JP7782238B2 - Scanning optical device and method for manufacturing the same - Google Patents

Description

The present invention relates to a scanning optical device equipped with multiple semiconductor lasers and coupling lenses, and a method for manufacturing a scanning optical device.

Conventionally, a known scanning optical device includes a holder into which two semiconductor lasers are press-fitted, the holder having 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, with one side of the wall and the other side serving as seating surfaces for mounting each coupling lens.

Japanese Patent Application Laid-Open No. 2007-144952

However, with conventional technology, it is necessary to attach one coupling lens to a seating surface located on one side of the wall from one side, 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 first coupling lens, which creates a problem of complicated manufacturing processes.

The present invention aims to prevent the manufacturing process from becoming too complicated by making it possible to attach multiple coupling lenses from the same direction.

In order to solve the above problem, the scanning optical device according to 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 deflector having a polygon mirror that deflects the beam from the first coupling lens and the beam from the second coupling lens, a frame to which the deflector is fixed, a first holding member that has a first seating surface to which the first coupling lens is fixed by a photocurable resin and that holds the first coupling lens, and a second holding member that has a second seating surface to which the second coupling lens is fixed by a photocurable resin and 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 frame.

With this configuration, the first coupling lens is attached to the seat of the first holding member from a predetermined direction, the second holding member is then attached to the frame, and the second coupling lens is then attached to the second holding member from a predetermined direction. This allows multiple coupling lenses to be attached from the same direction, preventing the manufacturing process from becoming too complicated.

Furthermore, the first seating surface and the second seating surface may be planes perpendicular to the direction of the rotation axis.

Furthermore, the second holding member may have a base portion having the second seating surface and legs extending from the base portion toward the opposite side of the second seating surface, and the legs may be fixed to the frame.

With this configuration, the second holding member has legs extending from the base portion, which prevents the base portion from interfering with the first coupling lens.

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

With this configuration, the two legs of the second holding member are fixed to the frame, allowing the second coupling lens to be stably held by the second holding member.

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

With this configuration, the portion that holds the first semiconductor laser and the first seating surface that secures the first coupling lens are integrated, thereby improving the positional accuracy of the first coupling lens relative to the first semiconductor laser.

The frame may also have a first positioning surface that positions the first holding member in a first predetermined direction and a second restricting portion that positions the second holding member in the first predetermined direction, and the second restricting portion may intersect with a first plane that includes the first positioning surface.

With this configuration, the second restricting portion is positioned at approximately the same position as the first positioning surface in the first direction, thereby reducing the effects of thermal expansion of each holding member in the first direction.

The frame may also have a first restricting portion that positions the first holding member in a second predetermined direction and a second positioning surface that positions the second holding member in the second predetermined direction, and the first restricting portion may intersect with a second plane that includes the second positioning surface.

With this configuration, the first restricting portion is positioned at approximately the same position as the second positioning surface in the second direction, thereby reducing the effects of thermal expansion of each holding member in the second direction.

Furthermore, the second holding member may be fixed to the frame with screws.

The scanning optical device may further include a third semiconductor laser aligned with the second semiconductor laser in a direction perpendicular to the optical axis direction of the first semiconductor laser and the rotation axis direction, a fourth semiconductor laser aligned with the first semiconductor laser in the orthogonal direction and aligned with the third semiconductor laser in the rotation axis direction, a third coupling lens that converts light from the third semiconductor laser into a beam, and a fourth coupling lens that converts light from the fourth semiconductor laser into a beam, and the third coupling lens may be fixed to the second seating surface with a photocurable resin.

With this configuration, the second coupling lens and third coupling lens are fixed to the second seating surface of the second holding member, which reduces the number of parts compared to, for example, a structure in which the third coupling lens is fixed to a member separate from the second holding member.

Further, 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 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 deflector having a polygon mirror that deflects the beam from the first coupling lens and the beam from the second coupling lens; a frame to which the deflector is fixed; a first holding member that has a first seating surface to which the first coupling lens is fixed and that holds the first coupling lens; and a second holding member that has a second seating surface to which the second coupling lens is fixed and 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 at a position aligned with the first coupling lens in the direction of the rotation axis and is fixed to the frame.
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 first seating surface of the first holding member, an attachment step of attaching the second holding member to the frame, 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 coupling lens to the second seating surface of the second holding member.

