Optical devices

Abstract

To provide an optical device that enables an optical member to be positioned with high accuracy.SOLUTION: An optical device has a light-source unit, an optical member, and a holder formed of a single member. The light-source unit comprises a light source emitting light in a first direction, and has a first positioning face perpendicular to the first direction on a surface. The optical member is separately opposed to the light-source unit in the first direction, and has an incidence plane on which the light emitted from the light source is incident, an emitting plane from which the incident light is emitted through the incident plane, and a second positioning face perpendicular to the first direction and provided at a position overlapping the first positioning face in the first direction on the face. The holder has a third positioning face in face-contact with the first positioning face, and a fourth positioning face in face-contact with the second positioning face and provided at a position overlapping the third positioning face in the first direction. The light-source unit is held while the first positioning face of the light-source unit is in face-contact with the third positioning face, and the optical member is held while the second positioning face of the optical member is in face-contact with the fourth positioning face.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] An embodiment of the present invention relates to an optical device using a lens mirror array. [Background technology]

[0002] A lens mirror array is made of, for example, transparent resin and has a long structure in which multiple tiny optical elements are arranged in a straight line. Each optical element has an incident lens surface on which light from a light emitting unit enters, an exit lens surface from which the incident light exits, and a reflective surface that reflects the light incident from the incident lens surface toward the exit lens surface. Lens mirror arrays are used in, for example, printers and copiers installed in the workplace.

[0003] When incorporating a lens mirror array into an exposure device of a copier, for example, the lens mirror array is attached to a holder that holds a light-emitting unit. In this case, the lens mirror array is attached to the holder with the incident lens surface of each optical element facing the light-emitting unit. Because the lens mirror array has a length approximately the same as the axial length of the photosensitive drum, it is relatively easy to bend and flex. For this reason, the lens mirror array needs to be attached to the exposure device while fixed to the holder, which is a rigid body.

[0004] Furthermore, the lens mirror array requires highly accurate positioning of the focal length between the incident lens surface of each optical element and the light-emitting unit. To position the lens mirror array relative to the light-emitting unit, light from the light-emitting unit is actually emitted through the lens mirror array, and the image is detected by a camera or the like, and the fixed position of the lens mirror array relative to the holder is fine-tuned. However, because the lens mirror array is soft and bends easily, it is difficult to accurately position the incident lens surface of each optical element relative to the light-emitting unit and attach it to the holder. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-32482 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide an optical device capable of positioning an optical member with high precision. [Means for solving the problem]

[0007] An optical device according to an embodiment includes a light source unit, an optical member, and a holder formed from a single member. The light source unit includes a light source that emits light in a first direction and has a first positioning surface on its surface that is perpendicular to the first direction. The optical member is disposed opposite the light source unit and spaced apart in the first direction. The optical member has an incident surface into which light emitted from the light source is incident, an exit surface from which light incident via the incident surface exits, and a second positioning surface on its surface that is perpendicular to the first direction and overlaps with the first positioning surface in the first direction. The holder has a third positioning surface that is in surface contact with the first positioning surface and a fourth positioning surface that is in surface contact with the second positioning surface and overlaps with the third positioning surface in the first direction. The holder holds the light source unit with the first positioning surface of the light source unit in surface contact with the third positioning surface, and holds the optical member with the second positioning surface of the optical member in surface contact with the fourth positioning surface. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing an image forming apparatus. [Figure 2] FIG. 2 is a schematic diagram showing the black unit of the image forming apparatus of FIG. [Figure 3] FIG. 3 is a schematic diagram showing the solid state head of the black unit of FIG. [Figure 4] FIG. 4 is a perspective view showing a lens mirror array incorporated in the solid head of FIG. [Figure 5]FIG. 5 is a perspective view of the lens mirror array of FIG. 4 as viewed from another direction. [Figure 6] FIG. 6 is a cross-sectional view of the lens mirror array of FIG. [Figure 7] FIG. 7 is a schematic diagram showing another fixing structure of the lens mirror array of FIG. [Figure 8] FIG. 8 is a schematic diagram showing another fixing structure of the light source unit. [Figure 9] FIG. 9 is a schematic diagram showing a modification of the solid state head of FIG. [Figure 10] FIG. 10 is a schematic diagram showing a document reading device of the image forming apparatus of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments will be described with reference to the drawings. Note that the scale of each part in the drawings used in the following description may be changed as appropriate. Also, in order to make the description easier to understand, the drawings may show simplified or omitted configurations.

