Optical device

Abstract

To provide an optical device that can align a light source and a collimator lens easily and has high optical characteristics.SOLUTION: An optical device has a light source package, a light source holder, a lens holder, and a base member. In the light source package, a light source is mounted on a mounting surface in a direction for emitting light in a first direction along a mounting surface of a board. The light source holder has a flat mounting surface in face-contact with the back of the board that is parallel with the mounting surface, and a flat reference surface orthogonal to the mounting surface, and holds the light source package in a direction in which the reference surface is orthogonal to the first direction. The lens holder holds a collimator lens that transmits light emitted from the light source and allows it to be parallel light. The base member has a flat abutting surface in face-contact with the reference surface of the light source holder, and aligns and fixes the light source holder and the lens holder such that the focus of the collimator lens is matched to the light emitting surface of the light source and the light axis of light emitted from the light source is matched to the light axis of the collimator lens.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] An embodiment of the present invention relates to an optical device incorporated in, for example, an optical scanning device of an image forming apparatus. [Background technology]

[0002] For example, an optical scanning device of an image forming apparatus includes an optical device that integrates a semiconductor laser and a pre-deflection optical system including a collimator lens into a single unit. To form an electrostatic latent image on the surface of a photosensitive drum without misalignment or distortion using the optical scanning device, it is necessary to align the optical axis of the semiconductor laser with the optical axis of the collimator lens and to precisely align the focus of the collimator lens with the light-emitting surface of the semiconductor laser.

[0003] For example, the semiconductor laser is fixed by press-fitting into a hole in the base, and the collimator lens is fixed with an adhesive to a lens barrel attached to the base. At this time, for example, the light emitted from the semiconductor laser and transmitted through the collimator lens is monitored, and the semiconductor laser and collimator lens are fixed in a position that does not cause misalignment or distortion in the image. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-82710 Summary of the Invention [Problem to be solved by the invention]

[0005] For example, to adjust the position of the semiconductor laser relative to the base, it is necessary to move the semiconductor laser relative to the hole in the base. Also, to adjust the position of the collimator lens relative to the lens barrel, it is necessary to move the collimator lens relative to the lens barrel before the adhesive hardens. Therefore, aligning the semiconductor laser and the collimator lens is time-consuming and difficult, making it difficult to align them with high precision, and it is difficult to obtain an optical device with sufficiently high optical characteristics.

[0006] The problem to be solved by the present invention is to provide an optical device that allows easy alignment of a light source and a collimator lens and has high optical characteristics. [Means for solving the problem]

[0007] An optical device according to an embodiment includes a light source package, a light source holder, a lens holder, and a base member. The light source package has a light source mounted on the mounting surface of the substrate so that the light source emits light in a first direction along the mounting surface. The light source holder has a flat mounting surface that contacts the back surface of the substrate, which is parallel to the mounting surface, and a flat reference surface that is perpendicular to the mounting surface, and holds the light source package so that the reference surface and the first direction are perpendicular to each other. The lens holder holds a collimator lens that transmits light emitted from the light source to collimate it. The base member has a flat abutment surface that contacts the reference surface of the light source holder, and aligns and fixes the light source holder and the lens holder so that the focal point of the collimator lens is aligned with the light-emitting surface of the light source and the optical axis of the light emitted from the light source is aligned with the optical axis of the collimator lens. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of an image forming apparatus incorporating an optical device according to an embodiment. [Figure 2] FIG. 2 is a plan view of the optical scanning device incorporated in the image forming apparatus of FIG. [Figure 3] FIG. 3 is a perspective view of an optical device according to an embodiment incorporated in the optical scanning device of FIG. [Figure 4] FIG. 4 is an exploded perspective view of the optical device of FIG. [Figure 5] FIG. 5 is a perspective view of a light source package of the optical device of FIG. [Figure 6] FIG. 6 is a perspective view of a light source unit in which the light source package of FIG. 5 is attached to a light source holder. [Figure 7] FIG. 7 is a perspective view of the light source unit of FIG. 6 as viewed from a different direction. [Figure 8] FIG. 8 is a perspective view of the optical device of FIG. 3, seen from a different direction. [Figure 9] FIG. 9 is a bottom view of the optical device of FIG. 3 as seen from the bottom side of the base member. [Figure 10] 10A to 10C are diagrams for explaining a procedure for adjusting the fixed position of the lens holder with respect to the base member of the optical device of FIG. [Figure 11] 11A to 11C are diagrams for explaining a procedure for adjusting the fixing position of the light source holder with respect to the base member of the optical device of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] An image forming apparatus 1 (MFP: Multi Function Peripheral) incorporating an optical device 100 according to one embodiment of the present invention will be described with reference to Fig. 1. The optical device 100 can be incorporated into image forming apparatuses such as printers and copiers, as well as distance measuring devices.

[0010] In the following description, the same components are denoted by the same reference numerals, and redundant description may be omitted. Note that the scale of each part in the drawings used in the following description may be changed as appropriate. Also, the drawings may show simplified or omitted configurations to make the description easier to understand.

