Optical print head and image forming apparatus

Abstract

To suppress inflow of a sealing material to an LED array mounted on a substrate.SOLUTION: An optical print head comprises: a substrate which is mounted with a plurality of light-emitting elements; a lens which condenses light emitted from the light-emitting elements to a photoreceptor; a holding member which holds the substrate and the lens; and an attachment part which is provided in the holding member, is provided on the outer side with respect to the end of the substrate in the longitudinal direction of the substrate and is attached with a movement mechanism that moves the holding member between an exposure position for exposing the photoreceptor and a separation position farther apart from the photoreceptor than the exposure position. A wall part is provided between the end of the substrate and the attachment part in the longitudinal direction and the sealing material is applied so as to contact the substrate and the wall part.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an optical print head that exposes a photoconductor, and to an electrophotographic image forming apparatus, such as a digital copying machine or a facsimile machine, that is provided with the optical print head. [Background technology]

[0002] Conventionally, a widely used electrophotographic image forming device uses an exposure device equipped with an LED array and a lens array to form an electrostatic latent image on the surface of a photoconductor, and then develops the toner image by attaching toner to the electrostatic latent image.

[0003] In this exposure device, if foreign matter such as toner gets into the space around the LED array and the lens array, problems such as a decrease in the amount of light may occur. To address this issue, a technique described in Patent Document 1 is known.

[0004] In the exposure device described in Patent Document 1, a sealant is applied to the gap between a base that holds a substrate on which an LED array is mounted and a U-shaped steel holder, and shielding plates are provided at both longitudinal ends of the base, thus preventing the intrusion of foreign matter from the gap between the base and the holder and from both ends of the holder. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2012-66499 A [Patent Document 2] Patent Publication No. 2021-74943 Summary of the Invention [Problem to be solved by the invention]

[0006] However, with the technology of Patent Document 1, it is difficult to dispose the shielding plates at both longitudinal ends of the base without leaving any gaps between the base and the holder, and the sealing performance is not sufficient.

[0007] On the other hand, in the technology of Patent Document 2, the substrate on which the LED array is mounted is directly held by a U-shaped holder made of a steel plate, and a sealant is applied to the gap between the substrate and the holder. Therefore, it is considered to seal the substrate end with a sealant to prevent foreign matter from entering from the longitudinal end of the substrate. However, since there is no wall, if foreign matter is tried to seal the substrate end with a sealant, there is a risk that the sealant will flow into the LED array mounted on the substrate before the sealant hardens.

[0008] An object of the present invention is to prevent the inflow of encapsulant into an LED array mounted on a substrate. [Means for solving the problem]

[0009] A representative configuration of the present invention for achieving the above object includes a substrate on which a plurality of light-emitting elements are mounted, a lens that focuses light emitted from the light-emitting elements onto a photosensitive member, a base portion that holds the substrate and the lens and has an opening into which the lens is inserted, a first extension portion that extends from one side in a lateral direction perpendicular to the longitudinal direction of the substrate in a direction away from the photosensitive member, and a second extension portion that extends from the other side in the lateral direction in a direction away from the photosensitive member, forming a U-shape, the lens inserted into the opening being held by the base portion, and the substrate being held by the first extension portion and the second extension portion, and At a distance from the end a wall portion disposed on the substrate and facing a surface of the substrate intersecting the longitudinal direction, the wall portion having a shape along an inner surface of a U-shape formed by the base portion, the first extension portion, and the second extension portion; In the longitudinal direction The substrate and the wall Seal the gap and a sealing material. Effect of the Invention

[0010] According to the present invention, it is possible to suppress the inflow of the sealing material into the light emitting element mounted on the substrate, and also to further reduce the intrusion of foreign matter by sealing the end of the substrate in the longitudinal direction with the wall portion and the sealing material. [Brief description of the drawings]

[0011] [Figure 1] Cross-sectional view of an image forming apparatus [Diagram 2] Perspective view of an optical print head [Diagram 3] (a)(b)(c)(d)(e) Illustration of the substrate and lens array [Figure 4] Side view of optical print head [Diagram 5] Side view of optical print head [Figure 6] Perspective view of the substrate [Figure 7] Perspective view of an optical print head [Figure 8] A cross-sectional perspective view of an optical print head. [Figure 9] A cross-sectional perspective view of an optical print head. [Figure 10] A cross-sectional perspective view of an optical print head. [Figure 11] A cross-sectional perspective view of an optical print head. [Figure 12] A cross-sectional perspective view of an optical print head. [Figure 13] FIG. 1 is a perspective view showing a portion of an optical print head. [Figure 14] FIG. 1 is a perspective view showing a portion of an optical print head. [Figure 15] Perspective view of an optical print head [Figure 16] A cross-sectional perspective view of an optical print head. [Figure 17] A cross-sectional perspective view of an optical print head. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0013] Example 1 (Image forming device) First, a schematic configuration of the image forming apparatus 1 will be described. Fig. 1 is a schematic cross-sectional view of the image forming apparatus 1. The image forming apparatus 1 shown in Fig. 1 is a color printer (MFP: Multi Function Printer) equipped with a reading device, but the embodiment may be a copier that does not have a reading device. Furthermore, the embodiment is not limited to a so-called tandem type color image forming apparatus equipped with a plurality of photosensitive drums 103 as shown in Fig. 1, but may be a color image forming apparatus equipped with one photosensitive drum 103 or an image forming apparatus that forms a monochrome image.

[0014] The image forming apparatus 1 shown in Fig. 1 includes four image forming units 102Y, 102M, 102C, and 102K (hereinafter collectively referred to simply as "image forming unit 102") that form toner images of the respective colors of yellow, magenta, cyan, and black. The image forming units 102Y, 102M, 102C, and 102K also include photosensitive drums 103Y, 103M, 103C, and 103K (hereinafter collectively referred to simply as "photosensitive drum 103") as photosensitive bodies (image carriers). These photosensitive drums are arranged at a distance from each other. The image forming units 102Y, 102M, 102C, and 102K are also provided with chargers 104Y, 104M, 104C, and 104K (hereinafter collectively referred to as "charger 104") as charging means for charging the photosensitive drums 103Y, 103M, 103C, and 103K, respectively. The image forming units 102Y, 102M, 102C, and 102K are also provided with LED (Light Emitting Diode, hereinafter referred to as LED) exposure units 500Y, 500M, 500C, and 500K (hereinafter collectively referred to as "exposure unit 500") as exposure light sources for emitting light for exposing the photosensitive drums 103Y, 103M, 103C, and 103K. Furthermore, the image forming units 102Y, 102M, 102C, and 102K each include developing units 106Y, 106M, 106C, and 106K (hereinafter collectively referred to as "developing units 106") that develop the electrostatic latent image on the photosensitive drum 103 with toner and develop a toner image of each color on the photosensitive drum 103. The letters Y, M, C, and K attached to the reference characters indicate the colors of the toner.

