Scanning Optical Device

Abstract

To relax the constraints on the structure of a facility to adjust a coupling lens.SOLUTION: A scanning optical device 1 comprises: a semiconductor laser 10 that emits light; a coupling lens 20 that converts the light from the semiconductor laser 10 into a beam; a deflector 50 that has a polygon mirror 51 deflecting the beam from the coupling lens 20; a scanning optical system Lo that forms the beam deflected by the deflector 50 into an image on an image surface; and a frame F to which the deflector 50 is fixed. The frame F has a first base wall Fb1 that intersects a first direction along the axis of rotation X1 of the polygon mirror 51 and is attached with the deflector 50, and a second base wall Fb2 that intersects the first direction and is located at a position shifted with respect to the first base wall Fb1 on one side in the first direction. The deflector 50 is located on one side in the first direction with respect to the first base wall Fb1. The coupling lens 20 is on the other side in the first direction with respect to the second base wall Fb2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a scanning optical device including a coupling lens and a deflector. [Background technology]

[0002] Conventionally, a known scanning optical device includes a coupling lens that converts light from a semiconductor laser into a beam, a deflector having a polygon mirror that deflects the beam from the coupling lens, a scanning optical system that focuses the beam deflected by the deflector on an image plane, and a frame that holds the coupling lens, deflector, and scanning optical system (see Patent Document 1). In this technology, the frame has a first recess that opens toward one side of the rotation axis direction of the polygon mirror and a second recess that opens toward the other side of the rotation axis direction. The coupling lens and deflector are disposed in the first recess, and the scanning optical system is disposed in the second recess. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-206910 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional technology, the device for adjusting the position of the coupling lens and the device for detecting the light incident on the polygon mirror must be placed within the first recess, i.e., on the same side of the frame, which creates a problem of restrictions on the structure of the equipment.

[0005] Therefore, an object of the present invention is to alleviate the constraints on the structure of equipment for adjusting coupling lenses and the like. [Means for solving the problem]

[0006] In order to solve the above problem, the scanning optical device of the present invention comprises a semiconductor laser that emits light, a coupling lens that converts the light from the semiconductor laser into a beam, a deflector having a polygon mirror that deflects the beam from the coupling lens, a scanning optical system that focuses the beam deflected by the deflector on an image plane, and a frame to which the deflector is fixed. The frame has a first base wall that intersects a first direction along the rotation axis of the polygon mirror and to which the deflector is attached, and a second base wall that intersects the first direction and is positioned offset to one side of the first direction relative to the first base wall. The deflector is located on one side of the first base wall in the first direction. The coupling lens is located on the other side in the first direction with respect to the second base wall.

[0007] With this configuration, the device for adjusting the position of the coupling lens can be placed on the other side of the frame in the first direction, and the device for detecting light incident on the polygon mirror can be placed on one side of the frame in the first direction, thereby easing constraints on the structure of the equipment.

[0008] At least a part of the scanning optical system may be attached to one side of the first base wall in the first direction.

[0009] According to this configuration, the deflector and the scanning optical system are mounted in the same direction, so that the scanning optical system can be positioned with high precision.

[0010] The beam from the scanning optical system may be emitted toward an image plane on one side in the first direction.

[0011] According to this configuration, the beam emitted from the scanning optical system can be measured from the opposite side to the device for adjusting the position of the coupling lens.

[0012] The scanning optical system may include a reflecting mirror that reflects the beam toward an image plane, and the reflecting mirror may be exposed on the other side in the first direction with respect to the first base wall.

[0013] According to this configuration, the reflecting mirror is exposed on the other side in the first direction relative to the first base wall, so that the coupling lens and the reflecting mirror that need to be adjusted can be adjusted from the same side.

[0014] The scanning optical device may further include a first cover that covers the deflector and the first base wall from one side in the first direction.

[0015] According to this configuration, the first cover can prevent dust from adhering to the deflector.

[0016] The scanning optical device may further include a second cover that covers the coupling lens and the second base wall from the other side in the first direction.

[0017] According to this configuration, the second cover can prevent dust from adhering to the coupling lens.

[0018] Furthermore, the scanning optical system may be arranged on one side of the polygon mirror in a second direction perpendicular to the first direction, and a beam deflected in a main scanning direction perpendicular to the first direction and the second direction may be incident thereon, and the scanning optical device may further include a first screw and a second screw that fix the first cover to the frame, and the rotation axis may be located between the first screw and the second screw in the main scanning direction.

[0019] According to this configuration, the sealing performance provided by the first cover can be improved.

