Scanning optical device and image forming apparatus

Abstract

To provide a scanning optical device that can suppress generation of noise along with rotation of a polygon mirror while blocking stray light, and an image forming apparatus.SOLUTION: A scanning optical device 4 comprises: a deflector 50 that has a polygon mirror 51; a scanning optical system that has a scanning lens 60YM; a scanning optical system that has a scanning lens 60CK; a frame 100 that has a frame base wall 110 on which the deflector 50 is installed; and a cover 200 that has a cover base wall 210. The cover 200 has a first light shielding wall 240B that extends from the cover base wall 210 toward the frame base wall 110, is located between the polygon mirror 51 and the scanning lens 60CK, and overlaps the incidence surface 61 of the scanning lens 60CK when seen from a second direction. The frame 100 has a second light shielding wall 120B that extends from the frame base wall 110 toward the cover base wall 210, is located side of the emission surface 62 of the scanning lens 60CK, and overlaps the emission surface 62 when seen from the second direction.SELECTED DRAWING: Figure 13

Description

Technical Field

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

Background Art

[0002] Conventionally, as a scanning optical device, there is known one including a polygon mirror that deflects and scans a beam, a first imaging lens that forms an image of the beam on a drum, and a second imaging lens that forms an image of another beam on another drum (Patent Document 1). The first imaging lens and the second imaging lens face each other with the polygon mirror interposed therebetween.

[0003] In this technology, light shielding walls are provided between the polygon mirror and the scanning lenses, respectively. The light shielding wall has an opening through which the beam deflected by the polygon mirror passes. Further, the light shielding wall has a function of blocking the beam (stray light) reflected by the incident surface of one imaging lens from entering the other imaging lens.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in the conventional configuration, the entire light shielding wall was located in the narrow space between the polygon mirror and the scanning lens. Therefore, the distance from the polygon mirror to the entire light shielding wall became small, and when the polygon mirror rotated, the noise generated by the repeated compression of the air between the mirror surface of the polygon mirror and the light shielding wall tended to increase. Therefore, it is desired to be able to suppress the generation of noise associated with the rotation of the polygon mirror while blocking stray light.

Means for Solving the Problems

[0006] 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. The deflector has a polygon mirror that is rotatable about a rotation axis extending in a first direction. The first scanning optical system forms an image of the first beam deflected by the deflector on a first scanned surface. The first scanning optical system has a first scanning lens into 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 side opposite to the first scanning lens with the polygon mirror interposed therebetween in a second direction orthogonal to the first direction, and has a second scanning lens into which the second beam deflected by the deflector is incident. The frame has a frame base wall on which the deflector is installed. The cover has a cover base wall that covers the deflector from the side opposite to the frame base wall in the first direction. The cover has a first light-shielding wall. The first light-shielding wall extends from the cover base wall toward the frame base wall. The first light-shielding wall is located between the polygon mirror and the first scanning lens. The first light-shielding wall overlaps the incident surface of the first scanning lens when viewed from the second direction. The frame has a second light-shielding wall. The second light-shielding wall extends from the frame base wall toward the cover base wall. The second light-shielding wall is located on the emission surface side of the first scanning lens. The second light-shielding wall overlaps the emission surface of the first scanning lens when viewed from the second direction.

[0007] By having the first light-shielding wall and the second light-shielding wall, it is possible to block the light (stray light) reflected by the second scanning lens by the first light-shielding wall and the second light-shielding wall. Further, since the second light-shielding wall extending from the frame base wall where the deflector is installed is located on the emission surface side of the first scanning lens, the distance from the polygon mirror to the second light-shielding wall can be ensured. Thereby, the generation of noise associated with the rotation of the polygon mirror can be suppressed.

[0008] The end face of the first light-shielding wall close to the frame base wall may be located closer to the cover base wall than the polygon mirror in the first direction. The end face of the second light-shielding wall close to the cover base wall may be located closer to the frame base wall than the polygon mirror in the first direction.

[0009] The first light-shielding wall may have a shape that bends away from the rotation axis of the polygon mirror in the second direction when viewed from the first direction.

[0010] By having the first light-shielding wall with a shape that bends away from the rotation axis of the polygon mirror in the second direction when viewed from the first direction, the distance in the second direction from the polygon mirror to the first light-shielding wall can be ensured. Thereby, the generation of noise associated with the rotation of the polygon mirror can be more effectively suppressed.

[0011] The first light-shielding wall may have a first portion and a second portion. The first portion faces the rotation axis of the polygon mirror in the second direction. The second portion faces the center of the first scanning lens in the third direction orthogonal to both the first direction and the second direction in the second direction. The distance in the second direction from the rotation axis of the polygon mirror to the first portion is greater than the distance in the second direction from the rotation axis of the polygon mirror to the second portion.

[0012] The distance in the second direction from the rotation axis of the polygon mirror to the first part of the first light-shielding wall is greater than the distance in the second direction from the rotation axis of the polygon mirror to the second part, so that the distance in the second direction from the polygon mirror to the first light-shielding wall can be ensured. Thereby, the generation of noise associated with the rotation of the polygon mirror can be further suppressed.

[0013] The first scanning lens may have a convex portion that protrudes toward the polygon mirror from the center in the third direction of the first scanning lens, and the frame may have a concave portion into which the convex portion fits.

[0014] Since the frame has a concave portion into which the convex portion of the first scanning lens fits, the first scanning lens can be positioned with respect to the frame.

[0015] The end face of the first light-shielding wall close to the frame base wall may be inclined so as to approach the cover base wall as it approaches the first scanning lens in the second direction.

[0016] Since the end face of the first light-shielding wall close to the frame base wall is inclined so as to approach the cover base wall as it approaches the first scanning lens in the second direction, it is possible to suppress the light that has traveled from the light source device from being reflected by the end face of the first light-shielding wall.

[0017] The light-emitting surface of the first scanning lens is a convex surface with a shape in which the center in the third direction, which is perpendicular to both the first direction and the second direction, protrudes in the second direction. The second light-shielding wall may have a shape that follows the light-emitting surface of the first scanning lens when viewed from the first direction.

[0018] Since the second light-shielding wall has a shape that follows the light-emitting surface of the first scanning lens when viewed from the first direction, the second shielding wall can be provided compactly along the first scanning lens. Thereby, the scanning optical device can be miniaturized.

[0019] The end face of the second light-shielding wall close to the cover base wall may be inclined so as to approach the frame base wall as it moves away from the first scanning lens in the second direction.

[0020] The end face of the second light-shielding wall close to the cover base wall is inclined so as to approach the frame base wall as it moves away from the first scanning lens in the second direction, thereby suppressing the reflection of the light traveling from the light source device at the end face of the second light-shielding wall.

[0021] The first scanning optical system includes a reflection mirror and a third scanning lens, and the frame may have a third light-shielding wall. The reflection mirror reflects the first beam that has passed through the first scanning lens toward the first scanned surface. The third scanning lens forms an image of the first beam reflected by the reflection mirror on the first scanned surface. The third light-shielding wall extends in a third direction orthogonal to both the first direction and the second direction. The third light-shielding wall is located between the reflection mirror and the third scanning lens. The third light-shielding wall overlaps the incident surface of the third scanning lens when viewed from the first direction.

[0022] By having the third light-shielding wall, stray light that could not be blocked by the first light-shielding wall and the second light-shielding wall can be blocked by the third light-shielding wall.

[0023] The third light-shielding wall may be located on the side opposite to the polygon mirror across the optical axis of the third scanning lens in the second direction.

[0024] Since the third light-shielding wall is located on the side opposite to the polygon mirror across the optical axis of the third scanning lens in the second direction, the third scanning lens can be arranged closer to the first scanning lens. As a result, the scanning optical device can be miniaturized.

[0025] The end face of the third light-shielding wall close to the optical axis of the third scanning lens may be inclined so as to move away from the optical axis of the third scanning lens as it approaches the third scanning lens.

[0026] Since the end face of the third light-shielding wall close to the optical axis of the third scanning lens is inclined so as to move away from the optical axis of the third scanning lens as it approaches the third scanning lens, the reflection of the light traveling from the light source device at the end face of the third light-shielding wall can be suppressed.

