Scanning optical apparatus and image forming apparatus

Abstract

To provide a scanning optical device capable of suppressing deformation of a light shielding wall, and an image forming apparatus.SOLUTION: The scanning optical device includes light sources LM1 and LM2, a deflector 50, a scanning optical system 60YM having a scanning lens Lo1 on which a beam BY deflected by the deflector 50 is incident, a scanning optical system 60CK having a scanning lens Lo2 on which a beam BK deflected by the deflector 50 is incident, a frame 100 having a frame base wall 110 on which the deflector 50 is installed, and a cover that covers the deflector 50 from a side opposite to the frame base wall 110 and is made of a softer material than the frame 100. The cover includes the first light blocking wall 220 that blocks the stray beam BY1 generated by the beam 60YM being reflected by the incident surface 61 of the scanning lens BY2 from reaching the scanning lens 60CK, and that is at least partially located between the scanning lens 60YM and the scanning lens 60CK, and the reinforcing wall 230 that extends in the direction intersecting the first light blocking wall 220 and is connected to the first light blocking wall 220.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a scanning optical device and an image forming device. [Background technology]

[0002] A conventional scanning optical device is known that includes a plurality of light source devices that emit beams, a deflector that deflects the beams, a first scanning optical system that includes a first scanning lens, a second scanning optical system that includes a second scanning lens and is symmetrical to the first scanning optical system with the deflector at the center, a frame to which the deflector is fixed, and a cover that covers the deflector between the frame (Patent Document 1). Figure 5 of Patent Document 1 discloses, for example, a device in which a light-shielding wall that blocks the beam reflected by the incident surface of the first scanning lens is molded integrally with a case so that the beam reflected by the incident surface of the first scanning lens does not enter the second scanning lens. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-076566 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if the cover is made of a resin that is softer than the frame, the light-shielding wall is likely to deform. Therefore, it is desirable to be able to suppress deformation of the light-shielding wall. [Means for solving the problem]

[0005] The scanning optical device includes a first light source device, a second light source device, a deflector, a first scanning optical system, a second scanning optical system, a frame, and a cover. The first light source device emits a first beam. The second light source device emits a second beam. The deflector deflects the first beam and the second beam and includes a polygon mirror rotatable about a rotation axis extending in the first direction. The first scanning optical system forms an image of the first beam deflected by the deflector on a first scanned surface, and has a first scanning lens onto which the first beam deflected by the deflector is incident. The second scanning optical system forms an image of the second beam deflected by the deflector on a second scanned surface. The second scanning optical system is located on the opposite side of the polygon mirror from the first scanning lens in a second direction perpendicular to the first direction, and has a second scanning lens onto which the second beam deflected by the deflector is incident. The frame has a frame base wall on which the deflector is mounted. The cover has a cover base wall that covers the deflector from the opposite side to the frame base wall in the first direction. The cover is made of a resin that is softer than the frame. The cover has a first light-shielding wall and a reinforcing wall. The first light-shielding wall blocks first stray light generated when the first beam is reflected by the incident surface of the first scanning lens from reaching the second scanning lens. The first light-shielding wall protrudes from the cover base wall toward the frame base wall, and at least a portion of the first light-shielding wall is located between the first scanning lens and the second scanning lens when viewed from the first direction. The reinforcing wall protrudes from the cover base wall toward the frame base wall, extends in a direction intersecting the first light-shielding wall, and is connected to the first light-shielding wall.

[0006] The cover has a reinforcing wall that extends in a direction intersecting the first light-shielding wall and is connected to the first light-shielding wall, so that the cover, which is made of a resin softer than the frame, has the first light-shielding wall, thereby suppressing deformation of the first light-shielding wall.

[0007] The reinforcing wall may include a first reinforcing wall whose dimension in the first direction decreases with increasing distance from the first light-shielding wall.

[0008] The reinforcing wall includes a first reinforcing wall whose dimension in the first direction decreases with increasing distance from the first light-shielding wall, thereby making it possible to suppress interference between the first reinforcing wall and the beam.

[0009] The cover may have ribs that project from the cover base wall toward the frame base wall. The reinforcing wall may include a second reinforcing wall connected to the rib.

[0010] By including a second reinforcing wall connected to the rib, the second reinforcing wall can be reinforced by the rib, and therefore deformation of the first light-shielding wall can be further suppressed by the second reinforcing wall.

[0011] The first light-shielding wall may protrude in the first direction to a position closer to the frame base wall than the polygon mirror.

[0012] By having the first light-shielding wall protrude in the first direction to a position closer to the frame base wall than the polygon mirror, the first stray light can be prevented from passing between the first light-shielding wall and the frame base wall and reaching the second scanning lens.

[0013] The scanning optical device may include an optical sensor for detecting the first beam deflected by the deflector and passing through the first scanning lens. The first light-shielding wall blocks first stray light generated when the first beam deflected by the deflector toward the optical sensor is reflected by the incident surface of the first scanning lens, from reaching the second scanning lens.

[0014] The first light-shielding wall can block first stray light generated when the first beam deflected by the deflector toward the optical sensor is reflected by the incident surface of the first scanning lens from reaching the second scanning lens.

[0015] The deflector may include a motor and a circuit board. The motor rotates the polygon mirror. The motor is mounted on the circuit board. The first light-shielding wall may overlap the circuit board when viewed from the first direction.

[0016] The first light-shielding wall overlaps with the circuit board when viewed from the first direction, so that the first light-shielding wall can be disposed close to the polygon mirror, thereby preventing the first stray light from passing between the first light-shielding wall and the polygon mirror and reaching the second scanning lens.

[0017] The frame may have a first wall and a second wall. The first wall extends from the frame base wall toward the cover base wall and has a first opening through which the first beam deflected by the deflector passes. The second wall extends from the frame base wall toward the cover base wall and is located on the opposite side of the polygon mirror from the first wall in the second direction. The second wall has a second opening through which the second beam deflected by the deflector passes. A first scan lens may block the first aperture and a second scan lens may block the second aperture.

[0018] The first scanning lens blocks the first opening in the first wall, and the second scanning lens blocks the second opening in the second wall, thereby preventing sound generated by the rotation of the polygon mirror from leaking out from the space between the first and second walls through the first opening or the second opening.

[0019] The cover may have a second light-blocking wall. The second light-shielding wall blocks second stray light generated by the first light source device and the second light source device. The second light-shielding wall protrudes from the cover base wall toward the frame base wall and is positioned between the first light source device, the second light source device, and the first light-shielding wall in a third direction orthogonal to both the first direction and the second direction. The second light-shielding wall may extend in a direction intersecting the first light-shielding wall, and the first light-shielding wall may be connected to the second light-shielding wall.

