Scanning optical device and method for manufacturing the same

Abstract

To enable a plurality of coupling lenses to be attached from the same direction, thereby suppressing the complexity of manufacturing processes from increasing.SOLUTION: A scanning optical device comprises: a first coupling lens 20Y and a second coupling lens 20M for converting light from semiconductor lasers 10Y, 10M into a beam; a polygon mirror for deflecting a beam from the coupling lens 20; a first holding member (first laser holder H11) having a seat surface Hf where the first coupling lens 20Y is secured by a photocurable resin P; and a second holding member (first lens holder H21) for holding the second coupling lens 20M. The second semiconductor laser 10M is aligned to the first semiconductor laser 10Y in the direction of rotation axis of the polygon mirror. The second holding member holds the second coupling lens 20M at a position aligned to the first coupling lens 20Y in the direction of the rotation axis, and is secured to the first holding member with a photocurable resin P.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to a scanning optical device including a plurality of semiconductor lasers and coupling lenses, and a method for manufacturing the scanning optical device. [Background technology]

[0002] Conventionally, a known scanning optical device includes a holder into which two semiconductor lasers are press-fitted and which has two seating surfaces for mounting two coupling lenses (see Patent Document 1). Specifically, in this technology, the holder has a wall located between the two coupling lenses, and one surface and the other surface of the wall serve as seating surfaces for mounting each coupling lens. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-144952 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional technology, it is necessary to attach one coupling lens from one side to a seating surface located on one side of the wall, and then attach the other coupling lens to the seating surface on the other side from the opposite direction to the attachment direction of the one coupling lens, which creates a problem of complicating the manufacturing process.

[0005] Therefore, an object of the present invention is to prevent the manufacturing process from becoming complicated by making it possible to attach a plurality of coupling lenses from the same direction. [Means for solving the problem]

[0006] In order to solve the above problem, the scanning optical device of the present invention includes a first semiconductor laser that emits light, a second semiconductor laser that emits light, a first coupling lens that converts the light from the first semiconductor laser into a beam, a second coupling lens that converts the light from the second semiconductor laser into a beam, a polygon mirror that deflects the beam from the first coupling lens and the beam from the second coupling lens, a first holding member that holds the first coupling lens and has a seating surface to which the first coupling lens is fixed by a photocurable resin, and a second holding member that holds the second coupling lens. The second semiconductor laser is aligned with the first semiconductor laser in the direction of the rotation axis of the polygon mirror. The second holding member holds the second coupling lens at a position aligned with the first coupling lens in the direction of the rotation axis, and is fixed to the first holding member by a photocurable resin.

[0007] According to this configuration, after the first coupling lens is attached to the seat surface of the first holding member from a predetermined direction, the second holding member that holds the second coupling lens can be attached to the first holding member from the predetermined direction. Therefore, multiple coupling lenses can be attached from the same direction, and the manufacturing process can be prevented from becoming complicated.

[0008] The seating surface may be a plane perpendicular to the direction of the rotation axis.

[0009] The second holding member may have a lens mounting portion to which the second coupling lens is attached and legs extending from the lens mounting portion toward the seating surface, and the legs may be fixed to the seating surface by a photocurable resin.

[0010] According to this configuration, since the second holding member has the leg portion extending from the lens mounting portion, it is possible to prevent the lens mounting portion from interfering with the first coupling lens.

[0011] The leg may have a first leg and a second leg spaced apart from the first leg in a direction perpendicular to the rotation axis direction and the optical axis direction of the first semiconductor laser, and light traveling from the first semiconductor laser to the first coupling lens may pass between the first leg and the second leg.

[0012] According to this configuration, the two legs of the second holding member are fixed to the seating surface, so that the second coupling lens can be stably held by the second holding member.

[0013] The second holding member may be made of a material that is transmissive to light for curing the photocurable resin.

[0014] According to this configuration, when fixing the second holding member to the first holding member, light can be passed through the second holding member to harden the photocurable resin, making it easy to fix the second holding member to the first holding member.

[0015] The first holding member may also have a first portion having the seating surface and a second portion extending from the first portion in the direction of the rotation axis, the second portion holding the first semiconductor laser and the second semiconductor laser.

[0016] According to this configuration, the portion that holds the first semiconductor laser and the seating surface that fixes the first coupling lens are integrated, so that the positional accuracy of the first coupling lens relative to the first semiconductor laser can be improved.

[0017] The first holding member and the second holding member may be made of resin.

[0018] According to this configuration, the linear expansion coefficients of the first holding member and the second holding member can be made the same, so that it is possible to prevent the positions of the first coupling lens and the second coupling lens from shifting when each holding member linearly expands.

