Scanning optical apparatus and image forming apparatus

Abstract

To improve assembly quality of a cover member of a scanning optical device with an inexpensive configuration while protecting a circuit board.SOLUTION: A scanning optical device includes an optical box 9, a cover member 20, a first side wall 9b, a second side wall 9c, a through-hole 19, a first side face 39, a second side face 29, a substrate protection part 23, a regulation part 24, a first end 35, a second end 25, a first insertion part 21a, and a second insertion part 21b. A distance X between the second end 25 and the second side face 29 in a normal direction of a circuit board 15 is smaller than a distance Y between an electrical element in the most proximity to the substrate protection part 23 of the electrical elements mounted to the circuit board 15 and the substrate protection part 23 while the first insertion part 21a and the second insertion part 21b are inserted into the through-hole 19.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a scanning optical device, an image forming apparatus, and a method for assembling a scanning optical device, and more particularly to a scanning optical device that performs optical writing using a laser beam in an image forming apparatus such as a laser beam printer, a digital copier, or a digital facsimile. [Background technology]

[0002] As a scanning optical device used in an electrophotographic image forming apparatus, there is a device that deflects a light beam emitted from a semiconductor laser by a rotating polygon mirror and guides the deflected light beam onto a photoconductor by optical components such as lenses and mirrors. As a result, an electrostatic latent image is formed on the photoconductor (see, for example, Patent Document 1). Such a scanning optical device is configured such that a part of a cover member of the scanning optical device is extended and the variable resistor on the circuit board is covered at the extended part. In a configuration in which a driving circuit board for a semiconductor laser is mounted in an exposed state outside a housing (hereinafter referred to as an optical box), packaging materials, the hands and clothes of an operator, etc. may come into contact with the circuit board when the scanning optical device is transported or when the scanning optical device is installed inside a laser beam printer. When the packaging material, etc. comes into contact with a variable resistor on the circuit board that adjusts the amount of laser light, the amount of light may change, causing poor image density, etc. As a countermeasure, a configuration has been adopted in which a part of a cover member of the scanning optical device is extended and the variable resistor on the circuit board is covered at the extended part, thereby preventing contact with the variable resistor and preventing fluctuations in the amount of laser light. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6376856 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional example, a protective portion provided on the cover member and covering the variable resistor comes into contact with the circuit board when the cover member is assembled, which causes a problem that electrical elements and the like on the circuit board are damaged.

[0005] The present invention has been made under these circumstances, and an object of the present invention is to improve the assembly quality of a cover member for a scanning optical device with an inexpensive configuration while protecting a circuit board. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the present invention has the following configuration.

[0007] (1) A scanning optical device comprising: a light source; a deflection means for deflecting a light beam emitted from the light source; a housing having a bottom on which the deflection means is disposed and a sidewall erected from the bottom; a circuit board provided on the sidewall in a state exposed to the outside of the housing and on which an electrical element for driving the light source is mounted; and a cover member for closing an opening formed by the sidewall, wherein the sidewall has a first sidewall on which the circuit board is disposed and a second sidewall parallel to a normal direction of the circuit board, the second sidewall having a long through hole in the normal direction, a first side surface forming a side of the through hole closer to the circuit board, and a second side surface forming a side of the through hole farther from the circuit board, and the cover member closes the housing. and a regulating portion that blocks the through hole when the cover member closes the housing, the regulating portion having a first end portion closer to the first side surface and a second end portion closer to the second side surface, wherein the regulating portion has a first insertion portion that is provided near the first end portion and inserted into the through hole when the cover member is assembled to the housing, and a second insertion portion that is provided near the second end portion and inserted into the through hole when the cover member is assembled to the housing, and wherein when the first insertion portion and the second insertion portion are inserted into the through hole, a distance in the normal direction between the second end portion and the second side surface is smaller than a distance between the protective portion and an electrical element among the electrical elements that is closest to the protective portion.

