Image forming device

Abstract

To reliably clean deposits adhering to an emission surface of a lens by a cleaning member.SOLUTION: An image forming device comprises: a photoreceptor; an exposure head that includes a substrate on which a plurality of light-emitting elements are mounted along a longitudinal direction being an axial direction of the photoreceptor, and a lens array composed of a plurality of lenses that condense light emitted from the light-emitting elements onto the photoreceptor; an elongated cleaning rod that is inserted from the outside of the image forming device and cleans by sliding in the longitudinal direction along an emission surface of the lenses; and a guide member that guides the cleaning rod inserted from the outside of the image forming device. The cleaning rod comprises: a cleaning member that abuts the emission surface of the lenses to clean deposits adhering to the emission surface of the lens; a first portion whose cross-sectional shape in a direction orthogonal to the longitudinal direction has a first cross-sectional shape; and a second portion which is provided at a position different from the first portion in the longitudinal direction and has a second cross-sectional shape different from the first portion.SELECTED DRAWING: Figure 32

Description

[Technical Field]

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

[0002] In electrophotographic image forming devices such as printers and copiers, a solid-state exposure head is used as one of the means for exposing a photoconductor. A fixed exposure head has multiple light-emitting elements such as LEDs arranged along the axial direction of the photoconductor, and exposes the photoconductor all at once in the axial direction.

[0003] The fixed exposure head is equipped with a lens array, which consists of multiple lenses arranged in the axial direction facing the light emitting element, to focus the light beam emitted from the light emitting element onto the photosensitive element. Because the focal length of this lens array is extremely short, the exposure head must be placed close to the photosensitive element. However, toner may be floating near the photosensitive element. If this floating toner adheres to the light emitting surface of the lens array, the amount of light irradiating the photosensitive element becomes uneven, which can result in image defects such as uneven density.

[0004] Therefore, in an image forming apparatus equipped with a solid-state exposure head, a configuration has been disclosed in which a cleaning member is provided to clean the exit surface of the lens array in the fixed exposure head. In Patent Document 1, a hook provided on the cleaning member is engaged with a guide groove provided on the exposure head, so that the cleaning member comes into contact with the exit surface of the lens, thereby enabling cleaning. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-173811 Summary of the Invention [Problem to be solved by the invention]

[0006] However, with the above-described conventional technology, if an operator roughly operates the cleaning member, the operating force may cause the cleaning member to separate from the light exit surface of the lens. If the cleaning member separates from the light exit surface of the lens, it becomes difficult to reliably clean the toner adhering to the light exit surface of the lens.

[0007] An object of the present invention is to reliably clean deposits adhering to the light exit surface of a lens with a cleaning member. [Means for solving the problem]

[0008] A typical configuration of the present invention includes a photosensitive body, a substrate on which a plurality of light-emitting elements are mounted along the longitudinal direction, which is the axial direction of the photosensitive body, and a lens array consisting of a plurality of lenses that focus light emitted from the light-emitting elements onto the photosensitive body, and is equipped with an exposure head that exposes the photosensitive body, a longitudinal cleaning rod that is inserted from outside the image forming device and cleans the exit surface of the lens by rubbing it in the longitudinal direction, and a guide member that guides the cleaning rod inserted from outside the image forming device, wherein the cleaning rod includes a cleaning member that abuts against the exit surface of the lens to clean any deposits adhering to the exit surface of the lens, a first portion having a first cross-sectional shape in a direction perpendicular to the longitudinal direction, and a second portion that is located at a position different from the first portion in the longitudinal direction and has a second cross-sectional shape different from the first portion. [Effects of the Invention]

[0009] According to the present invention, the cleaning member can reliably clean the deposits adhering to the light exit surface of the lens. [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] (a) is a perspective view showing the cartridge tray, the inner door in a closed state, and the exposure head in the exposure position; (b) is a perspective view showing the cartridge tray, the inner door in an open state, and the exposure head in the retracted position; [Figure 6] Schematic cross-sectional view of the exposure head [Figure 7] A perspective view of the exposure head seen from above [Figure 8] A perspective view of the exposure head seen from below [Figure 9] (a), (b), and (c) are diagrams showing the substrate of the exposure head, and (d) and (e) are diagrams showing the lens array. [Figure 10] Cross-sectional perspective view of the exposure head [Figure 11] A cross-sectional view showing the sealing structure of the front pilot hole of the exposure head. [Figure 12] A cross-sectional view showing the sealing structure of the rear pilot hole of the exposure head. [Figure 13] Perspective view of the cartridge tray from below [Figure 14] Cross-sectional view taken along arrow XX in Figure 13 [Figure 15] Cross-sectional view along arrow AA in Figure 2 [Figure 16] Perspective view of the duct unit [Figure 17] (a) is a diagram showing the longitudinal lengths of the sheet and the opening of the exposure head according to the first embodiment; (b) is a top view of the exposure head according to the first embodiment; [Figure 18] (a) and (b) are cross-sectional views of the optical print head according to the first embodiment taken along the short side. [Figure 19] FIG. 1 is a longitudinal cross-sectional view of an optical print head according to a first embodiment; [Figure 20] 1A and 1B are perspective views of a housing support member according to a first embodiment; [Figure 21] FIG. 1 is a perspective view of an exposure head, a lifting duct, and a duct unit according to a first embodiment; [Figure 22](a) is a perspective view seen from the front surface, cut in a direction perpendicular to the axial direction of the photosensitive drum at the center position of the positioning pin; (b) is a perspective view seen from the rear surface, cut in a direction perpendicular to the axial direction of the photosensitive drum at the center position of the positioning pin. [Figure 23] 1 is a perspective view of the positioning member after installation; [Figure 24] 1 is a perspective view of a positioning member before attachment; [Figure 25] FIG. 10 is a perspective view showing the shape of a positioning member; [Figure 26] 1A, 1B, and 1C are diagrams showing the configuration of a cleaning rod according to a first embodiment; [Figure 27] 1A and 1B are diagrams showing the configuration of a cleaning rod according to a first embodiment; [Figure 28] 1A, 1B, and 1C are diagrams showing a guide structure for a cleaning rod according to a first embodiment; [Figure 29] 1A and 1B are diagrams illustrating the configuration of a first guide member according to a first embodiment; [Figure 30] 1A and 1B are diagrams illustrating the configuration of a second guide member according to the first embodiment. [Figure 31] 1A, 1B, and 1C are diagrams showing the configuration of a cleaning member according to a first embodiment; [Figure 32] 1A and 1B are diagrams showing the shape of a notch according to Example 1. [Figure 33] (a) and (b) are diagrams showing the effect of the notch portion according to Example 1. [Figure 34] 1A and 1B are diagrams showing the configuration of a stopper according to Example 1. [Figure 35] (a)(b) is a diagram showing the length relationship of each part according to Example 1. [Figure 36] Cross section of rear pilot hole [Figure 37] Figure showing the results of actual measurements to confirm the presence of foreign matter 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 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] The image forming apparatus 100 also includes a cartridge tray 30 (30Y, 30M, 30C, 30K) for each image forming unit (see FIGS. 5(a) and 5(b)). The cartridge tray 30 supports the drum unit 23 and the 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, as shown in Fig. 5(b), and retracts the exposure head 4 to the retracted position. 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. 5(a), 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. Furthermore, one side in the longitudinal direction of the exposure head 4 means the front side as defined here, and the other side means the rear side as defined here.

[0044] (Exposure head) Next, the exposure head 4 will be described with reference to Figures 6 to 8. Figure 6 is a schematic cross-sectional view of the exposure head 4 provided in the image forming apparatus of this embodiment. Figure 7 is a perspective view of the exposure head 4 as seen from above. Figure 8 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] 7 and 8, the exposure head 4 has an elongated shape (longitudinal shape) extending in the axial direction of the photosensitive drum 2. As shown in Fig. 6, the exposure head 4 includes a substrate 50, a light-emitting element 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 an LED 51 (Light Emitting Diode) as a light-emitting element that emits 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. 9. First, the substrate 50 will be described. Fig. 9(a) is a schematic perspective view of the substrate 50. Fig. 9(b) shows the arrangement of a plurality of LEDs 51 provided on the substrate 50, and Fig. 9(c) shows an enlarged view of Fig. 9(b).

[0048] (substrate) An LED chip 53 is mounted on the substrate 50. As shown in Fig. 9(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 now be described in more detail. As shown in FIGS. 9(b) and 9(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. 9(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. 9(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. 9(d) is a schematic diagram of the lens array 52 as viewed from the photosensitive drum 2 side. FIG. 9(e) is a schematic perspective view of the lens array 52. ​​As shown in FIG. 9(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. 6). 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 9(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 focus 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) 6, 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 plated material such as a galvanized steel plate or a cold-rolled steel plate. For example, the housing 54 is formed into a U-shape by pressing a metal sheet such as a thin metal plate having a thickness of about 1 mm.

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

[0059] The extensions 54R and 54L form a substrate support portion in the housing 54 for supporting the substrate 50 inserted through the second opening 54b. The reference portion 54U and the substrate support portions (extensions 54R and 54L) are integral and form the housing 54 that holds the lens array 52 and the substrate 50, and its cross section 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 reference portion 54U. The second opening 54b is formed between the substrate support portions (extensions 54L and 54R) that extend from the reference portion 54U to 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 (extensions 54R and 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 of the housing 54 is one size larger than the lens array 52, and is a lens attachment portion into which the lens array 52 is inserted. As described above, the attachment position of the lens array 52 relative to the housing 54 is adjusted when assembling the exposure head 4, and the lens array 52 is then adhesively fixed to the housing 54 at multiple locations in the longitudinal direction with adhesive 58. Because the first opening 54a of the housing 54 is one size larger than the lens array 52, the lens array 52 is fixed to the housing 54 with a small gap in the short direction perpendicular to the longitudinal direction.

[0061] The substrate 50 is formed to be slightly smaller than the housing 54. In other words, the second opening 54b of the housing 54 is an opening slightly larger than the substrate 50 and is a substrate mounting portion into which the substrate 50 is inserted. The mounting position of the substrate 50 is adjusted between the wall surfaces (extensions 54R, 54L) of the housing 54 on both sides of the substrate 50 in the short direction 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 at multiple locations in the longitudinal direction with adhesive 58 (see FIG. 10 ). Because the second opening 54b of the housing 54 is an opening slightly larger than the substrate 50, the substrate 50 is also fixed to the housing 54 with adhesive 58 with a slight gap in the short direction.

[0062] The adhesive 58 is, for example, an ultraviolet-curing adhesive, which is applied in liquid or gel form to the bonding points and then hardened by irradiation with ultraviolet light. Note that the bonding points using the adhesive 58 are provided at multiple locations in the longitudinal direction, at the same positions on both the left and right sides, but this is not limitative.

[0063] 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. Similarly, the lens array 52 is adhesively fixed to the housing 54, and the gap between the lens array 52 and the housing 54 is also sealed with a sealant 59.

[0064] 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.

[0065] (Pilot hole in the housing) 11 and 12, the housing 54 has a reference surface 54U1 having a first opening (slot) 54a into which the lens array 52 is inserted. Furthermore, the housing 54 has pin fixing surfaces 54U3 on both sides of the reference surface 54U1 in the longitudinal direction, which are offset from the reference surface 54U1 in a direction away from the photosensitive drum 2 via jockle shapes 54U2. The above-mentioned positioning pins are fixed to the pin fixing surfaces 54U3 of the housing 54.