[0020] The scanning optical device may have a plurality of the semiconductor lasers and the coupling lenses, and two of the beams emitted from the plurality of coupling lenses may be spaced apart in the second direction, and the first screw may be located between the optical paths of the two beams. [Effects of the Invention]

[0021] According to the present invention, it is possible to ease the constraints on the structure of equipment for adjusting the coupling lens, etc. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 2 is a perspective view of the scanning optical device according to the embodiment, as viewed from the other side in the first direction. [Figure 2] FIG. 2 is a perspective view showing the structure around the coupling lens. [Figure 3] FIG. 2 is a perspective view of the scanning optical device as seen from one side in a first direction. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. [Figure 5] FIG. 2 is a cross-sectional view of FIG. 1 . [Figure 6] FIG. 2 is a perspective view of the frame as seen from the other side in the first direction. [Figure 7] FIG. 2 is a perspective view of the frame as seen from one side in the first direction. [Figure 8] FIG. 10 is a cross-sectional view showing a structure for attaching the reflecting mirror to the frame. [Figure 9] FIG. 2 is an exploded perspective view showing a frame, a first cover, and a second cover. [Figure 10] FIG. 2 is a plan view of the frame as seen from one side in the first direction. [Figure 11] 1 is a plan view of a frame to which a first cover is attached, viewed from one side in a first direction. [Figure 12] FIG. 4 is a cross-sectional view showing a second rib of the first cover. [Figure 13] FIG. 4 is a cross-sectional view showing a seal member between a first cover and a first scanning lens. [Figure 14]FIG. 2 is a perspective view of a second cover as viewed from one side in a first direction. [Figure 15] 4 is a cross-sectional view showing the relationship between the first wall and the first rib of the second cover. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0023] As shown in FIGS. 1 to 3, the scanning optical device 1 includes a frame F, an incident optical system Li, a deflector 50, and a scanning optical system Lo. The scanning optical device 1 is applied to an electrophotographic image forming apparatus. In the following description, a direction along the rotation axis X1 of the polygon mirror 51 shown in FIG. 3 is referred to as a "first direction." A direction perpendicular to the first direction, in which the polygon mirror 51 and the first scanning lens 60 shown in FIG. 3 are aligned, is referred to as a "second direction." A direction perpendicular to the first and second directions is referred to as a "third direction." In the scanning optical system Lo, the third direction corresponds to the main scanning direction, and the first direction corresponds to the sub-scanning direction. In the drawings, arrows indicating each direction indicate "one side" in each direction.

[0024] As shown in FIG. 2, the incident optical system Li includes four semiconductor lasers 10, four coupling lenses 20, an aperture plate 30, and a condenser lens 40 (see FIG. 1).

[0025] The semiconductor laser 10 is a device that emits light. Four semiconductor lasers 10 are provided corresponding to four photosensitive drums 200 (see FIG. 5) that are scanned and exposed by the scanning optical device 1. A toner image of a different color is formed on each photosensitive drum 200.

[0026] In this embodiment, the first color is "yellow (Y)," the second color is "magenta (M)," the third color is "cyan (C)," and the fourth color is "black (K)." In the following description, the names of components corresponding to the first color may be distinguished by adding "first" to the beginning of the name and adding "Y" to the end of the reference numerals of the components corresponding to the first color. Similarly, the names of components corresponding to the second, third, and fourth colors may be distinguished by adding "second," "third," and "fourth" to the beginning of the name and adding "M," "C," and "K" to the end of the reference numerals.

[0027] The first semiconductor laser 10Y is arranged in the first direction with a gap between them and the second semiconductor laser 10M. The first semiconductor laser 10Y is located on one side in the first direction with respect to the second semiconductor laser 10M.

[0028] The third semiconductor laser 10C is arranged adjacent to the second semiconductor laser 10M in the second direction at a distance. The third semiconductor laser 10C is located on the other side in the second direction relative to the second semiconductor laser 10M. The fourth semiconductor laser 10K is arranged adjacent to the third semiconductor laser 10C in the first direction at a distance, and is arranged adjacent to the first semiconductor laser 10Y in the second direction at a distance.

[0029] The coupling lens 20 is a lens that converts the light from the semiconductor laser 10 into a beam. The coupling lenses 20Y, 20M, 20C, and 20K corresponding to each color are arranged at positions facing the corresponding semiconductor lasers 10Y, 10M, 10C, and 10K.

[0030] 1, the diaphragm plate 30 is a portion having an aperture diaphragm 31 through which the beam from the coupling lens 20 passes, and is formed integrally with the frame F. The diaphragm plate 30 is located between the coupling lens 20 and the condenser lens 40.

[0031] The condenser lens 40 is a lens that condenses the beam from the coupling lens 20 onto the polygon mirror 51 in the sub-scanning direction. The condenser lens 40 is located on the opposite side of the diaphragm plate 30 from the coupling lens 20.

[0032] As shown in FIG. 3, the deflector 50 has a polygon mirror 51 and a motor 52. The polygon mirror 51 is a mirror that deflects the beam from the condenser lens 40 in the main scanning direction. The polygon mirror 51 has five mirror surfaces that are equidistant from the rotation axis X1. The motor 52 is a motor that rotates the polygon mirror 51. The motor 52 is fixed to the frame F.

[0033] The scanning optical system Lo is an optical system that forms an image of the beam deflected by the deflector 50 on the surface of the photosensitive drum 200, which serves as an image plane. The scanning optical system Lo is fixed to a frame F. As shown in FIG. 5, the scanning optical system Lo has a first scanning optical system LoY corresponding to yellow, a second scanning optical system LoM corresponding to magenta, a third scanning optical system LoC corresponding to cyan, and a fourth scanning optical system LoK corresponding to black.