[0011] The image forming apparatus 1 of this embodiment includes an image reading unit 10 and an image forming unit 20. The image reading unit 10 includes an automatic document feeder 11. The automatic document feeder 11 feeds a stack of multiple documents one by one onto a document table. The image reading unit 10 reads image information from the document fed to the document table by the automatic document feeder 11 or from a document placed on the document table by a user, and converts the information into image data.

[0012] The image forming unit 20 forms an image on paper based on image data read from a document by the image reading unit 10 or image data transmitted from an external device such as a personal computer. The image forming unit 20 includes a paper feed cassette 21, an optical scanning device 30, a photosensitive drum 22, a developing unit 25, a fixing unit 23, and a paper output tray 24.

[0013] The paper feed cassette 21 stores a plurality of stacked sheets of paper. The image forming unit 20 picks up the sheets one by one from the paper feed cassette 21 using a pickup roller, and transports the sheets to the photosensitive drum 22 using a plurality of transport rollers.

[0014] The surface 221 of the photosensitive drum 22 is the scanned surface that is exposed and scanned by the optical scanning device 30. The direction parallel to the rotation axis of the photosensitive drum 22 within the scanned surface (the direction perpendicular to the paper surface in FIG. 1) is the main scanning direction, and the direction perpendicular to the main scanning direction within the scanned surface (the direction in which the surface 221 of the photosensitive drum 22 rotates) is the sub-scanning direction. For ease of explanation, hereinafter, all directions parallel to the rotation axis of the photosensitive drum 22, not limited to within the scanned surface, will be referred to as the main scanning direction, and all directions corresponding to the rotation direction of the surface 221 of the photosensitive drum 22 will be referred to as the sub-scanning direction.

[0015] The optical scanning device 30 emits light based on image data and scans the surface 221 of the photosensitive drum 22 in the main scanning direction. At this time, the optical scanning device 30 forms an electrostatic latent image based on the image data on the surface 221 as the photosensitive drum 22 rotates in the sub-scanning direction. The developing unit 25 develops the electrostatic latent image formed on the surface 221 of the photosensitive drum 22 by the optical scanning device 30 with a developer. The image forming unit 20 transfers the developer image formed on the surface 221 of the photosensitive drum 22 onto a sheet of paper transported from the paper feed cassette 21. The fixing unit 23 heats the developer image transferred to the sheet of paper to fix it to the sheet of paper. The image forming unit 20 discharges the sheet of paper that has passed through the fixing unit 23 and has the image formed thereon onto the paper output tray 24.

[0016] 2, the optical scanning device 30 has an optical device 100 in which a light source 31 and a collimator lens 32 are aligned with each other and fixed to a base member 101. The optical scanning device 30 also has an aperture plate 33, a cylindrical lens 34, a polygon mirror 35, a scanning lens 36, a mirror 37, and a housing 38 that houses these components 100, 30, 33, 34, 35, 36, and 37.

[0017] The collimator lens 32 transmits the divergent light emitted from the light source 31 and converts it into parallel light. The diaphragm plate 33 has an opening that passes the light that has passed through the collimator lens 32. The cylindrical lens 34 converges the light that has passed through the opening of the diaphragm plate 33 in the sub-scanning direction.

[0018] The polygon mirror 35 is a rotary polygonal mirror having a plurality of reflective surfaces (six in this embodiment) on its outer circumferential surface. The polygon mirror 35 is rotatably attached to the housing 38 at an angle such that its rotation axis is parallel to the sub-scanning direction. As the polygon mirror 35 rotates, it reflects the light that has passed through the cylindrical lens 34 at the plurality of reflective surfaces, and deflects the light reflected by each reflective surface in the main scanning direction.

[0019] The scanning lens 36 extends in the main scanning direction and is fixed to the housing 38, and converges the light reflected by each reflective surface of the polygon mirror 35 in the sub-scanning direction. The mirror 37 extends in the main scanning direction and is fixed to the housing 38, and reflects the light that has passed through the scanning lens 36 toward the surface 221 of the photosensitive drum 22. A plurality of mirrors 37 may be used in combination.

[0020] The optical device 100 will be described below with reference to FIGS. In each figure, assuming that the optical device 100 is incorporated into the optical scanning device 30 of the image forming apparatus 1, the direction parallel to the optical axis L of the light emitted from the light source 31 (first direction) is indicated by arrow X, the horizontal direction perpendicular to the optical axis L (second direction) is indicated by arrow Y, and the vertical direction perpendicular to the optical axis L (third direction) is indicated by arrow Z. The direction indicated by arrow Y corresponds to the deflection direction of the light by the polygon mirror 35 (main scanning direction). The direction indicated by arrow Z corresponds to the rotation direction of the photosensitive drum 22 (sub-scanning direction).

[0021] 3 and 4, the optical device 100 includes a light source package 103 in which a light source 31 is mounted on a mounting surface 1021 of a substrate 102, a light source holder 104 that holds the light source package 103, a lens holder 105 that holds a collimator lens 32, and a base member 101 in which the light source holder 104 and the lens holder 105 are aligned and fixed to each other. The assembly in which the light source package 103 is held by the light source holder 104 is a light source unit 1000. The base member 101 fixes the light source holder 104 (light source unit 1000) that holds the light source package 103 and the lens holder 105 in an aligned state so that the optical axis L of the light emitted from the light source 31 and the optical axis of the collimator lens 32 coincide with each other and the focal point (back focus) of the collimator lens is located on the light emitting surface 311 of the light source 31.

