JP7823376B2 - Scanning optical device and method for manufacturing the same - Google Patents

Description

The present invention relates to a scanning optical device in which an aperture stop is formed integrally with a frame, and a method for manufacturing a scanning optical device.

Conventionally, there is known a scanning optical device in which the aperture diaphragm, which determines the size of the beam incident on the polygon mirror, is formed integrally with the frame of the scanning optical device (see Patent Document 1). With this technology, the aperture diaphragm is formed integrally with the frame by sliding a nest for forming the aperture diaphragm in a direction perpendicular to the opening and closing direction of the mold that forms the frame.

Japanese Patent Application Laid-Open No. 2005-202039

However, in conventional technology, the insert only forms the aperture stop, which means that there is a problem in that the positioning accuracy between the positioning portion of the frame that positions the semiconductor laser and the aperture stop is not good.

The present invention aims to improve the positioning accuracy between the positioning unit for positioning the semiconductor laser and the aperture stop.

In order to solve the above problem, the scanning optical device of the present invention comprises a semiconductor laser that emits light, a coupling lens that converts the light from the semiconductor laser into a beam, a deflector having a polygon mirror that deflects the beam from the coupling lens, a resin frame to which the deflector is fixed, a laser holder that holds the semiconductor laser, an aperture plate formed integrally with the frame and having an aperture diaphragm through which the beam passes, and a positioning portion formed integrally with the frame and having a shape that is convex or concave in the optical axis direction of the semiconductor laser, for positioning the laser holder.
When no other members are attached to the frame, the aperture stop and the positioning portion are visible from the optical axis direction.

With this configuration, the aperture stop and positioning portion can be formed using the same insert, improving the positioning accuracy of the aperture stop and positioning portion.

Furthermore, the aperture stop and the positioning portion may be aligned on a straight line along the rotation axis of the polygon mirror when viewed from the optical axis direction.

Furthermore, the positioning portion may have a first contact portion that contacts the laser holder in the optical axis direction, and a second contact portion that contacts the laser holder in an orthogonal direction that is orthogonal to the optical axis direction and the rotational axis direction of the polygon mirror, and the aperture stop may be located between the first contact portion and the second contact portion in the rotational axis direction.

The first contact portion may also be a boss into whose center a screw is inserted.

Furthermore, the laser holder may hold multiple semiconductor lasers, and the aperture plate may have multiple aperture stops corresponding to the number of semiconductor lasers.

The optical system may further include a condenser lens disposed between the aperture stop and the polygon mirror for condensing the beam from the coupling lens onto the polygon mirror in the sub-scanning direction, and the aperture forming the aperture stop may have a smaller opening closer to the condenser lens than the opening farther from the condenser lens.

With this configuration, the size of the aperture stop, which is the opening closest to the focusing lens, can be set to the standard size.

The laser holder may also hold the coupling lens.

The frame may also have a side wall located on the opposite side of the positioning unit from the deflector, and the side wall may have an opening for exposing the aperture stop and the positioning unit to the outside.

With this configuration, the side walls increase the rigidity of the frame, and the aperture stop and positioning portion can be formed in the same insert.

In addition, the manufacturing method of a scanning optical device according to the present invention is a manufacturing method of a scanning optical device comprising a semiconductor laser that emits light, a coupling lens that converts the light from the semiconductor laser into a beam, a deflector having a polygon mirror that deflects the beam from the coupling lens, a resin frame to which the deflector is fixed, a laser holder that holds the semiconductor laser, an aperture plate formed integrally with the frame and having an aperture diaphragm through which the beam passes, and a positioning portion formed integrally with the frame and positioning the laser holder with a shape that is convex or concave in the optical axis direction of the semiconductor laser, wherein the aperture diaphragm and the positioning portion are visible from the optical axis direction.
In a method for manufacturing a scanning optical device, the frame is injection molded using a molding die that integrally has a first molding surface that forms the aperture stop and a second molding surface that forms the positioning portion, thereby forming the aperture stop and the positioning portion integrally with the frame.

