Scanning optical device

Abstract

The present invention provides a scanning optical device that can maintain the distance between the polygon mirror and the contact wall even when the distance between the polygon mirror and the scanning lens is reduced. [Solution] The scanning optical device comprises an optical deflector 50 having a polygon mirror 51, a scanning optical system having a scanning lens 60CK into which the beam deflected by the optical deflector 50 is incident, a frame 100 supporting the optical deflector 50 and the scanning lens 60CK, and a leaf spring 400 fixing the scanning lens 60CK to the frame 100. The scanning lens 60CK has a flange 62 extending from the end of the lens portion. The frame 100 has a contact wall 130 that is further from the axis of rotation X1 than the flange 62 in a second direction. The leaf spring 400 has a base 410 that contacts the contact wall 130 from the opposite side of the flange 62 in a second direction, and a first arm 420 that extends from one end of the base 410 in a first direction and sandwiches the contact wall 130 and the flange 62 between itself and the base 410.

Description

Technical Field

[0001] The present invention relates to a scanning optical device.

Background Art

[0002] Conventionally, as a scanning optical device, there is known one including a polygon mirror, a scanning lens into which a beam deflected by the polygon mirror is incident, a frame that supports the scanning lens, and a leaf spring that fixes the scanning lens to the frame (Patent Document 1). In this technology, the frame has an abutting wall on the polygon mirror side of the scanning lens. The leaf spring is attached to the frame so as to sandwich the abutting wall and the longitudinal end of the scanning lens.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, when the scanning optical device is miniaturized, the distance between the polygon mirror and the scanning lens becomes small, so the distance between the polygon mirror and the abutting wall also becomes small. In the conventional configuration, since the abutting wall is disposed on the polygon mirror side of the scanning lens, for example, when attaching the leaf spring to the frame, the leaf spring may interfere with the polygon mirror.

[0005] Therefore, it is desired that the distance between the polygon mirror and the abutting wall can be ensured even when the distance between the polygon mirror and the scanning lens becomes small.

Means for Solving the Problems

[0006] The scanning optical device includes a light source device, a light deflector, a scanning optical system, a frame, and a leaf spring. The light source device emits a beam. The optical deflector deflects the beam in the primary scanning direction. The optical deflector has a polygonal mirror that is rotatable about a rotation axis extending in a first direction perpendicular to the primary scanning direction. A scanning optical system images a beam deflected by an optical deflector onto the surface to be scanned. The scanning optical system has a scanning lens into which the beam deflected by the optical deflector is incident. The frame supports the optical deflector and scanning lens. The leaf spring secures the scanning lens to the frame. The scanning lens comprises a lens section and a flange. The flange extends from the end of the lens section in the main scanning direction. The frame has abutment walls. The contact wall is in contact with the flange in a second direction perpendicular to both the main scanning direction and the first direction. In the second direction, the contact wall is further from the axis of rotation than the flange. The leaf spring has a base and a first arm. The base contacts the abutment wall from the opposite direction to the flange in the second direction. The first arm extends from one end of the base in a first direction and sandwiches the contact wall and flange between itself and the base. The first arm biases the flange toward the contact wall.

[0007] Because the contact wall is further from the rotation axis of the polygon mirror than the flange in the second direction, the distance between the polygon mirror and the contact wall can be maintained even when the distance between the polygon mirror and the scanning lens is reduced.

[0008] The first arm may have two arm sections. The two arm sections extend from one end of the base in the first direction and sandwich the contact wall and flange between them and the base. The two arm sections are spaced apart in the main scanning direction.

[0009] The first arm has two arm sections, which ensures that the load is applied when the flange is biased toward the contact wall.

[0010] The first arm may have a connecting portion. The connecting portion extends in the main scanning direction. The connecting portion connects the end of one arm section furthest from the base to the end of the other arm section furthest from the base.

[0011] The first arm has a connecting section that links two arm sections, allowing the two arm sections of the first arm to operate as a single unit when attaching the leaf spring to the frame. This makes it easier to attach the leaf spring to the frame.

[0012] The leaf spring may have a second arm. The second arm extends from one end of the base in the first direction. The second arm is positioned between the two arm sections in the main scanning direction and contacts one end of the flange in the first direction, biasing the flange toward the other end in the first direction.

[0013] The leaf spring has a first arm and a second arm, so that one leaf spring can bias the flange toward the contact wall in a second direction and also bias the flange in a first direction.

[0014] The optical deflector has a substrate that supports a polygon mirror, and the leaf spring does not need to overlap with the substrate when viewed from the first direction.

[0015] By ensuring that the leaf spring does not overlap with the substrate of the optical deflector when viewed from the first direction, interference between the leaf spring and the optical deflector can be suppressed when the leaf spring and optical deflector are mounted on the frame along the first direction.

[0016] The flange may include a first flange and a second flange, the abutment wall may include a first abutment wall and a second abutment wall, and the leaf spring may include a first leaf spring and a second leaf spring. The first flange extends from one end of the lens portion in the main scanning direction. The second flange extends from the other end of the lens section in the main scanning direction. The first flange abuts against the first abutment wall. The second abutting wall is abutted by the second flange. The first leaf spring sandwiches the first abutting wall and the first flange. The second leaf spring sandwiches the second abutting wall and the second flange. At least one of the first leaf spring and the second leaf spring may be located between one end and the other end of the substrate in the main scanning direction.