[0015] The image forming apparatus 1 shown in FIG. 1(a) is an image forming apparatus that employs a so-called "bottom surface exposure method" in which a photosensitive drum 103 is exposed from below. The following description will be given on the premise that the image forming apparatus employs the bottom surface exposure method. Note that, although not shown in the drawings, an embodiment may also be an image forming apparatus that employs an "top surface exposure method" in which a photosensitive drum is exposed from above.

[0016] The image forming apparatus 1 includes an intermediate transfer belt 107 onto which a toner image formed on a photosensitive drum 103 is transferred, and primary transfer rollers 108 (Y, M, C, K) that sequentially transfer the toner image formed on the photosensitive drum 103 onto the intermediate transfer belt 107. The image forming apparatus 1 also includes a secondary transfer roller 109 that transfers the toner image on the intermediate transfer belt 107 onto a recording material S conveyed from a paper feed unit 101, and a fixing device 100 that fixes the secondarily transferred image onto the recording material S. Note that, other than the intermediate transfer method using the intermediate transfer belt 107 described above, a direct transfer method in which an image is directly transferred from the photosensitive drum 103 to the recording material may also be used.

[0017] After the primary transfer, toner remains on the surfaces of the photosensitive drums 103Y, 103M, 103C, and 103K. The remaining toner is removed by drum cleaning devices (first cleaning devices) 8Y, 8M, 8C, and 8K (hereinafter, also collectively referred to as "drum cleaning devices 8") and collected in a collected toner container 5.

[0018] After the secondary transfer, toner remains on the surface of the intermediate transfer belt 107. This residual toner is removed by a belt cleaning device (second cleaning device) 7 and collected in a collected toner container 5.

[0019] (Image formation process) Next, the image forming process of the image forming apparatus will be briefly described. The charger 104Y charges the surface of the photosensitive drum 103Y. The exposure unit 500Y exposes the surface of the photosensitive drum 103Y charged by the charger 104Y. As a result, an electrostatic latent image is formed on the photosensitive drum 103Y. Next, the developer 106Y develops the electrostatic latent image formed on the photosensitive drum 103Y with yellow toner. The yellow toner image developed on the surface of the photosensitive drum 103Y is transferred onto the intermediate transfer belt 107 by the primary transfer roller 108Y. The magenta, cyan, and black toner images are also transferred onto the intermediate transfer belt 107 in a similar image forming process.

[0020] The toner images of each color transferred onto the intermediate transfer belt 107 are transported to a secondary transfer portion T2 by the intermediate transfer belt 107. A transfer bias is applied to a secondary transfer roller 109 disposed at the secondary transfer portion T2 to transfer the toner images onto a recording material S. The toner images transported to the secondary transfer portion T2 are transferred onto the recording material S transported from a paper feed portion (paper feed cassette) 101 by the transfer bias of the secondary transfer roller 109.

[0021] The recording material S is stored in a stacked form in the paper feed unit 101, and is fed to the conveying path 20 in accordance with the image formation timing. The paper feed method is as follows: first, the leading edge of the recording material S is flipped up by the friction of the paper feed roller 80, and only one sheet of the recording material S is conveyed to the conveying path 20 by a paper separating conveying roller pair 9 to prevent double feeding of the recording material S. Thereafter, the recording material S is pulled out by the conveying roller pair 10, and conveyed through the conveying path 20 to the registration roller pair 11, where it is stopped temporarily. Note that the registration roller pair 11 performs skew correction and timing correction, and then conveys the recording material to the secondary transfer unit T2.

[0022] The recording material S onto which the toner image has been transferred at the secondary transfer portion T2 is conveyed to the fixing device 100. The fixing device 100 fixes the toner image onto the recording material S by heat and pressure. The recording material S which has been subjected to the fixing process by the fixing device 100 is discharged to a paper discharge portion 111.

[0023] As shown in FIG. 1, the image forming apparatus 1 includes toner containers 4Y, 4M, 4C, and 4K (hereinafter, collectively referred to simply as "toner containers 4"). When an image is formed, the amount of toner in a developing unit 641 (described later) decreases. At that time, the toner is supplied to the developing unit 641 (described later) from the toner containers 4Y, 4M, 4C, and 4K provided corresponding to the image forming sections 102Y, 102M, 102C, and 102K through pipes (not shown). That is, in the developing unit 641 (described later) provided in the image forming apparatus 1 described in this embodiment, new toner is replenished from the toner container 4, while a part of the excess toner is transported to the collected toner container 5 as residual toner.

[0024] (Drum unit and developing unit) A drum unit 518, which is an example of a replaceable unit, is attached to the image forming apparatus 1 of this embodiment. The drum unit 518 is a cartridge that is replaced by an operator such as a user or a maintenance technician. The drum unit 518 (Y, M, C, K) of this embodiment includes photosensitive drums 103 (Y, M, C, K) rotatably supported on a frame of the drum unit 518.

[0025] In addition, the image forming apparatus 1 of this embodiment is provided with a developing unit 641 separate from the drum unit 518. The developing unit 641 of this embodiment is a cartridge in which the developing device 106 and the toner storage unit shown in FIG. 1 are integrated. The developing device 106 is provided with a developing sleeve, which is a developer carrier that carries the developer. The developing unit 641 is provided with a plurality of gears for rotating a screw for stirring the toner and carrier. When these gears deteriorate over time, an operator removes the developing unit 641 from the main body of the image forming apparatus 1 and replaces it. In addition, a certain amount of toner is removed from the developing unit 641 as residual toner and transported to the collected toner container 5. The embodiment of the drum unit 518 and the developing unit 641 may be a process cartridge in which the drum unit 518 and the developing unit 641 are integrated.