[0027] The scanning optical device may include an elastic member. The elastic member is located between the cover and the first scanning lens. The elastic member closes the gap between the first light shielding wall and the first scanning lens.

[0028] By providing the scanning optical device with an elastic member that closes the gap between the first light shielding wall and the first scanning lens, it is possible to suppress dust from entering the scanning optical device through the gap between the cover and the first scanning lens by the elastic member. Further, it is possible to suppress stray light from passing between the first light shielding wall and the first scanning lens by the elastic member.

[0029] The image forming apparatus includes the above-described scanning optical device. The scanning optical device is arranged such that the frame base wall is located above the deflector and the cover base wall is located below the deflector.

Effect of the Invention

[0030] While blocking stray light, it is possible to suppress the generation of noise associated with the rotation of the polygon mirror.

Brief Description of the Drawings

[0031]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Mode for Carrying Out the Invention

[0032] Next, embodiments will be described. As shown in FIG. 1, the image forming apparatus 1 is an electrophotographic image forming apparatus. In the present 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 drum unit 5, four developing cartridges 6, a transfer unit 7, a fixing device 8, and a sheet discharge unit 9.

[0033] 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.

[0034] The sheet supply unit 3 is located in the lower part 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 sheet S in the sheet tray 3A between the photosensitive drum 5A and the transfer belt 7C.

[0035] The scanning optical device 4 is located in the upper part inside the main body housing 2. The scanning optical device 4 emits a beam indicated by a virtual line to expose the surface of the photosensitive drum 5A.

[0036] The drum unit 5 is positioned between the sheet tray 3A and the scanning optical device 4. The drum unit 5 is detachable from the main body housing 2 through an opening of the main body housing 2 that is opened by opening the front cover 2A. The drum unit 5 includes 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.

[0037] 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 in the order of the photosensitive drum 5AY, the photosensitive drum 5AM, the photosensitive drum 5AC, and the photosensitive drum 5AK from the front to the rear, in other words, from the upstream to the downstream in the conveyance direction of the sheet S.

[0038] The developing cartridge 6 is detachable from 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 storage portion 6E for storing toner, and an agitator 6F.

[0039] The agitator 6F stirs the toner in the toner storage portion 6E. Also, the agitator 6F supplies the toner in the toner storage portion 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.

[0040] The developing cartridges 6 store toners of different colors. In this embodiment, the developing cartridges 6 include a developing cartridge 6Y for storing yellow toner, a developing cartridge 6M for storing magenta toner, a developing cartridge 6C for storing cyan toner, and a developing cartridge 6K for storing black toner.

[0041] The transfer unit 7 is positioned 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 rollers 7D are positioned inside the transfer belt 7C. The transfer rollers 7D sandwich the transfer belt 7C between them and the photosensitive drum 5A.

[0042] The fixing device 8 is positioned 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 it and the heating roller 8A.

[0043] 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. Thereby, an electrostatic latent image is formed on the photosensitive drum 5A. The developing roller 6A supplies toner to the photosensitive drum 5A. Thereby, a toner image is formed on the photosensitive drum 5A.

[0044] The photosensitive drum 5A on which the toner image is formed conveys the sheet S between it and the transfer roller 7D. Thereby, the toner image is transferred onto the sheet S. The heating roller 8A and the pressure roller 8B convey the sheet S onto which the toner image has been transferred. Thereby, the toner image is fixed onto the sheet S.

[0045] The sheet discharge unit 9 includes a conveying roller 9A and a discharge roller 9B. The conveying roller 9A conveys the sheet S onto which the toner image has been fixed toward the discharge roller 9B. The discharge roller 9B discharges the sheet S to the discharge tray 2B.

[0046] As shown in FIG. 2, the scanning optical device 4 includes a housing H, an incident optical system Li, a deflector 50, and scanning optical systems Lo1, Lo2. Here, in the drawings for reference, in each of the first direction, the second direction, and the third direction, the side with an arrow indicates one direction, and the side without an arrow indicates the other direction.

[0047] 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 orthogonal to the first direction. The third direction is a direction orthogonal to both the first direction and the second direction. In the present embodiment, the third direction corresponds to the main scanning direction.

[0048] 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 the wall on which the deflector 50 is installed.

[0049] 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.

[0050] In the present embodiment, the scanning optical device 4 is arranged 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 the present embodiment, the first direction corresponds to the vertical direction of the image forming apparatus 1. Further, one side in the first direction corresponds to the lower side of the image forming apparatus 1, and the other side in the first direction corresponds to the upper side of the image forming apparatus 1.

[0051] The incident optical system Li includes light source devices LM1, LM2, a diaphragm wall 30, and a condenser lens 40.

[0052] The light source devices LM1, LM2 are devices that emit beams BY, BM, BC, BK. Specifically, the light source device LM1 emits the beams BY, BM. The light source device LM2 emits the beams BC, BK. As shown in FIG. 2, the light source devices LM1, LM2 are arranged side by side in the second direction. The light source device LM1 is located on one side in the second direction of the light source device LM2.

[0053] The light source devices LM1 and LM2 each include two light sources 10 and two coupling lenses 20. The light source 10 includes a light source 10Y, a light source 10M, a light source 10C, and a light source 10K. The coupling lens 20 includes a coupling lens 20Y, a coupling lens 20M, a coupling lens 20C, and a coupling lens 20K.

[0054] 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.

[0055] In this embodiment, the light source 10 is a semiconductor laser that emits laser light. The light source 10Y emits laser light for exposing the yellow photosensitive drum 5AY. The light source 10M emits laser light for exposing the magenta photosensitive drum 5AM. The light source 10C emits laser light for exposing the cyan photosensitive drum 5AC. The light source 10K emits laser light for exposing the black photosensitive drum 5AK.

[0056] The light source 10Y and the light source 10M are arranged side by side in the first direction. The light source 10M is located on the other side of the light source 10Y in the first direction. The light source 10C and the light source 10K are arranged side by side in the first direction. The light source 10C is located on the other side of the light source 10K in the first direction.

[0057] The light source 10Y and the light source 10K are arranged side by side in the second direction. The light source 10K is located on the other side of the light source 10Y in the second direction. The light source 10M and the light source 10C are arranged side by side in the second direction. The light source 10C is located on the other side of the light source 10M in the second direction.

[0058] 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.

[0059] The coupling lens 20Y and the coupling lens 20M are arranged side by side 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.

[0060] The coupling lens 20C and the coupling lens 20K are arranged side by side 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.

[0061] The coupling lens 20Y and the coupling lens 20K are arranged side by side 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 arranged side by side in the second direction. The coupling lens 20C is located on the other side of the coupling lens 20M in the second direction.

[0062] As shown in FIG. 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.

[0063] In the present embodiment, the condenser lens 40 is a cylindrical lens having a cylindrical incident surface and a flat exit surface. The condenser lens 40 refracts the beams BY and BK so as to approach the frame base wall 110 in the first direction and condenses them on the mirror surface of the polygon mirror 51. Further, the condenser lens 40 refracts the beams BM and BC so as to approach the cover base wall 210 in the first direction and condenses them on the mirror surface of the polygon mirror 51.

[0064] The aperture wall 30 includes a first aperture wall 30A and a second aperture wall 30B. In the present embodiment, the first aperture wall 30A and the second aperture wall 30B are integrally formed with the frame 100. That is, the frame 100 has the first aperture wall 30A and the second aperture wall 30B.

[0065] The first aperture wall 30A is a wall located between the coupling lenses 20Y, 20M, 20C, 20K and the condenser lens 40. The first aperture wall 30A has an opening 31 (see FIG. 2). The opening 31 includes an opening 31Y through which the beam BY traveling from the coupling lens 20Y toward the polygon mirror 51 passes, an opening 31M through which the beam BM traveling from the coupling lens 20M toward the polygon mirror 51 passes, an opening 31C through which the beam BC traveling from the coupling lens 20C toward the polygon mirror 51 passes, and an opening 31K through which the beam BK traveling from the coupling lens 20K toward the polygon mirror 51 passes.