[0017] By having at least one of the first leaf spring and the second leaf spring located between one end and the other end of the substrate in the main scanning direction, the scanning lens, the first leaf spring, the second leaf spring, and the optical deflector can be arranged compactly in the main scanning direction.

[0018] The frame may have a plurality of ribs. The plurality of ribs extend in the first direction. The plurality of ribs are arranged side by side in the main scanning direction. The plurality of ribs contact the substrate in the second direction when attaching the optical deflector to the frame and guide the movement of the substrate.

[0019] By having the frame have a plurality of ribs that guide the movement of the substrate when attaching the optical deflector to the frame, it is possible to suppress the optical deflector from interfering with the leaf spring when attaching the optical deflector to the frame.

[0020] The frame may have a plurality of ribs on both sides of the substrate in the second direction, respectively.

[0021] By having the frame have a plurality of ribs on both sides of the substrate in the second direction, respectively, it is possible to further suppress the optical deflector from interfering with the leaf spring when attaching the optical deflector to the frame.

[0022] The scanning lens has an incident surface on which the beam deflected by the optical deflector is incident, and the incident surface may be a concave surface.

[0023] Because the incident surface of the scanning lens is concave, even when the distance between the polygon mirror and the scanning lens is small, space can be secured between the polygon mirror and the incident surface of the scanning lens. [Effects of the Invention]

[0024] Even if the distance between the optical deflector and the scanning lens is reduced, the distance between the optical deflector and the contact wall can be maintained. [Brief explanation of the drawing]

[0025] [Figure 1] This is a cross-sectional view showing an image forming apparatus equipped with a scanning optical device. [Figure 2] This is a perspective view showing a scanning optical device. [Figure 3] This is a cross-sectional view of XX in Figure 2. [Figure 4] This is a cross-sectional view of the YY direction in Figure 2. [Figure 5] This is a view of the scanning optical device with the cover removed, seen from one of the first directions. [Figure 6] This is a perspective view showing the area around the optical deflector of a scanning optical device. [Figure 7] This is a perspective view showing the area near the frame's contact wall, as well as the optical deflector, scanning lens, and leaf spring. [Figure 8] This is a view of the area near the scanning lens of a scanning optical device, seen from one side in the main scanning direction. [Figure 9] These are perspective views (a) and (b) showing a leaf spring. [Figure 10] This is a view of the area near the optical deflector of a scanning optical device, seen from one direction in the first direction. [Figure 11] This is a perspective view showing the substrate guide ribs of the frame. [Modes for carrying out the invention]

[0026] Next, embodiments will be described. As shown in Figure 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 comprises 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 ejection unit 9.

[0027] The main housing 2 comprises a front cover 2A and an output tray 2B. The front cover 2A opens and closes the opening on the front side of the main housing 2.

[0028] The sheet supply unit 3 is located at the bottom of the main body housing 2. The sheet supply unit 3 comprises a sheet tray 3A and a sheet supply mechanism 3B. The sheet tray 3A holds 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.

[0029] The scanning optical device 4 is located at the top of the main housing 2. The scanning optical device 4 emits a beam, indicated by the dashed line, to expose the surface of the photosensitive drum 5A.

[0030] The drum unit 5 is located within the main housing 2, between the sheet tray 3A and the scanning optical unit 4. The drum unit 5 is detachable from the main housing 2 through an opening in the main housing 2, which 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.

[0031] In this embodiment, the photosensitive drum 5A includes 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 photosensitive drum 5AY, photosensitive drum 5AM, photosensitive drum 5AC, and photosensitive drum 5AK from front to back, or in other words, from upstream to downstream in the conveying direction of the sheet S.

[0032] The developing cartridge 6 is detachable from the drum frame 5C of the drum unit 5. Each developing cartridge 6 comprises a developing roller 6A, a supply roller 6B, a layer thickness regulating blade 6D, a toner storage section 6E for storing toner, and an agitator 6F.

[0033] The agitator 6F stirs the toner in the toner storage section 6E. The agitator 6F also supplies the toner from the toner storage section 6E to the supply roller 6B. The supply roller 6B supplies the toner to the developer roller 6A. The layer thickness regulating blade 6D regulates the thickness of the toner on the developer roller 6A to a constant thickness.

[0034] The developer cartridge 6 contains toners of different colors. In this embodiment, the developer cartridge 6 includes 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.

[0035] The transfer unit 7 is located between the sheet tray 3A and the drum unit 5. The transfer unit 7 comprises 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 located inside the transfer belt 7C. The transfer rollers 7D sandwich the transfer belt 7C between themselves and the photosensitive drum 5A.

[0036] The fixing device 8 is located behind the drum unit 5. The fixing device 8 comprises 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.

[0037] 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. This forms an electrostatic latent image on the photosensitive drum 5A. The developing roller 6A supplies toner to the photosensitive drum 5A. This forms a toner image on the photosensitive drum 5A.

[0038] 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.

[0039] The sheet discharge unit 9 includes a transport roller 9A and an 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 into the discharge tray 2B.

[0040] As shown in Figure 2, the scanning optical device 4 comprises a housing H, an incident optical system Li, an optical deflector 50, and scanning optical systems Lo1 and Lo2. In the referenced drawings, the direction with an arrow indicates one of the main scanning direction, the first direction, and the second direction, while the direction without an arrow indicates the other.

