JP6525699B2 - Light scanning device, image forming apparatus provided with the light scanning device, and seal member used for the light scanning device - Google Patents

Description

  The present invention relates to a dustproof mechanism of an optical scanning device.

  An optical scanning device used in an electrophotographic image forming apparatus is known to include a light source (for example, a semiconductor laser) and a rotary polygon mirror. The light scanning device deflects a light beam (laser light) emitted by a light source by a rotating polygon mirror, and guides the deflected light beam onto a photosensitive member by an optical component such as a lens or a mirror. The image forming apparatus develops a latent image formed on the photosensitive member by scanning the photosensitive member with the light beam using toner, and transfers and fixes the developed toner image onto a recording medium. An image is formed on a recording medium.

  The light scanning device has a light receiving element that receives the light beam deflected by the rotating polygon mirror and generates a horizontal synchronization signal. By emitting the light beam based on the image data based on the horizontal synchronization signal in each scanning cycle of the light beam, the end of the image in the scanning direction of the light beam can be aligned.

  Patent Document 1 discloses an attachment mechanism of a light receiving element to an optical scanning device. As described in Patent Document 1, the light receiving element (photoelectric element) is mounted on a circuit board (drive board). The circuit board is fixed to the frame of the optical scanning device by screws. The frame of the light scanning device is formed with a through hole for passing the light beam deflected by the rotating polygon mirror. The circuit board is fixed to the frame so that the light receiving element on the circuit board is in contact with the exit of the through hole and can receive the light beam.

  In the case of an optical scanning device having a configuration in which there is a minute gap between the light receiving element and the frame, and dust or a mist-like chemical substance in the air can infiltrate into the optical scanning device from the gap, It is possible that dirt and dust invading the rotary polygon mirror and the optical components inside the light scanning device. To solve such a problem, for example, a sealing member such as elastically deformable rubber for filling the gap between the light receiving element and the frame is attached to the optical scanning device to prevent the entry of dust into the inside of the optical scanning device. A dustproof mechanism can be considered.

JP 2002-182138 A

  However, if the circuit board is fixed to the frame by screws after sandwiching a seal member such as an O-ring between the light receiving element described in Patent Document 1 and the frame, the following problems occur. That is, when the circuit board is assembled to the frame, the seal member sandwiched between the frame and the circuit board may become too hard, and the hardened seal member may stress the circuit board.

The present invention has been made in view of the above problems, and an optical scanning device according to the present invention comprises: a rotary polygon mirror that deflects a light beam emitted from the light source so that the light beam scans the photosensitive body.
A sensor including a light receiving element that receives a light beam deflected by the rotary polygon mirror to generate a synchronization signal that is a reference of an emission timing of the light beam from the light source based on the image data; A circuit board on which a wiring to which an input / output terminal of the sensor is connected is printed, and an optical box in which the rotating polygon mirror is mounted, the inside of the optical box A through hole through which the light beam deflected by the rotary polygon mirror is incident, and a protrusion surrounding the through hole and protruding outside the optical box, the light receiving element being the through hole A frame to which the circuit board is attached from the outside of the optical box so as to receive a light beam incident on a hole, and a fixing screw for fixing the circuit board to the frame An elastically deformable seal member made of rubber, which is interposed between the frame and the circuit board, and is in contact with the frame and the circuit board to fill the gap between the frame and the circuit board A sealing member, the sealing member having a first surface facing the frame, and a second surface located on the back surface of the first surface and facing the circuit board, A through hole communicating the first surface to the second surface is formed, and is formed integrally with the flexible member that is pressed and bent by the tip of the protrusion and the flexible member together with the flexible member, The circuit board is the optical box so that the light receiving element is disposed at the position surrounded by the through hole , The tip of the standing portion is in contact with the circuit board, and the flexible portion is A gap is formed between the second surface of the flexible portion and the circuit board in a non-bent state before being pressed by the protruding portion, and the flexible portion is pressed by the tip of the projecting portion By bending so as to enter the gap, a biasing force is applied to the standing portion integrally formed on the seal member together with the flexible portion toward the circuit board. I assume.

