Light receiving lens array, optical line sensor, and method for manufacturing light receiving lens array

Abstract

A light receiving lens array (11) for imaging light from an object on a read line extending along a main scanning direction is provided with a plurality of light receiving lenses (111) and a pair of holding plates (112). The plurality of light receiving lenses 111 are arranged in the main scanning direction. Each of the pair of holding plates 112 extends in the main scanning direction, and sandwiches the plurality of light receiving lenses 111 in the sub-scanning direction. Each of the light-receiving lenses 111 has a first surface and a second surface that are in contact with the pair of holding plates 112, respectively.

Description

Technical Field

[0001] The present invention relates to a light receiving lens array for imaging light from an object on a reading line extending along a main scanning direction, an optical line sensor including the light receiving lens array, and a method for manufacturing the light receiving lens array. Background Art

[0002] In an image reading device having an optical line sensor, light is irradiated from a light source toward an object, and reflected light or transmitted light from the object is imaged on a reading line through a light receiving lens, and is thus received by a light receiving element on the reading line. A plurality of light receiving lenses are arranged, and light transmitted through each light receiving lens is received by a plurality of light receiving elements (for example, refer to Patent Document 1 below).

[0003] Usually, a plurality of light-receiving lenses are held as a whole by a frame. In the example of Patent Document 1, the frame is composed of a large number of frame parts, and a light-receiving lens is held in each frame part. A gap is provided between each frame part to prevent the relative position from deviating due to temperature changes.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: International Publication No. 2021 / 049177 Summary of the invention

[0007] Problems to be solved by the invention

[0008] However, in the above-mentioned conventional structure, since a large number of frame parts are required and the shapes of the frame parts are complicated, there is a problem that the manufacturing cost of the parts becomes high. In addition, there is also a problem that the assembly work becomes complicated due to the large number of parts.

[0009] The present invention has been made in view of the above-mentioned actual situation, and an object of the present invention is to provide a light receiving lens array and an optical line sensor having a small number of parts and easy assembly work, and a method for manufacturing the light receiving lens array.

[0010] Means used to solve problems

[0011] (1) The light receiving lens array involved in the present invention is a light receiving lens array for imaging light from an object on a reading line extending along a main scanning direction, and the light receiving lens array includes a plurality of light receiving lenses and a pair of retaining plates. The plurality of light receiving lenses are arranged in the main scanning direction. The pair of retaining plates extend along the main scanning direction and clamp the plurality of light receiving lenses in the sub-scanning direction. Each light receiving lens has a first surface and a second surface respectively abutting against the pair of retaining plates.

[0012] According to such a configuration, a plurality of light receiving lenses can be clamped by a pair of holding plates while the first and second surfaces of each light receiving lens are in contact with each of the pair of holding plates. Therefore, since a large number of frame parts are not required, the number of parts is small and the assembly operation is easy.

[0013] (2) The first surface and the second surface of each light receiving lens may be bonded to the pair of holding plates, respectively.

[0014] According to such a configuration, each light receiving lens can be held by the pair of holding plates in a simple configuration in which the first surface and the second surface of each light receiving lens are merely bonded to the pair of holding plates. Therefore, the number of components is reduced and the assembly operation is easy.

[0015] (3) The plurality of light receiving lenses may be arranged with spaces spaced apart from each other so that the light receiving lenses adjacent to each other in the main scanning direction do not contact each other.

[0016] According to such a configuration, even when each light receiving lens is deformed due to temperature change, forces do not interact between the light receiving lenses, and relative positional deviation of the light receiving lenses can be suppressed.

[0017] (4) An elastic member having light-shielding properties and low reflectivity may be provided in the space.

[0018] According to such a configuration, the contact between the light receiving lenses can be avoided by the elastic member, and stray light can be suppressed and the intrusion of dust can be prevented.

[0019] (5) The light receiving lens array may further include an aperture member having an opening through which light passing through the light receiving lens passes. In this case, the width of the aperture member in the sub-scanning direction may be equal to the distance between the first surface and the second surface.

[0020] According to such a configuration, in a state where the two end surfaces of the aperture member in the sub-scanning direction are respectively in contact with the pair of holding plates, a plurality of light-receiving lenses can be clamped by the pair of holding plates. In this way, the two end surfaces of each light-receiving lens in the sub-scanning direction and the two end surfaces of the aperture member in the sub-scanning direction are respectively in contact with the pair of holding plates, thereby enabling the plurality of light-receiving lenses to be stably clamped by the pair of holding plates.

[0021] (6) The aperture member may have a truncated cone-shaped opening.

[0022] According to such a configuration, it is possible to guide the light from each light receiving lens toward the aperture member along the truncated cone-shaped opening.

[0023] (7) In the aperture member, the opening and the pinhole through which the light passing through the opening enters may be formed to face each other with a gap therebetween.

[0024] According to such a configuration, it is possible to guide light from each light receiving lens toward the aperture member along the opening and the pinhole.

[0025] (8) The aperture member may be provided with a light shielding portion that closes a portion of the opening to prevent intrusion of stray light.

[0026] According to such a configuration, the light shielding portion can prevent stray light from intruding into the optical path from each light receiving lens to the aperture member.

[0027] (9) The optical axis of the light receiving lens may be offset in the sub-scanning direction with respect to the reading line.

[0028] According to this configuration, the light shielding portion can effectively shield stray light emitted from the adjacent light receiving lens and directed toward the opening in a direction inclined toward the sub-scanning direction relative to a direction orthogonal to the main scanning direction and the sub-scanning direction.