[0034] The first scanning optical system LoY and the second scanning optical system LoM are arranged on one side of the polygon mirror 51 in the second direction. The third scanning optical system LoC and the fourth scanning optical system LoK are arranged on the other side of the polygon mirror 51 in the second direction. A beam deflected in the main scanning direction by the polygon mirror 51 is incident on each of the scanning optical systems LoY, LoM, LoC, and LoK.

[0035] The first scanning optical system LoY has a first scanning lens 60YM, a second scanning lens 70Y, and a reflecting mirror 81Y.

[0036] The first scanning lens 60YM is a lens that refracts the beams BY and BM deflected by the deflector 50 in the main scanning direction to form an image on the image plane. The first scanning lens 60YM also has an fθ characteristic that causes the light scanned at a constant angular velocity by the deflector 50 to move at a constant velocity on the image plane. The first scanning lens 60YM is the scanning lens closest to the polygon mirror 51 in the first scanning optical system LoY.

[0037] The reflecting mirror 81Y is a mirror that reflects the beam BY from the first scanning lens 60YM toward the image plane. The second scanning lens 70Y is a lens that refracts the beam BY reflected by the reflecting mirror 81Y in the sub-scanning direction to form an image on the image plane. The second scanning lens 70Y is disposed on one side of the polygon mirror 51 in the first direction. The second scanning lens 70Y is the scanning lens in the first scanning optical system LoY that is closest to the image plane.

[0038] The second scanning optical system LoM has a first scanning lens 60YM, a second scanning lens 70M, a reflecting mirror 81M, and a mirror 82M.

[0039] The first scanning lens 60YM is shared with the first scanning optical system LoY. The second scanning lens 70M and the reflecting mirror 81M have the same functions as the second scanning lens 70Y and the reflecting mirror 81Y of the first scanning optical system LoY. The mirror 82M reflects the beam BM from the first scanning lens 60YM to the reflecting mirror 81M.

[0040] The third scanning optical system LoC has a structure that is generally symmetrical to the second scanning optical system LoM with respect to the rotation axis X1 of the polygon mirror 51. Specifically, the third scanning optical system LoC has a first scanning lens 60CK, a second scanning lens 70C, a reflecting mirror 81C, and a mirror 82C that have the same functions as the respective components of the second scanning optical system LoM.

[0041] The fourth scanning optical system LoK has a structure that is generally symmetrical to the first scanning optical system LoY with respect to the rotation axis X1 of the polygon mirror 51. Specifically, the fourth scanning optical system LoK has a first scanning lens 60CK, a second scanning lens 70K, and a reflecting mirror 81K that have the same functions as the respective components of the first scanning optical system LoY.

[0042] 4, the light emitted from each semiconductor laser 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. After passing through the corresponding aperture stops 31Y, 31M, 31C, and 31K of the diaphragm plate 30, the beams BY, BM, BC, and BK pass through the condenser lens 40 and are then incident on the polygon mirror 51. The condenser lens 40 is a lens through which all of the beams BY, BM, BC, and BK pass, and has a cylindrical entrance surface and a flat exit surface.

[0043] As shown in Fig. 5, the polygon mirror 51 deflects the beams BY, BM, BC, and BK toward the corresponding scanning optical systems LoY, LoM, LoC, and LoK. The beam BY toward the first scanning optical system LoY passes through the first scanning lens 60YM, is reflected by the reflecting mirror 81Y, and passes through the second scanning lens 70Y to be emitted toward an image plane on one side in the first direction. The beam BY is emitted from the second scanning lens 70Y at a predetermined angle with respect to the first direction. The beam BY is imaged on the surface of the first photosensitive drum 200Y and is scanned in the main scanning direction.

[0044] The beam BM heading toward the second scanning optical system LoM passes through the first scanning lens 60YM, is reflected by the mirror 82M and the reflecting mirror 81M, and passes through the second scanning lens 70M to be emitted toward an image plane on one side in the first direction. The beam BM is emitted from the second scanning lens 70M at a predetermined angle with respect to the first direction. The beam BM is imaged on the surface of the second photosensitive drum 200M and scanned in the main scanning direction. Similarly, the beams BC and BK are also emitted toward an image plane on one side in the first direction by the corresponding scanning optical systems LoC and LoK, are imaged on the surfaces of the corresponding photosensitive drums 200C and 200K, and are scanned in the main scanning direction.

[0045] The frame F is made of resin and is integrally formed by molding. The frame F has a first recess CP1 shown in FIG. 7 and a second recess CP2 shown in FIG. 6. The first recess CP1 opens to one side in the first direction. The second recess CP2 opens to the other side in the first direction. As shown in FIG. 5, a deflector 50 and a part of the scanning optical system Lo are disposed in the first recess CP1. Specifically, the components of the scanning optical system Lo except for the reflecting mirrors 81 are disposed in the first recess CP1. As shown in FIG. 2, a coupling lens 20, an aperture plate 30, and a condenser lens 40 (see FIG. 1) are disposed in the second recess CP2.