[0026] Here, as shown in FIG. 1, in the following description, one side in the direction in which the drum unit 518 is inserted into and removed from the image forming apparatus 1 is defined as the front side (near side or front side), and the other side is defined as the rear side (rear side or back side). In addition, when the photosensitive drum 103K on which the electrostatic latent image of the black toner image is formed is taken as a reference, the side on which the photosensitive drum 103Y on which the electrostatic latent image of the yellow toner image is formed is disposed is defined as the left side. When the photosensitive drum 103Y on which the electrostatic latent image of the yellow toner image is formed is taken as a reference, the side on which the photosensitive drum 103K on which the electrostatic latent image of the black toner image is formed is defined as the right side. Furthermore, the direction perpendicular to the front-rear direction and the left-right direction defined here and vertically upward is defined as the up direction, and the direction perpendicular to the front-rear direction and the left-right direction defined here and vertically downward is defined as the down direction. The defined front direction, rear direction, right direction, left direction, up direction, and down direction are shown in FIG. 2.

[0027] In the following description, the rotation axis direction of the photosensitive drum 103 is the same as the front-rear direction shown in FIG. 2. The longitudinal direction of the optical print head 105 is also the same as the front-rear direction shown in FIG. 2. That is, the rotation axis direction of the photosensitive drum 103 and the longitudinal direction of the optical print head 105 are the same as each other. Moreover, one end side in the rotation axis direction of the photosensitive drum 103 means the front side as defined here, and the other end side means the rear side as defined here. One end side and the other end side in the front-rear direction also correspond to the front side and the rear side as defined here. One end side in the left-right direction means the right side as defined here, and the other end side means the left side as defined here.

[0028] (Exposure unit) Next, an exposure unit 520 including the optical print head 105 will be described with reference to FIGS.

[0029] As shown in Figures 4 and 5, the exposure unit 520 includes an optical print head 105 that exposes the photosensitive drum 103, and a moving mechanism 640 that moves the optical print head 105 between an exposure position where the photosensitive drum 103 is exposed and a separated position that is further away from the photosensitive drum 103 than the exposure position.

[0030] (Optical print head) Next, the optical print head 105 provided in the exposure unit 500 will be described. Here, as an example of an exposure method adopted in an electrophotographic image forming apparatus, there is a laser beam scanning exposure method in which a semiconductor laser irradiation beam is scanned by a rotating polygon mirror or the like and a photosensitive drum is exposed via an f-θ lens or the like. The "optical print head 105" described in this embodiment is used for an LED exposure method in which the photosensitive drum 103 is exposed by using light emitting elements such as LEDs arranged along the rotation axis direction of the photosensitive drum 103, and is not used for the laser beam scanning exposure method mentioned above.

[0031] The optical print head 105 described in this embodiment is provided vertically below the rotation axis of the photosensitive drum 103, and an LED 503 included in the optical print head 105 exposes the photosensitive drum 103 from below. Fig. 2 is a schematic perspective view of the optical print head 105 provided in the image forming apparatus 1 of this embodiment.

[0032] The optical print head 105 has an elongated shape (longitudinal shape) extending in the direction of the rotation axis of the photosensitive drum 103. The optical print head 105 also includes a holding member 505 (an example of a holder), a lens array 506, and a substrate 502 (see FIG. 3). The holding member 505 also includes a front pin 507 and a rear pin 508 as abutment members, and a front spring holder 511 and a rear spring holder 512 that hold a front spring 509 and a rear spring 510. The holding member 505 holds the substrate 502 and the lens array 506.

[0033] Next, the substrate 502 will be described. Fig. 3(a) is a schematic perspective view of the substrate 502 in the optical print head 105. Fig. 3(b) is a diagram showing an arrangement of a plurality of LEDs 503 provided on the substrate 502, and Fig. 3(c) is an enlarged view of Fig. 3(b).

[0034] An LED chip 639 is mounted on the substrate 502. As shown in Fig. 3(a), the LED chip 639 is provided on one surface of the substrate 502, and a long FFC connector 504 is provided on the other surface (the surface opposite to the side on which the light emitting elements are arranged). The FFC connector 504 is attached to the lower surface of the substrate 502 so that its longitudinal direction is along the longitudinal direction of the substrate 502. The substrate 502 is provided with wiring for supplying signals to each LED chip 639. One end of a flexible flat cable (FFC, not shown), which is an example of a cable, is connected to the connector 504.

[0035] Although not shown, the image forming apparatus 1 is provided with a substrate having a control unit and a connector. The other end of the FFC is connected to the connector. That is, the FFC electrically connects the control unit and the substrate 502. A control signal (drive signal) is input to the substrate 502 from the control unit of the image forming apparatus 1 via the FFC and the connector 504. The LED chip 639 is driven by the control signal input to the substrate 502.

[0036] The LED chip 639 mounted on the substrate 502 will be described in more detail. As shown in FIG. 3(b) and FIG. 3(c), a plurality of LED chips 639-1 to 639-29 (29 chips) each having a plurality of LEDs 503 (an example of a light-emitting element) arranged thereon are arranged on one surface of the substrate 502. Each of the LED chips 639-1 to 639-29 has 516 LEDs 503 arranged in a row in its longitudinal direction. In the longitudinal direction of the LED chip 639, the center-to-center distance k2 between adjacent LEDs 503 corresponds to the resolution of the image forming apparatus 1. Since the resolution of the image forming apparatus 1 of this embodiment is 1200 dpi, the LEDs 503 are arranged in a row in the longitudinal direction of the LED chips 639-1 to 639-29 such that the center-to-center distance between adjacent LEDs 503 is 21.16 μm. Therefore, the exposure range of the optical print head 105 of this embodiment is about 314 mm. The photosensitive layer of the photosensitive drum 103 is formed with a width of 314 mm or more. Since the length of the long side of an A4 size recording paper and the length of the short side of an A3 size recording paper are 297 mm, the optical print head 105 of this embodiment has an exposure range capable of forming images on the A4 size recording paper and the A3 size recording paper.