[0066] The reason why the pin fixing surface 54U3 is offset from the reference surface 54U1 in a direction away from the photosensitive drum 2 is to prevent interference with a separation mechanism (not shown) that separates the charging roller 3 from the photosensitive drum 2 inside the image forming apparatus 100. This separation mechanism prevents crushing of the charging roller side, which occurs when the photosensitive drum 2 and the charging roller 3 are in close contact with each other in the same phase when not driven, and prevents periodic density unevenness in the nip width of the photosensitive drum 2.

[0067] The housing 54 has pilot holes 54c and 54d for positioning pilot pins of a die when press-forming a metal plate. The pilot holes 54c and 54d are provided on a reference surface 54U1 of the housing 54 and are openings that communicate between the outside and the inside of the housing 54. In other words, the housing 54 has at least one opening (hole) that communicates between the outside and the inside of the housing 54, in addition to the first opening 54a and the second opening 54b.

[0068] Here, pilot holes 54c and 54d for positioning the pilot pins of the mold during press processing are shown as examples of holes that the housing 54 has, but this is not limited to these and the holes may be holes provided separately from the aforementioned pilot holes.

[0069] In press processing, it is preferable to make the reference surface 54U1 as wide as possible, and it is necessary to provide two pilot holes 54c and 54d on this reference surface 54U1 with as much space between them as possible. Therefore, in this embodiment, as shown in FIGS. 11 and 12, the pilot holes 54c and 54d are provided at both ends of the reference surface 54U1 of the housing 54 in the longitudinal direction. The pilot holes 54c and 54d are also provided outside the first opening 54a in the longitudinal direction of the reference surface 54U1 of the housing 54. The pilot holes 54c and 54d are also provided within the area of ​​the housing 54 sealed with the sealant 59.

[0070] The housing 54 also has a first pilot hole 54c and a second pilot hole 54d with a smaller diameter than the first hole. Here, the front pilot hole 54c has a diameter of φ5, and the rear pilot hole 54d has a diameter of φ4, which are different diameters. This prevents the pilot pin of the die from being attached backwards during press processing using the die.

[0071] Furthermore, the housing 54 is provided with sealing auxiliary members 74 on both longitudinal sides as abutting members that abut against the surfaces surrounding the pilot holes 54c, 54d of the housing 54. The sealing auxiliary members 74 have a contact surface that is larger than the surfaces of the pilot holes 54c, 54d of the housing 54. By abutting the sealing auxiliary members 74 against the surfaces surrounding the pilot holes 54c, 54d from below, the pilot holes 54c, 54d on both sides of the housing 54 are closed by the sealing auxiliary members 74.

[0072] Here, the material of the sealing auxiliary member 74 is a resin material (polycarbonate ABS) that has the properties of both PC (polycarbonate) and ABS. The sealing auxiliary member 74 is a component whose contact surface that contacts the surfaces surrounding the pilot holes 54c and 54d has a flatness of 0.1 mm and an arithmetic mean roughness of Ra 6.3. Note that the material of the sealing auxiliary member 74 and the flatness and roughness of the contact surface are examples and are not limited to these.

[0073] 11 and 12, the sealing auxiliary member 74 is fixed to the housing 54 with sealant 59 in a state where the sealing auxiliary member 74 is in contact with the surfaces around the lower holes of the pilot holes 54c and 54d of the housing 54. As a result, the pilot holes 54c and 54d of the housing 54 are blocked from below by the sealing auxiliary member 74.

[0074] 11 and 12, at both ends of the exposure head 4 in the longitudinal direction, the sealant 59 seals the gap between the sealing auxiliary member 74 and the substrate 50, and the gap between the sealing auxiliary member 74 and the housing 54.

[0075] 10, 11, and 12, except for the pilot holes 54c and 54d, the gap between the substrate 50 and the housing 54, the gap between the lens array 52 and the housing 54, and the gap between the sealing auxiliary member 74 and the housing 54 are all sealed with sealant 59. This prevents foreign matter from entering the optical path from the light-emitting elements to the lens array. The space from the light-emitting elements (LEDs 51) inside the exposure head 4 to the lens array 52, which is substantially sealed in this way, will hereinafter be referred to as the sealed space.

[0076] The pilot holes 54c and 54d of the housing 54 are configured to be approximately sealed by the abutment surface of the sealing auxiliary member 74, which has a rough surface, abutting against the surface around the hole from below, but are not completely sealed. Therefore, there is a possibility that an air current will be generated that passes longitudinally inside the sealed space of the exposure head 4, with the two pilot holes 54c and 54d as the inlet and outlet, respectively.

[0077] For this reason, in this embodiment, the boundary between the edge of the front pilot hole 54c, which has a relatively large diameter and is therefore more susceptible to foreign matter intrusion, and the sealing auxiliary member 74 is completely sealed with adhesive 58. In other words, by applying adhesive 58 to the entire periphery of the boundary between the abutting surface of the sealing auxiliary member 74, which abuts from below against the peripheral surface of one of the pilot holes 54c, and the edge of the one of the pilot holes 54c, one of the pilot holes 54c is completely sealed with adhesive 58.

[0078] Furthermore, adhesive 58 is applied around half the circumference of the boundary between the edge of the other pilot hole 54d and the contact surface of sealing assistant member 74, which is in contact with the peripheral surface of the other pilot hole 54d from below, so that the other pilot hole 54d is partially sealed with adhesive 58. In other words, pilot hole 54d has a portion (here, half the circumference) where adhesive 58 is not applied, and is not partially sealed.

[0079] In particular, the exposure head 4 is disposed with its optical axis direction tilted at a predetermined angle (15° in this case) with respect to a vertical line passing through the rotation center (axis) of the photosensitive drum 2 so that the emitted light strikes the surface of the photosensitive drum 2 perpendicularly. Therefore, it is conceivable that gravity may allow foreign matter to enter through the rear pilot hole 54d, which is substantially sealed. Therefore, when the exposure head 4 is disposed at an angle, half the circumference of the pilot hole 54d on the lower side is sealed with adhesive 58.

[0080] In this manner, the pilot holes 54c and 54d of the housing 54 are substantially sealed with the adhesive 58 serving as a sealant.

[0081] The above configuration prevents foreign matter from entering the sealed space from the light emitting elements (LEDs 51, LED chips 53) of the exposure head 4 to the lens array 52, while allowing gas such as outgassing of the sealant to be released to the outside.

[0082] Here, pilot holes 54c and 54d are sealed with adhesive 58 rather than sealant 59. This is because the area to be sealed is small and it is necessary to control and manage the shape of the adhesive, such as the viscosity and hardening time of the adhesive. For example, if a photo-hardening adhesive is used, it is easy to control and manage the shape of the adhesive by irradiating it with light immediately after application.

[0083] That is, the sealant that seals pilot holes 54c, 54d is adhesive 58. By applying adhesive 58 so as to bridge sealing auxiliary members 74 that abut the peripheral surfaces of each pilot hole 54c, 54d from below and the edges of each pilot hole 54c, 54d, the boundaries between sealing auxiliary members 74 and the edges of each pilot hole 54c, 54d are sealed.

[0084] Using the exposure head 4 configured as described above, an airflow simulation was performed to confirm whether particles with a particle size of 6.5 μm, which mimicked toner, would adhere from the pilot hole 54d onto the surface of the LED chip 53. The conditions for this simulation were as follows:

[0085] First, the airflow reproduced the flow of air in and out of pilot hole 54d, which occurs when the air in the sealed space of exposure head 4 heats up and expands, or cools down and contracts as the LED chip 53 is turned on and off. Furthermore, gap h (see FIG. 36) between the surface 54d1 surrounding the hole in housing 54 and the contact surface 74a of sealing auxiliary member 74 in pilot hole 54d was set to 200 μm, assuming the worst case scenario, based on the flatness of the surface surrounding the hole in housing 54 and the contact surface of sealing auxiliary member 74 that contacts it. FIG. 36 is a cross-sectional view of exposure head 4 taken at the portion of pilot hole 54d (indicated by the arrow in the figure) in FIG. 12.

[0086] Under the above conditions, we applied an initial velocity to the particles in a space with no flow field and confirmed how the particles would penetrate inside. As a result, we confirmed that no particles adhered to the surface of the LED chip 53, and that there was little possibility of particles penetrating into the sealed space through the gap h between the housing 54 and the sealing auxiliary member 74 at the pilot hole 54d.

[0087] We also conducted an actual measurement study to confirm whether foreign matter entered through the pilot hole 54d. In this study, we sprayed toner onto the pilot hole 54d and then repeatedly turned the LED chip 53 on and off to generate airflow through the pilot hole 54d. We confirmed whether toner entered the pilot hole 54d. The LED chip 53 was turned on and off for five minutes each, and this was repeated until the total lighting time reached 60 hours, taking into account the product's lifespan. Figure 37(a) shows the light intensity measurement data after the above study. Figure 37(b) shows a comparative example, showing light intensity data when a localized drop in light intensity occurred due to foreign matter. Figures 37(a) and 37(b) show excerpts from data for three LED chips 53-27, 53-28, and 53-29 located at the rear end of the pilot hole 54d. As shown in Figure 37(a), with the exposure head 4 configured as described above, the localized drop in light intensity shown in Figure 37(b) was not observed in the three LED chips 53-27, 53-28, and 53-29 closest to the pilot hole 54d. From these results, it was confirmed that with the exposure head 4 configured as described above, even under the harsh conditions of sprinkling minute particles such as toner into the pilot hole 54d as in this study, there was no effect on the light intensity after the study.

[0088] Furthermore, the surface roughness of the sealing auxiliary member 74 and the housing 54 was measured, and the arithmetic mean roughness was approximately Ra2.6 and Ra1.0, respectively, and it was confirmed that the total of 4σ was approximately Ra6.2, which is a very small gap. Note that, in the exposure head 4 manufactured with the configuration shown in this example, no phenomenon was observed in which the outgassing of the sealant 59 breaks through itself and is released to the outside.

[0089] From the results of the above simulations and actual measurements, it was confirmed that the simple configuration shown in this embodiment can prevent foreign matter from entering the sealed space of the exposure head 4 while releasing gases such as outgassing of the sealant to the outside.

[0090] (Housing support member) As shown in FIG. 6, the housing support member 55 supports the housing 54, which holds the substrate 50 and the lens array 52. ​​One and the other longitudinal ends of the housing support member 55 are fixed to the housing 54 by connecting members (not shown) such as an ultraviolet-curable 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 opposing the right side wall 55R across the housing 54, and a bottom surface portion 55D opposing the reference 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 and form a housing support member 55 that forms a duct serving as a flow path for airflow between the housing 54 and the bottom surface portion 55D. A plurality of openings 55a are provided in the bottom surface portion 55D of the housing support member 55 in the longitudinal direction, which is the axial direction of the photosensitive drum 2.

[0091] 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.

[0092] 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. 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 to separate the housing 54 and the drum unit 23.

[0093] 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. 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, which is 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.

[0094] 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.

[0095] 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 a duct between the housing 54 and the housing 55, which allows the airflow to circulate, and also forms part of a duct that cools the exposure head 4.

[0096] 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.

[0097] (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.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] 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 16). 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.

[0102] 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.

[0103] 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).

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] (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 15 and 16. Figure 15 is a cross-sectional view of the image forming apparatus taken along the line AA in Figure 1. Figure 16 is a perspective view of the duct unit as seen from above.

[0109] 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 .

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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.

[0114] (Cooling structure of exposure head) The cooling configuration of the exposure head will now be described with reference to Figures 10 to 13. In Figure 15, 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.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] 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. 8) 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. 16) of the duct unit 60 communicates with the other opening 69a (see FIG. 14) of the lifting duct 69.