[0008] (2) An image forming apparatus comprising: a scanning optical device as described in (1); an image carrier on which an electrostatic latent image is formed by the scanning optical device; a developing means for developing the electrostatic latent image formed on the image carrier with a developer to form a developer image; and a transfer means for transferring the developer image to a recording material. Effect of the Invention

[0009] According to the present invention, it is possible to improve the assembly quality of the cover member of the scanning optical device with an inexpensive configuration while protecting the circuit board. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram for explaining the configuration of a scanning optical device according to an embodiment of the present invention; [Diagram 2] FIG. 1 is a diagram illustrating the configuration of a cover member and an optical box according to an embodiment. [Diagram 3] FIG. 13 is a diagram illustrating the assembly of the cover member according to the embodiment; [Figure 4] FIG. 13 is a diagram illustrating the assembly of the cover member according to the embodiment; [Diagram 5] FIG. 2 is an enlarged front view of a scanning optical device according to an embodiment of the present invention; [Figure 6] FIG. 1 is a diagram showing the scanning optical device of the embodiment as viewed from the side of the circuit board. [Figure 7] FIG. 3 is a view of the scanning optical device according to the embodiment as seen from the direction of the arrow F in FIG. [Figure 8] FIG. 1 is a diagram showing an image forming apparatus according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings by way of examples. EXAMPLES

[0012] [Scanning optical device] An embodiment of a scanning optical device according to the present invention will be specifically described with reference to Fig. 1 to Fig. 7. Fig. 1 is a perspective view showing the configuration of a scanning optical device 101 of this embodiment. The scanning optical device 101 shown in Fig. 1 forms an electrostatic latent image on the surface of a photosensitive drum 8, which is an image carrier, by using a laser beam in an image forming device such as a laser beam printer, a digital copier, or a facsimile. The scanning optical device 101 has a semiconductor laser unit 1, which is a light source that emits a laser beam L (two-dot chain line), and an anamorphic collimator lens 2 in which a collimator lens and a cylindrical lens are integrally molded.

[0013] The scanning optical device 101 has a main scanning aperture 3 formed of a through groove, and a rotating polygon mirror 4. The rotating polygon mirror 4 has a reflecting surface 12, and for example, in this embodiment, the reflecting surface 12 is four. The reflecting surface 12 of the rotating polygon mirror 4 is not limited to four. The scanning optical device 101 has an optical deflector 5, which is a deflection means that rotates the rotating polygon mirror 4 by a motor that is a drive source. The scanning optical device 101 has a beam detector (hereinafter, referred to as BD) 6, which is a detection means of the laser beam L deflected and scanned by the optical deflector 5, in order to determine the writing start position of the laser beam L (light beam) on the surface of the photosensitive drum 8. The scanning optical device 101 has a scanning lens 7, which is an imaging means that images the deflected and scanned laser beam L on the surface of the photosensitive drum 8, and a folding mirror 10 that deflects the laser beam L that has passed through the scanning lens 7 toward the photosensitive drum 8.

[0014] The scanning optical device 101 has an optical box 9, which is a housing that houses each optical member including the optical deflector 5. The optical box 9 is made of, for example, black resin and is formed by injection molding. The optical box 9 has an exit port 13 for emitting the laser light beam L from inside the scanning optical device 101 toward the photosensitive drum 8. The arrow B indicates the main scanning direction described later. The optical box 9 has an optical deflector 5, i.e., a rotating polygon mirror 4, disposed on a bottom 9a. The optical box 9 has side walls erected from the bottom 9a. The side walls include a first side wall 9b on which a circuit board 15 described later is disposed, a second side wall 9c (see FIG. 3) parallel to the normal direction of the circuit board 15, and a third side wall 9d (see FIG. 2) opposed to the second side wall 9c. An opening of the optical box 9 is formed by the side walls, and the cover member 20 closes this opening. The rotary polygon mirror 4 is provided near the third side wall 9d (see FIG. 2).

[0015] [Operation of scanning optical device] The direction in which the laser beam L is scanned by the optical deflector 5 is defined as the main scanning direction, and the direction perpendicular to the main scanning direction is defined as the sub-scanning direction. The operation of the scanning optical device 101 will be described below. The laser beam L emitted from the semiconductor laser unit 1 is made into a substantially parallel beam or a convergent beam in the main scanning direction by the anamorphic collimator lens 2, and made into a convergent beam in the sub-scanning direction. Next, the beam width of the laser beam L in the main scanning direction is limited by the main scanning aperture 3. The beam width in the sub-scanning direction is limited by an opening hole (sub-scanning aperture, not shown) located upstream of the anamorphic collimator lens 2. The beam that passes through the sub-scanning aperture, the anamorphic collimator lens 2, and the main scanning aperture 3 is imaged on the reflecting surface 12 of the rotating polygon mirror 4 in the form of a focal line that extends long in the main scanning direction. The laser beam L imaged on the reflecting surface 12 of the rotating polygon mirror 4 is deflected and scanned by the rotating polygon mirror 4 that rotates in the direction of the arrow A. The deflected laser beam L scans the BD 6 in the main scanning direction.