[0022] As shown in Fig. 5, light source package 103 has light source 31 and connector 107 mounted on mounting surface 1021 of flat rectangular substrate 102 that is elongated in the X direction and has a uniform thickness. The light source 31 is mounted on mounting surface 1021 at a position offset toward one end of the substrate 102 in the longitudinal direction. The connector 107 is mounted on mounting surface 1021 at a position offset toward the other end of the substrate 102 in the longitudinal direction. The light source 31 and connector 107 are arranged side by side and spaced apart in the X direction. Although not shown, a drive circuit for causing light source 31 to emit light is mounted on substrate 102.

[0023] The light source 31 may be a multi-channel laser diode or the like in which a plurality of light-emitting elements are arranged in the main scanning direction (the short-side direction of the substrate 102). The light source 31 has a flat light-emitting surface 311 that emits light, and has an optical axis L that passes through the center of the light-emitting surface 311 and is perpendicular to the light-emitting surface 311. The light source 31 is fixed to the mounting surface 1021 of the substrate 102 so that the optical axis L is parallel to the mounting surface 1021 of the substrate 102 and parallel to the longitudinal direction of the substrate 102.

[0024] 3 and 4 to the substrate 102. The optical scanning device 30 provides a drive signal based on image data to the light source 31 via the FPC 106, the connector 107, and the wiring of the substrate 102.

[0025] As shown in FIGS. 6 and 7 , the light source holder 104 has a flat mounting surface 1041. The mounting surface 1041 is in surface contact with a flat back surface 1022, which is parallel to the mounting surface 1021 of the substrate 102 of the light source package 103. The mounting surface 1041 is slightly larger than the substrate 102 and is a substantially rectangular surface whose width in the X direction is greater than its width in the Y direction. The light source holder 104 integrally includes a mounting portion 1042 having a substantially rectangular plate shape and a fixing portion 1044 having a substantially rectangular plate shape. The fixing portion 1044 is continuous with one end of the mounting portion 1042 in the longitudinal direction (X direction). The mounting surface 1041, to which the light source package 103 is attached, is a surface parallel to the XY plane and is located on the surface of the mounting portion 1042. The fixing portion 1044 is disposed parallel to the YZ plane, which is perpendicular to the mounting surface 1041.

[0026] The fixed portion 1044 has four screw holes 10441 near its four corners, which penetrate the fixed portion 1044 in the X direction. Two of the four screw holes 10441 are located at positions overlapping the mounting portion 1042. Therefore, the end of the mounting portion 1042 on the fixed portion 1044 side has recesses 1049 for accommodating the tips of the screws 109 inserted into the two screw holes 10441 located at positions overlapping the mounting portion 1042.

[0027] The fixed portion 1044 has four annular protruding portions 10443 integrally formed on a fixed end surface 10442 opposite the mounting portion 1042, which coaxially surround one end of the four screw holes 10441. The four protruding portions 10443 have annular flat reference surfaces 10444 at their tips in the protruding direction. The four reference surfaces 10444 are in the same plane parallel to the YZ plane and function as flat reference surfaces perpendicular to the mounting surface 1041 of the mounting portion 1042.

[0028] The light source holder 104 has four screws 1045 and four washers 1046 for fastening and fixing the light source package 103 to the mounting surface 1041. The light source package 103 is attached to the light source holder 104 by adjusting the orientation of the light source package 103 using an external adjustment device (not shown) so that the light emitting surface 311 of the light source 31 is parallel to the reference surface 10444 of the light source holder 104.

[0029] The light source package 103 is fixed to the light source holder 104 with the back surface 1022 of the substrate 102 in surface contact with the mounting surface 1041 of the light source holder 104 and the light-emitting surface 311 adjusted to be parallel to the reference surface 10444 of the light source holder 104. At this time, screws 1045 are threaded through washers 1046 into screw holes (not shown) provided in the mounting surface 1041 at positions close to the outside of the four corners of the substrate 102. As a result, the four washers 1046 press the four corners of the substrate 102, fixing the light source package 103 to the mounting surface 1041 of the light source holder 104. In this state, the optical axis L of the light emitted from the light source 31 is perpendicular to the reference surface 10444 of the light source holder 104.

[0030] An FPC 106 is connected to the connector 107 of the light source package 103. The FPC 106 is wired through a substantially rectangular opening 1047 provided in the fixing portion 1044 of the light source holder 104. Because the connector 107 is attached to the substrate 102 of the light source package 103, there is no need to place components outside the fixing portion 1044 of the light source holder 104, which increases the degree of freedom in the mounting design of the light source holder 104. Furthermore, the opening 1047 through which the FPC 106 passes can be a rectangular hole with a narrow width in the Z direction, which increases the mechanical strength of the fixing portion 1044 compared to when a circular hole is provided for attaching a can package as in the past.