[0010] The image forming apparatus 100 shown in FIG. 1 is a so-called multifunction peripheral having, for example, a printing function, a copying function, a scanning function, and the like. The image forming apparatus 100 has a housing 2. On the top surface of the housing 2 is a transparent platen glass 3 on which a document is placed. On the top surface of the housing 2 is a reading glass 5 which is arranged flush with the platen glass 3. The platen glass 3 and the reading glass 5 are aligned in the left-right direction (sub-scanning direction) in the figure.

[0011] An automatic document feeder (ADF) 4 is placed above the platen glass 3. The ADF 4 can open and close the platen glass 3. The ADF 4 functions as a platen press that holds down a document placed on the platen glass 3. The ADF 4 has the function of feeding a document through a reading glass 5.

[0012] The document reading device 10 is located within the housing 2 below the document table glass 3. The document reading device 10 is an example of an optical device as defined in the claims of the present application. The document reading device 10 includes a lens mirror array 20 (described later) that extends in a direction perpendicular to the plane of the paper (the main scanning direction). The document reading device 10 is movable in the sub-scanning direction along the document table glass 3 by a drive mechanism (not shown), and can be fixed below the reading glass 5 (at the position shown in FIG. 1). The document reading device 10 forms an erect image of the document on an image sensor 101 (FIG. 10) (described later).

[0013] When reading an original, for example, the original reading device 10 is fixed below the reading glass 5 (as shown in FIG. 1), the original is fed by the ADF 4, and illumination light is irradiated onto the original through the reading glass 5. The lens mirror array 20 guides the light reflected from the original and forms an image on the image sensor 101. The original reading device 10 photoelectrically converts the light reflected from the original received by the image sensor 101 and outputs it as an image signal.

[0014] At this time, the document reading device 10 reads the erect image of the document passing over the reading glass 5 line by line in the main scanning direction by the operation of the ADF 4. Then, as the document passes over the reading glass 5 in the sub-scanning direction, an image of the entire document (multiple lines) can be obtained.

[0015] Alternatively, when an original is set on the platen glass 3 and the original reading device 10 is moved in the sub-scanning direction along the platen glass 3, the erect image of the original formed on the image sensor 101 via the lens mirror array 20 can be read line by line along the main scanning direction to obtain the entire image of the original.

[0016] The image forming apparatus 100 has an image forming unit 30 located approximately in the center of the housing 2. The image forming unit 30 has a yellow unit 301, a magenta unit 302, a cyan unit 303, and a black unit 304, arranged along the running direction of the intermediate transfer belt 40. Since the color units 301, 302, 303, and 304 of the image forming unit 30 have approximately the same structure, the black unit 304 will be described here as a representative, and detailed descriptions of the other color units 301, 302, and 303 will be omitted.

[0017] As shown in FIG. 2, the black unit 304 includes, for example, a photosensitive drum 314, a main charger 324, a solid-state head 504, a developer 334, a primary transfer roller 344, a cleaner 354, and a blade 364. The solid-state head 504 is an example of an optical device described in the claims of the present application. The solid-state head 504 includes the lens mirror array 20 described above. The intermediate transfer belt 40 is wound around multiple rollers and stretched endlessly, and travels counterclockwise in FIG. 2.

[0018] The photosensitive drum 314 has a rotation axis extending in the main scanning direction. The photosensitive drum 314 rotates with its outer circumferential surface in contact with the surface of the intermediate transfer belt 40. A primary transfer roller 344 is located inside the intermediate transfer belt 40 and facing the photosensitive drum 314. The photosensitive drum 314 rotates in the direction of the arrow (clockwise) at the same peripheral speed as the intermediate transfer belt 40 by a drive mechanism (not shown).

[0019] The electrostatic charger 324 uniformly charges the surface of the photosensitive drum 314. The solid-state head 504 irradiates the surface of the photosensitive drum 314 with exposure light based on a color-separated black image signal, and forms an electrostatic latent image based on the black image signal on the surface of the photosensitive drum 314. The developing device 334 supplies black toner to the electrostatic latent image formed on the surface of the photosensitive drum 314, and forms a black toner image on the surface of the photosensitive drum 314.

[0020] The primary transfer roller 344 transfers the black toner image formed on the surface of the photosensitive drum 314 onto the toner images of other colors, superimposed on the black toner image, onto the intermediate transfer belt 40. The cleaner 354 and the blade 364 remove any toner remaining on the surface of the photosensitive drum 314. The toner images of each color superimposed and transferred onto the surface of the intermediate transfer belt 40 move as the intermediate transfer belt 40 moves.