[0020] The first light-shielding wall is connected to the second light-shielding wall that extends in a direction intersecting the first light-shielding wall, so that the first light-shielding wall and the second light-shielding wall can reinforce each other, thereby further suppressing deformation of the first light-shielding wall and also suppressing deformation of the second light-shielding wall.

[0021] The first light-shielding wall may extend in a third direction, and the second light-shielding wall may extend in the second direction.

[0022] The first light-shielding wall extends in the third direction, and the second light-shielding wall extends in the second direction, so that the first light-shielding wall and the second light-shielding wall can be effectively reinforced.

[0023] The image forming apparatus includes a main body housing, a process unit, and the above-described scanning optical device. The process unit is located within the main body housing and forms a toner image on a sheet. The process unit has a first photoconductor having a first surface to be scanned and a second photoconductor having a second surface to be scanned. The scanning optical device is located within the main body housing. The cover base wall is closer to the process unit in the first direction than the frame base wall.

[0024] Since sound generated by the rotation of the polygon mirror is likely to leak from the cover base wall side, the cover base wall is closer to the process unit than the frame base wall in the first direction, thereby preventing sound from leaking outside the main body housing.

[0025] The image forming device may include a plate. The plate is located in the main body housing between the cover base wall and the process unit, and has a first plate opening through which the first beam passes and a second plate opening through which the second beam passes.

[0026] The plate is positioned between the cover base wall and the process unit inside the main body housing, and the plate can prevent sound generated by the rotation of the polygon mirror from leaking to the process unit side. [Effects of the Invention]

[0027] Deformation of the light-shielding wall can be suppressed. [Brief explanation of the drawings]

[0028] [Figure 1]FIG. 1 is a diagram illustrating an image forming apparatus. [Figure 2] FIG. 2 is a perspective view showing a scanning optical device. [Figure 3] XX cross-sectional view of FIG. 2. [Figure 4] FIG. 3 is a cross-sectional view of FIG. 2 taken along the line Y-Y. [Figure 5] FIG. [Figure 6] 2 is a cross-sectional view of the scanning optical device as seen from one side in a first direction. FIG. [Figure 7] FIG. [Figure 8] 4 is an enlarged cross-sectional view showing the structure around the first light-shielding wall in FIG. 3. FIG. [Figure 9] FIG. 7 is an enlarged cross-sectional view showing the structure around the first light-shielding wall in FIG. 6. DETAILED DESCRIPTION OF THE INVENTION

[0029] Next, an embodiment will be described. 1, the image forming apparatus 1 is an electrophotographic image forming apparatus. In this embodiment, the image forming apparatus 1 is a color laser printer. The image forming apparatus 1 includes a main body housing 2, a sheet supply unit 3, a scanning optical device 4, a process unit PU, a fixing device 8, and a sheet discharge unit 9.

[0030] The main body housing 2 has a front cover 2A and a discharge tray 2B. The front cover 2A opens and closes the opening on the front side of the main body housing 2.

[0031] The sheet supply unit 3 is located at the bottom inside the main body housing 2. The sheet supply unit 3 includes a sheet tray 3A and a sheet supply mechanism 3B. The sheet tray 3A stores sheets S such as paper. The sheet supply mechanism 3B supplies the sheets S in the sheet tray 3A between the photosensitive drum 5A and the transfer belt 7C.

[0032] The optical scanning device 4 is located in the upper part of the main body housing 2. The optical scanning device 4 emits a beam shown by an imaginary line to expose the surface of the photosensitive drum 5A.

[0033] The image forming apparatus 1 further includes a plate 300. The plate 300 is made of a metal plate. The plate 300 is located inside the main body housing 2, between the scanning optical device 4 and the process unit PU. The plate 300 is fixed to the main body housing 2. The scanning optical device 4 is attached to the plate 300.

[0034] The process unit PU is located inside the main body housing 2, between the sheet tray 3A and the scanning optical device 4. The process unit PU forms a toner image on the sheet S. The process unit PU includes a drum unit 5, four developing cartridges 6, and a transfer unit 7.

[0035] The drum unit 5 can be attached to and detached from the main body housing 2 through an opening in the main body housing 2 that is opened by opening the front cover 2A. The drum unit 5 has four photosensitive drums 5A, four chargers 5B, and a drum frame 5C. The drum frame 5C supports the photosensitive drums 5A and the chargers 5B.

[0036] In this embodiment, the photosensitive drums 5A include a photosensitive drum 5AY on which a yellow toner image is formed, a photosensitive drum 5AM on which a magenta toner image is formed, a photosensitive drum 5AC on which a cyan toner image is formed, and a photosensitive drum 5AK on which a black toner image is formed. The four photosensitive drums 5A are arranged from front to back, in other words, from upstream to downstream in the conveyance direction of the sheet S, in the order of photosensitive drum 5AY, photosensitive drum 5AM, photosensitive drum 5AC, and photosensitive drum 5AK.

[0037] The developing cartridges 6 are detachably attached to the drum frame 5C of the drum unit 5. Each developing cartridge 6 includes a developing roller 6A, a supply roller 6B, a layer thickness regulating blade 6D, a toner containing section 6E that contains toner, and an agitator 6F.

[0038] The agitator 6F agitates the toner in the toner storage unit 6E. The agitator 6F also supplies the toner in the toner storage unit 6E to the supply roller 6B. The supply roller 6B supplies the toner to the developing roller 6A. The layer thickness regulating blade 6D regulates the thickness of the toner on the developing roller 6A to a constant thickness.

[0039] The developer cartridges 6 contain toners of different colors. In this embodiment, the developer cartridges 6 include a developer cartridge 6Y containing yellow toner, a developer cartridge 6M containing magenta toner, a developer cartridge 6C containing cyan toner, and a developer cartridge 6K containing black toner.

[0040] The transfer unit 7 is located between the sheet tray 3A and the drum unit 5. The transfer unit 7 includes a drive roller 7A, a driven roller 7B, a transfer belt 7C, and four transfer rollers 7D. The transfer belt 7C is an endless belt. The drive roller 7A and the driven roller 7B rotate the transfer belt 7C. The transfer roller 7D is located inside the transfer belt 7C. The transfer roller 7D sandwiches the transfer belt 7C between itself and the photosensitive drum 5A.

[0041] The fixing device 8 is located behind the drum unit 5. The fixing device 8 includes a heating roller 8A and a pressure roller 8B. The heating roller 8A heats the sheet S. The pressure roller 8B sandwiches the sheet S between itself and the heating roller 8A.

[0042] The charger 5B charges the surface of the photosensitive drum 5A. The scanning optical device 4 emits a beam to expose the surface of the photosensitive drum 5A. As a result, an electrostatic latent image is formed on the photosensitive drum 5A. The developing roller 6A supplies toner to the photosensitive drum 5A. As a result, a toner image is formed on the photosensitive drum 5A.

