Rod lens array, rod lens array assembly, sensor unit, reading device, inspection device and recording system

Abstract

To provide a technique which is advantageous in applying a rod lens array to a reduction optical system.SOLUTION: A rod lens array is provided, comprising multiple rod lenses arrayed along an array direction perpendicular to optical axes such that the optical axes are parallel to each other, where some of the multiple rod lenses have end faces of at least either of incident surfaces and exit surfaces coated with a light-shielding material.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a rod lens array, a rod lens array assembly, a sensor unit, a reading device, an inspection device, and a recording system.

Background Art

[0002] Patent Document 1 discloses a lens array that forms an erect and same-magnification image, in which a large number of optical fibers having a refractive index distribution in a direction perpendicular to the optical axis are arranged linearly.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a lens array as shown in Patent Document 1 is applied to a reduction optical system in order to increase the depth of field, the overlapping of images synthesized by a plurality of adjacent lenses is more likely to occur than when applied to an equal-magnification optical system.

[0005] An object of the present invention is to provide a technique advantageous for applying a rod lens array to a reduction optical system.

Means for Solving the Problems

[0006] In view of the above problems, a rod lens array according to an embodiment of the present invention is a rod lens array including a plurality of rod lenses arranged along an arrangement direction perpendicular to the optical axis such that the optical axes are parallel to each other, and a light shielding material is applied so as to cover at least one end surface of the incident surface and the exit surface of some of the plurality of rod lenses. and a plurality of first portions provided with rod lenses coated with the light-shielding material, and a plurality of second portions provided with rod lenses among the plurality of rod lenses that are not coated with the light-shielding material, are alternately arranged, and each of the plurality of second portions is composed of one rod lens that is not coated with the light-shielding material as a rod lens It is characterized by being like this.

Effects of the Invention

[0007] By the above means, a technique advantageous for applying a rod lens array to a reduction optical system is provided.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims, and not all combinations of the features described in the embodiments are essential for the invention. Two or more of the plurality of features described in the embodiments may be arbitrarily combined. Also, the same or similar configurations are given the same reference numerals, and duplicate descriptions are omitted.

[0010] With reference to FIGS. 1(a) to 6(b), a rod lens array according to an embodiment of the present disclosure will be described. FIGS. 1(a) to 1(c) are perspective views showing a configuration example of the rod lens array 100 of the present embodiment. The rod lens array 100 is configured by arranging a plurality of rod lenses 101 linearly (in a row) in the normal direction N of the optical axes L of the plurality of rod lenses 101 so that the optical axes L of the plurality of rod lenses 101 are parallel to each other. In other words, the rod lens array is configured by arranging a plurality of rod lenses 101 along an arrangement direction (a direction perpendicular to the optical axis) different from the optical axis direction so that their optical axes L are parallel to each other. The rod lens 101 includes a non-light-shielded rod lens 101a and a light-shielded rod lens 101b as will be described later. When there is no particular distinction, it is denoted as the rod lens "101", and when distinction is necessary, it is suffixed as the rod lens 101 "a", the rod lens 101 "b". Further, the arrangement direction for arranging the above-described rod lenses 101 does not necessarily have to be perpendicular to the optical axis direction, and it may be different from the optical axis direction. Further, the rod lens 101 constituting the rod lens array 100 of the present embodiment is a lens having a refractive index distribution in the rod lens, with both the incident-side surface and the exit-side surface being flat. Furthermore, this rod lens 101 is a lens that forms an erect image of an object on the image plane (forms an intermediate image).

[0011] The plurality of rod lenses 101 are coupled by a coupling material 102. The rod lens array 100 includes surfaces 151 and 152 that intersect the optical axis direction (optical axis L) of the plurality of rod lenses 101. On surfaces 151 and 152, the end faces of the rod lenses 101 in the optical axis direction are substantially flush with the surrounding coupling material 102. Also, in the configurations shown in FIGS. 1(a) to 1(c), an example in which the plurality of rod lenses 101 are arranged in a row is shown, but it is not limited thereto. Two or more rows of rod lenses 101 may be linearly arranged along the normal direction N (the arrangement direction of the rod lenses 101 different from the optical axis direction). Regardless of the number of rows of rod lenses 101, the rod lens array 100 may have a longitudinal shape in the direction along the normal direction N (arrangement direction) shown in FIGS. 1(a) to 1(c). Hereinafter, the arrangement direction in which the rod lenses 101 are arranged may be described as the "normal direction N" as shown in FIGS. 1(a) to 1(c). However, as described above, the arrangement direction does not necessarily have to be perpendicular to the direction of the optical axis L of the rod lenses 101, and it may be different from the optical axis direction.