[0021] Downstream of the black unit 304 along the running direction of the intermediate transfer belt 40, there is a pair of transfer rollers 37 for transferring the toner images of each color transferred in layers onto the surface of the intermediate transfer belt 40 onto the paper P. One of the transfer rollers, 371, is located inside the intermediate transfer belt 40 and wraps around the intermediate transfer belt 40. The other transfer roller, 372, faces the one transfer roller 371 with the intermediate transfer belt 40 sandwiched therebetween.

[0022] Returning to FIG. 1, near the bottom end of the housing 2 of the image forming apparatus 100 is a paper feed cassette 61 that stores a plurality of stacked sheets of paper P of a predetermined size. The paper feed cassette 61 can be pulled out and stored, for example, from the front of the housing 2. Above the right end of the paper feed cassette 61 in the drawing is a pickup roller 62 that picks up the topmost sheet P in the stacking direction of the sheets of paper P stored in the paper feed cassette 61. The pickup roller 62 rotates with its peripheral surface in contact with the sheets of paper P, thereby picking up the sheets of paper P one by one.

[0023] A paper output tray 63 is located at the top of the housing 2. The paper output tray 63 is located between the platen glass 3 and the image forming unit 30, and outputs paper P on which an image has been formed into the body of the image forming device 100. A transport path 64 is located between the pickup roller 62 and the paper output tray 63, for transporting paper P taken out of the paper feed cassette 61 in the vertical direction toward the paper output tray 63. The transport path 64 extends through the nip of the transfer roller pair 37, and is equipped with multiple transport roller pairs 641 and a transport guide (not shown). At the end of the transport path 64, there is a paper output roller pair 631 for discharging paper P to the paper output tray 63. The paper output roller pair 631 is rotatable in both forward and reverse directions.

[0024] A pair of fixing rollers 65 is located on the conveying path 64 downstream (above in the figure) of the pair of transfer rollers 37. The pair of fixing rollers 65 heats and presses the paper P conveyed through the conveying path 64, and fixes the toner image transferred onto the surface of the paper P to the surface of the paper P.

[0025] The image forming apparatus 100 has a reverse conveying path 66 for inverting the paper P with an image formed on one side and feeding it into the nip of the transfer roller pair 37. The reverse conveying path 66 has a plurality of conveying roller pairs 661 that convey the paper P by pinching and rotating it, and a conveying guide (not shown). Upstream of the paper discharge roller pair 631, there is a gate 67 that switches the conveying destination of the paper P between the conveying path 64 and the reverse conveying path 66.

[0026] When forming an image on paper P, image forming apparatus 100 rotates pickup roller 62 to pick up paper P from paper feed cassette 61, and transports paper P toward paper output tray 63 via transport path 64 using multiple transport roller pairs 641. At this time, image forming apparatus 100 sends the toner images of each color transferred and formed on the surface of intermediate transfer belt 40 to the nip of transfer roller pair 37 in accordance with the transport timing of paper P, and transfers the toner images of each color onto the surface of paper P by applying a transfer voltage using transfer roller pair 37.

[0027] The image forming apparatus 100 heats and presses the paper P, onto which the toner image has been transferred, by transporting the paper P through the fixing roller pair 65, thereby melting the toner image and pressing it against the surface of the paper P, thereby fixing the toner image to the paper P. Then, the image forming apparatus 100 discharges the paper P, onto which the image has been formed in this way, via the paper discharge roller pair 631 to the paper discharge tray 63.

[0028] At this time, if a double-sided mode in which an image is also formed on the back side of the sheet P is selected, the image forming apparatus 100 switches the gate 67 to the reverse conveyance path 66 just before the trailing edge of the sheet P in the discharge direction while being discharged to the sheet discharge tray 63 passes through the nip of the pair of sheet discharge rollers 631, and reverses the pair of sheet discharge rollers 631 to switchback convey the sheet P. As a result, the image forming apparatus 100 directs the trailing edge of the sheet P to the reverse conveyance path 66, turns the sheet P upside down, and sends it to the nip of the pair of transfer rollers 37.

[0029] Then, the image forming apparatus 100 forms a toner image based on the image data to be formed on the back side of the paper P on the front side of the intermediate transfer belt 40, and runs the intermediate transfer belt 40 carrying the toner images of each color, sending the toner images of each color into the nip of the transfer roller pair 37. Furthermore, the image forming apparatus 100 transfers and fixes the toner images on the back side of the inverted paper P, and discharges the paper P to the paper discharge tray 63 via the paper discharge roller pair 631.