[0016] Next, the deflected and scanned laser beam L enters the scanning lens 7. The laser beam L focused on the rotating polygon mirror 4 in a focal line becomes a spot of several mm on the scanning lens 7 and passes through the scanning lens 7. The laser beam L that passes through the scanning lens 7 is deflected by the folding mirror 10 and is emitted from the emission port 13 to the outside of the scanning optical device 101. The emitted laser beam L scans in the direction of arrow B in FIG. 1 while finally focusing a spot on the photosensitive drum 8. Here, the photosensitive drum 8 is rotated around its cylindrical axis (rotation axis) to perform sub-scanning. As a result, an electrostatic latent image according to image information is formed on the surface of the photosensitive drum 8 that is uniformly charged by a charging means (not shown).

[0017] [Optical box] 2 is an explanatory diagram of a support portion of the optical box 9 that supports the cover member 20 in the scanning optical device 101 of this embodiment. The scanning optical device 101 has the cover member 20 that closes the opening of the optical box 9 that houses each optical member.

[0018] The optical box 9 has support parts 31, 32, 33, and 34 that support the cover member 20, and fixing parts 41, 42, 43, and 44 that fix the optical box 9 to a frame (not shown) of the laser beam printer. The support parts 31, 32, 33, and 34 are provided near the fixing parts 41, 42, 43, and 44, respectively. When the cover member 20 is attached to the optical box 9, it is supported by the optical box 9 at four points, that is, the support parts 31, 32, 33, and 34.

[0019] [Cover component assembly process] Next, the assembly process of the cover member 20 of this embodiment will be described with reference to Figures 3 and 4. Figure 3 is a perspective view showing how the cover member 20 of this embodiment is assembled to the optical box 9, and is a view of the scanning optical device 101 viewed from the direction of the arrow M in Figure 2. A circuit board 15 for driving the semiconductor laser is attached to the outer side of the first side wall 9b of the optical box 9 and is exposed to the outside of the scanning optical device 101. A through hole 19 is provided in the second side wall 9c of the optical box 9 in addition to the exit port 13 from which the laser light beam L is emitted, and the through hole 19 has an elongated shape in the main scanning direction (the direction of the arrow E in Figure 3) like the exit port 13. The second side wall 9c of the optical box 9 has a first side surface 39 and a second side surface 29 that form both ends of the through hole in the direction of the arrow E. In the main scanning direction, the first side surface 39 is the side surface of the through hole 19 closer to the circuit board 15, and the second side surface 29 is the side surface of the through hole 19 farther from the circuit board 15. Hereinafter, the second side surface 29 is also referred to as the side surface 29 on the anti-circuit board side.

[0020] The cover member 20 has a first insertion portion 21a and a second insertion portion 21b. The first insertion portion 21a is provided so as to be located near the circuit board 15 when the cover member 20 closes the optical box 9. The second insertion portion 21b is provided so as to be located away from the circuit board 15 when the cover member 20 closes the optical box 9. The first insertion portion 21a and the second insertion portion 21b are inserted into the through hole 19 of the optical box 9, and function to prevent the cover member 20 from coming off after assembly.

[0021] Moreover, the cover member 20 has a restricting portion 24, and the first insertion portion 21a and the second insertion portion 21b are provided in the restricting portion 24. The restricting portion 24 has a first end portion 35 and a second end portion 25. The first end portion 35 is one end portion of the restricting portion 24 in the vicinity of the first insertion portion 21a, and is an end portion that is closer to the circuit board 15 when the cover member 20 is assembled to the optical box 9. The second end portion 25 is the other end portion of the restricting portion 24 in the vicinity of the second insertion portion 21b, and is an end portion that is farther from the circuit board 15 when the cover member 20 is assembled to the optical box 9. Hereinafter, the second end portion 25 is also referred to as the end portion 25 on the anti-circuit board side.