[0031] In addition, the light source holder 104 has a notched step portion 1048 for avoiding contact with a support portion 1054 of the lens holder 105, which will be described later, and the above-mentioned recess 1049 for accommodating the tip of the screw 109 for fastening and fixing the fixed portion 1044 of the light source holder 104 to the standing wall portion 1013 of the base member 101, which will be described later. The notched step portion 1048 is formed by cutting out a part of the light source holder 104 so that the light source holder 104, whose fixed end is fixed in a cantilevered state by the standing wall portion 1013 of the base member 101, which will be described later, is positioned in a non-contact state with respect to the lens holder 105.

[0032] Furthermore, the light source holder 104 has four flat abutment surfaces 10431, 10432, 10433, and 10434 against which jigs 112, 113, 114, and 115 (FIG. 11), which will be described later, abut. The jigs 112, 113, 114, and 115 ...4, and 115 abut. The jigs 112, 114, and 115 abut. The jigs 112, 114, and 115 abut. The jigs 112, 114, and 115 abut. The jigs 112, 114, and 115 abut against the fixed portion 1044. The jigs 112, 114, and 115 abut. The jigs 112, 114, and 115 abut against the fixed portion 1044. The jigs 112, 114, and 115 abut against the fixed portion 1044. The jigs 112, 114, and 115 abut against the fixed portion 1044. The

[0033] As shown in FIG. 4, the lens holder 105 integrally includes a holding portion 1051 that holds and fixes the collimator lens 32, and a support portion 1054 that has two slider protrusions 1052 and 1053. The holding portion 1051 is a portion that is arranged parallel to the YZ plane, and the support portion 1054 is a portion that is arranged parallel to the XY plane. The holding portion 1051 is a substantially rectangular plate that has a thickness in the optical axis direction of the collimator lens 32, and the substantially rectangular plate-like support portion 1054 is integrally connected to one end of the holding portion 1051 in the Z direction. The support portion 1054 extends in the optical axis direction of the collimator lens 32. In other words, the lens holder 105 has an L-shaped cross section.

[0034] The two slider protrusions 1052, 1053 are protrusions that protrude from a bottom surface 1055 of the support part 1054 on the side opposite to the holding part 1051. The two slider protrusions 1052, 1053 are aligned apart from each other in the optical axis direction of the collimator lens 32. The two slider protrusions 1052, 1053 protrude to the same height from the bottom surface 1055. A space 1056 between the two slider protrusions 1052, 1053 functions as a fitting recess into which the tip of a jig 111 (FIG. 10), which will be described later, is fitted.

[0035] The lens holder 105 also has two screw holes 1057 for threading in screws 108 that fasten the lens holder 105 to the base member 101. The two screw holes 1057 are provided on the bottom surface 1055 of the lens holder 105, side by side and spaced apart in the Y direction. The two screw holes 1057 are on both sides in the Y direction of a space 1056 that is between the slider protrusions 1052 and 1053.

[0036] 3, 4, 8, and 9, the base member 101 integrally includes a bottom plate portion 1011, a base portion 1012, an upright wall portion 1013, and a reinforcing wall portion 1014. The bottom plate portion 1011 and the base portion 1012 function as a bottom wall portion disposed parallel to the XY plane perpendicular to the upright wall portion 1013. The base member 101 can be formed by die casting, which is relatively less susceptible to deformation due to heat.

[0037] The bottom plate portion 1011 is a substantially rectangular plate with a uniform thickness, and has a flat bottom surface 1010 that comes into surface contact with the flat mounting surface 381 of the housing 38 of the optical scanning device 30. The bottom plate portion 1011 has insertion holes 10111 at its four corners for inserting screws 39 ( FIG. 2 ). The screws 39 are used to fasten and fix the optical device 100 to the housing 38. The four insertion holes 10111 are holes that penetrate the bottom plate portion 1011 in the thickness direction and are holes that are perpendicular to the bottom surface 1010.

[0038] The bottom plate portion 1011 has a protruding portion 10113 with a positioning hole 10112 at one end in the X direction. The protruding portion 10113 is located at the center in the Y direction of one end of the bottom plate portion 1011. The hole 10112 is a circular hole that penetrates the protruding portion 10113 in the Z direction. The bottom plate portion 1011 also has a bottomed elongated hole 10114 for positioning on the opposite side of the protruding portion 10113 with respect to the center of the bottom surface 1010 in the X direction. The elongated hole 10114 is a hole with an oval cross section that is provided in the bottom surface 1010. The elongated hole 10114 extends in the X direction.

[0039] The optical device 100 can be positioned in the X and Y directions relative to the housing 38 by fitting a cylindrical boss (not shown) protruding from the mounting surface 381 of the housing 38 into a hole 10112 provided in a protruding portion 10113 of the base member 101, fitting a protrusion (not shown) protruding from the mounting surface 381 into an elongated hole 10114 of the base member 101, and bringing the bottom surface 1010 of the base member 101 into surface contact with the mounting surface 381 of the housing 38. In other words, the optical device 100 can be positioned relative to the housing 38 by the boss and protrusion provided at predetermined positions on the mounting surface 381 of the housing 38.

[0040] The optical device 100 can be fixed in a predetermined position on the housing 38 by positioning it relative to the housing 38 as described above and then screwing and fastening the screws 39 inserted into the four insertion holes 10111 in the bottom plate portion 1011 of the base member 101 into screw holes (not shown) provided at predetermined positions on the mounting surface 381 of the housing 38.