[0029] (10) Each light receiving lens may be formed into a trapezoid having the first surface, the second surface having a width smaller than the first surface in the main scanning direction, and a pair of inclined surfaces connecting the first surface and the second surface. In this case, the inclined surfaces of the light receiving lenses adjacent to each other in the main scanning direction may be opposite to each other.

[0030] According to such a configuration, the light receiving lenses formed in a trapezoidal shape can be efficiently arranged in the main scanning direction.

[0031] (11) The optical axes of the plurality of light receiving lenses may all be located on the same plane and parallel to each other.

[0032] According to such a configuration, light from an object can be imaged on a reading line by a plurality of light receiving lenses arranged in a row.

[0033] (12) The optical line sensor according to the present invention includes: the light receiving lens array; and a plurality of light receiving elements that receive light that has passed through the plurality of light receiving lenses.

[0034] According to such a configuration, it is possible to provide an optical line sensor including a light receiving lens array with a small number of components and easy assembly work.

[0035] (13) Another optical line sensor according to the present invention comprises: the light receiving lens array; and a plurality of light receiving elements that receive light transmitted through the plurality of light receiving lenses, wherein the plurality of light receiving elements constitute a plurality of light receiving element arrays extending along the main scanning direction. The plurality of light receiving element arrays are alternately arranged on two columns of the reading lines, and the optical axes of the plurality of light receiving lenses are arranged in the middle of the two columns of the reading lines.

[0036] According to such a configuration, by staggeredly arranging a plurality of light receiving element arrays on two columns of reading lines, it is possible to avoid a state where there are no pixels between the ends of adjacent light receiving element arrays in the main scanning direction. The ends of the light receiving element arrays may be arranged to overlap with each other in the sub-scanning direction, or may be arranged continuously along the main scanning direction within a range where they do not overlap with each other. In the case where the ends of the light receiving element arrays are arranged to overlap with each other in the sub-scanning direction, if the light receiving lenses are formed into a trapezoidal configuration, the light receiving lenses can be effectively arranged in the main scanning direction in association with the light receiving element arrays.

[0037] (14) The manufacturing method of the light-receiving lens array involved in the present invention is a manufacturing method of the light-receiving lens array, and the manufacturing method of the light-receiving lens array includes a first lens installation step, a second lens installation step and a fixing step. In the first lens installation step, a part of the plurality of light-receiving lenses is installed on one side of the pair of retaining plates in a manner separated in the main scanning direction. In the second lens installation step, the remaining parts of the plurality of light-receiving lenses are installed on the other side of the pair of retaining plates in a manner separated in the main scanning direction. In the fixing step, the pair of retaining plates are made to face each other, and each light-receiving lens is clamped and fixed in the sub-scanning direction by the pair of retaining plates, so that the plurality of light-receiving lenses installed on the other side of the pair of retaining plates are inserted between the plurality of light-receiving lenses installed on one side of the pair of retaining plates.

[0038] According to such a structure, a part of a plurality of light receiving lenses is installed on one side of a pair of retaining plates, and the rest of the plurality of light receiving lenses is installed on the other side of a pair of retaining plates, and these pairs of retaining plates are made to face each other. Each light receiving lens can be clamped only by a pair of retaining plates. Since there is no need to use a large number of frame components, the number of components is small and the assembly operation is easy.

[0039] (15) Each light-receiving lens may be formed into a trapezoid having the first surface, the second surface whose width in the main scanning direction is smaller than that of the first surface, and a pair of inclined surfaces connecting the first surface and the second surface. In this case, in the first lens mounting step, the first surface of a part of the plurality of light-receiving lenses may be mounted on one of the pair of retaining plates. In addition, in the second lens mounting step, the first surface of the remaining part of the plurality of light-receiving lenses may be mounted on the other of the pair of retaining plates.

[0040] According to such a configuration, the root side (first surface side) of each light-receiving lens formed into a trapezoid is mounted on a pair of retaining plates, and the pair of retaining plates are made to face each other, thereby enabling the front end side (second surface side) of each light-receiving lens to enter between the light-receiving lenses, thereby clamping each light-receiving lens by the pair of retaining plates. Therefore, even when using a light-receiving lens formed into a trapezoid, the assembly operation is easy.

[0041] (16) The light receiving lens array may further include an aperture member having an opening formed therein for light passing through the light receiving lens. In this case, in the first lens mounting step and the second lens mounting step, the plurality of light receiving lenses and the aperture member may be mounted on the pair of retaining plates using a fixture for positioning the plurality of light receiving lenses and the aperture member at predetermined positions.

[0042] According to such a configuration, the plurality of light receiving lenses and the aperture member can be positioned at predetermined positions using a jig, so that the assembly work is easy.

[0043] Effects of the Invention

[0044] According to the present invention, it is possible to provide a light receiving lens array and an optical line sensor which have a small number of parts and are easy to assemble, and a method for manufacturing the light receiving lens array. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a cross-sectional view showing a configuration example of an optical line sensor according to an embodiment of the present invention.

[0046] Figure 2 Yes Figure 1 An exploded perspective view showing an example of the configuration of an illumination optical system in an optical line sensor.

[0047] Figure 3 It is a diagram for explaining the first embodiment of the light receiving lens array, and is a perspective view of the light receiving lens array according to the first embodiment.

[0048] Figure 4It is a diagram for explaining the first embodiment of the light receiving lens array, and is an exploded perspective view of the light receiving lens array according to the first embodiment.