[0022] (1st step) A first step of the method of assembling the cover member 20 to the optical box 9 (a method of assembling a scanning optical device) will be described with reference to Fig. 3. First, as shown by the dashed arrow C in Fig. 3, the first insertion portion 21a and the second insertion portion 21b of the cover member 20 are inserted into the through hole 19 of the optical box 9. At this time, as shown in Fig. 3, the cover member 20 is inclined with respect to the optical box 9. When the first insertion portion 21a and the second insertion portion 21b are inserted into the through hole 19, the first end portion 35 and the end portion 25 on the anti-circuit board side are restricted by the first side surface 39 and the side surface 29 on the anti-circuit board side to a direction perpendicular to the surface of the circuit board 15 (the direction of the arrow E in Fig. 3) (the normal direction).

[0023] Fig. 4 is a perspective view showing a state in which the first insertion portion 21a and the second insertion portion 21b of the cover member 20 are inserted into the through hole 19 of the optical box 9 as described in Fig. 3, and shows a state in which the cover member 20 is in the middle of being assembled to the optical box 9. Fig. 4 is also a view seen from the direction of arrow F in Fig. 2. In this state, the cover member 20 is maintained in an inclined state with respect to the optical box 9, with the first insertion portion 21a and the second insertion portion 21b inserted (fitted) into the through hole 19 of the optical box 9.

[0024] The cover member 20 has a locking portion 22, which functions to prevent the cover member 20 from coming off after assembly. A through hole 26 is provided in the locking portion 22. The optical box 9 has a protrusion 11 that protrudes outward from the surface of the third side wall 9d, and the protrusion 11 is inserted into the through hole 26 when the cover member 20 closes the opening of the optical box 9.

[0025] The circuit board 15 is fixed to the optical box 9 by screws 27. The circuit board 15 is fixed by the screws 27 in a state where it is exposed to the outside of the optical box 9. The driving IC 16 is an IC for driving the semiconductor laser mounted on the circuit board 15. A variable resistor 17 for adjusting the light amount of the semiconductor laser is mounted on the circuit board 15.

[0026] The cover member 20 has a board protection portion 23 (protection portion), which prevents external contact with electric elements such as the driving IC 16 and the variable resistor 17 after the cover member 20 is assembled to the optical box 9. The cover member 20 has a positioning groove 46 and an anti-rotation groove 47. On the other hand, the optical box 9 has a positioning portion 36 and an anti-rotation groove 37.

[0027] (2nd process) A second step of the method of assembling the cover member 20 to the optical box 9 will be described with reference to FIG. 4. After the first step, the cover member 20 can be closed by rotating it toward the optical box 9 in the direction of arrow R with the above-mentioned first insertion portion 21a, second insertion portion 21b, and through hole 19 as the rotation axis. As shown by the dashed arrow D, the locking portion 22 is moved so as to ride on the protrusion 11, and finally, the protrusion 11 is inserted into the through hole 26. As the locking portion 22 rides on the protrusion 11 while deforming, when the through hole 26 moves to the same height as the protrusion 11, the protrusion 11 is naturally inserted into the through hole 26, and the locking portion 22 and the protrusion 11 are locked together, and assembly can be easily completed.

[0028] 3, the cover member 20 is restricted in a direction perpendicular to the surface of the circuit board 15 (the direction of arrow E in FIGS. 3 and 4) (the normal direction) by the first end 35 and the first side surface 39, and the second end 25 and the second side surface 29. Therefore, during the process of assembling the cover member 20, the board protection part 23 does not come into contact with the circuit board 15 or electric elements mounted thereon, such as the driving IC 16 and the variable resistor 17.

[0029] The final positional relationship between the optical box 9 and the cover member 20 (the direction of arrow E in FIG. 4 and the direction of arrow K perpendicular to arrow E) is determined by fitting the positioning groove 46 and the positioning portion 36 together and inserting the anti-rotation groove 37 into the anti-rotation groove 47 (dashed arrow J). Through the above first and second steps, the opening of the optical box 9 can be closed by the cover member 20 without the board protection portion 23 coming into contact with the variable resistor 17 on the circuit board 15 and the like.