[0041] The bottom plate portion 1011 has a jig insertion hole 10115 through which a jig 112 ( FIG. 11 ) for adjusting the position of the light source holder 104 is inserted. The jig insertion hole 10115 is provided adjacent to the oblong hole 10114 on the opposite side of the protruding portion 10113, penetrating the bottom plate portion 1011 in the Z direction. The jig insertion hole 10115 penetrates the base portion 1012 in the thickness direction and extends to the mounting surface 10122 of the base portion 1012. The jig insertion hole 10115 is located opposite to the abutment surface 10431 of the fixing portion 1044 of the light source holder 104. That is, the jig insertion hole 10115 is located at a position where the tip 1121 of the jig 112 inserted into the jig insertion hole 10115 from the bottom surface 1010 side of the bottom plate portion 1011 abuts against the abutment surface 10431 of the light source holder 104.

[0042] The bottom plate portion 1011 has a jig insertion hole 10116 through which a jig 111 ( FIG. 10 ) is inserted for adjusting the position of the lens holder 105 in the X direction relative to the housing 38. The jig insertion hole 10116 is an oval hole that is long in the X direction so that the lens holder 105 can be moved in the X direction by moving the jig 111 in the X direction. The jig insertion hole 10116 is provided between the elongated hole 10114 and the protruding portion 10113, penetrating the bottom plate portion 1011 in the Z direction. The jig insertion hole 10116 communicates with a slide groove 10121 (described later) of the base portion 1012. The width of the jig insertion hole 10116 in the Y direction is slightly narrower than the width of the slide groove 10121. The jig insertion hole 10116 is located opposite a space 1056 between two slider protrusions 1052 and 1053 protruding from a bottom surface 1055 of the lens holder 105. In other words, the jig insertion hole 10116 is located at a position where the tip of the jig 111 inserted into the jig insertion hole 10116 from the bottom surface 1010 side of the bottom plate portion 1011 fits into the space 1056 between the two slider protrusions 1052 and 1053 of the lens holder 105.

[0043] The bottom plate portion 1011 has two counterbore holes 10117 that receive the heads of the screws 108 for fastening and fixing the lens holder 105. Each of the two counterbore holes 10117 is an oval hole with a bottom that extends in the X direction, and the depth from the bottom surface 1010 is slightly larger than the axial thickness of the head of the screw 108. The width of the two counterbore holes 10117 in the Y direction is slightly larger than the diameter of the head of the screw 108. The two counterbore holes 10117 are located on both sides in the Y direction, with the jig insertion hole 10116 sandwiched between them.

[0044] The bottoms of the two counterbore holes 10117 are connected to oval insertion holes 10118 that are slightly smaller than the counterbore holes 10117 and through which the shanks of the screws 108 pass. The insertion holes 10118 are holes formed coaxially with the counterbore holes 10117. The end of the insertion holes 10118 opposite the counterbore holes 10117 extends to a mounting surface 10122 of the base part 1012, which will be described later. The open end of the insertion holes 10118 on the mounting surface 10122 is positioned so as to overlap with the screw holes 1057 of the lens holder 105.

[0045] The base portion 1012 is a generally rectangular plate having a uniform thickness greater than that of the bottom plate portion 1011, and is a portion that is integrally connected to the surface of the bottom plate portion 1011 opposite the bottom surface 1010. The base portion 1012 has the same length in the X direction as the bottom plate portion 1011, and both end surfaces in the X direction are disposed flush with both end surfaces in the X direction of the bottom plate portion 1011. The width in the Y direction of the base portion 1012 is shorter than that of the bottom plate portion 1011, and the base portion 1012 is disposed in the center of the bottom plate portion 1011 in the Y direction. The four insertion holes 10111 in the bottom plate portion 1011 are positioned on both sides of the base portion 1012 in the Y direction.

[0046] The base portion 1012 has a slide groove 10121 that extends in the X direction and is disposed at the center in the Y direction. The slide groove 10121 is an elongated hole that penetrates the base portion 1012 in the thickness direction and can slidably receive the two slider protrusions 1052, 1053 of the lens holder 105. The width of the slide groove 10121 in the Y direction is such that the slider protrusions 1052, 1053 can be precisely fitted into the slide groove 10121 and that the lens holder 105 can only move in the optical axis direction. One end of the slide groove 10121 is open at the end surface of the base portion 1012 on the protruding portion 10113 side.

[0047] When attaching the lens holder 105 to the base member 101, the two slider protrusions 1052, 1053 of the lens holder 105 are fitted into the slide grooves 10121 of the base member 101, and the bottom surface 1055 of the lens holder 105 is brought into surface contact with the attachment surface 10122 of the base member 101. Then, after adjusting the attachment position of the lens holder 105 in the optical axis direction, the lens holder 105 is fastened and fixed to the base member 101 with two screws 108. At this time, the screws 108 are inserted into insertion holes 10118 from the bottom surface 1010 side via two countersunk holes 10117 provided in the bottom surface 1010 of the base member 101, and screwed into two screw holes 1057 provided in the bottom surface 1055 of the lens holder 105. By tightening the two screws 108, the lens holder 105 is fastened and fixed to the base member 101. The head of the screw 108 that fastens the lens holder 105 to the base member 101 fits into the countersunk hole 10117 in the bottom surface 1010 of the base member 101, so the head of the screw 108 does not protrude from the bottom surface 1010 of the base member 101.