[0066] 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, 32B (see also FIG. 7). The opening 32A is an opening through which the beams BY, BM traveling from the coupling lenses 20Y, 20M toward the polygon mirror 51 pass. The opening 32B is an opening through which the beams BC, BK traveling from the coupling lenses 20C, 20K toward the polygon mirror 51 pass.

[0067] The deflector 50 is a device that deflects the beams BY, BM, BC, BK in the main scanning direction (third direction). The deflector 50 has a polygon mirror 51 and a motor 52. The polygon mirror 51 is rotatable about a rotation axis X1 extending in the first direction. The polygon mirror 51 has five mirror surfaces provided at an equal distance from the rotation axis X1 (see also FIG. 2). The polygon mirror 51 deflects the beams BY, BM, BC, BK in the main scanning direction by rotating. The motor 52 is a motor that rotates the polygon mirror 51. The motor 52 is fixed to the frame 100 via a substrate 53.

[0068] As shown in FIG. 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 as the surface to be scanned.

[0069] 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. Further, the scanning optical system Lo1 forms an image of the beam BM deflected by the deflector 50 on the surface of the photosensitive drum 5AM.

[0070] 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. Further, the scanning optical system Lo2 forms an image of the beam BK deflected by the deflector 50 on the surface of the photosensitive drum 5AK.

[0071] 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 system Lo1 and the scanning optical system Lo2 in the second direction.

[0072] The scanning optical system Lo1 includes a scanning lens 60YM, a scanning lens 70Y, a scanning lens 70M, a reflection mirror 81Y, a reflection mirror 81M, and a mirror 82M. The scanning optical system Lo2 includes a scanning lens 60CK, a scanning lens 70C, a scanning lens 70K, a reflection mirror 81C, a mirror 82C, and a reflection mirror 81K. Each component constituting the scanning optical systems Lo1 and Lo2 is fixed to the frame 100.

[0073] The scanning lens 60YM is a lens into which the beams BY and BM deflected by the deflector 50 are incident, and the scanning lens 60CK is a lens into which the beams BC and BK deflected by the deflector 50 are incident. The scanning lenses 60YM and 60CK refract the beams BY, BM, BC, and BK deflected by the deflector 50 in the main scanning direction and form an image on the surface of the photosensitive drum 5A. Further, the scanning lenses 60YM and 60CK have an fθ characteristic such that the beams BY, BM, BC, and BK deflected at a constant angular velocity by the deflector 50 are scanned at a constant speed on the surface of the photosensitive drum 5A.

[0074] The scanning lens 60YM is located on the opposite side of the scanning lens 60CK across the polygon mirror 51 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 lens 60YM and the scanning lens 60CK are arranged symmetrically with respect to a plane perpendicular to the second direction passing through the rotation axis X1 of the polygon mirror 51. The polygon mirror 51 is located between the scanning lens 60YM and the scanning lens 60CK in the second direction.

[0075] 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.

[0076] The scanning lens 70Y is a lens that forms an image of 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 and form an image on the surface of the photosensitive drum 5A. In the scanning optical systems Lo1 and Lo2, the sub-scanning direction corresponds to a direction perpendicular to both the main scanning direction and the traveling direction of the beam.

[0077] 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 reflection mirror 81M on the surface of the photosensitive drum 5AM.

[0078] The mirror 82C is a mirror that reflects the beam BC that has passed through the scanning lens 60CK toward the reflection mirror 81C. The reflection 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 reflection mirror 81C on the surface of the photosensitive drum 5AC.

[0079] The reflection 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 reflection mirror 81K on the surface of the photosensitive drum 5AK.

[0080] As shown in FIG. 3, the light emitted from each light source 10Y, 10M, 10C, 10K is converted into beams BY, BM, BC, BK by passing through the corresponding coupling lenses 20Y, 20M, 20C, 20K. The beams BY, BM, BC, BK pass through the corresponding apertures 31Y, 31M, 31C, 31K of the first aperture diaphragm 30A and then enter the condenser lens 40. The beams BY, BM, BC, BK that have passed through the condenser lens 40 pass through the corresponding apertures 32A, 32B of the second aperture diaphragm 30B and enter the polygon mirror 51.

[0081] As shown in FIG. 4, the polygon mirror 51 deflects the beams BY, BM, BC, BK toward the corresponding scanning optical systems Lo1, Lo2. The beam BY deflected toward the scanning optical system Lo1 passes through the scanning lens 60YM, is then reflected by the reflection mirror 81Y, and passes through the scanning lens 70Y and is emitted toward the photosensitive drum 5AY. The beam BY is imaged on the surface of the photosensitive drum 5AY and is scanned in the main scanning direction.

[0082] The beam BM deflected toward the scanning optical system Lo1 passes through the scanning lens 60YM, is then 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 is imaged on the surface of the photosensitive drum 5AM and scanned in the main scanning direction.

[0083] The beam BC deflected toward the scanning optical system Lo2 passes through the scanning lens 60CK, is then 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 is imaged on the surface of the photosensitive drum 5AC and scanned in the main scanning direction.

[0084] The beam BK deflected toward the scanning optical system Lo2 passes through the scanning lens 60CK, is then reflected by the reflecting mirror 81K, passes through the scanning lens 70K, and is emitted toward the photosensitive drum 5AK. The beam BK is imaged on the surface of the photosensitive drum 5AK and scanned in the main scanning direction.

[0085] As shown in FIG. 5, the light source devices LM1 and LM2 each further include a holder 300. In the present embodiment, the light source devices LM1 and LM2 have substantially the same structure. Hereinafter, the structure of the light source device LM1 will be described as a representative. For the light source device LM2, the relevant reference numerals are shown in parentheses in FIG. 5.

[0086] The holder 300 is a member that holds the light sources 10Y and 10M and the coupling lenses 20Y and 20M. The holder 300 includes a first holder 310 and a second holder 320 as a transparent part.

[0087] The first holder 310 holds the light sources 10Y and 10M and the coupling lens 20Y. The first holder 310 includes a light source holding part 311 and a lens holding part 312. The light source holding part 311 holds the light sources 10Y and 10M in a state arranged in the first direction.

[0088] The lens holding part 312 holds the coupling lens 20Y. The lens holding part 312 extends from one end of the light source holding part 311 on one side in the first direction toward one side in the third direction. The lens holding part 312 has a first seating surface 313 and two second seating surfaces 314.

[0089] The first seating surface 313 is a surface for holding the coupling lens 20Y. The coupling lens 20Y is fixed to the first seating surface 313 by an adhesive BD made of a photocurable resin such as an ultraviolet curable resin. The first seating surface 313 is located between the two second seating surfaces 314 in the second direction.

[0090] The second seating surface 314 is a surface for holding the second holder 320. The second holder 320 is fixed to the second seating surface 314 by the adhesive BD. The light source devices LM1, LM2 are installed on the frame 100 by fixing the first holder 310 to the frame 100 with screws SC (see FIG. 3).

[0091] The second holder 320 holds the coupling lens 20M. The second holder 320 has a base part 321 and two leg parts 322. The base part 321 has a cylindrical shape extending in the third direction. The coupling lens 20M is fixed to one end of the base part 321 in the third direction by an adhesive.

[0092] The two leg parts 322 extend from the base part 321 toward one side in the first direction. Specifically, one of the two leg parts 322 extends from one end of the base part 321 on one side in the second direction toward one side in the first direction, and the other of the two leg parts 322 extends from the other end of the base part 321 on the other side in the second direction toward one side in the first direction. Each leg part 322 has a flange part 322A extending from one end on one side in the first direction toward the other side of the other leg part 322 in the second direction.

[0093] The second holder 320 is transparent to the light emitted by the light sources 10Y and 10M. As an example, the second holder 320 is made of a resin that is transparent to the light emitted by the light sources 10Y and 10M. The second holder 320 is fixed to the first holder 310 by an adhesive BD.

[0094] As an example, when fixing the second holder 320 to the first holder 310, first, apply the adhesive BD to the second seating surface 314 of the first holder 310 or the flange portion 322A of the second holder 320. Next, place the second holder 320 on the second seating surface 314 of the first holder 310.