[0019] Furthermore, the present invention provides a method for manufacturing a scanning optical device comprising: a first semiconductor laser that emits light; a second semiconductor laser that emits light; a first coupling lens that converts light from the first semiconductor laser into a beam; a second coupling lens that converts light from the second semiconductor laser into a beam; a polygon mirror that deflects the beam from the first coupling lens and the beam from the second coupling lens; a first holding member that has a seat to which the first coupling lens is fixed and that holds the first coupling lens; and a second holding member that holds the second coupling lens, wherein the second semiconductor laser is aligned with the first semiconductor laser in the direction of the rotation axis of the polygon mirror, and the second holding member holds the second coupling lens in a position aligned with the first coupling lens in the direction of the rotation axis. The method for manufacturing a scanning optical device includes a first bonding step of adjusting the position of the first coupling lens relative to the first semiconductor laser and adhesively fixing the first coupling lens to the seating surface of the first holding member, and a second bonding step of adjusting the position of the second coupling lens relative to the second semiconductor laser and adhesively fixing the second holding member to which the second coupling lens is attached to the first holding member.

[0020] According to this manufacturing method, after the first coupling lens is attached to the seat surface of the first holding member from a predetermined direction, the second holding member that holds the second coupling lens can be attached to the first holding member from the predetermined direction. Therefore, multiple coupling lenses can be attached from the same direction, and the manufacturing process can be prevented from becoming complicated.

[0021] Furthermore, in the first bonding step, a photocurable resin may be placed between the first coupling lens and the seating surface, and after adjusting the position of the first coupling lens, the first coupling lens may be bonded and fixed to the seating surface by irradiating light onto the photocurable resin; and in the second bonding step, a photocurable resin may be placed between the second holding member and the first holding member, and after adjusting the position of the second coupling lens, the second holding member may be bonded and fixed to the first holding member by irradiating light onto the photocurable resin.

[0022] Furthermore, the position of the first coupling lens may be adjusted using a jig that clamps the first coupling lens in a direction perpendicular to the optical axis direction of the first semiconductor laser and the rotation axis direction.

[0023] Furthermore, the second holding member may be sandwiched between the jigs in the orthogonal direction to adjust the position of the second coupling lens. [Effects of the Invention]

[0024] According to the present invention, since a plurality of coupling lenses can be attached from the same direction, it is possible to prevent the manufacturing process from becoming complicated. [Brief explanation of the drawings]

[0025] [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. 1A is an oblique view showing the first laser holder, FIG. 1B is a rear view of the first laser holder seen from the other side in the third direction, and FIG. 1C is a side view of the first laser holder with a portion thereof broken away. [Figure 7] FIG. 2 is an exploded perspective view showing the relationship between a frame and a laser holder. [Figure 8] 10A is a view of the frame as seen from the other side in the third direction, and FIG. 10B is a cross-sectional view showing a hole that forms an aperture stop. [Figure 9] FIG. 2(a) is a perspective view showing a first lens holder, and FIG. 2(b) is a diagram showing the relationship between the light from a first semiconductor laser and the first lens holder. [Figure 10] 10(a) to 10(d) are diagrams showing a method for attaching a coupling lens to a frame. [Figure 11] FIG. 10 is a perspective view showing the relationship between the insert and the frame. [Figure 12] FIG. 4 is a cross-sectional view showing the state in which the frame has been injection molded using a mold. DETAILED DESCRIPTION OF THE INVENTION

[0026] 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 the "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 the "second direction." A direction perpendicular to the first direction and the second direction is referred to as the "third direction." The third direction corresponds to the optical axis direction of the first semiconductor laser 10Y (described later) and the main scanning direction in the scanning optical system Lo. The first direction corresponds to the sub-scanning direction. The second direction corresponds to the orthogonal direction perpendicular to the rotation axis direction and the optical axis direction. Arrows indicating each direction in the drawings indicate "one side" in each direction.

[0027] 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).

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] The coupling lens 20 is a lens that converts light from the semiconductor laser 10 into a beam. The coupling lenses 20Y, 20M, 20C, and 20K corresponding to each color are arranged in positions facing the corresponding semiconductor lasers 10Y, 10M, 10C, and 10K. The coupling lens 20 has axially symmetric optical surfaces on both the entrance and exit surfaces, and is a resin lens with refractive power and diffractive power.

[0033] 1, the diaphragm plate 30 is a portion having an aperture stop 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. The diaphragm plate 30 has a plurality of aperture stops 31Y, 31M, 31C, and 31K in number corresponding to the plurality of semiconductor lasers 10Y, 10M, 10C, and 10K.