[0043] The photosensitive drum 5A on which the toner image has been formed transports the sheet S between itself and the transfer roller 7D. This transfers the toner image onto the sheet S. The heating roller 8A and the pressure roller 8B transport the sheet S on which the toner image has been transferred. This fixes the toner image onto the sheet S.

[0044] The sheet discharge section 9 includes a transport roller 9A and a discharge roller 9B. The transport roller 9A transports the sheet S on which the toner image has been fixed toward the discharge roller 9B. The discharge roller 9B discharges the sheet S onto the discharge tray 2B.

[0045] 2, the scanning optical device 4 includes a housing H, an incident optical system Li, a deflector 50, and scanning optical systems Lo1 and Lo2. In this embodiment, the scanning optical system Lo1 corresponds to the "first scanning optical system," and the scanning optical system Lo2 corresponds to the "second scanning optical system." In the drawings referred to herein, the first, second, and third directions are indicated by arrows on one side and by no arrow on the other side.

[0046] The first direction is the direction in which the rotation axis X1 of the polygon mirror 51 of the deflector 50 extends. The second direction is a direction perpendicular to the first direction. The third direction is a direction perpendicular to both the first direction and the second direction. In this embodiment, the third direction corresponds to the main scanning direction.

[0047] As shown in FIG. 3, the housing H includes a frame 100 and a cover 200. The frame 100 has a frame base wall 110 on the other side in the first direction. The frame base wall 110 is a wall on which the deflector 50 is installed.

[0048] The cover 200 has a cover base wall 210 on one side in the first direction. The cover base wall 210 is a wall that covers the deflector 50 from the side opposite to the frame base wall 110 in the first direction. In other words, the cover base wall 210 covers the deflector 50 from one side in the first direction.

[0049] In this embodiment, the scanning optical device 4 is disposed in the main body housing 2 of the image forming apparatus 1 (see FIG. 1 ) such that the frame base wall 110 is located above the deflector 50 and the cover base wall 210 is located below the deflector 50. That is, in this embodiment, the first direction corresponds to the up-down direction of the image forming apparatus 1. Furthermore, one side of the first direction corresponds to the bottom side of the image forming apparatus 1, and the other side of the first direction corresponds to the top side of the image forming apparatus 1.

[0050] The cover 200 is made of a resin that is softer than the frame 100. In this embodiment, the frame 100 is made of resin, and the cover 200 is made of a resin that is softer than the resin that constitutes the frame 100. Specifically, the frame 100 is made of a resin to which a filler is added to increase strength, and the cover 200 is made of a resin to which no filler is added. As an example, the frame 100 is made of glass fiber reinforced polycarbonate, and the cover 200 is made of polystyrene. The wall thickness of the cover 200 is smaller than the wall thickness of the frame 100.

[0051] The incident optical system Li includes light source devices LM1 and LM2, an aperture wall 30, and a condenser lens 40. In this embodiment, the light source device LM1 corresponds to the "first light source device," and the light source device LM2 corresponds to the "second light source device."

[0052] Light source devices LM1 and LM2 are devices that emit beams BY, BM, BC, and BK. Specifically, light source device LM1 emits beams BY and BM. Light source device LM2 emits beams BC and BK. In this embodiment, beam BY corresponds to the "first beam," and beam BK corresponds to the "second beam."

[0053] 2, the light source devices LM1 and LM2 are aligned in the second direction. The light source device LM1 is located on one side of the light source device LM2 in the second direction.

[0054] Each of the light source devices LM1 and LM2 includes two light sources 10 and two coupling lenses 20. The light sources 10 include a light source 10Y, a light source 10M, a light source 10C, and a light source 10K. The coupling lenses 20 include a coupling lens 20Y, a coupling lens 20M, a coupling lens 20C, and a coupling lens 20K.

[0055] The light source device LM1 includes a light source 10Y, a light source 10M, a coupling lens 20Y, and a coupling lens 20M. The light source device LM2 includes a light source 10C, a light source 10K, a coupling lens 20C, and a coupling lens 20K.

[0056] In this embodiment, the light source 10 is a semiconductor laser and emits laser light. The light source 10Y emits laser light that exposes the yellow photosensitive drum 5AY. The light source 10M emits laser light that exposes the magenta photosensitive drum 5AM. The light source 10C emits laser light that exposes the cyan photosensitive drum 5AC. The light source 10K emits laser light that exposes the black photosensitive drum 5AK.

[0057] Light source 10Y and light source 10M are aligned in a first direction. Light source 10M is located on the other side of light source 10Y in the first direction. Light source 10C and light source 10K are aligned in the first direction. Light source 10C is located on the other side of light source 10K in the first direction.

[0058] Light source 10Y and light source 10K are aligned in the second direction. Light source 10K is located on the other side of light source 10Y in the second direction. Light source 10M and light source 10C are aligned in the second direction. Light source 10C is located on the other side of light source 10M in the second direction.

[0059] The coupling lens 20Y converts the light emitted from the light source 10Y into a beam BY. The coupling lens 20M converts the light emitted from the light source 10M into a beam BM. The coupling lens 20C converts the light emitted from the light source 10C into a beam BC. The coupling lens 20K converts the light emitted from the light source 10K into a beam BK.

[0060] The coupling lens 20Y and the coupling lens 20M are aligned in the first direction. The coupling lens 20M is located on the other side of the coupling lens 20Y in the first direction. In other words, the coupling lens 20M is farther from the cover base wall 210 than the coupling lens 20Y in the first direction.

[0061] The coupling lens 20C and the coupling lens 20K are aligned in the first direction. The coupling lens 20C is located on the other side of the coupling lens 20K in the first direction. In other words, the coupling lens 20C is farther from the cover base wall 210 than the coupling lens 20K in the first direction.

[0062] The coupling lens 20Y and the coupling lens 20K are aligned in the second direction. The coupling lens 20K is located on the other side of the coupling lens 20Y in the second direction. The coupling lens 20M and the coupling lens 20C are aligned in the second direction. The coupling lens 20C is located on the other side of the coupling lens 20M in the second direction.

[0063] 3, the condenser lens 40 is a lens that refracts the beams BY, BM, BC, and BK from the coupling lens 20 in the sub-scanning direction and condenses them on the mirror surface of the polygon mirror 51. In the incident optical system Li, the sub-scanning direction corresponds to the first direction.

[0064] In this embodiment, the condenser lens 40 is a cylindrical lens having a cylindrical entrance surface and a flat exit surface. The condenser lens 40 refracts the beams BY and BK in the first direction so that they approach the frame base wall 110 and focus them on the mirror surface of the polygon mirror 51. The condenser lens 40 also refracts the beams BM and BC in the first direction so that they approach the cover base wall 210 and focus them on the mirror surface of the polygon mirror 51.