[0046] As shown in FIGS. 6 and 7, the frame F has a first base wall Fb1 located at the bottom of the first recess CP1 and a second base wall Fb2 located at the bottom of the second recess CP2.

[0047] The first base wall Fb1 and the second base wall Fb2 are walls that intersect with the first direction. More specifically, the first base wall Fb1 and the second base wall Fb2 are walls whose thickness directions are aligned with the first direction. In other words, the first base wall Fb1 and the second base wall Fb2 are walls having planes that are perpendicular to the first direction.

[0048] The second base wall Fb2 is positioned offset to one side in the first direction with respect to the first base wall Fb1. As shown in FIG. 5, the deflector 50 is attached to the first base wall Fb1. Specifically, a circuit board constituting the motor 52 is fixed to the first base wall Fb1 with screws from one side in the first direction. Furthermore, the aforementioned part of the scanning optical system Lo is attached to the first base wall Fb1 on one side in the first direction. Specifically, as shown in FIG. 7, the first scanning lenses 60YM and 60CK are attached to a first seating surface B1, which is a part of the first base wall Fb1. The first seating surface B1 is a surface offset to one side in the first direction from the part of the first base wall Fb1 where the deflector 50 is attached. Furthermore, the second scanning lenses 70Y, 70M, 70C, and 70K are attached to a second seating surface B2 protruding from the first base wall Fb1 on one side in the first direction. The mirrors 82M and 82C are attached to a third seating surface B3 that protrudes from the first base wall Fb1 to one side in the first direction. The portion of the first base wall Fb1 that overlaps with the mirrors 82M and 82C in the first direction is a surface that is shifted toward one side in the first direction from the portion of the first base wall Fb1 where the deflector 50 is attached. Therefore, the deflector 50 and a portion of the scanning optical system Lo are located on one side in the first direction relative to the first base wall Fb1. As shown in FIG. 2, the semiconductor laser 10, the coupling lens 20, and the diaphragm plate 30 are located on the other side in the first direction relative to the second base wall Fb2. Also, as shown in FIG. 1, the condenser lens 40 and the reflecting mirror 81 are located on the other side in the first direction relative to the second base wall Fb2.

[0049] The reflecting mirror 81 is disposed near the first base wall Fb1 and is exposed on the other side in the first direction relative to the first base wall Fb1. In other words, the first base wall Fb1 does not have a portion located on the other side in the first direction of the reflecting mirror 81. As a result, the reflecting mirror 81 is exposed on the other side in the first direction without being hidden by the first base wall Fb1, and can be attached to the frame F from the other side in the first direction.

[0050] As shown in Fig. 6, the frame F further has a first wall F1 located between the first recess CP1 and the second recess CP2. The first wall F1 is connected to the first base wall Fb1 and the second base wall Fb2 (see also Fig. 7). The first wall F1 protrudes from the second base wall Fb2 to the other side in the first direction and protrudes from the first base wall Fb1 to one side in the first direction.

[0051] The first wall F1 has two first openings F11 and F12 through which the beams BY, BM, BC, and BK pass from the aperture stops 31 of the diaphragm plate 30 toward the polygon mirror 51. The first openings F11 and F12 are formed in the shape of slits that are long in the first direction, penetrate in the third direction, and open to one side in the first direction (see FIG. 7). The first opening F11 passes the beams BY and BM. The first opening F12 passes the beams BC and BK.

[0052] As shown in FIG. 1, the condenser lens 40 is disposed so as to block the first openings F11 and F12 shown in FIG. 6. The condenser lens 40 is sandwiched between the first wall F1 and the diaphragm plate 30. As shown in FIG. 15, the condenser lens 40 has a rib 40A protruding from the exit surface toward one side in the third direction, and the rib 40A is in contact with the first wall F1. The condenser lens 40 also has a rib 40B protruding from the incident surface toward the other side in the third direction, and the rib 40B is in contact with the diaphragm plate 30. More specifically, each end of the rib 40B in the second direction is in contact with the diaphragm plate 30 (see FIG. 1). The ribs 40A and 40B are configured to surround the peripheries of the exit surface and the incident surface, which are optical surfaces of the condenser lens 40. This allows the condenser lens 40 to block the first openings F11 and F12 without the optical surfaces of the condenser lens 40 directly contacting the first wall F1 and the diaphragm plate 30.

[0053] 3 and 7, the frame F further has two second walls F2 located on either side of the polygon mirror 51 (see FIG. 3) in the second direction. The second wall F2 on one side in the second direction has a second opening F21 through which the beams BY and BM reflected by the polygon mirror 51 pass. The second wall F2 on the other side in the second direction has a second opening F22 through which the beams BC and BK reflected by the polygon mirror 51 pass. Each of the second openings F21 and F22 penetrates in the second direction and opens to one side in the first direction.

[0054] Each second wall F2 protrudes from the first base wall Fb1 to one side in the first direction. Each second wall F2 is connected to the first wall F1 and a first side wall F41 (described later). As a result, the first base wall Fb1, the first wall F1, each second wall F2, and the first side wall F41 form an accommodating recess CP3 for accommodating the polygon mirror 51.