[0095] Thereafter, irradiate the adhesive BD through the flange portion 322A by directing light from the other side to one side in the first direction. As a result, the adhesive BD made of a photocurable resin cures, and the second holder 320 is fixed to the first holder 310. The second holder 320 is also transparent to light such as ultraviolet light for curing the adhesive BD.

[0096] As shown in FIG. 6, the second holder 320 has a recess 323 and a hole 324. The recess 323 is a recess through which the light emitted from the light source 10Y passes. The recess 323 has a concave shape from one side to the other side in the first direction. The recess 323 is formed by a base portion 321 and two leg portions 322. The recess 323 communicates in the third direction.

[0097] The hole 324 is a hole through which the light emitted from the light source 10M passes. The hole 324 is formed in the base portion 321. The hole 324 penetrates in the third direction.

[0098] The second holder 320 has an incident-side end face 325. The incident-side end face 325 is the end face of the second holder 320 on the side where the light emitted from the light sources 10Y and 10M is incident. In other words, the incident-side end face 325 is the end face on the other side of the second holder 320 in the third direction.

[0099] The incident-side end face 325 has a scattering surface 325A that scatters light. In FIG. 6, the scattering surface 325A is shown with dot hatching. The scattering surface 325A has a texture formed thereon. By forming the texture, reflection of light on the scattering surface 325A is suppressed. The scattering surface 325A can be formed, for example, by forming a texture on the surface of the mold that forms the second holder 320 and that forms the scattering surface 325A.

[0100] As shown in FIG. 7, the inner surface of the opening 32A formed in the second aperture wall 30B of the frame 100 has an inclined surface 32C. Specifically, in the opening 32A, the inner surface on one side in the second direction is the inclined surface 32C. The inclined surface 32C is inclined so as to move away from the optical axis X21 of the coupling lens 20Y as it approaches the polygon mirror 51 in the third direction.

[0101] The inner surface of the opening 32B of the second aperture wall 30B has an inclined surface 32D. Specifically, in the opening 32B, the inner surface on the other side in the second direction is the inclined surface 32D. The inclined surface 32D is inclined so as to move away from the optical axis X22 of the coupling lens 20K as it approaches the polygon mirror 51 in the third direction.

[0102] As shown in FIG. 8, the cover 200 has a light-shielding wall 220, a reinforcing wall 230, and first light-shielding walls 240A and 240B. The light-shielding wall 220, the reinforcing wall 230, and the first light-shielding walls 240A and 240B are walls that extend from the cover base wall 210 toward the other side in the first direction. The first light-shielding walls 240A and 240B extend in the third direction.

[0103] As shown in FIG. 9, the frame 100 has second light-shielding walls 120A and 120B, third light-shielding walls 130Y, 130M, 130C, and 130K (see also FIG. 4), and two recesses 140. The second light-shielding walls 120A and 120B are walls that extend from the frame base wall 110 toward one side in the first direction. The second light-shielding walls 120A and 120B and the third light-shielding walls 130Y, 130M, 130C, and 130K extend in the third direction.

[0104] One of the two recesses 140 is located between the polygon mirror 51 and the second light-shielding wall 120A in the second direction. The other of the two recesses 140 is located between the polygon mirror 51 and the second light-shielding wall 120B in the second direction. The recess 140 is a recess into which the convex portions 63 of the scanning lenses 60YM and 60CK shown in FIG. 10 fit.

[0105] In this embodiment, the scanning lenses 60YM and 60CK have substantially the same structure. Here, the structure of the scanning lens 60CK will be described as representative. The scanning lens 60CK has an incident surface 61, an exit surface 62, and a convex portion 63.

[0106] The incident surface 61 of the scanning lens 60CK is a concave curved surface with a shape that is concave on the other side in the second direction at the center in the third direction. The exit surface 62 of the scanning lens 60CK is a convex curved surface with a shape that protrudes on the other side in the second direction at the center in the third direction.

[0107] The convex portion 63 of the scanning lens 60CK protrudes from the center of the scanning lens 60CK in the third direction toward one side in the second direction. In other words, the convex portion 63 protrudes from the center of the scanning lens 60CK toward the polygon mirror 51 side in the third direction.

[0108] The scanning lenses 60YM and 60CK are fixed to the frame 100 in a state where the convex portions 63 are fitted into the recesses 140 of the frame 100 (see FIG. 9). The scanning lenses 60YM and CK are positioned with respect to the frame 100 because the convex portions 63 are fitted into the recesses 140.

[0109] As shown in FIG. 11, the light-shielding wall 220 extends from the cover base wall 210 toward the frame base wall 110. The light-shielding wall 220 extends to a position closer to the frame base wall 110 than the polygon mirror 51 in the first direction.

[0110] The light-shielding wall 220 is positioned between the coupling lenses 20Y, 20M, 20C, 20K and the polygon mirror 51 in the third direction. Specifically, the light-shielding wall 220 is positioned between the condenser lens 40 and the polygon mirror 51 in the third direction.

[0111] The light-shielding wall 220 has a first end face 221. The first end face 221 is the end face of the light-shielding wall 220 that is close to the frame base wall 110. Specifically, the first end face 221 is the end face on the other side of the light-shielding wall 220 in the first direction. The first end face 221 has an inclined surface 221A. The inclined surface 221A is inclined so as to approach the cover base wall 210 as it approaches the polygon mirror 51 in the third direction.

[0112] In the present embodiment, the first end face 221 of the light-shielding wall 220 is positioned between the polygon mirror 51 and the substrate 53 of the deflector 50 in the first direction. In other words, in the present embodiment, the light-shielding wall 220 does not extend up to the position of the substrate 53 in the first direction.

[0113] Similar to the light-shielding wall 220, the reinforcing wall 230 extends from the cover base wall 210 toward the frame base wall 110. Further, the reinforcing wall 230 is integrally formed with the light-shielding wall 220 and extends from the light-shielding wall 220 toward the polygon mirror 51. The end face 231 of the reinforcing wall 230 is inclined so as to approach the cover base wall 210 as it approaches the polygon mirror 51 in the third direction.

[0114] The deflector 50 further includes a substrate 53, a first capacitor 54, and a second capacitor 55 (see also FIG. 7). The motor 52, the first capacitor 54, and the second capacitor 55 are installed on the substrate 53 so as to protrude toward the cover base wall 210.

[0115] The first capacitor 54 and the second capacitor 55 are columnar electronic components that form part of the drive circuit of the motor 52. The first capacitor 54 and the second capacitor 55 are located between the light-shielding wall 220 and the polygon mirror 51 in the third direction. The light-shielding wall 220 overlaps with the first capacitor 54 when viewed from the third direction. Specifically, the end on the other side of the light-shielding wall 220 in the first direction overlaps with the end on one side of the first capacitor 54 when viewed from the third direction.

[0116] As shown in FIG. 12, the light-shielding wall 220, the reinforcing wall 230, and the first capacitor 54 are located between the optical axis X21 of the coupling lens 20Y and the optical axis X22 of the coupling lens 20K in the second direction. The second capacitor 55 overlaps with the optical axis X21 of the coupling lens 20K when viewed from the first direction. The beams BY, BM (see FIG. 11) from the condenser lens 40 toward the polygon mirror 51 pass through one side of the second capacitor 55 in the first direction.

[0117] The light-shielding wall 220 has a second end face 222 and a third end face 223. The second end face 222 and the third end face 223 are end faces of the light-shielding wall 220 in the second direction. Specifically, the second end face 222 is the end face on one side of the light-shielding wall 220 in the second direction, and the third end face 223 is the end face on the other side of the light-shielding wall 220 in the second direction.

[0118] The second end face 222 has an inclined surface 222A, and the third end face 223 has an inclined surface 223A. The inclined surfaces 222A, 223A are inclined so as to move away from the optical axis closer to the respective end faces 222, 223 among the optical axis X21 of the coupling lens 20Y and the optical axis X22 of the coupling lens 20K as they approach the polygon mirror 51 in the third direction.