[0034] 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. In other words, the condenser lens 40 is disposed between the aperture diaphragm 31 and the polygon mirror 51.

[0035] 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.

[0036] 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.

[0037] 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.

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

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] The frame F is made of resin and is integrally formed by molding. The frame F has a first recess CP1 shown in FIG. 3 and a second recess CP2 shown in FIG. 1. 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.

[0049] As shown in FIG. 1, 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.

[0050] 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.

[0051] The second base wall Fb2 is positioned at a position offset to one side in the first direction with respect to the first base wall Fb1. As shown in FIG. 5, the deflector 50 and the aforementioned part of the scanning optical system Lo are directly or indirectly attached to the first base wall Fb1 from one side in the first direction. Therefore, the deflector 50 and part of the scanning optical system Lo are positioned on one side in the first direction with respect 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 positioned on the other side in the first direction with respect to the second base wall Fb2. Also, as shown in FIG. 1, the condenser lens 40 and the reflecting mirror 81 are positioned on the other side in the first direction with respect to the second base wall Fb2.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 2, the scanning optical device 1 further includes a first laser holder H11 and a second laser holder H12 as an example of a first holding member, and a first lens holder H21 and a second lens holder H22 as an example of a second holding member. The first laser holder H11, the second laser holder H12, the first lens holder H21, and the second lens holder H22 are made of resin. The first lens holder H21 and the second lens holder H22 are made of a material that is transmissive to light for curing the photocurable resin.

[0059] The first laser holder H11 is a member having an L-shape in cross section that 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. The structure of the first laser holder H11 will be described in detail later. 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 will not be described again.

[0060] 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 is fixed to the first laser holder H11 by a photocurable resin. The first lens holder H21 can be attached to the first laser holder H11 from the other side in the first direction. The structure of the first lens holder H21 will be described in detail later. Note that the second lens holder H22 is configured in the same way as 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.

[0061] As shown in FIG. 6(a), the first laser holder H11 has a first portion 111, a second portion 112, two third portions 113, a first holder positioning portion 114, and a second holder positioning portion 115.

[0062] The first portion 111 is a plate-shaped portion whose thickness direction is along the first direction, and whose dimension in the third direction is greater than its dimension in the second direction. The first portion 111 has a seating surface Hf. The seating surface Hf has a first seating surface Hf1 and a second seating surface Hf2. The first seating surface Hf1 and the second seating surface Hf2 are flat surfaces perpendicular to the first direction. The first seating surface Hf1 and the second seating surface Hf2 face the other side in the first direction. As shown in FIG. 6(c), the first portion 111 is disposed with a gap between it and the frame F in the first direction.

[0063] The first seating surface Hf1 is a seating surface to which the first coupling lens 20Y is fixed by a photocurable resin. The first seating surface Hf1 is located at one end of the first portion 111 in the third direction.

[0064] The second seating surfaces Hf2 are seating surfaces to which the first lens holder H21 is fixed by photocurable resin. One second seating surface Hf2 is provided at each end of the first portion 111 in the second direction. The second seating surfaces Hf2 are located on the other side in the first direction than the first seating surfaces Hf1.

[0065] As shown in FIG. 6(a), the second portion 112 extends from the other end of the first portion 111 in the third direction toward the other side in the first direction. The second portion 112 has a first holding portion 112A that holds the first semiconductor laser 10Y and a second holding portion 112B that holds the second semiconductor laser 10M. The first holding portion 112A and the second holding portion 112B each have a hole that penetrates in the third direction and a pair of semi-cylindrical ribs that extend from the periphery of the hole toward the other side in the third direction. The semiconductor laser 10 is held by being press-fitted between the pair of ribs.

[0066] The third portions 113 extend from the first portion 111 toward one side in the first direction. One third portion 113 is provided at each end of the first portion 111 in the second direction. The third portions 113 are formed over a predetermined range from the end of the first portion 111 on the other side in the third direction. The first portion 111 protrudes further toward one side in the third direction than the third portion 113.

[0067] As shown in FIGS. 6(b) and 6(c), the first holder positioning portion 114 is a portion for positioning the first laser holder H11 relative to the frame F. The first holder positioning portion 114 extends from the first portion 111 toward one side in the first direction. The first holder positioning portion 114 is located between and connected to the two third portions 113. The first holder positioning portion 114 has a surface 114A for positioning the first laser holder H11 in the third direction and a hole 114B for positioning the first holder positioning portion 114 in the first and second directions.