[0012] The plurality of rod lenses 101 include rod lenses 101b coated with a light shielding material 103 so as to cover the end faces on the side of surface 151 of the rod lens array 100, as shown in FIGS. 1(a) to 1(c). Also, the plurality of rod lenses 101 include rod lenses 101a whose end faces on the side of surface 151 are not covered by the light shielding material 103, as shown in FIGS. 1(a) to 1(c). The end face of the rod lens 101a on the side of surface 152 is not covered by the light shielding material 103. On the other hand, the end face of the rod lens 101b on the side of surface 152 may not be covered by the light shielding material 103, or the light shielding material 103 may be applied thereto. That is, the light shielding material 103 is applied so as to cover at least one of the end faces of the incident surface and the exit surface of some of the plurality of rod lenses 101b.

[0013] The rod lens 101a exhibits a lens effect, for example, by having a refractive index distribution concentrically in the direction normal to the optical axis L. That is, in the rod lens 101a, light is incident from one end side and an image is formed on the other end side. The rod lens 101b is basically the same rod lens as the rod lens 101a. However, a light-shielding material 103 is applied to cover the end face on the side of the surface 151 of the rod lens 101b. As a result, when light is incident from the side of the surface 151 of the rod lens array 100, at least a part of the incident light is shielded in the rod lens 101b, and it becomes more difficult to form an image on the side of the surface 152 than in the rod lens 101a. Also, when light is incident from the side of the surface 152 of the rod lens array 100, at least a part of the emitted light is shielded in the rod lens 101b, and it becomes more difficult to form an image on the side of the surface 151 than in the rod lens 101a. As the light-shielding material 103, a colored resin such as black can be used. The light-shielding material 103 may cover the entire end portion of the rod lens 101b or may cover a part thereof. By covering at least a part of the rod lens 101b with the light-shielding material 103, the rod lens 101b becomes more difficult to form an image than the rod lens 101a.

[0014] Figs. 2(a) to 2(d) are diagrams showing a configuration example of a rod lens array assembly 300 and a sensor unit 200 using the rod lens array 100. Fig. 2(a) is a perspective view showing a configuration example of the rod lens array assembly 300. As shown in Fig. 2(a), the rod lens array assembly 300 includes the rod lens array 100 shown in Figs. 1(a) to 1(c) and a frame 301 for fixing the positional relationship between the rod lens array 100 and a sensor 212 for receiving light emitted from the rod lens array 100. The frame 301 includes a housing portion 310 for housing the rod lens array 100.

[0015] FIG. 2(b) is a perspective view showing a configuration example of the sensor unit 200, and FIG. 2(c) is an exploded perspective view showing an arrangement example of each component of the sensor unit 200. As shown in FIG. 2(b), the sensor unit 200 includes a rod lens array assembly 300 and a sensor 212 that receives light emitted from the rod lens array 100. The sensor 212 is arranged on a substrate 211 to form a sensor assembly 210, and the positions of the respective sensors 212 can be fixed. Further, a driving element 213 or the like for operating the sensor 212 may be arranged in the sensor assembly 210.

[0016] FIG. 2(d) is a cross-sectional view of the sensor unit 200, and the rod lens array 100 is housed in a housing portion 310 of the frame 301. For example, the frame 301 is provided with an abutting portion 303, and the height of the rod lens 101 in the optical axis direction in the housing portion 310 of the frame 301 can be determined by the abutting portion 303. Further, the frame 301 determines the positional relationship between the rod lens array 100 and the sensor 212 that constitutes the sensor assembly 210. Light is incident from the lower side in FIGS. 2(b) to 2(d), passes through the rod lens array 100, and forms an image on the sensor 212. In FIG. 2(a), although not drawn for simplicity of the figure, a configuration is shown in which the above-described light shielding material 103 is applied to the side of the rod lens 101b where the sensor 212 is arranged. However, the present invention is not limited to this, and the light shielding material 103 may be applied to the surface on the side opposite to the sensor 212 of the rod lens 101b. Further, in the configuration shown in FIG. 2(d), a case is shown in which the abutting portion 303 that determines the height of the rod lens 101 in the optical axis direction in the housing portion 310 of the frame 301 is arranged on the side where the light of the rod lens 101 is incident. However, the present invention is not limited to this. The abutting portion 303 may be arranged on the side of the sensor 212 where the light of the rod lens 101 is emitted, and the height of the rod lens 101 in the optical axis direction in the housing portion 310 of the frame 301 may be determined.