[0119] 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. 15 ) 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.

[0120] 15 and 16, fan 67 located near the front of the device functions as an intake fan that takes in 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.

[0121] In the exposure cooling air flow indicated by the dashed lines in FIG. 15 , 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.

[0122] 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.

[0123] (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.

[0124] FIG. 17(a) is a diagram showing the longitudinal lengths of the sheet and opening of the exposure head according to Example 1. FIG. 17(b) is a top view of the exposure head according to Example 1. FIG. 18(a) is a cross-sectional view of the exposure head according to Example 1, taken along the line XX in FIG. 17(b). FIG. 18(b) is a cross-sectional view of the exposure head according to Example 1, taken along the line X'-X' in FIG. 17(b). FIG. 19 is a cross-sectional view of the exposure head according to Example 1, taken along the line YY in FIG. 17(b). FIGS. 20(a) and 20(b) are partial perspective views of the protrusions and elastic members of the housing support member according to Example 1, and FIG. 21 is a perspective view of the exposure head, lifting duct, and duct unit according to Example 1.

[0125] 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 through the space enclosed by the substrate 50, housing 54, and housing support member 55. However, a small gap exists between the housing 54 and housing support member 55. Specifically, a horizontal gap t1 exists in FIG. 18(a). At the longitudinal end of the exposure head 4, a horizontal gap t2 exists, and vertical gaps t3 and t4 exist in FIG. 18(b). These gaps are necessary from the perspective of exposure head assembly and component precision. From the perspective of assembly, if these gaps were not present, assembling the housing 54 and housing support member 55 vertically in FIG. 18(a) would require deformation of either or both of the housing 54 and housing support member 55. This could affect the optical system, such as the substrate 50 and the lens array 52. From the perspective of part precision, the housing 54 and housing support member 55 are long and narrow in the front-to-rear direction (axial direction) as a whole, and there is a risk of a certain amount of warping occurring during the part manufacturing process. From the above, it can be seen that a certain amount of gap is necessary between the housing 54 and housing support member 55 in order to accommodate dimensional tolerances including warping of the parts and assemble them without deformation. However, from the perspective of airflow to cool the exposure head 4, this gap is undesirable, and there is a risk of toner, tiny dust particles, etc. being scattered due to blowing or suction through the gap.

[0126] Therefore, in this embodiment, in order to reduce the scattering of foreign matter such as toner due to the outflow of airflow from the gap, the gaps t1 to t4 between the housing 54 and the housing support member 55 that constitute the exposure head 4 are sealed with a sealing member 71.

[0127] (Sealing with sheet material) First, the sealing of the gap t1 will be described. In this embodiment, as shown in Figure 18(a), the gap t1 between the housing 54 and housing support member 55 that constitute the exposure head 4 is sealed by a sealing member 71. Here, the sealing member 71 that seals the gap t1 is a sheet member. Hereinafter, the sealing member 71 will also be referred to as a sheet member 72.

[0128] The sealing member 71 seals the gap t1 between the substrate support portion of the housing 54 and the side wall of 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 18(a)) perpendicular to the optical axis direction and the axial direction.

[0129] 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 duct (space) between the housing 54 and the housing 54 to allow air to circulate.

[0130] 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.

[0131] The sealing member 71 seals the gap t1 between the one extension portion 54R and the right side wall 55R, which are opposed in the left-right direction, and the gap t1 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 t1 in the left-right direction between the housing 54 and the housing support member 55 shown in Figure 18(a), and can reduce the scattering of foreign matter such as toner due to the outflow of airflow.

[0132] 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. 8 and 17(a)). 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 in the axial direction from one end 71F to the other end 71B 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.

[0133] 21, 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.

[0134] Furthermore, one side of the sheet member 72 is attached and held to 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 t1, and abuts against the housing 54 due to the reaction force generated when the sheet member 72 is bent.

[0135] 18(a), the sheet member 72 is bent from the attachment portion 56 of the housing support member 55 and abuts against the housing 54. By bending the sheet member 72, the housing 54 that the sheet member 72 abuts against is configured to continuously receive the reaction force of the sheet member 72. This configuration 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 securely at the gap t1.

[0136] If the sheet member 72 is thin, it may bend or ripple when bent. On the other hand, if the sheet member 72 is thick, the reaction force that the housing 54 continuously receives increases, which may affect the optical system, such as the substrate 50 and lens array 52, held by the housing 54. Therefore, it is necessary to select an appropriate thickness for the sheet member 72.

[0137] In this embodiment, a polyester film having a thickness of 100 μm or less is used as 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.

[0138] Although the sheet member 72 has been described as being bent and inserted into the gap t1 and abutting against the housing 54, it may abut against both the housing 54 and the housing support member 55.

[0139] The housing support member 55 also 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, 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.

[0140] (Sealed by elastic material) Next, sealing of the gaps t2 to t4 will be described. In this embodiment, as shown in Figure 18(b), the gaps t2 to t4 between the housing 54 and housing support member 55 that constitute the exposure head 4 are sealed by a sealing member 71. Here, the sealing member 71 that seals the gaps t2 to t4 is an elastic member. Hereinafter, the sealing member 71 will also be referred to as an elastic member 73.

[0141] The housing support member 55 has protrusions 55b such as ribs that separate the duct (space) formed between it and the housing 54 into a duct portion that forms a flow path for airflow from one side of the substrate 50 to the other side in the longitudinal direction, and a non-duct portion that is on one side of the duct portion in the longitudinal direction.

[0142] Here, the duct portion is a region on the longitudinal rearward direction B side of the protrusion 55b, with the protrusion 55b as the boundary, such as the region La shown in Fig. 19. The non-duct portion is a region on the longitudinal forward direction F side of the protrusion 55b, with the protrusion 55b as the boundary, such as the region Lc on one side of the region La in the longitudinal direction shown in Fig. 17(a).

[0143] Housing support member 55 includes guide portions (right side wall 55R, left side wall 55L) that guide the airflow, which flows from the outside of housing support member 55 to the inside of housing support member 55 through opening 55a, in a direction from one side to the other in the longitudinal direction inside housing support member 55. Protrusion 55b is provided between right side wall 55R and left side wall 55L of housing support member 55. Protrusion 55b is provided on a portion (bottom surface portion 55D) of housing support member 55 that faces the back surface of substrate 50, and is provided upstream of opening 55a.

[0144] Furthermore, as shown in FIGS. 18(b) and 19, the exposure head 4 includes an elastic member 73 as the sealing member 71 that seals the gap between the duct portion and the non-duct portion.

[0145] The elastic member 73 is an elastic body having lower rigidity than the protrusion 55b of the housing support member 55. The elastic member 73 is, for example, a foam sealing material.

[0146] The elastic member 73 seals the gap t2 between the rear surface of the substrate 50 and the protrusion 55b between the duct portion and the non-duct portion.

[0147] The elastic member 73 seals the gap t2 between the protrusion 55b and the substrate support portion that supports one side and the other side of the substrate 50 in the short direction perpendicular to the longitudinal direction, between the duct portion and the non-duct portion.

[0148] The elastic member 73 seals the gap t4 between the duct portion and the non-duct portion, between the board support portion that supports one side and the other side of the board 50 in the short direction perpendicular to the longitudinal direction, and the housing support member 55.

[0149] In this embodiment, the elastic member 73 is adhesively fixed to the protrusion 55b of the housing support member 55 with double-sided tape (not shown). As shown in Figures 18(a) and 18(b), when the housing 54 that holds the substrate 50 is assembled to the housing support member 55, the elastic member 73 comes into contact with the housing 54 and the substrate 50 and elastically deforms, thereby sealing the gaps t2 to t4 described above. The elastic member 73 uses Eptsealer, a sealing material made by Nitto Denko Corporation, to reduce physical stress on the substrate 50, lens array 52, and housing 54.

[0150] 19, by providing the elastic member 73 on the upstream side of the cooling airflow inside the exposure head 4, it is possible to more efficiently prevent toner, fine dust particles, etc. from scattering due to air being blown out from the gaps t2-t3 between the duct portion and the non-duct portion. This is because the airflow generated by the duct unit 60 flows into the exposure head 4 from the upstream opening 55a of the housing support member 55, and the vicinity of the upstream opening 55a, which is blocked by the substrate 50, becomes relatively high pressure.

[0151] Furthermore, since the vicinity of the opening 55a downstream of the cooling air flow inside the exposure head 4 is forcibly exhausted by the fan 68, there is little possibility that unintended airflow will blow out from the gap between the housing 54 and the housing support member 55. However, to further reduce this, an elastic member 73 may also be provided downstream of the housing support member 55.

[0152] Furthermore, although the configuration in which housing support member 55 has protrusions 55b that separate the duct (space) formed between housing 54 and itself into a duct portion and a non-duct portion has been exemplified, the present invention is not limited to this, and the above-mentioned protrusions may not be provided. For example, a configuration in which elastic members 73 are provided to separate the duct (space) formed between housing 54 and itself into a duct portion and a non-duct portion, and gaps t2 to t3 between the duct portion and the non-duct portion are sealed by elastic members 73 may also be used.

[0153] (exposure head positioning) Next, the positioning of the exposure head 4 will be described with reference to Figures 22(a) and 22(b). Figure 22(a) is a perspective view seen from the front surface, cut in a direction perpendicular to the axial direction of the photosensitive drum 2 at the center positions of the positioning pins 54F and 54B. Figure 22(b) is a perspective view seen from the rear surface, cut in a direction perpendicular to the axial direction of the photosensitive drum 2 at the center positions of the positioning pins 54F and 54B.

[0154] (exposure head positioning pin) First, the positioning pins 54F and 54B of the exposure head 4 will be described.

[0155] The housing 54 of the exposure head 4 is provided with positioning pins 54F and 54B as positioning axes. Both the positioning pins 54F and 54B are examples of metal pins. The housing 54 is a conductive member having electrical conductivity, and the positioning pins 54F and 54B are also conductive members. The positioning pins 54F and 54B are fixed to both longitudinal end portions of the housing 54. The positioning pin 54F is fixed to the housing 54 on one side (front side) of the lens array 52 in the axial direction of the photosensitive drum 2, and protrudes from both sides of the housing 54 in the optical axis direction of the lens array 52. ​​The positioning pin 54B is fixed to the housing 54 on the other side (rear side) of the lens array 52 in the axial direction of the photosensitive drum 2, and protrudes from both sides of the housing 54 in the optical axis direction of the lens array 52.

[0156] In order to ensure with high precision the distance between the surface of the photosensitive drum 2 and the light emission surface of the lens array 52 of the exposure head 4, the position of the positioning surfaces at the ends of the shafts of the positioning pins 54F and 54B is adjusted using the housing 54 as a reference, and the positioning pins 54F and 54B are then caulked to the housing 54. Note that the method of fixing the positioning pins 54F and 54B to the housing 54 is not limited to this; for example, the metal positioning pins 54F and 54B may be fixed to the metal housing 54 by welding. In this way, the positioning pins 54F and 54B are integrated with the housing 54.

[0157] Then, the positioning pins 54F and 54B of the exposure head 4 abut against the drum bearing 26 of the drum unit 23. Specifically, in Figure 22(a), the front positioning pin 54F of the exposure head 4 abuts against the front drum bearing 26 of the photosensitive drum 2 at the end face of the positioning pin 54F. Also, in Figure 22(b), the rear positioning pin 54B of the exposure head 4 abuts against the rear drum bearing 26 of the photosensitive drum 2 at the end face of the positioning pin 54B. This determines the distance (gap) between the exposure head 4 and the photosensitive drum 2 in the direction perpendicular to the axial direction of the photosensitive drum 2, and determines the position of the exposure head 4 in the optical axis direction relative to the photosensitive drum 2.