[0119] Specifically, the inclined surface 222A is inclined so as to move away from the optical axis X21 as it approaches the polygon mirror 51 in the third direction. The inclined surface 223A is inclined so as to move away from the optical axis X22 as it approaches the polygon mirror 51 in the third direction.

[0120] The scanning optical device 4 further includes a cable 90. The cable 90 is a cable for supplying signals from the laser substrate 11 to the substrate 53 of the deflector 50. The laser substrate 11 is a substrate to which signals are supplied from the main substrate of the image forming apparatus 1, and the light sources 10Y, 10M, 10C, and 10K are installed thereon.

[0121] As shown in FIG. 7, one end of the cable 90 is connected to the substrate 53. Specifically, the cable 90 has a first connector 91 at one end. The first connector 91 is connected to the board connector 56. The board connector 56 is installed at the other end of the substrate 53 in the third direction.

[0122] As shown in FIG. 2, the other end of the cable 90 is connected to the laser substrate 11. Specifically, the cable 90 has a second connector 92 at the other end. The second connector 92 is connected to the connector 12 provided on the laser substrate 11.

[0123] As shown in FIG. 12, the cable 90 extends from the deflector 50 toward the other side in the third direction. The cable 90 extending from the deflector 50 passes through an opening 111 provided in the frame 100 (see also FIG. 2) and exits the frame 100.

[0124] The light shielding wall 220 overlaps a part of the cable 90 when viewed from the first direction. The light shielding wall 220 faces a part of the cable 90 in the first direction (see also FIG. 11).

[0125] The light shielding wall 220 does not overlap the substrate 53 when viewed from the first direction. Specifically, the light shielding wall 220 is closer to the coupling lenses 20Y, 20M, 20C, and 20K than the substrate 53 in the third direction. Specifically, the light shielding wall 220 is located on the other side in the third direction than the substrate 53. The light shielding wall 220 is located between the condenser lens 40 and the substrate 53 in the third direction.

[0126] The reinforcing wall 230 overlaps with the substrate 53 when viewed from the first direction. The reinforcing wall 230 faces the substrate 53 in the first direction. The reinforcing wall 230 is located on one side of the substrate 53 in the first direction (see also FIG. 11). In the present embodiment, the reinforcing wall 230 overlaps with the substrate connector 56 when viewed from the first direction.

[0127] The first light-shielding wall 240A is located between the polygon mirror 51 and the scanning lens 60YM in the second direction. The first light-shielding wall 240B is located between the polygon mirror 51 and the scanning lens 60CK in the second direction.

[0128] The second light-shielding wall 120A is located on the emission surface 62 side of the scanning lens 60YM in the second direction. In other words, the second light-shielding wall 120A is located on one side of the scanning lens 60YM in the second direction. The second light-shielding wall 120B is located on the emission surface 62 side of the scanning lens 60CK in the second direction. In other words, the second light-shielding wall 120B is located on the other side of the scanning lens 60CK in the second direction.

[0129] In the present embodiment, the first light-shielding walls 240A and 240B and their peripheries have a plane-symmetric structure with respect to a plane orthogonal to the second direction passing through the rotation axis X1 of the polygon mirror 51. Also, the second light-shielding walls 120A and 120B and their peripheries have a plane-symmetric structure with respect to a plane orthogonal to the second direction passing through the rotation axis X1 of the polygon mirror 51. Hereinafter, the structure of the first light-shielding wall 240B and the second light-shielding wall 120B and their peripheries will be described as representative.

[0130] The first light-shielding wall 240B has a shape that bends away from the rotation axis X1 of the polygon mirror 51 in the second direction when viewed from the first direction. Specifically, the first light-shielding wall 240B has a first portion 241, a second portion 242, a third portion 243, a fourth portion 244, and a fifth portion 245.

[0131] The first portion 241, the second portion 242, and the third portion 243 extend along the third direction. The first portion 241 faces the rotation axis X1 of the polygon mirror 51 in the second direction.

[0132] The second part 242 is located on the other side of the first part 241 in the third direction. The second part 242 is closer to the first light-shielding wall 240A than the first part 241 in the second direction. The second part 242 faces the center of the scanning lens 60CK in the third direction in the second direction. Specifically, the second part 242 faces the convex portion 63 (see FIG. 10(a)) of the scanning lens 60CK in the second direction.

[0133] The third part 243 is located on one side of the first part 241 in the third direction. The third part 243 is closer to the first light-shielding wall 240A than the first part 241 and the second part 242 in the second direction.

[0134] The fourth part 244 connects the first part 241 and the second part 242. The fourth part 244 extends obliquely with respect to the third direction so as to approach the first light-shielding wall 240A as it approaches the second part 242.

[0135] The fifth part 245 connects the first part 241 and the third part 243. The fifth part 245 extends obliquely with respect to the third direction so as to approach the first light-shielding wall 240A as it approaches the third part 243.

[0136] The distance D1 in the second direction from the rotation axis X1 of the polygon mirror 51 to the first part 241 is greater than the distance D2 in the second direction from the rotation axis X1 of the polygon mirror 51 to the second part 242. The first light-shielding wall 240B has a shape symmetric with respect to the third direction with the center of the second part 242 in the third direction as a reference, and as a whole, has a shape that bends away from the rotation axis X1 of the polygon mirror 51 in the second direction.

[0137] The second light-shielding wall 120B has a shape along the exit surface 62 of the scanning lens 60CK as viewed from the first direction. Specifically, the second light-shielding wall 120B has an arcuate shape that bends so that the center in the third direction protrudes to the other side in the second direction as viewed from the first direction.

[0138] As shown in FIG. 13, the first light-shielding wall 240B extends from the cover base wall 210 toward the frame base wall 110. The first light-shielding wall 240B has an end face 240E. The end face 240E is the end face of the first light-shielding wall 240B that is close to the frame base wall 110. The end face 240E of the first light-shielding wall 240B is located closer to the cover base wall 210 than the polygon mirror 51 in the first direction. That is, the first light-shielding wall 240B does not extend to the position between the polygon mirror 51 and the incident surface 61 of the scanning lens 60CK in the first direction.

[0139] The first light-shielding wall 240B extends to the position of the end of one side of the incident surface 61 in the first direction in the first direction. For this reason, the first light-shielding wall 240B overlaps the incident surface 61 of the scanning lens 60CK when viewed from the second direction. The end face 240E of the first light-shielding wall 240B is inclined so as to approach the cover base wall 210 as it approaches the scanning lens 60CK in the second direction.

[0140] The second light-shielding wall 120B extends from the frame base wall 110 toward the cover base wall 210. The second light-shielding wall 120B has an end face 120E. The end face 120E is the end face of the second light-shielding wall 120B that is close to the cover base wall 210. The end face 120E of the second light-shielding wall 120B is located closer to the frame base wall 110 than the polygon mirror 51 in the first direction. That is, the second light-shielding wall 120B does not extend to the position of the polygon mirror 51 in the first direction.

[0141] The second light-shielding wall 120B extends to the position of the end of the other side of the exit surface 62 of the scanning lens 60CK in the first direction in the first direction. For this reason, the second light-shielding wall 120B overlaps the exit surface 62 of the scanning lens 60CK when viewed from the second direction. The end face 120E of the second light-shielding wall 120B is inclined so as to approach the frame base wall 110 as it moves away from the scanning lens 60CK in the second direction.

[0142] Next, the third light-shielding walls 130Y, 130M (see FIG. 4), 130C, and 130K will be described. In the present embodiment, the third light-shielding walls 130Y, 130M and their peripheries, and the third light-shielding walls 130C, 130K and their peripheries have a substantially plane-symmetric structure with respect to a plane orthogonal to the second direction passing through the rotation axis X1 of the polygon mirror 51. Hereinafter, the structure of the third light-shielding walls 130C, 130K and their peripheries will be described as a representative.

[0143] The third light-shielding wall 130C is located between the reflection mirror 81C and the scanning lens 70C. Specifically, the third light-shielding wall 130C is located between the reflection mirror 81C and the scanning lens 70C in the first direction. Also, the third light-shielding wall 130C is located between the reflection mirror 81C and the scanning lens 70C in the second direction. Also, the third light-shielding wall 130C is located between the reflection mirror 81C and the scanning lens 70C in the third direction. The third light-shielding wall 130C overlaps the incident surface 71 of the scanning lens 70C when viewed from the first direction.

