Manufacturing method of scanning optical device

Abstract

To prevent a beam passage position of a scan lens through which a beam last passes from being displaced from a preset range.SOLUTION: A manufacturing method for scanning optical device includes a mounting step, an X-directional adjustment step and a fixing step. The mounting step includes mounting a deflector with a polygon mirror, a first scan lens and a second scan lens 70 to a frame. The X-directional adjustment step includes, after the mounting step, adjusting both an incident angle of a beam B emitted from a light source in a sub-scanning direction with respect to a mirror surface of the polygon mirror, and an angle of a reflection mirror 81, thereby adjusting the position of the beam B on the scanned surface in the sub-scanning direction and the position of the beam on the second scan lens 70 in the sub-scanning direction. The fixing step includes, after the X-directional adjustment step, fixing an incident angle of the beam emitted from the light source with respect to the mirror surface of the polygon mirror in the sub-scanning direction and an angle of the reflection mirror 81.SELECTED DRAWING: Figure 16

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a scanning optical device. [Background technology]

[0002] Conventionally, a method for manufacturing a scanning optical device is known in which the angle of a reflecting mirror in a scanning optical system is adjusted in order to adjust the incident position on a surface to be scanned in the sub-scanning direction (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-248179 A Summary of the Invention [Problem to be solved by the invention]

[0004] Here, in Patent Document 1, the angle of the reflecting mirror behind the final scanning lens through which the beam passes last is adjusted. Therefore, even if the angle of the reflecting mirror is adjusted, the beam passing position in the final scanning lens does not change. However, in a scanning optical device without a reflecting mirror behind the final scanning lens, it is necessary to adjust the reflecting mirror in front of the final scanning lens in order to adjust the exposure position in the sub-scanning direction to a predetermined position. Therefore, when the angle of the reflecting mirror is adjusted, the beam passing position in the final scanning lens changes. As a result, it is assumed that the beam passing position in the final scanning lens may deviate from the set range. If the beam passing position in the final scanning lens deviates from the set range, the imaging state on the scanned surface may deteriorate.

[0005] Therefore, an object of the present invention is to prevent the passing position of the beam in the scanning lens through which the beam last passes from being outside a set range. [Means for solving the problem]

[0006] In order to achieve the above object, a manufacturing method for a scanning optical device according to the present invention includes an attachment step, an X-direction adjustment step, and a fixing step. The scanning optical system includes a light source, a deflector, a scanning optical system, and a frame. The light source includes a semiconductor laser and a coupling lens that converts light emitted from the semiconductor laser into a beam. The deflector includes a polygon mirror and deflects the beam emitted from the light source in the main scanning direction. The scanning optical system forms an image of the beam deflected by the deflector on a surface to be scanned. The scanning optical system includes a first scanning lens, a second scanning lens disposed downstream of the first scanning lens in the traveling direction of the beam, and a reflecting mirror disposed between the first scanning lens and the second scanning lens in the traveling direction of the beam. The light source, the deflector, and the scanning optical system are attached to the frame. The mounting step is a step of mounting the deflector, the first scan lens, and the second scan lens on a frame. The X-direction adjustment process is a process performed after the installation process to adjust the position of the beam in the sub-scanning direction on the scanned surface and the position of the beam in the sub-scanning direction on the second scanning lens by adjusting both the incident angle of the beam from the light source to the mirror surface of the polygon mirror and the angle of the reflecting mirror. The fixing step is a step of fixing the incident angle of the beam from the light source to the mirror surface of the polygon mirror in the sub-scanning direction and the angle of the reflecting mirror after the X-direction adjustment step.

[0007] In the X-direction adjustment process, by adjusting both the incident angle of the beam from the light source to the mirror surface of the polygon mirror in the sub-scanning direction and the angle of the reflecting mirror, it is possible to prevent the passing position of the beam in the scanning lens that the beam finally passes through from being out of the set range, thereby preventing the imaging state on the scanned surface from deteriorating.

[0008] Furthermore, in the X-direction adjustment step, when adjusting the angle of incidence of the beam from the light source in the sub-scanning direction with respect to the mirror surface of the polygon mirror, a coupling lens may be moved in the sub-scanning direction.

[0009] In the X-direction adjustment process, the coupling lens is moved in the sub-scanning direction, which makes it easy to adjust the incident angle of the beam in the sub-scanning direction with respect to the mirror surface of the polygon mirror.

[0010] In the fixing step, the position of the coupling lens relative to the frame may be fixed.

[0011] In the fixing step, the position of the coupling lens in the sub-scanning direction is fixed relative to the frame, whereby the incident angle of the beam with respect to the mirror surface of the polygon mirror in the sub-scanning direction is fixed.

[0012] Furthermore, after the mounting step and before the X-direction adjustment step, a Y-direction adjustment step may be included in which the coupling lens is moved in the main scanning direction to adjust the angle of incidence in the main scanning direction to the deflector.

[0013] By having the Y-direction adjustment step after the mounting step, the X-direction adjustment step can be performed after determining the angle of incidence in the main scanning direction on the mirror surface of the polygon mirror.

[0014] Furthermore, after the X-direction adjustment step, a Z-direction adjustment step may be included in which the coupling lens is moved in the beam traveling direction to adjust the focal position.

[0015] By having the Z-direction adjustment process after the X-direction adjustment process, even if the focal position moves due to the X-direction adjustment process, the focal position can be aligned with the surface to be scanned by making adjustments in the subsequent process.