[0030] The image forming apparatus 100 has a control unit 70 that controls the operation of each of the mechanisms described above. The control unit 70 includes a processor such as a CPU, and a memory. The control unit 70 realizes various processing functions by the processor executing programs stored in the memory. The control unit 70 controls the document reading device 10 to acquire image information from a document. The control unit 70 also controls the image forming unit 30 to form an image on the surface of the paper P. For example, the control unit 70 inputs the image information read by the document reading device 10 to the image forming unit 30. The control unit 70 controls the operation of multiple conveying roller pairs 641, 661 to convey the paper P through the conveying path 64 and the reverse conveying path 66.

[0031] 3 to 6, the solid head 504 of the black unit 304 will be described below. The solid heads 501, 502, and 503 of the other color units 301, 302, and 303 have the same structure as the solid head 504, and therefore detailed description thereof will be omitted.

[0032] As shown in FIG. 3 , the solid-state head 504 faces the photosensitive drum 314 below at a distance. The solid-state head 504 has a lens mirror array 20, a light source unit 52, and a holder 54. The holder 54 fixes the lens mirror array 20 and the light source unit 52 while positioning them with high precision in the optical axis direction. The lens mirror array 20 is an example of an optical member described in the claims of this application. These components 20, 52, and 54 of the solid-state head 504 extend in the main scanning direction perpendicular to the plane of the drawing and parallel to the rotation axis of the photosensitive drum 314, and have approximately the same length as the photosensitive drum 314.

[0033] As shown in Figures 4 and 5, the lens mirror array 20 has a structure in which a plurality of transparent optical elements 21 of the same shape are aligned in the main scanning direction and connected together. Figure 6 shows a cross section of the lens mirror array 20 taken along a plane perpendicular to the main scanning direction between two adjacent optical elements 21. The surfaces of the plurality of optical elements 21 are continuous surfaces that are connected in the main scanning direction over the entire length of the lens mirror array 20. In this embodiment, the lens mirror array 20 is formed by injection molding of a transparent resin. The lens mirror array 20 may also be formed from transparent glass.

[0034] Each optical element 21 of the lens mirror array 20 guides diffused light from an object point to form an image at an image point. One optical element 21 forms an image on the image plane from light from multiple object points aligned in the main scanning direction. For example, one optical element 21 forms an image on the image plane from light from object points arranged within a width two to three times the pitch of the optical elements 21 in the main scanning direction.

[0035] In the solid-state head 504, the object points of the multiple optical elements 21 of the lens mirror array 20 are set to the light emitting surfaces 5211 of the light emitting elements 521 of the light source unit 52, and the image point is set to the surface 3141 of the photosensitive drum 314. The lens mirror array 20 of the solid-state head 504 has multiple optical elements 21 arranged in the main scanning direction, and therefore guides light emitted from the multiple light emitting elements 521 arranged in the main scanning direction to form an elongated image on the surface 3141 of the photosensitive drum 314 along the main scanning direction.

[0036] Optical element 21 has, on its surfaces, an incident-side lens surface 22, an upstream-side reflecting surface 23, a downstream-side reflecting surface 24, and an exit-side lens surface 25. Incident-side lens surface 22, downstream-side reflecting surface 24, and exit-side lens surface 25 are curved surfaces that are convex outward. Upstream-side reflecting surface 23 is a flat surface. Optical element 21 reflects light incident on incident-side lens surface 22 at two reflecting surfaces 23, 24 and emits the light via exit-side lens surface 25. Because optical element 21 has two reflecting surfaces 23, 24, it forms an erect image of an object point at the image formation point.

[0037] The incident-side lens surfaces 22 of the optical elements 21 are an example of the incident surfaces described in the claims of the present application, and the exit-side lens surfaces 25 of the optical elements 21 are an example of the exit surfaces described in the claims of the present application. The upstream-side reflecting surface 23 and the downstream-side reflecting surface 24 are an example of the reflecting surfaces described in the claims of the present application.