[0030] [Restriction in the direction of arrow E] As described above, the most characteristic configuration of the scanning optical device 101 in which the cover member 20 is coupled to the optical box 9 will be described. Specifically, the relationship between the distance between the end portion 25 on the side opposite to the circuit board of the restricting portion 24 and the side surface 29 on the side opposite to the circuit board of the through hole 19, and the distance between the substrate protection portion 23 and the components mounted on the circuit board 15 will be described with reference to FIGS. 5 and 6.

[0031] FIG. 5(a) is a partially enlarged view of the scanning optical device 101 with the cover member 20 assembled, as viewed from the direction of arrow M in FIG. 2. That is, it is an enlarged view of the right side portion of FIG. 3. For easy understanding, a partial cross-sectional view of the cross-section indicated by the dashed-dotted line in FIG. 5(a) as viewed from arrow H is also shown as FIG. 5(b). Here, let the distance between the end portion 25 on the side opposite to the circuit board of the restricting portion 24 and the side surface 29 on the side opposite to the circuit board of the through hole 19 be X.

[0032] Note that by closing the through hole 19 with the restricting portion 24, the inflow and outflow amounts of air entering and leaving the scanning optical device 101 can be reduced. By reducing the inflow and outflow amounts of air, the possibility of dust floating in the air adhering to optical elements such as the rotating polygon mirror 4 can be reduced. When dust adheres to the optical element, the light amount may locally decrease in the main scanning direction, and density unevenness may occur in the printed matter.

[0033] FIG. 6 is a view of the scanning optical device 101 of the present embodiment as viewed from the side of the circuit board 15 (in the direction of arrow F in FIG. 2). Let the distance between the substrate protection portion 23 and the element (for example, the drive IC 16) that is closest among the electrical elements in the range covered by the substrate protection portion 23 be Y. In the present embodiment, although the distance Y is the distance between the drive IC 16 and the substrate protection portion 23, it is not limited to the drive IC and is the distance to the closest electrical element. In the present embodiment, the relationship X < Y holds.

[0034] Here, when the substrate protection portion 23 moves in the direction approaching the circuit board 15 (the direction toward the left in FIG. 6) in the normal direction (arrow E direction) of the circuit board 15, the second end portion 25 of the restricting portion 24 abuts against the second side surface 29, thereby restricting the movement in the approaching direction. For this reason, since the distance X between the second end portion 25 and the second side surface 29 is smaller than the distance Y, the substrate protection portion 23 does not interfere with the electrical elements on the circuit board 15. When the substrate protection portion 23 moves in the direction away from the circuit board 15 (the direction toward the right in FIG. 6) in the normal direction of the circuit board 15, the movement in the separating direction is restricted by the first end portion 35 of the restricting portion 24 abutting against the first side surface 39.

[0035] In a configuration satisfying the above relationship, when assembling the cover member 20, in the process of inserting the insertion portion 21 into the through hole 19 and then inserting the protrusion portion 11 into the through hole 26 of the locking portion 22, the substrate protection portion 23 and the electrical element closest to the substrate protection portion 23 do not come into contact. The electrical element closest to the substrate protection portion 23 is the drive IC 16 in this embodiment. That is, first, the first insertion portion 21a and the second insertion portion 21b are inserted into the through hole 19, and the movement in the arrow E direction, particularly the movement of the substrate protection portion 23 in the direction approaching the circuit board 15, is restricted to the distance Y (<X). For this reason, the substrate protection portion 23 and the electrical elements on the circuit board 15 do not come into contact during the assembly process.

[0036] FIG. 7 is an explanatory view of the scanning optical device 101 with the cover member 20 assembled, as viewed from the direction of arrow F in FIG. 2. The portions 53 and 54 are part of the cover member 20 and are supported by the support portion 33 (first support portion) and the support portion 34 (second support portion) of the optical box 9 described in FIG. 2, and are the locations where nodes of vibration occur when the cover member 20 vibrates. The portion 55 is in the middle of the portions 53 and 54 (nodes of vibration) and is the location where an antinode of vibration occurs when the cover member 20 vibrates.

[0037] The cover member 20 is assembled to the optical box 9 in a state where the locking portion 22 is pulled in the direction of arrow G (stress is generated) by the protruding portion 11 provided on the optical box 9. Since the protruding portion 11 that generates stress is near the portion 55 that is the antinode of vibration, the vibration of the cover member 20 can be effectively suppressed.