[0016] In addition, in the X-direction adjustment step, a first sensor that detects the position of the beam in the sub-scanning direction may be disposed at a position corresponding to the surface to be scanned. In the X-direction adjustment step, a second sensor that detects the position of the beam in the sub-scanning direction may be disposed between the reflecting mirror and the surface to be scanned. In the X-direction adjustment step, adjustment may be made based on the detection results of the first sensor and the second sensor.

[0017] By disposing the second sensor between the reflecting mirror and the scanned surface instead of on the scanned surface, the position and direction of the beam can be detected based on the detection result of the first sensor and the detection result of the second sensor disposed at a different position from the first sensor. Therefore, the first sensor and the second sensor can detect not only the imaging position but also the passing position of the beam on the second scanning lens, so that it is possible to prevent the passing position of the beam on the second scanning lens from deviating from the set range.

[0018] Also, the second sensor may be disposed between the second scanning lens and the surface to be scanned.

[0019] By disposing the second sensor between the second scanning lens and the surface to be scanned, the position of the beam can be detected even if the distance between the reflecting mirror and the second scanning lens is narrow.

[0020] Also, the second sensor may be disposed in the center in the main scanning direction, and the first sensor may be disposed at at least two positions sandwiching the second sensor in the main scanning direction.

[0021] By disposing the first sensors in at least two locations, it is possible to detect with high precision the inclination of the scanning line on the surface to be scanned with respect to the main scanning direction. Effect of the Invention

[0022] According to the present invention, it is possible to prevent the passing position of the beam in the scanning lens through which the beam last passes from being outside a set range. [Brief description of the drawings]

[0023] [Figure 1] 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. [Diagram 2] FIG. 2 is a perspective view showing a structure around a coupling lens. [Diagram 3] 2 is a perspective view of the scanning optical device as seen from one side in a first direction. FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. [Diagram 5] FIG. 2 is a cross-sectional view of FIG. 1 . [Figure 6] 1A is a perspective view showing the first laser holder, FIG. 1B is a rear view of the first laser holder as seen from the other side in the third direction, and FIG. 1C is a side view showing the first laser holder with a portion thereof cut away. [Figure 7] FIG. 4 is an exploded perspective view showing the relationship between a frame and a laser holder. [Figure 8] FIG. 2A is a perspective view showing a first lens holder, and FIG. 2B is a diagram showing the relationship between the light from a first semiconductor laser and the first lens holder. [Figure 9] 1A to 1D are diagrams showing a method for attaching a coupling lens to a frame. [Figure 10] 4 is a cross-sectional view showing a structure for mounting the reflecting mirror to a frame. FIG. [Figure 11] 5 is a flowchart showing a method for manufacturing a scanning optical device according to the embodiment. [Figure 12] FIG. 11 is a perspective view showing a Y-direction adjustment step. [Figure 13] FIG. 11 is a perspective view showing an X-direction adjustment step. [Figure 14] FIG. 11 is a perspective view showing a Z-direction adjustment step. [Figure 15] 11A to 11C are diagrams illustrating the principle of a sensor used in a Z-direction adjustment process. [Figure 16] 13A to 13C are diagrams illustrating a procedure for adjusting a beam in an X-direction adjustment step. [Figure 17] 13A and 13B are diagrams illustrating a procedure for adjusting a beam in an X-direction adjustment step in a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] As shown in FIG. 1 to FIG. 3, the scanning optical device 1 includes a frame F, an incident optical system Li, a deflector 50, and a scanning optical system Lo. The scanning optical device 1 is applied to an electrophotographic image forming apparatus. In the following description, a direction along the rotation axis X1 of the polygon mirror 51 shown in FIG. 3 is referred to as a "first direction". A direction perpendicular to the first direction, in which the polygon mirror 51 and the first scanning lens 60 shown in FIG. 3 are aligned, is referred to as a "second direction". A direction perpendicular to the first direction and the second direction is referred to as a "third direction". The third direction corresponds to the optical axis direction of the first semiconductor laser 10Y and the main scanning direction in the scanning optical system Lo, which will be described later. The arrows indicating each direction in the drawings indicate "one side" in each direction.

[0025] As shown in FIG. 2, the incidence optical system Li includes four semiconductor lasers 10, four coupling lenses 20, an aperture plate 30, and a condenser lens 40 (see FIG. 1).

[0026] The semiconductor laser 10 is a device that emits light. Four semiconductor lasers 10 are provided corresponding to four photosensitive drums 200 (see FIG. 5) that are scanned and exposed by the scanning optical device 1. A toner image of a different color is formed on each photosensitive drum 200.

[0027] In this embodiment, the first color is "yellow (Y)", the second color is "magenta (M)", the third color is "cyan (C)", and the fourth color is "black (K)". In the following description, the names of the components corresponding to the first color may be distinguished by adding "first" to the beginning of the name and adding "Y" to the end of the reference numerals of the components corresponding to the first color. Similarly, the names of the components corresponding to the second, third, and fourth colors may be distinguished by adding "second", "third", and "fourth" to the beginning of the name and adding "M", "C", and "K" to the end of the reference numerals.

[0028] The first semiconductor laser 10Y is arranged in the first direction with a gap between them and the second semiconductor laser 10M. The first semiconductor laser 10Y is located on one side in the first direction with respect to the second semiconductor laser 10M.

[0029] The third semiconductor laser 10C is arranged at an interval from the second semiconductor laser 10M in the second direction. The third semiconductor laser 10C is located on the other side in the second direction from the second semiconductor laser 10M. The fourth semiconductor laser 10K is arranged at an interval from the third semiconductor laser 10C in the first direction, and is arranged at an interval from the first semiconductor laser 10Y in the second direction.

