Exposure device and image formation device

Abstract

To suppress outflow of air flow from a gap in an exposure device.SOLUTION: An exposure device includes: a substrate in which a plurality of light emitting elements are arrayed along an axial direction of a photoreceptor, the light emitting elements emitting light for exposure of the photoreceptor; a lens array including a plurality of lenses condensing light emitted from the light emitting elements to the photoreceptor; a housing including an opening and holding the substrate and the lens array; a housing support member provided integrally with the housing so as to cover the opening of the housing and forming a space between the housing support member and the housing for air circulation; and a sealing member sealing a gap between the housing and the housing support member facing each other on one side and the other side of the substrate in an optical axis direction along an optical axis of the lenses and a direction orthogonal to the axial direction.SELECTED DRAWING: Figure 16

Description

[Technical Field]

[0001] The present invention relates to an exposure device that exposes a photosensitive member to light and an image forming apparatus that includes the exposure device. [Background technology]

[0002] 2. Description of the Related Art Conventionally, as an exposure device used in an electrophotographic image forming apparatus, an exposure device of an LED array type in which a plurality of light emitting elements are arranged along the axial direction of a photosensitive member is known.

[0003] This type of exposure device is known to dissipate heat according to the length of time the light-emitting element emits light and the amount of light emitted. Furthermore, the exposure device is located close to a developing device that develops the latent image formed on the photosensitive member with toner. Therefore, a technique for suppressing the temperature rise of the exposure device is known to suppress the effect of heat from the exposure device on the toner.

[0004] In Patent Document 1, a duct for circulating airflow through the exposure device is formed by a housing that holds a substrate on which light-emitting elements are mounted and a lens array, and a housing support member that supports the housing, and the airflow cools the substrate and prevents the temperature of the exposure device from rising. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2023-132358 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the conventional technology, there is a gap between the housing that constitutes the duct in the exposure device and the housing support member due to the component configuration, and there is a risk that the airflow mentioned above will escape from this gap. In this case, toner and fine dust particles near the lens array may fly off and adhere to the surface of the lens array, causing image defects.

[0007] An object of the present invention is to suppress the outflow of air currents from gaps in an exposure device. [Means for solving the problem]

[0008] A typical configuration of the present invention is characterized by comprising a substrate on which a plurality of light-emitting elements that emit light to expose a photosensitive member are arranged along the axial direction of the photosensitive member, a lens array having a plurality of lenses that focus the light emitted from the light-emitting elements onto the photosensitive member, a housing that includes an opening and holds the substrate and the lens array, a housing support member that is integrally formed with the housing so as to cover the opening of the housing and forms a space for air to circulate between the housing and the housing support member, and a sealing member that seals the gap between the housing and the housing support member that face each other on one side and the other side of the substrate in the optical axis direction along the optical axis of the lens and in a direction perpendicular to the axial direction. [Effects of the Invention]

[0009] According to the present invention, it is possible to prevent air currents from leaking out from gaps in the exposure device. [Brief explanation of the drawings]

[0010] [Figure 1] Perspective view of an image forming apparatus [Figure 2] Schematic cross-sectional view of an image forming apparatus [Figure 3] Schematic cross-sectional view of an image forming apparatus [Figure 4] (a) and (b) are perspective views showing the configuration of the drum unit and the developing unit and its surroundings. [Figure 5] Schematic cross-sectional view of the exposure head [Figure 6] A perspective view of the exposure head seen from above [Figure 7] A perspective view of the exposure head seen from below [Figure 8] (a), (b), and (c) are diagrams showing the substrate of the exposure head, and (d) and (e) are diagrams showing the lens array. [Figure 9]FIG. 1 is a perspective view showing a cartridge tray, an inner door in a closed state, and an exposure head in an exposure position. [Figure 10] 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 11] Cross-sectional view along arrow AA in Figure 2 [Figure 12] Perspective view of the duct unit [Figure 13] Perspective view of the cartridge tray and lifting duct from below [Figure 14] Cross-sectional view taken along arrow XX in Figure 13 [Figure 15] FIG. 1 is a diagram showing the longitudinal lengths of the sheet and openings of the exposure head according to the first embodiment; [Figure 16] 1 is a cross-sectional view of an exposure head according to a first embodiment; [Figure 17] FIG. 1 is a perspective view of an exposure head according to a first embodiment; [Figure 18] 1 is a perspective view of an exposure head, a lifting duct, and a duct unit according to a first embodiment; [Figure 19] 10 is a cross-sectional view of an exposure head according to a second embodiment. [Figure 20] 10 is a cross-sectional view of an exposure head according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the dimensions, materials, shapes, and relative positions of the components described below are merely examples and are not intended to limit the scope of the present invention.

[0012] Example 1 (Image forming device) First, a schematic configuration of an image forming apparatus 100 will be described with reference to Figures 1, 2, and 3. Figure 1 is a perspective view of the image forming apparatus 100. Figures 2 and 3 are schematic cross-sectional views of the image forming apparatus in Figure 1. The image forming apparatus 100 shown in Figures 1 to 3 is a copier equipped with a reading device, but embodiments may also be other image forming apparatuses, such as a printer that does not have a reading device. Furthermore, embodiments are not limited to color image forming apparatuses equipped with multiple photosensitive drums 2 as shown in Figures 2 and 3, but may also be color image forming apparatuses equipped with one photosensitive drum 2 or image forming apparatuses that form monochrome images.

[0013] The image forming apparatus 100 shown in Figures 2 and 3 includes four image forming units 1Y, 1M, 1C, and 1K (hereinafter collectively referred to simply as "image forming units 1") that form toner images of yellow, magenta, cyan, and black, respectively.

[0014] The image forming units 1Y, 1M, 1C, and 1K each include a photosensitive drum 2Y, 2M, 2C, or 2K (hereinafter collectively referred to as "photosensitive drum 2"), which is an example of a photosensitive body (image carrier). These photosensitive drums are arranged at a distance from each other. The photosensitive drums may be photosensitive belts.

[0015] The image forming units 1Y, 1M, 1C, and 1K are provided with charging rollers 3Y, 3M, 3C, and 3K (hereinafter also collectively referred to simply as "charging rollers 3") as charging means for charging the photosensitive drums 2Y, 2M, 2C, and 2K, respectively.

[0016] The image forming units 1Y, 1M, 1C, and 1K are equipped with exposure heads 4Y, 4M, 4C, and 4K (hereinafter also collectively referred to simply as "exposure heads 4") as exposure devices (exposure means) that expose the photosensitive drums 2Y, 2M, 2C, and 2K to light.

[0017] Furthermore, the image forming units 1Y, 1M, 1C, and 1K are equipped with developing units 24Y, 24M, 24C, and 24K (hereinafter collectively referred to as "developing units 24") as developing means that develop the electrostatic latent images on the photosensitive drums 2 with toner and develop toner images of the respective colors on the photosensitive drums 2. The letters Y, M, C, and K attached to the reference numerals indicate the colors of the toner.

[0018] The image forming apparatus 100 shown in Figures 2 and 3 is an image forming apparatus that employs a so-called "bottom exposure method" in which the photosensitive drum 2 is exposed from below. In the image forming apparatus 100 that employs the bottom exposure method, an exposure head 4 is disposed below the photosensitive drum 2. The following description will be given on the assumption that the image forming apparatus employs the bottom exposure method. Note that, although not shown, an embodiment may also employ an image forming apparatus that employs the "top exposure method" in which the photosensitive drum is exposed from above.