[0065] The throttling wall 30 includes a first throttling wall 30A and a second throttling wall 30B. In this embodiment, the first throttling wall 30A and the second throttling wall 30B are integrally formed with the frame 100. That is, the frame 100 has the first throttling wall 30A and the second throttling wall 30B.

[0066] The first diaphragm wall 30A is a wall located between the coupling lenses 20Y, 20M, 20C, and 20K and the condenser lens 40. The first diaphragm wall 30A has openings 31 (see FIG. 2). The openings 31 include an opening 31Y through which the beam BY traveling from the coupling lens 20Y to the polygon mirror 51 passes, an opening 31M through which the beam BM traveling from the coupling lens 20M to the polygon mirror 51 passes, an opening 31C through which the beam BC traveling from the coupling lens 20C to the polygon mirror 51 passes, and an opening 31K through which the beam BK traveling from the coupling lens 20K to the polygon mirror 51 passes.

[0067] The second aperture wall 30B is a wall located between the condenser lens 40 and the deflector 50. The condenser lens 40 is located between the first aperture wall 30A and the second aperture wall 30B. The second aperture wall 30B has two openings 32A and 32B (see also FIG. 6). The opening 32A is an opening through which the beams BY and BM traveling from the coupling lenses 20Y and 20M toward the polygon mirror 51 pass. The opening 32B is an opening through which the beams BC and BK traveling from the coupling lenses 20C and 20K toward the polygon mirror 51 pass.

[0068] The deflector 50 is a device that deflects the beams BY, BM, BC, and BK in the main scanning direction (third direction) and includes a polygon mirror 51, a motor 52, a circuit board 53, a first capacitor 54, and a second capacitor 55.

[0069] The polygon mirror 51 is rotatable about a rotation axis X1 extending in the first direction. The polygon mirror 51 has five mirror surfaces that are equidistant from the rotation axis X1 (see also FIG. 2). The polygon mirror 51 deflects the beams BY, BM, BC, and BK in the main scanning direction by rotating.

[0070] The motor 52 rotates the polygon mirror 51. The motor 52 is fixed to the frame 100 via a circuit board 53. The first capacitor 54 and the second capacitor 55 are cylindrical electronic components that constitute part of the drive circuit of the motor 52.

[0071] The motor 52, the first capacitor 54, and the second capacitor 55 are mounted on the circuit board 53. The motor 52, the first capacitor 54, and the second capacitor 55 are mounted on the circuit board 53 so as to protrude toward the cover base wall 210.

[0072] 4, the scanning optical systems Lo1 and Lo2 are optical systems that form images of the beams BY, BM, BC, and BK deflected by the deflector 50 on the surface of the photosensitive drum 5A. In this embodiment, the surface of the photosensitive drum 5AY corresponds to the "first scanned surface," and the surface of the photosensitive drum 5AK corresponds to the "second scanned surface." Furthermore, the photosensitive drum 5AY corresponds to the "first photosensitive body having the first scanned surface," and the photosensitive drum 5AK corresponds to the "second photosensitive body having the second scanned surface."

[0073] The scanning optical system Lo1 forms an image of the beam BY deflected by the deflector 50 on the surface of the photosensitive drum 5AY. The scanning optical system Lo1 also forms an image of the beam BM deflected by the deflector 50 on the surface of the photosensitive drum 5AM.

[0074] The scanning optical system Lo2 forms an image of the beam BC deflected by the deflector 50 on the surface of the photosensitive drum 5AC. The scanning optical system Lo2 also forms an image of the beam BK deflected by the deflector 50 on the surface of the photosensitive drum 5AK.

[0075] The scanning optical system Lo1 is located on one side of the polygon mirror 51 in the second direction. The scanning optical system Lo2 is located on the other side of the polygon mirror 51 in the second direction. The polygon mirror 51 is located between the scanning optical systems Lo1 and Lo2 in the second direction.

[0076] The scanning optical system Lo1 has scanning lenses 60YM, 70Y, 70M, reflecting mirrors 81Y, 81M, and a mirror 82M. The scanning optical system Lo2 has scanning lenses 60CK, 70C, 70K, reflecting mirrors 81C, 82C, and a reflecting mirror 81K. The components constituting the scanning optical systems Lo1 and Lo2 are fixed to a frame 100.

[0077] The scanning lens 60YM is a lens onto which the beams BY and BM deflected by the deflector 50 are incident, and the scanning lens 60CK is a lens onto which the beams BC and BK deflected by the deflector 50 are incident. In this embodiment, the scanning lens 60YM corresponds to the "first scanning lens," and the scanning lens 60CK corresponds to the "second scanning lens."

[0078] The scanning lenses 60YM and 60CK refract the beams BY, BM, BC, and BK deflected by the deflector 50 in the main scanning direction to form an image on the surface of the photosensitive drum 5A. The scanning lenses 60YM and 60CK have fθ characteristics such that the beams BY, BM, BC, and BK deflected at a constant angular velocity by the deflector 50 scan the surface of the photosensitive drum 5A at a constant velocity. The incident surfaces 61 (see FIG. 9) of the scanning lenses 60YM and 60CK are concave with respect to the deflector 50 and are axisymmetric aspherical surfaces that are axially symmetric with respect to the optical axes of the scanning lenses 60YM and 60CK.

[0079] The scanning lens 60CK is located on the opposite side of the polygon mirror 51 from the scanning lens 60YM in the second direction. Specifically, in the second direction, the scanning lens 60YM is located on one side of the polygon mirror 51, and the scanning lens 60CK is located on the other side of the polygon mirror 51. The scanning lenses 60YM and 60CK are arranged symmetrically with respect to a plane that passes through the rotation axis X1 of the polygon mirror 51 and is perpendicular to the second direction. The polygon mirror 51 is located between the scanning lens 60YM and the scanning lens 60CK in the second direction.

[0080] The reflecting mirror 81Y is a mirror that reflects the beam BY that has passed through the scanning lens 60YM toward the surface of the photosensitive drum 5AY.

[0081] The scanning lens 70Y is a lens that focuses the beam BY reflected by the reflecting mirror 81Y on the surface of the photosensitive drum 5AY. The scanning lenses 70Y, 70M, 70C, and 70K refract the beams BY, BM, BC, and BK in the sub-scanning direction to focus the beams on the surface of the photosensitive drum 5A. In the scanning optical systems Lo1 and Lo2, the sub-scanning direction corresponds to a direction that is perpendicular to both the main scanning direction and the beam traveling direction.

[0082] The mirror 82M is a mirror that reflects the beam BM that has passed through the scanning lens 60YM toward the reflecting mirror 81M. The reflecting mirror 81M is a mirror that reflects the beam BM toward the surface of the photosensitive drum 5AM. The scanning lens 70M is a lens that forms an image of the beam BM reflected by the reflecting mirror 81M on the surface of the photosensitive drum 5AM.