[0037] The LED chips 639-1 to 639-29 are alternately arranged in two rows along the rotation axis direction of the photosensitive drum 103. That is, as shown in FIG. 3B, the odd-numbered LED chips 639-1, 639-3, . . . 639-29 counting from the left side are mounted in a row in the longitudinal direction of the substrate 502. Also, the even-numbered LED chips 639-2, 639-4, . . . 639-28 counting from the left side are mounted in a row in the longitudinal direction of the substrate 502. By arranging the LED chips 639 in this manner, as shown in FIG. 3C, in the longitudinal direction of the LED chips 639, the center-to-center distance k1 between the LEDs 503 arranged at one end of one LED chip 639 and the other end of the other LED chip 639 in different adjacent LED chips 639 can be made equal to the center-to-center distance k2 between the adjacent LEDs 503 on one LED chip 639.

[0038] In this embodiment, the light-emitting element is a semiconductor LED, which is a light-emitting diode, but it may be, for example, an OLED (Organic Light Emitting Diode). This OLED is also called an organic EL (Organic Electro-Luminescence), and is a current-driven light-emitting element. For example, the OLEDs are arranged in a line along the main scanning direction (the direction of the rotation axis of the photosensitive drum 103) on a TFT (Thin Film Transistor) substrate, and are electrically connected in parallel by power supply wiring also provided along the main scanning direction.

[0039] Next, the lens array 506 will be described. FIG. 3(d) is a schematic diagram of the lens array 506 when viewed from the photosensitive drum 103 side. FIG. 3(e) is a schematic perspective view of the lens array 506. As shown in FIG. 3(d), a plurality of lenses are arranged in two rows along the arrangement direction of the plurality of LEDs 503. The lenses are arranged alternately such that one lens in one row is arranged so as to be in contact with both of the lenses adjacent to each other in the arrangement direction of the lenses in the other row. Each lens is a cylindrical glass rod lens. The material of the lens is not limited to glass, and may be plastic. The shape of the lens is also not limited to cylindrical, and may be a polygonal column such as a hexagonal column.

[0040] The dotted line Z in FIG. 3(e) indicates the optical axis of the lens. The optical print head 105 can be moved in a direction (up and down) generally along the optical axis of the lens indicated by the dotted line Z by a moving mechanism 640 (see FIGS. 4 and 5) described later. The optical axis of the lens here means a line connecting the center of the light emission surface of the lens and the focal point of the lens. The radiation light emitted from the LED 503 is incident on the lens of the lens array 506. The lens has a function of focusing the incident radiation light on the surface of the photosensitive drum 103. The attachment position of the lens array 506 with respect to the opening 701 (see FIG. 2) is adjusted during assembly of the optical print head 105 so that the distance between the light emission surface of the LED 503 and the light incidence surface of the lens is approximately equal to the distance between the light emission surface of the lens and the surface of the photosensitive drum 103.

[0041] (Moving mechanism) Next, a description will be given of a moving mechanism 640 that moves the optical print head 105 to an exposure position relative to the photosensitive drum 103 and a separated position that is farther away from the photosensitive drum 103 than the exposure position. The optical print head 105 is disposed close to the photosensitive drum 103 and has a function of exposing the photosensitive drum 103. Therefore, if the optical print head 105 remains at the exposure position when the drum unit 518 is removed from the image forming apparatus 1 for maintenance of the image forming apparatus 1 or the like, the optical print head 105 may become an obstacle when removing the drum unit 518. Therefore, the optical print head 105 is in the exposure position close to the photosensitive drum 103 during exposure, but is required to have a moving function to move to a separated position farther away from the photosensitive drum than the exposure position during maintenance of the image forming apparatus 1.

[0042] FIG. 4 is a side view of the exposure unit 500 when the optical print head 105 is in the exposure position. FIG. 4 is a view from the right side. FIG. 5 is a side view of the exposure unit 500 when the optical print head 105 is in the separated position. Although the drum unit 518 is not shown, when the optical print head 105 is in the exposure position shown in FIG. 4, the front pin 516 and the rear pin 517 provided at both ends in the front-rear direction are in contact with predetermined positions of the drum unit 518 supporting the photosensitive drum 103. At that time, an upward biasing force is applied to the optical print head 105 by the front spring 509 and the rear spring 510 (see FIG. 2) held by the front spring holder 511 and the rear spring holder 512. The front pin 516, the rear pin 517, the front spring holder 511, and the rear spring holder 512 are provided on the holding member 505. Front spring 509 and rear spring 510 are urging members that urge optical print head 105 toward photosensitive drum 103, and are held by front spring holder 511 and rear spring holder 512. Optical print head 105 is urged toward photosensitive drum 103 by front spring 509 and rear spring 510, which are urging members, and front pin 516 and rear pin 517 each abut against drum unit 518. This keeps the distance between optical print head 105 and the surface of photosensitive drum 103 constant at the exposure position.

[0043] As shown in FIGS. 4 and 5, the movement mechanism 640 that moves the optical print head 105 between the exposure position and the separated position includes a frame 526 as a support member, a slide member 525, a first link mechanism 530, and a second link mechanism 540.

[0044] The frame 526 is formed by bending a metal plate into a U-shape by press working. The frame 526 is a longitudinal member extending in the direction of the rotation axis of the photosensitive drum 103. One end side (front side) of the frame 526 in the longitudinal direction is fixed to a front plate (not shown) of the image forming apparatus 1, and the other end side (rear side) of the frame 526 in the longitudinal direction is fixed to a rear plate (not shown) of the image forming apparatus 1. In this way, the position of the frame 526 with respect to the photosensitive drum 103 is fixed on the side opposite to the side on which the photosensitive drum 103 is disposed with respect to the holding member 505.

[0045] The frame 526 includes a slide member (moving member) 525 that is movable in the longitudinal direction of the frame 526. As the slide member 525 moves back and forth relative to the frame 526, the link mechanisms 530, 540 rotate and the optical print head 105 moves up and down.

[0046] The first link mechanism 530 includes a link member 535 that connects the front spring holder 511 and the slide member 525, and a link member 536 that connects the link member 535 and the frame 526. The second link mechanism 540 includes a link member 545 that connects the rear spring holder 512 and the slide member 525, and a link member 546 that connects the link member 545 and the frame 526. The first link mechanism 530 is attached forward of the center of the holding member 505 in the direction of the rotation axis of the photosensitive drum 103, and the second link mechanism 540 is attached rearward of the center of the holding member 505 in the direction of the rotation axis of the photosensitive drum 103.