[0019] The image forming apparatus 100 includes an intermediate transfer belt 9 onto which the toner image formed on the photosensitive drum 2 is transferred, and primary transfer rollers 6 (Y, M, C, K) that sequentially transfer the toner image formed on the photosensitive drum 2 onto the intermediate transfer belt 9. The intermediate transfer belt 9 is disposed above the image forming unit 1. Note that, in addition to the intermediate transfer method using the intermediate transfer belt 9, a direct transfer method in which an image is directly transferred from the photosensitive drum 2 to paper may also be used.

[0020] The image forming apparatus 100 also includes a secondary transfer roller 16 as a transfer means for transferring the toner image on the intermediate transfer belt 9 onto the recording paper P transported from the feed unit 11, and a fuser 19 as a fixing means for fixing the secondarily transferred image onto the recording paper P. The secondary transfer roller 16 abuts against the belt drive roller 10 of the intermediate transfer belt 9 with a predetermined pressing force via the intermediate transfer belt 9, and forms a secondary transfer section T2 together with the intermediate transfer belt 9.

[0021] Furthermore, toner bottles 22Y, 22M, 22C, and 22K (hereinafter collectively referred to as "toner bottles 22") that contain replenishment toner of each color are units that can be detached and replaced with respect to image forming apparatus 100. Toner bottles 22 are disposed above intermediate transfer belt 9. Toner bottles 22 replenish the appropriate amount of toner at the appropriate time to each of the development units provided in the four image forming units by a toner replenishment mechanism (not shown) from the corresponding toner bottles.

[0022] The image forming apparatus 100 also includes a feeding unit 11 that feeds recording paper P. The feeding unit 11 has sheet cassettes 12a and 12b, feeding rollers 13a and 13b, and registration rollers 15. The sheet cassettes 12a and 12b are disposed below the image forming unit 1. The recording paper P stored in the sheet cassettes 12a and 12b is fed one sheet at a time by the feeding rollers 13a and 13b, and is transported to the secondary transfer unit T2 at a predetermined timing by the registration rollers 15.

[0023] The image forming apparatus 100 also includes a detachable duct unit 60. The duct unit 60 is disposed below the image forming section 1 and above the feeding section 11. The duct unit 60 is an exposure cooling unit that communicates with the exposure head 4 through an elevation duct 69 (described later) and generates an airflow that cools the exposure head 4.

[0024] (Image formation process) Next, a brief description will be given of the image formation process of the image forming apparatus 100. The charging roller 3Y charges the surface of the photosensitive drum 2Y. The exposure head 4Y exposes the surface of the photosensitive drum 2Y charged by the charging roller 3Y. As a result, an electrostatic latent image is formed on the photosensitive drum 2Y. Next, the developing unit 24Y develops the electrostatic latent image formed on the photosensitive drum 2Y with yellow toner. The yellow toner image developed on the surface of the photosensitive drum 2Y is transferred onto the intermediate transfer belt 9 by the primary transfer roller 6Y. Magenta, cyan, and black toner images are formed in a similar image formation process and transferred to the intermediate transfer belt 9 so as to be superimposed on top of each other.

[0025] The toner images of each color transferred onto the intermediate transfer belt 9 are transported by the intermediate transfer belt 9 to a secondary transfer unit T2. The toner images transported to the secondary transfer unit T2 are transferred all at once by a secondary transfer roller 16 onto a recording sheet P transported from a feed unit 11. The recording sheet P onto which the toner images have been transferred is transported to a fuser 19. The fuser 19 fuses the toner images onto the recording sheet P by heat and pressure. The recording sheet P that has been fixed by the fuser 19 is discharged by a discharge roller 20 onto a discharge tray 21 that is located above a toner bottle 22.

[0026] (Drum unit and developing unit) The replaceable drum unit 23 and developing unit 24 in the image forming apparatus 100 of this embodiment will be described as an example.

[0027] Drum units 23Y, 23M, 23C, and 23K (hereinafter collectively referred to as "drum units 23") each equipped with a photosensitive drum 2 are attached to the image forming apparatus 100. The drum unit 23 is a cartridge in which the photosensitive drum 2, a charging roller 3, and a cleaning device (not shown) are integrated, and is removed from the main body of the image forming apparatus 100 and replaced by an operator such as a user or maintenance technician. The drum unit 23 rotatably supports the photosensitive drum 2. Specifically, the photosensitive drum 2 is rotatably supported by a frame of the drum unit 23. The drum unit 23 may not be equipped with the charging roller 3 or the cleaning device.

[0028] Furthermore, developing units 24Y, 24M, 24C, and 24K (hereinafter collectively referred to as "developing units 24") that are separate from drum unit 23, which is a photosensitive unit, are attached to image forming apparatus 100. Developing unit 24 includes developing sleeves 5Y, 5M, 5C, and 5K (hereinafter collectively referred to as "developing sleeves 5") that serve as developer carriers that carry developer, and screws 7Y, 7M, 7C, and 7K (hereinafter collectively referred to as "screws 7") that supply developer to developing sleeve 5 and agitate the developer. Developing unit 24 is a cartridge in which developing sleeve 5 and screw 7 are integrated, and is removed from the main body of image forming apparatus 100 and replaced by an operator.

[0029] Furthermore, the image forming apparatus 100 is provided with a cartridge tray 30 (30Y, 30M, 30C, 30K) for each image forming unit (see FIGS. 9 and 10). The cartridge tray 30 supports a drum unit 23 and a developing unit 24 for each image forming unit. The drum unit 23 and the developing unit 24 are guided in the axial direction of the photosensitive drum by the cartridge tray 30 for each image forming unit, and are inserted into and removed from the main body of the image forming apparatus 100.

[0030] As shown in FIGS. 4(a) and 4(b), one side of the cartridge tray 30 is attached to a front side plate 100F and the other side is attached to a rear side plate 100B in the axial direction of the photosensitive drum. The front side plate 100F is made of sheet metal and forms part of the housing of the image forming apparatus 100 on the front side of the apparatus body. The rear side plate 100B is made of sheet metal and forms part of the housing of the image forming apparatus 100 on the rear side of the apparatus body. The front side plate 100F and the rear side plate 100B are arranged facing each other on one side and the other side in the axial direction of the photosensitive drum, and a metal beam (not shown) bridges between them. The front side plate 100F, the rear side plate 100B, and the beam (not shown) each form part of the frame (housing) of the image forming apparatus. Here, with respect to the image forming apparatus of this embodiment or its constituent members, the front side or near side is the side from which the drum unit 23 and the developing unit 24 are inserted into and removed from the main body of the image forming apparatus 100.

[0031] The drum unit 23 and the developing unit 24 deteriorate as the image forming process is repeated, so they are in the form of units (cartridges) that can be replaced or detached for maintenance.

[0032] 3 shows the arrangement of the drum unit 23, the developing unit 24, and the exposure head 4 when replacing or removing them. In the image forming apparatus shown in FIG. 3, unlike the image forming apparatus shown in FIG. 2, it can be seen that the developing unit 24 and the exposure head 4 are retracted and separated from the photosensitive drum 2.