[0158] Furthermore, positioning pins 54F and 54B fix not only the distance but also the angle of the exposure head 4 relative to the photosensitive drum 2. In the image forming apparatus 100, the exposure head 4 is arranged so as to point toward the center of the photosensitive drum 2. This arrangement is adopted because, due to the mechanism of the LEDs (light-emitting elements) 51 that the exposure head 4 has, it is not necessary to consider the influence of specular reflection on the surface of the photosensitive drum 2.

[0159] Furthermore, concave engaging portions 26F, 26B are integrally formed in each drum bearing 26 of the photosensitive drum 2 at positions facing the respective positioning pins 54F, 54B so that the engaging portions can engage with the tips of the positioning pins 54F, 54B. By machining the diameter of the tips of the positioning pins 54F, 54B and the width of the concave shape of the drum bearing 26 with high precision, positioning in a direction perpendicular to the optical axis direction of the exposure head 4 and a direction perpendicular to the axial direction of the photosensitive drum 2 is performed with high precision. Furthermore, a slope is formed at the entrance of the positioning pins 54F, 54B so that they do not ride up on the edge of the concave shape when engaging with the engaging portions 26F, 26B of the drum bearing 26.

[0160] In the axial direction of the photosensitive drum 2, the positioning pins 54F, 54B and the drum bearing 26 are not in contact with each other, and are positioned by a recessed regulating portion 75a (see FIG. 25) provided on the positioning member 75.

[0161] Here, the drum bearing 26 refers to a bearing member that supports the front and rear ends (both ends) of the photosensitive drum. By increasing the dimensional accuracy at the engagement points of this drum bearing 26, the photosensitive drum 2 is supported on the drum bearing 26 without any gaps. In other words, highly accurate positioning on the drum bearing 26 can be considered to be highly accurate positioning on the photosensitive drum 2. The photosensitive drum 2 is rotated during the image formation process. Therefore, the positioning pins 54F, 54B of the exposure head 4 are positioned relative to the drum bearing 26.

[0162] That is, the positioning pin 54F of the exposure head 4 is positioned with high precision relative to the drum bearing 26 on the front side of the image forming apparatus, and the positioning pin 54B of the exposure head 4 is also positioned with high precision relative to the drum bearing 26 on the rear side of the image forming apparatus. Therefore, the exposure head 4 is positioned with high precision at both ends of the photosensitive drum 2 in the axial direction.

[0163] 22(a) and 22(b), the positioning pins 54F, 54B are supplementarily fitted at their lower peripheral surfaces into the auxiliary fitting portions 30h, 30i of the cartridge tray 30 in a direction perpendicular to the optical axis direction of the exposure head 4 and in a direction perpendicular to the axial direction of the photosensitive drum 2. This ensures stable positioning accuracy in distance and angle, and repeated attachment and detachment operations, even when a slight rotational moment occurs due to the weight, surface properties, dimensional errors, etc. of the parts.

[0164] (exposure head positioning member) Next, the positioning of the exposure head 4 in the axial direction of the photosensitive drum 2 by the positioning member 75 will be described with reference to FIGS.

[0165] Fig. 23 is a perspective view of the positioning member 75 after it has been attached, and Fig. 24 is a perspective view of the positioning member 75 before it has been attached. Fig. 25 is a perspective view showing the shape of the positioning member 75.

[0166] 23, a positioning member 75 is attached to the front side of the exposure head 4 to position the exposure head 4 relative to the image forming apparatus 100. As shown in Fig. 24, a biasing portion 30d, a round hole portion 30e, a square hole portion 30f, and a claw engagement portion 30g are provided on the front side of the cartridge tray 30.

[0167] As shown in FIG. 25, the lower surface of the positioning member 75 is provided with a head regulating portion 75a, a biasing portion 75b, a cross-shaped protrusion 75c, an I-shaped protrusion 75d, and a claw portion 75e.

[0168] The outer diameter of the cross-shaped protrusion 75c is approximately equal to the inner diameter of the round hole 30e, and the left-right length of the I-shaped protrusion 75d is approximately equal to the left-right length of the square hole 30f. The position of the positioning member 75 in the front-rear and left-right directions is determined by fitting the respective protrusions 75c, 75d into the holes 30e, 30f.

[0169] The claw portion 75e has a barbed shape, and the barbed shape is caught on the claw engagement portion 30g, thereby determining the position of the positioning member 75 in the up-down direction.

[0170] In this way, the positioning member 75 is engaged with the cartridge tray 30, whereby the position of the positioning member 75 is determined relative to the cartridge tray 30 in the front-rear direction, the left-right direction, and the up-down direction.

[0171] The head regulating portion 75a has a first contact surface 75a1 that contacts one side of the positioning pin 54F in the axial direction and a second contact surface 75a2 that contacts the other side of the positioning pin 54F in the axial direction. The first contact surface 75a1 and the second contact surface 75a2 face each other in the axial direction. The head regulating portion 75a has a concave shape that is open on the right side in the left-right direction, and the notch width of the concave shape in the front-rear direction and the outer diameter of the positioning pin 54F are configured to be approximately equal. By fitting the head regulating portion 75a and the positioning pin 54F, the position of the exposure head 4 in the axial direction of the photosensitive drum 2 is determined relative to the positioning member 75.

[0172] In this way, the position of the exposure head 4 in the axial direction of the photosensitive drum 2 can be precisely determined by the positioning member 75 that is attached after the exposure head 4 is mounted.

[0173] In this embodiment, backlash is eliminated by the urging portion 75b and the urging portion 30d. The urging portion 75b extends to the right from the positioning member 75 and has a thin wall in the axial direction of the photosensitive drum 2, making it easy for the urging portion 75b to elastically deform in the axial direction of the photosensitive drum 2. On the other hand, the urging portion 30d protrudes from the upper surface of the cartridge tray 30 and is configured with a rigid shape that prevents it from deforming in the axial direction of the photosensitive drum 2. The dimensions are configured such that the tip of the urging portion 75b interferes with (contacts) the urging portion 30d when the positioning member 75 is attached to the cartridge tray 30. The front surface of the tip of the urging portion 75b comes into contact with the back surface of the urging portion 30d, causing the urging portion 75b to elastically deform in the rear direction. As a result, the reaction force urges the positioning member 75 in the rear direction, i.e., from one side to the other in the axial direction of the photosensitive drum 2.

[0174] In other words, the image forming apparatus 100 is provided with a biasing portion 30d as a biasing member that biases the exposure head 4 in the longitudinal direction. Here, as the biasing member, a configuration has been exemplified in which the cartridge tray 30, which is a support member that supports the photosensitive drum 2, has a biasing portion 30d that biases the positioning member 75 from one side to the other in the axial direction. That is, in this embodiment, a configuration is adopted in which the biasing portion 75b of the positioning member 75 is biased in the axial direction of the photosensitive drum 2 by the biasing portion 30d of the cartridge tray 30. However, the configuration is not limited to the above-mentioned configuration as long as it biases the exposure head 4 in the longitudinal direction.

[0175] By configuring the positioning member 75 in this way so that it is biased in the axial direction of the photosensitive drum 2, it is possible to achieve highly accurate positioning of the exposure head 4 that is less susceptible to the effects of repeated attachment and detachment of the exposure head 4, and it is possible to achieve even more precise positioning.

[0176] (Cleaning rod and cleaning rod guide configuration) Image forming apparatus 100 is provided with a longitudinal cleaning rod 81 that is inserted from the outside of image forming apparatus 100 and cleans light exit surface 52a of lens array 52 by rubbing it in the longitudinal direction. Image forming apparatus 100 also is provided with a first guide member 91 and a second guide member 92 that guide cleaning rod 81 that is inserted from the outside of image forming apparatus 100.

[0177] (Cleaning rod configuration) Next, the configuration of the cleaning rod 81 will be described.

[0178] In the image forming apparatus 100, the exposure head 4 is disposed between the charging roller 3 of the drum unit 23 and the developing unit 24. If toner or the like adheres to the light emitting surface of the lens array 52 provided in the exposure head 4, the adhered matter may partially block the light emitted from the light emitting elements, which is one cause of deterioration in the quality of the output image. For this reason, it is desirable to periodically clean the light emitting surface 52a of the exposure head 4.

[0179] The image forming apparatus 100 has a cleaning rod 81 that cleans the lens array 52 of the exposure head 4. The configuration of the cleaning rod 81 will be described with reference to Figures 26(a) to 26(c) and 27(a) to 27(b).

[0180] Figures 26(a) to 26(c) and Figures 27(a) to 27(b) are diagrams showing the configuration of a cleaning rod 81. Figure 26(a) is a schematic perspective view of the cleaning rod 81 that cleans the surface (light emission surface) of the lens array 52 of the exposure head 4. Figure 26(b) is a diagram showing one end (tip end) of the cleaning rod 81 in the longitudinal direction. Figure 26(c) is a diagram showing the tip end of the cleaning rod 81 as viewed from below. Figure 27(a) is a side view of the cleaning rod 81. Figure 27(b) is a bottom view of the cleaning rod 81.

[0181] Here, the longitudinal direction of the exposure head 4 is the direction along the rotation axis of the photosensitive drum 2 and is a direction parallel to the rotation axis. One side of the longitudinal direction of the exposure head 4 refers to the front side in the front-to-rear direction, and the other side of the longitudinal direction refers to the rear side in the front-to-rear direction. The width direction (short side direction) perpendicular to the longitudinal direction of the exposure head 4 is defined as the first direction. The optical axis direction perpendicular to both the longitudinal direction of the exposure head 4 and the width direction (first direction) perpendicular to the longitudinal direction is defined as the second direction. The defined longitudinal direction Y, width direction (first direction) X, and optical axis direction (second direction) Z are shown in Figures 26(a) to 26(c), 27(a) and 27(b), etc.

[0182] During cleaning operation, the longitudinal direction of the cleaning rod 81 is the Y direction, the lateral direction of the cleaning rod 81 is the X direction, and the insertion and removal direction of the cleaning rod 81 is the same as the Y direction.

[0183] The cleaning rod 81 cleans the lens array 52 of the exposure head 4. The cleaning rod 81 has an elongated rod shape as a whole, and is elongated in the longitudinal direction along the direction of the rotation axis of the photosensitive drum 2. The cleaning rod 81 has a cleaning member 83, a gripping portion 82, a protruding portion 86, an elastic portion 85, a guide member 87, a notched portion 88, and a wall 89.

[0184] Grip 82 is provided at the other end (rear end) of cleaning rod 81 in the longitudinal direction, and is the part that is gripped by the worker during cleaning.

[0185] Cleaning member 83 is provided at one end (tip) of cleaning rod 81 in the longitudinal direction, and comes into contact with light exit surface 52a of lens array 52 to clean off toner and other adhering matter adhering to light exit surface 52a of lens array 52. ​​Cleaning member 83 is provided below cleaning rod 81. Cleaning rod 81 cleans lens array 52 by moving cleaning member 83 in the longitudinal direction.

[0186] Here, the cleaning members 83 include two cleaning members 83a and 83b. The cleaning members 83a and 83b are arranged at different positions in the longitudinal direction of the exposure head 4. The cleaning members 83a and 83b are also arranged at different positions in the optical axis direction of the light exit surface of the exposure head 4. More specifically, the tips of the cleaning members 83a and 83b are also arranged at different positions in the optical axis direction relative to the light exit surface 52a of the exposure head 4. The number and arrangement of the cleaning members 83 are not limited to this, and for example, three or more cleaning members 83 may be arranged.