[0017] In the sensor unit 200, for example, when there is a need to increase the depth of field of the rod lens array 100, such as when imaging a subject with unevenness, if the rod lens array 100 in which a plurality of rod lenses 101 are arranged is applied to a reduction optical system, the influence of the overlap of images synthesized by the plurality of adjacent rod lenses 101 will become large. Therefore, in the present embodiment, by preventing some of the plurality of rod lenses 101, i.e., rod lenses 101b, from forming an image or suppressing the formation of an image by the rod lenses 101b, the influence of the overlap of images formed by the plurality of rod lenses 101 is suppressed. As a result, the rod lens array 100 forms a reduced image of the object on the sensor. At this time, the distance from the rod lens array 100 to the sensor 212 can be shorter than the distance from the object imaged on the sensor to the rod lens array 100. For example, the range for capturing an image of the subject may be such that a part of adjacent rod lenses 101a overlap each other. On the other hand, the rod lenses 101a and 101b are arranged so that other rod lenses 101a do not form an image within the range where one rod lens 101a forms an image on the sensor 212. By having the rod lens array 100 configured in this way, it is possible to image the entire subject while suppressing the influence of image overlap. Here, although the imaging magnification of the reduction optical system of the present embodiment is about 0.3 times, it is not limited thereto, and it is desirable that this imaging magnification is 0.05 times or more and 0.9 times or less (more preferably 0.15 times or more and 0.35 times or less).

[0018] For example, as shown in FIGS. 1(a) to 1(c), the rod lens array 100 includes a plurality of portions 112 each having a rod lens 101b with a light-shielding material 103 applied therein, and a plurality of portions 111 each having a rod lens 101a of the plurality of rod lenses 101 without the light-shielding material 103 applied therein. The portions 111 and 112 may be alternately arranged. At this time, each of the plurality of portions 111 may include only one rod lens 101a without the light-shielding material 103 applied thereto as the rod lens 101. In other words, one rod lens 101a without the light-shielding material 103 applied thereto may be arranged in the portion 111 along the normal direction N (arrangement direction). Further, each of the plurality of portions 112 may include a plurality of rod lenses 101b arranged along the normal direction N (arrangement direction) with the light-shielding material 103 applied thereto. In other words, a plurality of rod lenses 101b with the light-shielding material 103 applied thereto may be arranged in the portion 112 along the normal direction N (arrangement direction).

[0019] The number of rod lenses 101b arranged along the normal direction N (the array direction of the rod lenses 101) in the portion 112 may be appropriately designed according to the acceptance angle (aperture angle) of the rod lenses 101, the arrangement pitch of the photoelectric conversion elements arranged on the sensor 212, etc. The number of rod lenses 101b arranged along the normal direction N (array direction) in the portion 112 may be the same in any portion 112, or may be partially different according to the arrangement of the sensor 212, etc. For example, as shown in FIG. 2(b), in order to lengthen the sensor unit 200, a plurality of sensors 212 may be arranged on the substrate 211 of the sensor assembly 210. When there is a joint of the sensor 212 at a position corresponding to the portion 112, the number of rod lenses 101b arranged in the portion 112 can be larger than when there is no joint of the sensor 212 at a position corresponding to the portion 112. Here, the acceptance angle is the maximum angle among the angles formed by the optical axis and the light beam (collection of light rays) that can be imaged by the rod lens among the light beams incident at the position where the light incident surface of the rod lens 101 intersects the optical axis. Also, the acceptance angle is sometimes referred to as the aperture angle. This acceptance angle (aperture angle) is 9 degrees in this embodiment, but it may also be 12 degrees, and preferably it is desirably 3 degrees or more and 21 degrees or less (4.8 degrees or more and 12.3 degrees or less).

[0020] As shown in FIG. 1(a), the surface 151 of the rod lens array 100 may be flat. However, when the surface 151 of the rod lens array 100 is flat, there is a possibility that the light-shielding material 103 may flow into the rod lens 101 that functions as the rod lens 101a. Therefore, on the surface 151 of the rod lens array 100, at least a part of the portion 112 where the rod lens 101b coated with the light-shielding material 103 is arranged may be recessed from the portion 111 where the rod lens 101a not coated with the light-shielding material 103 is arranged. For example, as shown as the recess 104 in FIG. 1(b), on the surface 151 of the rod lens array 100 where the light-shielding material 103 is arranged, the entire portion 112 may be recessed from the portion 111. Also, for example, as shown in FIG. 1(c), on the surface 151 of the rod lens array 100 where the light-shielding material 103 is arranged, a recess 104 that is recessed from the portion 111 may be arranged at least at the end in the normal direction N (arrangement direction) of the portion 112. The recess 104 can be formed, for example, by cutting a part of the surface 151 of the rod lens array 100 using a cutting tool or the like.