[0041] The first direction is perpendicular to the main scanning direction. In this embodiment, the first direction is the direction in which the rotation axis X1 of the polygon mirror 51 of the optical deflector 50 extends. The second direction is perpendicular to both the main scanning direction and the first direction.

[0042] As shown in Figure 3, the housing H comprises 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 optical deflector 50 is installed.

[0043] 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 optical 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 optical deflector 50 from one side in the first direction.

[0044] In this embodiment, the scanning optical apparatus 4 is positioned within the main body housing 2 of the image forming apparatus 1 (see Figure 1) such that the frame base wall 110 is located above the optical deflector 50 and the cover base wall 210 is located below the optical deflector 50. That is, in this embodiment, the first direction corresponds to the vertical direction of the image forming apparatus 1. More specifically, one side of the first direction corresponds to the lower side of the image forming apparatus 1, and the other side of the first direction corresponds to the upper side of the image forming apparatus 1.

[0045] The incident optical system Li comprises light source devices LM1 and LM2, an aperture wall 30, and a focusing lens 40. 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.

[0046] As shown in Figure 2, the light source devices LM1 and LM2 each comprise two light sources 10 and two coupling lenses 20. Specifically, light source device LM1 comprises light source 10Y, light source 10M, coupling lens 20Y, and coupling lens 20M. Light source device LM2 comprises light source 10C, light source 10K, coupling lens 20C, and coupling lens 20K.

[0047] In this embodiment, the light source 10 is a semiconductor laser that emits laser light. The light source 10Y emits laser light to expose the yellow photosensitive drum 5AY. The light source 10M emits laser light to expose the magenta photosensitive drum 5AM. The light source 10C emits laser light to expose the cyan photosensitive drum 5AC. The light source 10K emits laser light to expose the black photosensitive drum 5AK.

[0048] Coupling lens 20Y converts the laser light emitted from light source 10Y into beam BY. Coupling lens 20M converts the laser light emitted from light source 10M into beam BM. Coupling lens 20C converts the laser light emitted from light source 10C into beam BC. Coupling lens 20K converts the laser light emitted from light source 10K into beam BK.

[0049] As shown in Figure 3, the focusing 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 focuses them onto the mirror surface of the polygon mirror 51. In the incident optical system Li, the sub-scanning direction corresponds to the first direction.

[0050] In this embodiment, the focusing lens 40 is a cylindrical lens with a cylindrical incident surface and a flat exit surface. The focusing lens 40 refracts beams BY and BK so that they approach the frame base wall 110 in the first direction and focuses them onto the mirror surface of the polygon mirror 51. The focusing lens 40 also refracts beams BM and BC so that they approach the cover base wall 210 in the first direction and focuses them onto the mirror surface of the polygon mirror 51.

[0051] The diaphragm wall 30 includes a first diaphragm wall 30A and a second diaphragm wall 30B. In this embodiment, the first diaphragm wall 30A and the second diaphragm wall 30B are integrally formed with the frame 100. That is, the frame 100 has the first diaphragm wall 30A and the second diaphragm wall 30B.

[0052] The first aperture wall 30A is a wall located between the coupling lenses 20Y, 20M, 20C, 20K and the focusing lens 40. The first aperture wall 30A has an aperture 31 (see Figure 2). The aperture 31 includes an aperture 31Y through which the beam BY from the coupling lens 20Y toward the polygon mirror 51 passes, an aperture 31M through which the beam BM from the coupling lens 20M toward the polygon mirror 51 passes, an aperture 31C through which the beam BC from the coupling lens 20C toward the polygon mirror 51 passes, and an aperture 31K through which the beam BK from the coupling lens 20K toward the polygon mirror 51 passes.

[0053] The second aperture wall 30B is a wall located between the focusing lens 40 and the optical deflector 50. The focusing lens 40 is located between the first aperture wall 30A and the second aperture wall 30B. The second aperture wall 30B has two apertures 32A and 32B (see also Figure 5). Aperture 32A is the aperture through which beams BY and BM, which are directed from coupling lenses 20Y and 20M toward the polygon mirror 51, pass. Aperture 32B is the aperture through which beams BC and BK, which are directed from coupling lenses 20C and 20K toward the polygon mirror 51, pass.

[0054] The optical deflector 50 is a device that deflects the beams BY, BM, BC, and BK in the main scanning direction. The optical deflector 50 includes a polygon mirror 51, a motor 52, and a substrate 53.

[0055] The polygon mirror 51 is rotatable around a rotation axis X1 extending in the first direction. The polygon mirror 51 has five mirror surfaces equidistant from the rotation axis X1 (see also Figure 2). By rotating, the polygon mirror 51 deflects the beams BY, BM, BC, and BK in the main scanning direction.

[0056] Motor 52 is a motor that rotates the polygon mirror 51. Motor 52 is fixed to the frame 100 via a circuit board 53.

[0057] The substrate 53 is made of a metal plate and supports the polygon mirror 51 and the motor 52. More specifically, the substrate 53 supports the bearing 51B and the motor 52. The bearing 51B is a bearing that rotatably supports the shaft 51A of the polygon mirror 51. The substrate 53 also supports a circuit board (not shown) on which the drive circuit for the motor 52 and other components are formed.

[0058] As shown in Figure 4, the scanning optical systems Lo1 and Lo2 are optical systems that image the beams BY, BM, BC, and BK, which have been deflected by the optical deflector 50, onto the surface of the photosensitive drum 5A. In this embodiment, the surface of the photosensitive drum 5A corresponds to the "surface to be scanned".