[0047] As a cover (not shown) provided on the front side of image forming apparatus 1 is opened or closed, slide member 525 slides forward and backward relative to frame 526. Link members 535, 536, 545, and 546 rotate in conjunction with the sliding movement of slide member 525, and optical print head 105 moves up and down.

[0048] In this embodiment, as shown in Fig. 4, when the slide member 525 is moved forward in the front-rear direction relative to the frame 526, the link members 535, 536, 545, and 546 rotate in conjunction with the movement, and the optical print head 105 rises to the exposure position. On the other hand, as shown in Fig. 5, when the slide member 525 is moved backward in the front-rear direction relative to the frame 526, the link members 535, 536, 545, and 546 rotate in conjunction with the movement, and the optical print head 105 descends to the separated position.

[0049] (Prevention of foreign matter entering optical print heads) Next, a description will be given of measures against the intrusion of foreign matter into the optical print head 105 of this embodiment.

[0050] 6 is a perspective view showing the substrate 502 on which the LED 503 is mounted. This figure is a perspective view from the direction in which the FFC connector 504 is mounted, and the LED 503 is mounted on the other side. A driver IC 900 for emitting and controlling the LED 503 is mounted on both ends of the FFC connector 504. In order to simplify the explanation, other mounted components such as resistors and capacitors are not shown. The driver IC 900 used in this embodiment is an IC chip that is 8 mm square and 0.85 mm thick, and multiple electrode pads on the back surface of the IC chip are electrically connected to the electrodes on the substrate 502 by solder.

[0051] Fig. 7 is a perspective view showing a state in which the substrate 502, the lens array 506 (not shown in Fig. 7), the front spring holder 511, and the rear spring holder 512 are held by the holding member 505. Fig. 8 is a perspective cross-sectional view taken along the driver IC 900 (the position indicated by the arrow AA in the figure) in Fig. 7. Fig. 9 is a perspective cross-sectional view taken along the front spring holder 511 (the position indicated by the arrow BB in the figure) in Fig. 7. Fig. 10 is a perspective cross-sectional view taken along the rear spring holder 512 (the position indicated by the arrow CC in the figure) in Fig. 7.

[0052] Here, the holding member 505 in this embodiment is a metal thin plate with a thickness of about 1 mm, and is a part processed by pressing an electro-galvanized steel sheet. As described above, the holding member 505 has the front pin 507 and the rear pin 508 disposed as abutment members at both ends in the longitudinal direction, and is formed into a U-shape by pressing, rather than being made into a box shape with all four sides bent. The shape of the holding member 505 will be described below.

[0053] The holding member 505 has a base portion 802 in which an opening 701 into which the lens array 506 is inserted is formed. The holding member 505 also has a first extension portion 804R extending from one side in the short side direction perpendicular to the longitudinal direction of the base portion 802 in a direction away from the photosensitive drum 103. The holding member 505 also has a second extension portion 804L extending from the other side in the short side direction of the base portion 802 in a direction away from the photosensitive drum 103. The extension portion 804R and the extension portion 804L form a substrate holding portion for holding the substrate 502 inserted in the holding member 505 between the extension portion 804R and the extension portion 804L. The base portion 802, the first extension portion 804R, and the second extension portion 804L are integral, forming the holding member 505 that holds the lens array 506 and the substrate 502, and are formed in a substantially U-shape.

[0054] As described above, the holding member 505 includes the front pin 516 and the rear pin 517 as contact members, and the front spring holder 511 and the rear spring holder 512 as mounting members. In the rotation axis direction of the photosensitive drum 103 (longitudinal direction of the substrate), the photosensitive layer of the photosensitive drum 103 is formed with a width equal to or larger than the exposure range of the optical print head 105. Although not shown, the front pin 516 and the rear pin 517 are in contact with the drum unit 518 on the outer side of the photosensitive drum 103. Therefore, the front spring holder 511 and the rear spring holder 512 are disposed between both ends of the substrate 502 in the longitudinal direction and the front pin 507 and the rear pin 508. As described above, the front spring holder 511 and the rear spring holder 512 are connected to the link members 535 and 454, respectively, and are adhesively fixed to the holding member 505 at predetermined positions. By making front spring holder 511 and rear spring holder 512 separate from holding member 505, the manufacturing cost of holding member 505 can be kept relatively low.

[0055] The front spring holder 511 and the rear spring holder 512 are provided on the holding member 505. The front spring holder 511 and the rear spring holder 512 are provided outside the end of the substrate 502 in the longitudinal direction of the substrate 502. The front spring holder 511 and the rear spring holder 512 include a front mounting portion 511a and a rear mounting portion 512a to which a moving mechanism 640 that moves the holding member 505 between an exposure position and a separated position (retracted position) is attached. Specifically, the front spring holder 511 includes a front mounting portion 511a to which a link member 535 of the first link mechanism 530 is attached. The rear spring holder 512 includes a rear mounting portion 512a to which a link member 545 of the second link mechanism 540 is attached.

[0056] As described above, the front spring holder 511 and the rear spring holder 512 hold the front spring 509 and the rear spring 510 which are biasing members that bias the optical print head 105 in the direction of the photosensitive drum 103 .

[0057] The spring holder front 511 has a wall portion front 902 between the end of the substrate 502 and the mounting portion front 511a in the longitudinal direction. The spring holder rear 512 has a wall portion rear 903 between the end of the substrate 502 and the mounting portion rear 512a in the longitudinal direction. That is, in this embodiment, the spring holder front 511 is a mounting member in which the mounting portion front 511a and the wall portion front 902 are integrally molded with resin, and is held by the holding member 505 on the outside of the end of the substrate 502 in the longitudinal direction. The spring holder rear 512 is a mounting member in which the mounting portion rear 512a and the wall portion rear 903 are integrally molded with resin, and is held by the holding member 505 on the outside of the end of the substrate 502 in the longitudinal direction.