[0055] The first scanning lens 60YM is disposed so as to block a portion of the second opening F21, and the first scanning lens 60CK is disposed so as to block a portion of the second opening F22.

[0056] The frame F further has a first side wall F41, a second side wall F42, a third side wall F43, and a fourth side wall F44 that form a substantially rectangular frame surrounding each of the recesses CP1 and CP2.

[0057] The first side wall F41 is located on the opposite side of the deflector 50 from the semiconductor laser 10. The first side wall F41 protrudes from the first base wall Fb1 to one side in the first direction.

[0058] The second side wall F42 is located on the opposite side of the deflector 50 from the first side wall F41. More specifically, the second side wall F42 is located on the opposite side of the coupling lens 20 from the deflector 50. The second side wall F42 protrudes from the second base wall Fb2 to the other side in the first direction.

[0059] The third side wall F43 is located on the opposite side of the first scanning lens 60YM from the deflector 50. The third side wall F43 is connected to one end of the first side wall F41, the first base wall Fb1, the second base wall Fb2, and the second side wall F42 in the second direction. A part of the third side wall F43 protrudes from the first base wall Fb1 to one side in the first direction, and another part protrudes from the second base wall Fb2 to the other side in the first direction.

[0060] The fourth side wall F44 is located on the opposite side of the deflector 50 with respect to the first scanning lens 60CK. The fourth side wall F44 is connected to the other end portions in the second direction of the first side wall F41, the first base wall Fb1, the second base wall Fb2, and the second side wall F42. A part of the fourth side wall F44 protrudes from the first base wall Fb1 to one side in the first direction, and another part protrudes from the second base wall Fb2 to the other side in the first direction.

[0061] As shown in FIG. 8, the scanning optical device 1 further includes a support member Fs that is detachable from the frame F, which includes the first recess CP1 and the second recess CP2 described above. The support member Fs supports the reflecting mirror 81. The support member Fs has a seat FsZ that supports the reflecting mirror 81 and allows the angle to be adjusted. The seat FsZ has a spherical protrusion Fs1 that can tiltably support the reflecting mirror 81. The protrusion Fs1 protrudes toward the reflecting mirror 81 and comes into contact with the reflecting mirror 81 to serve as a fulcrum when adjusting the orientation of the reflecting mirror 81. The orientation of the reflecting mirror 81 relative to the seat FsZ is fixed by a photocurable resin P. The photocurable resin P can be, for example, an ultraviolet-curable resin. The reflecting mirror 81 and the support member Fs, which are fixed by the photocurable resin P, are attached to the frame F by a U-shaped leaf spring SP.

[0062] For each reflecting mirror 81, one support member Fs and one leaf spring SP are arranged at each longitudinal end of the reflecting mirror 81. A pair of support members Fs and a pair of leaf springs SP corresponding to one reflecting mirror 81 are provided for each of the four reflecting mirrors 81.

[0063] The frame F has a support surface Fm1 that supports the support member Fs. The support surfaces Fm1 are disposed at positions corresponding to the longitudinal ends of the four reflecting mirrors 81 (see FIG. 6).

[0064] When attaching the reflecting mirror 81 to the frame F, photocurable resin P is applied to both sides of the protrusion Fs1 of the support member Fs, and the support member Fs is attached to the support surface Fm1. Then, the first reflecting mirror 81 is brought into contact with the protrusion Fs1 of the support member Fs. At this time, the photocurable resin P is placed in contact with both the support member Fs and the first reflecting mirror 81. Then, a leaf spring SP is attached, and the first reflecting mirror 81 and the support member Fs are pressed toward the frame F. Next, with light emitted from the semiconductor laser 10, the first reflecting mirror 81 is tilted from the protrusion Fs1 as a starting point, thereby adjusting the angle of the first reflecting mirror 81 while monitoring the position of the beam on the image plane. When adjusting the angle, an arm (not shown) is pressed against the first reflecting mirror 81 to move the first reflecting mirror 81. After the angle adjustment is complete, the first reflecting mirror 81 is fixed to the support member Fs by irradiating the photocurable resin P with light.

[0065] As shown in FIG. 2, the scanning optical device 1 further includes a first laser holder H11, a second laser holder H12, a first lens holder H21, and a second lens holder H22.

[0066] The first laser holder H11 is a member that is L-shaped in cross section and holds the first semiconductor laser 10Y, the second semiconductor laser 10M, and the first coupling lens 20Y. The first coupling lens 20Y is fixed to the first laser holder H11 by a photocurable resin. The first coupling lens 20Y can be attached to the first laser holder H11 from the other side in the first direction. The first laser holder H11 is fixed to the frame F. Note that the second laser holder H12 is configured similarly to the first laser holder H11 except for the object that it holds, and therefore a description thereof will be omitted.