[0187] A pressing member 84 for fixing the cleaning member 83 is provided at the tip of the cleaning rod 81 in the longitudinal direction.

[0188] The cleaning rod 81 is provided with an elastic portion 85. Here, the elastic portion 85 is provided on one side of the cleaning rod 81 in the width direction. The elastic portion 85 has different rigidity in a first direction (width direction, X direction) and a second direction (optical axis direction, Z direction), with the rigidity in the width direction being lower than the rigidity in the optical axis direction. Specifically, the cross section of the elastic portion 85 viewed from the longitudinal direction is rectangular, and the thickness in the first direction (X direction) is thinner than the thickness in the second direction (Z direction). With this configuration, the rigidity of the elastic portion 85 in the width direction is lower than the rigidity in the optical axis direction.

[0189] The cleaning rod 81 is provided with a protruding portion 86 that protrudes from one side in the width direction. The protruding portion 86 is provided at a position that protrudes outward in the width direction beyond the first guide member 91 (see FIG. 29(b)) and can abut against the second guide member 92 (see FIG. 30(b)). The protruding portion 86 is provided so as to be movable between a position that protrudes outward in the width direction beyond the first guide member 91 and a position that is retracted toward the inside of the first guide member 91 in the width direction beyond the protruding position. The protruding portion 86 is guided by the second guide member 92 at the protruding position.

[0190] The protruding portion 86 is provided on the elastic portion 85, and moves in the width direction as a result of elastic deformation in the width direction of the elastic portion 85. In other words, the protruding portion 86 is provided so as to be movable in the width direction.

[0191] Further, the protrusion 86 is provided in the vicinity of the cleaning member 83. Here, the protrusion 86 is provided immediately after the cleaning member 83 in the longitudinal direction in the insertion direction (longitudinal direction, Y direction) of the cleaning rod 81.

[0192] Furthermore, cleaning rod 81 is provided with a guide member 87 that regulates the position of elastic portion 85 in the optical axis direction (second direction). Guide member 87 regulates deformation of elastic portion 85 due to unexpected external force in the optical axis direction within a predetermined range. Guide member 87 is made of a metal material, such as a metal plate.

[0193] The cleaning rod 81 has a cross-sectional shape including a facing portion 81U facing the light exit surface 52a of the lens array 52, and wall portions 81R and 81L extending from both sides of the facing portion 81U in a short direction perpendicular to the longitudinal direction toward the exposure head. The facing portion 81U supports the cleaning members 83 (83a and 83b). The wall portions 81R and 81L engage with the exposure head 4 along the longitudinal direction of the cleaning rod 81.

[0194] Cleaning rod 81 includes a first portion 81A having a first cross-sectional shape in a direction perpendicular to the longitudinal direction (Y direction) of cleaning rod 81, and a second portion 81B having a second cross-sectional shape different from that of first portion 81 A. Second portion 81B is provided at a different position in the longitudinal direction from first portion 81A.

[0195] The first cross-sectional shape of first portion 81A of cleaning rod 81 and the cross-sectional shape of second portion 81B of cleaning rod 81 differ as follows. This will be explained using Figures 32(a) to 32(b) and 35(a) to 35(b). Figures 32(a) and 32(b) are diagrams showing the shape of the notch according to Example 1. Figures 35(a) and 35(b) are diagrams showing the length relationship between the cleaning rod 81 and each portion of first guide member 91 according to Example 1.

[0196] The second cross-sectional shape of the second part 81B of the cleaning rod 81 is smaller in area than the first cross-sectional shape of the first part 81A of the cleaning rod 81. The second cross-sectional shape of the second part 81B of the cleaning rod 81 is shown in Fig. 32(b). The first cross-sectional shape of the first part 81A of the cleaning rod 81 is shown in Fig. 32(a).

[0197] Also, the second cross-sectional shape of the second part 81B of the cleaning rod 81 has a smaller width in the optical axis direction (Z direction) along the optical axis of the lens array 52 than the first cross-sectional shape of the first part 81A of the cleaning rod 81 (t6 < t5). The width t6 in the optical axis direction of the second cross-sectional shape of the second part 81B of the cleaning rod 81 is shown in Fig. 32(b). The width t5 in the optical axis direction of the first cross-sectional shape of the first part 81A of the cleaning rod 81 is shown in Fig. 32(a).

[0198] Also, the second cross-sectional shape of the second part 81B of the cleaning rod 81 has a smaller width in the short side direction (X direction) orthogonal to the longitudinal direction (Y direction) of the cleaning rod 81 than the first cross-sectional shape of the first part 81A of the cleaning rod 81 (t8 < t7). The width t8 in the short side direction of the second cross-sectional shape of the second part 81B of the cleaning rod 81 is shown in Fig. 32(b). The width t7 in the short side direction of the first cross-sectional shape of the first part 81A of the cleaning rod 81 is shown in Fig. 32(a).

[0199] Also, the cleaning rod 81 has a plurality of the second parts 81B in the longitudinal direction (Y direction). Here, a configuration in which the cleaning rod 81 has the second part 8(1)B at three locations in the longitudinal direction is illustrated, but it is not limited thereto.

[0200] [[ID=​​​​27(a) and 27(b), the walls 81R, 81L of the cleaning rod 81 are provided with cutouts 88. The portion of the cleaning rod 81 where the cutouts 88 are provided corresponds to the second portion 81B. The cutouts 88 are formed by thinning part of the walls 81R, 81L in the optical axis direction (Z direction) and the short side direction (X direction) of the cleaning rod 81. In other words, the second portion 81B of the cleaning rod 81 has a cross-sectional shape in which the walls 81R, 81L that engage with the exposure head 4 are shorter than the first portion 81A.

[0202] As a result, the second moment of area in the optical axis direction and the short-side direction of second portion 81B of cleaning rod 81 is smaller than that of first portion 81A of cleaning rod 81. Specifically, the second moment of area of ​​cleaning rod 81 at cutout portion 88 is 70% or less of the second moment of area of ​​cleaning rod 81 other than cutout portion 88. Therefore, by providing cutout portion 88, cleaning rod 81 has a shape with low rigidity in the optical axis direction and the short-side direction of cleaning rod 81.

[0203] In this embodiment, the second moment of area is reduced in both the optical axis direction and the short-side direction by the cutout portion 88, but the second moment of area may be reduced in only one of the directions. Therefore, the cleaning rod 81 has the cutout portion 88 so as to reduce the second moment of area in the direction perpendicular to the longitudinal direction (Y direction) of the cleaning rod 81.

[0204] As shown in FIG. 27(b), the cutout portion 88 is composed of six cutout portions 88a1, 88a2, 88b1, 88b2, 88c1, and 88c2. The cutout portions 88a1 and 88a2 are located at the same position in the longitudinal direction (Y direction) of the cleaning rod 81 and are opposed to each other in the lateral direction (X direction) of the cleaning rod 81. The cutout portions 88b1 and 88b2 are located at the same position in the longitudinal direction of the cleaning rod 81 and are opposed to each other in the lateral direction of the cleaning rod 81. The cutout portions 88c1 and 88c2 are located at the same position in the longitudinal direction of the cleaning rod 81 and are opposed to each other in the lateral direction of the cleaning rod 81. Therefore, the cleaning rod 81 has pairs of two cutout portions 88a, 88b, and 88c opposed to each other in the lateral direction.

[0205] Furthermore, cleaning rod 81 has two or more sets of cutouts 88 that face each other in the short side direction, along the length of cleaning rod 81. While in this embodiment six cutouts 88 are arranged, 88a1, 88a2, 88b1, 88b2, 88c1, and 88c2, the number of cutouts is not limited to this and may be five or fewer or seven or more. Furthermore, while in this embodiment two cutouts are arranged opposite each other in the short side direction of cleaning rod 81, the arrangement is not limited to this and the cutouts may be offset in the long side direction of cleaning rod 81.

[0206] The cleaning rod 81 has a wall 89 on the other end (rear end) in the longitudinal direction. When the cleaning rod 81 cleans the exposure head 4, the wall 89 comes into contact with a first guide member 91, thereby restricting the position of the cleaning rod 81 in the insertion direction (Y direction). The wall 89 is a stopper that restricts the amount of insertion of the cleaning rod 81 in the longitudinal direction so that the cleaning rod 81 is not inserted beyond a predetermined position. The aforementioned notch 88 is disposed between the wall 89 and the cleaning member 83 in the longitudinal direction of the cleaning rod 81.

[0207] (Cleaning rod guide configuration) Next, the guide structure for the cleaning rod 81 will be described.

[0208] The image forming apparatus 100 has a first guide member 91 and a second guide member 92 that guide the cleaning rod 81 that cleans the lens array 52 of the exposure head 4. The first guide member 91 and the second guide member 92 will be described with reference to Figures 28(a) to 28(c), 29(a) to 29(b), and 30(a) to 30(b).

[0209] Figures 28(a) to 28(c) are diagrams showing a guide configuration for a cleaning rod according to Example 1. Figures 29(a) and 29(b) are diagrams showing a configuration of a first guide member according to Example 1. Figures 30(a) and 30(b) are diagrams showing a configuration of a second guide member according to Example 1.

[0210] The image forming apparatus 100 has a frame (not shown) as a housing. As shown in Fig. 28(a), this frame is provided with a first guide member 91 and a second guide member 92. The first guide member 91 and the second guide member 92 are arranged offset from each other at the front and rear sides in the front-to-rear direction of the image forming apparatus 100, with the first guide member 91 arranged at the front side and the second guide member 92 arranged at the rear side.

[0211] The first guide member 91 is provided on an extension line of the lens array 52 in the longitudinal direction. The first guide member 91 is provided on the front side of the lens array 52 in the longitudinal direction, separately from the exposure head 4. The first guide member 91 guides the cleaning rod 81 between the photosensitive drum 2 and the exposure head 4.

[0212] The first guide member 91 has a cleaning rod restricting portion that restricts the position of the cleaning rod 81. Here, as shown in Fig. 28(b), the first guide member 91 has, as the cleaning rod restricting portion, first restricting portions 91a, 91a, second restricting portion 91b, and third restricting portion 91c.

[0213] The first guide member 91 has first restriction portions 91a that restrict the position of the cleaning rod 81 in a first direction (short-side direction, X direction). The first restriction portions 91a are provided on opposite sides in the width direction (X direction) that is perpendicular to the longitudinal direction. Movement of the cleaning rod 81 in the width direction is restricted between the first restriction portions 91a that are provided on opposite sides in the width direction.

[0214] The first guide member 91 has a second restricting portion 91b and a third restricting portion 91c that restrict the position of the cleaning rod 81 in a second direction (optical axis direction, Z direction). The second restricting portion 91b and the third restricting portion 91c are provided on opposite sides in the optical axis direction (Z direction). Movement of the cleaning rod 81 in the optical axis direction is restricted between the second restricting portion 91b and the third restricting portion 91c, which are provided on opposite sides in the optical axis direction.

[0215] The front end of second restricting portion 91b in the longitudinal direction is located further back in the longitudinal direction than the front ends of first restricting portion 91a and third restricting portion 91c in the longitudinal direction, thereby improving the operability of inserting cleaning rod 81 into first guide member 91.