[0038] Incident-side lens surface 22 of optical element 21 has a shape whose central axis coincides with the optical axis of light emitted from light-emitting element 521. Upstream-side reflective surface 23 is located on the optical path of light passing through incident-side lens surface 22 and is inclined at approximately 45° in the sub-scanning direction with respect to the central axis of incident-side lens surface 22. Downstream-side reflective surface 24 is located approximately parallel to upstream-side reflective surface 23 and shifted in the sub-scanning direction from upstream-side reflective surface 23. Exit-side lens surface 25 has a central axis that extends parallel to the central axis of incident-side lens surface 22 and shifted in the sub-scanning direction from the central axis of incident-side lens surface 22. In other words, the optical axis of the incident light incident on incident-side lens surface 22 of optical element 21 and the optical axis of the exiting light exiting from exit-side lens surface 25 are parallel to but spaced apart in the sub-scanning direction.

[0039] The light incident on incident-side lens surface 22 of optical element 21 is divergent light. Incident-side lens surface 22 converges the divergent light and directs it toward upstream-side reflective surface 23. The light reflected by upstream-side reflective surface 23 and downstream-side reflective surface 24 converges and then becomes divergent light, which is emitted via exit-side lens surface 25. Exit-side lens surface 25 converges and emits the light reflected by downstream-side reflective surface 24. Light that passes through the center of optical element 21 in the main scanning direction and travels through a cross section perpendicular to the main scanning direction is shown by a dashed line in Figure 6.

[0040] The lens mirror array 20 of the solid-state head 504 needs to focus the light emitted from the light-emitting elements 521 onto the surface of the photosensitive drum 314 without misalignment or distortion, so that the electrostatic latent image formed on the surface of the photosensitive drum 314 does not become misaligned or distorted. In other words, to form high-quality images in the image forming apparatus 100 of this embodiment, a lens mirror array 20 with extremely high dimensional accuracy and no misalignment or distortion is required. Furthermore, because the lens mirror array 20 is soft and easily bends, the holder 54 that holds the lens mirror array 20 needs to have high rigidity so as to prevent the lens mirror array 20 from bending or flexing.

[0041] Furthermore, in order to form a high-quality image using the solid-state head 504, it is necessary to assemble the solid-state head 504 after positioning the lens mirror array 20 and the light source unit 52 relative to each other with high precision. The holder 54 fixes the light source unit 52 and the lens mirror array 20 in a state in which they are positioned with high precision in the optical axis direction so that the object point of each optical element 21 of the lens mirror array 20 is positioned on the light-emitting surface 5211 of each light-emitting element 521 of the light source unit 52. Naturally, the solid-state head 504 also needs to be attached after being positioned with high precision relative to the surface 3141 of the photosensitive drum 314.

[0042] As shown in FIG. 3, the light source unit 52 has a substrate 522 on which a plurality of light-emitting elements 521 are mounted and arranged in the main scanning direction. The plurality of light-emitting elements 521 arranged in the main scanning direction may be arranged in a single row or in multiple rows arranged in the sub-scanning direction. The direction perpendicular to the mounting surface 5221 of the substrate 522 is parallel to the optical axis direction of the light emitted from the plurality of light-emitting elements 521 and is the first direction described in the claims of the present application. The light-emitting element 521 is an example of a light source described in the claims of the present application. The mounting surface 5221 of the substrate 522 of the light source unit 52 is an example of a first positioning surface described in the claims of the present application. In FIG. 3, the main scanning direction is indicated by arrow X, the sub-scanning direction is indicated by arrow Y, and the optical axis direction is indicated by arrow Z.

[0043] The lens mirror array 20 has an abutment surface 201 for positioning in the optical axis direction (Z direction) relative to the holder 54, located on the surface between the downstream-side reflecting surfaces 24 and the output-side lens surfaces 25 of the multiple optical elements 21. The abutment surface 201 is a flat surface that is parallel to a plane perpendicular to the optical axis direction (XY plane) when the lens mirror array 20 is incorporated into the solid-state head 504, and is an example of the second positioning surface described in the claims of the present application. When the lens mirror array 20 is incorporated into the solid-state head 504, the abutment surface 201 of the lens mirror array 20 is located so as to overlap in the optical axis direction with the mounting surface 5221 of the substrate 522 of the light source unit 52.

[0044] The lens mirror array 20 has an abutment surface 202, located on the surface between the downstream reflecting surfaces 24 of the multiple optical elements 21 and the abutment surface 201, for positioning the lens mirror array 20 in the sub-scanning direction (Y direction) relative to the holder 54. The lens mirror array 20 also has an abutment surface 203, located on the surface between the incident-side lens surfaces 22 of the multiple optical elements 21 and the downstream reflecting surfaces 24, for positioning the lens mirror array 20 in the sub-scanning direction (Y direction) relative to the holder 54. The two abutment surfaces 202, 203 are positioned apart in the optical axis direction. The two abutment surfaces 202, 203 are flat surfaces that are perpendicular to the optical axis direction and parallel to a plane (XZ plane) perpendicular to the main scanning direction (X direction) when the lens mirror array 20 is incorporated into the solid-state head 504, and are an example of a fifth positioning surface recited in the claims of the present application.