[0049] Figure 5 It is a diagram for explaining the first embodiment of the light receiving lens array and is a perspective view of an aperture member according to the first embodiment.

[0050] Figure 6 It is a diagram for explaining the second embodiment of the light receiving lens array, and is a perspective view of the light receiving lens array according to the second embodiment.

[0051] Figure 7 It is a diagram for explaining the second embodiment of the light receiving lens array, and is an exploded perspective view of the light receiving lens array according to the second embodiment.

[0052] Fig. 8A It is a diagram for explaining the second embodiment of the light receiving lens array and is a perspective view of an aperture member according to the second embodiment.

[0053] Figure 8B This is a perspective view showing a modified example of the aperture member according to the second embodiment.

[0054] Fig. 9 It is a perspective view for explaining the method for manufacturing the light receiving lens array according to the second embodiment.

[0055] Fig. 10A is a schematic diagram for explaining the positional relationship between the light receiving lens and the light receiving element array, showing Figure 6 as well as Figure 7 The case of a trapezoidal light receiving lens according to the second embodiment shown.

[0056] Fig. 10B It is a schematic diagram for explaining the positional relationship between a light receiving lens and a light receiving element array, and shows a light receiving lens according to a modified example. DETAILED DESCRIPTION

[0057] 1. Overall structure of optical line sensor

[0058] Figure 1 This is a cross-sectional view showing a configuration example of an optical line sensor according to an embodiment of the present invention. Figure 1 , a cross-sectional view of the optical line sensor near the longitudinal center is shown. Figure 2 Yes Figure 1 This is an exploded perspective view showing an example of the configuration of an illumination optical system in an optical line sensor. Figure 2In the embodiment, the X direction is the main scanning direction, the Y direction is the sub-scanning direction, and the Z direction is orthogonal to the X direction and the Y direction.

[0059] This optical line sensor is a contact image sensor (CIS) that irradiates light onto thin objects such as printed materials and films, and receives reflected light or transmitted light from the object through a light receiving element. Figure 1 In the optical line sensor shown, two frames 16 are arranged opposite to each other with a focal plane 20 in between. A linear light source unit 10 for illuminating an object located on the focal plane 20 is provided in each frame 16. A light receiving lens array 11 and a light receiving element array 12 are provided in one frame 16, and light from the illuminated object is guided to the light receiving element array 12 through the light receiving lens array 11. The light receiving lens array 11 images the light from the object onto the light receiving element array 12 on a reading line extending along the X direction. Figure 1 In the optical line sensor shown, one of the two light source units 10 is arranged on the light receiving element array 12 side and the other is arranged on the side opposite to the light receiving element array 12, based on the focal plane 20. In addition, a protective glass 14 is provided in the opening of each frame 16 on the focal plane 20 side.

[0060] The light receiving element array 12 is mounted on a substrate 13 fixed to one of the frames 16. The light passing through the light receiving lens array 11 is received by the light receiving surface 12A of the light receiving element array 12, and a signal corresponding to the amount of light received is output from the light receiving element array 12. By transporting the object in the Y direction along the focal plane 20, the light from the object is continuously received by the light receiving element array 12, and an image of the object is obtained based on the output signal from the light receiving element array 12. In this way, the light receiving element array 12 extending in the X direction reads the object transported in the Y direction using the reading line formed by the light receiving surface 12A of the light receiving element array 12.

[0061] An ultraviolet light blocking filter (UV cut filter) 15 that blocks ultraviolet light from entering the light receiving element array 12 may be provided at any position from the focal plane 20 to the light receiving element array 12. In addition, a color filter 18 that allows visible light in a specific wavelength range to pass may be provided between the light receiving element array 12 and the ultraviolet light blocking filter 15.

[0062] exist Figure 1 as well as Figure 2In the example shown, the light source unit 10 includes: a transparent light guide 101 extending in the longitudinal direction (X direction); a light source 103 provided near one end surface in the longitudinal direction; and a cover member 102 for holding the side surfaces of the light guide 101. After the light emitted from the light source 103 enters the light guide 101, it is appropriately reflected by the light diffusion pattern P while propagating in the light guide 101, and is emitted from the light emission surface in the direction of the arrow, forming linear illumination light to illuminate the object.

[0063] 2. First Embodiment of the Light Receiving Lens Array

[0064] Figure 3 to Figure 5 This is a diagram for explaining a first embodiment of the light receiving lens array 11 . Figure 3 It is a perspective view of the light receiving lens array 11 according to the first embodiment. Figure 4 It is an exploded perspective view of the light receiving lens array 11 according to the first embodiment. Figure 5 It is a perspective view of the aperture member 113 according to the first embodiment.

[0065] The light receiving lens array 11 includes a plurality of light receiving lenses 111 and a pair of retaining plates 112. The plurality of light receiving lenses 111 are arranged in a straight line along the X direction. In more detail, the optical axes of the plurality of light receiving lenses 111 are all located on the same plane and are parallel to each other. The pair of retaining plates 112 are respectively rectangular thin plate members extending parallel to each other along the X direction. The plurality of light receiving lenses 111 are clamped between the pair of retaining plates 112 in the Y direction. In the case where it is desired to increase the X-direction dimension of the retaining plate 112, in order to suppress the length change accompanying the temperature change, it is best to select a material with a small linear expansion coefficient. For example, it is therefore preferred that the linear expansion coefficient of the glass epoxy laminate is as small as a linear expansion coefficient of about 16 ppm, and the specific gravity is also small, so that the weight can be suppressed.