[0048] The standing wall portion 1013 has a flat abutment surface 10131 that brings into surface contact with the above-mentioned four annular reference surfaces 10444 of the light source holder 104. The abutment surface 10131 is a surface that is perpendicular to the mounting surface 10122 of the base portion 1012. The standing wall portion 1013 has a back surface 10132 that is parallel to the abutment surface 10131 on the opposite side to the abutment surface 10131. The back surface 10132 is flush with the end surface of the base portion 1012 and the end surface of the base portion 1012, opposite the protruding portion 10113 of the bottom plate portion 1011. The standing wall portion 1013 has a substantially rectangular hole 10135 in its center that passes through the standing wall portion 1013 and connects the abutment surface 10131 and the back surface 10132.

[0049] The standing wall portion 1013 has four counterbore holes 10133 near the four corners of its back surface 10132. The four counterbore holes 10133 are holes arranged coaxially with the four screw holes 10441 of the light source holder 104. The diameter of each counterbore hole 10133 is larger than the diameter of the head of the screw 109, and the depth of each counterbore hole 10133 from the back surface 10132 is slightly larger than the axial thickness of the head of the screw 109. An insertion hole 10134, through which the shank of the screw 109 is inserted, is continuous with the bottom of each counterbore hole 10133. The insertion hole 10134 is a hole arranged coaxially with the counterbore hole 10133 and has an inner diameter larger than the diameter of the shank of the screw 109. That is, the countersunk hole 10133 and the insertion hole 10134 provided in the upright wall portion 1013 have a play between them and the screw 109 .

[0050] When fastening and fixing the light source unit 1000 to the standing wall portion 1013, the FPC 106 extending from the light source unit 1000 is inserted into the hole 10135 of the standing wall portion 1013, and the reference surface 10444 of the light source holder 104 is brought into surface contact with the abutment surface 10131 of the standing wall portion 1013. At this time, the four screw holes 10441 of the light source holder 104 and the four insertion holes 10134 of the standing wall portion 1013 are arranged coaxially. Then, four screws 109 are inserted through four countersunk holes 10133 formed in the back surface 10132 of the standing wall portion 1013, and the tips of the shanks of the screws 109 that have passed through the insertion holes 10134 are screwed into the four screw holes 10441 of the light source holder 104.

[0051] Because the diameter of the countersunk hole 10133 in the standing wall portion 1013 is larger than the diameter of the head of the screw 109 and the diameter of the insertion hole 10134 in the standing wall portion 1013 is larger than the diameter of the shank of the screw 109, when the screw 109 is threaded into the screw hole 10441 of the light source holder 104, the light source holder 104 can move in a direction along the YZ plane relative to the standing wall portion 1013. After adjusting the position of the light source holder 104 along the YZ plane relative to the standing wall portion 1013, the four screws 109 can be tightened to fasten the light source holder 104 to the standing wall portion 1013 of the base member 101. The light source holder 104 is held in a cantilevered state by the base member 101 and is out of contact with surrounding members except for the reference surface 10444.

[0052] The reinforcing wall portion 1014 is a substantially triangular plate that connects one Y-direction edge of the base portion 1012 and one Y-direction edge of the standing wall portion 1013. The width of the reinforcing wall portion 1014 in the X direction is the same as that of the base portion 1012, and the width in the Y direction is the same as that of the standing wall portion 1013. The reinforcing wall portion 1014 is a wall that is disposed along the XZ plane that is perpendicular to both the base portion 1012 and the standing wall portion 1013.

[0053] The reinforcing wall portion 1014 has a jig insertion hole 10141 (first jig insertion hole) through which a jig 114 (first jig in FIG. 11) is inserted for adjusting the position of the light source unit 1000 in the Y direction relative to the base member 101. The jig insertion hole 10141 is a hole that penetrates the reinforcing wall portion 1014 in its thickness direction, and is provided in the center in the Z direction near the end of the reinforcing wall portion 1014 on the standing wall portion 1013 side.

[0054] The standing wall portion 1013 has an escape recess 10136 at its end on the base portion 1012 side, which is a slight extension of the jig insertion hole 10115 of the base portion 1012. The standing wall portion 1013 has an escape recess 10137 at its end on the reinforcing wall portion 1014 side, which is a slight extension of the jig insertion hole 10141 of the reinforcing wall portion 1014.

[0055] Hereinafter, a procedure for adjusting the fixed positions of the light source holder 104 and the lens holder 105 of the light source unit 1000 relative to the base member 101 will be described with reference to FIGS.

[0056] Before adjusting the light source holder 104 and the lens holder 105, the light source holder 104 and the lens holder 105 are temporarily fixed to the base member 101. First, the slider protrusions 1052 and 1053 of the lens holder 105 are fitted into the slide grooves 10121 of the base member 101, and the lens holder 105 is temporarily fixed to the base member 101 with two screws 108. Then, the notched step portion 1048 of the light source holder 104 is placed on the lens holder 105, and the four screw holes 10441 of the light source holder 104 are coaxially arranged with the four insertion holes 10134 of the base member 101, and the light source holder 104 is temporarily fixed to the base member 101 with four screws 109.