[0030] The coupling lens 20 is a lens that converts the light from the semiconductor laser 10 into a beam. The coupling lenses 20Y, 20M, 20C, and 20K corresponding to each color are arranged at positions facing the corresponding semiconductor lasers 10Y, 10M, 10C, and 10K. The coupling lens 20 is a resin lens having axially symmetric optical surfaces on both the entrance surface and the exit surface, and has refractive power and diffractive power. A pair of the semiconductor laser 10 of each color and the coupling lens 20 constitutes the light source of the present invention.

[0031] 1, the diaphragm plate 30 is a portion having an aperture diaphragm 31 through which the beam from the coupling lens 20 passes, and is formed integrally with the frame F. The diaphragm plate 30 is located between the coupling lens 20 and the condenser lens 40. The diaphragm plate 30 has a plurality of aperture diaphragms 31Y, 31M, 31C, and 31K in number corresponding to the plurality of semiconductor lasers 10Y, 10M, 10C, and 10K.

[0032] 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 to the coupling lens 20. In other words, the condenser lens 40 is disposed between the aperture diaphragm 31 and the polygon mirror 51.

[0033] 3, the deflector 50 has a polygon mirror 51 and a motor 52. The polygon mirror 51 is a mirror that deflects the beam from the condenser lens 40 in the main scanning direction. The polygon mirror 51 has five mirror surfaces that are equidistant from the rotation axis X1. The motor 52 is a motor that rotates the polygon mirror 51. The motor 52 is fixed to the frame F.

[0034] The scanning optical system Lo is an optical system that forms an image of the beam deflected by the deflector 50 on a surface to be scanned. Specifically, the scanning optical system Lo forms an image of the beam deflected by the deflector 50 on the surface of the photosensitive drum 200 as a surface to be scanned. The scanning optical system Lo is fixed to a frame F. As shown in FIG. 5, the scanning optical system Lo has a first scanning optical system LoY corresponding to yellow, a second scanning optical system LoM corresponding to magenta, a third scanning optical system LoC corresponding to cyan, and a fourth scanning optical system LoK corresponding to black.

[0035] The first scanning optical system LoY and the second scanning optical system LoM are disposed 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 disposed 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.

[0036] The first scanning optical system LoY has a first scanning lens 60YM, a second scanning lens 70Y, and a reflecting mirror 81Y.

[0037] 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 scanned surface. The first scanning lens 60YM has an fθ characteristic that makes the light scanned at a constant angular velocity by the deflector 50 move at a constant velocity on the scanned surface. The first scanning lens 60YM is the scanning lens closest to the polygon mirror 51 in the first scanning optical system LoY.

[0038] The reflecting mirror 81Y is a mirror that reflects the beam BY from the first scanning lens 60YM toward the surface to be scanned. The reflecting mirror 81Y is disposed between the first scanning lens 60YM and the second scanning lens 70Y in the traveling direction of the beam BY. 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 surface to be scanned. The second scanning lens 70Y is disposed at a position on one side in the first direction with respect to the polygon mirror 51. The second scanning lens 70Y is the scanning lens of the first scanning optical system LoY that is closest to the surface to be scanned. The second scanning lens 70Y is disposed downstream of the first scanning lens 60YM in the traveling direction of the beam BY.

[0039] 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.

[0040] The first scanning lens 60YM is shared with the first scanning optical system LoY. The second scanning lens 70M and the reflecting mirror 81M have the same functions as the second scanning lens 70Y and the reflecting mirror 81Y of the first scanning optical system LoY. The mirror 82M is a mirror that reflects the beam BM from the first scanning lens 60YM to the reflecting mirror 81M.

[0041] The third scanning optical system LoC has a structure that is generally symmetrical to the second scanning optical system LoM with respect to the rotation axis X1 of the polygon mirror 51. Specifically, the third scanning optical system LoC has a first scanning lens 60CK, a second scanning lens 70C, a reflecting mirror 81C, and a mirror 82C that have the same functions as the respective members of the second scanning optical system LoM.

[0042] The fourth scanning optical system LoK has a structure that is generally symmetrical to the first scanning optical system LoY with respect to the rotation axis X1 of the polygon mirror 51. Specifically, the fourth scanning optical system LoK has a first scanning lens 60CK, a second scanning lens 70K, and a reflecting mirror 81K that have the same functions as the respective members of the first scanning optical system LoY.

[0043] 4, the light emitted from each of the semiconductor lasers 10Y, 10M, 10C, and 10K is converted into beams BY, BM, BC, and BK by passing through the corresponding coupling lenses 20Y, 20M, 20C, and 20K. The beams BY, BM, BC, and BK pass through the corresponding aperture stops 31Y, 31M, 31C, and 31K of the diaphragm plate 30, then pass through the condenser lens 40 and are incident on the polygon mirror 51. The condenser lens 40 is a lens through which the beams BY, BM, BC, and BK pass in common, and has a cylindrical entrance surface and a flat exit surface.

[0044] 5, the polygon mirror 51 deflects the beams BY, BM, BC, and BK emitted from the light source in the main scanning direction toward the corresponding scanning optical systems LoY, LoM, LoC, and LoK. The beam BY toward the first scanning optical system LoY passes through a first scanning lens 60YM, is reflected by a reflecting mirror 81Y, passes through a second scanning lens 70Y, and is imaged on the surface of the first photosensitive drum 200Y.

[0045] The beam BM heading toward the second scanning optical system LoM passes through the first scanning lens 60YM, is reflected by the mirror 82M and the reflecting mirror 81M, passes through the second scanning lens 70M, and is imaged on the surface of the second photosensitive drum 200M. Similarly, the beams BC and BK are imaged on the surfaces of the corresponding photosensitive drums 200C and 200K by the corresponding scanning optical systems LoC and LoK.