[0066] Each light receiving lens 111 is rectangular in a plan view (viewed in the Z direction), and one end face (first face 111A) and the other end face (second face 111B) in the Y direction are respectively formed of flat surfaces. The incident surface (surface on the focal plane 20 side) and the exit surface (surface opposite to the incident surface) of each light receiving lens 111 are formed of, for example, convex curved surfaces, which play a role in imaging the light incident to each light receiving lens 111 on the light receiving surface 12A.

[0067] The widths of the light-receiving lenses 111 in the Y direction (the interval between the first surface 111A and the second surface 111B) are consistent. Therefore, the plurality of light-receiving lenses 111 can be integrally clamped by a pair of holding plates 112, so that the first surface 111A of each light-receiving lens 111 abuts against one side of the pair of holding plates 112 (holding plate 112A), and the second surface 111B of each light-receiving lens 111 abuts against the other side of the pair of holding plates 112 (holding plate 112B).

[0068] In this embodiment, the light receiving lens array 11 includes a plurality of aperture members 113. Each aperture member 113 is associated with each light receiving lens 111 one by one and is arranged separately from each light receiving lens 111 in the optical axis direction. Light transmitted through each light receiving lens 111 passes through an opening 113A formed in the corresponding aperture member 113 and is guided to the light receiving element array 12. Figure 5 As shown, the opening 113A formed in the aperture member 113 passes through the aperture member 113 in the optical axis direction, and is formed into a truncated cone shape with a pointed front end from the light receiving lens 111 side toward the light receiving element array 12 side. The Z direction (optical axis direction) position of the pointed front end side of the opening 113A can be made consistent with the image side focus of the light receiving lens 111 to form a telecentric optical system. At this time, it is preferred to make the vertex angle of the truncated cone-shaped opening 113A slightly larger than the opening angle of the light receiving lens 111. As a result, the image formed by the light receiving lens 111 will not produce vignetting, and stray light can be effectively reduced.

[0069] The width of each aperture member 113 in the Y direction is consistent with the interval between the first surface 111A and the second surface 111B of each light receiving lens 111. That is, the width of each aperture member 113 in the Y direction is consistent with the width of each light receiving lens 111 in the Y direction. Therefore, when the plurality of light receiving lenses 111 are integrally clamped by a pair of holding plates 112, the two end surfaces of each aperture member 113 in the Y direction are respectively in contact with the pair of holding plates 112.

[0070] In the present embodiment, the first surface 111A of each light-receiving lens 111 is bonded to the retaining plate 112A on one side, and the second surface 111B is bonded to the retaining plate 112B on the other side. Similarly, the surface on one side of the Y direction of each aperture member 113 is bonded to the retaining plate 112A on one side, and the surface on the other side of the Y direction is bonded to the retaining plate 112B on the other side. The components can be bonded together using a general adhesive or double-sided tape. However, each aperture member 113 may not be a member independent of a pair of retaining plates 112, but may be formed integrally with the retaining plate 112 on either side.

[0071] Each light receiving lens 111 may not be bonded as long as it abuts against a pair of holding plates 112. For example, a convex portion may be formed on a portion of the first surface 111A and the second surface 111B of the light receiving lens 111, and a concave portion corresponding to the convex portion may be formed on the pair of holding plates 112. When each concave portion is embedded in each convex portion, the pair of holding plates 112 are fixed to each other by a fixing member, thereby clamping each light receiving lens 111 in the Y direction by the pair of holding plates 112.

[0072] It is preferred that each light receiving lens 111 is configured not to contact each other. That is, a plurality of light receiving lenses 111 can be arranged with spaces between each other in a manner that the light receiving lenses 111 adjacent to each other in the X direction do not contact each other. In this case, it is preferred that an elastic member having light shielding properties and low reflectivity is provided in the space. As the elastic member, polyurethane is listed, but it is not limited thereto, and an elastic member can also be formed between each light receiving lens 111 by filling an elastic adhesive or the like.

[0073] 3. Second Embodiment of the Light Receiving Lens Array

[0074] Figures 6 to 8A This is a diagram for explaining a second embodiment of the light receiving lens array 11 . Figure 6 It is a perspective view of the light receiving lens array 11 according to the second embodiment. Figure 7 It is an exploded perspective view of the light receiving lens array 11 according to the second embodiment. Fig. 8A It is a perspective view of the aperture member 113 according to the second embodiment.

[0075] The light receiving lens array 11 includes a plurality of light receiving lenses 111 and a pair of retaining plates 112. The plurality of light receiving lenses 111 are arranged in a straight line along the X direction. In more detail, the optical axes of the plurality of light receiving lenses 111 are all located on the same plane and are parallel to each other. The pair of retaining plates 112 are rectangular thin plate members, extending parallel to each other along the X direction. The plurality of light receiving lenses 111 are clamped between the pair of retaining plates 112 in the Y direction.

[0076] Each light-receiving lens 111 is trapezoidal in a top view (observation in the Z direction), and the end face on one side in the Y direction (the first face 111A) and the end face on the other side (the second face 111B) are respectively formed by flat surfaces. The width of the second face 111B in the X direction is smaller than the width of the first face 111A, and the second face 111B is opposite to the central portion of the first face 111A in the X direction. The first face 111A and the second face 111B are connected by a pair of inclined surfaces 111C. That is, one end of the first face 111A in the X direction is connected to one end of the second face 111B in the X direction by the inclined surface 111C on one side, and the other end of the first face 111A in the X direction is connected to the other end of the second face 111B in the X direction by the inclined surface 111C on the other side.