[0058] In this embodiment, the front mounting portion 511a and the front wall portion 902 are integrally molded as the front spring holder 511, and the rear mounting portion 512a and the rear wall portion 903 are integrally molded as the rear spring holder 512, but the present invention is not limited to this. The front wall portion 902, the rear wall portion 903, the front mounting portion 511a, and the rear mounting portion 512a may be provided separately.

[0059] The substrate 502 is rectangular, with a length in the longitudinal direction of 340 mm and a length in the lateral direction perpendicular to the longitudinal direction of 8.5 mm. If the longitudinal length of the substrate 502 is manufactured with the same precision as the lateral length, for example, with a tolerance of ±0.5 mm, the cost will be high. Therefore, in order to keep the manufacturing cost relatively low, the longitudinal length of the substrate 502 is allowed to have a variation of about ±1 mm. Therefore, the substrate 502 held by the holding member 505 and the front spring holder 511 and rear spring holder 512 bonded and fixed to the holding member 505 must be disposed with a gap in the direction of the rotation axis (longitudinal direction). The gap is wider than the gap between the wall surfaces (extensions 804R, 804L) of the U-shaped lateral direction of the holding member 505 and the substrate 502, which is about 2 mm, due to differences in tolerance. Here, if the manufacturing tolerance of substrate 502 can be reduced, the distance between front spring holder 511, rear spring holder 512, and the longitudinal end of substrate 502 can be made smaller than 2 mm. In this embodiment, the distance between front wall 902 of front spring holder 511 and the longitudinal end of the substrate, and the distance between rear wall 903 of rear spring holder 512 and the longitudinal end of substrate 502 are 2 mm or less.

[0060] Next, the configuration of the optical print head 105 will be described in more detail. The opening 701 as a lens attachment portion formed in the base portion 802 of the holding member 505 is an opening one size larger than the lens array 506. The lens array 506 is inserted into the opening 701 of the holding member 505, its position is adjusted, and it is fixed to the holding member 505 by adhesive. The substrate 502 is formed one size smaller than the interval between the extension portion 804R and the extension portion 804L of the holding member 505, and the position of the substrate 502 is adjusted so that the optical axis of the LED 503 is aligned with the center of the lens array 506. Thereafter, the substrate 502 is fixed to the holding member 505 by adhesive between the extension portions 804R and 804L on both sides of the short side direction of the holding member 505. This adhesive is, for example, an ultraviolet-curing adhesive, and is applied to the bonding portion in a liquid or gel state and then cured by irradiation of ultraviolet light.

[0061] Here, lens array 506 and substrate 502 are fixed to holding member 505 in a comparatively short time by multiple-point adhesion, and even after bonding with an adhesive, gaps remain between lens array 506 and holding member 505 and between substrate 502 and holding member 505. In addition, the distance between the longitudinal end of substrate 502 and front spring holder 511 and rear spring holder 512 is the above-mentioned 2 mm or less. Therefore, foreign matter such as toner can enter the space around holding member 505 and LED 503 and lens array 506 of substrate 502, which may cause problems such as a decrease in the amount of light.

[0062] 8, in this embodiment, sealant 513 is applied so as to come into contact with both lens array 506 and holding member 505, thereby sealing the gap between lens array 506 inserted into and bonded to opening 701 of holding member 505 and holding member 505. Also, sealant 514 is applied so as to come into contact with both substrate 502 and extensions 804R, 804L, thereby sealing the gap between substrate 502 inserted between and bonded to extensions 804R and 804L of holding member 505 and each of extensions 804R, 804L.

[0063] Further, as shown in Figs. 9 and 10, the sealant 514 is applied so as to come into contact with both the substrate 502 and the front spring holder 511 and rear spring holder 512. Here, a front wall 902 is provided on the side of the front spring holder 511 facing the substrate 502, and a rear wall 903 is provided on the side of the rear spring holder 512 facing the substrate 502. The front wall 902 is provided between the end of the substrate 502 and the front mounting part 511a of the front spring holder 511 in the direction of the rotation axis of the photosensitive drum 103. The rear wall 903 is provided between the end of the substrate 502 and the rear mounting part 512a of the rear spring holder 512 in the direction of the rotation axis of the photosensitive drum 103. The front wall 902 and the rear wall 903 are spaced from the end of the substrate 502 by the aforementioned 2 mm or less in the direction of the rotation axis. The sealant 514 is applied so as to be in contact with both the front wall 902 and the substrate 502, and also with both the rear wall 903 and the substrate 502. Thus, the sealant 514 seals the gap between the edge of the substrate 502 and the front wall 902, and the gap between the edge of the substrate 502 and the rear wall 903.

[0064] Further, the front wall 902 and the rear wall 903 have shapes that fit the inner surface of the U-shape formed by the base portion 802 of the holding member 505, the first extending portion 804R, and the second extending portion 804L.

[0065] Furthermore, the front wall 902 and the rear wall 903 are provided to protrude in a direction away from the photosensitive drum 103 from the substrate 502 held by the holding member 505 in the movement direction (up and down direction) of the holding member 505. That is, in a bottom exposure type optical print head, the front wall 902 and the rear wall 903 extend upward from the position of the substrate 502. Therefore, when the sealant 514 is applied so as to come into contact with both the substrate 502 and the front wall 902 and the rear wall 903, the sealant 514 does not go over the front wall 902 and the rear wall 903.

[0066] The sealants 513 and 514 solidify over time and seal the gap between the lens array 506 and the holding member 505, the gap between the substrate 502 and the holding member 505, and the gap between the substrate 502 and the (wall) of the spring holder. This allows the optical print head 105 to almost completely seal the space around the LEDs 503 and the lens array 506 on the substrate 502, reducing the intrusion of foreign matter. In particular, the end of the substrate 502 in the direction of the rotation axis is sealed by the wall and the sealant, further reducing the intrusion of foreign matter. In addition, since the wall is provided and the gap between the wall and the sealant 514 is sealed by the sealant 514, the inflow of the sealant 514 into the LEDs 503 mounted on the substrate 502 can be suppressed. In addition, the inflow of the sealant 514 into the lens array 506 held by the holding member 505 can be suppressed. In addition, the amount of sealant 514 used can be reduced, leading to cost reduction.