  According to the present invention, it is possible to reduce the stress on the circuit board caused by sandwiching the seal member by the circuit board on which the light receiving element is mounted and the optical box.

A schematic cross-sectional view of an image forming apparatus 100 according to the present embodiment A perspective view of an optical scanning device according to the present embodiment Top view and cross-sectional view of the optical scanning device according to the present embodiment An enlarged view of the optical scanning device according to the present embodiment Control block diagram of the image forming apparatus according to the present embodiment Timing chart of one scanning cycle of the image forming apparatus according to the present embodiment A perspective view of a light source unit according to the present embodiment Perspective view showing the laser holder attached to the optical box Enlarged view of the main part of the circuit board Perspective view and cross section of seal member Diagram showing the relationship between the optical box, circuit board, and seal member Modification of laser holder Modification of seal member

Example 1
(Image forming device)
FIG. 1 is a schematic cross-sectional view of the image forming apparatus 100 of the first embodiment. The image forming apparatus of FIG. 1 includes four image forming engines 101Y, 101M, 101C, and 101Bk that form toner images of yellow (Y), magenta (M), cyan (C), and black (Bk), respectively. ing. The symbols Y, M, C, and Bk are omitted except when describing specific colors below. The image forming engine 101 includes a photosensitive drum 102 which is a photosensitive member to be exposed by a light beam described later, a charging roller 103 which is a charging device, and a developing device 104. The charging roller 103 charges the photosensitive drum 102 to a uniform potential, and the developing device 104 toners the electrostatic latent image formed on the photosensitive drum 102 by the laser beam emitted from the optical scanning device 200. Develop with.

  The image forming apparatus 100 includes an intermediate transfer belt 105 to which a toner image on the photosensitive drum 102 is transferred. Then, the toner image of each color transferred to the intermediate transfer belt 105 is transferred by the transfer roller 107 onto the recording paper (recording medium) conveyed from the paper feeding unit 106. The recording sheet to which the toner image of each color is transferred is conveyed to the fixing unit 108. The toner image on the recording sheet is fixed on the recording sheet by passing between the fixing roller pair 109.

  The four image forming engines 101Y, 101M, 101C, and 101Bk are arranged in parallel below the intermediate transfer belt 105. The light scanning device 200a and the light scanning device 200b are disposed below the four imaging engines 101Y, 101M, 101C, and 101Bk. The optical scanning device 100 a is supported by a support 110 provided in the image forming apparatus 100. The optical scanning device 100 b is supported by a support portion 111 provided in the image forming apparatus 100.

(Optical scanning device)
FIG. 2 is a perspective view of the optical scanning devices 200 a and 200 b attached to the image forming apparatus 100. FIG. 3A is a top view of the light scanning devices 200a and 200b, and FIG. 3B is a cross-sectional view of the light scanning devices 200a and 200b.

  The optical scanning device 200 of this embodiment is provided with scanning paths of two laser beams in one housing. Therefore, in order to form an image of four colors of Y, M, C, and K, two light scanning devices (200a, 200b) on the YM side and the CK side are mounted on the image forming apparatus. Here, an embodiment will be described by taking the optical scanning device 200a on the YM side as an example.

  As shown in FIGS. 2 and 3A, the optical scanning device 200 a includes an optical box 201. The optical box 201 is a box-like frame. As shown in FIG. 2, optical components to be described later are attached to the inside of the optical box 201. In the present embodiment, the optical box 201 and a laser holder to be described later are collectively referred to as a frame.

  As shown in FIG. 3A, light source units 202Y and 202M described later are attached to the outer wall of the optical box 201. Further, inside the optical box 201, a polygon mirror 209 is attached. The laser beam LY emitted from the light source unit 202Y is incident on the reflecting surface of the polygon mirror 209 along the path of the dotted line Ly shown in FIG. 3A. The laser beam Lm emitted from the light source unit 202M is incident on the reflection surface of the polygon mirror 209 along the path of the dotted line Lm shown in FIG. 3A. The light source unit 202Y and the light source 202M are attached to the optical box 201 so that the reflection surface on which the laser light Ly is incident is different from the reflection surface on which the laser light Lm is incident.