[0077] The incident surface (surface on the focal plane 20 side) and the emitting surface (surface opposite to the incident surface) of each light receiving lens 111 are composed of, for example, convex curved surfaces, which play a role in imaging the light incident on each light receiving lens 111 on the light receiving surface 12A. In this example, each light receiving lens 111 is composed of two trapezoidal lenses (biconvex lens and meniscus lens) arranged side by side on the optical axis along the Z direction, but is not limited to such a structure, and each light receiving lens 111 can also be composed of one trapezoidal lens, or can be composed of three or more trapezoidal lenses.

[0078] like Figure 7 As shown, the plurality of light-receiving lenses 111 include a light-receiving lens 111 (light-receiving lens 120) mounted on a portion of one of a pair of retaining plates 112 (retaining plate 112A), and a light-receiving lens 111 (light-receiving lens 130) mounted on the other of the pair of retaining plates 112 (retaining plate 112B). The first surface 111A of each light-receiving lens 111 is mounted on each retaining plate 112. That is, the method for manufacturing the light-receiving lens array 11 in this example includes: a first lens mounting step, in which the first surface 111A of a portion of the plurality of light-receiving lenses 111 (light-receiving lens 120) is mounted on one of the pair of retaining plates 112 (retaining plate 112A); and a second lens mounting step, in which the first surface 111A of the remaining portion of the plurality of light-receiving lenses 111 (light-receiving lens 130) is mounted on the other of the pair of retaining plates 112 (retaining plate 112B).

[0079] In the first lens mounting step, half of the plurality of light receiving lenses 111 (light receiving lenses 120) are mounted on one side (holding plate 112A) of the pair of holding plates 112 in a manner of mounting every other lens in the X direction. In the second lens mounting step, the remaining half of the plurality of light receiving lenses 111 (light receiving lenses 130) are mounted on the other side (holding plate 112B) of the pair of holding plates 112 in a manner of mounting every other lens in the X direction. In essence, since the first lens mounting step and the second lens mounting step are the same operation, the workability is improved and the types of assembly jigs are reduced.

[0080] As described above, after each half of the plurality of light receiving lenses 111 is mounted on each of the pair of holding plates 112, the pair of holding plates 112 are made to face each other, and the light receiving lenses 111 are clamped in the Y direction by the pair of holding plates 112, thereby fixing the light receiving lenses 111 between the pair of holding plates 112 (fixing step). In this fixing step, Figure 6 as well as Figure 7 As shown, a plurality of light receiving lenses (light receiving lenses 130) mounted on the other side (holding plate 112B) of the pair of holding plates 112 are inserted between a plurality of light receiving lenses 111 (light receiving lenses 120) mounted on one side (holding plate 112A) of the pair of holding plates 112. In this state, the inclined surfaces 111C of the light receiving lenses 111 (light receiving lenses 120 and light receiving lenses 130) adjacent in the X direction face each other.

[0081] The widths in the Y direction (the interval between the first surface 111A and the second surface 11B) of each light-receiving lens 111 are consistent. Therefore, the plurality of light-receiving lenses 111 are integrally clamped by a pair of retaining plates 112, so that the first surface 111A of each light-receiving lens 111 can be brought into contact with one side of the pair of retaining plates 112 (the light-receiving lens 120 is brought into contact with the retaining plate 112A, and the light-receiving lens 130 is brought into contact with the retaining plate 112B), and the second surface 111B of each light-receiving lens 111 can be brought into contact with the other side of the pair of retaining plates 112 (the light-receiving lens 120 is brought into contact with the retaining plate 112B, and the light-receiving lens 130 is brought into contact with the retaining plate 112A).

[0082] In this embodiment, the light receiving lens array 11 includes a plurality of aperture members 113. Each aperture member 113 is associated with each light receiving lens 111 one by one and is arranged separately from each light receiving lens 111 in the optical axis direction. Light transmitted through each light receiving lens 111 passes through an opening 113A formed in the corresponding aperture member 113 and is guided to the light receiving element array 12. Fig. 8AAs shown, the opening 113A formed in the aperture member 113 passes through the aperture member 113 in the optical axis direction, and is formed into a truncated cone shape with a pointed front end from the light receiving lens 111 side toward the light receiving element array 12 side. The Z direction (optical axis direction) position of the pointed front end side of the opening 113A can be made consistent with the image side focus of the light receiving lens 111 to form a telecentric optical system. At this time, it is preferred that the top angle of the truncated cone-shaped opening 113A is slightly larger than the opening angle of the light receiving lens 111. As a result, the image formed by the light receiving lens 111 will not produce vignetting, and stray light can be effectively reduced.

[0083] In this example, if Fig. 8A As shown, the aperture member 113 is provided with a light shielding portion 113B that blocks a portion of the opening 113A to prevent the intrusion of stray light. In this example, the half of the truncated cone-shaped opening 113A in the Y direction (the portion through which stray light passes) is closed, thereby forming a semi-truncated cone-shaped opening 113A having a semicircular arc surface and a flat surface. A recessed portion 113C extending along the optical axis direction is formed on the above-mentioned flat surface constituting the light shielding portion 113B. The recessed portion 113C can be formed like Fig. 8A That's a semi-cylindrical shape.