[0057] After the temporary fixation, the optical device 100 is set on the external adjustment device, and as shown in FIG. 10 , a jig 111 is inserted through a jig insertion hole 10116 in the bottom surface 1010 of the base member 101, and the tip of the jig 111 is fitted into the space 1056 between the slider protrusions 1052 and 1053 of the lens holder 105. Then, the light emitted from the light source 31 and transmitted through the collimator lens 32 is monitored, and the jig 111 is moved in the X direction to adjust the back focus BF from the light-emitting surface 311 of the light source 31 to the rear end of the collimator lens 32. The back focus BF is the distance at which the focal point of the collimator lens 32 is located on the light-emitting surface 311 of the light source 31. At this position, the light transmitted through the collimator lens 32 being monitored is parallel light. In this state, the screws 108 are tightened to fasten and fix the lens holder 105 to the base member 101.

[0058] 11, the jig 112 is inserted into the jig insertion hole 10115 of the base member 101, the tip 1121 is brought into abutment against the abutment surface 10431 of the light source holder 104, and the sliding surface 1131 of the jig 113 (second jig) is brought into surface contact with the abutment surface 10432 on the opposite side facing the abutment surface 10431 in the Z direction. Also, the jig 114 is inserted into the jig insertion hole 10141 of the reinforcing wall portion 1014, and the tip 1141 is brought into abutment against the abutment surface 10433 of the light source holder 104, and the sliding surface 1151 of the jig 115 (third jig) is brought into surface contact with the abutment surface 10434 on the opposite side facing the abutment surface 10433 in the Y direction. In this state, the movement of the light source holder 104 in the Y direction and the Z direction is restricted, and the light source holder 104 is temporarily fixed.

[0059] The jigs 112 and 113 are movable only in the Z direction, and the jigs 114 and 115 are movable only in the Y direction. The rod-shaped jigs 112 and 114 have spherically curved tips that come into point contact with the abutment surfaces 10431 and 10433 of the light source holder 104, respectively. The block-shaped jigs 113 and 115 have flat sliding surfaces 1131 and 1151 at their tips in the moving direction, respectively, that are perpendicular to the moving direction. By having one (112) of the two jigs 112 and 113 that move in the Z direction while sandwiching the fixed portion 1044 of the light source holder 104 in the Z direction come into point contact with the abutment surface 10431, it is possible to prevent problems such as stress being applied to the light source holder 104 in directions other than the Z direction. In addition, by clamping the fixed portion 1044 of the light source holder 104 in the Y direction and bringing one (114) of the two jigs 114, 115, which move in the Y direction, into point contact with the abutment surface 10433, it is possible to prevent problems such as stress being applied to the light source holder 104 in directions other than the Y direction.

[0060] With the light source holder 104 temporarily fixed by the four jigs 112 to 115, light emitted from the light source 31 and transmitted through the collimator lens 32 is monitored, and the light source holder 104 is moved in the Y and Z directions relative to the base member 101 so that the optical axis L of the light source 31 coincides with the optical axis of the collimator lens 32. When moving the light source holder 104 in the Z direction, the jigs 112 and 113 are moved the same amount in the same direction (Z direction). At this time, the abutment surface 10434 of the light source holder 104 comes into sliding contact with the sliding surface 1151 of the jig 115, guiding the movement of the light source holder 104 in the Z direction. When moving the light source holder 104 in the Y direction, the jigs 114 and 115 are moved the same amount in the same direction (Y direction). At this time, the abutment surface 10432 of the light source holder 104 comes into sliding contact with the sliding surface 1131 of the jig 113, guiding the movement of the light source holder 104 in the Y direction. Then, after the optical axis L of the light source 31 and the optical axis of the collimator lens 32 are aligned, the screws 109 are tightened to fasten and fix the light source holder 104 to the base member 101.

[0061] As described above, the optical device 100 in which the optical axes of the light source 31 and collimator lens 32 are aligned by adjusting the back focus BF is fastened and fixed to the mounting surface 381 of the housing 38 of the optical scanning device 30 by screws 39.

[0062] As described above, the optical device 100 of this embodiment includes the light source 31 mounted on the substrate 102, so that the size in the Z direction can be reduced and the optical axis L can be easily aligned with the optical axis of the collimator lens 32. Furthermore, since the light source holder 104 holding the light source package 103 is fixed in a cantilevered state to the base member 101, heat from the light source 31 is not easily transferred to the light source holder 104, resulting in excellent heat dissipation. Furthermore, the base member 101 includes a reinforcing wall portion 1014, which provides high mechanical strength and prevents distortion due to heat.

[0063] Furthermore, because the jig 114 that abuts against the abutment surface 10433 of the light source holder 104 that faces the reinforcing wall portion 1014 is rod-shaped, the jig insertion hole 10141 through which the jig 114 passes can be made small, thereby maintaining the mechanical strength of the reinforcing wall portion 1014. Similarly, the jig insertion hole 10115 provided in the base member 101 can also be made small enough to allow the rod-shaped jig 112 to pass through, thereby maintaining the mechanical strength of the base member 101.