[0046] The frame F is made of resin and is integrally formed by molding. The semiconductor laser 10, the coupling lens 20, the condenser lens 40, the polygon mirror 51, and the scanning optical system Lo are attached to the frame F. 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 a part of the scanning optical system Lo are arranged in the first recess CP1. Specifically, the members of the scanning optical system Lo except for the reflection mirrors 81 are arranged in the first recess CP1. As shown in FIG. 2, the coupling lens 20, the aperture plate 30, and the condenser lens 40 (see FIG. 1) are arranged in the second recess CP2.

[0047] 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.

[0048] The reflection mirror 81 is disposed near the first base wall Fb1 and is exposed to the other side in the first direction relative to the first base wall Fb1. The reflection mirror 81 is exposed to 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.

[0049] 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 which form a substantially rectangular frame surrounding each of the recesses CP1 and CP2.

[0050] 2, the scanning optical device 1 further includes a first laser holder H11, a second laser holder H12, a first lens holder H21, and a second lens holder H22. 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 transmissible to light for curing the photocurable resin.

[0051] 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 by a photocurable resin. The first coupling lens 20Y can be attached to the first laser holder H11 from the other side in the first direction. The first laser holder H11 is fixed to the frame F. The structure of the first laser holder H11 will be described in detail later. 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.

[0052] The first lens holder H21 is a member that holds the second coupling lens 20M at a position aligned with the first coupling lens 20Y in the first direction. The first lens holder H21 is fixed to the first laser holder H11 by a photocurable resin. The first lens holder H21 can be attached to the first laser holder H11 from the other side in the first direction. The structure of the first lens holder H21 will be described in detail later. Note that the second lens holder H22 is configured similarly to the first lens holder H21, except that the object to be held and the fixed destination are changed to the second laser holder H12, and other points are omitted from the description.

[0053] 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.

[0054] The first portion 111 is a plate-like portion whose thickness direction is along the first direction, and whose dimension in the third direction is larger 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 planes perpendicular to the first direction. The first seating surface Hf1 and the second seating surface Hf2 face the other side of the first direction. As shown in FIG. 6(c), the first portion 111 is disposed with a gap between it and the frame F in the first direction.

[0055] The first seating surface Hf1 is a seating surface to which the first coupling lens 20Y is fixed by a photocurable resin. The first seating surface Hf1 is located at one end of the first portion 111 in the third direction.

[0056] The second seating surface Hf2 is a seating surface to which the first lens holder H21 is fixed by a photocurable resin. The second seating surface Hf2 is provided at each end in the second direction of the first portion 111. The second seating surface Hf2 is located on the other side in the first direction than the first seating surface Hf1.

[0057] 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 penetrating in the third direction and a pair of semi-cylindrical ribs extending from the periphery of the hole to the other side in the third direction. The semiconductor laser 10 is held by being pressed between the pair of ribs.

[0058] 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.

[0059] As shown in FIGS. 6(b) and 6(c), the first holder positioning portion 114 is a portion for positioning the first laser holder H11 with respect 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 the two third portions 113 and is 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 direction and the second direction.

[0060] As shown in Fig. 6(c), the frame F has a boss F51. 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.

[0061] A hole F513 (see FIG. 7) into which a screw N is inserted is formed at the center of the tip surface of the protrusion F512. The first holder positioning portion 114 is fixed to the frame F in the third direction by the screw N. More specifically, the first holder positioning portion 114 is sandwiched between the head of the screw N and the contact surface F511 of the boss F51.

[0062] As shown in FIG. 6(b), the second holder positioning portion 115 is a portion that restricts the first laser holder H11 from rotating about 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 for restricting 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.

[0063] 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 toward the other side in the third direction (see FIG. 7). When the first laser holder H11 is attached to the frame F, the contact rib F52 is inserted in the groove 115A of the second holder positioning portion 115. The contact rib F52 contacts the groove 115A in the second direction. A gap is formed between the second holder positioning portion 115 and the frame F in the first direction to allow thermal expansion to escape.

[0064] As shown in Fig. 7, the frame F has two positioning portions F50 each having the boss F51 and the 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 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.

[0065] As shown in Fig. 8(a), the first lens holder H21 has a lens mounting part 211 and a leg part 212. The lens mounting part 211 is a part where the second coupling lens 20M is attached. The lens mounting part 211 is cylindrical, and the second coupling lens 20M is attached by fitting to one end part in the third direction. The lens mounting part 211 protrudes from the leg part 212 to one side in the third direction.

[0066] 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 part 211 to one side in the first direction. As a result, as shown in FIG. 8(b), in a state in which the first lens holder H21 is attached to the first laser holder H11, the leg 212 extends from the lens mounting part 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 a photocurable resin.

[0067] The first leg 212A and the second leg 212B of the first lens holder H21 are disposed so as 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.

[0068] When the coupling lenses 20 corresponding to yellow and black are attached to the frame F, the coupling lens 20 is held using a jig J that holds the coupling lens 20 from the second direction as shown in FIG. 9(a). The jig J may be configured to hold the coupling lens 20 by holding it from the third direction. Next, an uncured photocurable resin P is placed between the coupling lens 20 and the first seating surface Hf1 of the first laser holder H11. After adjusting the position, the photocurable resin P is irradiated with light to bond and fix the coupling lens 20 to the first seating surface Hf1 of the first laser holder H11 as shown in FIG. 9(b).