This manufacturing method allows the first coupling lens to be attached to the seat of the first holding member from a predetermined direction, the second holding member to be attached to the frame, and then the second coupling lens to be attached to the second holding member from a predetermined direction. This means that multiple coupling lenses can be attached from the same direction, preventing the manufacturing process from becoming too complicated.

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

The position of the first coupling lens may also 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.

Furthermore, the position of the second coupling lens may be adjusted by clamping the second coupling lens with the jig from the perpendicular direction.

According to the present invention, multiple coupling lenses can be attached from the same direction, which helps prevent the manufacturing process from becoming too complicated.

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. FIG. 2 is a perspective view showing the structure around the coupling lens. FIG. 2 is a perspective view of the scanning optical device as seen from one side in a first direction. FIG. 2 is a simplified cross-sectional view taken along line IV-IV in FIG. 1. 2 is a cross-sectional view taken along the line VV in FIG. 1. 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 of the third direction, and FIG. 1C is a side view of the first laser holder with a portion thereof broken away. FIG. 2 is an exploded perspective view showing the relationship between a frame and a laser holder. 10A is a perspective view of the lens holder as seen from one side in the third direction, and FIG. 10B is a perspective view of the lens holder as seen from the other side in the third direction. 10A and 10B are diagrams illustrating the relationship between a second boss and a first positioning surface. 10A and 10B are diagrams illustrating the relationship between a first boss and a second positioning surface. 10A and 10B are diagrams showing a method for attaching the first coupling lens to the frame. 10A to 10C are diagrams showing a method for attaching the second coupling lens to the frame.

As shown in Figures 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, the direction along the rotation axis X1 of the polygon mirror 51 shown in Figure 3 is referred to as the "first direction." Furthermore, the direction perpendicular to the first direction, in which the polygon mirror 51 and the first scanning lens 60 shown in Figure 3 are aligned, is referred to as the "second direction." Furthermore, the direction perpendicular to the first and second directions is referred to as the "third direction." The third direction corresponds to the optical axis direction of the first semiconductor laser 10Y (described below) and the main scanning direction of 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. Furthermore, arrows indicating each direction in the drawings indicate "one side" in each direction.

As shown in Figure 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 Figure 1).

The semiconductor laser 10 is a device that emits light. Four semiconductor lasers 10 are provided, corresponding to the four photosensitive drums 200 (see Figure 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.

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, parts corresponding to the first color may be distinguished by adding "first" to the beginning of their names and adding "Y" to the end of their reference numerals. Similarly, parts corresponding to the second, third, and fourth colors may be distinguished by adding "second," "third," and "fourth" to the beginning of their names and adding "M," "C," and "K" to the end of their reference numerals.

The first semiconductor laser 10Y is arranged with a gap in the first direction relative to the second semiconductor laser 10M. The first semiconductor laser 10Y is located on one side of the second semiconductor laser 10M in the first direction.

The third semiconductor laser 10C is aligned with the second semiconductor laser 10M at a distance in the second direction. The third semiconductor laser 10C is located on the other side of the second semiconductor laser 10M in the second direction. The fourth semiconductor laser 10K is aligned with the third semiconductor laser 10C at a distance in the first direction, and is aligned with the first semiconductor laser 10Y at a distance in the second direction.

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 positioned opposite 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.

As shown in FIG. 1, the aperture plate 30 is a part that has an aperture stop 31 through which the beam from the coupling lens 20 passes, and is formed integrally with the frame F. The aperture plate 30 is located between the coupling lens 20 and the condenser lens 40. The aperture plate 30 has a number of aperture stops 31Y, 31M, 31C, and 31K corresponding to the number of semiconductor lasers 10Y, 10M, 10C, and 10K.

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.

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 rotates the polygon mirror 51. The motor 52 is fixed to the frame F.