With this manufacturing method, the aperture stop and positioning portion are formed using the same insert, improving the positioning accuracy of the aperture stop and positioning portion.

The manufacturing method may also include the steps of: forming the frame by injecting resin into an injection molding die having a first die that forms one surface of the frame in the direction of the rotation axis of the polygon mirror, a second die that forms the other surface of the frame in the direction of the rotation axis, and the insert; after forming the frame, moving the first die or the second die in the direction of the rotation axis to separate it from the frame; and after forming the frame, moving the insert in the optical axis direction to separate it from the frame.

This invention can improve the positioning accuracy between the positioning unit for positioning the semiconductor laser and the aperture stop.

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. 4 is a cross-sectional view taken along line IV-IV of FIG. 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 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. 4A is a perspective view showing a first lens holder, and FIG. 4B is a diagram showing the relationship between light from a first semiconductor laser and the first lens holder. 10A to 10D are diagrams showing a method for attaching a coupling lens to a frame. FIG. 10 is a perspective view showing the relationship between the insert and the frame. FIG. 4 is a cross-sectional view showing the state in which the frame has been injection molded using a mold.

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 first lens holder H21 and a second lens holder H22 as examples of second holding members. 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.

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 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 with 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 it holds and the fixed destination are changed to the second laser holder H12, and therefore a description thereof will be omitted.

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 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 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.

The second seating surface Hf2 is a seating surface 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 surface Hf2 is located on the other side in the first direction than the first seating surface Hf1.

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 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.

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 contact surface F511 of the 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 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 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 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 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.

The second side wall F42 is located on the opposite side of the bosses F51 from the deflector 50 (see Figure 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.

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 a result, as shown in FIG. 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. When viewed 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.

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. 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.

As shown in an exaggerated manner in Figure 8(b), the aperture 32 forming the aperture stop 31 has a smaller opening on the side closer to the condenser lens 40 than on the side farther from the condenser lens 40. Note that the aperture stop 31 is the opening on the side of the hole 32 closer to the condenser lens 40.

As shown in FIG. 9(a), the first lens holder H21 has a lens mounting portion 211 and a leg portion 212. The lens mounting portion 211 is the portion where the second coupling lens 20M is attached. The lens mounting portion 211 is cylindrical, and the second coupling lens 20M is attached by fitting to one end of the lens mounting portion 211 on one side in the third direction. The lens mounting portion 211 protrudes on one side in the third direction relative to the leg portion 212.

The leg 212 has a first leg 212A and a second leg 212B. The first leg 212A and the second leg 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 212 extends from the lens mounting portion 211 toward the second seating surface Hf2. The first leg 212A and the second leg 212B are spaced apart in the second direction. The first leg 212A and the second leg 212B are each fixed to the second seating surface Hf2 by photocurable resin.

The first leg 212A and second leg 212B of the first lens holder H21 are positioned to straddle the optical path of the light from the first semiconductor laser 10Y. This allows the light traveling from the first semiconductor laser 10Y to the first coupling lens 20Y to pass between the first leg 212A and the second leg 212B.

Next, we will explain the manufacturing method of the scanning optical device 1. First, we will explain how to attach the coupling lens 20 to the frame F, and finally we will explain how to mold 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 10(a) and 10(b) is performed, followed by the second bonding process shown in Figures 10(c) and 10(d).

As shown in Figure 10(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. 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.

As shown in Figure 10(c), in the second bonding step, first, the first lens holder H21, which is 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.

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. 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, light is applied to the photocurable resin P, adhesively fixing the first lens holder H21 to the second seating surface Hf2 of the first laser holder H11, as shown in FIG. 10(d). At this time, the light for curing the photocurable resin P can be applied to the photocurable resin P through the transparent first lens holder H21, ensuring that the entire photocurable resin P is 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.