[0059] The scanning optical system Lo1 images beam BY, which is deflected by the optical deflector 50, onto the surface of the photosensitive drum 5AY, and also images beam BM, which is deflected by the optical deflector 50, onto the surface of the photosensitive drum 5AM. The scanning optical system Lo2 images beam BC, which is deflected by the optical deflector 50, onto the surface of the photosensitive drum 5AC, and also images beam BK, which is deflected by the optical deflector 50, onto the surface of the photosensitive drum 5AK. The polygon mirror 51 is located between the scanning optical system Lo1 and the scanning optical system Lo2 in the second direction.

[0060] The scanning optical system Lo1 has scanning lenses 60YM, 70Y, and 70M, and mirrors 81Y, 81M, and 82M. The scanning optical system Lo2 has scanning lenses 60CK, 70C, and 70K, and mirrors 81C, 81K, and 82C. Each component constituting the scanning optical systems Lo1 and Lo2 is fixed to the frame 100.

[0061] Scanning lens 60YM is the lens to which beams BY and BM, which have been deflected by the optical deflector 50, are incident, and scanning lens 60CK is the lens to which beams BC and BK, which have been deflected by the optical deflector 50, are incident.

[0062] The scanning lenses 60YM and 60CK refract the beams BY, BM, BC, and BK, which have been deflected by the optical deflector 50, in the main scanning direction, thereby forming an image on the surface of the photosensitive drum 5A. Furthermore, the scanning lenses 60YM and 60CK have an fθ characteristic that allows them to scan the beams BY, BM, BC, and BK, which have been deflected at a constant angular velocity by the optical deflector 50, at a constant velocity on the surface of the photosensitive drum 5A.

[0063] The scanning lens 60YM and the scanning lens 60CK are arranged symmetrically with respect to a plane perpendicular to a 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.

[0064] Mirror 81Y is a mirror that reflects the beam BY, which has passed through the scanning lens 60YM, toward the surface of the photosensitive drum 5AY.

[0065] Scanning lens 70Y is a lens that images beam BY, reflected by mirror 81Y, onto the surface of photosensitive drum 5AY. Scanning lenses 70Y, 70M, 70C, and 70K refract beams BY, BM, BC, and BK in the sub-scanning direction to image them onto the surface of photosensitive drum 5A. In scanning optical systems Lo1 and Lo2, the sub-scanning direction corresponds to a direction perpendicular to both the main scanning direction and the beam propagation direction.

[0066] Mirror 82M is a mirror that reflects the beam BM, which has passed through the scanning lens 60YM, toward mirror 81M. 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 images the beam BM reflected by the mirror 81M onto the surface of the photosensitive drum 5AM.

[0067] Mirror 82C is a mirror that reflects the beam BC, which has passed through the scanning lens 60CK, toward mirror 81C. 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 images the beam BC reflected by the mirror 81C onto the surface of the photosensitive drum 5AC.

[0068] Mirror 81K is a mirror that reflects the beam BK, which has passed through the scanning lens 60CK, toward the surface of the photosensitive drum 5AK. The scanning lens 70K is a lens that images the beam BK reflected by the mirror 81K onto the surface of the photosensitive drum 5AK.

[0069] As shown in Figure 3, the light emitted from each light source 10Y, 10M, 10C, and 10K is 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 then pass through the corresponding apertures 31Y, 31M, 31C, and 31K of the first aperture wall 30A and are then incident on the focusing lens 40. The beams BY, BM, BC, and BK that have passed through the focusing lens 40 then pass through the corresponding apertures 32A and 32B of the second aperture wall 30B and are incident on the polygon mirror 51.

[0070] As shown in Figure 4, the polygon mirror 51 deflects beams BY, BM, BC, and BK toward the corresponding scanning optical systems Lo1 and Lo2. Beam BY, deflected toward scanning optical system Lo1, passes through scanning lens 60YM, is reflected by mirror 81Y, passes through scanning lens 70Y, and is emitted toward the photosensitive drum 5AY. Beam BY is imaged on the surface of the photosensitive drum 5AY and scanned in the main scanning direction.

[0071] The beam BM, deflected towards the scanning optical system Lo1, passes through scanning lens 60YM, is reflected by mirrors 82M and 81M, passes through scanning lens 70M, and is emitted towards the photosensitive drum 5AM. The beam BM is imaged on the surface of the photosensitive drum 5AM and scanned in the main scanning direction.

[0072] The beam BC, deflected toward the scanning optical system Lo2, passes through the scanning lens 60CK, is reflected by mirrors 82C and 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.

[0073] The beam BK, deflected towards the scanning optical system Lo2, passes through scanning lens 60CK, is reflected by mirror 81K, passes through scanning lens 70K, and is emitted towards the photosensitive drum 5AK. The beam BK is imaged on the surface of the photosensitive drum 5AK and scanned in the main scanning direction.

[0074] As shown in Figure 5, the scanning optical device 4 further comprises an optical sensor 90 and a mirror 85. The polygon mirror 51 rotates counterclockwise in Figure 5.

[0075] The optical sensor 90 is a sensor that detects beams BY and BK that have been deflected by the optical deflector 50 and passed through scanning lenses 60YM and 60CK. More specifically, the optical sensor 90 includes optical sensor 90Y and optical sensor 90K.