[0068] As shown in Fig. 6(c), the frame F has a boss F51 as an example of a first contact portion. The boss F51 has a cylindrical shape that is convex toward the other side in the third direction. The boss F51 has a contact surface F511 that contacts the surface 114A of the first holder positioning portion 114 in the third direction, and a protrusion F512 that fits into the hole 114B. The protrusion F512 protrudes from the center of the contact surface F511.

[0069] A hole F513 (see FIG. 7) into which a screw N is inserted is formed in the center of the tip surface of the protrusion F512. The first holder positioning portion 114 is fixed to the frame F in the third direction by the screw N. More specifically, the first holder positioning portion 114 is sandwiched between the head of the screw N and the contact surface F511 of the boss F51.

[0070] As shown in FIG. 6(b), the second holder positioning portion 115 is a portion that restricts the rotation of the first laser holder H11 around the boss F51. The second holder positioning portion 115 extends from the end of the second portion 112 on the other side in the first direction to the other side in the third direction, and then extends again to the other side in the first direction. The second holder positioning portion 115 has a groove 115A that restricts the rotation of the first laser holder H11. The groove 115A penetrates in the third direction and opens to the other side in the first direction.

[0071] The frame F has a contact rib F52 as an example of a second contact portion. The contact rib F52 has a shape that is convex toward one side in the first direction and convex toward the other side in the third direction (see FIG. 7). When the first laser holder H11 is attached to the frame F, the contact rib F52 is received in the groove 115A of the second holder positioning portion 115. The contact rib F52 contacts the groove 115A in the second direction. A gap is formed between the second holder positioning portion 115 and the frame F in the first direction to allow thermal expansion to escape.

[0072] First holder positioning portion 114, first holding portion 112A, second holding portion 112B, and second holder positioning portion 115 are arranged in this order from one side in the first direction. First holding portion 112A and second holding portion 112B are located between first holder positioning portion 114 and second holder positioning portion 115 in the first direction. Furthermore, the above-mentioned first portion 111 is located between first holding portion 112A and first holder positioning portion 114 in the first direction.

[0073] Therefore, when the semiconductor lasers 10Y and 10M are attached to the first laser holder H11, the first holder positioning portion 114, the first semiconductor laser 10Y, the second semiconductor laser 10M, and the second holder positioning portion 115 are arranged in this order in the arrangement direction of the semiconductor lasers 10Y and 10M. Furthermore, when the semiconductor lasers 10Y and 10M are attached to the first laser holder H11, each semiconductor laser 10Y and 10M is positioned between the first holder positioning portion 114 and the second holder positioning portion 115 in the arrangement direction. Furthermore, when the semiconductor lasers 10Y and 10M are attached to the first laser holder H11, the first semiconductor laser 10Y is positioned between the second semiconductor laser 10M and the first holder positioning portion 114 in the arrangement direction. Furthermore, in a state in which the semiconductor lasers 10Y and 10M are attached to the first laser holder H11, the first portion 111 is located between the first semiconductor laser 10Y and the first holder positioning portion 114 in the arrangement direction.

[0074] As shown in Figure 7, the frame F has two positioning portions F50, each having the aforementioned boss F51 and contact rib F52. The positioning portion F50 on one side in the second direction positions the first laser holder H11, and the positioning portion F50 on the other side in the second direction positions the second laser holder H12. Each boss F51 protrudes from the second base wall Fb2 of the frame F toward the other side in the third direction. The bosses F51 are arranged at intervals in the second direction.

[0075] The second side wall F42 is located on the opposite side of the bosses F51 from the deflector 50 (see FIG. 1). The second side wall F42 has openings F421 that expose the aperture stops 31Y, 31M, 31C, and 31K and the bosses F51 to the outside.

[0076] The opening F421 penetrates in the third direction and opens to one side in the first direction. Contact ribs F52 are formed on the edge of the opening F421 on the other side in the first direction. Each contact rib F52 protrudes from the edge of the opening F421 to one side in the first direction.

[0077] 8(a), when no other components are attached to the frame F, the aperture stops 31Y, 31M, 31C, and 31K and the positioning portion F50 are visible from the third direction. The aperture stops 31Y and 31M and the positioning portion F50 on one side in the second direction are aligned on a straight line along the first direction when viewed from the third direction. The aperture stops 31C and 31K and the positioning portion F50 on the other side in the second direction are aligned on a straight line along the first direction when viewed from the third direction.

[0078] The aperture stops 31Y and 31M are located in the first direction between the boss F51 and the contact rib F52 on one side in the second direction, and the aperture stops 31C and 31K are located in the first direction between the boss F51 and the contact rib F52 on the other side in the second direction.