[0083] The mirror 82C is a mirror that reflects the beam BC that has passed through the scanning lens 60CK toward the reflecting mirror 81C. The reflecting mirror 81C is a mirror that reflects the beam BC toward the surface of the photosensitive drum 5AC. The scanning lens 70C is a lens that forms an image of the beam BC reflected by the reflecting mirror 81C on the surface of the photosensitive drum 5AC.

[0084] The reflecting mirror 81K is a mirror that reflects the beam BK that has passed through the scanning lens 60CK toward the surface of the photosensitive drum 5AK. The scanning lens 70K is a lens that forms an image of the beam BK reflected by the reflecting mirror 81K on the surface of the photosensitive drum 5AK.

[0085] 3, the light beams emitted from the light sources 10Y, 10M, 10C, and 10K are converted into beams BY, BM, BC, and BK by passing through the corresponding coupling lenses 20Y, 20M, 20C, and 20K. The beams BY, BM, BC, and BK pass through the corresponding openings 31Y, 31M, 31C, and 31K in the first diaphragm wall 30A and then enter the condenser lens 40. The beams BY, BM, BC, and BK that have passed through the condenser lens 40 pass through the corresponding openings 32A and 32B in the second diaphragm wall 30B and then enter the polygon mirror 51.

[0086] 4, the polygon mirror 51 deflects the beams BY, BM, BC, and BK toward the corresponding scanning optical systems Lo1 and Lo2. The beam BY deflected toward the scanning optical system Lo1 passes through a scanning lens 60YM, is reflected by a reflecting mirror 81Y, passes through a scanning lens 70Y, and is emitted toward the photosensitive drum 5AY. The beam BY forms an image on the surface of the photosensitive drum 5AY and is scanned in the main scanning direction.

[0087] The beam BM deflected toward the scanning optical system Lo1 passes through the scanning lens 60YM, is reflected by the mirror 82M and the reflecting mirror 81M, passes through the scanning lens 70M, and is emitted toward the photosensitive drum 5AM. The beam BM forms an image on the surface of the photosensitive drum 5AM and is scanned in the main scanning direction.

[0088] The beam BC deflected toward the scanning optical system Lo2 passes through the scanning lens 60CK, is reflected by the mirror 82C and the reflecting mirror 81C, passes through the scanning lens 70C, and is emitted toward the photosensitive drum 5AC. The beam BC forms an image on the surface of the photosensitive drum 5AC and is scanned in the main scanning direction.

[0089] The beam BK deflected toward the scanning optical system Lo2 passes through the scanning lens 60CK, is reflected by the reflecting mirror 81K, passes through the scanning lens 70K, and is emitted toward the photosensitive drum 5AK. The beam BK forms an image on the surface of the photosensitive drum 5AK and is scanned in the main scanning direction.

[0090] The plate 300 has a plate base wall 310 and a plate side wall 320 . The plate side wall 320 is a wall fixed to the main body housing 2 of the image forming apparatus 1 (see FIG. 1).

[0091] The plate base wall 310 is a wall on which the scanning optical device 4 is attached. The plate base wall 310 has four plate openings 311. The plate openings 311 are through holes that are long in the main scanning direction and are aligned in the second direction. The plate openings 311 include plate opening 311Y, plate opening 311M, plate opening 311C, and plate opening 311K.

[0092] The plate opening 311Y is an opening through which the beam BY emitted from the scanning optical device 4 toward the photosensitive drum 5AY passes. The plate opening 311M is an opening through which the beam BM emitted from the scanning optical device 4 toward the photosensitive drum 5AM passes. The plate opening 311C is an opening through which the beam BC emitted from the scanning optical device 4 toward the photosensitive drum 5AC passes. The plate opening 311K is an opening through which the beam BK emitted from the scanning optical device 4 toward the photosensitive drum 5AK passes. In this embodiment, the plate opening 311Y corresponds to the "first plate opening", and the plate opening 311K corresponds to the "second plate opening".

[0093] The cover base wall 210 is located below the frame base wall 110. Furthermore, the process unit PU is located below the scanning optical device 4. Therefore, the cover base wall 210 is closer to the process unit PU in the up-down direction than the frame base wall 110. In other words, the cover base wall 210 is closer to the process unit PU in the first direction than the frame base wall 110.

[0094] The plate 300 is located between the cover base wall 210 and the process unit PU inside the main body housing 2. More specifically, the plate base wall 310 is located between the cover base wall 210 and the process unit PU in the first direction. As a result, the plate 300 is arranged to cover the scanning optical device 4 when viewed from the process unit PU side in the first direction.

[0095] 5, the frame 100 has a first wall 120, a second wall 130, and a third wall 140. The first wall 120, the second wall 130, and the third wall 140 are walls extending in one direction from the frame base wall 110. In other words, the first wall 120, the second wall 130, and the third wall 140 are walls extending from the frame base wall 110 toward the cover base wall 210 of the cover 200 (see FIG. 4).

[0096] The first wall 120 extends in the third direction. The other end of the first wall 120 in the third direction is connected to one end of the second diaphragm wall 30B in the second direction. The first wall 120 has a first opening 121. The first opening 121 is an opening through which the beams BY and BM deflected by the deflector 50 pass. The first opening 121 penetrates in the second direction and opens toward one side in the first direction.

[0097] The second wall 130 is located on the opposite side of the polygon mirror 51 from the first wall 120 in the second direction. The second wall 130 extends in the third direction. The other end of the second wall 130 in the third direction is connected to the other end of the second diaphragm wall 30B in the second direction. The second wall 130 has a second opening 131. The second opening 131 is an opening through which the beams BC and BK deflected by the deflector 50 pass. The first opening 121 penetrates in the second direction and opens toward one side in the first direction.

[0098] The third wall 140 is located on the opposite side of the polygon mirror 51 from the second diaphragm wall 30B in the third direction. The third wall 140 extends in the second direction. One end of the third wall 140 in the second direction is connected to one end of the first wall 120 in the third direction, and the other end of the third wall 140 in the second direction is connected to one end of the second wall 130 in the third direction.

[0099] 6, the deflector 50 is disposed in a space 100A surrounded by the first wall 120, the second wall 130, the third wall 140, and the second aperture wall 30B of the frame 100. The scanning lens 60YM is disposed so as to block the first opening 121 of the first wall 120. The scanning lens 60CK is disposed so as to block the second opening 131 of the second wall 130. The condenser lens 40 is disposed so as to block the openings 32A and 32B of the second aperture wall 30B. This configuration can improve the airtightness of the space 100A in which the deflector 50 is disposed.