[0067] In this embodiment, a silicone having a suitable degree of flexibility is used as the sealing material, for example, SE9189L, a one-component room temperature curing RTV rubber from Dow Toray Industries, Inc. Due to the nature of silicone, it is relatively soft, and when filled, it flexibly deforms and can almost completely seal gaps. In addition, while it is flexible, it has the rigidity and strength of a gel, and the viscosity of SE9189L is 22 Pa s, so it does not flow off like a liquid and can maintain the shape it was applied to.

[0068] As a method of applying the sealant, a dispenser is preferably used to precisely apply the liquid agent. As a nozzle needle for discharging the sealant, SNA-12G by Musashi Engineering Co., Ltd. is used. The inner diameter of the discharge port is larger than the distance between the substrate 502 and the front spring holder 511 and the rear spring holder 512. Specifically, the inner diameter of the discharge port (SNA-12G) is 2.27 mm, and it is possible to apply the sealant at once to the distance of about 2 mm between the substrate 502 and the front spring holder 511 and the rear spring holder 512.

[0069] Example 2 An optical print head according to Example 2 will be described with reference to Figures 11 and 12. Figure 11 is a cross-sectional perspective view of the optical print head according to this example taken at the front of the spring holder 511 (at the location of the arrow BB in Figure 7) in the same manner as Figure 9. Also, Figure 12 is a cross-sectional perspective view of the optical print head according to this example taken at the rear of the spring holder 512 (at the location of the arrow CC in Figure 7) in the same manner as Figure 10.

[0070] The optical print head according to this embodiment is different in that the wall portion has a receiving portion, and the receiving portion is provided with a first groove portion. The other configurations are the same as those of the above-mentioned embodiment, so the description will be omitted here.

[0071] The front wall 902 has a front receiving portion 904 extending from the front wall 902 toward the lens side along the inner surface of the base portion 802 of the holding member 505 that faces the mounting surface on which the LEDs are mounted of the substrate 502. The front receiving portion 904 is located between the front wall 902 and the lens array 506 in the longitudinal direction of the substrate 502.

[0072] The rear wall 903 has a rear receiving portion 905 extending from the rear wall 903 toward the lens side along the inner surface of the base portion 802 of the holding member 505 that faces the mounting surface on which the LEDs of the substrate 502 are mounted. The rear receiving portion 905 is located between the rear wall 903 and the lens array 506 in the longitudinal direction of the substrate 502.

[0073] The front receiving portion 904 has a first groove front 906 formed on an opposing surface 904a facing the mounting surface of the substrate 502, along a direction perpendicular to the longitudinal direction. The first groove front 906 forms a step between the opposing surface 904a and the front wall 902. The rear receiving portion 905 has a first groove rear 907 formed on an opposing surface 905a facing the mounting surface of the substrate 502, along a direction perpendicular to the longitudinal direction. The first groove rear 907 forms a step between the opposing surface 905a and the rear wall 903.

[0074] According to the above configuration, even if the sealant 514 applied so as to come into contact with both the substrate 502 and the front wall 902 flows out downward from the gap between the substrate 502 and the front wall 902, it can be received by the front receiving portion 904 and furthermore can be kept in the front first groove portion 906. This makes it possible to suppress the sealant 514 from flowing into the LEDs 503 mounted on the substrate 502. It is also possible to suppress the sealant 514 from flowing into the lens array 506 held by the holding member 505. Even if the sealant 514 applied so as to come into contact with both the substrate 502 and the rear wall 903 flows out downward from the gap between the substrate 502 and the rear wall 903, it can be suppressed in the same way.

[0075] Furthermore, the front receiving portion 904 and the rear receiving portion 905 are provided outside the end of the lens array 506 held by the holding member 505 in the direction of the rotation axis, and outside the area where the LEDs are mounted on the substrate 502. Therefore, the front receiving portion 904 and the rear receiving portion 905 do not block the light emitted from the LEDs toward the lens array 506.

[0076] Example 3 An optical print head according to Example 3 will be described with reference to Fig. 13 and Fig. 14. Fig. 13 is a perspective view of the optical print head according to this example, before application of a sealant near the front 511 of the spring holder. Also, Fig. 13 is a perspective view of the optical print head according to this example, before application of a sealant near the rear 512 of the spring holder.

[0077] The optical print head according to this embodiment differs in that a notch is further provided in the receiving portion of the wall of the spring holder. The rest of the configuration is the same as in the above-mentioned embodiment, so a description thereof will be omitted here.

[0078] The receiving portion front 904 of the spring holder front 511 has a notch portion front 908 formed in a direction perpendicular to the longitudinal direction on a first surface (not shown) facing the first extending portion 804R of the holding member 505. The notch portion front 908 forms a step between the first surface and the wall portion front 902. The receiving portion front 904 has a notch portion front 908 formed in a direction perpendicular to the longitudinal direction on a second surface (not shown) facing the second extending portion 804L of the holding member 505. The notch portion front 908 forms a step between the second surface and the wall portion front 902. The notch portion front 908 facing the first extending portion 804R and the notch portion front 908 facing the second extending portion 804L are connected to the first groove portion front 906.

[0079] The receiving portion rear 905 of the spring holder rear 512 has a notch rear 909 on a first surface (not shown) facing the first extending portion 804R of the holding member 505 along a direction perpendicular to the longitudinal direction. The notch rear 909 forms a step between the first surface and the wall portion rear 903. The receiving portion rear 905 has a notch rear 909 on a second surface (not shown) facing the second extending portion 804L of the holding member 505 along a direction perpendicular to the longitudinal direction. The notch rear 909 forms a step between the second surface and the wall portion rear 903. The notch rear 909 facing the first extending portion 804R and the notch rear 909 facing the second extending portion 804L are connected to the first groove portion rear 907.

[0080] According to the above configuration, the front cutout 908 and the rear cutout 909 are provided near the corners of the substrate 502 that face the wall of each spring holder. Therefore, the sealant 514 can be easily filled into the corners of the substrate 502 along each wall. Even if the sealant 514 flows downward from the gap between the substrate end and the wall, it is possible to more effectively prevent the sealant 514 from flowing down to the lens array 506.