[0076] The optical sensor 90Y detects the beam BY that has been deflected by the optical deflector 50 and passed through the scanning lens 60YM. The beam BY detected by the optical sensor 90Y is the 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 (see Figure 4).

[0077] The optical sensor 90K detects the beam BK that has been deflected by the optical deflector 50 and passed through the scanning lens 60CK. The beam BK detected by the optical sensor 90K is the 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 (see Figure 4).

[0078] Mirror 85 is a mirror that reflects beams BY and BK toward the photosensor 90. More specifically, mirror 85 includes mirror 85Y and mirror 85K. Mirror 85Y is deflected by the optical deflector 50 and reflects beam BY, which has passed through the scanning lens 60YM toward the photosensor 90Y. Mirror 85K is deflected by the optical deflector 50 and reflects beam BK, which has passed through the scanning lens 60CK toward the photosensor 90K.

[0079] As shown in Figure 6, the scanning optical device 4 further includes a leaf spring 400. The leaf spring 400 is a component for fixing the scanning lenses 60YM and 60CK to the frame 100. The leaf spring 400 is made of a metal plate. The frame 100 supports the optical deflector 50 and the scanning lenses 60YM and 60CK.

[0080] In this embodiment, the scanning lens 60YM and its periphery, and the scanning lens 60CK and its periphery, have a substantially symmetrical structure with respect to a plane perpendicular to a second direction passing through the rotation axis X1 of the polygon mirror 51. The structure of the scanning lens 60CK and its periphery will be mainly described below.

[0081] As shown in Figure 7, the scanning lens 60CK comprises a lens portion 61 and a flange 62.

[0082] The lens portion 61 is the part that has an optical surface through which the beam passes. More specifically, the lens portion 61 has an incident surface 61A and an exit surface 61B. The incident surface 61A is the surface into which the beam deflected by the optical deflector 50 is incident. The incident surface 61A is a concave surface and is an axially symmetric aspherical surface having axial symmetry with respect to the optical axis of the scanning lenses 60YM and 60CK. The exit surface 61B is the surface from which the beam is emitted. The exit surface 61B is a convex surface and is an axially symmetric aspherical surface having axial symmetry with respect to the optical axis of the scanning lenses 60YM and 60CK.

[0083] The flange 62 is the portion extending in the main scanning direction from the end of the lens portion 61 in the main scanning direction. More specifically, the flange 62 includes a first flange 62A and a second flange 62B. The first flange 62A extends from one end of the lens portion 61 in the main scanning direction toward one side in the main scanning direction. The second flange 62B extends from the other end of the lens portion 61 in the main scanning direction toward the other side in the main scanning direction.

[0084] The frame 100 has a base 120 and a contact wall 130. The base 120 is a platform-shaped portion that supports the scanning lenses 60YM and 60CK. The base 120 protrudes from the frame base wall 110 toward one of the first directions. The base 120 extends in the main scanning direction.

[0085] The base 120 has projections 121 (see also Figure 11). The projections 121 are the parts that the flanges 62 of the scanning lenses 60YM and 60CK contact in a first direction. Specifically, the projections 121 include a first projection 121A and a second projection 121B. The first flange 62A contacts the first projection 121A. The second flange 62B contacts the second projection 121B. Each of the projections 121 (121A, 121B) protrudes from the base 120 in one direction in the first direction.

[0086] The contact wall 130 is the wall to which the flanges 62 of the scanning lenses 60YM and 60CK abut in the second direction. More specifically, the contact wall 130 includes a first contact wall 130A and a second contact wall 130B. The first flange 62A abuts against the first contact wall 130A. The second flange 62B abuts against the second contact wall 130B. The first contact wall 130A and the second contact wall 130B are spaced apart in the main scanning direction.

[0087] Each of the contact walls 130 (130A, 130B) has a wall body 131, a contact rib 132, a projection 133, and a spring guide rib 134. The wall body 131 protrudes from the base 120 in one direction in the first direction. The wall body 131 extends in the main scanning direction.

[0088] The contact rib 132 is the portion that the flange 62 abuts against. The contact rib 132 protrudes inward from the wall body 131 in a second direction. The inward side in the second direction is the side closer to the axis of rotation X1 in that second direction.

[0089] To explain further, the contact rib 132 of the contact wall 130 closer to one of the second directions protrudes from the wall body 131 toward the other of the second directions. Also, the contact rib 132 of the contact wall 130 closer to the other of the second directions protrudes from the wall body 131 toward one of the second directions. For example, the flange 62 of the scanning lens 60CK comes into contact with the contact rib 132 of the contact wall 130 closer to the other of the second directions from one of the second directions.

[0090] The contact rib 132 extends in the first direction. The contact rib 132 of the first contact wall 130A is positioned in the main scanning direction to coincide with the first projection 121A of the base 120. The contact rib 132 of the second contact wall 130B is positioned in the main scanning direction to coincide with the second projection 121B of the base 120.

[0091] The projection 133 protrudes outward from the wall body 131 in a second direction. The outward side in the second direction is the side furthest from the axis of rotation X1 in the second direction. One surface of the projection 133 in the first direction is an inclined surface that slopes from the inside to the outside in the second direction so as it moves toward the other side in the first direction. The other surface of the projection 133 in the first direction is a plane perpendicular to the first direction.

[0092] The spring guide rib 134 is a rib that contacts the leaf spring 400 in the main scanning direction when the leaf spring 400 is attached to the frame 100, and guides the movement of the leaf spring 400. The spring guide rib 134 protrudes outward from the wall body 131 in a second direction. The spring guide rib 134 extends in a first direction.

