDc / glass).

[0111] The adhesive strength of the adhesive 511 and the adhesive 512 is increased by applying them so as to bridge the objects to be fixed to each other, rather than applying them to a flat surface. Therefore, in this embodiment, as shown in FIG. 16, the adhesive 511 filled between the housing 505 and the housing support member 510 at one end in the longitudinal direction is applied so as to bridge between the housing support member 510 and the first positioning pin 508 along the flat surface of the housing 505. In other words, the adhesive 511 that fixes the housing 505 and the housing support member 510 at one end in the longitudinal direction is applied so as to fill the gap between the housing support member 510 and the first positioning pin 508. Also, as shown in FIG. 17, the adhesive 512 filled between the housing 505 and the housing support member 510 at the other end in the longitudinal direction is applied so as to bridge between the housing support member 510 and the second positioning pin 509 along the flat surface of the housing 505. In other words, adhesive 512 that fixes housing 505 and housing support member 510 at the other end in the longitudinal direction is applied so as to fill the gap between housing support member 510 and second positioning pin 509. In this way, applying the adhesive so as to bridge the objects to be fixed together increases the adhesive strength.

[0112] In this embodiment, a high hardness adhesive is used for adhesive 511 that fixes one end in the longitudinal direction, and a low hardness adhesive is used for adhesive 512 that fixes the other end in the longitudinal direction. This is because the positioning of exposure head 104 on the main body is based on positioning pin 508 on the front side of the device.

[0113] Specifically, as described above, the image forming apparatus 100 has a positioning member 250 for positioning the exposure head 104 relative to the image forming apparatus 100. The positioning member 250 is attached to one end side in the longitudinal direction of the exposure head 104. The adhesive 511 that fixes the one end in the longitudinal direction uses an adhesive having a higher hardness than the adhesive 512 that fixes the other end in the longitudinal direction, and the adhesive 511 that has a higher hardness than the adhesive 512 is used on the same side of the image forming apparatus 100 as the positioning member 250.

[0114] That is, one end in the longitudinal direction of the housing 505 and the housing support member 510, which is the positioning side (front side) of the image forming apparatus 100, is fixed with adhesive 511 having a harderness than adhesive 512. This makes it possible to secure strength by fixing the housing 505 and the housing support member 510 on the front side, which is the positioning side of the image forming apparatus, and makes it possible to bring the positioning of the exposure head 104 and the elongation standard due to thermal expansion closer together.

[0115] The adhesive is applied with a dispenser or similar device to precisely apply the liquid. The outlet nozzle and needle is typically SNA-12G from Musashi Engineering Co., Ltd.

[0116] Furthermore, the above-mentioned method of fixing the housing 505 of the exposure head 104 to the housing support member 510 is the same for each color (exposure heads 104Y, 104M, 104C, 104K). This makes it possible to suppress deformation due to thermal expansion in the exposure heads 104Y, 104M, 104C, 104K of each color, and therefore makes it possible to effectively suppress color misalignment of each color.

[0117] As described above, the adhesive 511 for fixing one end in the longitudinal direction has a function of securing strength by fixing the housing 505 and the housing support member 510 by using an adhesive having a higher hardness than the adhesive 512 for fixing the other end in the longitudinal direction. On the other hand, the adhesive 512 for fixing the other end in the longitudinal direction has a function of reducing deformation due to thermal expansion of the housing 505 and the housing support member 510 by using an adhesive having a lower hardness than the adhesive 511 for fixing one end in the longitudinal direction. That is, according to this embodiment, it is possible to achieve both the strength required for the assembly and positioning of the exposure head and the reduction of deformation of the substrate and the lens array due to the difference in thermal expansion.

[0118] Example 2 An exposure head according to Example 2 will be described with reference to Fig. 18. Fig. 18 is a perspective view showing one of the connecting parts between the housing and the housing support member according to Example 2. Note that, except for the configuration of the connecting part between the housing and the housing support member in the exposure head, the other configurations are the same as those in the above-mentioned examples, and therefore descriptions thereof will be omitted here. Also, members having the same functions as those in the above-mentioned examples will be given the same reference numerals, and descriptions thereof will be omitted.

[0119] In the above-described embodiment, a configuration in which the first connecting member that fixes one end of the longitudinal direction of the housing 505 and the housing support member 510 in the exposure head 104 is an adhesive 511 is given as an example, but this is not limited to this.