[0216] The width of the cleaning rod 81 in the width direction (X direction) including the protrusion 86 is wider than the width of the inside of the first restriction portions 91a, 91a of the first guide member 91 in the width direction (X direction). As described above, the protrusion 86 is provided on the elastic portion 85 and is movable in the width direction (elastically deformable). When the protrusion 86 enters between the first restriction portions 91a, 91a of the first guide member 91, the elastic deformation of the elastic portion 85 causes the protrusion 86 to move from a position protruding beyond the width of the first guide member 91 to a retracted position toward the inside of the first guide member 91 in the width direction. Then, when the protrusion 86 passes through the first guide member 91, the restoring force of the elastic portion 85 causes the protrusion 86 to move from the retracted position to the protruding position, i.e., return to its original position where it can abut against the second guide member 92.

[0217] Furthermore, first guide member 91 has a contact portion 91d for stopping inserted cleaning rod 81 at a predetermined position. As a result, when cleaning rod 81 is inserted into first guide member 91, wall 89 of cleaning rod 81 abuts against contact portion 91d of first guide member 91, thereby restricting movement of cleaning rod 81 in the insertion direction and stopping it at a predetermined position.

[0218] Furthermore, the first guide member 91 has a head regulating portion 75a that regulates the position of the exposure head 4. The head regulating portion 75a regulates movement of the exposure head 4 in the longitudinal direction (Y direction) of the exposure head 4, which is the insertion direction of the cleaning rod 81. With this configuration, during cleaning, the exposure head 4 is regulated from moving backward in the insertion direction due to insertion of the cleaning rod 81.

[0219] In this embodiment, the positioning member 75 including the head regulating portion 75a is provided on the first guide member 91. In other words, the first guide member 91 also serves as the positioning member 75 that determines the longitudinal position of the exposure head 4 by coming into contact with the exposure head 4. Note that the first guide member 91 is not limited to a configuration that also serves as the positioning member 75, and the positioning member 75 may also be provided separately.

[0220] In this embodiment, as described above, backlash is eliminated by the urging portion 75b (see FIG. 25) and the urging portion 30d (see FIG. 24). The urging portion 75b extends rightward from the positioning member 75 and has a thin wall in the axial direction of the photosensitive drum 2, making it easy for the urging portion 75b to elastically deform in the axial direction of the photosensitive drum 2. On the other hand, the urging portion 30d protrudes from the upper surface of the cartridge tray 30 and is configured with a rigid shape that prevents deformation in the axial direction of the photosensitive drum 2. The dimensions are configured such that the tip of the urging portion 75b interferes with (comes into contact with) the urging portion 30d when the positioning member 75 is attached to the cartridge tray 30. The front surface of the tip of the urging portion 75b comes into contact with the back surface of the urging portion 30d, causing the urging portion 75b to elastically deform in the rear direction, and the resulting reaction force urges the positioning member 75 in the rear direction, i.e., from one side to the other in the axial direction of the photosensitive drum 2.

[0221] That is, the image forming apparatus 100 includes a biasing portion 30d as a biasing member that biases the exposure head 4 in the longitudinal direction. Here, the cartridge tray 30, which is a support member that supports the photosensitive drum 2, has the biasing portion 30d that biases the positioning member 75 from one side to the other in the axial direction. As a result, the first guide member 91, which also serves as the positioning member 75 including the biasing portion 75b, is biased from one side to the other in the axial direction by the biasing portion 30d of the cartridge tray 30.

[0222] As described above, the second guide member 92 is provided further back in the longitudinal direction than the first guide member 91. The second guide member 92 is provided separately from the exposure head 4, on the outside in the width direction (first direction) perpendicular to the longitudinal direction of the exposure head 4. The second guide member 92 guides the cleaning rod 81, which is guided between the photosensitive drum 2 and the exposure head 4, along the longitudinal direction of the exposure head 4.

[0223] 28(c), the second guide member 92 has a first guide portion (inclined portion) 92a and a second guide portion (restriction portion) 92b. The first guide portion 92a has an inclination that guides the cleaning rod 81 in a direction in the optical axis direction (Z direction) that brings the cleaning member 83 closer to the light exit surface of the lens array 52. ​​The first guide portion 92a is provided at the end of the second guide member 92 on the first guide member 91 side.

[0224] When the protrusion 86 of the cleaning rod 81 abuts against the first guide portion 92a, the first guide portion 92a guides the cleaning member 83 in a direction approaching the light exit surface of the lens array 52, and brings the cleaning member 83 into abutment against the light exit surface of the lens array 52.

[0225] The second guide portion 92b is provided further back in the longitudinal direction than the first guide portion 92a. The second guide portion 92b is provided in the longitudinal direction along the lens array 52. ​​When the protrusion 86 of the cleaning rod 81 abuts against the second guide portion 92b, the second guide portion 92b regulates the position in the optical axis direction (Z direction) of the cleaning member 83 abutting against the light exit surface of the lens array 52 across the longitudinal direction of the lens array 52.

[0226] The first guide portion 92a and the second guide portion 92b are provided on the outside in the width direction of the exposure head 4 and do not interfere with the movement of the exposure head 4 between the exposure position and the retracted position along the optical axis direction (Z direction). Furthermore, the protrusion 86 of the cleaning rod 81 protrudes outward in the width direction beyond the exposure head 4 and is provided in a position where it can abut against the second guide member 92 (see FIG. 30(b)). The first guide portion 92a and the second guide portion 92b abut against the protrusion 86 that protrudes outward in the width direction beyond the exposure head 4, thereby regulating the position of the cleaning member 83 in the optical axis direction, as described above.

[0227] (Cleaning operation) Next, the operation of cleaning the exposure head 4 using the cleaning rod 81 will be described.

[0228] As described above, the exposure head 4 is supported so as to be movable between an exposure position where it exposes the photosensitive drum 2 and a retracted position that is farther away from the photosensitive drum 2 than the exposure position. The exposure head 4 is moved between the exposure position and the retracted position along the optical axis direction by a movement mechanism.

[0229] Cleaning of the light exit surface of the lens array 52 using the cleaning rod 81 is performed with the exposure head 4 moved to a position retracted from the photosensitive drum 2 by the movement mechanism. In other words, the retracted position here refers to a cleaning position for cleaning the light exit surface of the lens array 52. ​​An operator cleans the light exit surface of the lens array 52 by gripping and operating the handle 82 provided on the rear end side of the cleaning rod 81.

[0230] 26(c), the cleaning member 83 is provided on the lower side of the tip end side of the cleaning rod 81 (the other end side in the direction of the rotation axis of the photosensitive drum 2). The cleaning member 83 is an elastically deformable member made of rubber such as sponge or elastomer, and scrapes off and cleans toner and other deposits adhering to the light-emitting surface of the lens array 52. ​​The cleaning member 83 is not limited to an elastically deformable member, and may be, for example, a nonwoven fabric made of fibers such as cotton, nylon, or polyester, which wipes off toner and other deposits adhering to the light-emitting surface of the lens array 52 for cleaning.

[0231] FIG. 29(a) shows a state in which the cleaning rod 81 is inserted into a first guide member 91 provided in the image forming apparatus 100. FIG. 29(b) is a diagram illustrating the function of the first guide member 91, as viewed from above the main body. The first guide member 91 is provided closer to the front of the apparatus main body than the exposure head 4. As shown in FIG. 29(b), the first guide member 91 has first restriction portions 91a, 91a on both sides in the first direction. The first guide member 91 also has a second restriction portion 91b (see FIG. 28(b)) and a third restriction portion 91c on both sides in the second direction. When an operator inserts the cleaning rod 81 between the first restriction portions 91a, 91a of the first guide member 91, the protrusion 86 abuts against one of the first restriction portions 91a while the lower position of the cleaning rod 81 in the second direction is restricted by the third restriction portion 91c. At this time, the width of cleaning rod 81, including protrusion 86, is wider in the first direction than the distance between first restriction portions 91a, 91a. Therefore, when cleaning rod 81 is further inserted, protrusion 86 retracts due to the elastic deformation of elastic portion 85 in the first direction and advances while abutting against first restriction portion 91a. This allows the operator to insert cleaning rod 81 while the position of cleaning rod 81 in the first direction is restricted by first guide member 91. Before the tip of cleaning rod 81 passes first guide member 92, the upper position of cleaning rod 81 in the second direction is restricted by second restriction portion 91b. After the tip of cleaning rod 81 passes first guide member 91, protrusion 86 is released from the restriction (abutment) by one of first restriction portions 91a, and returns to its position before elastic deformation due to the restoring force of elastic portion 85 in the first direction. That is, the protrusion 86 returns to a position where it can come into contact with the first guide portion 92a and the second guide portion 92b of the second guide member 92.

[0232] FIG. 30(a) shows the state immediately before the cleaning rod 81 is inserted into the second guide member 92 provided in the image forming apparatus 100. FIG. 30(b) is a cross-sectional view from the front of the main body, illustrating the function of the second guide member 92. The second guide member 92 is located further back than the first guide member 91. The second guide member 92 is also arranged longitudinally along the exposure head 4. A first guide portion 92a is provided at the end of the second guide member 92 facing the first guide member 91. As shown in FIG. 30(a), the first guide portion 92a slopes downward from the front end, which is one longitudinal end, to the rear end, which is the other longitudinal end, in order to guide the cleaning rod 81 in a direction in which the cleaning member 83 contacts the light-emitting surface of the lens array 52. ​​As a result, when an operator inserts the cleaning rod 81 into the second guide member 92, the first guide portion 92a guides the protrusion 86 to move downward. Therefore, the operator can more easily insert the cleaning rod 81 into the second guide member 92 without the protrusion 86 deviating above the second guide member 92. In other words, the cleaning rod 81 can be stably guided relative to the exposure head 4, improving the workability during cleaning. In addition, the cleaning member 83 reliably contacts the light exit surface of the lens array 52, enabling cleaning to begin.

[0233] As shown in FIG. 30(b), the second guide member 92 has a U-shaped cross section and includes a second guide portion 92b at the upper side in the second direction. When the cleaning member 83 cleans the light exit surface of the lens array 52, a repulsive force acts on the cleaning member 83 from the lens array 52, causing the tip side of the cleaning rod 81 to rise upward in the second direction. At this time, the position of the cleaning rod 81 in the second direction is restricted by a second restricting portion 91b (see FIG. 28(b)) provided on the first guide member 91. However, as the cleaning rod 81 is inserted further in, it moves away from the second restricting portion 91b, and therefore, the restriction by the second restricting portion 91b alone is insufficient.

[0234] Therefore, a protrusion 86 provided near the cleaning member 83 of the cleaning rod 81 abuts against a second guide portion 92b provided in the longitudinal direction along the exposure head 4. When the protrusion 86 of the cleaning rod 81 abuts against the second guide portion 92b of the second guide member 92, it can receive a repulsive force from the lens array 52, restricting the position of the tip side of the cleaning rod 81 in the second direction and preventing it from floating up at the rear side. This allows the cleaning rod 81 to be inserted all the way to the rear without the cleaning member 83 of the cleaning rod 81 separating from the light exit surface of the lens array 52, and enables the light exit surface of the lens array 52 to be reliably cleaned over the entire longitudinal direction.

[0235] Therefore, the first guide portion 92a of the second guide member 92 can stably guide the cleaning rod 81 (cleaning member 83) relative to the exposure head 4. The second guide portion 92b of the second guide member 92 can reliably clean the light exit surface of the lens array 52 of the exposure head 4.