[0069] When the coupling lenses 20 corresponding to magenta and cyan are attached to the frame F, as shown in FIG. 9(c), the lens holder H21 holding the coupling lens 20 is sandwiched and held by the jig J from the second direction. The jig J may be configured to sandwich and hold the coupling lens 20 from the third direction. Next, the uncured photocurable resin P is placed between the first lens holder H21 and the second seating surface Hf2 of the first laser holder H11. Next, the photocurable resin P is sandwiched between the first lens holder H21 and the second seating surface Hf2. Then, the jig J is moved in the first direction, the second direction, and the third direction to adjust the position of the second coupling lens 20M relative to the second semiconductor laser 10M. After the position adjustment, the photocurable resin P is irradiated with light, and the first lens holder H21 is adhesively fixed to the second seating surface Hf2 of the first laser holder H11 as shown in FIG. 9(d).

[0070] As shown in FIG. 10, the scanning optical device 1 further includes a support member Fs that is detachable from the frame F having the first recess CP1 and the second recess CP2 described above. The support member Fs is a member that supports the reflecting mirror 81. The support member Fs has a seating surface FsZ that supports the reflecting mirror 81 and allows the angle of the reflecting mirror 81 to be adjusted. The seating surface FsZ has a spherical protrusion Fs1 that can support the reflecting mirror 81 so that the reflecting mirror 81 can be tilted about an axis extending in the third direction. The protrusion Fs1 protrudes toward the reflecting mirror 81 and contacts the reflecting mirror 81 to serve as a fulcrum when adjusting the orientation of the reflecting mirror 81. The orientation of the reflecting mirror 81 relative to the seating surface FsZ is fixed by the photocurable resin P. The photocurable resin P can be, for example, an ultraviolet-curable resin. The reflecting mirror 81 and the support member Fs fixed by the photocurable resin P are prevented from coming off the frame F by a U-shaped leaf spring SP.

[0071] The leaf spring SP is a spring that presses the reflecting mirror 81 towards the seating surface FsZ. The leaf spring SP has an opening SPK through which light that hardens the photocurable resin can pass (see FIG. 1). The frame F has a shape that exposes a portion of the reflecting mirror 81 that overlaps with the seating surface FsZ in the thickness direction (direction perpendicular to the reflecting surface) on the other side in the first direction. This allows the light that passes through the opening SPK to reach the photocurable resin. The reflecting mirror 81 does not have a reflective film that forms a reflective surface at both ends in the third direction.

[0072] For each reflecting mirror 81, one support member Fs and one leaf spring SP are disposed at each end in the longitudinal direction of the reflecting mirror 81. A pair of support members Fs and a pair of leaf springs SP corresponding to one reflecting mirror 81 are provided for each of the four reflecting mirrors 81.

[0073] The frame F has a support surface Fm1 that supports the support member Fs. The support surfaces Fm1 are disposed at positions corresponding to the respective ends of the four reflecting mirrors 81 in the longitudinal direction.

[0074] When attaching the reflecting mirror 81 to the frame F, the photocurable resin P is applied to both sides of the protrusion Fs1 of the support member Fs, and the support member Fs is attached to the support surface Fm1. Then, the reflecting mirror 81 is brought into contact with the protrusion Fs1 of the support member Fs. At this time, the photocurable resin P is arranged in a state of contact with both the support member Fs and the reflecting mirror 81. Then, the leaf spring SP is attached, and the reflecting mirror 81 and the support member Fs are pressed toward the frame F. Next, while the semiconductor laser 10 is emitting light, the reflecting mirror 81 is tilted from the protrusion Fs1 as a starting point while monitoring the position of the beam on the surface to be scanned, thereby adjusting the angle of the reflecting mirror 81. When adjusting the angle of the reflecting mirror 81, the arm AM shown by the two-dot chain line is pressed against the reflecting mirror 81 to move the reflecting mirror 81. After the angle adjustment is completed, the reflecting mirror 81 is fixed to the support member Fs by applying light such as ultraviolet light to the photocurable resin P.

[0075] Next, we will explain the manufacturing method of the scanning optical device 1. In reality, lenses and mirrors corresponding to each color of yellow, magenta, cyan, and black are arranged and their positions are adjusted, but here we will explain the lenses and mirrors corresponding to black as a representative example, and omit the explanations for the other colors.

[0076] As shown in FIG. 11, the manufacturing method of the scanning optical device 1 includes an attachment step (S1), a Y-direction adjustment step (S2), an X-direction adjustment step (S3), a Z-direction adjustment step (S4), and a fixing step (S5).

[0077] The mounting step (S1) is a step of mounting and fixing the semiconductor laser 10, the condenser lens 40, the deflector 50, the first scanning lens 60, and the second scanning lens 70 to a frame F.

[0078] As shown in Fig. 7, to fix the semiconductor laser 10 to the frame F, the laser holders H11 and H12 holding the semiconductor laser 10 are attached to the frame F with screws N. Next, as shown in Fig. 3, the deflector 50, the first scanning lens 60, and the second scanning lens 70 are fixed to the frame F. Note that the order in which the semiconductor laser 10, the deflector 50, the first scanning lens 60, the second scanning lens 70, and the condenser lens 40 are fixed to the frame F is arbitrary.

[0079] The Y-direction adjustment step (S2) is a step performed after the attachment step (S1) and before the X-direction adjustment step (S3). The Y-direction adjustment step (S2) is a step of adjusting the incidence angle of the beam to the deflector 50 in the main scanning direction by disposing the coupling lens 20 between the semiconductor laser 10 and the polygon mirror 51 and moving the coupling lens 20 in the main scanning direction. By disposing the coupling lens 20 on the frame F, a light source that converts the light from the semiconductor laser 10 into a substantially parallel beam is formed.