[0038] Also, as shown in FIG. 2, the protruding portion 11 is provided on the third side wall 9d of the outer wall of the optical box 9 that is closest to the rotating polygon mirror 4. By assembling the protruding portion 11 to the optical box 9 in a state where the locking portion 22 of the cover member 20 is pulled in the direction of arrow G, it is possible to increase the sealing degree of the cover member 20 with respect to the optical box 9. As a result, leakage of noise generated by the rotation of the rotating polygon mirror 4 to the outside can be reduced.

[0039] In this embodiment, the gap (Y) between the through hole 19 provided in the optical box 9 and the side surface 29 on the side opposite to the circuit board of the cover member 20 is smaller than the distance (X) between the electrical element mounted on the circuit board 15 and the cover member 20 that covers it (Y < X). Therefore, when assembling the cover member 20, the substrate protection portion 23 can maintain stable quality without damaging electrical elements on the circuit board or the like.

[0040] [Image forming apparatus] FIG. 8 shows a schematic configuration of a laser beam printer as an example of an image forming apparatus. The laser beam printer 1000 (hereinafter referred to as the printer 1000) includes a photosensitive drum 1010, a charging unit 1020, and a developing unit 1030 that is a developing means. The photosensitive drum 1010 is an image carrier on which an electrostatic latent image is formed, and corresponds to the photosensitive drum 8 described above. The charging unit 1020 uniformly charges the photosensitive drum 1010. The scanning optical device 1025, which is an exposure means, forms an electrostatic latent image by scanning the photosensitive drum 1010 with laser light according to image data. Note that the scanning optical device 1025 is shown in a simplified manner in FIG. 8. The scanning optical device 1025 corresponds to the scanning optical device 101 of the embodiment. The developing unit 1030 forms a toner image, which is a developer image, by developing the electrostatic latent image formed on the photosensitive drum 1010 with toner, which is a developer.

[0041] A toner image formed on the photosensitive drum 1010 (on the image carrier) is transferred by a transfer unit 1050, which is a transfer means, to a sheet P, which is a recording material supplied from a cassette 1040. Then, the unfixed toner image transferred to the sheet P is fixed by a fixing device 1060 and discharged onto a tray 1070. The photosensitive drum 1010, charging unit 1020, developing unit 1030, and transfer unit 1050 constitute an image forming unit. The printer 1000 also includes a power supply device 1080, which supplies power to a drive unit such as a motor and a control unit 5000. The control unit 5000 has a CPU (not shown) and controls the image forming operation by the image forming unit, the conveying operation of the sheet P, and the like.

[0042] When the printer 1000 finishes a print operation, after a predetermined time has elapsed, the printer 1000 transitions to a standby state in which the printer can immediately perform a print operation. After a further predetermined time has elapsed, the printer 1000 transitions from the standby state to a sleep state, which is a low power consumption mode, in order to reduce power consumption during standby. The printer 1000 has three states: a sleep state and a standby state, which are second modes, and a print state, which is a first mode, and the control unit 5000 transitions the printer 1000 to each of these states. Note that the image forming apparatus to which the scanning optical device 101 of the embodiment can be applied is not limited to the configuration exemplified in FIG. 8.

[0043] As described above, according to this embodiment, it is possible to improve the assembly quality of the cover member of the scanning optical device with an inexpensive configuration while protecting the circuit board. [Explanation of symbols]

[0044] 9b 1st side wall 9c 2nd side wall 19 Through hole 23 Board protection section 24 Regulatory Department 25 Second end 29 Second aspect 35 First end 39 First aspect

Claims

1. Light source and A deflection means for deflecting the light beam emitted from the light source, A housing having a bottom on which the deflection means is arranged, and side walls erected from the bottom, A circuit board is provided on the side wall of the housing, exposed to the outside, and on which a plurality of electrical elements for driving the light source are mounted. A cover member that closes the opening of the housing formed by the side wall, In a scanning optical apparatus having, The side wall comprises a first side wall on which the circuit board is provided, and a second side wall parallel to the plane of the circuit board in a direction perpendicular to the plane of the circuit board. The second side wall has a through hole that is elongated in a direction perpendicular to the plane, a first side surface that forms the side of the through hole closer to the circuit board, and a second side surface that forms the side of the through hole further away from the circuit board. The cover member comprises a protective portion that protects the circuit board when the cover member closes the opening, and a restricted portion that is positioned corresponding to the through hole when the cover member closes the opening, and the restricted portion having a first end on the side closer to the first side and a second end on the side closer to the second side. The restricted portion includes a first insertion portion provided near the first end and inserted into the through hole when the cover member is assembled to the housing, and a second insertion portion provided near the second end and inserted into the through hole. A scanning optical apparatus characterized in that, with the first insertion portion and the second insertion portion inserted into the through hole, the distance between the second end and the second side surface in a direction perpendicular to the plane is smaller than the distance between the electrical element closest to the protective portion among the plurality of electrical elements and the protective portion.