As shown in Figure 12, in the method for 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 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.

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.

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 smaller opening on the side of the holes 32 closer to the condenser lens 40, and also makes it easier to move the insert M3 in the third direction away from the frame F.

The second printing surface M32 is a surface for forming 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 two contact ribs F52 (see Figure 8). The second printing surface M33 has two recesses M331 for forming the two contact ribs F52.

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 mold M1, a second mold M2, and a core M3 are combined.

In the second step, after the frame F is formed, at least one of the first mold M1 and the second mold M2 is moved in the first direction and separated from the frame F. In the third step, after the frame F is formed, the insert M3 is moved in the third direction and separated from the frame F. By going through the above steps, each aperture stop 31 and the positioning portion F50 can be formed integrally with the frame F.

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, preventing the manufacturing process from becoming complicated.

The first lens holder H21 has legs 212 extending from the lens mounting portion 211, which prevents the lens mounting portion 211 from interfering with the first coupling lens 20Y.

The two legs 212A and 212B of the first lens holder H21 are fixed to the first laser holder H11, allowing the second coupling lens 20M to be stably held by the first lens holder H21.

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.

The second part 112 that holds the first semiconductor laser 10Y and the seating surface Hf 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 making both the first laser holder H11 and the first lens holder H21 out of resin, the linear expansion coefficients of the first laser holder H11 and the first lens holder H21 can be made the same, which prevents the first coupling lens 20Y and the second coupling lens 20M from shifting position when the first laser holder H11 and the first lens holder H21 thermally expand. Furthermore, by utilizing the linear expansion coefficients of the first laser holder H11 and the first lens holder H21, a configuration can be created 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.

Since each holder positioning unit 114, 115 and each semiconductor laser 10Y, 10M are aligned in the array direction, tolerance management is easy.

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 a single first laser holder H11.

Because the frame F has a boss F51 that contacts 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.

The frame F has a contact rib F52 that contacts the second holder positioning portion 115 in the second direction, preventing the first laser holder H11 from rotating relative to the frame F.

The first coupling lens 20Y is fixed to the seating surface Hf by photocurable resin. After adjusting the first coupling lens 20Y relative to the first semiconductor laser 10Y, the first coupling lens 20Y can be fixed to the seating surface Hf by irradiating the photocurable resin with light.

Since the first portion 111 is positioned with a gap between it and the frame F in the first direction, the seating surface Hf is not affected by the tolerances between the frame F and the first laser holder H11.

Because 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 setting range of the linear expansion coefficient can be widened.

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

The hole 32 that forms 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 the size of the aperture stop 31, which is the opening closest to the condenser lens 40, can be set to the standard size.

By providing the second side wall F42, the rigidity of the frame F can be increased, and by forming an 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.

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 laser holder holds two semiconductor lasers, but the present invention is not limited to this. For example, the number of semiconductor lasers held by the laser holder may be one or three or more. Furthermore, the laser holder does not need to hold a coupling lens.

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.

In the above embodiment, the second holding member is fixed to the seating surface of the first holding member using 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 using photocurable resin. Furthermore, the number of legs of 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.

In the above embodiment, the first lens holder and the second lens holder are made of transparent resin, but the present invention is not limited to this, and it is possible to use materials other than transparent resin that allow light to pass through to harden the photocurable resin. Furthermore, 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.

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 also have a concave shape in the optical axis direction.

In the above embodiment, the first contact portion is a boss and a hole for fitting the boss is formed in the first holder positioning portion, but the present invention is not limited to this. The first holder positioning portion may be a boss and a hole for fitting the boss may be formed in the first contact portion.

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.