[0120] In this embodiment, the first connecting member that fixes one end in the longitudinal direction of the housing 505 and the housing support member 510 in the exposure head 104 is a screw 513, which is an example of a fastening member that fastens the housing 505 and the housing support member 510. That is, the housing 505 and the housing support member 510 are fixed to each other by the first connecting member that fixes one end in the longitudinal direction and the screw 513, which has a harder hardness than the adhesive 512 that fixes the other end in the longitudinal direction. Here, the screw 513 is illustrated as an example of a fastening member, but the present invention is not limited to this.

[0121] According to this embodiment, one longitudinal end of the housing 505 and the housing support member 510, which is the front side of the image forming apparatus 100, can be fastened with a screw 513, thereby fixing the housing 505 and the housing support member 510 and ensuring their strength.

[0122] In this embodiment as well, one longitudinal end of housing 505 and housing support member 510 is fixed with adhesive 512 having a lower hardness than screws 513, so that deformation due to the difference in thermal expansion between housing 505 and housing support member 510 can be reduced.

[0123] Example 3 An exposure head according to Example 3 will be described with reference to Fig. 19. Fig. 19 is a perspective view showing one of the connecting parts between the housing and the housing support member according to Example 3. Note that, except for the configuration of the connecting part between the housing and the housing support member in the exposure head, the other configurations are the same as those in the above-mentioned examples, and therefore descriptions thereof will be omitted here. Also, members having the same functions as those in the above-mentioned examples will be given the same reference numerals, and descriptions thereof will be omitted.

[0124] In this embodiment, the first connecting member that fixes one end in the longitudinal direction of the housing 505 and the housing support member 510 in the exposure head 104 is a fitting member 514 that fits into the housing 505. That is, the housing 505 and the housing support member 510 are fixed to each other by the first connecting member that fixes one end in the longitudinal direction and the fitting member 514 that has a harder hardness than the adhesive 512 that fixes the other end in the longitudinal direction.

[0125] As an example of the fitting member, a claw-shaped fitting member 514 is provided. The fitting member 514 is provided at one end in the longitudinal direction of the housing support member 510. The fitting member 514 is a claw-shaped member that protrudes toward one side (the left side in this case) of the left and right directions perpendicular to the axial direction (front-rear direction) of the photosensitive drum, and is elongated in the axial direction of the photosensitive drum. The fitting member 514 has a protrusion 514a that protrudes toward the housing 505 in the left-right direction as a claw-shaped part. The protrusion 514a of the fitting member 514 fits into a hole 515 provided in the housing 505. The hole 515 of the housing 505 is provided at a position facing the fitting member 514 of the housing support member 510, and is an elongated hole that is elongated in the axial direction of the photosensitive drum 102, similar to the protrusion 514a that is the claw-shaped part of the fitting member 514.

[0126] The housing support member 510 is fixed to the housing 505 by inserting the protrusion 514 a of the fitting member 514 of the housing support member 510 into the hole 515 of the housing 505 .

[0127] Specifically, when housing support member 510 is attached to housing 505 from below, fitting member 514 of housing support member 510 bends and enters the inside of housing 505. When housing support member 510 is further attached to housing 505, protrusion 514a of fitting member 514 reaches hole 515 of housing 505, and is positioned and fixed in hole 515 while releasing the bending.

[0128] The housing 505 and the housing support member 510 are secured in the longitudinal direction by the engagement of the projection 514a of the engaging member 514 and the hole 515, thereby ensuring their strength. The housing 505 and the housing support member 510 are not secured in the lateral direction (left-right direction) perpendicular to the longitudinal direction (front-rear direction) and in the vertical direction (up-down direction) by the projection 514a of the engaging member 514 and the hole 515.

[0129] According to this embodiment, one longitudinal end of the housing 505 and the housing support member 510, which is the front side of the image forming apparatus 100, is fixed with an engaging member 514, whereby the housing 505 and the housing support member 510 can be fixed and their strength can be ensured.