[0080] 12, when performing the Y-direction adjustment step (S2), the inspection mirror 110 and the light measurement device 120 are placed at predetermined positions. The inspection mirror 110 is placed between the coupling lens 20 and the polygon mirror 51, and reflects the beam B from the coupling lens 20 toward the light measurement device 120. The light measurement device 120 may use an autocollimator that detects the angle of the beam B reflected by the inspection mirror 110. An operator adjusts the angle of incidence in the main scanning direction onto the mirror surface of the polygon mirror 51 based on the detection result of the light measurement device 120. Furthermore, before executing the X-direction adjustment step (S3), a rough adjustment of the angle of the beam B in the sub-scanning direction is performed in the Y-direction adjustment step (S2). Furthermore, before executing the Z-direction adjustment step (S4), a rough adjustment of the focal position of the beam B is performed in the Y-direction adjustment step (S2). This makes it possible to convert the light from the semiconductor laser 10 into a substantially parallel beam. When roughly adjusting the focal position of beam B, light measurement device 120 may use a two-dimensional imaging element capable of measuring the beam diameter, or may use both an autocollimator and a two-dimensional imaging element simultaneously.

[0081] The X-direction adjustment step (S3) is a step performed after the attachment step (S1) and the Y-direction adjustment step (S2). The X-direction adjustment step (S3) adjusts both the incident angle of the beam B in the sub-scanning direction with respect to the mirror surface of the polygon mirror 51 and the angle of the reflecting mirror 81, thereby adjusting the position of the beam B in the sub-scanning direction on the scanned surface and the position in the sub-scanning direction on the second scanning lens 70. In this embodiment, when adjusting the incident angle in the sub-scanning direction from the light source with respect to the mirror surface of the polygon mirror 51, the coupling lens 20 is moved in the sub-scanning direction (X direction).

[0082] 13, when performing the X-direction adjustment step (S3), the condenser lens 40 is fixed to the frame F, and the first sensor 130 and the second sensor 140 are arranged at predetermined positions. The first sensor 130 and the second sensor 140 are sensors that detect the position of the beam B in the sub-scanning direction. In this embodiment, the first sensor 130 and the second sensor 140 are sensors equipped with two-dimensional imaging elements.

[0083] The first sensor 130 is disposed at positions corresponding to both ends in the main scanning direction of the photosensitive drum 200, as indicated by the two-dot chain line. The first sensor 130 is disposed at a position where its detection surface corresponds to the surface to be scanned. The first sensor 130 is disposed at two positions sandwiching the second sensor 140 in the main scanning direction. The first sensor 130 is disposed at a position closer to the end of the scanning range on the surface to be scanned in the main scanning direction than the intermediate position between the center of the scanning range and the end of the scanning range.

[0084] The second sensor 140 is disposed at a position corresponding to the center of the photosensitive drum 200 in the main scanning direction, as indicated by the two-dot chain line. The second sensor 140 is also disposed between the reflecting mirror 81 and the surface to be scanned. More specifically, the second sensor 140 is preferably disposed between the second scanning lens 70 and the surface to be scanned. Note that the closer the detection surface of the second sensor 140 is to the second scanning lens 70, the easier it is to accurately detect the position in the sub-scanning direction where the beam B passes through the second scanning lens 70. For this reason, the detection surface of the second sensor 140 is preferably disposed at a position closer to the second scanning lens 70 than the intermediate position between the second scanning lens 70 and the surface to be scanned.

[0085] Based on the detection results of the first sensor 130 and the second sensor 140, the operator adjusts the position of the beam B in the sub-scanning direction on the surface to be scanned and the position of the beam B in the sub-scanning direction on the second scanning lens 70.

[0086] Specifically, as shown in FIG. 16(a), if the passing position (solid line) of the beam B is deviated from the set passing position (broken line), the position of the beam B in the sub-scanning direction is adjusted by moving both the coupling lens 20 and the reflecting mirror 81 as shown in FIG. 16(a) and (b). In practice, the operator adjusts the coupling lens 20 and the reflecting mirror 81 alternately multiple times based on the detection results of the first sensor 130 and the second sensor 140 to correctly align the position of the beam B in the sub-scanning direction on the scanned surface and the position of the beam B in the sub-scanning direction on the second scanning lens 70. For example, in the state of FIG. 16(a), the position and traveling direction of the beam B from the reflecting mirror 81 toward the scanned surface are calculated based on the detection results of the first sensor 130 and the second sensor 140, and the coupling lens 20 is moved in either direction in the X direction to adjust the optical path of the beam B from the polygon mirror 51 toward the reflecting mirror 81 to approach the designed position (see FIG. 16(b)). Then, by moving the angle of the reflecting mirror 81 so that beam B reaches a predetermined position of the first sensor 130 and a predetermined position of the second sensor 140 from the state shown in Figure 16(b), it is possible to adjust beam B so that it follows the correct optical path as designed, as shown in Figure 16(c).

[0087] The Z-direction adjustment step (S4) is a step performed after the X-direction adjustment step (S3). The Z-direction adjustment step (S4) is a step of adjusting the focal position to the surface to be scanned by moving the coupling lens 20 in the traveling direction of the beam B.

[0088] As shown in Fig. 14, when performing the Z-direction adjustment step (S4), the third sensor 150 is placed at a predetermined position. The third sensor 150 is a sensor that detects the focal position. In this embodiment, the third sensor 150 is a sensor that has a DF unit 155 and a two-dimensional imaging element 150A (see also Fig. 15). The operator adjusts the focal position to the surface to be scanned based on the detection result of the third sensor 150.