[0079] 8(b), the aperture diaphragm 31 is formed by a hole 32 whose opening is closer to the condenser lens 40 than the opening farther from the condenser lens 40. The aperture diaphragm 31 is the opening of the hole 32 that is closer to the condenser lens 40.

[0080] 9(a), the first lens holder H21 has a lens mounting portion 211 and leg portions 212. The lens mounting portion 211 is a portion where the second coupling lens 20M is mounted. The lens mounting portion 211 is cylindrical, and the second coupling lens 20M is mounted by fitting to one end portion of the lens mounting portion 211 on one side in the third direction. The lens mounting portion 211 protrudes from the leg portions 212 on one side in the third direction.

[0081] The leg portion 212 has a first leg portion 212A and a second leg portion 212B. The first leg portion 212A and the second leg portion 212B extend from the lens mounting portion 211 to one side in the first direction. As a result, as shown in FIG. 9(b), when the first lens holder H21 is attached to the first laser holder H11, the leg portion 212 extends from the lens mounting portion 211 toward the second seating surface Hf2. The first leg portion 212A and the second leg portion 212B are spaced apart in the second direction. The first leg portion 212A and the second leg portion 212B are each fixed to the second seating surface Hf2 by photocurable resin.

[0082] The first leg 212A and the second leg 212B of the first lens holder H21 are arranged to straddle the optical path of the light from the first semiconductor laser 10Y, so that the light traveling from the first semiconductor laser 10Y to the first coupling lens 20Y passes between the first leg 212A and the second leg 212B.

[0083] Next, we will explain a method for manufacturing the scanning optical device 1. First, we will explain a method for attaching the coupling lens 20 to the frame F, and finally we will explain a method for molding the frame F.

[0084] As shown in Fig. 7, when attaching the coupling lens 20 to the frame F, first, the laser holders H11 and H12 holding the semiconductor laser 10 are attached to the frame F with screws N. After that, the first bonding step shown in Fig. 10(a) and (b) is performed, and then the second bonding step shown in Fig. 10(c) and (d) is performed.

[0085] 10(a), in the first bonding step, first, the first coupling lens 20Y is gripped using a jig J that clamps the first coupling lens 20Y from the second direction. Next, uncured photocurable resin P is placed between the first coupling lens 20Y and the first seating surface Hf1 of the first laser holder H11. Note that the figure shows an example in which the photocurable resin P is applied to the first seating surface Hf1 of the first laser holder H11, and then the first coupling lens 20Y is brought closer to the first seating surface Hf1.

[0086] Next, by moving the jig J to one side in the first direction, the first coupling lens 20Y is brought closer to the first seating surface Hf1 from the other side in the first direction, and the photocurable resin P is sandwiched between the first coupling lens 20Y and the first seating surface Hf1. Thereafter, by moving the jig J in the first direction, second direction, and third direction, the position of the first coupling lens 20Y with respect to the first semiconductor laser 10Y is adjusted.

[0087] After adjusting the position, the first coupling lens 20Y is adhesively fixed to the first seating surface Hf1 of the first laser holder H11 by irradiating the photocurable resin P with light, as shown in Fig. 10(b). The fourth coupling lens 20K is also adhesively fixed to the second laser holder H12 using the same method as the first coupling lens 20Y. In this embodiment, the photocurable resin P is an ultraviolet curable resin, and the light used for curing is ultraviolet light.

[0088] 10(c), in the second bonding step, first, the first lens holder H21 holding the second coupling lens 20M is clamped from the second direction by a jig J. Next, uncured photocurable resin P is placed between the first lens holder H21 and the second seating surface Hf2 of the first laser holder H11. Note that the figure shows an example in which the photocurable resin P is applied to the second seating surface Hf2 of the first laser holder H11 and then the first lens holder H21 is brought closer to the second seating surface Hf2.

[0089] Next, by moving the jig J to one side in the first direction, the first lens holder H21 is brought closer to the second seating surface Hf2 from the other side in the first direction, and the photocurable resin P is sandwiched between the first lens holder H21 and the second seating surface Hf2. Thereafter, by moving the jig J in the first direction, second direction, and third direction, the position of the second coupling lens 20M relative to the second semiconductor laser 10M is adjusted.

[0090] After adjusting the position, the first lens holder H21 is adhered and fixed to the second seating surface Hf2 of the first laser holder H11 by irradiating the photocurable resin P with light, as shown in Fig. 10(d). At this time, the light for curing the photocurable resin P can be irradiated onto the photocurable resin P through the transparent first lens holder H21, so the entire photocurable resin P can be reliably cured. The third coupling lens 20C is also fixed to the second laser holder H12 via the second lens holder H22 in the same manner as the second coupling lens 20M.