[0130] In this embodiment, one end of the longitudinal direction of the housing 505 and the housing support member 510 is fixed with the adhesive 512 having a lower hardness than the fitting member 514, so that deformation due to the difference in thermal expansion between the housing 505 and the housing support member 510 can be reduced. [Explanation of symbols]

[0131] 100 ... Image forming device 101 ... Image forming section 102 ... Photosensitive drum (photoconductor) 104 ... exposure head (exposure device) 250 ... Positioning member 500 ... Exposure unit (exposure device) 502 ... Substrate 503 ... LED (light emitting element) 504...FFC connector 505 ... Enclosure 506 ... Lens array 508, 509 ... Positioning pin (fixing member) 510 ... Housing support member 510a...Aperture 511 ... adhesive (first connecting member) 512 ... adhesive (second connecting member) 513 ... Screw (first connecting member) 514 ... Fitting member (first connecting member) 514a...protrusion 515 ... Hole 600 ...Developing unit 601 ... Drum unit 605 ... Cartridge tray 606 ... Duct unit 606a...Aperture 607,608 … Fans 609 … Lifting duct 609a...Aperture 610 ... Rotating arm 611 ... Intake duct 611a … Intake port 612 ... Exhaust duct 612a …Exhaust port 639 ... LED chip

Claims

1. An exposure device having an elongated shape extending in an axial direction of a photoconductor and exposing the photoconductor, A substrate on which a plurality of light emitting elements are arranged; a lens array that focuses the light emitted from the light-emitting element onto the photosensitive member; a housing for holding the substrate and the lens array; a housing support member that supports the housing in a longitudinal direction; a first connecting member that fixes the housing and the housing support member at one end in a longitudinal direction; a second connecting member that fixes the housing and the housing support member at the other end in the longitudinal direction, 13. An exposure apparatus, wherein the first connecting member has a harder hardness than the second connecting member.

2. 2. The exposure apparatus according to claim 1, wherein the first connecting member and the second connecting member are adhesive.

3. 3. The exposure apparatus according to claim 2, wherein the adhesive is filled between the housing and the housing support member to fix the housing and the housing support member together.

4. a first fixing member fixed to the housing on one side of the lens array in the axial direction of the photoconductor; a second fixing member fixed to the housing on the other side of the lens array in the axial direction of the photoconductor; The adhesive filled between the housing and the housing support member at one end in the longitudinal direction is applied along a plane of the housing so as to bridge the adhesive to the first fixing member; 3. The exposure apparatus according to claim 2, wherein the adhesive filled between the housing and the housing support member at the other longitudinal end is applied so as to bridge the second fixing member along a plane of the housing.

5. the first fixing member is a first positioning pin for keeping a constant distance between the photoconductor and the exposure device; 5. The exposure device according to claim 4, wherein the second fixing member is a second positioning pin for keeping a constant distance between the photosensitive member and the exposure device.

6. 2. The exposure apparatus according to claim 1, wherein the first connecting member is a fastening member that fastens the housing and the housing support member together.

7. 2. The exposure apparatus according to claim 1, wherein the first connecting member is a fitting member that is provided on the housing support member and fits into the housing.

8. The exposure device according to claim 7, characterized in that the fitting member is a claw-shaped member provided on the housing support member, protruding in one direction perpendicular to the axial direction of the photosensitive body, and elongated in the axial direction of the photosensitive body, and is fitted into a hole provided in the housing.

9. 2. The exposure apparatus according to claim 1, wherein the housing support member has a linear expansion coefficient larger than that of the housing.

10. 2. The exposure apparatus according to claim 1, wherein the housing is a member made of metal, and the housing support member is a member made of resin.

11. 2. The exposure apparatus according to claim 1, wherein the housing support member has an opening at a position facing the back surface of the substrate opposite the front surface on which the light-emitting element is mounted, and forms a duct that circulates the airflow blown onto the back surface of the substrate through the opening in the longitudinal direction of the substrate.

12. a photoconductor; an exposure head for exposing the photoconductor; and an exposure cooling unit communicating with the exposure head for cooling the exposure head by airflow; 12. An image forming apparatus comprising the exposure device according to claim 1 as the exposure head.

13. a positioning member attached to one end of the exposure head in a longitudinal direction for positioning the exposure head with respect to an image forming apparatus; 13. The image forming apparatus according to claim 12, wherein the first connecting member, which is harder than the second connecting member, is used on the same side of the image forming apparatus as the positioning member.

14. the image forming apparatus includes a plurality of the photoconductors and a plurality of the exposure heads, 13. The image forming apparatus according to claim 12, wherein the first connecting member and the second connecting member are common to a plurality of exposure heads.

Images