[0067] The first lens holder H21 is a member that holds the second coupling lens 20M in a position aligned with the first coupling lens 20Y in the first direction. The first lens holder H21 has a cylindrical portion into which the second coupling lens 20M is fitted. The first lens holder H21 is fixed to the first laser holder H11 by a photocurable resin. The first lens holder H21 is attachable to the first laser holder H11 from the other side in the first direction. The second lens holder H22 is configured similarly to the first lens holder H21 except that the object that it holds and the fixed destination are changed to the second laser holder H12, and therefore a description thereof will be omitted.

[0068] When attaching the coupling lens 20 to the frame, first, the laser holders H11 and H12 are fixed to the frame F. After that, photocurable resin is applied to the first coupling lens 20Y or the first laser holder H11, and the position of the first coupling lens 20Y is adjusted relative to the first semiconductor laser 10Y. After adjusting the position, the first coupling lens 20Y is fixed to the first laser holder H11 by irradiating the photocurable resin with light. The fourth coupling lens 20K is also fixed to the second laser holder H12 using the same method as the first coupling lens 20Y.

[0069] After that, photocurable resin is applied to the first lens holder H21 or the first laser holder H11 holding the second coupling lens 20M, and the position of the second coupling lens 20M is adjusted relative to the second semiconductor laser 10M. After adjusting the position, the first lens holder H21 is fixed to the first laser holder H11 by shining light onto the photocurable resin. The third coupling lens 20C is also fixed to the second laser holder H12 via the second lens holder H22 using the same method as the second coupling lens 20M.

[0070] 9, the scanning optical device 1 further includes a cover C. The cover C has a first cover C1 and a second cover C2.

[0071] The first cover C1 is a cover that covers the deflector 50 and the first base wall Fb1 from one side in the first direction. More specifically, the first cover C1 covers the first recess CP1.

[0072] The second cover C2 is a cover that covers the coupling lens 20 and the second base wall Fb2 from the other side in the first direction. More specifically, the second cover C2 covers the second recess CP2.

[0073] The scanning optical device 1 further includes a first screw N1, a second screw N2, and two third screws N3. The first screw N1 and the second screws N2 are screws for fixing the first cover C1 to the frame F. Each of the third screws N3 is a screw for fixing the second cover C2 to the frame F.

[0074] 10, the frame F has a first boss F51 to which a first screw N1 is fastened and a second boss F52 to which a second screw N2 is fastened. The first boss F51, the rotation axis X1 of the polygon mirror 51, and the second boss F52 are aligned in the third direction. Specifically, the first boss F51 and the second boss F52 are located on a straight line LN that extends in the third direction and passes through the rotation axis X1. The rotation axis X1 is located between the first boss F51 and the second boss F52 in the third direction. Furthermore, the first boss F51 is located between the optical paths of two beams, for example, beams BY and BK, that are spaced apart in the second direction.

[0075] 11, when the first cover C1 is attached to the frame F, the rotation axis X1 is located between the first screw N1 and the second screw N2 in the third direction. The first screw N1 and the second screw N2 are located on the aforementioned straight line LN. Furthermore, the first screw N1 is located between the optical paths of the two beams BY and BK that are spaced apart in the second direction.

[0076] As shown in FIG. 12, the first cover C1 has two second ribs R21 and R22. Each of the second ribs R21 and R22 overlaps with the second wall F2 when viewed in the direction of propagation of the beam incident on the first scanning lens 60YM (see FIG. 13), specifically, when viewed from the second direction. Each of the second ribs R21 and R22 extends in the third direction. The distance between each of the second ribs R21 and R22 and the second wall F2 in the second direction is smaller than the thickness of the second wall F2. The two second ribs R21 and R22 sandwich the second wall F2 in the second direction. The second rib R21, which is farther from the polygon mirror 51, protrudes closer to the first base wall Fb1 than the second rib R22, which is closer. Two second ribs R21 and R22 are also similarly provided on the second wall F2 on the other side of the polygon mirror 51 in the second direction.

[0077] As shown in Fig. 13, the scanning optical device 1 further includes a seal member SL located between the first scanning lens 60YM and the second rib R21 of the first cover C1. The seal member SL is made of an elastic material such as sponge. The seal member SL, together with the first scanning lens 60YM, closes the second opening F21 (see Fig. 3) in the second wall F2. A similar seal member SL is also provided for the first scanning lens 60CK located on the other side of the polygon mirror 51 in the second direction.

[0078] As shown in Fig. 14, the second cover C2 has a first rib R1 and two third ribs R3. The first rib R1 extends in the second direction. The two third ribs R3 are arranged at a distance from each other in the second direction at the center of the first rib R1 in the second direction. Each third rib R3 protrudes further toward the second base wall Fb2 than the first rib R1 (see Fig. 15).

[0079] 15, the first rib R1 overlaps with the first wall F1 when viewed in the traveling direction of the beam incident on the condenser lens 40, more specifically, when viewed from the third direction. The distance in the third direction between the first rib R1 and the first wall F1 is equal to or less than the thickness of the first wall F1.

[0080] 4, the third rib R3 overlaps with the first wall F1 when viewed from the third direction. The distance in the third direction between the third rib R3 and the first wall F1 is smaller than the thickness of the first wall F1. The third rib R3 sandwiches the condenser lens 40 between itself and the frame F.