[0021] As shown in FIGS. 1(b) and 1(c), recesses 104 are provided on the surface 151 of the rod lens array 100 where the light shielding material 103 is disposed. This can prevent the light shielding material 103 from flowing into the rod lens 101a, and the yield in manufacturing the rod lens array 100 can be higher than that of the configuration shown in FIG. 1(a). Also, by providing the recesses 104, the coating amount when applying the light shielding material 103 may not need to be controlled as precisely as in the configuration shown in FIG. 1(a). Further, by increasing the coating amount when applying the light shielding material 103, it may be possible to more reliably form the light shielding material 103 on the end face of the rod lens 101b. Also, the portion (recess 104) of the portion 112 that is recessed more than the portion 111 may be a blasted surface roughened by blasting or the like. Since the recess 104 is a blasted surface, when applying the light shielding material 103, the light shielding material 103 may easily spread and wet the entire recess 104. As a result, it may be possible to more reliably form the light shielding material 103 on the end face of the rod lens 101b.

[0022] Next, consider the influence of the light shielding material 103 applied on the rod lens 101b on the rod lens 101a. The light shielding material 103 has a thickness on the surface 151 of the rod lens array 100. For example, if the light shielding material 103 exists inside the acceptance angle of the rod lens 101a, the peripheral portion of the image obtained by the rod lens 101a may be blurred. Therefore, it is desirable that the light shielding material 103 is disposed (applied) at a position at an angle equal to or greater than the acceptance angle of the rod lens 101a (outside the acceptance angle) in the optical axis direction from the end face on the side of the surface 151 of the rod lens 101a where the light shielding material 103 is not applied. In other words, it is desirable that any angle formed by the straight line connecting the point on the optical axis of the surface 151 of the rod lens 101a where the light shielding material 103 is not applied and the light shielding material 103 and the optical axis L of the rod lens 101a is greater than the acceptance angle (aperture angle). More preferably, it is even better to be greater than twice (even three times) the acceptance angle. The light shielding material 103 here is a light shielding material located on the object side (light incident side) of the surface 151 of the rod lens 101a.

[0023] When the angle θ shown in FIGS. 1(a) to 1(c) is taken as the acceptance angle of the rod lens 101a, a light shielding material 103 can be disposed between the conical surface formed by the virtual line 131 inclined at an angle θ with respect to the optical axis direction from the end face on the surface 151 side of the rod lens 101a and the surface 151. In other words, when the aforementioned angle θ is taken as the acceptance angle of the rod lens 101a, the light shielding material 103 can be disposed between the side surface of the following cone (cone body) and the surface 151. This cone (cone body) has the center on the surface 151 side of the rod lens 101a (a point on the optical axis) as the apex, and the virtual line 131 inclined at the acceptance angle θ with respect to the optical axis of the rod lens 101a as the side surface with the optical axis of the rod lens 101a as the rotation center. This cone (cone body) has the optical axis of the rod lens 101a as the rotation center and is located on the object side of the surface 151 (the side opposite to the rod lens 101a). In the surface 151 of the rod lens array 100, since the light shielding material 103 is not disposed within the acceptance angle of the rod lens 101a, the influence of the light shielding material 103 on the rod lens 101a can be suppressed. Further, considering the margin, the light shielding material 103 may be disposed at a position at an angle of three times or more the acceptance angle of the rod lens 101a with respect to the optical axis direction (at a position outside three times the acceptance angle) from the end face on the surface 151 side of the rod lens 101a where the light shielding material 103 is not applied. For example, in the recessed portion (recess 104) that is recessed more than the portion 111 in the portion 112 of the surface 151 of the rod lens array 100, the surface of the light shielding material 103 may be closer to the surface 152 of the rod lens array 100 than the surface of the portion 111 (surface 151). As shown in FIGS. 1(b) and 1(c), the recess 104 can be disposed adjacent to the rod lens 101a. Therefore, in the recess 104, the thickness of the light shielding material 103 is made smaller than the step between the portion 111 and the recess 104. Since the surface of the light shielding material 103 disposed in the recess 104 is at a position recessed more than the surface 151 of the portion 111 of the rod lens array 100, the influence of the light shielding material 103 on the rod lens 101a can be suppressed. Here, the inside (outside) of the acceptance angle of the rod lens 101a means the inside (outside) of the cone (the cone on the light incident side of the light incident surface) having the intersection of the light incident surface of the rod lens 101a and the optical axis as the apex and the curved surface having an angle with the optical axis equal to the acceptance angle as the side surface.In other words, the inside (outside) of the acceptance angle of the rod lens 101a means the inside (outside) of a cone that has the intersection of the light incident surface of the rod lens 101a and the optical axis as its apex and twice the acceptance angle as its apex angle and that exists on the light incident side (object side, subject side) of the light incident surface. Note that the center of rotation (axis of rotation) of these cones (conical shapes) coincides with the optical axis of the rod lens.