[0064] Furthermore, the abutment surface 10434 of the fixed portion 1044 of the light source holder 104 can function as a guide surface to guide the movement of the light source holder 104 in the Z direction, and the abutment surface 10432 of the fixed portion 1044 can function as a guide surface to guide the movement of the light source holder 104 in the Y direction, making it possible to accurately adjust the position of the light source holder 104 along the YZ plane. Thus, according to this embodiment, it is possible to provide an optical device 100 having good optical characteristics.

[0065] Although the embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. The above-described embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. The above-described embodiments are included within the scope and spirit of the invention, as well as within the scope of the inventions and their equivalents as set forth in the claims.

[0066] Other embodiments will be described below. 6. In the optical device of claim 3, the base member has a bottom wall portion that has a slide groove extending in the first direction into which the slider protrusion of the lens holder slidably fits and is perpendicular to the upright wall portion, and a reinforcing wall portion that is connected to the upright wall portion and the bottom wall portion. 7. In the optical device of "6" above, the light source holder has a first side surface facing the reinforcing wall portion, and the reinforcing wall portion has a first jig insertion hole for inserting a first jig whose tip abuts against the first side surface to restrict movement of the light source holder in a second direction perpendicular to the first direction. 8. In the optical device of claim 5, the base member has a bottom wall portion having the slide groove penetrating in the thickness direction and perpendicular to the upright wall portion, and the slider protrusion has a fitting recess into which the tip of a second jig inserted through the slide groove fits. 9. In the above item "8," the bottom wall portion has an insertion hole that is long in the first direction and through which a screw for fastening and fixing the lens holder is inserted. 10. In the optical device of claim 4, the light source holder has a flat first guide surface arranged parallel to the first direction and a second direction perpendicular to the first direction, and a flat second guide surface perpendicular to the second direction, the first guide surface being in sliding contact with the sliding surface of a second jig to guide movement in the second direction, and the second guide surface being in sliding contact with the sliding surface of a third jig to guide movement in a third direction perpendicular to the first and second directions. [Explanation of symbols]

[0067] 1...image forming apparatus, 10...image reading unit, 20...image forming unit, 22...photosensitive drum, 30...optical scanning device, 32...collimator lens, 38...housing, 381...mounting surface, 100...optical device, 101...base member, 102...substrate, 103...light source package, 104...light source holder, 105...lens holder, 1000...light source unit, 1010...bottom surface, 101 1...bottom plate portion, 10111...insertion hole, 10112...hole, 10113...protruding portion, 10114...oblong hole, 10115, 10116...jig insertion hole, 10117...counterbore hole, 10118...insertion hole, 1012...base portion, 10121...slide groove, 10122...mounting surface, 1013...standing wall portion, 10131...contact surface, 10132...back surface, 10133...counterbore hole, 1 0134...insertion hole, 10135...hole, 10136, 10137...relief recess, 1014...reinforcing wall portion, 10141...jig insertion hole, 1021...mounting surface, 1022...back surface, 1041...mounting surface, 1042...mounting portion, 10431 to 10434...butting surface, 1044...fixing portion, 10441...screw hole, 10442...fixing end surface, 10443...protruding portion, 1044 4...reference surface, 1045...screw, 1046...washer, 1047...opening hole, 1048...notched step portion, 1049...recess, 1051...holding portion, 1052, 1053...slider protrusion, 1054...support portion, 1055...bottom surface, 1056...space, 1057...screw hole, 106...FPC, 108, 109...screw, 111 to 115...jig, 1131, 1151...sliding surface.

Claims

1. a light source package having a light source mounted on the mounting surface of the substrate in a direction in which light is emitted in a first direction along the mounting surface of the substrate; a light source holder having a flat mounting surface that is in surface contact with a rear surface of the substrate parallel to the mounting surface and a flat reference surface that is perpendicular to the mounting surface, and that holds the light source package in an orientation in which the reference surface and the first direction are perpendicular to each other; a lens holder that holds a collimator lens that transmits light emitted from the light source to convert it into parallel light; a base member that has a flat abutment surface that comes into surface contact with the reference surface of the light source holder, and that aligns and fixes the light source holder and the lens holder so that the focal point of the collimator lens is aligned with the light emitting surface of the light source and the optical axis of the light emitted from the light source is aligned with the optical axis of the collimator lens; An optical device having:

2. the base member fixes the light source holder in a cantilever state with the reference surface in surface contact with the abutment surface as a fixed end; 10. The optical device of claim 1.

3. the base member has a vertical wall portion having the abutment surface, and the light source holder is fixed by threading a screw inserted into an insertion hole penetrating the vertical wall portion in a thickness direction into a screw hole provided to penetrate the reference surface of the light source holder.

3. The optical device according to claim 2.

4. the insertion hole provided in the standing wall portion has a play between it and the screw so as to allow movement of the light source holder relative to the standing wall portion in a direction perpendicular to the first direction; 4. The optical device according to claim 3.

5. the base member has a slide groove extending in the first direction, the lens holder has a slider protrusion that is slidably fitted into the slide groove; 10. The optical device of claim 1.

Images