[0081] Next, the operation of adjusting the positions and orientations of the members of the scanning optical device 1 will be described. 1 and 2, when adjusting the position of the coupling lens 20, a jig for holding the coupling lens 20 or the lens holders H21, H22 is inserted into the second recess CP2 from the other side in the first direction. Therefore, the position adjustment device is disposed on the other side in the first direction of the frame F.

[0082] Furthermore, when performing an inspection to detect the beam incident on the polygon mirror 51, the inspection device is placed into the first recess CP1 from one side in the first direction. Therefore, the inspection device is placed on one side of the frame F in the first direction.

[0083] When adjusting the angle of the reflecting mirror 81, a jig holding the reflecting mirror 81 is brought into contact with the reflecting mirror 81 from the other side in the first direction. Therefore, an angle adjustment device is disposed on the other side of the frame F in the first direction. At that time, the beam is detected by an inspection device disposed on one side of the second scanning lens 70 in the first direction. It is possible to dispose the beam detection device on one side of the frame F in the first direction, and dispose the device for adjusting the position of the coupling lens 20 and the device for adjusting the angle of the reflecting mirror 81 on the other side of the frame F in the first direction. Since the detection device and the adjustment device can be disposed on opposite sides of the frame F, structural constraints on the manufacturing equipment can be alleviated. Furthermore, this makes it possible to continuously adjust the position of the coupling lens 20 and the angle of the reflecting mirror 81 while the frame F is fixed to the manufacturing equipment.

[0084] As described above, the following effects can be obtained in this embodiment. Since a device for adjusting the position of the coupling lens 20 can be placed on the other side of the frame F in the first direction, and a device for detecting light incident on the polygon mirror 51 can be placed on one side of the frame F in the first direction, constraints on the structure of the equipment can be alleviated.

[0085] By arranging the deflector 50 and a part of the scanning optical system Lo on the same side of the first base wall Fb1, the mounting directions of the deflector 50 and a part of the scanning optical system Lo are the same, so that the scanning optical system Lo can be positioned with high precision.

[0086] Since the beam from the scanning optical system Lo is configured to be emitted to one side in the first direction, the beam emitted from the scanning optical system Lo can be measured from the opposite side to the device for adjusting the position of the coupling lens 20.

[0087] Since the reflecting mirror 81 is exposed on the other side in the first direction relative to the first base wall Fb1, the coupling lens 20 and the reflecting mirror 81 that require adjustment can be adjusted from the same side.

[0088] Since the first cover C1 is provided to cover the deflector 50 and the first base wall Fb1 from one side in the first direction, the first cover C1 can prevent dust from adhering to the deflector 50.

[0089] Since the second cover C2 is provided to cover the coupling lens 20 and the second base wall Fb2 from the other side in the first direction, the adhesion of dust to the coupling lens 20 can be prevented by the second cover C2.

[0090] Since the rotation axis X1 of the polygon mirror 51 is located between the first screw N1 and the second screw N2 in the main scanning direction, the sealing performance of the portion of the frame F where the deflector 50 is arranged can be improved.

[0091] Since the first openings F11, F12 through which the beam traveling from the coupling lens 20 to the polygon mirror 51 passes are blocked by the condenser lens 40, dust near the coupling lens 20 can be prevented from moving toward the polygon mirror 51 and adhering to the polygon mirror 51.

[0092] Since the second cover C2 has the first rib R1 that overlaps with the first wall F1 when viewed from the third direction, it is possible to improve the sealing performance between the first wall F1 and the second cover C2.

[0093] Since the condenser lens 40 is sandwiched between the first wall F1 and the diaphragm plate 30, the condenser lens 40 can be brought into close contact with the first wall F1, thereby improving the airtightness.

[0094] The second openings F21, F22 through which the beam reflected by the polygon mirror 51 passes are blocked by the first scanning lenses 60YM, 60CK, so that dust near the scanning optical system Lo can be prevented from moving toward the polygon mirror 51 and adhering to the polygon mirror 51.

[0095] Since the seal member SL is provided between the first scanning lenses 60YM, 60CK and the first cover C1, it is possible to improve the sealing performance between the first scanning lenses 60YM, 60CK and the first cover C1.

[0096] Since the first cover C1 has the second ribs R21, R22 that overlap with the second wall F2 when viewed from the second direction, it is possible to improve the sealing performance between the first cover C1 and the second wall F2.

[0097] The cover may also cover the deflector and at least a part of the scanning optical system.

[0098] Since the first cover C1 covers the deflector 50 and part of the scanning optical system Lo, the deflector 50 and part of the scanning optical system Lo can be sealed together by the first cover C1.

[0099] The present invention is not limited to the above-described embodiment, but can be used in various forms as exemplified below.

[0100] In the above embodiment, a part of the scanning optical system Lo is attached to one side of the first base wall Fb1 in the first direction, but the present invention is not limited to this. For example, the entire scanning optical system may be attached to one side of the first base wall in the first direction.