[0093] The spring guide rib 134 includes a first spring guide rib 134A and a second spring guide rib 134B. The first spring guide rib 134A and the second spring guide rib 134B are spaced apart in the main scanning direction. The first spring guide rib 134A is located on the inside in the main scanning direction. The inside in the main scanning direction is the side closer to the rotation axis X1 in the main scanning direction. The second spring guide rib 134B is located on the outside in the main scanning direction. The outside in the main scanning direction is the side further from the rotation axis X1 in the main scanning direction. The projection 133 is located between the first spring guide rib 134A and the second spring guide rib 134B in the main scanning direction.

[0094] In this embodiment, the second contact wall 130B has a first-direction dimension of the first spring guide rib 134A smaller than the first-direction dimension of the second spring guide rib 134B. Furthermore, the wall body 131 of the second contact wall 130B has a shape that is such that one side of the first spring guide rib 134A in the first direction is cut out compared to the wall body 131 of the first contact wall 130A. This prevents the beams BY and BK (see Figure 5), which are deflected by the optical deflector 50 and directed toward the optical sensor 90, from interfering with the second contact wall 130B.

[0095] As shown in Figure 8, the contact wall 130 (130A, 130B) is further from the rotation axis X1 of the polygon mirror 51 than the flange 62 is in the second direction. In other words, the flange 62 is located between the contact wall 130 (130A, 130B) and the rotation axis X1 in the second direction. Furthermore, the flange 62 is located between the contact wall 130 (130A, 130B) and the polygon mirror 51 in the second direction.

[0096] As shown in Figures 8 and 9(a) and 9(b), the leaf spring 400 has a base 410, a first arm 420, and a second arm 430.

[0097] The base 410 is the portion that contacts the contact wall 130 from the opposite side of the flange 62 in the second direction. The base 410 has a through hole 411. The through hole 411 penetrates in the second direction. The through hole 411 engages with the projection 133 of the contact wall 130 when the leaf spring 400 is attached to the frame 100 and the scanning lenses 60YM and 60CK are fixed to the frame 100 (see Figure 6). The engagement of the through hole 411 of the base 410 with the projection 133 prevents the leaf spring 400 from coming off the frame 100.

[0098] The first arm 420 is the portion that sandwiches the contact wall 130 and the flange 62 between itself and the base 410. The first arm 420 biases the flange 62 toward the contact wall 130. The first arm 420 extends from one end of the base 410 in a first direction. Specifically, the first arm 420 has two arm portions 421 and a connecting portion 422.

[0099] The two arm portions 421 are spaced apart in the main scanning direction. The arm portions 421 sandwich the contact wall 130 and flange 62 between themselves and the base 410. Each arm portion 421 extends from one end of the base 410 in the first direction. More specifically, the arm portion 421 extends from one end of the base 410 in the first direction toward one side of the first direction, bends inward toward the second direction to straddle the contact wall 130 and flange 62, and then bends further toward the other side of the first direction.

[0100] The connecting portion 422 extends in the main scanning direction and connects the two arm portions 421. More specifically, the connecting portion 422 connects the end of one arm portion 421 that is farther from the base 410 to the end of the other arm portion 421 that is farther from the base 410.

[0101] The second arm 430 is positioned between the two arm portions 421 in the main scanning direction. The second arm 430 extends from one end of the base 410 in the first direction. More specifically, the second arm 430 extends from one end of the base 410 in the first direction toward one side of the first direction, then bends toward the inside in the second direction. The second arm 430 contacts one end of the flange 62 in the first direction and biases the flange 62 toward the other side of the first direction.

[0102] As shown in Figure 6, the leaf spring 400 includes a first leaf spring 400A and a second leaf spring 400B. The first leaf spring 400A sandwiches the first contact wall 130A and the first flange 62A. The second leaf spring 400B sandwiches the second contact wall 130B and the second flange 62B. The first leaf spring 400A and the second leaf spring 400B are parts of the same shape.

[0103] In this embodiment, the scanning optical device 4 comprises two first leaf springs 400A and two second leaf springs 400B. More specifically, the scanning optical device 4 comprises the first leaf springs 400A and the second leaf springs 400B for fixing the scanning lens 60YM to the frame 100, and the first leaf springs 400A and the second leaf springs 400B for fixing the scanning lens 60CK to the frame 100.

[0104] As shown in Figure 10, the first leaf spring 400A and the second leaf spring 400B do not overlap with the optical deflector 50 when viewed from the first direction. More specifically, the first leaf spring 400A and the second leaf spring 400B do not overlap with the substrate 53 of the optical deflector 50 when viewed from the first direction. In other words, the first leaf spring 400A and the second leaf spring 400B are located outside the substrate 53 in the second direction.

[0105] Furthermore, the first leaf spring 400A and the second leaf spring 400B are each located between one end 53A and the other end 53B of the substrate 53 in the main scanning direction. In other words, the first leaf spring 400A and the second leaf spring 400B are each located within the width of the substrate 53 in the main scanning direction (between the two dashed lines shown in Figure 10).

[0106] As shown in Figure 11, the frame 100 further includes a partition wall 140 and a plurality of substrate guide ribs 150. In this embodiment, the substrate guide ribs 150 correspond to "ribs".