[0236] Furthermore, by using the first guide member 91 and the second guide member 92 to regulate the position of the cleaning rod 81 during insertion and cleaning, even if the worker applies unexpected force, the cleaning member 83 will not move away from the light exit surface of the lens array 52, allowing for reliable cleaning.

[0237] Furthermore, by reducing the width (opening) between the first regulating portions 91a, 91a, space can be saved, and even if the distance between the photosensitive drums 2 of each color is narrow, the first guide member 91 can be arranged for each color. Furthermore, when an operator inserts the cleaning rod 81, it is possible to regulate vibration in the first direction.

[0238] (Positional relationship between cleaning parts and exposure head) Here, the positional relationship between the two cleaning members 83a and 83b of the cleaning rod 81 and the light exit surface of the exposure head 4 will be described in detail with reference to FIGS. 31(a) to 31(c).

[0239] As described above, the two cleaning members 83a and 83b of the cleaning rod 81 are arranged at different positions in the longitudinal direction of the exposure head 4. Furthermore, the tips of the two cleaning members 83a and 83b are arranged at different positions in the optical axis direction relative to the light exit surface 52a of the exposure head 4.

[0240] During cleaning, the cleaning rod 81 is inserted rearward toward the second guide member 92, which is provided further rearward than the first guide member 91, while its position in the second direction is restricted by the second restricting portion 91b and the third restricting portion 91c provided on the first guide member 91. Furthermore, after passing through the first guide member 91, the protruding portion 86 on the tip side of the cleaning rod 81 abuts against the second guide portion 92b provided on the second guide member 92, thereby preventing the tip of the cleaning rod 81 from lifting up. In other words, as the cleaning rod 81 is inserted rearward, the cleaning members 83a and 83b on the tip side are prevented from moving away from the light emission surface of the exposure head 4.

[0241] 31(a) is a cross-sectional view of cleaning members 83a and 83b near the tip of cleaning rod 81 just before protrusion 86 abuts on second guide portion 92b of second guide member 92. Cleaning members 83a and 83b are arranged on cleaning rod 81 at different positions in the optical axis direction of the light exit surface of exposure head 4.

[0242] 31(b) is a cross-sectional view of cleaning members 83a and 83b showing a state in which the tip of cleaning rod 81 is slightly raised. At this time, it can be seen that even if cleaning member 83b, which is positioned farther from the light exit surface of exposure head 4 in the optical axis direction, moves away from the light exit surface, cleaning member 83a, which is positioned closer to the light exit surface, does not move away from the light exit surface and can continue cleaning.

[0243] 31(c) is a cross-sectional view of cleaning members 83a and 83b showing a state in which the tip of cleaning rod 81 is slightly raised and lowered. In this state, cleaning member 83a, which is positioned closer to the light exit surface of exposure head 4 in the optical axis direction, has its side surface in contact with the light exit surface, which may result in areas not being wiped clean. However, cleaning member 83b, which is positioned farther from the light exit surface of exposure head 4, can be seen to be able to clean by having its tip in contact with the light exit surface.

[0244] (Cross-sectional shape of cleaning rod) 32(a) and 32(b), the shape of the notch 88 of the cleaning rod 81 will be described. In other words, the cross-sectional shapes of the first portion 81A and the second portion 81B of the cleaning rod 81 will be described.

[0245] Figures 32(a) and 32(b) are cross-sectional views of the cleaning rod 81 and exposure head 4 during cleaning operation, for explaining the shape of the cutout portion 88. Figure 32(a) is a cross-sectional view of a first portion 81A of the cleaning rod 81 other than the cutout portion 88. Figure 32(b) is a cross-sectional view of a second portion 81B of the cleaning rod 81, which is the portion of the cutout portion 88.

[0246] As shown in FIG. 32(a), during cleaning, the wall portions 81R, 81L of the cleaning rod 81 are arranged so that a first portion 81A other than the cutout portion 88 overlaps with the housing 54 of the exposure head 4 in the optical axis direction (Z direction). As described above, the operator can insert the cleaning rod 81 while restricting the position of the cleaning rod 81 in the first direction (X direction) using the first restricting portions 91a, 91a provided on the first guide member 91. However, if the operator inserts the cleaning rod 81 while applying force in the first direction, the restriction by the first restricting portion 91a alone becomes insufficient as the cleaning rod 81 is inserted further inward. Therefore, by overlapping the wall portions 81R, 81L of the cleaning rod 81 with the housing 54 of the exposure head 4 in the optical axis direction, the position of the tip of the cleaning rod 81 in the first direction is restricted, and the cleaning member 83 continues to contact the lens array 52. This allows the cleaning rod 81 to be inserted deep inside without the cleaning member 83 separating from the light exit surface of the lens array 52, and the light exit surface of the lens array 52 can be reliably cleaned over the entire longitudinal area.

[0247] 32(b), during cleaning, the walls 81R, 81L of the cleaning rod 81 are arranged so as not to overlap with the housing 54 of the exposure head 4 in the optical axis direction (Z direction) at the second portion 81B, which is the portion of the cutout portion 88. By arranging in this manner, the second moment of area in the optical axis direction (Z direction) and the short side direction (X direction) of the second portion 81B of the cleaning rod 81 is smaller than that of the first portion 81A, as described above, and the second portion 81B has a shape with low rigidity.

[0248] 32(a) and a second portion 81B having a second cross-sectional shape shown in FIG. 32(b), which is provided at a position different from the first portion 81A in the Y direction. The second cross-sectional shape of the second portion 81B of the cleaning rod 81 has an area smaller than the first cross-sectional shape of the first portion 81A of the cleaning rod 81.

[0249] Next, with reference to Figures 33(a) and 33(b), a case where an operator applies unexpected force to cleaning rod 81 during cleaning operation will be described.

[0250] 33(a) and 33(b) are diagrams showing a state in which an operator applies unexpected force to cleaning rod 81 during cleaning. Fig. 33(a) is a side view of cleaning rod 81 when force is applied in the optical axis direction (Z direction). Fig. 33(b) is a top view of cleaning rod 81 when force is applied in the short side direction (X direction).

[0251] As described above, the second cross-sectional shape of second portion 81B of cleaning rod 81 has a smaller area than the first cross-sectional shape of first portion 81A of cleaning rod 81. In other words, by providing cutout portion 88, cleaning rod 81 has a small moment of inertia in the optical axis direction and the short side direction, resulting in a shape with low rigidity.

[0252] More specifically, as shown in FIGS. 32(a) and 32(b), the cleaning rod 81 has a shape in which the width t6 of the second cross-sectional shape of the second portion 81B in the optical axis direction is smaller than the width t5 of the first cross-sectional shape of the first portion 81A of the cleaning rod 81 in the optical axis direction.

[0253] Therefore, if an operator applies an unexpected force to cleaning rod 81 in the optical axis direction, cleaning rod 81 will bend in the optical axis direction on the near side of first guide member 91, as shown in Figure 33(a). Because the operator is working while holding grip portion 82, grip portion 82 is displaced significantly in the optical axis direction, making it easy for the operator to recognize that an unexpected action is being performed. Furthermore, cleaning rod 81 that has been displaced significantly can come into contact with a cover or the like (not shown) of image forming apparatus 100, thereby functioning as a stopper to prevent further unexpected force from being applied.

[0254] Furthermore, as shown in Figures 32(a) and 32(b), the cleaning rod 81 has a shape in which the width t8 in the short direction of the second cross-sectional shape of the second part 81B is smaller than the width t7 in the short direction of the first cross-sectional shape of the first part 81A of the cleaning rod 81.

[0255] Therefore, if an operator applies an unexpected force to cleaning rod 81 in the short-side direction, cleaning rod 81 will bend in the short-side direction on the near side of first guide member 91, as shown in Figure 33(b). Because the operator is working while holding grip portion 82, grip portion 82 is displaced significantly in the short-side direction, making it easy for the operator to recognize that an unexpected action is occurring, just as when cleaning rod 81 is displaced in the optical axis direction. Furthermore, if cleaning rod 81 is displaced significantly, it can come into contact with a cover (not shown) of image forming apparatus 100 or the like, thereby acting as a stopper to prevent further unexpected force from being applied.

[0256] In this way, even if an operator applies an unexpected force to cleaning rod 81 during cleaning, cleaning rod 81 will bend in the direction of the applied force on the front side of first guide member 91. Therefore, the tip of cleaning rod 81, whose position is restricted on the rear side of first guide member 91 and second guide member 92, will not move away from exposure head 4, allowing for reliable cleaning.

[0257] (Cleaning rod stopper) 34(a) and 34(b) are diagrams showing the state in which the cleaning rod 81 is inserted deep into the main body of the image forming apparatus 100, with FIG. 34(a) being a schematic perspective view of the cleaning rod 81 and the first guide member 91, and FIG. 34(b) being a cross-sectional view of the tip of the cleaning rod 81 and the exposure head 4.

[0258] As shown in FIG. 34(a), when an operator inserts cleaning rod 81 to the rear of image forming apparatus 100, wall 89 of cleaning rod 81 abuts against abutment portion 91d of first guide member 91, restricting the position of cleaning rod 81 and preventing further insertion. At this time, as shown in FIG. 34(b), both cleaning members 83a and 83b have passed the rear end of lens array 52. ​​That is, wall 89 (or the abutment portion of first guide member 91) is positioned so that cleaning rod 81 is restricted in position by first guide member 91 when cleaning members 83a and 83b at their respective tips have passed the rear end of lens array 52. ​​This positioning allows deposits removed by cleaning member 83 from lens array 52 to be moved to the outside of lens array 52.

[0259] (Dimensional relationship between the cleaning rod and the first guide member) Next, the dimensional relationship between the various parts of the cleaning rod 81 and the first guide member 91 will be described in detail with reference to Figures 35(a) and 35(b).

[0260] Figures 35(a) and 35(b) are diagrams showing the dimensional relationship between the cleaning rod 81 and the first guide member 91, with Figure 35(a) being a side view in the state shown in Figure 34(a) and Figure 35(b) being a top view of the first guide member 91.

[0261] 35(a), cleaning rod 81 has cutouts 88 (88a, 88b, 88c) at multiple locations in the longitudinal direction (Y direction). In other words, cleaning rod 81 has multiple second portions 81B in the longitudinal direction (Y direction). Here, the distance between cutouts 88a and 88b and the distance between cutouts 88b and 88c in the longitudinal direction of cleaning rod 81 are denoted by Lp, and the distance between wall 89 of cleaning rod 81 and the cutout 88c closest to wall 89 is denoted by Lr.

[0262] Also, as shown in Figure 35(b), the length of the first regulating portion 91a in the longitudinal direction (Y direction) of the first guide member 91 is the longitudinal guide length Ly, and the length from the second regulating portion 91b to the third regulating portion 91c is the optical axis direction guide length Lz.

[0263] At this time, the following dimensional relationship (1) holds between the cleaning rod 81 and the first guide member 91.

[0264] Lp>Ly and Lp>Lz (1)

[0265] In this embodiment, the distance between adjacent notches in the longitudinal direction of the cleaning rod 81 is set to Lp, but the distance between any two notches may be longer than the guide length of the first guide member 91. For example, the distance Lp' between the notches 88a and 88c may satisfy the following dimensional relationship (2):

[0266] Lp′>Ly and Lp′>Lz (2)

[0267] The first guide member 91 is rigid, and while guiding the cleaning rod 81, the guide length Ly, which is the region where the cleaning rod 81 engages with the first guide member 91, is substantially rigid. In other words, if all of the notches 88 of the cleaning rod 81 are included within the guide length Ly, which is the region where the first guide member 91 engages with the cleaning rod 81, the cleaning rod 81 cannot deform due to the notches 88c2...notches. As a result, when an operator applies an unexpected force to the cleaning rod 81, the amount of displacement of the cleaning rod 81 is reduced, and the effect of notifying the operator that an unexpected force has been applied as described above is not achieved. Therefore, adjacent notches 88 are spaced apart in the longitudinal direction so that the distance Lp between at least two pairs of notches 88 is longer than the guide lengths Ly and Lz of the first guide member 91 in the longitudinal direction. In other words, adjacent notches 88 are spaced apart in the longitudinal direction so that the dimensional relationship (1) is satisfied.