2. The scanning optical apparatus according to claim 1, characterized in that the direction perpendicular to the plane is the main scanning direction of the light beam by the deflection means.

3. The housing has a third side wall opposite to the second side wall, The third side wall has a projection, The scanning optical apparatus according to claim 1, characterized in that the cover member has a locking portion that engages with the projection portion when the first insertion portion and the second insertion portion are inserted into the through hole.

4. The housing has a first support portion and a second support portion that support the cover member, arranged in a direction parallel to the direction perpendicular to the plane near the third side wall. The scanning optical apparatus according to claim 3, characterized in that the locking portion is provided so as to be located midway between the first support portion and the second support portion in a direction perpendicular to the plane.

5. The first support portion and the second support portion become nodes of the vibration when the scanning optical device vibrates. The scanning optical apparatus according to claim 4, characterized in that the locking portion is provided at a position that is an antinode of the vibration.

6. The scanning optical apparatus according to claim 3, characterized in that the deflection means is provided at a position closer to the third side wall than to the second side wall.

7. A scanning optical apparatus according to claim 1, An image carrier, which is scanned by a light beam emitted from the scanning optical device, thereby forming an electrostatic latent image, A developing means for developing the electrostatic latent image formed on the image carrier with a developer to form a developer image, A transfer means for transferring the developer image onto a recording material, An image forming apparatus characterized by comprising:

8. A light source, A deflection means for deflecting the light beam emitted from the light source, A housing having a bottom on which the deflection means is arranged, and side walls erected from the bottom, A circuit board is provided on the side wall of the housing, exposed to the outside, and on which a plurality of electrical elements for driving the light source are mounted. A cover member that closes the opening of the housing formed by the side wall, In a scanning optical apparatus having, The side wall comprises a first side wall on which the circuit board is provided, and a second side wall parallel to the direction intersecting the plane of the circuit board. The second side wall has a through hole that is elongated in a direction intersecting the plane, a first side surface that forms the side of the through hole closer to the circuit board, and a second side surface that forms the side of the through hole further away from the circuit board. The cover member comprises a protective portion that protects the circuit board when the cover member closes the opening, and a restricted portion that is positioned corresponding to the through hole when the cover member closes the opening, and the restricted portion having a first end on the side closer to the first side and a second end on the side closer to the second side. The restricted portion has an insertion portion that is inserted into the through hole, A scanning optical device characterized in that, with the insertion portion inserted into the through hole, the distance between the second end and the second side surface in a direction perpendicular to the plane is smaller than the distance between the electrical element closest to the protection portion among the plurality of electrical elements and the protection portion.

9. The scanning optical apparatus according to claim 8, characterized in that the direction perpendicular to the plane is the main scanning direction of the light beam by the deflection means.

10. The housing has a third side wall opposite to the second side wall, The third side wall has a projection, The scanning optical apparatus according to claim 8, characterized in that the cover member has a locking portion that engages with the projection portion when the insertion portion is inserted into the through hole.

11. The housing has a first support portion and a second support portion that support the cover member, arranged in a direction parallel to the direction perpendicular to the plane near the third side wall, The scanning optical apparatus according to claim 10, characterized in that the locking portion is provided so as to be located midway between the first support portion and the second support portion in a direction perpendicular to the plane.

12. The scanning optical apparatus according to claim 10, characterized in that the deflection means is provided at a position closer to the third side wall than to the second side wall.

13. A scanning optical apparatus according to claim 8, An image carrier, which is scanned by a light beam emitted from the scanning optical device, thereby forming an electrostatic latent image, A developing means for developing the electrostatic latent image formed on the image carrier with a developer to form a developer image, A transfer means for transferring the developer image onto a recording material, An image forming apparatus characterized by comprising:

Images