  FIG. 3B is a cross-sectional view of the light scanning device 200A. The laser light Ly deflected by the polygon mirror 209 passes through the lens 210 and is reflected upward in the vertical direction by the reflection mirror 211. The laser beam Ly reflected by the reflection mirror 211 passes through the lens 212, passes above the polygon mirror 209, and is reflected by the reflection mirror 213. The laser beam Ly reflected by the reflection mirror 213 passes through a transparent window 212 provided on a lid 215 for closing the optical box 201. The laser beam Ly having passed through the transparent window 212 scans on the photosensitive drum 310Y.

  On the other hand, the laser beam Lm deflected by the polygon mirror 209 passes through the lens 216 and is reflected by the reflection mirror 217 upward in the vertical direction. The laser beam Lm reflected by the reflection mirror 217 passes through the lens 218, passes above the polygon mirror 209, and is reflected by the reflection mirror 219. The laser beam Lm reflected by the reflection mirror 219 passes through the transparent window 220 provided in the lid 215. The laser beam Lm that has passed through the transparent window 220 scans the photosensitive drum 310M.

  FIG. 4 is an enlarged view of the main part of FIG. FIG. 4 is a top view of the light scanning device 200a excluding the lens 212 and the lens 218, the reflection mirror 212 and the reflection mirror 213 shown in FIG. 3A. As shown in FIG. 4, on the circuit board of the light source unit 202Y, a light receiving element 222 (for example, an optical sensor such as a photodiode) which is a Beam Detector (BD) is mounted. Further, inside the optical box 201, a BD mirror 220 for reflecting the laser light emitted from the light source unit 202M and deflected by the polygon mirror 209 is attached. Further, inside the optical box 201, a BD lens 221 for condensing the laser light reflected by the BD mirror 220 on the light receiving element 222 is attached.

The BD mirror 220 is disposed on the scanning path of the laser light Lm. The BD mirror 220 is disposed at a position out of the image area on the photosensitive drum 102M. The light source unit 202M emits a laser beam so that the laser beam Lm scans on the BD mirror 220. The laser beam L _BD reflected by the BD mirror 220 passes through the BD lens 221. Then, the laser beam _{L BD} passing through the BD lens 221 is incident on the light receiving element 222 and enters the through holes provided in the side wall of the optical box 201.

The light receiving element 222 generates a BD signal (horizontal synchronization signal) which is a pulse signal by receiving the laser light _LBD .

  FIG. 5 is a control block diagram of the image forming apparatus 100 of the present embodiment. The image forming apparatus 100 of this embodiment includes a controller 500 in the image forming apparatus main body. The controller 500 controls the light source unit 202Y and the light source unit 202M provided in the light scanning device 200a, and the light source unit 202C and the light source unit 202Bk provided in the light scanning device 200b.

  The light source unit 202Y includes a circuit board 501Y. A semiconductor laser (LD) 502Y, a laser driver (LDD) 503Y, and a light receiving element (BD) 222a are mounted on the circuit board 501Y by solder. The light source unit 202C has the same configuration as that of the light source unit 202Y, and thus the description thereof is omitted.

  On the other hand, the light source unit 202M includes a circuit board 501M. A semiconductor laser (LD) 502M and a laser driver (LDD) 503M are mounted on the circuit board 501M by solder. The light source unit 202Bk has a configuration similar to that of the light source unit 202M, and thus the description thereof is omitted.

  The CPU 500 generates a PWM signal (PWM_Y, PWM_M, PWM_C, PWM_Bk) which is a drive signal for driving the semiconductor laser provided in each light source unit based on the input image data.

  The laser driver 503Y drives the semiconductor laser 502Y based on PWM_Y. The laser driver 503M drives the semiconductor laser 502M based on PWM_M. The laser driver 503C drives the semiconductor laser 502C based on PWM_C. The laser driver 503Bk drives the semiconductor laser 502Bk based on PWM_Bk.

The light receiving element 222a is emitted from the semiconductor laser 502M, by receiving been laser light _{L BD} reflected on the polygon mirror 209a generates a BD signal BD_YM, it outputs the BD_YM the controller 500. The light receiving element 222b is emitted from the semiconductor laser 502Bk, by receiving been laser light _{L BD} reflected on the polygon mirror 209b generates a BD signal BD_CBK, outputs the BD_CBk the controller 500.