[0144] The third light-shielding wall 130C is located on the side opposite to the polygon mirror 51 across the optical axis X31 of the scanning lens 70C in the second direction. The optical axis X31 of the scanning lens 70C is located between the polygon mirror 51 and the third light-shielding wall 130C in the second direction.

[0145] The third light-shielding wall 130C has an end face 130E. The end face 130E is the end face of the third light-shielding wall 130C that is close to the optical axis X31 of the scanning lens 70C. The end face 130E is inclined so as to move away from the optical axis X31 of the scanning lens 70C as it approaches the scanning lens 70C.

[0146] The third light-shielding wall 130K is located between the reflection mirror 81K and the scanning lens 70K. Specifically, the third light-shielding wall 130K is located between the reflection mirror 81K and the scanning lens 70K in the first direction. Also, the third light-shielding wall 130K is located between the reflection mirror 81K and the scanning lens 70K in the second direction. Further, the third light-shielding wall 130K is located between the reflection mirror 81K and the scanning lens 70K in the third direction. The third light-shielding wall 130K overlaps with the incident surface 71 of the scanning lens 70K when viewed from the first direction.

[0147] The third light-shielding wall 130K is located on the side opposite to the polygon mirror 51 across the optical axis X32 of the scanning lens 70K in the second direction. The optical axis X32 of the scanning lens 70K is located between the polygon mirror 51 and the third light-shielding wall 130K in the second direction.

[0148] The third light-shielding wall 130K has an end face 130E. The end face 130E is the end face of the third light-shielding wall 130K that is close to the optical axis X32 of the scanning lens 70K. The end face 130E is inclined so as to move away from the optical axis X32 of the scanning lens 70K as it approaches the scanning lens 70K.

[0149] The scanning optical device 4 further includes elastic members 400A and 400B. The elastic member 400A is a member that fills the gap between the first light-shielding wall 240A and the scanning lens 60YM. The elastic member 400B is a member that fills the gap between the first light-shielding wall 240B and the scanning lens 60CK. As an example, the elastic members 400A and 400B are made of sponge.

[0150] In the present embodiment, the elastic members 400A and 400B and their peripheries have a substantially plane-symmetric structure with respect to a plane orthogonal to the second direction passing through the rotation axis X1 of the polygon mirror 51. Hereinafter, the structure of the elastic member 400B and its periphery will be described as a representative.

[0151] The elastic member 400B is located between the cover 200 and the scanning lens 60CK. Specifically, the elastic member 400B is located between the cover base wall 210 and the scanning lens 60CK.

[0152] More specifically, the cover base wall 210 has a seat surface 211. The elastic member 400B is located between the seat surface 211 and the scanning lens 60CK. The seat surface 211 is a surface that is substantially orthogonal to the first direction. The seat surface 211 extends from one end of the first light-shielding wall 240B in the first direction to the direction away from the rotation axis X1 of the polygon mirror 51 in the second direction. The seat surface 211 extends long in the third direction.

[0153] The elastic member 400B is fixed to the seat surface 211 by a double-sided tape or an adhesive. The elastic member 400B has a shape that is long in the third direction (see FIG. 8). The elastic member 400B is arranged in a state of being close to the first light-shielding wall 240B. The surface of the elastic member 400B facing the first light-shielding wall 240B has a shape along the first light-shielding wall 240B. In the present embodiment, the length of the elastic member 400B in the third direction is substantially the same as the length of the first light-shielding wall 240B in the third direction.

[0154] The elastic member 400B is positioned between the scanning lens 60CK and the seat surface 211 in a crushed state by assembling the frame 100 to which the scanning lens 60CK is fixed and the cover 200 to which the elastic member 400B is fixed to each other. The elastic member 400B closes the gap between the first light-shielding wall 240B and the scanning lens 60CK from one side in the first direction.

[0155] Next, the operation and effect of the embodiment will be described. As shown in FIG. 12, in the scanning optical device 4, for example, light from the light source 10Y may be reflected by the inner surface of the second holder 320, the wall of the frame 100, etc. to become stray light L1. When the stray light L1 is deflected by the polygon mirror 51, passes through the scanning optical system Lo2, and reaches the surface of the photosensitive drum 5AK, it may cause ghosts or the like in the image formed on the sheet S.

[0156] In the present embodiment, by having the light-shielding wall 220, the stray light L1 passing between the optical axis X21 of the coupling lens 20Y and the optical axis X22 of the coupling lens 20K can be blocked by the light-shielding wall 220.

[0157] Also, as shown in FIG. 11, since the cover 200 has the light-shielding wall 220, the degree of freedom in arranging the light-shielding wall 220 is increased because the light-shielding wall 220 is less likely to interfere with the deflector 50 and the like compared to the case where the frame 100 where the deflector 50 and the like are installed has a light-shielding wall. Thereby, the light-shielding wall 220 can be arranged at a position where stray light can be effectively blocked.

[0158] Since the light-shielding wall 220 extends to a position closer to the frame base wall 110 than the polygon mirror 51 in the first direction, it is possible to suppress stray light from reaching the polygon mirror 51 through between the light-shielding wall 220 and the frame base wall 110.

[0159] The beams BY, BM, BC, BK from the four coupling lenses 20 arranged in the first direction and the second direction are deflected by the deflector 50 and imaged on the surface of the photosensitive drum 5A by the corresponding scanning optical systems Lo1, Lo2, so that a plurality of stray lights derived from the light from the four light sources 10 can be effectively blocked by one light-shielding wall 220.

[0160] By refracting the beams BM, BC so that they approach the cover base wall 210 in the first direction by the condenser lens 40, the stray light derived from the light from the light sources 10M, 10C can also be refracted so as to approach the cover base wall 210 in the first direction by the condenser lens 40. And since the light-shielding wall 220 is positioned between the condenser lens 40 and the polygon mirror 51 in the third direction, even if the dimension of the light-shielding wall 220 in the first direction is reduced, the stray light derived from the light from the light sources 10M, 10C can be blocked. In other words, the light-shielding wall 220 can be miniaturized in the first direction.

[0161] By having the reinforcing wall 230, the light-shielding wall 220 can be reinforced by the reinforcing wall 230. Since the reinforcing wall 230 extending from the light-shielding wall 220 overlaps with the substrate 53 of the deflector 50 when viewed from the first direction, the light-shielding wall 220 can be arranged near the substrate 53. Thereby, it is possible to suppress stray light from reaching the polygon mirror 51 through between the light-shielding wall 220 and the substrate 53.

[0162] A first capacitor 54 protruding toward the cover base wall 210 is positioned between the light shielding wall 220 and the polygon mirror 51 in the third direction and between the optical axis X21 of the coupling lens 20Y and the optical axis X22 of the coupling lens 20K in the second direction, so that stray light passing between the optical axes X21 and X22 can also be blocked by the first capacitor 54.

[0163] By overlapping the first capacitor 54 when viewed from the third direction, the light shielding wall 220 can suppress stray light from reaching the polygon mirror 51 through between the light shielding wall 220 and the first capacitor 54.

[0164] By overlapping a part of the cable 90 when viewed from the first direction, the light shielding wall 220 can regulate the movement of the cable 90 when the cable 90 moves toward the light shielding wall 220 side.

[0165] By having inclined surfaces 221A to 223A on end faces 221 to 223 of the light shielding wall 220, it is possible to suppress light traveling from the light source 10 from being reflected by the end faces 221 to 223 of the light shielding wall 220 and becoming stray light.

[0166] By having a scattering surface 325A on the incident-side end face 325 of the second holder 320, it is possible to suppress light that has entered the holder 300 (second holder 320) from being internally reflected by the incident-side end face 325 of the second holder 320 and becoming stray light.

[0167] As shown in FIG. 7, by having inclined surfaces 32C and 32D on the inner surfaces of the openings 32A and 32B of the second aperture wall 30B, it is possible to suppress light traveling from the light source 10 from being reflected by the inner surfaces of the openings 32A and 32B and becoming stray light.