[0268] Furthermore, the guide length Ly and the guide length Lz of the first guide member 91 satisfy the following dimensional relationship (3).

[0269] Lr>Lz (3)

[0270] There is a small gap between the first guide member 91 and the cleaning rod 81, allowing the cleaning rod 81 to displace by the amount of the gap. The wall 89 provided on the cleaning rod 81 extends in the optical axis direction and contacts the first guide member 91 to regulate the position of the cleaning rod 81. However, if the notch 88 is located near the wall 89, the cleaning rod 81 becomes deformable within the small gap in the first guide member 91, and the contact portion 91d of the wall 89 and the first guide member 91 do not contact each other. As a result, the cleaning rod 81 is not restricted by the first guide member 91 and may be inserted further than the predetermined position within the image forming apparatus 100. Therefore, the distance Lr between the wall 89 and the notch 88 of the cleaning rod 81 is set to be greater than the guide portion length Lz of the first guide member 91. In this embodiment, the wall 89 provided on the cleaning rod 81 is arranged to extend in the optical axis direction and is configured to abut against the first guide member 91, so the relationship between the gap Lr and the optical axis direction guide length Lz must satisfy the above dimensional relationship (3).

[0271] However, this relationship is not limited to this. For example, if the wall 89 provided on the cleaning rod 81 is arranged to extend in the short-side direction, the relationship between the spacing Lr and the short-side guide length Ly may be such that the following dimensional relationship (4) holds.

[0272] Lr>Ly (4)

[0273] Therefore, the distance Lr between the wall 89 of the cleaning rod 81 and the notch 88c is greater than the length Ly or Lz of the guide portion of the first guide member 91.

[0274] With the above configuration, even if an operator applies unexpected force when inserting the cleaning rod 81 into the image forming device 100, the cleaning rod 81 can be inserted stably, and the exposure head 4 can be cleaned stably and reliably.

[0275] Other Examples In the above-described embodiment, a tandem-intermediate transfer type four-color full-color printer has been described as an example, but for example, a direct transfer type in which a toner image is transferred from the photosensitive drum 2 to the recording paper P without using the intermediate transfer belt 9 may be used. Furthermore, the printer may be a single-color monochrome printer, or a full-color printer with five or more colors using special color toner. In that case, a configuration may be used in which a number of exposure heads 4 corresponding to the number of colors are provided.

[0276] The up-down direction of the units and parts has been described in accordance with the arrangement of each unit in the cross-sectional view of the image forming apparatus 100 shown in Fig. 1. However, the units may be arranged such that the photosensitive drum 2 is arranged above the intermediate transfer belt 9 and the exposure head 4 is further arranged above that, such as in a top exposure method in which the photosensitive drum 2 is exposed from approximately above. In that case, the up-down directions in the description of the embodiments are all reversed.

[0277] Furthermore, in the above-described embodiment, the holding member for holding the substrate and the lens array is exemplified as a housing 54 made of electrogalvanized steel sheet manufactured by press working and having pilot holes, but the material and manufacturing method of the holding member are not limited to this. The housing 54 only needs to have one or more holes that form a minute gap at the boundary with the abutting sealing auxiliary member 74, and may be made of pressed stainless steel sheet metal, molded resin material such as LCP, or die-cast aluminum material, depending on the performance required of the exposure head 4. When the housing (holding member) is manufactured by molding or die-casting, there is an advantage in that there is greater design freedom in terms of the shape and the arrangement of the aforementioned holes than when sheet metal is pressed.

[0278] Similarly, the material of the sealing auxiliary member 74 is not limited to the configuration shown in the above-described embodiment. The sealing auxiliary member 74 may be made of a metal such as aluminum, or a resin material different from that used in the embodiment, such as LCP, as long as it can abut against and cover the periphery of the hole provided in the housing 54. If the sealing auxiliary member 74 is made of a metal, it has the advantage of excellent heat dissipation due to its high thermal conductivity. Furthermore, if the hole provided in the housing 54 is small or the adhesive 58 has high viscosity, it is not necessary to use the sealing auxiliary member 74, and the hole in the housing 54 may be sealed using only the adhesive 58.

[0279] Furthermore, in the above-described embodiment, a pilot hole that occurs due to manufacturing reasons for the housing 54 is utilized, but a hole shape may be intentionally formed in the housing 54 in addition to the pilot hole. For example, if a hole can be formed for the purpose of forming a gap on the side of the housing on the drum unit side that is farther away from the photosensitive drum 2 and the developing unit 24, the possibility of toner entering the sealed space of the exposure head 4 can be reduced.

[0280] In the above-described embodiment, pilot holes generated during the manufacturing process of the housing 54 were utilized as holes in the housing 54. However, the purpose, shape, and location of the holes in the housing 54 are not limited to those described in the above-described embodiment. For example, holes other than pilot holes may be intentionally provided in the housing 54, such as holes for cleaning the interior at the end of the exposure head manufacturing process, holes for fixing the exposure head to the manufacturing equipment, or holes for irradiating UV light to harden the adhesive. Alternatively, holes may be provided on the side of the housing 54 on the drum unit side, away from the photosensitive drum 2 and the development unit 24, to form a gap. This configuration reduces the possibility of toner entering the sealed space of the exposure head 4. Furthermore, the shape of the holes is not limited to circular holes, and the location of the holes is not limited to the top surface (reference surface) of the housing 54. For example, rectangular holes may be provided on the side of the housing 54 (substrate support portion) to fix the substrate 50 to the housing 54.

[0281] The sealant 59 and adhesive 58 may be different materials as in the above-described embodiment, or the same material may be used, or multiple types may be used. For example, the material may be acrylic, silicone, epoxy, etc., and the curing type may be photocurable, thermosetting, moisture curable, anaerobic curable, etc., and may be selected appropriately depending on the performance of the exposure head 4 and manufacturing convenience.

[0282] In the above-described embodiment, the sealing member 71 is the sheet member 72, but the present invention is not limited to this, and the sealing member 71 may be a filler (sealant). The gap t1 (see FIG. 18(a)) between the housing support member 55 and the housing 54 may be filled with a moisture-curing silicone resin as a filler to seal the gap t1. The filler (sealant) 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.

[0283] In the above-described embodiment, a configuration in which a duct formed between the housing support member 55 and the housing 54 is separated into a duct portion and a non-duct portion by providing a protrusion 55b and the gap is sealed with an elastic member 73 has been described as an example. However, the present invention is not limited to this. For example, a configuration in which a duct formed between the housing support member 55 and the housing 54 is separated into a duct portion and a non-duct portion by providing a protrusion 55b and the gap is sealed with a sealant may be used. Alternatively, a configuration in which a sealant is provided to separate the duct formed between the housing support member 55 and the housing 54 into a duct portion and a non-duct portion, and the gap between the duct portion and the non-duct portion is sealed with the sealant may be used. The sealant may be a moisture-curing silicone resin similar to the sealant 59 that seals the gap between the housing 54 and the lens array 52 and the gap between the housing 54 and the substrate 50. Alternatively, the sealant is not limited to a moisture-curing resin and may be, for example, a photo-curing adhesive or a foam sealant. [Explanation of symbols]

[0284] La...range Ls...length h, t1~t8 ... gap 1...Image forming unit 2...Photosensitive drum 4...Exposure head 23...Drum unit 24...Developing unit 30...Cartridge tray 30d...Biasing part 50...Substrate 51...LED 52...Lens array 52a...Light exit surface 52b...Light incidence surface 53...LED chip 54...Case 54F, 54B ... Positioning pin 54L,54R…extension part 54U…Reference part 54U1...Reference surface 54U2 ...Jockle shape 54U3 ... Pin fixing surface 54a...1st opening 54b…Second opening 54c, 54d ... Pilot holes 54d1...plane 55...Housing support member 55D…Bottom part 55L…Left side wall 55R…Right side wall 55a...Aperture 55b…protrusion 56 ...Attachment part 57...Connector 58...adhesive 59...Sealant 60...Duct unit 60a...opening 71...Sealing member 72 ... Sheet member 73...Elastic member 74...Sealing auxiliary member 74a…Abutment surface 75... Positioning member 75a...Head regulation part 75b ... biasing part 81…Cleaning rod 81A…Part 1 81B…Second part 81R,81L…Wall part 81U...opposing part 82...gripping part 83, 83a, 83b ... cleaning materials 84 ...Pressing member 85...Elastic part 86...Protrusion 87 ... Guide member 88, 88a, 88b, 88c ...Notch 88a1, 88a2, 88b1, 88b2, 88c1, 88c2 ...Notch 89...wall 91 ... First guide member 91a...First Regulatory Section 91b...Second Regulatory Department 91c ... Third Regulatory Division 91d...Abutting part 92 ... second guide member 92a ... First guide section 92b...Second guide section 100...Image forming device

Claims

1. A photoreceptor; an exposure head that exposes the photosensitive member, the exposure head including a substrate on which a plurality of light-emitting elements are mounted along a longitudinal direction that is the axial direction of the photosensitive member, and a lens array that includes a plurality of lenses that focus light emitted from the light-emitting elements onto the photosensitive member; a cleaning rod having a longitudinal shape that is inserted from the outside of the image forming apparatus and cleans the light exit surface of the lens by rubbing it in the longitudinal direction; a guide member for guiding a cleaning rod inserted from the outside of the image forming apparatus, The cleaning rod is a cleaning member that comes into contact with the light exit surface of the lens to clean deposits adhering to the light exit surface of the lens; a first portion having a first cross-sectional shape in a direction perpendicular to the longitudinal direction; a second portion provided at a position different from the first portion in the longitudinal direction and having a second cross-sectional shape different from that of the first portion, An image forming apparatus characterized by:

2. The second cross-sectional shape has an area smaller than that of the first cross-sectional shape.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

3. the second cross-sectional shape has a smaller width in the optical axis direction along the optical axis of the lens than the first cross-sectional shape; 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

4. the second cross-sectional shape has a smaller width in a lateral direction perpendicular to the longitudinal direction of the substrate than the first cross-sectional shape; 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

5. The second portion has a smaller moment of inertia than the first portion.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

6. The cleaning rod has a plurality of the second portions.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

7. The guide member has a length in a longitudinal direction, The first portion of the cleaning rod has a longitudinal length longer than that of the guide member.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

8. The cleaning rod has a wall portion that engages with the exposure head along the longitudinal direction.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

9. The wall portion of the second portion is shorter than that of the first portion (cutout), 9. The image forming apparatus according to claim 8,

10. The cleaning rod is a facing portion that faces the light exit surface of the lens and supports the cleaning member; a wall portion extending from both sides of the opposing portion in a lateral direction perpendicular to the longitudinal direction toward the exposure head and engaging with the exposure head; the first portion has the first cross-sectional shape including the opposing portion and the wall portion, The second portion has the second cross-sectional shape including at least the facing portion.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

11. 2. The image forming apparatus according to claim 1, wherein the light emitting element is an organic electroluminescent element.

Images