FIG. 6 is a timing chart showing the generation timing of each signal in one scanning cycle of laser light. The controller 500 transmits the pulse _{M BD} where the timing with in one scanning cycle is PWM_M to the laser driver 503M. Laser driver 503M supplies a drive current to LD502M by receiving a pulse _{M BD.} The LD 502 M supplied with the drive current emits a laser beam, and the laser beam is deflected by the polygon mirror 209 a. The laser beam LBD deflected by the polygon mirror 209a scans the _BD 222a. The _BD 222 a scanned by the laser light LBD generates BD_YM, which is a horizontal synchronization signal shown in FIG. 6.

  The controller 500 transmits PWM_Y generated based on the input image data to the laser driver 503Y after a time Delay_Y (μsec) after BD_YM is generated. Further, the controller 500 transmits PWM_M generated based on the input image data to the laser driver 503M after a time Delay_M (μsec) after BD_YM is generated.

Similarly, the controller 500 transmits a pulse Bk _BD which is PWM_Bk to the laser driver 503Bk at a certain timing in one scanning cycle. The laser driver 503Bk supplies a drive current to the LD 502Bk by receiving the pulse Bk _BD . The LD 502Bk supplied with the drive current emits a laser beam, and the laser beam is deflected by the polygon mirror 209b. The laser beam LBD deflected by the polygon mirror 209 b scans the _BD 222 b. The _BD 222 b scanned by the laser light LBD generates BD_CBk, which is a horizontal synchronization signal shown in FIG.

  The controller 500 transmits PWM_C generated based on the input image data to the laser driver 503C after a time Delay_C (μsec) after BD_CBk is generated. Further, the controller 500 transmits PWM_Bk generated based on the input image data to the laser driver 503Bk after a time Delay_Bk (μsec) after BD_CBk is generated.

  The “image formation period” shown in FIG. 6 is a period in which the PWM signal generated based on the input image data is supplied to the laser driver. Each laser driver supplies a drive current to the semiconductor laser based on the supplied PWM signal. The phase relationship between BD_YM and BD_CBk is defined by the distance between the secondary transfer portions formed between each photosensitive drum and the intermediate transfer belt. Also, each of Delay_Y, Delay_M, Delay_C, and Delay_Bk is similarly defined by the distance between the secondary transfer portions formed between each photosensitive drum and the intermediate transfer belt.

  As described above, by controlling the transmission timing of the PWM signal from the controller 500 to each laser driver based on the BD signal, it is possible to substantially match the image writing position in the main scanning direction of the toner image of each color.

  Note that BD_YM and BD_CBk may be used to control the rotational speed of each polygon mirror to a target rotational speed by detecting the respective cycles. Alternatively, the phase relationship between BD_YM and BD_CBk may be detected, and the rotation phase relationship of the polygon mirror may be controlled so that the phase relationship between the two becomes the target phase difference.

  Subsequently, the light source units 202Y and 202C attached to the light scanning device 200 will be described with reference to FIGS. 4, 7 and 8. FIG. Since the light source unit 202Y and the light source unit 202C have the same configuration, the configuration will be described below using the light source unit 202Y.

  FIG. 7A is a perspective view of the circuit board 501Y and the laser holder 504Y. FIG. 7B is a perspective view of the laser holder 504Y viewed from the circuit board 501Y side. FIG. 8 is a perspective view showing the laser holder 504 Y attached to the optical box 201.

  An opening 505Y is formed in the laser holder 504Y. The semiconductor laser 502Y is pressed into the opening 505Y. As shown in FIG. 8, the laser holder 504Y is fixed to the side wall of the optical box 201 by fixing screws 506Y, 507Y, and 508Y.