[0168] Further, as shown in FIG. 13, in the scanning optical device 4, for example, the beam BM deflected by the deflector 50 may be reflected by the incident surface 61 of the scanning lens 60YM to become stray light L2. Similarly, the beam BY deflected by the deflector 50 may be reflected by the incident surface 61 of the scanning lens 60YM to become stray light L3. If the stray light L2 reaches the surface of the photosensitive drum 5AC through the scanning optical system Lo2, or if the stray light L3 reaches the surface of the photosensitive drum 5AK through the scanning optical system Lo2, it may cause ghosts or the like in the image formed on the sheet S.

[0169] In this embodiment, by having the first light shielding wall 240B, the first light shielding wall 240B can block the stray light L2. Also, by having the second light shielding wall 120B, the second light shielding wall 120B can block the stray light L3.

[0170] Similarly, by having the first light shielding wall 240A, the first light shielding wall 240A can block the beam BC (stray light) reflected by the incident surface 61 of the scanning lens 60CK. By having the second light shielding wall 120A, the second light shielding wall 120A can block the beam BK (stray light) reflected by the incident surface 61 of the scanning lens 60CK.

[0171] Also, in this embodiment, the second light shielding walls 120A and 120B extending from the frame base wall 110 where the deflector 50 is installed are located on the emission surface 62 side of the scanning lenses 60YM and 60CK, so that the distance from the polygon mirror 51 to the second light shielding walls 120A and 120B can be ensured. Thereby, the generation of noise associated with the rotation of the polygon mirror 51 can be suppressed.

[0172] By having the third light shielding wall 130C, the stray light L2 that could not be blocked by the first light shielding wall 240B can be blocked by the third light shielding wall 130C. By having the third light shielding wall 130K, the stray light L3 that could not be blocked by the second light shielding wall 120B can be blocked by the third light shielding wall 130K.

[0173] Similarly, by having the third light-shielding wall 130M, stray light derived from the beam BC that could not be blocked by the first light-shielding wall 240A can be blocked by the third light-shielding wall 130M. By having the third light-shielding wall 130Y, stray light derived from the beam BK that could not be blocked by the second light-shielding wall 120A can be blocked by the third light-shielding wall 130Y.

[0174] The end faces 240E of the first light-shielding walls 240A and 240B that are close to the frame base wall 110 are inclined so as to approach the cover base wall 210 as they approach the corresponding scanning lenses 60YM and 60CK in the second direction, thereby suppressing the reflection of the light that has traveled from the light source devices LM1 and LM2 at the end face 240E.

[0175] The end faces 120E of the second light-shielding walls 120A and 120B that are close to the cover base wall 210 are inclined so as to approach the frame base wall 110 as they move away from the corresponding scanning lenses 60YM and 60CK in the second direction, thereby suppressing the reflection of the light that has traveled from the light source devices LM1 and LM2 at the end face 120E.

[0176] The end face 130E of the third light-shielding wall 130C that is close to the optical axis X31 of the scanning lens 70C is inclined so as to move away from the optical axis X31 as it approaches the scanning lens 70C, thereby suppressing the reflection of the light that has traveled from the light source device LM2 at the end face 130E of the third light-shielding wall 130C. The end face 130E of the third light-shielding wall 130K that is close to the optical axis X32 of the scanning lens 70K is inclined so as to move away from the optical axis X32 as it approaches the scanning lens 70K, thereby suppressing the reflection of the light that has traveled from the light source device LM2 at the end face 130E of the third light-shielding wall 130K.

[0177] The third light-shielding wall 130C is located on the side opposite to the polygon mirror 51 across the optical axis X31 of the scanning lens 70C in the second direction, so that the scanning lens 70C can be arranged closer to the scanning lens 60CK. As a result, the frame 100 can be miniaturized, and thus the scanning optical device 4 can be miniaturized.

[0178] By providing the scanning optical device 4 with elastic members 400A and 400B that close the gaps between the first light-shielding walls 240A and 240B and the corresponding scanning lenses 60YM and 60CK, it is possible to suppress dust from entering the scanning optical device 4 through the gaps between the cover 200 and the scanning lenses 60YM and 60CK by the elastic members 400A and 400B. Further, it is possible to suppress stray light from passing between the first light-shielding walls 240A and 240B and the corresponding scanning lenses 60YM and 60CK by the elastic members 400A and 400B.

[0179] As shown in FIG. 12, since the first light-shielding walls 240A and 240B have a shape that bends away from the rotation axis X1 of the polygon mirror 51 in the second direction when viewed from the first direction, a distance in the second direction from the polygon mirror 51 to the first light-shielding walls 240A and 240B can be ensured. Thereby, generation of noise associated with the rotation of the polygon mirror 51 can be further suppressed.

[0180] In other words, since the distance D1 in the second direction from the rotation axis X1 to the first portion 241 of the first light-shielding walls 240A and 240B is greater than the distance D2 in the second direction from the rotation axis X1 to the second portion 242, a distance in the second direction from the polygon mirror 51 to the first light-shielding walls 240A and 240B can be ensured. Thereby, generation of noise associated with the rotation of the polygon mirror 51 can be further suppressed.

[0181] Since the frame 100 has recesses 140 into which the convex portions 63 of the scanning lenses 60YM and 60CK fit, the scanning lenses 60YM and 60CK can be positioned with respect to the frame 100.

[0182] Since the second light-shielding walls 120A and 120B have a shape that follows the emission surfaces 62 of the corresponding scanning lenses 60YM and 60CK when viewed from the first direction, the second light-shielding walls 120A and 120B can be provided compactly along the scanning lenses 60YM and 60CK. Thereby, the frame 100 can be miniaturized, and thus the scanning optical device 4 can be miniaturized.

[0183] Although the embodiments have been described above, the scanning optical device and the image forming device can be appropriately modified and implemented as exemplified below.

[0184] For example, as shown in FIG. 14(a), in the scanning optical device 4, since the light shielding wall 220 is closer to the coupling lenses 20Y, 20M, 20C, 20K than the substrate 53 of the deflector 50 in the third direction, a configuration is possible in which the light shielding wall 220 extending from the cover base wall 210 extends to the position of the substrate 53 in the first direction.

[0185] Also, as shown in FIG. 14(b), a configuration is also possible in which the light shielding wall 220 extending from the cover base wall 210 extends to a position closer to the frame base wall 110 than the substrate 53 in the first direction. According to the configurations shown in FIGS. 14(a) and 14(b), it is possible to suppress stray light from reaching the polygon mirror 51 through the space between the light shielding wall 220 and the frame base wall 110.

[0186] Also, as shown in FIG. 15, instead of the incident side end face 325, the second holder 320 of the holder 300 may have scattering surfaces 323A and 324A on the inner surface of the recess 323 and the inner surface of the hole 324 that scatter light. By having the scattering surfaces 323A and 324A on the inner surface of the recess 323 and the inner surface of the hole 324 of the holder 300, it is possible to suppress light from being reflected by the inner surface of the holder 300 and becoming stray light.

[0187] In the above embodiment, the second holder 320 (holder 300) has the recess 323 through which the light emitted from the light sources 10Y and 10K passes. However, for example, the holder may have a hole through which the light emitted from the light sources 10Y and 10K passes. In this case, the inner surface of the hole may have a scattering surface that scatters light, similar to the inner surface of the hole 324 shown in FIG. 15. Thereby, it is possible to suppress light from being reflected by the inner surface of the holder and becoming stray light. Note that the holder may have a configuration without a scattering surface.

[0188] In the above embodiment, the holder 300 has the second holder 320 (transparent portion) that is transparent to the light emitted from the light source 10. However, for example, the holder may be configured not to have a transparent portion.

[0189] In the above embodiment, the frame 100 has the first aperture wall 30A and the second aperture wall 30B. However, for example, the cover may have the first aperture wall and the second aperture wall. Also, the frame may have one of the first aperture wall and the second aperture wall, and the cover may have the other of the first aperture wall and the second aperture wall.