[0033] This is because if the developing unit 24 and the exposure head 4 are kept close to the photosensitive drum 2 as shown in FIG. 2, dynamic interference when attaching or detaching the units may damage each unit, or even make it impossible to remove the units.

[0034] For this reason, when the unit is attached or detached, the developing unit 24 and the exposure head 4 are retracted and separated from the photosensitive drum 2 by the moving mechanism as shown in FIG.

[0035] Drum unit 23 and developing unit 24 are inserted and removed from the front side of image forming apparatus 100, and are mounted in predetermined positions (mounting positions) on the main body of image forming apparatus 100.

[0036] The image forming apparatus 100 is equipped with inner doors 102Y, 102M, 102C, and 102K (hereinafter collectively referred to as "inner door 102") that cover the front sides of both the drum unit 23 and the developing unit 24 that are installed in the installation position. The inner door 102 is pivotally supported on the front side of the cartridge tray 30 and is rotatable within a predetermined range relative to the cartridge tray 30. In other words, the inner door 102 is provided so as to be openable and closable relative to the image forming apparatus.

[0037] Furthermore, a front cover 101 that forms the exterior of the device is provided on the front side of the image forming apparatus 100. One end of the front cover 101 is fixed to the front side of the device body of the image forming apparatus 100 by a hinge, and the front cover 101 is rotatable relative to the device body of the image forming apparatus 100 by the hinge. The front cover 101 is provided forward of the inner door 102 in the axial direction of the photosensitive drum. In the closed state shown in FIG. 1, the front cover 101 entirely covers the multiple inner doors 102 that are lined up in the left-right direction, forming the exterior of the front side of the device.

[0038] Therefore, the replacement work of the drum unit 23 and the developing unit 24 is performed by an operator in the following procedure: The operator opens the front cover 101, then opens the inner door 102 as shown in Figures 3(a) and 3(b), and removes the drum unit 23 or the developing unit 24 from the main body of the apparatus. Then, the operator inserts a new drum unit 23 or the developing unit 24, closes the inner door 102, and then closes the front cover 101, thereby completing the replacement work.

[0039] Although not shown, the image forming apparatus 100 according to this embodiment includes a movement mechanism that moves the exposure head 4 to an exposure position or a retracted position (separated position) relative to the photosensitive drum 2. The movement mechanism is provided in the image forming apparatus 100, and moves the exposure head 4 to the exposure position or to a retracted position retracted from the exposure position.

[0040] In this embodiment, the movement mechanism moves the exposure head 4 away from the photosensitive drum 2 in conjunction with the operation of opening the inner door 102, and retracts the exposure head 4 to the retracted position, as shown in Fig. 10. On the other hand, the movement mechanism moves the exposure head 4 in a direction approaching the photosensitive drum 2 in conjunction with the operation of closing the inner door 102, as shown in Fig. 9, and moves the exposure head 4 to the exposure position.

[0041] In this embodiment, the movement mechanism not only moves the exposure head 4 but also moves the developing unit 24 to the development position or a retracted position retracted from the development position. That is, the movement mechanism moves the developing unit 24 in a direction away from the photosensitive drum 2 in conjunction with the operation of opening the inner door 102, thereby retracting the developing unit 24 to the retracted position. On the other hand, the movement mechanism moves the developing unit 24 in a direction approaching the photosensitive drum 2 in conjunction with the operation of closing the inner door 102, thereby moving the developing unit 24 to the development position.

[0042] In the following description, the front panel side of the apparatus body is defined as the front side (near side or front side), and the rear panel side is defined as the rear side (rear side or back side). Furthermore, when the photosensitive drum 2K on which the electrostatic latent image for the black toner image is formed is used as a reference, the side on which the photosensitive drum 2Y on which the electrostatic latent image for the yellow toner image is formed is defined as the left side. When the photosensitive drum 2Y on which the electrostatic latent image for the yellow toner image is formed is used as a reference, the side on which the photosensitive drum 2K on which the electrostatic latent image for the black toner image is formed is defined as the right side. Furthermore, the direction perpendicular to the front-rear and left-right directions defined here, and pointing vertically upward, is defined as the up direction, and the direction perpendicular to the front-rear and left-right directions defined here, and pointing vertically downward is defined as the down direction. The defined front direction F, rear direction B, right direction R, left direction L, up direction U, and down direction D are shown in FIG. 1.

[0043] In addition, the axial direction of the photosensitive drum 2 described below is the direction that coincides with the front-to-rear direction (front-to-rear direction) shown in FIG. 1. The longitudinal direction of the exposure head 4 also coincides with the front-to-rear direction shown in FIG. 1. That is, the axial direction of the photosensitive drum 2 and the longitudinal direction of the exposure head 4 coincide with each other. Furthermore, one side in the axial direction of the photosensitive drum 2 means the front side as defined here, and the other side means the rear side as defined here. One side and the other side in the front-to-rear direction also correspond to the front side and rear side as defined here. One side in the left-to-right direction means the left side as defined here, and the other side means the right side as defined here.

[0044] (Exposure head) Next, the exposure head 4 will be described with reference to Figures 5 to 7. Figure 5 is a schematic cross-sectional view of the exposure head 4 provided in the image forming apparatus of this embodiment. Figure 6 is a perspective view of the exposure head 4 as seen from above. Figure 7 is a perspective view of the exposure head 4 as seen from below.

[0045] Here, one example of an exposure method adopted in an electrophotographic image forming apparatus 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 the photosensitive drum is exposed via an f-θ lens, etc. The "exposure head 4" described in this embodiment is used in an LED exposure method in which the photosensitive drum 2 is exposed using light-emitting elements such as LEDs arranged along the rotation axis direction of the photosensitive drum 2, but is not used in the laser beam scanning exposure method mentioned above.

[0046] 6 and 7, the exposure head 4 has an elongated shape (longitudinal shape) extending in the axial direction of the photosensitive drum 2. As shown in Fig. 5, the exposure head 4 includes a substrate 50, light-emitting elements mounted on the substrate 50, a lens array 52, a housing 54 that holds the substrate 50 and the lens array 52, and a housing support member 55 that supports the housing 54. Here, the exposure head 4 includes LEDs 51 (Light Emitting Diodes) as light-emitting elements that emit light.

[0047] (Substrate and lens array) Here, the substrate 50 and lens array 52 of the exposure head 4 will be described with reference to Fig. 8. First, the substrate 50 will be described. Fig. 8(a) is a schematic perspective view of the substrate 50. Fig. 8(b) shows the arrangement of a plurality of LEDs 51 provided on the substrate 50, and Fig. 8(c) shows an enlarged view of Fig. 8(b).

[0048] (substrate) An LED chip 53 is mounted on the substrate 50. As shown in Fig. 8(a), the LED chip 53 is provided on one surface of the substrate 50, and a long connector 57 is provided on the other surface. The one surface of the substrate 50 here refers to the surface (upper surface, front surface) on which the LED chip 53 is provided. The other surface of the substrate refers to the surface (lower surface, back surface) opposite to the side on which the LED chip 53 is provided.