The scanning optical system Lo is an optical system that focuses the beam deflected by the deflector 50 onto the surface of the photosensitive drum 200, which serves as an image plane. The scanning optical system Lo is fixed to the 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.

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.

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

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 in the first scanning optical system LoY that is closest to the polygon mirror 51.

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 in the first direction with respect to the polygon mirror 51. The second scanning lens 70Y is the scanning lens in the first scanning optical system LoY that is closest to the image plane.

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.

The first scanning lens 60YM is shared with the first scanning optical system LoY. The second scanning lens 70M and reflecting mirror 81M have the same functions as the second scanning lens 70Y and 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.

The third scanning optical system LoC has a structure that is roughly 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, which have the same functions as the respective components of the second scanning optical system LoM.

The fourth scanning optical system LoK has a structure that is roughly 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, which have the same functions as the respective components of the first scanning optical system LoY.

As shown in Figure 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 incident on the polygon mirror 51. The condenser lens 40 is a lens through which all beams BY, BM, BC, and BK pass, and has a cylindrical entrance surface and a flat exit surface.

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

Beam BM heading toward the second scanning optical system LoM passes through the first scanning lens 60YM, is reflected by mirror 82M and 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. Beam BM is emitted from the second scanning lens 70M at a predetermined angle with respect to the first direction. Beam BM is imaged on the surface of the second photosensitive drum 200M and scanned in the main scanning direction. Similarly, beams BC and BK are 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.

The frame F is made of resin and is integrally molded. 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, the deflector 50 and part of the scanning optical system Lo are disposed within the first recess CP1. Specifically, all components of the scanning optical system Lo except for the reflecting mirrors 81 are disposed within the first recess CP1. As shown in FIG. 2, the coupling lens 20, diaphragm plate 30, and condenser lens 40 (see FIG. 1) are disposed within the second recess CP2.

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.

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 direction is along the first direction. In other words, the first base wall Fb1 and the second base wall Fb2 are walls having a plane that is perpendicular to the first direction.

The second base wall Fb2 is positioned offset to one side in the first direction relative to the first base wall Fb1. As shown in FIG. 5, the deflector 50 and the aforementioned portion 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 a portion of the scanning optical system Lo are positioned on one side in the first direction relative to the first base wall Fb1. As shown in FIG. 2, the semiconductor laser 10, coupling lens 20, and aperture plate 30 are positioned 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 reflecting mirror 81 are also positioned on the other side in the first direction relative to the second base wall Fb2.

The reflecting mirror 81 is positioned 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.

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 recess CP1, CP2.

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.

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.

The third side wall F43 is located on the opposite side of the deflector 50 from the first scanning lens 60YM. 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 portion of the third side wall F43 protrudes from the first base wall Fb1 to one side in the first direction, and another portion protrudes from the second base wall Fb2 to the other side in the first direction.

The fourth side wall F44 is located on the opposite side of the deflector 50 from the first scanning lens 60CK. The fourth side wall F44 is connected to the other ends 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 portion of the fourth side wall F44 protrudes from the first base wall Fb1 to one side in the first direction, and another portion protrudes from the second base wall Fb2 to the other side in the first direction.

As shown in FIG. 2, the scanning optical device 1 further includes a first laser holder H11 and a second laser holder H12 as examples of first holding members, and a lens holder H2 as an example of a second holding member. The first laser holder H11, the second laser holder H12, and the lens holder H2 are made of resin.

The first laser holder H11 is an L-shaped member 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 with 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 here.

The lens holder H2 is a member that holds the second coupling lens 20M and the third coupling lens 20C. Specifically, the lens holder H2 holds the second coupling lens 20M in a position aligned in the first direction relative to the first coupling lens 20Y. The lens holder H2 also holds the third coupling lens 20C in a position aligned in the first direction relative to the fourth coupling lens 20K.

The lens holder H2 is fixed to the second base wall Fb2 of the frame F by a screw N1. The lens holder H2 can be attached to the second base wall Fb2 from the other side in the first direction. The structure of the lens holder H2 will be described in detail later.

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.

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 first seating surface Hf1. The first seating surface Hf1 is a plane perpendicular to the first direction. The first seating surface Hf1 faces the other side of the first direction. As shown in Figure 6 (c), the first portion 111 is positioned with a gap between it and the frame F in the first direction.