[0091] As shown in Figure 12, in the method of molding the frame F, an injection molding die M having a first die M1, a second die M2, and a die insert M3 is used to injection mold the frame F, thereby integrally forming each aperture stop 31 and the positioning portion F50 on the frame F. The first die M1 is a die that forms one surface of the frame F in the first direction. The second die M2 is a die that forms the other surface of the frame F in the first direction. At least one of the first die M1 and the second die M2 is movable in the first direction.

[0092] The insert M3 is a mold for forming the positioning portion F50 of the frame F and the aperture stop 31. The insert M3 is movable in the third direction.

[0093] As shown in FIG. 11, the insert M3 integrally has a first printing surface M31 and two second printing surfaces M32 and M33. The first printing surface M31 is a surface for forming four aperture stops 31. The first printing surface M31 has four protrusions M311 for forming the four aperture stops 31, more specifically, four holes 32 (see FIG. 8). The area of ​​the tip of the protrusions M311 when projected in the third direction is smaller than the cross-sectional area of ​​the portion closer to the first printing surface M31. This makes it possible to form a small opening on the side of the hole 32 closer to the condenser lens 40, and also makes it easy to move the insert M3 in the third direction away from the frame F.

[0094] The second printing surface M32 is a surface for forming the two bosses F51. The second printing surface M32 has two recesses M321 for forming the two bosses F51. The second printing surface M33 is a surface for forming the two contact ribs F52 (see FIG. 8). The second printing surface M33 has two recesses M331 for forming the two contact ribs F52.

[0095] The method for forming the frame F includes a first step, a second step, and a third step. As shown in FIG. 12, in the first step, a frame F is formed by injecting resin into a mold M in which a first die M1, a second die M2, and a core M3 are combined.

[0096] In a second step, after the frame F is formed, at least one of the first mold M1 and the second mold M2 is moved in a first direction and separated from the frame F. In a third step, after the frame F is formed, the insert M3 is moved in a third direction and separated from the frame F. By going through the steps described above, it is possible to form each aperture stop 31 and the positioning portion F50 integrally with the frame F.

[0097] As described above, the following effects can be obtained in this embodiment. After the first coupling lens 20Y is attached to the first seating surface Hf1 from the other side in the first direction, the first lens holder H21 that holds the second coupling lens 20M can be attached to the second seating surface Hf2 from the other side in the first direction, so that multiple coupling lenses 20 can be attached from the same direction, and the manufacturing process can be prevented from becoming complicated.

[0098] Since the first lens holder H21 has the leg portion 212 extending from the lens mounting portion 211, it is possible to prevent the lens mounting portion 211 from interfering with the first coupling lens 20Y.

[0099] Since the two legs 212A and 212B of the first lens holder H21 are fixed to the first laser holder H11, the second coupling lens 20M can be stably held by the first lens holder H21.

[0100] When fixing the first lens holder H21 to the first laser holder H11, light can be passed through the transparent first lens holder H21 to harden the photocurable resin P, making it easy to fix the first lens holder H21 to the first laser holder H11.

[0101] Since the second portion 112 that holds the first semiconductor laser 10Y and the seating surface Hf that fixes the first coupling lens 20Y are integrated, the positional accuracy of the first coupling lens 20Y relative to the first semiconductor laser 10Y can be improved.

[0102] Because the first laser holder H11 and the first lens holder H21 are both made of resin, the linear expansion coefficients of the first laser holder H11 and the first lens holder H21 can be made the same, which makes it possible to prevent the first coupling lens 20Y and the second coupling lens 20M from shifting in position when the first laser holder H11 and the first lens holder H21 thermally expand.In addition, by utilizing the linear expansion coefficients of the first laser holder H11 and the first lens holder H21, it is possible to achieve a configuration that compensates for changes in the refractive power and diffractive power of the first coupling lens 20Y and the second coupling lens 20M that occur due to temperature fluctuations.

[0103] Since the holder positioning portions 114, 115 and the semiconductor lasers 10Y, 10M are aligned in the arrangement direction, tolerance management can be facilitated.

[0104] Since the first semiconductor laser 10Y and the second semiconductor laser 10M are arranged in the sub-scanning direction, the first semiconductor laser 10Y and the second semiconductor laser 10M that expose different image surfaces can be attached to one first laser holder H11.

[0105] Since the frame F has the boss F51 that comes into contact with the first holder positioning portion 114 in the third direction, the first laser holder H11 can be positioned relative to the frame F in the third direction.

[0106] Since the frame F has the contact rib F52 that comes into contact with the second holder positioning portion 115 in the second direction, rotation of the first laser holder H11 relative to the frame F can be suppressed.