[0089] As shown in Fig. 15, the DF unit 155 is a plane parallel glass having a reflective layer forming a half mirror on both the first surface A1 and the second surface A2. In this embodiment, the reflective layer is a dielectric multilayer film having a reflectance of about 99% at the wavelength (780 nm) of the semiconductor laser, which is the light source. When the beam B hits the first surface A1 and the second surface A2, about 99% is reflected and about 1% is transmitted. The DF unit 155 is disposed obliquely with respect to the traveling direction of the beam B.

[0090] Specifically, when the beam B hits the DF unit DF, a part of the beam B passes through the first surface A1 and enters the DF unit 155. The part of the beam B that enters the DF unit 155 is split by the second surface A2 into a passing beam B1 and a reflected beam. The part of the beam reflected by the second surface A2 is reflected by the inner surface of the first surface A1 and reaches the second surface A2 again. The beam that reaches the second surface A2 again is split into a passing beam B2 and a reflected beam. In this way, the beam B is split by the DF unit 155 into a plurality of beams B1, B2, B3, B4, etc. The plurality of beams B1, B2, B3, B4, etc. split by the DF unit 155 each have a different optical path length to the two-dimensional image sensor 150A. Since the optical path lengths of the beams B1, B2, B3, B4, etc. are different from one another, the beam diameters of the beams B1, B2, B3, B4, etc. are different from one another at the two-dimensional imaging element 150A. The operator adjusts the position of the coupling lens 20 in the Z direction so that a specific beam, for example, beam B3, among the beams B1, B2, B3, B4, etc. measured by the third sensor 150 has a sufficiently narrow beam diameter.

[0091] The fixing step (S5) is a step of fixing the position of the coupling lens 20 with respect to the frame F, after the adjustment of the position of the coupling lens 20 in the X direction, Y direction, and Z direction is completed. In this embodiment, after the adjustment of the position of the coupling lens 20 is completed, the photocurable resin P is irradiated with light, thereby fixing the coupling lens 20. The fixing step (S5) is a step of fixing the angle of the reflecting mirror 81 after the adjustment of the angle of the reflecting mirror 81 is completed. In this embodiment, the angle of the reflecting mirror 81 is fixed by irradiating light to the photocurable resin P. Note that since the angle of the reflecting mirror 81 has already been adjusted upon completion of the X-direction adjustment step, it may be fixed after the X-direction adjustment step and before the Z-direction adjustment step.

[0092] As described above, the following effects can be obtained in this embodiment. For example, when the imaging position in the sub-scanning direction on the photosensitive drum 200 is deviated from the designed imaging position 210 as shown by the solid line in FIG. 17(a) of the comparative example, it is possible to adjust the imaging position to the designed imaging position 210 by moving the angle of the reflecting mirror 81 as shown in FIG. 17(b). However, when only the angle of the reflecting mirror 81 is adjusted, even if the imaging position is adjusted, the passing position of the beam B in the second scanning lens 70 may remain outside the set range. If the passing position of the beam B in the second scanning lens 70 remains outside the set range, it is considered that the imaging state on the scanned surface may deteriorate when the beam B is scanned in the main scanning direction. That is, in order to improve the imaging state on the scanned surface at all scanning positions, it is desirable that the passing position of the beam B in the scanning lens 70 does not deviate from the set range.

[0093] In contrast to this, in the present embodiment, in the manufacturing method of the scanning optical device 1, in order to adjust the incident position on the scanned surface in the sub-scanning direction, both the incident angle of the beam B from the light source to the mirror surface of the polygon mirror 51 in the sub-scanning direction and the angle of the reflecting mirror 81 are adjusted, so that it is possible to prevent the passing position of the beam B on the second scanning lens 70, which is the scanning lens through which the beam B last passes, from going out of a set range. As a result, it is possible to prevent the imaging state on the scanned surface from deteriorating.

[0094] Furthermore, as shown in FIG. 13, by moving the coupling lens 20 in the sub-scanning direction in the X-direction adjustment process, the incident angle from the light source to the mirror surface of the polygon mirror 51 in the sub-scanning direction can be easily adjusted.

[0095] In the fixing step, the position of the coupling lens 20 in the sub-scanning direction is fixed relative to the frame F, whereby the incident angle of the beam B with respect to the mirror surface of the polygon mirror 51 in the sub-scanning direction is fixed.

[0096] By having a Y-direction adjustment process after the mounting process, as shown in FIG. 12, the X-direction adjustment process can be easily performed after determining the angle of incidence in the main scanning direction on the mirror surface of the polygon mirror 51.

[0097] By having a Z-direction adjustment process after the X-direction adjustment process, as shown in FIG. 14, even if the focal position moves due to the X-direction adjustment process, the focal position can be easily aligned with the scanned surface by making adjustments in the subsequent processes.

[0098] 13, in the X-direction adjustment process, the second sensor 140 is placed between the reflecting mirror 81 and the scanned surface, not on the scanned surface, i.e., the second sensor 140 is placed at a position closer to the second scanning lens 70 than the scanned surface. Therefore, the angle at which the beam B advances can be adjusted based on the detection result of the first sensor 130 and the detection result of the second sensor 140 placed at a different position from the first sensor 130. Therefore, the first sensor 130 and the second sensor 140 can detect not only the imaging position but also the passing position of the beam B. As a result, it is possible to prevent the passing position of the beam B in the second scanning lens 70, which is the scanning lens through which the beam B passes last, from being out of the set range.

[0099] In addition, in the X-direction adjustment process, by disposing the second sensor 140 between the second scanning lens 70 and the surface to be scanned, the position of the beam B can be detected even if the distance between the reflecting mirror 81 and the second scanning lens 70 is narrow.