[0100] The scanning optical device 4 further includes an optical sensor 90 and a mirror 85. The polygon mirror 51 of the deflector 50 rotates counterclockwise in FIG. The optical sensor 90 includes an optical sensor 90Y and an optical sensor 90K.

[0101] The optical sensor 90Y is a sensor for detecting the beam BY1 (BY) that has been deflected by the deflector 50 and passed through the scanning lens 60YM. The beam BY1 is a beam that has passed through the scanning lens 60YM and is located downstream in the main scanning direction from the scanning range that exposes the photosensitive drum 5AY.

[0102] The optical sensor 90K is a sensor for detecting the beam BK1 (BK) that has been deflected by the deflector 50 and passed through the scanning lens 60CK. The beam BK1 is a beam that has passed through the scanning lens 60CK and is located upstream in the main scanning direction from the scanning range that exposes the photosensitive drum 5AK.

[0103] The mirrors 85 include a mirror 85Y and a mirror 85K. The mirror 85Y is a mirror that reflects the beam BY1 toward the optical sensor 90Y. The mirror 85K is a mirror that reflects the beam BK1 toward the optical sensor 90K.

[0104] 7, the cover 200 has a first light-shielding wall 220, a reinforcing wall 230, a rib 240, and a second light-shielding wall 250. The first light-shielding wall 220, the reinforcing wall 230, the rib 240, and the second light-shielding wall 250 protrude from the cover base wall 210 toward the other side of the first direction. In other words, the first light-shielding wall 220, the reinforcing wall 230, the rib 240, and the second light-shielding wall 250 protrude from the cover base wall 210 toward the frame base wall 110 of the frame 100 (see FIG. 8).

[0105] The first light-shielding wall 220 extends in the third direction. Specifically, the first light-shielding wall 220 extends from near the center of the cover base wall 210 in the second and third directions toward the other side of the third direction. The first light-shielding wall 220 has a light-shielding portion 221 and an extending portion 222. The light-shielding portion 221 protrudes further toward the other side in the first direction than the extending portion 222.

[0106] The reinforcing wall 230 extends in a direction intersecting the first light-shielding wall 220. In this embodiment, the reinforcing wall 230 extends in a direction perpendicular to the first light-shielding wall 220. Specifically, the reinforcing wall 230 extends in the second direction. An end of the reinforcing wall 230 that is closer to the first light-shielding wall 220 in the second direction is connected to the first light-shielding wall 220.

[0107] The reinforcing wall 230 includes two first reinforcing walls 231 and two second reinforcing walls 232 . The first reinforcing wall 231 is provided so as to protrude in the second direction from the first light-shielding wall 220. The dimension of the first reinforcing wall 231 in the first direction decreases with increasing distance from the first light-shielding wall 220. In other words, the other end face of the first reinforcing wall 231 in the first direction is inclined so as to approach the cover base wall 210 with increasing distance from the first light-shielding wall 220.

[0108] The second reinforcing wall 232 is located on the other side in the third direction of the first reinforcing wall 231. The second reinforcing wall 232 is provided to extend in the second direction from the first light-shielding wall 220. The second reinforcing wall 232 has an end farther from the first light-shielding wall 220 in the second direction connected to the rib 240.

[0109] The ribs 240 are located on both sides of the first light-shielding wall 220 in the second direction. The ribs 240 extend in the third direction. The second reinforcing walls 232 extend in the second direction and are provided to connect the first light-shielding wall 220 and the ribs 240.

[0110] The second light-shielding wall 250 is located on the other side in the third direction of the first light-shielding wall 220. The second light-shielding wall 250 extends in a direction intersecting the first light-shielding wall 220. In this embodiment, the second light-shielding wall 250 extends in a direction perpendicular to the first light-shielding wall 220. Specifically, the second light-shielding wall 250 extends in the second direction.

[0111] The first light-shielding wall 220 is connected to the second light-shielding wall 250. More specifically, the other end in the third direction of the first light-shielding wall 220 is connected to the second light-shielding wall 250. Furthermore, the other end in the third direction of the extending portion 222 of the first light-shielding wall 220 is connected to the second light-shielding wall 250. The extending portion 222 is provided to connect the light-shielding portion 221 of the first light-shielding wall 220 and the second light-shielding wall 250.

[0112] 8, the first light-shielding wall 220 protrudes in the first direction to a position closer to the frame base wall 110 than the polygon mirror 51. More specifically, the first light-shielding wall 220 has a light-shielding portion 221 protruded in the first direction to a position closer to the frame base wall 110 than the polygon mirror 51. The extension portion 222 is closer to the cover base wall 210 in the first direction than the polygon mirror 51.

[0113] The first capacitor 54 is located between the circuit board 53 and the extending portion 222 of the first light-shielding wall 220 in the first direction. The first capacitor 54 faces the extending portion 222 in the first direction. The dimension of the extending portion 222 in the first direction is set so as not to interfere with the first capacitor 54.

[0114] Similar to the first light-shielding wall 220, the second light-shielding wall 250 protrudes to a position closer to the frame base wall 110 than the polygon mirror 51 in the first direction. The second light-shielding wall 250 is located between the light source devices LM1, LM2 and the first light-shielding wall 220 in the third direction. More specifically, the second light-shielding wall 250 is located between the diaphragm wall 30B and the first light-shielding wall 220 in the third direction. More specifically, the second light-shielding wall 250 is located between the second diaphragm wall 30B and the first light-shielding wall 220 in the third direction.

[0115] As shown in FIG. 9, the first light-shielding wall 220 and the second light-shielding wall 250 are located in the second direction between the optical axis of the coupling lens 20Y (see the imaginary line passing through the center of the coupling lens 20Y) and the optical axis of the coupling lens 20K (see the imaginary line passing through the center of the coupling lens 20K).

[0116] The first light-shielding wall 220 overlaps with the circuit board 53 of the deflector 50 when viewed from the first direction. The first light-shielding wall 220 faces the circuit board 53 in the first direction. Furthermore, at least a portion of the first light-shielding wall 220 is located between the scanning lens 60YM and the scanning lens 60CK when viewed from the first direction. Specifically, the first light-shielding wall 220 has a light-shielding portion 221 located between the scanning lens 60YM and the scanning lens 60CK when viewed from the first direction.

[0117] The first light-shielding wall 220 is provided to block stray light BY2 generated when the beam BY1 is reflected by the incident surface 61 of the scanning lens 60YM from reaching the scanning lens 60CK. More specifically, the first light-shielding wall 220 uses the light-shielding portion 221 to block stray light BY2 generated when the beam BY1 deflected by the deflector 50 toward the optical sensor 90Y is reflected by the incident surface 61 of the scanning lens 60YM from reaching the scanning lens 60CK. In this embodiment, the stray light BY2 corresponds to the "first stray light."