[0084] The width of each aperture member 113 in the Y direction is consistent with the interval between the first surface 111A and the second surface 111B of each light receiving lens 111. That is, the width of each aperture member 113 in the Y direction is consistent with the width of each light receiving lens 111 in the Y direction. Therefore, when the plurality of light receiving lenses 111 are integrally clamped by a pair of holding plates 112, the two end surfaces of each aperture member 113 in the Y direction are respectively in contact with the pair of holding plates 112.

[0085] In the present embodiment, the first surface 111A of the light-receiving lens 120 is bonded to the retaining plate 112A, and the second surface 111B is bonded to the retaining plate 112B. In addition, the first surface 111A of the light-receiving lens 130 is bonded to the retaining plate 112B, and the second surface 111B is bonded to the retaining plate 112A. Similarly, the surface of each aperture component 113 on one side of the Y direction is bonded to the retaining plate 112A on one side, and the surface of the other side of the Y direction is bonded to the retaining plate 112B on the other side. The components can be bonded together using a general adhesive or double-sided tape. However, each aperture component 113 may not be a component independent of a pair of retaining plates 112, but may be formed integrally with the retaining plate 112 of either side.

[0086] Each light receiving lens 111 may not be bonded as long as it abuts against a pair of holding plates 112. For example, a convex portion may be formed on a portion of the first surface 111A and the second surface 111B of the light receiving lens 111, and a concave portion corresponding to the convex portion may be formed on the pair of holding plates 112. With each convex portion embedded in each concave portion, the pair of holding plates 112 may be fixed to each other by a fixing member, thereby clamping each light receiving lens 111 in the Y direction by the pair of holding plates 112.

[0087] It is preferred that each light-receiving lens 111 is configured not to contact each other. That is, the plurality of light-receiving lenses 111 can be arranged spaced apart from each other in a manner that the inclined surfaces 111C of the light-receiving lenses 111 adjacent in the X direction do not contact each other. In this case, it is preferred that an elastic member having light-shielding properties and low reflectivity is provided in the space. As the elastic member, polyurethane is listed, but it is not limited thereto, and the elastic member can be formed between the light-receiving lenses 111 by filling an elastic adhesive or the like.

[0088] Figure 8B 1 is a perspective view showing a modified example of the aperture member 113 according to the second embodiment. Fig. 8A In the example of FIG. 1 , the aperture member 113 is constituted by a quadrangular columnar member and a truncated cone-shaped opening 113A is formed to penetrate the member. Figure 8B In the example of FIG. 1 , the aperture member 113 is composed of a rectangular frame, and two openings 113D and 113E are formed in the member so as to face each other.

[0089] Specifically, Figure 8B The aperture member 113 has an upper surface plate and a lower surface plate extending in the horizontal direction in a manner that is opposed to each other in the vertical direction, and a pair of side panels extending in the vertical direction in a manner that the two ends of the upper surface plate and the lower surface plate are connected to each other, and has a shape framed into a rectangular shape when viewed in the horizontal direction. The upper surface plate and the lower surface plate are arranged in parallel with each other at a distance, and an opening 113D is formed in the upper surface plate, and an opening 113E is formed in the lower surface plate. Thus, the opening 113D and the opening 113E are formed to be opposed to each other at a distance.

[0090] The opening 113E is configured so that the position in the Z direction (optical axis direction) coincides with the image-side focal point of the light-receiving lens 111. Thus, a telecentric optical system is formed. Figure 8BAs shown, the aperture member 113 is provided with a light shielding portion 113B that blocks a portion of the opening 113D to prevent the intrusion of stray light. In this example, the half of the circular opening in the Y direction (the portion through which stray light passes) is blocked, thereby forming a semicircular opening 113D having a semicircular surface and a flat surface. Fig. 8A Similarly to the example of , a semicircular recess extending along the optical axis direction may be formed. Opening 113E is a circular pinhole smaller than opening 113D, and is used for light passing through opening 113D to enter. At this time, it is preferred that the top angle of the truncated cone virtualy formed by opening 113D and opening 113E is slightly larger than the opening angle of light receiving lens 111. As a result, the image formed by light receiving lens 111 will not produce vignetting, and stray light can be effectively reduced.

[0091] As described below Fig. 10A or Fig. 10B As in the example of , when the optical axis of each light-receiving lens 111 deviates from the light-receiving element array 12 (reading line L) in the Y direction, the light-shielding portion 113B can effectively shield the stray light emitted from the adjacent light-receiving lens 111 and directed toward the opening 113E in a direction inclined in the Y direction relative to the Z direction (a direction orthogonal to the X direction and the Y direction). In this case, a partition plate may not be provided between the adjacent light-receiving lenses 111 and the aperture member 113. In addition, the side panels of the aperture member 113 can be omitted, and the aperture member 113 can be formed by an upper surface plate and a lower surface plate separated from each other, but if Figure 8B By forming the aperture member 113 in the frame body in this manner, the aperture member 113 becomes an integrated structure, and thus is easy to handle.

[0092] Fig. 9 This is a stereogram for explaining the manufacturing method of the light receiving lens array 11 involved in the second embodiment. When manufacturing the light receiving lens array 11, the light receiving lenses 111 and the aperture members 113 are mounted on the holding plate 112 while the holding plate 112 is placed on the mounting table 200 (first lens mounting step and second lens mounting step).