[0100] Furthermore, in the X-direction adjustment process, by arranging the first sensors 130 at two locations, it is possible to accurately detect the inclination of the scanning line on the surface to be scanned with respect to the main scanning direction.

[0101] In addition, the second sensor 140 is disposed at a position closer to the second scanning lens 70 than the intermediate position between the second scanning lens 70 and the surface to be scanned. The closer the detection surface of the second sensor 140 is to the second scanning lens 70, the easier it is to accurately detect the position in the sub-scanning direction where the beam B passes through the second scanning lens 70. This makes it possible to accurately detect the passing position in the sub-scanning direction at the second scanning lens 70 of the beam B traveling from the reflecting mirror 81 toward the surface to be scanned, compared to when the distance between the first sensor 130 and the second sensor 140 is short.

[0102] The present disclosure is not limited to the above-described embodiment, but can be used in various forms as exemplified below.

[0103] In the above-described embodiment, the coupling lens 20 is moved when adjusting the incident angle of the beam B from the semiconductor laser 10 and the coupling lens 20, which are the light source, but the orientation of the entire light source may be moved. For example, the incident angle of the beam B may be adjusted by changing the orientation of the entire light source by moving both the semiconductor laser 10 and the coupling lens 20.

[0104] In the embodiment described above, two first sensors 130 are disposed in the X-direction adjustment step, but one first sensor 130 or three or more first sensors 130 may be disposed.

[0105] In the above-described embodiment, the coupling lens and the like are fixed to the seating surface using a photocurable resin, but the present invention is not limited to this, and for example, the coupling lens and the like may be fixed to the seating surface using an adhesive other than a photocurable resin. Also, the coupling lens and the like may be fixed to the seating surface by a fixing method other than the adhesive, such as welding.

[0106] In the above-described embodiment, the reflecting mirror 81 was supported on the seating surface FsZ so as to be tiltable around an axis extending in the sub-scanning direction, but it may also be configured so as to be fixed by a photocurable resin or the like without being supported by the seating surface.

[0107] In the above-described embodiment, the coupling lens 20, the reflecting mirror 81, etc. are adjusted by an operator in each of the work steps of the X-direction adjustment step, the Y-direction adjustment step, and the Z-direction adjustment step, but all or some of the steps may be adjusted by an adjustment machine, an adjustment robot, etc.

[0108] The elements described in the above-mentioned embodiment and modified examples may be implemented in any combination. [Explanation of symbols]

[0109] 1. Scanning optical device 10 Semiconductor laser 20 Coupling Lens 50 Deflector 51 Polygon Mirror 60 First scanning lens 70 Second scanning lens 81 Reflective Mirror 130 First Sensor 140 Second Sensor 200 Photosensitive drum F Frame Li incidence optical system Lo scanning optics

Claims

1. a light source including a semiconductor laser and a coupling lens that converts light emitted from the semiconductor laser into a beam; a deflector having a polygon mirror and deflecting the beam emitted from the light source in a main scanning direction; a scanning optical system that forms an image of the beam deflected by the deflector on a scanned surface, the scanning optical system having a first scanning lens, a second scanning lens disposed downstream of the first scanning lens in a beam traveling direction, and a reflecting mirror disposed between the first scanning lens and the second scanning lens in the beam traveling direction; a frame to which the light source, the deflector, and the scanning optical system are attached, the method comprising the steps of: a mounting step of mounting the deflector, the first scan lens, and the second scan lens on the frame; an X-direction adjustment step of adjusting, after the mounting step, both an incident angle of the beam from the light source with respect to the mirror surface of the polygon mirror in the sub-scanning direction and an angle of the reflecting mirror to adjust a position of the beam in the sub-scanning direction on the scanned surface and a position of the beam in the sub-scanning direction on the second scanning lens; a fixing step of fixing an incident angle of a beam from the light source to a mirror surface of the polygon mirror in a sub-scanning direction and an angle of the reflecting mirror after the X-direction adjustment step.

2. 2. The method for manufacturing a scanning optical device according to claim 1, wherein in the X-direction adjustment step, when an incident angle in the sub-scanning direction of the beam from the light source with respect to the mirror surface of the polygon mirror is adjusted, the coupling lens is moved in the sub-scanning direction.

3. 3. The method for manufacturing a scanning optical device according to claim 2, wherein in the fixing step, the position of the coupling lens with respect to the frame is fixed.

4. 2. The method for manufacturing a scanning optical device according to claim 1, further comprising, after the mounting step and before the X-direction adjustment step, a Y-direction adjustment step of adjusting an incident angle in the main scanning direction to the deflector by moving the coupling lens in the main scanning direction.

5. 2. The method for manufacturing a scanning optical device according to claim 1, further comprising, after the X-direction adjustment step, a Z-direction adjustment step of adjusting a focal position by moving the coupling lens in the beam traveling direction.

6. In the X-direction adjustment step, a first sensor for detecting a position of the beam in a sub-scanning direction is disposed at a position corresponding to the surface to be scanned; a second sensor for detecting a position of the beam in the sub-scanning direction is disposed between the reflecting mirror and the surface to be scanned; 2. The method for manufacturing a scanning optical device according to claim 1, wherein adjustment is made based on detection results of the first sensor and the second sensor.

7. 5. The method for manufacturing a scanning optical device according to claim 4, wherein the second sensor is disposed between the second scanning lens and the surface to be scanned.

8. The second sensor is disposed at a center portion in a main scanning direction, 7. The method for manufacturing a scanning optical device according to claim 6, wherein the first sensors are disposed at at least two positions sandwiching the second sensor in the main scanning direction.

Images