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

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.

The third portion 113 extends 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 portion 113 is 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.

As shown in Figures 6(b) and (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.

As shown in FIG. 6(c), the frame F has a first boss F51. The first boss F51 has a cylindrical shape that is convex toward the other side in the third direction. The first boss F51 has a first positioning surface F511 that contacts surface 114A of the first holder positioning portion 114 in the third direction, and a protrusion F512 that fits into hole 114B. The first positioning surface F511 is a surface for positioning the first laser holder H11 in the third direction, which is an example of a first predetermined direction. The protrusion F512 is an example of a first restricting portion and is a part for positioning the first laser holder H11 in the first direction, which is an example of a second predetermined direction, and in the second direction. The protrusion F512 protrudes from the center of the first positioning surface F511.

A hole F513 (see Figure 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 with the screw N. More specifically, the first holder positioning portion 114 is sandwiched between the head of the screw N and the first positioning surface F511 of the first boss F51.

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 first 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 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.

The frame F has a contact rib F52. 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 Figure 7). When the first laser holder H11 is attached to the frame F, the contact rib F52 is positioned within 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.

The 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. The first holding portion 112A and second holding portion 112B are located between the first holder positioning portion 114 and the second holder positioning portion 115 in the first direction. In addition, the aforementioned first portion 111 is located between the first holding portion 112A and the first holder positioning portion 114 in the first direction.

Therefore, when each semiconductor laser 10Y, 10M is attached to the first laser holder H11, the first holder positioning portion 114, first semiconductor laser 10Y, second semiconductor laser 10M, and second holder positioning portion 115 are aligned in this order in the arrangement direction of each semiconductor laser 10Y, 10M. Furthermore, when each semiconductor laser 10Y, 10M is attached to the first laser holder H11, each semiconductor laser 10Y, 10M is positioned between the first holder positioning portion 114 and the second holder positioning portion 115 in the arrangement direction. Furthermore, when each semiconductor laser 10Y, 10M is 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, when each semiconductor laser 10Y, 10M is attached to the first laser holder H11, the first portion 111 is positioned between the first semiconductor laser 10Y and the first holder positioning portion 114 in the arrangement direction.

As shown in FIG. 7, the frame F has two positioning portions F50, each having the first boss F51 and contact rib F52 described above. 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 first boss F51 protrudes from the second base wall Fb2 of the frame F toward the other side in the third direction. The first bosses F51 are arranged at intervals in the second direction.

The second side wall F42 is located on the opposite side of each first boss F51 from the deflector 50 (see Figure 1). The second side wall F42 has openings F421 that expose each aperture stop 31Y, 31M, 31C, 31K and each first boss F51 to the outside.

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.

As shown in FIG. 8, the lens holder H2 has a base portion H21 and a leg portion H22. The base portion H21 has two second seating surfaces Hf21 and Hf22. The two second seating surfaces Hf21 and Hf22 are spaced apart in the second direction. The second seating surface Hf21 on one side in the second direction is a seating surface to which the second coupling lens 20M is fixed with photocurable resin. The second seating surface Hf22 on the other side in the second direction is a seating surface to which the third coupling lens 20C is fixed with photocurable resin. The two second seating surfaces Hf21 and Hf22 are flat surfaces perpendicular to the first direction. The base portion H21 protrudes toward one side in the third direction relative to the leg portion H22. The base portion H21 covers the first coupling lens 20Y and the fourth coupling lens 20K from the other side in the first direction (see FIG. 2).

The leg H22 has a first leg H22A and a second leg H22B. The first leg H22A and the second leg H22B are spaced apart in the second direction. The first leg H22A and the second leg H22B extend from the base H21 to one side in the first direction. In other words, the first leg H22A and the second leg H22B extend from the base H21 toward the opposite side of the second seating surfaces Hf21, Hf22. Furthermore, the first leg H22A and the second leg H22B extend from the base H21 to one side in the first direction, and then extend away from each other.