[0093] The mounting table 200 is provided with a first positioning portion 201 and a pressing mechanism 202. The first positioning portion 201 is formed by a plurality of protrusions, and the side edge of the holding plate 112 is brought into contact with the side surface of the first positioning portion 201, thereby enabling the holding plate 112 to be positioned. When the holding plate 112 is positioned, the holding plate 112 is pressed by the pressing mechanism 202, thereby fixing the holding plate 112 to the mounting table 200. In this example, a pair of pressing mechanisms 202 are provided, which can press the two ends of the holding plate 112 in the longitudinal direction. However, the first positioning portion 201 is not limited to a positioning portion formed by a protrusion, and may be a positioning portion formed by a recess, for example.

[0094] In the first lens mounting step and the second lens mounting step, the plurality of light receiving lenses 111 and the aperture member 113 are mounted on a pair of holding plates 112 using an optical axis alignment jig 300. The optical axis alignment jig 300 is a jig for positioning the light receiving lenses 111 and the aperture member 113 at predetermined positions and aligning the optical axes thereof.

[0095] A second positioning portion 203 for positioning the optical axis alignment fixture 300 is formed on the mounting table 200. The second positioning portion 203 is composed of a plurality of protrusions. Specifically, a pair of protrusions corresponding to the pair of light-receiving lenses 111 and aperture members 113 are arranged in a plurality of pairs along the X direction. The spacing (pitch) in the X direction between the plurality of pairs of protrusions is consistent with the spacing (pitch) in the X direction when each light-receiving lens 111 and each aperture member 113 is mounted on the retaining plate 112. However, the second positioning portion 203 is not limited to a positioning portion composed of protrusions, and may be, for example, a positioning portion composed of a recess.

[0096] The optical axis alignment jig 300 is a plate-shaped member, and is used in a state of being placed on the holding plate 112 mounted on the mounting table 200. The optical axis alignment jig 300 has a first through hole 301, a second through hole 302, and a third through hole 303 formed therein.

[0097] The first through hole 301 is a hole for inserting the light receiving lens 111, and has a shape that abuts against and positions the positioning portion of the light receiving lens 111. The second through hole 302 is a hole for inserting the aperture member 113, and has a shape that abuts against and positions the positioning portion of the aperture member 113. The third through hole 303 has a shape corresponding to a pair of protrusions constituting the second positioning portion 203, and a pair of third through holes 303 are formed that are separated by the same interval as the pair of protrusions.

[0098] When manufacturing the light receiving lens array 11, the optical axis alignment jig 300 is placed on the holding plate 112 while the holding plate 112 is fixed to the mounting table 200 by the pressing mechanism 202. At this time, the plurality of pairs of protrusions constituting the second positioning portion 203 are sequentially inserted into a pair of third through holes 303 of the optical axis alignment jig 300 for each pair of protrusions.

[0099] Then, in a state where each pair of protrusions is inserted into a pair of third through holes 303 of the optical axis alignment jig 300, the light receiving lens 111 is inserted into and positioned in the first through hole 301 and mounted on the holding plate 112, and the aperture member 113 is inserted into and positioned in the second through hole 302 and mounted on the holding plate 112. At this time, the light receiving lens 111 is inserted into the first through hole 301 in a state where an adhesive is applied to the contact surface with the holding plate 112. In addition, the aperture member 113 is inserted into the second through hole 302 in a state where an adhesive is applied to the contact surface with the holding plate 112. As another method, if adhesive is applied to one side of the holding plate 112 or double-sided tape is attached in advance, the work of applying adhesive to the light receiving lens 111 and the aperture member 113 can be omitted.

[0100] In this way, the light receiving lens 111 and the aperture member 113 can be mounted on the holding plate 112 at positions corresponding to the respective pairs of protrusions constituting the second positioning portion 203. Figure 7 In this way, the plurality of light receiving lenses 111 and the plurality of aperture members 113 are attached to each holding plate 112 at intervals along the X direction.

[0101] 4. Positional relationship between the light receiving lens and the light receiving element array

[0102] Fig. 10A as well as Fig. 10B This is a schematic diagram for explaining the positional relationship between the light receiving lens 111 and the light receiving element array 12 . Fig. 10A Shows Figure 6 as well as Figure 7 The case of the trapezoidal light receiving lens 111 according to the second embodiment shown in FIG. Fig. 10B The light receiving lens 111 according to a modified example is shown.

[0103] exist Fig. 10A as well as Fig. 10B In the description, a layout is described in which a plurality of light receiving lenses 111 are arranged in one row along the X direction and the light receiving element arrays 12 are arranged in two rows in a staggered manner. Fig. 10A as well as Fig. 10BIn the embodiment, a plurality of light receiving element arrays 12 extending along the X direction are arranged alternately on two columns of reading lines L. Each light receiving element array 12 has a plurality of light receiving elements arranged in parallel in its length direction (X direction). Light passing through each light receiving lens 111 is received by a plurality of light receiving elements in the light receiving element array 12 corresponding to each light receiving lens 111. The optical axis of each light receiving lens 111 is arranged in the middle of the two columns of reading lines L.

[0104] exist Fig. 10A In the figure, the light receiving element array 12 is opposite to a position deviated from the upper bottom side (short side) of each light receiving lens 111 of the trapezoid. The two ends of each light receiving element array 12 in the X direction overlap each other in the Y direction. However, it is not limited to the configuration in which the two ends of each light receiving element array 12 overlap in the Y direction, and each light receiving element array 12 can also be arranged in a staggered shape within the range of not overlapping in the Y direction. In addition, each light receiving lens 111 has a shape in which the width W1 in the Y direction is smaller than the width W2 in the X direction.