[0045] The holder 54 can be made of a synthetic resin such as polycarbonate. To improve the dimensional accuracy of the holder 54, it is desirable to make the holder 54 from a material with as small a thermal expansion coefficient as possible. The holder 54 can be made of aluminum, for example. The holder 54 is integrally formed from a single member.

[0046] Holder 54 has a slit 541 at its upper end that extends in the main scanning direction, and houses and arranges lens mirror array 20 and light source unit 52 inside. Slit 541 passes light that has been emitted via output-side lens surface 25 of lens mirror array 20 and guides it to surface 3141 of photosensitive drum 314. Cover glass 5420 is located on the photosensitive drum 314 side of slit 541.

[0047] An inner surface 542 that defines the storage space within the holder 54 includes three abutment surfaces 5421, 5422, and 5423 for positioning the lens mirror array 20, and an abutment surface 5424 for positioning the light source unit 52. The abutment surfaces 5422 and 5423 are parallel to the XZ plane and are used to position the lens mirror array 20 in the sub-scanning direction. The abutment surface 5421 is parallel to the XY plane and is used to position the lens mirror array 20 in the optical axis direction. The abutment surface 5424 is parallel to the XY plane and is used to position the light source unit 52 in the optical axis direction.

[0048] The contact surface 5424 of the holder 54 is an example of a third positioning surface as defined in the claims of the present application, and the contact surface 5421 of the holder 54 is an example of a fourth positioning surface as defined in the claims of the present application, and these two contact surfaces 5424, 5421 are positioned so as to overlap in the optical axis direction. The contact surfaces 5422, 5423 of the holder 54 are an example of a sixth positioning surface as defined in the claims of the present application.

[0049] When attaching the lens mirror array 20 to the holder 54, the abutment surface 201 of the lens mirror array 20 is brought into surface contact with the abutment surface 5421 of the holder 54, the abutment surface 202 of the lens mirror array 20 is brought into surface contact with the abutment surface 5422 of the holder 54, and the abutment surface 203 of the lens mirror array 20 is brought into surface contact with the abutment surface 5423 of the holder 54, thereby positioning the lens mirror array 20 with respect to the holder 54. In this state, an adhesive is provided between the lens mirror array 20 and the inner surface 542 of the holder 54, and the lens mirror array 20 is fixed to the holder 54. The fixing points with the adhesive are multiple points spaced apart along the main scanning direction, and are positions that do not interfere with the entrance-side lens surface 22, upstream-side reflecting surface 23, downstream-side reflecting surface 24, and exit-side lens surface 25 of the lens mirror array 20.

[0050] Alternatively, the lens mirror array 20 may be fixed to the holder 54 using a leaf spring or the like (not shown) so that the abutment surface 201 of the lens mirror array 20 is pressed against the abutment surface 5421 of the holder 54, the abutment surface 202 of the lens mirror array 20 is pressed against the abutment surface 5422 of the holder 54, and the abutment surface 203 of the lens mirror array 20 is pressed against the abutment surface 5423 of the holder 54. In this case, no adhesive need be used.

[0051] When attaching the light source unit 52 to the holder 54, the mounting surface 5221 of the substrate 522 is brought into surface contact with the abutment surface 5424 of the holder 54, and the light source unit 52 is positioned relative to the holder 54. In this state, the holder 54 is fixed to the support member 55 to which the surface opposite to the mounting surface 5221 of the light source unit 52 is fixed.

[0052] As described above, according to this embodiment, the holder 54 formed from a single member has the abutment surface 5424 for positioning the light source unit 52 in the optical axis direction, and also has the abutment surface 5421 for positioning the lens mirror array 20 in the optical axis direction at a position overlapping the abutment surface 5424 in the optical axis direction. Therefore, by fixing the light source unit 52 to the holder 54 by bringing the mounting surface 5221 of the light source unit 52 into surface contact with the abutment surface 5424 of the holder 54, and by fixing the lens mirror array 20 to the holder 54 by bringing the abutment surface 201 of the lens mirror array 20 into surface contact with the abutment surface 5421 of the holder 54, the lens mirror array 20 can be positioned and arranged with high precision in the optical axis direction with respect to the light source unit 52.