[0118] Furthermore, the first light-shielding wall 220 blocks stray light BK2 generated when the beam BK1 is reflected by the incident surface 61 of the scanning lens 60CK from reaching the scanning lens 60YM. More specifically, the first light-shielding wall 220 uses the light-shielding portion 221 to block stray light BK2 generated when the beam BK1 deflected by the deflector 50 toward the optical sensor 90K is reflected by the incident surface 61 of the scanning lens 60CK from reaching the scanning lens 60YM.

[0119] When viewed from the first direction, the reinforcing wall 230 overlaps with the circuit board 53 of the deflector 50. In particular, the first reinforcing wall 231 and the second reinforcing wall 232 overlap with the circuit board 53 when viewed from the first direction. When viewed from the first direction, the second light-shielding wall 250 does not overlap with the circuit board 53. The second light-shielding wall 250 is closer to the light source devices LM1 and LM2 than the circuit board 53 is in the third direction.

[0120] The second light-shielding wall 250 is provided to block stray light LS generated by the light source devices LM1, LM2, etc. In more detail, in the scanning optical device 4, for example, light from the light source 10 may be reflected by the inner surface of the holder that holds the coupling lens 20, the wall of the frame 100, etc., and become stray light LS.

[0121] When the stray light LS is deflected by the deflector 50, passes through the scanning optical systems Lo1 and Lo2, and reaches the surface of the photosensitive drum 5A, it may cause a ghost in the image formed on the sheet S. In this embodiment, the second light-shielding wall 250 can block the stray light LS generated by the light source devices LM1 and LM2, etc. The stray light LS corresponds to the "second stray light."

[0122] Next, the effects of the embodiment will be described. The cover 200 has a reinforcing wall 230 that extends in a direction intersecting the first light-shielding wall 220 and is connected to the first light-shielding wall 220, so that the cover 200, which is made of a resin softer than the frame 100, has the first light-shielding wall 220, and deformation of the first light-shielding wall 220 can be suppressed.

[0123] The reinforcing wall 230 includes the first reinforcing wall 231 whose dimension in the first direction decreases with increasing distance from the first light-shielding wall 220, thereby making it possible to suppress interference between the first reinforcing wall 231 and the beams BY, BM, BC, and BK.

[0124] Since the reinforcing wall 230 includes the second reinforcing wall 232 connected to the rib 240, the second reinforcing wall 232 can be reinforced by the rib 240, and therefore the second reinforcing wall 232 can further suppress deformation of the first light-shielding wall 220.

[0125] The first light-shielding wall 220 protrudes in the first direction to a position closer to the frame base wall 110 than the polygon mirror 51, thereby preventing stray light BY2 from passing between the first light-shielding wall 220 and the frame base wall 110 and reaching the scanning lens 60CK. Also, stray light BK2 can be prevented from passing between the first light-shielding wall 220 and the frame base wall 110 and reaching the scanning lens 60YM.

[0126] The first light-shielding wall 220 can block stray light BY2 generated when the beam BY1 deflected by the deflector 50 toward the optical sensor 90Y is reflected by the incident surface 61 of the scanning lens 60YM, from reaching the scanning lens 60CK. Also, the first light-shielding wall 220 can block stray light BK2 generated when the beam BK1 deflected by the deflector 50 toward the optical sensor 90K is reflected by the incident surface 61 of the scanning lens 60CK, from reaching the scanning lens 60YM.

[0127] When viewed from the first direction, the first light-shielding wall 220 overlaps with the circuit board 53, so that the first light-shielding wall 220 can be disposed close to the polygon mirror 51. This makes it possible to prevent stray light BY2 from passing between the first light-shielding wall 220 and the polygon mirror 51 and reaching the scanning lens 60CK. Also, it is possible to prevent stray light BK2 from passing between the first light-shielding wall 220 and the polygon mirror 51 and reaching the scanning lens 60YM.

[0128] The scanning lens 60YM blocks the first opening 121 of the first wall 120, and the scanning lens 60CK blocks the second opening 131 of the second wall 130, thereby preventing the sound generated by the rotation of the polygon mirror 51 from leaking out from the space 100A between the first wall 120 and the second wall 130 through the first opening 121 or the second opening 131.

[0129] Furthermore, by the condenser lens 40 closing the openings 32A and 32B of the second diaphragm wall 30B, it is possible to prevent the sound generated by the rotation of the polygon mirror 51 from leaking from the space 100A through the openings 32A and 32B to the outside.

[0130] If the first light-shielding wall 220 is close to the polygon mirror 51, sound is more likely to be generated by the rotation of the polygon mirror 51. In this embodiment, by blocking the openings 32A, 32B, 121, 131 of the walls 30B, 120, 130 with the lenses 40, 60YM, 60CK, it is possible to effectively prevent sound generated by the rotation of the polygon mirror 51 from leaking to the outside.

[0131] The first light-shielding wall 220 is connected to the second light-shielding wall 250 extending in a direction intersecting the first light-shielding wall 220, so that the first light-shielding wall 220 and the second light-shielding wall 250 can reinforce each other. This makes it possible to further suppress deformation of the first light-shielding wall 220 and also suppress deformation of the second light-shielding wall 250.

[0132] The first light-shielding wall 220 extends in the third direction, and the second light-shielding wall 250 extends in the second direction perpendicular to the third direction, so that the first light-shielding wall 220 and the second light-shielding wall 250 can be effectively reinforced.

[0133] Sound generated by the rotation of the polygon mirror 51 tends to leak from the cover base wall 210 side, and therefore, by having the cover base wall 210 closer to the process unit PU in the first direction than the frame base wall 110, it is possible to prevent the sound from leaking outside the main body housing 2. In other words, since the cover base wall 210 is farther from the outer wall of the main body housing 2 in the first direction than the frame base wall 110, it is possible to prevent the sound generated by the rotation of the polygon mirror 51 from leaking outside the main body housing 2.

[0134] The plate 300 is positioned between the cover base wall 210 and the process unit PU inside the main body housing 2, and the plate 300 can prevent the sound generated by the rotation of the polygon mirror 51 from leaking to the process unit PU side.

[0135] Although the embodiments have been described above, the scanning optical device and the image forming device can be modified as appropriate as exemplified below.

[0136] In the above embodiment, the first light-shielding wall 220 was positioned so as to overlap the circuit board 53 of the deflector 50 when viewed from the first direction, but for example, the first light-shielding wall may be positioned so as not to overlap the circuit board when viewed from the first direction.

[0137] In the above embodiment, the first shading wall 220 protruded to a position closer to the frame base wall 110 in the first direction than the polygon mirror 51, but for example, the first shading wall may not protrude to a position closer to the frame base wall in the first direction than the polygon mirror.