[0049] The connector 57 is attached to the other surface (bottom surface, back surface) of the substrate 50 so that its longitudinal direction is along the longitudinal direction of the substrate 50. The long connector 57 is provided on the front side of the image forming apparatus 100 (one side in the longitudinal direction of the substrate 50). The substrate 50 is provided with wiring for supplying signals to each LED chip 53. One end of a flexible flat cable (not shown, hereinafter abbreviated as FFC), which is an example of a cable, is connected to the connector 57.

[0050] The control circuit section of the image forming apparatus 100 is provided with a board (not shown) that includes a control section and a connector. The other end of the FFC is connected to the connector. That is, the FFC electrically connects the board (control circuit section) of the device main body with the board 50 of the exposure head 4. A control signal (drive signal) is input to the board 50 of the exposure head 4 from the control circuit section of the device main body of the image forming apparatus 100 via the FFC and connector 57. The control signal is transferred to each LED chip 53 mounted on the board 50. The LED chips 53 are driven (to emit light or turn off) by the control signal input to the board 50.

[0051] The LED chips 53 mounted on the substrate 50 will be described in more detail. As shown in FIGS. 8(b) and 8(c), LED chips 53-1 to 53-29 (29 chips) each having a plurality of LEDs 51 (an example of a light-emitting element) arranged thereon are arranged on one surface of the substrate 50. Each of the LED chips 53-1 to 53-29 has 516 LEDs 51 arranged in its longitudinal direction. The center-to-center distance k2 between adjacent LEDs 51 in the longitudinal direction of the LED chip 53 corresponds to the recording resolution of the image forming apparatus 100. Since the recording resolution of the image forming apparatus 100 in this embodiment is 1200 dpi, the LEDs 51 are arranged such that the center-to-center distance k2 between adjacent LEDs 51 in the longitudinal direction of the LED chips 53-1 to 53-29 is 21.16 μm. Therefore, the exposure range of the exposure head 4 in this embodiment is approximately 314 mm. The length of the photosensitive layer in the axial direction of the photosensitive drum 2 is 314 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 exposure head 4 of this embodiment has an exposure range that can form images on A4 size recording paper and A3 size recording paper.

[0052] The LED chips 53-1 to 53-29 are arranged in a staggered pattern in the axial direction of the photosensitive drum 2. Specifically, the LED chips 53-1 to 53-29 are alternately arranged in two rows along the axial direction of the photosensitive drum 2. That is, as shown in FIG. 8(b), counting from the left, the odd-numbered LED chips 53-1, 53-3, ..., 53-29 are mounted in a row in the longitudinal direction of the substrate 50. Also, counting from the left, the even-numbered LED chips 53-2, 53-4, ..., 53-28 are mounted in a row in the longitudinal direction of the substrate 50. The LED chips 53 are arranged in this manner. As a result, as shown in FIG. 8(c), the center-to-center distance k1 between the LEDs 51 arranged between one end of one LED chip 53 and the other end of the other LED chip 53 in adjacent LED chips 53 in the longitudinal direction of the LED chips 53 can be made equal to the center-to-center distance k2 between the adjacent LEDs 51 on one LED chip 53.

[0053] In this embodiment, the light-emitting elements are semiconductor LEDs, which are light-emitting diodes, but they may also be, for example, OLEDs (Organic Light Emitting Diodes). OLEDs are also called organic ELs (Organic Electro-Luminescence) and are current-driven light-emitting elements. The OLEDs are arranged in a line along the main scanning direction (the axial direction of the photosensitive drum 2) on a TFT (Thin Film Transistor) substrate, for example, and are electrically connected in parallel by power supply wiring that is also provided along the main scanning direction.

[0054] (lens array) Next, the lens array 52, which is a lens assembly, will be described. FIG. 8(d) is a schematic diagram of the lens array 52 as viewed from the photosensitive drum 2 side. FIG. 8(e) is a schematic perspective view of the lens array 52. ​​As shown in FIG. 8(d), the lens array 52 focuses light emitted from the light-emitting elements onto the photosensitive drum 2. The lens array 52 is a lens assembly having a plurality of lenses. These lenses are arranged in two rows along the arrangement direction of the plurality of LEDs 51. The lenses are alternately arranged such that one lens in one row is in contact with both of the adjacent lenses in the arrangement direction of the lenses in the other row. Each lens is a cylindrical glass rod lens and has a light incident surface 52b onto which light emitted from the LEDs 51 enters and a light exit surface 52a from which light incident from the light incident surface exits (see FIG. 5). The material of the lens is not limited to glass and may be plastic. The shape of the lens is also not limited to cylindrical and may be polygonal, such as a hexagonal prism.

[0055] The dotted line Z in Figure 8(e) indicates the optical axis of the lens. The exposure head 4 is moved by a movement mechanism in a direction generally along the optical axis of the lens indicated by the dotted line Z (hereinafter also referred to as the optical axis direction). 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 lens array 52 is a lens assembly having multiple lenses, and the aforementioned "optical axis" refers to the optical axis of any of these lenses. Strictly speaking, the multiple lenses in the lens array 52 may be slightly tilted relative to each other. This is due to assembly tolerances. However, deviations within the tolerance range mentioned here will not be taken into account when defining the direction of the optical axis. Therefore, the optical axes of the multiple lenses are considered to be in the same direction. Radiant light emitted from the LED 51 enters the lenses in the lens array 52. ​​The lenses have the function of focusing the incident radiation on the surface of the photosensitive drum 2.

[0056] When assembling the exposure head 4, the mounting position of the lens array 52 relative to the housing 54 is adjusted so that the distance between the light-emitting surface of the LED 51 and the light-incident surface 52b of the lens and the distance between the light-exiting surface 52a of the lens and the surface of the photosensitive drum 2 are approximately equal.

[0057] (Housing) 5, the housing 54 holds the lens array 52 and the substrate 50. In this embodiment, the housing 54 is a metal member formed by bending a plate material such as a zinc-plated steel plate or a cold-rolled steel plate. For example, the housing 54 is formed by pressing a metal plate such as a thin iron plate into a U-shape.

[0058] The housing 54 has a flat surface (facing surface) 54U in which a first opening 54a into which the lens array 52 is inserted is formed. The flat surface 54U faces the photosensitive drum 2 in the optical axis direction of the lenses of the lens array 52. ​​Note that this flat surface 54U is not limited to a flat surface, and may be a slightly curved surface. The housing 54 also has an extending portion 54R extending from one side in the short direction of the flat surface 54U in a direction away from the photosensitive drum 2. The housing 54 also has an extending portion 54L extending from the other side in the short direction of the flat surface 54U in a direction away from the photosensitive drum 2.

[0059] The extending portions 54R and 54L form a substrate support portion in the housing 54 for supporting the substrate 50 inserted through the second opening 54b. The flat portion 54U and the substrate support portions (extending portions 54R, 54L) are integral with each other to form the housing 54 that holds the lens array 52 and the substrate 50, and the cross section of the housing 54 is formed in a substantially U-shape. Because the housing 54 is formed in a substantially U-shape, a second opening 54b is formed on the side opposite the flat portion 54U. The second opening 54b is formed between the substrate support portions (extending portions 54L, 54R) that extend from the flat portion 54U toward the side away from the photosensitive drum. In other words, the second opening 54b of the housing 54 is formed between the substrate support portions (extending portions 54R, 54L) that support one side and the other side of the substrate 50 in the optical axis direction and the direction perpendicular to the axial direction.