REFERENCE SIGNS LIST 1 scanning optical device 10 semiconductor laser 20 coupling lens 30 diaphragm plate 31 aperture diaphragm 50 deflector 51 polygon mirror F frame F50 positioning portion H11 first laser holder H12 second laser holder

Claims (8)

a semiconductor laser that emits light;
a coupling lens that converts light from the semiconductor laser into a beam;
a deflector having a polygon mirror that deflects the beam from the coupling lens;
a resin frame to which the deflector is fixed;
a laser holder for holding the semiconductor laser;
an aperture plate formed integrally with the frame and having an aperture stop through which the beam passes;
a positioning portion that is formed integrally with the frame and has a convex or concave shape in the optical axis direction of the semiconductor laser, and that positions the laser holder;
When no other members are attached to the frame, the aperture stop and the positioning portion are visible from the optical axis direction,
the aperture stop and the positioning portion are aligned on a straight line along the rotation axis direction of the polygon mirror when viewed from the optical axis direction,
The positioning unit is
a first contact portion that comes into contact with the laser holder in the optical axis direction;
a second contact portion that comes into contact with the laser holder in a direction perpendicular to the optical axis direction and the rotation axis direction of the polygon mirror,
The scanning optical device according to claim 1, wherein the aperture stop is located between the first contact portion and the second contact portion in the direction of the rotation axis . 2. The scanning optical device according to claim 1 , wherein the first contact portion is a boss into the center of which a screw is inserted. the laser holder holds a plurality of semiconductor lasers;
3. The scanning optical device according to claim 1 , wherein the diaphragm plate has a plurality of aperture diaphragms, the number of which corresponds to a number of semiconductor lasers. a condenser lens disposed between the aperture stop and the polygon mirror, for condensing the beam from the coupling lens onto the polygon mirror in the sub-scanning direction;
4. The scanning optical device according to claim 1 , wherein the aperture forming the aperture stop has an opening closer to the condenser lens that is smaller than an opening farther from the condenser lens. 5. The optical scanning device according to claim 1 , wherein the laser holder holds the coupling lens. a semiconductor laser that emits light;
a coupling lens that converts light from the semiconductor laser into a beam;
a deflector having a polygon mirror that deflects the beam from the coupling lens;
a resin frame to which the deflector is fixed;
a laser holder for holding the semiconductor laser;
an aperture plate formed integrally with the frame and having an aperture stop through which the beam passes;
a positioning portion that is formed integrally with the frame and has a convex or concave shape in the optical axis direction of the semiconductor laser, and that positions the laser holder;
When no other members are attached to the frame, the aperture stop and the positioning portion are visible from the optical axis direction,
the frame has a side wall located on the opposite side of the positioning portion from the deflector,
The side wall has an opening for exposing the aperture stop and the positioning unit to the outside. a semiconductor laser that emits light;
a coupling lens that converts light from the semiconductor laser into a beam;
a deflector having a polygon mirror that deflects the beam from the coupling lens;
a resin frame to which the deflector is fixed;
a laser holder for holding the semiconductor laser;
an aperture plate formed integrally with the frame and having an aperture stop through which the beam passes;
a positioning portion that is formed integrally with the frame and has a convex or concave shape in the optical axis direction of the semiconductor laser, and that positions the laser holder;
A method for manufacturing a scanning optical device, wherein the aperture stop and the positioning portion are visible from the optical axis direction, comprising:
A method for manufacturing a scanning optical device, characterized in that the aperture stop and the positioning portion are formed integrally with the frame by injection molding the frame using a molding die that integrally has a first molding surface that forms the aperture stop and a second molding surface that forms the positioning portion.
forming the frame by injecting resin into an injection molding die having a first die that forms one surface of the frame in the rotation axis direction of the polygon mirror, a second die that forms the other surface of the frame in the rotation axis direction, and the insert;
a step of moving the first mold or the second mold in the direction of the rotation axis to separate it from the frame after the frame is formed;
8. The method for manufacturing a scanning optical device according to claim 7 , further comprising the step of moving the insert in the optical axis direction to separate it from the frame after forming the frame.