[0107] Since the first coupling lens 20Y is fixed to the seating surface Hf by the photocurable resin, the first coupling lens 20Y that has been adjusted relative to the first semiconductor laser 10Y can be fixed to the seating surface Hf by irradiating the photocurable resin with light.

[0108] Since the first portion 111 is disposed with a gap between it and the frame F in the first direction, the seating surface Hf is not affected by the tolerance between the frame F and the first laser holder H11.

[0109] Since the first laser holder H11 is made of resin, the degree of freedom in the shape of the first laser holder H11 can be increased, and the range in which the linear expansion coefficient can be set can be widened.

[0110] Since the aperture stop 31 and the positioning portion F50 are formed using the same insert M3, the positioning accuracy of the aperture stop 31 and the positioning portion F50 can be improved.

[0111] The hole 32 forming the aperture stop 31 is formed so that the opening closer to the condenser lens 40 is smaller than the opening farther from the condenser lens 40, so that the size of the aperture stop 31, which is the opening closer to the condenser lens 40, can be set to the standard size.

[0112] By providing the second side wall F42, the rigidity of the frame F can be increased, and by forming the opening F421 in the second side wall F42, the aperture stop 31 and the positioning portion F50 can be formed using the same insert M3.

[0113] The present invention is not limited to the above-described embodiment, but can be used in various forms as exemplified below.

[0114] In the above embodiment, the first holding member is a laser holder, but the present invention is not limited to this, and the first holding member may be, for example, a frame of a scanning optical device. In this case, the semiconductor laser may be held by a laser holder attached to the frame, or may be held by the frame.

[0115] In the above embodiment, the second holding member is fixed to the seating surface of the first holding member with a photocurable resin, but the present invention is not limited to this. For example, the second holding member may be fixed to a portion of the first holding member other than the seating surface with a photocurable resin. Furthermore, the number of legs of the second holding member may be one or three or more.

[0116] In the above embodiment, the coupling lens, etc. is fixed to the seating surface using a photocurable resin, but the present invention is not limited to this. For example, the coupling lens, etc. may be fixed to the seating surface using an adhesive other than a photocurable resin.

[0117] In the above embodiment, the first lens holder and the second lens holder are made of a transparent resin, but the present invention is not limited to this, and a material other than a transparent resin through which light passes for curing the photocurable resin can be used. Also, a structure that allows light to reach between the first lens holder and the second seating surface, and between the second lens holder and the second seating surface, may be provided.

[0118] In the above embodiment, the positioning portion has a convex shape, but the present invention is not limited to this, and the positioning portion may have a concave shape in the optical axis direction.

[0119] In the above embodiment, the first contact portion is a boss and a hole into which the boss fits is formed in the first holder positioning portion, but the present invention is not limited to this, and the first holder positioning portion may be a boss and a hole into which the boss fits may be formed in the first contact portion.

[0120] 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.

[0121] The elements described in the above-described embodiment and modified examples may be implemented in any combination. [Explanation of symbols]

[0122] 1. Scanning optical device 10Y 1st semiconductor laser 10M Second semiconductor laser 20Y 1st coupling lens 20M Second Coupling Lens 51 Polygon Mirror H11 First laser holder H21 1st lens holder Hf seat P Photocuring resin X1 rotation axis

Claims

1. a first semiconductor laser that emits light; a second semiconductor laser that emits light; a first coupling lens that converts light from the first semiconductor laser into a beam; a second coupling lens that converts the light from the second semiconductor laser into a beam; a polygon mirror that deflects the beam from the first coupling lens and the beam from the second coupling lens; a first holding member that has a seat surface to which the first coupling lens is fixed by a photocurable resin and that holds the first coupling lens; a second holding member that holds the second coupling lens, the second holding member being made of a material that is transmissive to light for curing the photocurable resin; the second semiconductor laser is aligned with the first semiconductor laser in the direction of the rotation axis of the polygon mirror, the second holding member holds the second coupling lens at a position aligned with the first coupling lens in the rotation axis direction, and is fixed to the first holding member by a photocurable resin; the bearing surface is a plane perpendicular to the direction of the rotation axis, The second holding member is a lens mounting portion to which the second coupling lens is attached; a leg portion extending from the lens attachment portion toward the seat surface, The legs are fixed to the seat surface by a photocurable resin, The leg portion is A first leg; a second leg portion spaced from the first leg portion in a direction perpendicular to the rotation axis direction and the optical axis direction of the first semiconductor laser, light traveling from the first semiconductor laser to the first coupling lens passes between the first leg and the second leg; The seating surface is a first seating surface to which the first coupling lens is directly fixed by a photocurable resin; a second seating surface provided on one side and the other side of the first seating surface in the perpendicular direction, and to which the first leg portion and the second leg portion of the second holding member are fixed by a photocurable resin.