[0138] In the above embodiment, at least a portion (mainly the light-shielding portion 221) of the first light-shielding wall 220 is located between the scanning lens 60YM and the scanning lens 60CK when viewed from the first direction, but, for example, the entire first light-shielding wall may be located between the first scanning lens and the second scanning lens when viewed from the first direction.

[0139] In the above embodiment, the first light-shielding wall 220 is connected to the second light-shielding wall 250, but for example, the first light-shielding wall does not have to be connected to the second light-shielding wall.

[0140] In the above embodiment, the dimension of the first reinforcing wall 231 in the first direction decreases with increasing distance from the first light-shielding wall 220, but for example, the reinforcing wall may have a shape in which the dimension in the first direction does not change. In the above embodiment, the second reinforcing wall 232 is connected to the rib 240, but for example, the reinforcing wall may not be connected to the rib.

[0141] In the above embodiment, the reinforcing wall 230 extends in a direction perpendicular to the first light-shielding wall 220, but for example, the reinforcing wall may extend obliquely relative to the first light-shielding wall. Also, the number of reinforcing walls is arbitrary.

[0142] In the above embodiment, the second light-shielding wall 250 extends in a direction perpendicular to the first light-shielding wall 220, but for example, the second light-shielding wall may extend obliquely relative to the first light-shielding wall. In the above embodiment, the cover 200 has the second light-shielding wall 250, but for example, the cover may not have the second light-shielding wall.

[0143] In the above embodiment, the cover base wall 210 was positioned closer to the process unit PU in the first direction than the frame base wall 110, but for example, the cover base wall may be positioned farther from the process unit in the first direction than the frame base wall.

[0144] In the above embodiment, the frame 100 has the first wall 120 and the second wall 130, but for example, the frame does not have to have the first wall and the second wall.

[0145] In the above embodiment, the image forming apparatus 1 includes the plate 300, but for example, the image forming apparatus does not need to include a plate. In the above embodiment, the image forming apparatus 1 is a printer, but for example, the image forming apparatus may be a copier, a multifunction peripheral, or the like.

[0146] In the above embodiment, the scanning optical device 4 is a scanning optical device used in the image forming apparatus 1, but for example, the scanning optical device may be a scanning optical device used in a device other than an image forming apparatus.

[0147] The elements described in the above-described embodiment and modified examples may be implemented in any combination. [Explanation of symbols]

[0148] 4. Scanning optical device 5AY Photosensitive drum 5AK Photosensitive drum 50 Deflector 51 Polygon Mirror 60YM Scan Lens 61 Incidence plane 60CK Scan Lens 100 frames 110 Frame base wall 200 covers 210 Cover base wall 220 First Light-Shielding Wall 230 Reinforced Wall BY,BY1 beam BY2 stray light BK Beam LM1 light source device LM2 light source device Lo1 scanning optical system Lo2 scanning optical system X1 rotation axis

Claims

1. a first light source device that emits a first beam; a second light source device that emits a second beam; a deflector for deflecting the first beam and the second beam, the deflector having a polygon mirror rotatable about a rotation axis extending in a first direction; a first scanning optical system that forms an image of the first beam deflected by the deflector on a first scanned surface, the first scanning optical system having a first scanning lens onto which the first beam deflected by the deflector is incident; a second scanning optical system that forms an image of the second beam deflected by the deflector on a second scanned surface, the second scanning optical system being located on the opposite side of the polygon mirror from the first scanning lens in a second direction orthogonal to the first direction, and including a second scanning lens on which the second beam deflected by the deflector is incident; a frame having a frame base wall on which the deflector is installed; a cover having a cover base wall that covers the deflector from the opposite side to the frame base wall in the first direction, the cover being made of a resin that is softer than the frame; The cover is a first light-shielding wall that blocks first stray light generated when the first beam is reflected by the incident surface of the first scanning lens from reaching the second scanning lens, the first light-shielding wall protruding from the cover base wall toward the frame base wall, and at least a portion of the first light-shielding wall being located between the first scanning lens and the second scanning lens when viewed from the first direction; a reinforcing wall protruding from the cover base wall toward the frame base wall, extending in a direction intersecting the first light-shielding wall and connected to the first light-shielding wall.

2. 2. The scanning optical device according to claim 1, wherein the reinforcing walls include a first reinforcing wall whose dimension in the first direction decreases with increasing distance from the first light-shielding wall.

3. the cover has a rib protruding from the cover base wall toward the frame base wall, 2. The scanning optical device according to claim 1, wherein the reinforcing wall includes a second reinforcing wall connected to the rib.

4. 2. The scanning optical device according to claim 1, wherein the first light-shielding wall protrudes to a position closer to the frame base wall than the polygon mirror in the first direction.

5. an optical sensor for detecting the first beam deflected by the deflector and passing through the first scanning lens; 2. The scanning optical device according to claim 1, wherein the first light-shielding wall blocks the first stray light generated when the first beam deflected by the deflector toward the optical sensor is reflected by the incident surface of the first scanning lens from reaching the second scanning lens.

6. The deflector comprises: a motor that rotates the polygon mirror; a circuit board on which the motor is mounted, 2. The scanning optical device according to claim 1, wherein the first light-shielding wall overlaps with the circuit board when viewed from the first direction.

7. The frame is a first wall extending from the frame base wall toward the cover base wall, the first wall having a first opening through which the first beam deflected by the deflector passes; a second wall extending from the frame base wall toward the cover base wall and positioned on the opposite side of the polygon mirror from the first wall in the second direction, the second wall having a second opening through which the second beam deflected by the deflector passes; the first scanning lens covers the first opening; 2. The scanning optical device according to claim 1, wherein the second scanning lens closes the second opening.

8. the cover includes a second light-shielding wall that blocks second stray light generated by the first light source device and the second light source device, the second light-shielding wall protruding from the cover base wall toward the frame base wall and positioned between the first light source device and the second light source device and the first light-shielding wall in a third direction orthogonal to both the first direction and the second direction; the second light-shielding wall extends in a direction intersecting the first light-shielding wall, 2. The scanning optical device according to claim 1, wherein the first light-shielding wall is connected to the second light-shielding wall.

9. the first light-shielding wall extends in the third direction, 9. The scanning optical device according to claim 8, wherein the second light-shielding wall extends in the second direction.

10. A main body housing; a process unit located within the main body housing and configured to form a toner image on a sheet, the process unit including a first photosensitive member having the first scanned surface and a second photosensitive member having the second scanned surface; the scanning optical device according to any one of claims 1 to 9, which is located in the main body housing; The image forming apparatus is characterized in that the cover base wall is closer to the process unit than the frame base wall in the first direction.

11. 11. The image forming apparatus according to claim 10, further comprising a plate located between the cover base wall and the process unit within the main body housing, the plate having a first plate opening through which the first beam passes and a second plate opening through which the second beam passes.

Images