[0060] The first opening 54a (lens mounting portion) of the housing 54 is an opening slightly larger than the lens array 52, and the lens array 52 is adhesively fixed to the housing 54 with an adhesive (not shown). The substrate 50 is formed slightly smaller than the housing 54, and the position of the substrate 50 is adjusted so that the optical axis of the LEDs 51 is aligned with the center of the lens array 52. ​​The substrate 50 is then adhesively fixed to the housing 54 with an adhesive (not shown) between the wall surfaces on both sides of the substrate 50 in the short direction of the housing 54 (the direction perpendicular to the long direction). This adhesive is, for example, an ultraviolet-curing adhesive, and is applied to the bonding location in a liquid or gel state and then hardened by irradiation with ultraviolet light.

[0061] When assembling the exposure head 4, the substrate 50 is adhesively fixed to the housing 54, and the gap between the substrate 50 and the housing 54 is further sealed with a sealant 59. As described above, the lens array 52 is also adhesively fixed to the housing 54 with an adhesive, just like the substrate 50. The gap between the lens array 52 and the housing 54 is also sealed with the sealant 59.

[0062] The sealing is performed using a moisture-curing silicone resin as the sealant 59. Note that the sealant 59 is not limited to the moisture-curing resin, and may be, for example, a photo-curing adhesive or a foam sealant made of a sponge material.

[0063] (Housing support member) The housing support member 55 supports the housing 54, which holds the substrate 50 and the lens array 52. ​​One end and the other end of the housing support member 55 in the longitudinal direction are fixed to the housing 54 by a connecting member such as an ultraviolet-curing adhesive, and the housing support member 55 is provided integrally with the housing 54. The housing support member 55 is a longitudinal member extending in the axial direction of the photosensitive drum 2. The housing support member 55 is formed in a U-shape. The housing support member 55 has a right side wall 55R as a first opposing portion, a left side wall 55L as a second opposing portion facing the right side wall 55R across the housing 54, and a bottom surface portion 55D facing the flat surface portion 54U of the housing 54 between the right side wall 55R and the left side wall 55L. The bottom surface portion 55D, the right side wall 55R, and the left side wall 55L are integral with each other to form a duct between the housing 54 and the bottom surface portion 55D, and the cross section of the bottom surface portion 55D is formed in a substantially U-shape. A bottom surface 55D of the housing support member 55 is provided with a plurality of openings 55a in the longitudinal direction, which is the axial direction of the photosensitive drum 2.

[0064] The opening 55a of the housing support member 55 is provided at a position facing the surface (rear surface of the board 50) opposite to the mounting surface (front surface of the board 50) on which the LEDs 51 are mounted of the board 50. The opening 55a is provided between the right side wall 55R and the left side wall 55L in the short direction perpendicular to the long direction.

[0065] The right side wall 55R is a first opposing portion that faces the extending portion 54R, which is a board support portion on one side of the housing 54 in the short side direction. As shown in FIG. 5 , the right side wall 55R, which is the first opposing portion, is provided between the housing 54 and the drum unit 23, which is an adjacent portion adjacent to the housing 54, on one side in the short side direction perpendicular to the axial direction of the photosensitive drum 2. The right side wall 55R is provided across the axial direction of the photosensitive drum 2 so as to separate the housing 54 and the drum unit 23.

[0066] The left side wall 55L is a second opposing portion that faces the left side wall 55R, which is a substrate support portion on the other side of the casing 54 in the short side direction, and faces the right side wall 55R across the casing 54. As shown in FIG. 5, the left side wall 55L, which is the second opposing portion, is provided on the other side in the short side direction between the casing 54 that holds the substrate 50 and the developing unit 24 that is the developing means. Like the right side wall, the left side wall 55L is provided across the axis direction of the photosensitive drum 2 so as to separate the casing 54 and the developing unit 24.

[0067] By providing the housing support member 55 integrally with the housing 54, the airflow sent from the duct unit 60 is blown onto the back surface of the substrate 50 through the opening 55a of the housing support member 55. Moreover, the airflow blown onto the back surface of the substrate 50 is blown in a direction perpendicular to the back surface of the substrate 50.

[0068] In this way, the housing support member 55 is provided over the longitudinal direction, which is the axial direction of the photosensitive drum 2, and has an opening 55a at a position facing the back surface of the substrate 50. As a result, the airflow sent from the duct unit 60 is blown onto the back surface of the substrate 50 through the opening 55a of the housing support member 55. A duct (closed space) is formed between the housing support member 55 of the exposure head 4 and the housing 54, which allows the airflow blown onto the back surface of the substrate 50 through the opening 55a to circulate in the longitudinal direction of the substrate 50. In other words, the housing support member 55 forms part of a duct that cools the exposure head 4.

[0069] As described above, the exposure head 4 is configured as an integrated head unit by the substrate 50 having the LEDs 51, the lens array 52 made up of a plurality of lenses, the housing 54, and the housing support member 55.

[0070] (moving mechanism) The movement mechanism for the exposure head 4 is made up of a lifting duct 69, a rotating arm 65, and a link member (not shown). In this embodiment, the movement mechanism has the function of moving not only the exposure head 4 but also the developing unit 24 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.

[0071] 13 and 14, the movement mechanism including the lift duct 69 and the rotary arm 65 will be described. Fig. 13 is a perspective view of the cartridge tray as seen from below. Fig. 14 is a cross-sectional view of the exposure head as seen from the front, taken along arrow XX in Fig. 13.

[0072] The lifting duct 69 is an exposure support member that detachably supports the exposure head 4, and is provided in the main body of the image forming apparatus 100 together with the cartridge tray 30.

[0073] The lifting duct 69 is provided in the center of the tray, corresponding to the space between the developing support portion that supports the developing unit 24 of the cartridge tray 30 and the drum support portion that supports the drum unit 23. The lifting duct 69 is provided in the center of the tray of the cartridge tray 30 so as to be movable between an exposure position where the photosensitive drum 2 is exposed to light and a retracted position where the lifting duct 69 is retracted from the exposure position. Both longitudinal ends of the lifting duct 69 are supported from below by a pivot arm 65. The lifting duct 69 is moved integrally with the exposure head 4 in a direction (movement direction) perpendicular to the axial direction of the photosensitive drum 2 by the pivot arm 65. The lifting duct 69 is moved to the exposure position or the retracted position by the rotation of the pivot arm 65.

[0074] The lifting duct 69 has a longitudinal shape that extends in the front-to-rear direction (the axial direction of the photosensitive drum) like the exposure head 4 so that it can support the entire exposure head 4, and its central portion has a shape with openings at the top and bottom. The lifting duct 69 forms a duct with one opening (not shown) communicating with the opening 55a of the exposure head 4 and the other opening 69a (see Figure 13) communicating with the opening 60a of the duct unit 60 (see Figure 12). The lifting duct 69 supports the exposure head 4, and at the same time forms part of a duct (closed space) that communicates between the exposure head 4 and the duct unit 60 and forms a flow path for the airflow that cools the exposure head 4.