  As shown in FIG. 7A, the laser holder 504Y includes a hollow barrel 509Y. Further, the laser holder 504Y is provided with a lens holding portion 511Y that holds the collimator lens 510Y on the tip end side of the lens barrel portion 509Y. The circuit board 501Y is attached to the optical box 201 by a fixing screw so as to face the rear surface of the surface from which the lens barrel 509Y protrudes. As shown in FIG. 7B, a terminal for supplying current from the semiconductor laser 502Y, a terminal for outputting a signal from a built-in photodiode for light amount monitoring (not shown), and a terminal for grounding are provided. The respective terminals are soldered to the circuit board 501Y.

  As mentioned above, FIG. 4 is an enlarged top view of the light scanning device. An opening is formed on the side wall of the optical box 201. When the light source unit 202Y is attached to the optical box 201, the barrel 509Y of the laser holder 504Y passes through the opening. Then, in a state where the laser holder 504 Y is fixed to the optical box 201, the lens barrel 509 Y is positioned inside the optical box 201.

As shown in FIG. 8, screw holes 221, 222, 223 and 224 for fastening fixing screws for fixing the circuit board 501Y to the optical box 201 are formed in the optical box 201. The screwing holes 221, 222, 223, 224 are erected from the side wall of the optical box 201 so as to surround the laser holder 504 Y fixed to the optical box 201. In addition, a through hole 225 for making _LBD incident is formed on the side wall of the optical box 201. The through holes 225 will be described in detail later.

  In the assembly process at the factory, the circuit board 501Y is fixed to the optical box 201 by the fixing screw in a state where the laser holder 504Y is fixed to the optical box 201. In the circuit board 501Y, three through holes into which three terminals of the semiconductor laser 502Y are inserted are formed. The terminals inserted into the three holes when fixing the circuit board 501Y to the optical box 201 are soldered to the circuit board 501Y. The three terminals are soldered to the circuit board 501Y, whereby the semiconductor laser 502Y and the laser driver 503Y are electrically connected. Circuit boards corresponding to other colors are attached to the optical box 201 in the same manner.

  FIG. 9 is a view showing the surface of the circuit board 501Y (501C) on the optical box 201 side. Electronic components such as various ICs, capacitors, resistors and the like are mounted on the circuit board 501Y, and wires for connecting the various electronic components are printed, but they are omitted in FIG. As shown in FIG. 9, a BD 222a is attached to the surface of the circuit board 501Y on the optical box 201 side. The BD 222 a includes the photoelectric conversion element 901 and a plurality of input / output terminals 902 connected to the circuit board 501 Y. The input / output terminal 902 is connected to the circuit board 501Y.

  As described above, the through hole 226 is formed in the side wall of the optical box 201. Moreover, as shown in FIG. 8, the protrusion part 226 which surrounds the through hole 225 over the perimeter is provided. The protrusion 226 protrudes from the side wall of the optical box 201 toward the outside of the optical box 201. The height of the projection 226 is about 2 mm. The optical box 201 and the circuit board 501Y are designed such that the BD 222a faces the opening surface of the through hole 225 (the surface surrounded by the top of the protrusion 226) in a state where the circuit board 501Y is fixed to the optical box 201. As shown in FIG. 8, the width between the outer peripheral surfaces of the protrusions 226 in the X axis direction is 7.5 mm, and the width between the outer peripheral surfaces of the protrusions 226 in the Z axis direction is 7 mm.

  A gap is generated between the circuit board 501Y and the opening surface of the through hole 225. From this gap, fine dust and gas that cause contamination of the optical components installed inside the optical box 222 may infiltrate. In order to reduce the amount of dust or gas entering the inside of the optical box 201, a seal member 512 (dust-proof member) is provided between the circuit board 501Y of the optical scanning device of this embodiment and the optical box 201. It is done.

  The seal member 512 will be described in detail below.

  FIGS. 10A and 10B are perspective views of the seal member 512. FIG. FIG.10 (c) is sectional drawing between A-A 'shown in FIG.10 (b). FIG. 10 (d) is a cross-sectional view taken along the line B-B 'shown in FIG. 10 (b). FIG. 10A shows the surface of the sealing member 512 on the circuit board side, and FIG. 10B shows the surface of the sealing member 512 on the optical box side.