The two second seating surfaces Hf21, Hf22 are located between the first leg portion H22A and the second leg portion H22B in the second direction. As shown in FIG. 2, the first leg portion H22A and the second leg portion H22B are each fixed to the second base wall Fb2 of the frame F by screws N1.

The first leg H22A and second leg H22B of the lens holder H2 are positioned to straddle the optical paths of the light from the first semiconductor laser 10Y and the fourth semiconductor laser 10K. This allows the light traveling from the first semiconductor laser 10Y to the first coupling lens 20Y and the light traveling from the fourth semiconductor laser 10K to the fourth coupling lens 20K to pass between the first leg H22A and the second leg H22B.

The first leg H22A and the second leg H22B each have a surface H23 for positioning the lens holder H2 in a first direction and a hole H24 for positioning the lens holder H2 in a third direction.

As shown in Figures 9 and 10, the second base wall Fb2 of the frame F has two second positioning surfaces F61 for positioning the lens holder H2 in the first direction and two cylindrical second bosses F62 for positioning the lens holder H2 in the third direction. The second positioning surfaces F61 face the other side of the first direction. When the lens holder H2 is attached to the frame F, the second positioning surfaces F61 come into contact with the surface H23 of the lens holder H2.

The second boss F62 is an example of a second restriction portion and protrudes from the second positioning surface F61 to the other side in the first direction. When the lens holder H2 is attached to the frame F, the second boss F62 fits into the hole H24 of the lens holder H2.

A hole F621 into which the screw N1 is inserted is formed in the center of the tip surface of the second boss F62. When the lens holder H2 is attached to the frame F, the tip of the leg H22 is sandwiched between the head of the screw N1 and the second positioning surface F61 (see Figures 12(a) and (b)).

As shown in FIG. 9, the second boss F62 and the second positioning surface F61 intersect with the first plane PF1, which includes the first positioning surface F511 described above. Specifically, the first plane PF1 is an extension of the first positioning surface F511, is parallel to the first positioning surface F511, and passes through the first positioning surface F511. In this embodiment, the second positioning surface F61 is perpendicular to the first plane PF1. Furthermore, the first plane PF1 passes through the center of the second boss F62.

As shown in FIG. 10, the protrusion F512 of the first boss F51 and the first positioning surface F511 intersect with a second plane PF2 that includes the second positioning surface F61. Specifically, the second plane PF2 is an extension of the second positioning surface F61, is parallel to the second positioning surface F61, and passes through the second positioning surface F61. In this embodiment, the first positioning surface F511 is perpendicular to the second plane PF2. Furthermore, the second plane PF2 passes through the center of the first boss F51.

Next, we will explain the manufacturing method of the scanning optical device 1. In detail, we will explain how to attach the coupling lens 20 to the frame F.

As shown in Figure 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. Then, the first bonding process shown in Figures 11(a) and 11(b) is performed, followed by the attachment process shown in Figures 12(a) and 12(b), and then the second bonding process shown in Figures 12(b) and 12(c).

As shown in Figure 11(a), in the first bonding step, the first coupling lens 20Y is first grasped 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.

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. After that, by moving the jig J in the first, second, and third directions, the position of the first coupling lens 20Y relative to the first semiconductor laser 10Y is adjusted.

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. 11(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.

As shown in Figures 12(a) and 12(b), in the mounting process, the lens holder H2 is mounted to the frame F with screws N1. Mounting of the lens holder H2 and tightening of the screws N1 can be done manually by a worker or by a dedicated machine.

As shown in Figure 12(b), in the second bonding step, first, the second coupling lens 20M is clamped from the second direction by a jig J. Next, uncured photocurable resin P is placed between the second coupling lens 20M and the second seating surface Hf21 of the lens holder H2. Note that the figure shows an example in which the photocurable resin P is applied to the second seating surface Hf21 of the lens holder H2, and then the second coupling lens 20M is brought closer to the second seating surface Hf21.

Next, by moving the jig J to one side in the first direction, the second coupling lens 20M is brought closer to the second seating surface Hf21 from the other side in the first direction, and the photocurable resin P is sandwiched between the second coupling lens 20M and the second seating surface Hf21. After that, by moving the jig J in the first, second, and third directions, the position of the second coupling lens 20M relative to the second semiconductor laser 10M is adjusted.