[0075] Therefore, the lifting duct 69 allows the airflow generated by the duct unit 60 to flow through the upper and lower openings onto the back surface of the substrate 50 of the exposure head 4. Therefore, the lifting duct 69 can allow the airflow generated by the duct unit 60 to flow onto the back surface of the substrate 50 of the exposure head 4 without leaking to the adjacent developing unit 24 or drum unit 23 side, thereby reducing toner scattering inside the device.

[0076] Furthermore, at both longitudinal ends of the lifting duct 69, there are disposed pivot arms 65 that move the exposure head 4 between an exposure position close to the photosensitive drum 2 and a retracted position retracted from the exposure position. The pivot arms 65 are pivotally provided on the developing unit side of the cartridge tray 30. One end of the pivot arm 65 in the left-right direction perpendicular to the axial direction of the photosensitive drum 2 is supported so as to be pivotable about an axis parallel to the axial direction. The other end of the pivot arm 65 in the left-right direction supports both ends of a region (range Lm in FIG. 13) outside the opening of the lifting duct 69 in the axial direction. The pivot arm 65 is configured to move in conjunction with the opening and closing of the inner door 102 by a link member (not shown).

[0077] 13, the range of the opening forming the duct is indicated as La, and the range of arrangement of the rotary arm 65 is indicated as Lm. The range La of the opening of the lifting duct 69 is provided within the range Lm of arrangement of the rotary arm 65.

[0078] Note that range Lc in Figure 13 is the area where the connector 57 of the exposure head 4 is provided, and is outside the duct area shown by range La in Figure 13, and is provided between the duct area and the area shown by one of ranges Lm in Figure 13.

[0079] Furthermore, the area La forming the duct includes most of the board 50 on which the LEDs 51 are mounted, and by blowing airflow onto this area La, it is possible to sufficiently cool the exposure head 4. The area Lc is where the connector 57 of the signal line that transmits the drive signal to the board 50 on which the LEDs 51 are mounted is 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.

[0080] As a result, air taken in from outside the apparatus by duct unit 60 passes through lift duct 69 and is blown from opening 55a of exposure head 4 onto the rear surface of substrate 50. In addition, the airflow blown onto the rear surface of substrate 50 from opening 55a of exposure head 4 is exhausted to the outside of the apparatus by duct unit 60 through lift duct 69.

[0081] (Duct unit) The image forming apparatus 100 also includes a detachable duct unit 60. The duct unit 60 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 seen from above.

[0082] The duct unit 60 is an exposure cooling unit that communicates with an opening 69 a formed by the cartridge tray 30 and the lifting duct 69 and cools the exposure head 4 by airflow through the lifting duct 69 .

[0083] The duct unit 60 has an exhaust duct 62 that communicates with the lift duct 69 and forms a space for circulating the air introduced from the lift duct 69. An opening 60a that communicates with the lift duct 69 and introduces air from the lift duct 69 is provided on the upper surface of the exhaust duct 62 for each exposure head. The exhaust duct 62 is provided with a fan 68 that generates an air current.

[0084] The duct unit 60 has an intake duct 61 that communicates with the lift duct 69 and forms a space for circulating air to be introduced into the lift duct 69. An opening 60a that communicates with the lift duct 69 and introduces air into the lift duct 69 is provided on the upper surface of the intake duct 61 for each exposure head. The intake duct 61 is provided with a fan 67 that generates an air current.

[0085] The duct unit 60 is integrally provided with fans 67 and 68, an intake duct 61, and an exhaust duct 62, and is detachably mounted to the main body of the image forming apparatus 100 directly below the cartridge tray 30.

[0086] Each opening 60a of the duct unit 60 is provided at a position opposite to an opening 69a of the lifting duct 69 for each exposure head, and is connected to the opening 69a to communicate with the exposure head 4, forming a closed space.

[0087] (Cooling structure of exposure head) The cooling configuration of the exposure head will now 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 broken line, and the air flow indicated by the broken line is also referred to as exposure cooling air flow.

[0088] The exposure head 4 dissipates heat according to the amount of light emitted by the LEDs 51, and because it is located in close proximity to a developing device that uses heat-sensitive toner, a cooling means is necessary. In particular, when the image formation process is repeated frequently, i.e., when used in a highly productive device, or when continuously outputting high-density images, the light emission time is long and the amount of light emitted is large. Therefore, the amount of heat generated by the LEDs 51 and the circuit on the board 50 on which they are mounted also increases.

[0089] As a countermeasure to this, for example, the housing 54 of the exposure head 4 is used as a heat sink, making it easier for the exposure head 4 to dissipate heat and less likely to accumulate heat. However, even in such a case, it is conceivable that the exposure head 4 will not be cooled in time, causing heat accumulation and increasing the amount of heat dissipated to the surrounding area. As a result, the toner around the development unit 24 and some of the circulating toner inside the development unit may fuse together, potentially resulting in poor image quality.

[0090] Even if a structure for cooling the development unit 24 is provided, it is easy to imagine that the heat accumulated due to the light emission of the LED 51 will prevail in the area close to the exposure head 4. Therefore, it is desirable to provide a cooling structure for the exposure head 4 (exposure cooling airflow) to reduce the amount of heat dissipated around the exposure head 4.

[0091] The image forming apparatus 100 has an exposure head 4, a lifting duct 69, a cartridge tray 30, and a duct unit 60. The exposure head 4 is attached to the lifting duct 69 arranged in the image forming apparatus 100 and is integrated with the lifting duct 69. When the exposure head 4 is attached to the lifting duct 69, an opening 55a (see FIG. 7) of a housing support member 55 of the exposure head 4 communicates with one opening (not shown) of the lifting duct 69. The lifting duct 69 forms a duct that communicates between the exposure head 4 and the duct unit 60. The duct unit 60 is attached to the image forming apparatus 100 directly below the cartridge tray 30. In other words, the duct unit 60 is provided on the opposite side of the exposure head 4 from the photosensitive drum 2. When the duct unit 60 is attached to the image forming apparatus 100, the opening 60a (see FIG. 12) of the duct unit 60 communicates with the other opening 69a (see FIG. 13) of the lifting duct 69.

[0092] In this way, the housing support member 55 of the exposure head 4, the lift duct 69, the cartridge tray 30, and the duct unit 60 form a cooling duct, which is a single continuous closed space. Each exposure head 4 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 55, the lift duct 69, the cartridge tray 30, and the duct unit 60.

[0093] 11 and 12, fan 67 located near the front of the device functions as an intake fan that draws air (fresh air) from outside the device into duct unit 60. Fan 68 located near the rear of the device functions as an exhaust fan that exhausts air from inside duct unit 60 to the outside of the device.

[0094] In the exposure cooling air flow indicated by the dashed lines in FIG. 11 , when fans 67 and 68 rotate, air from outside the apparatus is introduced through an air intake port 61a and passes through louvers (not shown) on the exterior cover of the image forming apparatus. The air introduced through the air intake port 61a passes through an air intake duct 61 and is exhausted from each opening 60a of the air intake duct 61. The air exhausted from each opening 60a is blown onto the exposure head 4 through a lift-up duct 69. The air blown onto the exposure head 4 through the lift-up duct 69 is circulated from the front to the rear of the apparatus along the axial direction of the photosensitive drum 2 and is introduced into the exhaust duct 62 through each opening 60a of the exhaust duct 62 via the lift-up duct 69. The air introduced into the exhaust duct 62 from each opening 60a is exhausted to the outside of the apparatus from the exhaust ports 62a of the exhaust duct 62 through louvers (not shown) on the exterior cover.