  The seal member 512 is an elastic member (made of rubber) containing a rubber component. 512 in this embodiment is a silicone rubber. At least the seal member 512 is a member that is more flexible than the optical box 201 and the circuit board 501Y. In addition, since the sealing member 512 is a member that contacts the circuit board 501Y, it is preferable that the sealing member 512 be a flame retardant member.

The shape of the seal member 512 on the circuit board 501 side will be described with reference to FIG. A through hole 513 is provided at the center of the seal member 512. Inside the through hole 513, the light receiving portion of the BD 222a or at least the BD 222a is accommodated. As shown in FIG. 10A, the seal member 512 includes a first flat surface 514 ( third surface) and a second flat surface 515 (second surface). The first flat surface 514 is the top of a standing portion standing at a height of 0.3 mm from the second flat surface 515. That is, a step of 0.3 mm is formed between the first plane 514 and the second plane 515. The second plane 515 surrounds the through hole 513 along its entire circumference, and the first plane 514 surrounds the second plane 515 along its entire circumference.

Subsequently, the shape of the seal member 512 on the optical box 201 side will be described with reference to FIG. As shown in FIG. 10 (b), the seal member 512 includes a third flat surface 516 ( first surface), a fourth flat surface 517 (fourth surface), and a fifth flat surface 518. The seal member 512 is provided with a protrusion 519 protruding (elevated) from the third flat surface 516 and the fifth flat surface 518. The fourth plane 517 is the top of the protrusion 519. In the present embodiment, a portion between the protrusion 519 of the seal member and the opening 513 is referred to as a flexible portion 520 of the seal member 512. The through hole 513 is a through hole connecting the second flat surface 515 and the third flat surface 516 which is the back surface thereof.

  The fourth plane 517 protrudes 1.5 mm with respect to the third plane 516. That is, a step of 1.5 mm is formed between the fourth plane 517 and the third plane 516. The fourth plane 517 protrudes 1.5 mm with respect to the fifth plane 518. That is, a step of 1.5 mm is formed between the fourth plane 517 and the fifth plane 518.

  Then, the dimension of the seal member 512 in an A-A 'cross section is demonstrated using FIG.10 (c). The width of the through hole 513 is 4 mm. The width between the inner surfaces of the protrusions 519 is 7.5 mm, and the width between the outer surfaces is 12 mm. The width of the fourth plane 517 is 2.25 mm. The width of the seal member 512 is 15 mm.

  Then, the dimension of the seal member 512 in a B-B 'cross section is demonstrated using FIG.10 (d). The width of the through hole 513 is 4.5 mm. The width between the inner surfaces of the protrusions 519 is 7 mm, and the width between the outer surfaces is 12.5 mm. The width of the fourth plane 517 is 1.75 mm. The width of the seal member 512 is 15 mm.

  Next, a modification of the seal member 512 when the circuit board is attached to the optical box will be described with reference to FIG. FIG. 11A shows the shape of the seal member 512 before the circuit board is attached to the optical box 201, and shows a state in which the seal member 512 is not bent (state in which it is not deformed). FIG. 11B shows the shape of the seal member 512 after the circuit board is attached to the optical box 201.

  First, an operation process of attaching the circuit board 501Y to the optical box 201 will be described. The assembly worker attaches the protrusion 519 of the seal member 512 to the optical box 201 when attaching the circuit board 501Y to the optical box. That is, since the dimension of the inner surface of the projecting portion 519 on the side of the sealing member 512 substantially matches the dimension of the outer peripheral surface of the projecting portion 226 on the side of the optical box 201, as shown in FIG. The inner surface 519 (gripping portion) grips the outer peripheral surface of the protruding portion 226 of the optical box 201. The protrusion 519 of the seal member 512 grips the protrusion 226 of the optical box 201, whereby the seal member 512 is assembled to the optical box 201. With the sealing member 512 assembled to the optical box 201, the circuit board 501Y is fixed to the optical box 201 by a fixing screw (state of FIG. 11B).