2. The first seating surface is located on the opposite side of the second coupling lens with respect to the center of the first coupling lens in the direction of the rotation axis, 2. The scanning optical device according to claim 1, wherein the second seating surface is located on an opposite side to the second coupling lens with respect to the center of the first coupling lens in the direction of the rotation axis.

3. The first leg and the second leg are a first portion extending from the lens attachment portion toward the seating surface; 3. The scanning optical device according to claim 1, further comprising: a second portion extending outward in the orthogonal direction from an end of the first portion on the seating surface side.

4. The lens mounting portion is cylindrical, 4. The scanning optical device according to claim 1, wherein the second coupling lens is fitted to the lens mounting portion.

5. A scanning optical device described in any one of claims 1 to 4, characterized in that the lens mounting portion protrudes toward the polygon mirror in the optical axis direction relative to the leg portion.

6. The first holding member is a first portion having the seating surface; 6. The scanning optical device according to claim 1, further comprising: a second portion extending from the first portion in the direction of the rotation axis, the second portion holding the first semiconductor laser and the second semiconductor laser.

7. 7. The scanning optical device according to claim 1, wherein the first holding member and the second holding member are made of resin.

8. a first semiconductor laser that emits light; a second semiconductor laser that emits light; a first coupling lens that converts light from the first semiconductor laser into a beam; a second coupling lens that converts the light from the second semiconductor laser into a beam; a polygon mirror that deflects the beam from the first coupling lens and the beam from the second coupling lens; a first holding member having a seat surface to which the first coupling lens is fixed and holding the first coupling lens; a second holding member that holds the second coupling lens, the second holding member being made of a material that is transmissive to light for curing the photocurable resin; the second semiconductor laser is aligned with the first semiconductor laser in the direction of the rotation axis of the polygon mirror, the second holding member holds the second coupling lens at a position aligned with the first coupling lens in the rotation axis direction, the bearing surface is a plane perpendicular to the direction of the rotation axis, The second holding member is a lens mounting portion to which the second coupling lens is attached; a leg portion extending from the lens attachment portion toward the seat surface, The legs are fixed to the seat surface by a photocurable resin, The leg portion is A first leg; a second leg portion spaced from the first leg portion in a direction perpendicular to the rotation axis direction and the optical axis direction of the first semiconductor laser, light traveling from the first semiconductor laser to the first coupling lens passes between the first leg and the second leg; The seating surface is a first seating surface to which the first coupling lens is directly fixed by a photocurable resin; a second seating surface provided on one side and the other side of the first seating surface in the orthogonal direction, the second seating surface having the first leg portion and the second leg portion of the second holding member fixed thereto by a photocurable resin, a first bonding step of adjusting a position of the first coupling lens with respect to the first semiconductor laser and bonding and fixing the first coupling lens to the first seating surface of the first holding member; a second bonding step of adjusting the position of the second coupling lens with respect to the second semiconductor laser after the first bonding step, and bonding and fixing the second holding member to which the second coupling lens is attached to the second seating surface of the first holding member.

9. In the first bonding step, a photocurable resin is disposed between the first coupling lens and the first seating surface; After adjusting the position of the first coupling lens, the first coupling lens is bonded and fixed to the first seating surface by applying light to a photocurable resin; In the second bonding step, a photocurable resin is disposed between the second holding member and the second seating surface of the first holding member; 9. The method for manufacturing a scanning optical device according to claim 8, wherein after adjusting the position of the second coupling lens, the second holding member is adhesively fixed to the second seating surface of the first holding member by irradiating light onto a photocurable resin.

10. The first seating surface is located on the opposite side of the second coupling lens with respect to the center of the first coupling lens in the direction of the rotation axis, the second seating surface is located on an opposite side to the second coupling lens with respect to the center of the first coupling lens in the direction of the rotation axis, 10. The method for manufacturing a scanning optical device according to claim 8, wherein the position of the first coupling lens is adjusted using a jig that clamps the first coupling lens in a direction perpendicular to the optical axis direction of the first semiconductor laser and the rotation axis direction.

11. The first leg and the second leg are a first portion extending from the lens attachment portion toward the seating surface; a second portion extending outward in the orthogonal direction from an end of the first portion on the seat surface side, 11. The method for manufacturing a scanning optical device according to claim 10, wherein the position of the second coupling lens is adjusted by clamping the second holding member with the jig in the orthogonal direction.

Images