[0095] The fans 67 and 68 in the duct unit 60 are controlled based on temperature detection sensors (not shown) arranged on the circuit boards 50 of each color. As a result, the fans do not rotate all the time, but rather start rotating when the temperature detected by the temperature detection sensors reaches a predetermined threshold. In this way, by minimizing the operation of the exposure cooling flow by the fans and keeping the air volume to a minimum, the possibility of toner scattering inside the device is reduced from the viewpoint of control.

[0096] (Configuration to prevent airflow from leaking from inside the exposure head) Next, the air flow path within the exposure head 4 and the structure for preventing the air flow from leaking out will be described with reference to FIGS.

[0097] Fig. 15 is a diagram showing the longitudinal lengths of the sheet and openings of the exposure head according to Example 1. Fig. 16 is a cross-sectional view of the exposure head according to Example 1, taken along the line XX in Fig. 15, at approximately the center of the longitudinal direction of the exposure head. Fig. 16 shows the lifting duct and exposure head, while Fig. 15 shows only the exposure head. Fig. 17 is a perspective view of the exposure head according to Example 1, and Fig. 18 is a perspective view of the exposure head, lifting duct, and duct unit according to Example 1.

[0098] The exposure head 4 faces a temperature rise problem due to heat generated by the substrate 50. Therefore, the exposure head 4 is configured to suppress temperature rise by circulating air in the space enclosed by the substrate 50, the housing 54, and the housing support member 55. However, a small gap exists between the housing 54 and the housing support member 55. This gap exists as a gap t in the left-right direction (indicated by the arrow) in FIG. 16 and is necessary from the perspectives of ease of assembly and component precision. From the perspective of ease of assembly, if this gap t were not present, when the housing 54 and the housing support member 55 are assembled in the vertical direction in FIG. 16 , either the housing 54 or the housing support member 55, or both, would be deformed left-right during assembly. This could affect the optical system, such as the substrate 50 and the lens array 52. ​​From the perspective of component precision, the housing 54 and the housing support member 55 are elongated in the front-to-rear direction (axial direction) as a whole, and a certain amount of warping could occur during the component manufacturing process. From the above, it can be seen that a certain amount of gap t is necessary between the housing 54 and the housing support member 55 in order to accommodate dimensional tolerances including warpage of parts and assemble without deformation. However, from the perspective of the airflow that cools the exposure head 4, this gap t is undesirable, and there is a risk that toner, tiny dust particles, etc. will be scattered due to blowing out or suction through the gap t.

[0099] Therefore, in this embodiment, in order to reduce the scattering of foreign matter such as toner due to the outflow of air from this gap t, the gap t between the housing 54 and the housing support member 55 that constitute the exposure head 4 is sealed with a sealing member 71, as shown in Figure 16.

[0100] The sealing member 71 seals the gap t between the housing 54 and the housing support member 55, which face each other on one side and the other side of the substrate 50, in the left-right direction (the direction of the arrow shown in Figure 16) perpendicular to the optical axis direction and the axial direction.

[0101] As described above, the housing 54 includes the second opening 54b and holds the substrate 50 and the lens array 52. ​​The housing support member 55 is provided integrally with the housing 54 so as to cover the second opening 54b of the housing 54, and forms a space between the housing 54 and the housing 54 for air circulation.

[0102] The second opening 54b of the housing 54 is formed between extensions 54R and 54L, which are board support parts that support one side and the other side of the board 50 in the left-right direction. The housing support member 55 has a right side wall 55R that faces the extension 54R on one side of the housing in the left-right direction, and a left side wall 55L that faces the extension 54L on the other side of the housing 54 and faces the right side wall 55R with the housing 54 in between.

[0103] The sealing member 71 seals the gap t between the one extension portion 54R and the right side wall 55R, which are opposed in the left-right direction, and the gap t between the other extension portion 54L and the left side wall 55L, in the axial direction (front-rear direction). As a result, the sealing member 71 prevents airflow from leaking out from the two gaps t in the left-right direction of the housing 54 and the housing support member 55 shown in Figures 17 and 18, and can reduce the scattering of foreign matter such as toner due to the outflow of airflow.

[0104] As described above, the housing support member 55 has a plurality of openings 55a (see FIG. 7) that communicate with the duct unit 60 that generates an airflow that cools the exposure head 4. The housing support member 55 circulates air through these openings 55a into the space formed between the housing 54 and the housing support member 55. The openings 55a of the housing support member 55 are provided at positions facing the surface of the substrate 50 held by the housing 54 opposite the surface on which the LEDs 51 are mounted (see FIG. 5).

[0105] The sealing member 71 is longer in the axial direction than the length from one end 55aF to the other end 55aB of the area where the plurality of openings 55a of the housing support member 55 is provided (see FIGS. 7 and 15). The range from one end 55aF to the other end 55aB, which is the area where the plurality of openings 55a is provided, is the same range as the range La of the openings of the lift-down duct 69 shown in FIG. 13. In other words, the length Ls of the sealing member 71 from one end 71F to the other end 71B in the axial direction is longer than the range La from one end 55aF to the other end 55aB, which is the area where the plurality of openings 55a of the exposure head 4 is provided.

[0106] 18, the axial length Ls of the sealing member 71 can be said to be longer than the range La, which is the area where the opening 60a of the duct unit 60 is provided. As described above, the opening of the lift-down duct 69 also communicates with the opening 60a of the duct unit 60, and the area where the opening 60a of the duct unit 60 is provided, from one end 60aF to the other end 60aB, is the same as the range La of the opening of the lift-down duct 69 shown in FIG. 13. Therefore, it can be said that the axial length Ls of the sealing member 71 from one end 71F to the other end 71B is longer than the range La, which is the area where the opening 60a of the duct unit 60 is provided, from one end 60aF to the other end 60aB.

[0107] The sealing member 71 is a sheet member. Hereinafter, the sealing member 71 will also be referred to as a sheet member 72.

[0108] With the above configuration, the range Ls of the sheet member 72 covers the entire range La of the opening, and the sheet member 72 can prevent the airflow from flowing out from the gap t of the exposure head 4.

[0109] One side of the sheet member 72 is attached to and held by the housing support member 55 in the left-right direction, and the other side is bent toward the gap between the housing 54 and the housing support member 55 and inserted into the gap t, and abuts against the housing 54 due to the reaction force generated when the sheet member 72 is bent.

[0110] 16, sheet member 72 is bent from attachment portion 56 of housing support member 55 and abuts against housing 54. By bending sheet member 72, housing 54, which is in contact with sheet member 72, is configured to continuously receive the reaction force of sheet member 72. This configuration reduces the outflow of airflow due to bending or rippling of sheet member 72, and ensures that sheet member 72 and housing 54 abut securely at gap t.

[0111] Here, if the thickness of the sheet member 72 is small, there is a high risk of the sheet member 72 warping or rippling when bent. On the other hand, if the thickness of the sheet member 72 is large, the reaction force that the housing 54 continues to receive increases, which may affect the optical system, such as the substrate 50 and lens array 52, held in the housing 54. Therefore, it is necessary to select an appropriate thickness for the sheet member 72.