[0105] exist Fig. 10B In the embodiment, each light receiving lens 111 having a rectangular convex portion or concave portion formed at both ends in the X direction is arranged in a row along the X direction. Each light receiving lens 111 is arranged in a manner that the convex portions or concave portions of adjacent light receiving lenses 111 are combined with each other. In addition, each light receiving lens 111 has a shape in which the width W1 in the Y direction is smaller than the width W2 in the X direction.

[0106] Description of Reference Numerals

[0107] 11: light receiving lens array;

[0108] 12: light receiving element array;

[0109] 111: light receiving lens;

[0110] 112: holding plate;

[0111] 113: aperture member;

[0112] 113A: Opening;

[0113] 113B: light shielding part;

[0114] 114: elastic member;

[0115] 120: light receiving lens;

[0116] 130: light receiving lens;

[0117] 300: Optical axis alignment fixture.

Claims

1. A light receiving lens array for imaging light from an object on a reading line extending along a main scanning direction, wherein: The light receiving lens array comprises: a plurality of light receiving lenses arranged in the main scanning direction; and a pair of holding plates, each extending along the main scanning direction and clamping the plurality of light receiving lenses in the sub-scanning direction; Each light receiving lens has a first surface and a second surface that are in contact with the pair of holding plates, respectively.

2. The light receiving lens array according to claim 1, wherein: The first surface and the second surface of each light receiving lens are bonded to the pair of holding plates, respectively.

3. The light receiving lens array according to claim 1, wherein: The plurality of light receiving lenses are arranged with spaces therebetween so that the light receiving lenses adjacent to each other in the main scanning direction do not contact each other.

4. The light receiving lens array according to claim 3, wherein: An elastic member having light-shielding properties and low reflectivity is provided in the space.

5. The light receiving lens array according to claim 1, wherein: The light receiving lens array further includes an aperture member having an opening through which light passing through the light receiving lens passes. The width of the aperture member in the sub-scanning direction matches the distance between the first surface and the second surface.

6. The light receiving lens array according to claim 5, wherein: The aperture member has a truncated cone-shaped opening.

7. The light receiving lens array according to claim 5, wherein: The aperture member is formed such that an opening and a pinhole into which light passing through the opening enters are opposed to each other with a gap therebetween.

8. The light receiving lens array according to claim 6 or 7, wherein: The aperture member is provided with a light shielding portion that closes a portion of the opening to prevent intrusion of stray light.

9. The light receiving lens array according to claim 8, wherein: The optical axis of the light receiving lens is offset in the sub-scanning direction with respect to the reading line.

10. The light receiving lens array according to claim 1, wherein: Each light receiving lens is formed into a trapezoid having the first surface, the second surface having a width smaller than the first surface in the main scanning direction, and a pair of inclined surfaces connecting the first surface and the second surface. The inclined surfaces of the light receiving lenses adjacent to each other in the main scanning direction face each other.

11. The light receiving lens array according to claim 1, wherein: The optical axes of the plurality of light receiving lenses are all located on the same plane and are parallel to each other.

12. An optical line sensor, wherein: The optical line sensor comprises: The light receiving lens array as claimed in claim 1; and A plurality of light receiving elements receive the light transmitted through the plurality of light receiving lenses.

13. An optical line sensor, wherein: The optical line sensor comprises: The light receiving lens array according to claim 11; and a plurality of light receiving elements that receive light that has passed through the plurality of light receiving lenses; The plurality of light receiving elements constitute a plurality of light receiving element arrays extending along the main scanning direction. The plurality of light receiving element arrays are arranged alternately on the two columns of the reading lines. The optical axes of the plurality of light receiving lenses are arranged in the middle of the two rows of the reading lines.

14. A method for manufacturing a light receiving lens array, which is the method for manufacturing a light receiving lens array according to claim 1, wherein: The manufacturing method of the light receiving lens array comprises: a first lens mounting step in which a part of the plurality of light receiving lenses is mounted on one of the pair of holding plates in a manner separated in the main scanning direction; a second lens mounting step in which the remaining portion of the plurality of light receiving lenses is mounted on the other of the pair of holding plates in a manner separated in the main scanning direction; as well as A fixing step, in which the pair of retaining plates are placed face to face, and each light receiving lens is clamped and fixed in the sub-scanning direction by the pair of retaining plates, so that the plurality of light receiving lenses installed on one side of the pair of retaining plates are inserted between the plurality of light receiving lenses installed on the other side of the pair of retaining plates.

15. The method for manufacturing a light receiving lens array according to claim 14, wherein: Each light receiving lens is formed into a trapezoid having the first surface, the second surface having a width smaller than the first surface in the main scanning direction, and a pair of inclined surfaces connecting the first surface and the second surface. In the first lens mounting step, the first surface of a part of the plurality of light receiving lenses is mounted on one of the pair of holding plates. In the second lens mounting step, the first surface of the remaining portion of the plurality of light receiving lenses is mounted on the other of the pair of holding plates.

16. The method for manufacturing a light receiving lens array according to claim 14, wherein: The light receiving lens array further includes an aperture member having an opening through which light passing through the light receiving lens passes. In the first lens mounting step and the second lens mounting step, the plurality of light receiving lenses and the aperture member are mounted on the pair of holding plates using a jig for positioning the plurality of light receiving lenses and the aperture member at predetermined positions.

Images