  As shown in FIG. 11B, the first flat surface 514 of the seal member 512 contacts the circuit board 501Y over the entire circumference thereof. In addition, when the fourth flat surface 517 of the seal member 512 is pressed by the protruding portion 226 of the optical box 201, the flexible portion 520 is bent toward the circuit board 501 so as to fill the step of 0.3 mm described above. In the present embodiment, the flexible portion 520 is in contact with the circuit board 501Y over the entire circumference, but the flexible portion 520 may not be in contact with the circuit board 501.

  Since the sealing member of this embodiment is provided with 0.3 mm as described above, even if the flexible portion 520 is pressed by the projecting portion 226 of the optical box 201, the pressure applied to the circuit board 501Y by the flexible portion 520 has a level difference. Not smaller than the seal member 512. Therefore, the stress applied to the circuit board 501 is reduced by compressing the sealing member 512, and disconnection of the soldered portion of the BD 222a and the printed wiring on the circuit board due to the deformation of the circuit board 501 can be suppressed. On the other hand, the first flat surface 514 integrally formed in the flexible portion 520 is attached to the circuit substrate 501 by the flexible portion 520 infiltrating to the circuit board 501 side so as to fill the step of 0.3 mm. A biasing force acts. That is, the first flat surface 514 closely contacts the circuit board 501 following the deformation of the flexible member 520. Therefore, according to the seal member 512 of the present embodiment, the gap between the circuit board 501Y and the projection 226 of the optical box 201 can be filled while the pressure (stress) of the seal member 512 against the circuit board 501Y is reduced.

  FIG. 12 is a view showing a laser holder 1200 which is a modification of the laser holder 504. The laser holder 1200 is provided with a through hole 1201 and a protrusion 1202 at a position aligned with the through hole 225 of the optical box 201. The seal member 512 is assembled to the projecting portion 1202. In the case of the modified example shown in FIG. 12, a seal member for filling the gap between the laser holder 1200 and the optical box 201 is required, but the laser holder 1200 and the optical box 201 have higher rigidity than the circuit board. Since it is made of a material (plastic or metal member), deformation of the optical box 201 and the laser holder 1200 by compressing the seal member is allowed as compared with the circuit board.

  FIG. 13 is a view showing a seal member 1300 which is a modified example of the seal member 512. As shown in FIG. FIG. 13 is a view of the circuit board 501Y and the seal member 1300 as viewed in the Y-axis direction. As shown in FIG. 13, the example in which the seal member 512 is configured such that the input / output terminal 902 of the BD 222 a fits inside the through hole 513 has been described. On the other hand, the seal member 1300 shown in FIG. 13 is designed such that the flexible portion 1301 overlaps the input / output terminal 902 of the BD 222a. Since the pressure from the flexible portion 1301 to the BD 222a is small, the possibility of disconnection of the solder of the input / output terminals is reduced.

  As described above, by using the seal member of the present embodiment, it is possible to prevent the light scanning device from dust while suppressing stress on the seal member.

201 Optical box 222 BD
226 Protrusions 501 Circuit board 512 Seal member

Claims (14)