[0112] Therefore, in this embodiment, a polyester film having a thickness of 100 μm or less is used for the sheet member 72. For example, Lumirror S10, a polyester film manufactured by Toray Industries, Inc., is used as the sheet member 72, and has a thickness of 38 μm.

[0113] Although the sheet member 72 has been described as being bent and inserted into the gap t to abut against the housing, it may abut against both the housing 54 and the housing support member 55.

[0114] Specifically, the housing support member 55 has an attachment portion 56 for attaching the sheet member 72 to a surface opposite the surface facing the housing 54 in the left-right direction. The attachment portion 56 is provided on the outer surfaces of the right side wall 55R and the left side wall 55L of the housing support member 55. The attachment portion 56 has a recessed (stepped) shape toward the housing in the left-right direction compared to a portion of the housing support member 55 adjacent to the attachment portion 56. This recess, that is, the attachment portion 56, is larger in the left-right direction than the thickness of the sheet member 72. Therefore, even when the sheet member 72 is attached to the attachment portion 56 on each side wall of the housing support member 55, it does not protrude outward from the portion adjacent to the attachment portion 56. This reduces the possibility of the sheet member 72 getting caught around the periphery of the exposure head 4 and being turned over or peeled off when the exposure head 4 is moved to the exposure position or the retracted position.

[0115] Example 2 The exposure head 4 according to Example 2 will be described with reference to Figure 19. Figure 19 is a cross-sectional view of the exposure head 4 according to Example 2. The general configuration of the exposure head 4 and the image forming apparatus 100 is almost the same as in Example 1 described above, so members having equivalent functions are given the same reference numerals and descriptions thereof will be omitted.

[0116] As shown in FIG. 19 , one side of the sheet member 72 is attached to the upper surfaces of the right side wall 55R and the left side wall 55L of the housing support member 55. That is, in this embodiment, the attachment portion 56 is provided on the upper surfaces of the right side wall 55R and the left side wall 55L of the housing support member 55, respectively. In the configuration of this embodiment, the sheet member 72 is bent from the attachment portion 56 of the housing support member 55 and inserted into the gap t, where it abuts against the housing 54. By bending the sheet member 72 in this manner, the housing 54 that the sheet member 72 abuts against is continuously subjected to the reaction force of the sheet member 72. The configuration of this embodiment also reduces the outflow of airflow due to bending or rippling of the sheet member 72, and ensures that the sheet member 72 and the housing 54 abut against each other in the gap t.

[0117] Therefore, the bending angle of the sheet member 72 is not limited to the angle in Example 1 or this example. Any other bending angle may be used as long as the sheet member 71 continues to abut against the housing 54 at the gap t due to the reaction force generated by the bending.

[0118] Example 3 An exposure head 4 according to Example 3 will be described using Figure 20. Figure 20 is a cross-sectional view of the exposure head 4 according to Example 3. Since the general configuration of the exposure head 4 and the image forming apparatus 100 is almost the same as in Example 1 described above, members having equivalent functions are given the same reference numerals and descriptions thereof will be omitted.

[0119] In the above-described embodiment, the sealing member 71 is the sheet member 72, but the present invention is not limited to this. The sealing member 71 may be a filler (sealant) 73.

[0120] 20, a moisture-curing silicone resin is applied as a filler 73 to the gap t between the housing support member 55 and the housing 54 to seal the gap t. The filler 73 prevents air from flowing out of the gap t of the exposure head 4, and suppresses the scattering of toner, fine dust, and the like.

[0121] The filler (sealant) 73 is not limited to a moisture-curing resin, but may be, for example, a photo-curing adhesive or a foam sealant made of a sponge material. [Explanation of symbols]

[0122] La...range Ls...length t...gap 1...Image forming unit 2...Photosensitive drum 4...Exposure head 23...Drum unit 24...Developing unit 30...Cartridge tray 50...Substrate 51...LED 52...Lens array 53...LED chip 54...Case 54L...extension part 54R…Extension part 54a...1st opening 54b…Second opening 55...Housing support member 55L…Left side wall 55R…Right side wall 55a...Aperture 55aB...end 55aF...end 56 ...Attachment part 59...Sealant 60...Duct unit 60a...opening 60aB...end 60aF...end 69...Lift duct 69a...Aperture 71...Sealing member 71B...other end 71F…One end 72 ... Sheet material 73...Filler

Claims

1. a substrate on which a plurality of light-emitting elements that emit light to expose a photosensitive member are arranged along the axial direction of the photosensitive member; a lens array having a plurality of lenses that condenses the light emitted from the light-emitting element onto the photosensitive member; a housing including an opening and holding the substrate and the lens array; a housing support member that is integrally provided with the housing so as to cover the opening of the housing and that forms a space between the housing and the housing for air circulation; a sealing member that seals a gap between the housing and the housing support member that face each other on one side and the other side of the substrate in an optical axis direction along the optical axis of the lens and in a direction perpendicular to the axial direction, An exposure apparatus characterized by:

2. the opening of the housing is formed between substrate support parts that support one side and the other side of the substrate in an optical axis direction along the optical axis of the lens and in a direction perpendicular to the axial direction, The housing support member is a first opposing portion opposing the board support portion on one side of the housing in the orthogonal direction; a second opposing portion that faces the substrate support portion on the other side of the housing in the orthogonal direction and faces the first opposing portion across the housing, the sealing member seals a gap between the substrate support portion on one side and the first opposing portion, which are opposed in the orthogonal direction, and a gap between the substrate support portion on the other side and the second opposing portion, across the axial direction.

2. An exposure apparatus according to claim 1.

3. the housing support member has an opening communicating with an exposure cooling unit that generates an airflow that cools the exposure device, the opening of the housing support member is provided at a position facing a surface of the substrate held by the housing opposite to a surface on which the light emitting element is mounted; 2. An exposure apparatus according to claim 1.

4. 4. An exposure apparatus according to claim 3, wherein the sealing member is longer in the axial direction than the length from one end to the other end of the region where the opening of the housing support member is provided.

5. 2. The exposure apparatus according to claim 1, wherein the sealing member is a sheet member.

6. The exposure apparatus according to claim 5, characterized in that one side of the sheet member in the perpendicular direction is attached and held to the housing support member, and the other side is bent toward the gap between the housing and the housing support member and inserted into the gap, and abuts against the housing due to the reaction force generated when the sheet member is bent.

7. the housing support member has an attachment portion for attaching the sheet member to a surface opposite to a surface facing the housing in the orthogonal direction, 7. The exposure apparatus according to claim 6, wherein the attachment portion has a recessed shape that is recessed toward the housing side in the orthogonal direction compared to a portion adjacent to the attachment portion.

8. 6. The exposure apparatus according to claim 5, wherein the sheet member is a polyester film having a thickness of 100 [mu]m or less.

9. 2. The exposure apparatus according to claim 1, wherein the sealing member is a filler.

10. 2. The exposure apparatus according to claim 1, wherein the light emitting element is an organic electroluminescent element.

11. 11. An image forming apparatus comprising: a photosensitive member; an exposure device according to claim 1; and an exposure cooling unit that generates an airflow for cooling the exposure device.

Images