[0053] Therefore, according to this embodiment, in order to position the lens mirror array 20 in the optical axis direction relative to the light source unit 52, as in the conventional case, the light emitting element 521 is made to emit light while either the light source unit 52 or the lens mirror array 20 is temporarily fixed to the holder 54, the image formed on the image plane via the lens mirror array 20 is detected by a camera or the like, and adjustment work such as aligning the light source unit 52 or the lens mirror array 20 to a position where no misalignment occurs is no longer necessary, and stable optical performance can be obtained while simplifying the assembly process.

[0054] Furthermore, as in this embodiment, by arranging the portion where the mounting surface 5221 of the light source unit 52 contacts the abutment surface 5424 of the holder 54 and the portion where the abutment surface 201 of the lens mirror array 20 contacts the abutment surface 5421 of the holder 54 so that they overlap in the optical axis direction, it is possible to further improve the positioning accuracy of the light source unit 52 and the lens mirror array 20 in the optical axis direction. If the portion where the light source unit 52 contacts the holder 54 and the portion where the lens mirror array 20 contacts the holder 54 do not overlap in the optical axis direction, dimensional changes in the sub-scanning direction due to thermal expansion of the holder 54, etc., will have an effect, reducing the positioning accuracy of the light source unit 52 and the lens mirror array 20. Therefore, as in this embodiment, it is effective to arrange the portion where the mounting surface 5221 of the light source unit 52 contacts the abutment surface 5424 of the holder 54 and the portion where the abutment surface 201 of the lens mirror array 20 contacts the abutment surface 5421 of the holder 54 so that they overlap in the optical axis direction.

[0055] In the above-described embodiment, the mounting surface 5221 of the light source unit 52 is brought into contact with the abutment surface 5424 of the holder 54, and the abutment surface 201 of the lens mirror array 20 is brought into contact with the abutment surface 5421 of the holder 54. However, these surfaces 5221, 5424, 201, 5421 may be any surfaces that are perpendicular to the optical axis direction, and may also be separate surfaces provided on the surface of each component.

[0056] For example, the shape of the holder 54 may be modified so that the abutment surface 201 of the lens mirror array 20 is spaced apart from the abutment surface 5421 of the holder 54, as shown in Figure 7, and instead the abutment surface 204 at the tip of the flange portion 210 of the lens mirror array 20 is brought into surface contact with the abutment surface 5425 of the holder 54.

[0057] In this case, the abutment surface 204, which is closer to the light source unit 52 in the optical axis direction than the incident side lens surface 22, can be brought into contact with the abutment surface 5425 of the holder 54, and even if the holder 54 thermally expands, the distance between the abutment surface 5425 and the abutment surface 5424 is shorter than in the above-mentioned embodiment (Figure 3), so the dimensional change in the optical axis direction can be kept small, and positional misalignment between the light source unit 52 and the lens mirror array 20 in the optical axis direction can be suppressed.

[0058] It should be noted that if the lens mirror array 20 is brought into contact with the holder 54 as shown in Figure 7, it may become difficult to apply adhesive to fix the lens mirror array 20 to the holder 54. In this case, however, the lens mirror array 20 may be biased by a leaf spring or the like to press the contact surface 204 of the lens mirror array 20 against the contact surface 5425 of the holder 54.

[0059] 8, when a light source unit 90 is fixed to the holder 54 instead of the light source unit 52, the surface 921 of the light-transmitting panel 92 can be brought into surface contact with the abutment surface 5424 of the holder 54, thereby positioning the light source unit 90 in the optical axis direction. The light source unit 90 has a structure in which a light-emitting element 521 is fixed to the light-transmitting panel 92 and the light-emitting element 521 is covered with a cover member 94.

[0060] Furthermore, in the above-described embodiment, the holder 54 that holds the light source unit 52 and the lens mirror array 20 is formed from a single member, but a holder 80 that combines two members may also be used, as shown in Fig. 9. The holder 80 has the same shape as the holder 54 in the above-described embodiment when the fixing member 81 and the support member 82 are combined as shown in the figure.

[0061] The fixing member 81 has an abutment surface 5424 that comes into surface contact with the mounting surface 5221 of the substrate 522 of the light source unit 52, and an abutment surface 5421 that comes into surface contact with the abutment surface 201 of the lens mirror array 20. The support member 82 has a recess 821 into which a part of the fixing member 81 fits. In this way, even when the holder 80 is formed by combining a plurality of members, by providing the two abutment surfaces 5424, 5421 on the surface of the fixing member 81, which is a single member, it is possible to highly accurately position the light source unit 52 and the lens mirror array 20 in the optical axis direction.