[0101] In the above embodiment, the first side wall F41, the second side wall F42, the third side wall F43 and the fourth side wall F44 are provided on the frame F, but the present invention is not limited to this, and at least one of the four side walls may be provided on the cover.

[0102] The cover only needs to cover at least the portion of the frame where the deflector is disposed. For example, a cover that covers the deflector and a cover that covers part of the scanning optical system may be separate. Alternatively, the cover may cover the entire scanning optical system. For example, if the entire scanning optical system is housed in the first recess, the cover may cover the entire scanning optical system.

[0103] The number of first ribs and second ribs is not limited to that in the above embodiment and may be any number. Also, two first ribs may be provided and the first wall may be sandwiched between the two first ribs.

[0104] In the above embodiment, the support member Fs having the seating surface FsZ is configured as a member different from the frame F. However, the seating surface FsZ may be provided integrally with the frame F.

[0105] The semiconductor laser 10 may be configured to have a plurality of light-emitting points, so that a plurality of light beams from the semiconductor laser 10 are converted into a plurality of beams by one coupling lens 20, and the plurality of beams are imaged on the surface of the photosensitive drum 200 by corresponding scanning optical systems Lo. In this configuration, the beams BY, BM, BC, and BK in the above embodiment each include a plurality of beams.

[0106] In the above embodiment, a scanning optical device applied to a color image forming apparatus has been exemplified, but the scanning optical device may also be applied to a monochrome image forming apparatus that scans with only one beam.

[0107] The elements described in the above-described embodiment and modified examples may be implemented in any combination. [Explanation of symbols]

[0108] 1. Scanning optical device 10 Semiconductor laser 20 Coupling Lens 50 Deflector 51 Polygon Mirror F Frame Fb1 1st base wall Fb2 2nd base wall Lo scanning optics X1 rotation axis

Claims

1. a semiconductor laser that emits light; a coupling lens that converts light from the semiconductor laser into a beam; a deflector having a polygon mirror that deflects the beam from the coupling lens; a scanning optical system that forms an image of the beam deflected by the deflector on an image plane; a frame to which the deflector is fixed, The frame is a first base wall that intersects with a first direction along a rotation axis of the polygon mirror and to which the deflector is attached; a second base wall that intersects with the first direction and is positioned at a position shifted to one side in the first direction relative to the first base wall, the deflector is located on one side of the first base wall in the first direction, the coupling lens is located on the other side in the first direction with respect to the second base wall, the scanning optical system includes a reflecting mirror that reflects the beam toward an image plane located on one side of the scanning optical system in the first direction, a surface of the reflecting mirror on the other side in the first direction exposed on the other side in the first direction with respect to the first base wall;

2. The frame is 2. The scanning optical device according to claim 1, further comprising a first wall positioned between the deflector and the coupling lens, connecting the first base wall and the second base wall, and having an opening through which the beam from the coupling lens passes.

3. The frame is 3. The scanning optical device according to claim 2, further comprising an aperture stop located on the other side of the second base wall in the first direction and through which the beam from the coupling lens passes.

4. 4. The scanning optical device according to claim 1, wherein at least a part of the scanning optical system is attached to one side of the first base wall in the first direction.

5. 5. The scanning optical device according to claim 1, further comprising a first cover that covers the deflector and the first base wall from one side in the first direction.

6. 6. The scanning optical device according to claim 5, further comprising a second cover that covers the coupling lens and the second base wall from the other side in the first direction.

7. the scanning optical system is disposed on one side of the polygon mirror in a second direction perpendicular to the first direction, and a beam deflected in a main scanning direction perpendicular to the first direction and the second direction is incident on the scanning optical system; the scanning optical device further includes a first screw and a second screw that fix the first cover to the frame; 7. The scanning optical device according to claim 5, wherein the rotation axis is located between the first screw and the second screw in the main scanning direction.

8. a plurality of the semiconductor lasers and the coupling lenses; two beams among the plurality of beams emitted from the coupling lenses are spaced apart in the second direction; 8. The scanning optical device according to claim 7, wherein the first screw is located between the optical paths of the two beams.

9. a semiconductor laser that emits light; a coupling lens that converts light from the semiconductor laser into a beam; a deflector having a polygon mirror that deflects the beam from the coupling lens; a scanning optical system that forms an image of the beam deflected by the deflector on an image plane; a frame to which the deflector is fixed, The frame is a first base wall that intersects with a first direction along a rotation axis of the polygon mirror and to which the deflector is attached; a second base wall that intersects with the first direction and is positioned at a position shifted to one side in the first direction relative to the first base wall, the deflector is located on one side of the first base wall in the first direction, the coupling lens is located on the other side in the first direction with respect to the second base wall, a first cover that covers the deflector and the first base wall from one side in the first direction; the scanning optical system is disposed on one side of the polygon mirror in a second direction perpendicular to the first direction, and a beam deflected in a main scanning direction perpendicular to the first direction and the second direction is incident on the scanning optical system; a first screw and a second screw for fixing the first cover to the frame; 2. A scanning optical device according to claim 1, wherein the rotation axis is located between the first screw and the second screw in the main scanning direction.

Images