After adjusting the position, the second coupling lens 20M is adhesively fixed to the second seating surface Hf21 of the lens holder H2 by irradiating the photocurable resin P with light, as shown in Figure 12(c). The third coupling lens 20C is also adhesively fixed to the second seating surface Hf22 of the lens holder H2 using the same method as the second coupling lens 20M.

As described above, the following effects can be obtained in this embodiment.
Since a plurality of coupling lenses 20 can be attached from the same direction, the manufacturing process can be prevented from becoming complicated.

The lens holder H2 has legs H22 extending from the base H21, which prevents the base H21 from interfering with the first coupling lens 20Y.

The two legs H22A and H22B of the lens holder H2 are fixed to the frame F, allowing the second coupling lens 20M to be stably held by the lens holder H2.

The portion that holds the first semiconductor laser 10Y and the first seating surface Hf1 that secures the first coupling lens 20Y are integrated, improving the positional accuracy of the first coupling lens 20Y relative to the first semiconductor laser 10Y.

By intersecting the second boss F62 with the first plane PF1, the second boss F62 and the first positioning surface F511 are positioned at approximately the same position in the third direction, thereby reducing the effects of thermal expansion of each holder H11, H12, and H2 in the third direction.

The frame may also have a first restricting portion that positions the first holding member in a second predetermined direction and a second positioning surface that positions the second holding member in the second predetermined direction, and the first restricting portion may intersect with a second plane that includes the second positioning surface.

The protrusion F512 of the first boss F51 intersects with the second plane PF2, so that the protrusion F512 and the second positioning surface F61 are positioned at approximately the same position in the first direction, thereby reducing the effects of thermal expansion of each holder H11, H12, and H2 in the first direction.

The second coupling lens 20M and the third coupling lens 20C are fixed to the second seating surfaces Hf21 and Hf22 of the lens holder H2, which reduces the number of parts compared to a structure in which the third coupling lens is fixed to a member separate from the member that holds the second coupling lens.

Because the first laser holder H11, second laser holder H12, and lens holder H2 are all made of resin, the linear expansion coefficients of the first laser holder H11, second laser holder H12, and lens holder H2 can be made uniform, which prevents the four coupling lenses 20 from shifting position when the first laser holder H11, second laser holder H12, and lens holder H2 thermally expand. Furthermore, the linear expansion coefficients of the first laser holder H11, second laser holder H12, and lens holder H2 can be used to compensate for changes in the refractive power and diffractive power of the four coupling lenses 20 that occur due to temperature fluctuations.

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

In the above embodiment, the method of fixing the second holding member to the frame is not limited to screws as in the above embodiment, and it may also be fixed by, for example, adhesive or fitting.

The orientation of the first and second seating surfaces is not limited to that of the above embodiment, and the first and second seating surfaces may be, for example, perpendicular to the second direction.

In the above embodiment, the protrusion F512 is used as the first restricting portion and the second boss F62 is used as the second restricting portion, but the present invention is not limited to this, and each restricting portion may be a recess or a hole. Furthermore, the first predetermined direction and the second predetermined direction may be directions different from those in the above embodiment.

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

The number of legs on the second holding member may be one or three or more.

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

The semiconductor laser 10 may be configured to have multiple light-emitting points. This allows multiple light beams from the semiconductor laser 10 to be converted into multiple beams by a single coupling lens 20, and the multiple beams to be imaged on the surface of the photosensitive drum 200 by the corresponding scanning optical system Lo. In this configuration, the beams BY, BM, BC, and BK in the above embodiment each include multiple beams.

The elements described in the above embodiments and variations may be implemented in any combination.