[0190] In the above embodiment, the first end face 221 of the light shielding wall 220 is inclined to suppress light reflection. However, for example, the first end face may not be inclined. The same applies to the second end face and the third end face of the light shielding wall. The same also applies to the end faces of the first light shielding wall, the second light shielding wall, and the third light shielding wall. The same also applies to the inner surface of the aperture of the aperture wall.

[0191] In the above embodiment, the light shielding wall 220 is configured to overlap a part of the cable 90 when viewed from the first direction. However, for example, the light shielding wall may be configured not to overlap the cable when viewed from the first direction.

[0192] In the above embodiment, the light shielding wall 220 is configured to overlap the first capacitor 54 when viewed from the third direction. However, for example, the light shielding wall may be configured not to overlap the capacitor when viewed from the third direction.

[0193] In the above embodiment, the first capacitor 54 is located between the optical axis X21 of the coupling lens 20Y and the optical axis X22 of the coupling lens 20K. However, for example, the capacitor may not be located between the optical axes X21 and X22.

[0194] In the above embodiment, the light shielding wall 220 is closer to the coupling lens 20 than the substrate 53 of the deflector 50 in the third direction. However, for example, the light shielding wall may overlap the substrate of the deflector when viewed from the first direction.

[0195] In the above-described embodiment, the light-shielding wall 220 extends to a position closer to the frame base wall 110 than the polygon mirror 51 in the first direction. However, for example, the light-shielding wall may not extend up to the polygon mirror in the first direction.

[0196] In the above-described embodiment, the reinforcing wall 230 overlaps with the substrate 53 of the deflector 50 when viewed from the first direction. However, for example, the reinforcing wall may not overlap with the substrate of the deflector when viewed from the first direction.

[0197] In the above-described embodiment, the cover 200 has the reinforcing wall 230. However, for example, the cover may not have the reinforcing wall. Also, in the above-described embodiment, the cover 200 has the light-shielding wall 220. However, for example, the cover may not have the light-shielding wall.

[0198] In the above-described embodiment, the third light-shielding wall 130C is located on the side opposite to the polygon mirror 51 with the optical axis X31 of the scanning lens 70C interposed therebetween in the second direction. However, for example, it may be located on the same side as the polygon mirror 51 with respect to the optical axis X31. The same applies to the other third light-shielding walls 130Y, 130M, and 130K.

[0199] In the above-described embodiment, the second light-shielding walls 120A and 120B have an arcuate shape along the emission surfaces 62 of the corresponding scanning lenses 60YM and 60CK. However, for example, the second light-shielding wall may have a linear shape along the third direction.

[0200] In the above-described embodiment, the frame 100 has the third light-shielding walls 130Y, 130M, 130C, and 130K. However, for example, the frame may not have the third light-shielding walls. Also, in the above-described embodiment, the scanning optical device 4 has the first light-shielding walls 240A and 240B and the second light-shielding walls 120A and 120B. However, for example, the scanning optical device may have only one of the first light-shielding wall and the second light-shielding wall. Also, the scanning optical device may not have the first light-shielding wall and the second light-shielding wall.

[0201] In the above embodiment, the convex portions 63 of the scanning lenses 60YM and 60CK protruded toward the polygon mirror 51. However, for example, the convex portions may protrude toward the side opposite to the polygon mirror.

[0202] In the above embodiment, the scanning optical device 4 was arranged in the main body housing 2 of the image forming apparatus 1 such that the frame base wall 110 was positioned above the deflector 50 and the cover base wall 210 was positioned below the deflector 50. However, for example, it may be arranged such that the up and down positions are reversed from those of the above embodiment.

[0203] In the above embodiment, the image forming apparatus 1 was a printer. However, for example, the image forming apparatus may be a copying machine or a multifunction machine. Further, the scanning optical device may be used outside of the image forming apparatus.

[0204] Each of the elements described in the above embodiment and modification examples may be implemented in any combination.

Description of Reference Numerals

[0205] 1 Image forming apparatus 4 Scanning optical device 5AC Photosensitive drum 5AK Photosensitive drum 5AM Photosensitive drum 5AY Photosensitive drum 50 Deflector 51 Polygon mirror 60CK Scanning lens 60YM Scanning lens 61 Incident surface 62 Exit surface 100 Frame 110 Frame base wall 120A Second light shielding wall 120B Second light shielding wall 200 Cover 210 Cover base wall 240A First light shielding wall 240B First light shielding wall BC beam BK beam BM beam BY 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 that deflects the first beam and the second beam, the deflector having a polygon mirror that is 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 into 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 having a second scanning lens into 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 side opposite to the frame base wall in the first direction, The cover is a first light-shielding wall that extends from the cover base wall toward the frame base wall, is a first light-shielding wall located between the polygon mirror and the first scanning lens, and has a first light-shielding wall that overlaps the incident surface of the first scanning lens when viewed from the second direction, The frame is a second light-shielding wall that extends from the frame base wall toward the cover base wall, is a second light-shielding wall located on the emission surface side of the first scanning lens, and has a second light-shielding wall that overlaps the emission surface of the first scanning lens when viewed from the second direction. A scanning optical device characterized by this.

2. The end face of the first light-shielding wall close to the frame base wall is located closer to the cover base wall than the polygon mirror in the first direction, The scanning optical device according to claim 1, wherein the end face of the second light-shielding wall close to the cover base wall is located closer to the frame base wall than the polygon mirror in the first direction.

3. The scanning optical device according to claim 1, wherein the first light-shielding wall has a shape that bends away from the rotation axis of the polygon mirror in the second direction when viewed from the first direction.

4. The first light-shielding wall is A first portion facing the rotation axis of the polygon mirror in the second direction, The first scanning lens has a third part at the center in a third direction orthogonal to both the first direction and the second direction, and a second part facing the second direction. The scanning optical device according to claim 1, wherein a distance in the second direction from the rotation axis of the polygon mirror to the first part is greater than a distance in the second direction from the rotation axis of the polygon mirror to the second part.

5. The first scanning lens has a convex portion protruding toward the polygon mirror side from the center of the first scanning lens in the third direction. The scanning optical device according to claim 4, wherein the frame has a concave portion into which the convex portion fits.

6. The scanning optical device according to claim 1, wherein an end face of the first light-shielding wall close to the frame base wall is inclined so as to approach the cover base wall as it approaches the first scanning lens in the second direction.

7. An exit surface of the first scanning lens is a convex surface shaped such that a center in a third direction orthogonal to both the first direction and the second direction protrudes in the second direction. The scanning optical device according to claim 1, wherein the second light-shielding wall has a shape that follows the exit surface of the first scanning lens when viewed from the first direction.

8. The scanning optical device according to claim 1, wherein an end face of the second light-shielding wall close to the cover base wall is inclined so as to approach the frame base wall as it moves away from the first scanning lens in the second direction.

9. The first scanning optical system includes a reflection mirror that reflects a first beam that has passed through the first scanning lens toward the first surface to be scanned, and a third scanning lens that forms an image of the first beam reflected by the reflection mirror on the first surface to be scanned. The scanning optical device according to claim 1, wherein the frame is a third light-shielding wall extending in a third direction orthogonal to both the first direction and the second direction, the third light-shielding wall being located between the reflection mirror and the third scanning lens, and having a third light-shielding wall that overlaps the entrance surface of the third scanning lens when viewed from the first direction.

10. The scanning optical device according to claim 9, wherein the third light-shielding wall is located on the side opposite to the polygon mirror with respect to the optical axis of the third scanning lens in the second direction.

11. The scanning optical device according to claim 9, wherein an end face of the third light-shielding wall close to the optical axis of the third scanning lens is inclined so as to move away from the optical axis of the third scanning lens as it approaches the third scanning lens.

12. The scanning optical device according to claim 1, further comprising an elastic member positioned between the cover and the first scanning lens, the elastic member closing a gap between the first light-shielding wall and the first scanning lens.

13. An image forming apparatus comprising the scanning optical device according to any one of claims 1 to 12, wherein the scanning optical device is arranged such that the frame base wall is positioned above the deflector and the cover base wall is positioned below the deflector.

Images