[0107] The partition wall 140 is a wall that protrudes from the frame base wall 110 in one direction in the first direction. The partition wall 140 extends in the main scanning direction. One end of the partition wall 140 in the main scanning direction is connected to the base 120. The other end of the partition wall 140 in the main scanning direction is connected to the second aperture wall 30B. The partition wall 140 protrudes beyond the base 120 in one direction in the first direction.

[0108] The substrate guide rib 150 is a rib that extends in a first direction. Multiple substrate guide ribs 150 are aligned in the main scanning direction. Specifically, the substrate guide rib 150 includes a first substrate guide rib 151, a second substrate guide rib 152, and a third substrate guide rib 153.

[0109] The second substrate guide rib 152 and the third substrate guide rib 153 protrude inward from the partition wall 140 in the second direction. The second substrate guide rib 152 is located at one end of the partition wall 140 in the main scanning direction. The third substrate guide rib 153 is located on the other side of the second substrate guide rib 152 in the main scanning direction, spaced apart from the second substrate guide rib 152 in the main scanning direction.

[0110] The first substrate guide rib 151 protrudes inward from the base 120 in a second direction. The dimension of the first substrate guide rib 151 in the first direction is smaller than the dimension of the second substrate guide rib 152 in the first direction. The dimension of the first substrate guide rib 151 in the first direction is smaller than the dimension of the third substrate guide rib 153 in the first direction. The dimension of the first substrate guide rib 151 in the first direction is approximately the same as the dimension of the base 120 in the first direction.

[0111] The first substrate guide rib 151 is positioned at a distance from the second substrate guide rib 152 in the main scanning direction, and is located on one side of the second substrate guide rib 152 in the main scanning direction. The position of the first substrate guide rib 151 in the main scanning direction coincides with the first contact wall 130A. In addition, a portion of the first substrate guide rib 151 is positioned in the main scanning direction to coincide with the contact rib 132 of the first contact wall 130A and the first projection 121A of the base 120.

[0112] As shown in Figure 10, the frame 100 has a plurality of such substrate guide ribs 150 (151-153) on both sides of the substrate 53 in the second direction (see also Figure 7). The substrate guide ribs 150 (151-153) contact the substrate 53 of the optical deflector 50 in the second direction when the optical deflector 50 is attached to the frame 100, and guide the movement of the substrate 53.

[0113] Next, the effects of the embodiment will be described. Because the contact wall 130 of the frame 100 is further from the rotation axis X1 of the polygon mirror 51 than the flange 62 of the scanning lenses 60YM, 60CK in the second direction, the distance between the polygon mirror 51 and the contact wall 130 can be maintained even if the distance between the polygon mirror 51 and the scanning lenses 60YM, 60CK is reduced. This makes it possible to suppress interference between the leaf spring 400 and the polygon mirror 51 when, for example, the leaf spring 400 is attached to the frame 100.

[0114] The first arm 420 has two arm portions 421, which ensures the load when the flange 62 is biased toward the contact wall 130.

[0115] The first arm 420 has a connecting portion 422 that connects two arm portions 421, so that when attaching the leaf spring 400 to the frame 100, the first arm 420 with the two arm portions 421 can be operated as a single unit. This makes it easier to attach the leaf spring 400 to the frame 100.

[0116] The leaf spring 400 has a first arm 420 and a second arm 430, so that one leaf spring 400 can bias the flange 62 toward the contact wall 130 in a second direction, and also bias the flange 62 in a first direction.

[0117] By ensuring that the leaf spring 400 does not overlap with the substrate 53 of the optical deflector 50 when viewed from the first direction, interference between the leaf spring 400 and the optical deflector 50 can be suppressed when the leaf spring 400 and the optical deflector 50 are mounted on the frame 100 along the first direction.

[0118] By positioning the first leaf spring 400A and the second leaf spring 400B between one end 53A and the other end 53B of the substrate 53 in the main scanning direction, the scanning lenses 60YM, 60CK, the first leaf spring 400A, the second leaf spring 400B, and the optical deflector 50 can be compactly arranged in the main scanning direction.

[0119] The frame 100 has a plurality of substrate guide ribs 150 (151-153) that guide the movement of the substrate 53 when the optical deflector 50 is attached to the frame 100, thereby preventing the optical deflector 50 from interfering with the leaf spring 400 when the optical deflector 50 is attached to the frame 100.

[0120] The frame 100 has multiple substrate guide ribs 150 (151-153) on both sides of the substrate 53 in the second direction, which further suppresses interference between the optical deflector 50 and the leaf spring 400 when the optical deflector 50 is attached to the frame 100.

[0121] Because the incident surfaces 61A of the scanning lenses 60YM and 60CK are concave, even when the distance between the polygon mirror 51 and the scanning lenses 60YM and 60CK is reduced, space can be secured between the polygon mirror 51 and the incident surfaces 61A of the scanning lenses 60YM and 60CK. This makes it possible to suppress noise generation caused by airflow generated as the polygon mirror 51 rotates, for example.

[0122] Although embodiments have been described above, the scanning optical device can be modified as appropriate, as illustrated below.

[0123] In the embodiment, as shown in Figure 10, both the first leaf spring 400A and the second leaf spring 400B were located between one end 53A and the other end 53B of the substrate 53 in the main scanning direction. However, for example, only one of the first and second leaf springs may be located between one end and the other end of the substrate in the main scanning direction. In other words, part or all of the other of the first and second leaf springs may be located outside the edge of the substrate in the main scanning direction. Alternatively, part or all of both the first and second leaf springs may be located outside the edge of the substrate in the main scanning direction.