[0081] In addition, the configuration in which the front cutout portion 908 and the rear cutout portion 909 are connected to the front first groove portion 906 and the rear first groove portion 907 described in the above-mentioned Example 2 has been exemplified, but the above-mentioned effect can be obtained even if the receiving portion is configured not to have the first groove portion.

[0082] Example 4 An optical print head according to Example 4 will be described with reference to Figures 15, 16, and 17. Figure 15 is a perspective view of the optical print head. Figure 16 is a cross-sectional perspective view of the optical print head when cut at the front of the spring holder 511 (at the location of the arrow D- in Figure 15). Figure 17 is a cross-sectional perspective view of the optical print head when cut at the rear of the spring holder 512 (at the location of the arrow E- in Figure 15).

[0083] The optical print head according to this embodiment differs in that a second groove is further provided in the receiving portion of the wall of the spring holder.A further difference is that a through hole connected to the second groove is provided in the base of the holding member.Other configurations are the same as those of the previously described embodiment, so a description thereof will be omitted here.

[0084] In optical print head 105, front spring holder 511 and rear spring holder 512 are adhesively fixed to holding member 505. However, it is conceivable that a small gap may be formed between front spring holder 511 and rear spring holder 512 and holding member 505. Therefore, optical print head 105 according to this embodiment is configured as follows to make it easier to fill with sealant 514 the sides of front spring holder 511 and rear spring holder 512 that face base portion 802 of holding member 505.

[0085] The receiving portion front 904 of the spring holder front 511 has a second groove front 911 provided along a direction perpendicular to the longitudinal direction on an opposing surface 904b that faces the base portion 802 of the holding member 505. The second groove front 911 forms a step between the opposing surface 904b and the wall front 902. The second groove front 911 is connected to a notch front 908 that faces the first extending portion 804R and a notch front 908 that faces the second extending portion 804L shown in FIG.

[0086] The receiving portion rear 905 of the spring holder rear 512 has a second groove rear 912 provided along a direction perpendicular to the longitudinal direction on an opposing surface 905b that faces the base portion 802 of the holding member 505. The second groove rear 912 forms a step between the opposing surface 905b and the wall portion rear 903. The second groove rear 912 is connected to a notch rear 909 that faces the first extending portion 804R and a notch rear 909 that faces the second extending portion 804L, as shown in FIG.

[0087] Further, a front through hole 913 connected to the second front groove 911 is provided in the base portion 802 of the holding member 505. Similarly, a rear through hole 914 connected to the second rear groove 912 is provided in the base portion 802 of the holding member 505.

[0088] According to the above configuration, sealant 514 is filled from through-hole front 913 and through-hole rear 914 of base portion 802 of holding member 505 to second groove front 911 and second groove rear 912 of spring holder front 511 and spring holder rear 512. Therefore, spring holder front 511 and spring holder rear 512 can be sealed even if there is a small gap between holding member 505 and front 913 and rear 914 of spring holder front 511 and rear 512 of spring holder rear 512.

[0089] Here, the second groove front 911 and the second groove rear 912 are connected to the notch front 908 and the notch rear 909, respectively. Therefore, it is also possible to fill the second groove front 911 and the second groove rear 912 through the notch front 908 and the notch rear 909 without drilling a through hole in the base portion 802 of the holding member 505. [Explanation of symbols]

[0090] S...Recording material 1. Image forming device 103 ... Photosensitive drum 105 ...Optical print head 500 ... exposure unit 502 ... Substrate 504...FFC connector 505 ... Retaining member 506 ... Lens array 507,508 … Pins 509,510 …Spring 511,512 …Spring holder 511a, 512a … Mounting part 513,514 ...Sealing material 503...LED 525 ... Slide member 526 ... Frame 530,540 …Link mechanism 535,536,545,546 … Link member 639 ... LED chip 640...Movement mechanism 701...Aperture 802 ... Base section 804L,804R…extension part 902,903…Wall part 904,905 …Receiving part 904a, 904b, 905a, 905b...Opposing surface 906, 907 ... First groove 908,909 …Notch 911, 912 ... Second groove 913,914 ...Through holes

Claims

1. A substrate on which a plurality of light emitting elements are mounted; a lens that focuses the light emitted from the light-emitting element onto a photoconductor; a holding member configured to hold the substrate and the lens, the holding member being U-shaped and including a base portion having an opening into which the lens is inserted, a first extension portion extending from one side in a lateral direction perpendicular to the longitudinal direction of the substrate in a direction away from the photosensitive body, and a second extension portion extending from the other side in the lateral direction in a direction away from the photosensitive body, the lens inserted into the opening being held by the base portion, and the substrate being held by the first extension portion and the second extension portion; a wall portion disposed outside an end portion of the substrate in the longitudinal direction at a distance from the end portion and facing a surface of the substrate intersecting the longitudinal direction, the wall portion having a shape that follows an inner surface of a U-shape formed by the base portion, the first extension portion, and the second extension portion; a sealant that seals between the substrate and the wall portion in the longitudinal direction; 1. An optical print head comprising:

2. A distance between the end of the substrate and the wall portion in the longitudinal direction is 2 mm or less.

2. The optical print head according to claim 1.

3. the wall portion has a receiving portion extending from the wall portion toward the lens side along an inner surface of the base portion of the holding member that faces a mounting surface on which the light emitting element of the board is mounted, The receiving portion is located between the wall portion and the plurality of lenses in the longitudinal direction.

2. The optical print head according to claim 1.

4. The receiving portion has a first groove portion formed in a surface facing the mounting surface of the board along a direction perpendicular to the longitudinal direction.

4. The optical print head according to claim 3.

5. The receiving portion has a first surface facing the first extending portion of the holding member and a second surface facing the second extending portion of the holding member, the first surface having a notch formed along a direction perpendicular to the longitudinal direction.

4. The optical print head according to claim 3.

6. The receiving portion has a second groove provided on a surface facing the base portion of the holding member along a direction perpendicular to the longitudinal direction.

4. The optical print head according to claim 3.

7. A through hole communicating with the second groove portion is provided in the base portion of the holding member.

7. The optical print head according to claim 6.

8. The holding member is made of metal.

2. The optical print head according to claim 1.

9. An image forming apparatus having a photoconductor and an optical print head for exposing the photoconductor, 9. An image forming apparatus comprising the optical print head according to claim 1 as said optical print head.

Images