[0062] 10 is a schematic diagram of a document reading device 10. The document reading device 10 has a reading unit 104 having a substrate 102 on which an image sensor 101 is mounted, a lens mirror array 20, a pair of illumination units 110, and a housing 120 in which these components 104, 20, and 110 are positioned and fixed.

[0063] The image sensor 101 is, for example, a long CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor extending in the main scanning direction. The illumination unit 110 has a long light-emitting section 111 extending in the main scanning direction, and a long light guide 112 extending in the main scanning direction that guides illumination light emitted from the light-emitting section 111 to illuminate the document surface.

[0064] The lens mirror array 20 of the document reading device 10 is attached upside down compared to the lens mirror array 20 of the solid-state head 504. In the document reading device 10, the object point of the lens mirror array 20 is on the document surface, and the image formation point is on the light receiving surface of the image sensor 101. In other words, the lens mirror array 20 of the document reading device 10 guides light reflected by the document surface and forms an image on the light receiving surface of the image sensor 101.

[0065] The housing 120 has, on its surface, an abutment surface 121 that comes into surface contact with the mounting surface 1021 of the substrate 102 of the reading unit 104, and an abutment surface 122 that comes into surface contact with the abutment surface 201 of the lens mirror array 20. The housing 120 is formed from a single member such as a synthetic resin with a low thermal expansion coefficient. In the illustrated state in which the reading unit 104 and the lens mirror array 20 are fixed to the housing 120, the two abutment surfaces 121, 122 of the housing 120, the mounting surface 1021 of the reading unit 104, and the abutment surface 201 of the lens mirror array 20 are planes that are perpendicular to the optical axis direction of the lens mirror array 20.

[0066] That is, in the document reading device 10, as in the solid-state head 504 described above, the reading unit 104 and the lens mirror array 20 can be positioned with high precision in the optical axis direction, and good optical characteristics can be obtained.

[0067] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel 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. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0068] 10... document reading device, 20... lens mirror array, 201, 202, 203, 204... contact surface, 21... optical element, 22... incident side lens surface, 23... upstream side reflective surface, 24... downstream side reflective surface, 25... exit side lens surface, 314... photosensitive drum, 52... light source unit, 521... light emitting element, 522... substrate, 5221... mounting surface, 54... holder, 5421, 5422, 5423, 5424, 5425... contact surface, 504... solid head, 80... holder, 81... fixing member, 82... support member, 90... light source unit, 921... surface, 100... image forming device, 101... image sensor, 102... substrate, 104... reading unit, 120 housing.

Claims

1. a light source unit including a light source that emits light in a first direction and having a first positioning surface on a surface thereof that is perpendicular to the first direction; an optical member disposed opposite to and spaced apart from each other in the first direction of the light source unit, the optical member having, on its surface, an incident surface into which light emitted from the light source is incident, an exit surface from which the light incident via the incident surface is exited, and a second positioning surface orthogonal to the first direction and provided at a position overlapping with the first positioning surface in the first direction; a single-member holder having, on its surface, a third positioning surface that comes into surface contact with the first positioning surface, and a fourth positioning surface that comes into surface contact with the second positioning surface and is provided at a position that overlaps with the third positioning surface in the first direction, the holder holding the light source unit with the first positioning surface of the light source unit in surface contact with the third positioning surface, and the holder holding the optical member with the second positioning surface of the optical member in surface contact with the fourth positioning surface; An optical device having:

2. the light source unit includes a plurality of light-emitting elements serving as the light source and a substrate on which the plurality of light-emitting elements are mounted and arranged in a second direction perpendicular to the first direction, the first positioning surface is a mounting surface of the substrate; The optical device according to claim 1 .

3. the optical member is a lens mirror array having a plurality of optical elements arranged in the second direction, each of the plurality of optical elements having an incident-side lens surface which is the incident surface, an exit-side lens surface which is the exit surface, and a reflecting surface which reflects light incident through the incident-side lens surface toward the exit-side lens surface.

3. The optical device according to claim 2.

4. the second positioning surface is on a surface of the lens mirror array between the reflective surfaces and the output lens surfaces of the plurality of optical elements; 4. The optical device according to claim 3.

5. the optical member has a fifth positioning surface on a surface thereof that is perpendicular to the second positioning surface, the holder has a sixth positioning surface on a surface thereof that is in surface contact with the fifth positioning surface; 4. The optical device according to claim 3.

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