[0124] In this embodiment, the frame 100 had multiple substrate guide ribs 150 (151-153) as ribs on both sides of the substrate 53 of the optical deflector 50 in the second direction. However, for example, the frame may have multiple ribs on only one side of the substrate in the second direction. Also, for example, the frame may not have ribs to guide the movement of the substrate when the optical deflector is attached to the frame.

[0125] In this embodiment, the scanning optical device 4 had a flange 62, a contact wall 130, and a leaf spring 400 on both sides of the scanning lenses 60YM and 60CK in the main scanning direction, respectively. However, for example, the scanning optical device may have a flange, a contact wall, and a leaf spring on only one side of the scanning lens in the main scanning direction.

[0126] In this embodiment, the leaf spring 400 did not overlap with the substrate 53 of the optical deflector 50 when viewed from the first direction, but for example, the leaf spring may overlap with the substrate when viewed from the first direction. Also, in this embodiment, the leaf spring 400 had a second arm 430, but for example, the leaf spring may not have a second arm.

[0127] In the embodiment, the first arm 420 of the leaf spring 400 had a connecting portion 422 that connected two arm portions 421, but for example, the first arm does not have to have a connecting portion. Also, in the embodiment, the first arm 420 had two arm portions 421, but for example, the first arm may have only one arm portion.

[0128] In the embodiment, the scanning optical device 4 was equipped with multiple light source devices LM1, LM2 and scanning lenses 60YM, 60CK, but for example, there may be only one light source device or one scanning lens. Also, in the embodiment, the scanning optical device 4 was a scanning optical device used in an image forming apparatus 1 such as a laser printer, but for example, the scanning optical device may be a scanning optical device used in an apparatus other than an image forming apparatus.

[0129] The elements described in the embodiments and modifications may be implemented in any combination. [Explanation of Symbols]

[0130] 4. Scanning Optical Device 5A Photosensitive Drum 50 optical deflector 51 Polygon Mirror 60YM, 60CK scanning lens 61 Lens section 62 Flange 100 frames 130 Abutment wall 400 leaf springs 410 Base 420 First Arm BY, BM, BC, BK Beam LM1,LM2 Light source device Lo1, Lo2 scanning optical system X1 Rotation axis

Claims

1. A light source device that emits a beam, An optical deflector for deflecting a beam in the main scanning direction, comprising an optical deflector having a polygon mirror rotatable about a rotation axis extending in a first direction perpendicular to the main scanning direction, A scanning optical system for imaging a beam deflected by the optical deflector onto a scanning surface, comprising a scanning optical system having a scanning lens into which the beam deflected by the optical deflector is incident, A frame supporting the optical deflector and the scanning lens, The scanning lens is fixed to the frame by a leaf spring, The scanning lens is The lens part, The lens portion comprises a flange extending from the end in the main scanning direction, The frame has a contact wall against which the flange abuts in a second direction perpendicular to both the main scanning direction and the first direction, and the contact wall is further from the rotation axis than the flange in the second direction. The aforementioned leaf spring is A base that contacts the contact wall from the opposite side of the flange in the second direction, A scanning optical apparatus characterized by having a first arm extending from one end of the base in the first direction and sandwiching the contact wall and the flange between itself and the base, the first arm biasing the flange toward the contact wall.

2. The scanning optical apparatus according to claim 1, wherein the first arm has two arm portions that extend from one end of the base in a first direction and sandwich the contact wall and the flange between itself and the base, and the two arm portions are spaced apart in the main scanning direction.

3. The scanning optical apparatus according to claim 2, characterized in that the first arm has a connecting portion extending in the main scanning direction, which connects the end of one arm portion furthest from the base with the end of the other arm portion furthest from the base.

4. The scanning optical apparatus according to claim 2 or 3, characterized in that the leaf spring has a second arm extending from one end of the base in the first direction, which is located between the two arm portions in the main scanning direction and contacts one end of the flange in the first direction to bias the flange toward the other end in the first direction.

5. The optical deflector has a substrate that supports the polygon mirror, The scanning optical apparatus according to claim 1, characterized in that the leaf spring does not overlap with the substrate when viewed from the first direction.

6. The aforementioned flange is A first flange extending from one end of the lens portion in the main scanning direction, The lens portion includes a second flange extending from the other end in the main scanning direction, The aforementioned contact wall is The first contact wall against which the first flange abuts, The second flange includes a second contact wall with which it abuts, The aforementioned leaf spring is A first leaf spring sandwiching the first contact wall and the first flange, The second contact wall and the second flange are sandwiched together by a second leaf spring, The scanning optical apparatus according to claim 5, characterized in that at least one of the first leaf spring and the second leaf spring is located between one end and the other end of the substrate in the main scanning direction.

7. The scanning optical apparatus according to claim 5 or 6, wherein the frame is a plurality of ribs extending in the first direction and a plurality of ribs aligned in the main scanning direction, the ribs having contact with the substrate in the second direction when the optical deflector is attached to the frame and guiding the movement of the substrate.

8. The scanning optical apparatus according to claim 7, characterized in that the frame has the plurality of ribs on both sides of the substrate in the second direction.

9. The scanning lens has an incident surface to which the beam deflected by the optical deflector is incident, The scanning optical apparatus according to claim 1, characterized in that the incident surface is a concave surface.

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