1 Scanning optical device 10Y First semiconductor laser 10M Second semiconductor laser 20Y First coupling lens 20M Second coupling lens 50 Deflector 51 Polygon mirror F Frame H2 Lens holder H11 First laser holder Hf1 First seating surface Hf21 Second seating surface X1 Rotation axis

Claims (12)

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 deflector having a polygon mirror that deflects the beam from the first coupling lens and the beam from the second coupling lens;
a frame to which the deflector is fixed;
a first holding member that has a first seating 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 having a second seating surface to which the second coupling lens is fixed by a 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 is
a base portion having the second seating surface;
a leg portion extending from the base portion toward an opposite side of the second seating surface,
a second coupling lens held at a position aligned with the first coupling lens in the direction of the rotation axis, and the legs fixed to the frame; A scanning optical device as described in claim 1, wherein the first seating surface and the second seating surface are flat surfaces perpendicular to the direction of the rotation axis. The leg portion is
A first leg;
a second leg portion spaced from the first leg portion in a direction perpendicular to the optical axis direction of the first semiconductor laser and the rotation axis direction,
3. The optical scanning device according to claim 1 , wherein light traveling from the first semiconductor laser to the first coupling lens passes between the first leg and the second leg. The first holding member is
a first portion having the first seating surface;
4. 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. 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 deflector having a polygon mirror that deflects the beam from the first coupling lens and the beam from the second coupling lens;
a frame to which the deflector is fixed;
a first holding member that has a first seating 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 having a second seating surface to which the second coupling lens is fixed by a 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 frame;
The frame is
a first positioning surface that positions the first holding member in a first predetermined direction;
a second restricting portion that positions the second holding member in the first predetermined direction,
The scanning optical device, wherein the second restricting portion intersects with a first plane including the first positioning surface. 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 deflector having a polygon mirror that deflects the beam from the first coupling lens and the beam from the second coupling lens;
a frame to which the deflector is fixed;
a first holding member that has a first seating 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 having a second seating surface to which the second coupling lens is fixed by a 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 frame;
The frame is
a first restricting portion that positions the first holding member in a second predetermined direction;
a second positioning surface that positions the second holding member in the second predetermined direction,
The scanning optical device, wherein the first restricting portion intersects with a second plane including the second positioning surface. 7. The scanning optical device according to claim 1 , wherein the second holding member is fixed to the frame with a screw. 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 deflector having a polygon mirror that deflects the beam from the first coupling lens and the beam from the second coupling lens;
a frame to which the deflector is fixed;
a first holding member that has a first seating 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 having a second seating surface to which the second coupling lens is fixed by a 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 frame;
a third semiconductor laser arranged next to the second semiconductor laser in a direction perpendicular to the optical axis direction of the first semiconductor laser and the direction of the rotation axis;
a fourth semiconductor laser aligned with the first semiconductor laser in the orthogonal direction and aligned with the third semiconductor laser in the rotation axis direction;
a third coupling lens that converts the light from the third semiconductor laser into a beam;
a fourth coupling lens that converts the light from the fourth semiconductor laser into a beam,
The scanning optical device is characterized in that the third coupling lens is fixed to the second seating surface with a photocurable resin. 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 deflector having a polygon mirror that deflects the beam from the first coupling lens and the beam from the second coupling lens;
a frame to which the deflector is fixed;
a first holding member having a first seating surface to which the first coupling lens is fixed, the first holding member holding the first coupling lens;
a second holding member having a second seating surface to which the second coupling lens is fixed and holding 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 has a base portion having the second seating surface and a leg portion extending from the base portion toward an opposite side of the second seating surface, holds the second coupling lens at a position aligned with the first coupling lens in the rotation axis direction, and the leg portion is fixed to the frame,
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;
an attachment step of attaching the leg portion of the second holding member to the frame;
a second bonding step of adjusting the position of the second coupling lens with respect to the second semiconductor laser, and bonding and fixing the second coupling lens to the second seating surface of the second holding member. 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 coupling lens and the second seating surface;
10. The method for manufacturing a scanning optical device according to claim 9 , wherein after adjusting the position of the second coupling lens, the second coupling lens is adhesively fixed to the second seating surface by applying light to a photocurable resin. 11. The method for manufacturing a scanning optical device according to claim 9, 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. 12. The method for manufacturing a scanning optical device according to claim 11 , wherein the position of the second coupling lens is adjusted by sandwiching the second coupling lens with the jig in the orthogonal direction.