A light source for emitting a light beam for exposing a photosensitive member based on image data;
A rotating polygon mirror that deflects the light beam so that the light beam emitted from the light source scans on the photosensitive member;
A sensor comprising a light receiving element for receiving a light beam deflected by the rotary polygon mirror to generate a synchronization signal as a reference of the emission timing of the light beam from the light source based on the image data;
A circuit board on which the sensor is mounted, and on which a wiring to which an input / output terminal of the sensor is connected is printed;
A frame body including an optical box to which the rotary polygon mirror is attached, which penetrates from the inside to the outside of the optical box and through which the light beam deflected by the rotary polygon mirror is incident; A frame body on which the circuit board is attached from the outside of the optical box such that the light receiving element receives the light beam incident on the through hole. When,
An elastically deformable seal member made of rubber, which is interposed between the frame and the circuit board, and is in contact with the frame and the circuit board to fill the gap between the frame and the circuit board A seal member of the
The seal member is
A penetration having a first surface facing the frame and a second surface located on the back surface of the first surface and facing the circuit board, and communicating the first surface with the second surface A flexible portion formed with a hole and pressed and bent by the tip of the protrusion;
And a standing portion integrally formed on the seal member together with the flexible portion and extending over the entire circumference of the flexible portion on the side of the second surface;
The circuit board is attached to the optical box such that the light receiving element is disposed at a position surrounded by the through hole;
Between the second surface of the flexible portion and the circuit board in a non-bent state before the tip of the standing portion contacts the circuit board and the flexible portion is pressed by the projecting portion There is a gap in the
The circuit portion is formed on the standing portion integrally formed on the seal member together with the flexible portion by bending the flexible portion so as to be pressed by the tip of the projecting portion and to enter the gap. An optical scanning device characterized in that a biasing force acting toward the surface acts.   The seal member is integrally formed on the seal member together with the flexible portion, and includes a protruding portion that protrudes from the outside of the flexible portion on the first surface side, and the protruding portion is formed of the optical box The optical scanning device according to claim 1, wherein the projection is gripped.   The optical scanning device according to claim 1, wherein the flexible portion pressed by the projecting portion of the optical box abuts on an input / output terminal of the sensor.   The optical scanning device according to any one of claims 1 to 3, wherein the seal member contains rubber.   5. The optical scanning device according to claim 4, wherein the seal member is silicone rubber.   The optical scanning device according to claim 4, wherein the seal member is a flame-retardant member. A fixing screw for fixing the circuit board to the frame;
The seal member in a state in which a gap is formed between the second surface of the flexible portion and the circuit board is the seal member in response to the circuit board being fixed to the frame by the fixing screw. The optical scanning device according to any one of claims 1 to 6, wherein a bending portion is pressed to a tip end of the projecting portion and bends so as to enter the gap. The photosensitive body;
The optical scanning device according to any one of claims 1 to 7.
The electrostatic latent image formed on the photosensitive member by being exposed by the light beam is developed with toner, and the developed toner image is transferred to a recording medium and fixed. Image forming device. A light source for emitting a light beam for exposing a photosensitive member based on image data;
A rotating polygon mirror that polarizes the light beam so that the light beam emitted from the light source scans on the photosensitive member;
A sensor comprising a light receiving element for receiving a light beam deflected by the rotary polygon mirror to generate a synchronization signal as a reference of the emission timing of the light beam from the light source based on the image data;
A circuit board on which the sensor is mounted, and on which a wiring to which an input / output terminal of the sensor is connected is printed;
A frame body including an optical box to which the rotary polygon mirror is attached, which penetrates from the inside to the outside of the optical box and through which the light beam deflected by the rotary polygon mirror is incident; A frame body on which the circuit board is attached from the outside of the optical box such that the light receiving element receives the light beam incident on the through hole. When,
And a fixing screw for fixing the circuit board to the frame, which is used in an optical scanning device, and is disposed between the frame and the circuit board fixed to the frame by the fixing screw. An elastically deformable seal member,
A penetration having a first surface facing the frame and a second surface located on the back surface of the first surface and facing the circuit board, and communicating the first surface with the second surface A flexible portion formed with a hole and pressed and bent by the tip of the protrusion;
And an erected portion integrally formed on the seal member together with the flexible portion and extending over the entire outer periphery of the flexible portion on the side of the second surface;
The circuit board is attached to the optical box by the fixing screw such that the light receiving element is disposed at a position surrounded by the through hole.
Between the second surface of the flexible portion and the circuit board in a non-bent state before the tip of the standing portion contacts the circuit board and the flexible portion is pressed by the projecting portion Form a gap in the
The circuit portion is formed on the standing portion integrally formed on the seal member together with the flexible portion by bending the flexible portion so as to be pressed by the tip of the projecting portion and to enter the gap. A sealing member characterized by applying a biasing force that biases it toward a head. The seal member is integrally formed on the seal member together with the flexible portion, and includes a protruding portion that protrudes from the outside of the flexible portion on the first surface side, and the protruding portion is a portion of the optical box The seal member according to claim 9, wherein the protrusion is gripped. The seal member according to claim 9 or 10, wherein the flexible portion pressed by the projecting portion of the optical box abuts on an input / output terminal of the sensor. The seal member according to any one of claims 9 to 11, containing rubber. The seal member according to claim 12, which is a silicone rubber. The seal member according to claim 12, which is a flame retardant member.

Images