[0024] The rod lens 101 used in the rod lens array 100 can have an acceptance angle of about 9° as described above. Therefore, the light shielding material 103 may be disposed at a position at an angle of 9° or more with respect to the optical axis direction from the end face on the side of the surface 151 of the rod lens 101a on which the light shielding material 103 is not applied. Further, in consideration of the margin, the light shielding material 103 may be disposed at a position at an angle of 27° or more with respect to the optical axis direction from the end face on the side of the surface 151 of the rod lens 101a on which the light shielding material 103 is not applied.

[0025] Next, the structures of the rod lens array 100 and the frame 301 that constitute the rod lens array assembly 300, and the process of fixing the rod lens array 100 to the frame 301 when manufacturing the rod lens array assembly 300 will be described. FIGS. 3(a) to 5 are diagrams showing various configuration examples when the rod lens array 100 is housed in the housing portion 310 of the frame 301.

[0026] Figs. 3(a) and 3(b) are a top view and an orthographic projection view from the side when the rod lens array 100 without the recess 104, as shown in Fig. 1(a), is accommodated in the accommodation portion 310 of the frame 301. As described above, when the surface 151 of the rod lens array 100 is flat, there is a possibility that the light-shielding material 103 may flow into the rod lens 101 that functions as the rod lens 101a when the light-shielding material 103 is applied. In order to suppress the flow of the light-shielding material 103 into the rod lens 101a, the side wall facing the side surface extending along the normal direction N (the arrangement direction of the rod lenses 101) between the surfaces 151 and 152 of the rod lens array 100 in the accommodation portion 310 includes a portion 312 facing the portion 112 of the rod lens array 100, and a groove 302 may be formed in the portion 312. Fig. 3(a) shows a case where the groove 302 is formed in the central portion of the portion 312 in the normal direction N (the arrangement direction). Fig. 3(b) shows a case where the groove 302 is formed at the end of the portion 312 in the normal direction N (the arrangement direction). By arranging the groove 302, at least a part of the light-shielding material 103 in excess of the required amount can flow into the groove 302, and it is possible to suppress the light-shielding material 103 from flowing into the rod lens 101a. Since the groove 302 is arranged to suppress the flow of the light-shielding material 103 into the rod lens 101a, a groove may not be formed in the portion facing the portion 111 of the side wall of the accommodation portion 310 facing the side surface of the rod lens array 100.

[0027] In the configuration shown in Fig. 3(a), the number of the grooves 302 is small, and high accuracy of the position of the groove 302 in the normal direction N (the arrangement direction) is not required. Also, in the configuration shown in Fig. 3(b), it is possible to suppress the light-shielding material 103 from flowing into the rod lens 101a more effectively than the configuration shown in Fig. 3(a). Also, high accuracy of the position of the groove 302 in the normal direction N (the arrangement direction) is not required.

[0028] FIG. 3(c) is a top view and an orthographic projection view from the side when the rod lens array 100 is housed in the housing portion 310 of the frame 301 in the case where the recess 104 is arranged at the end of the portion 112 of the rod lens array 100 as shown in FIG. 1(c). As shown in FIG. 3(c), the groove 302 may be arranged to face a portion (recess 104) that is recessed more than the portion 111 in the portion 112 of the portion 112 of the rod lens array 100 that faces the portion 312 where the groove 302 is formed. In this case, the depth of the recess 104 and the depth of the groove 302 may be the same, or one may be deeper than the other. FIG. 3(c) shows a case where the groove 302 is deeper than the recess 104. In order to oppose the recess 104 and the groove 302, high precision is required for the formation of the recess 104 in the rod lens array 100 and the formation of the groove 302 in the frame 301. However, the effect of suppressing the light-shielding material 103 from flowing into the rod lens 101a when applying the light-shielding material 103 is greater than that of the configurations shown in FIGS. 3(a) and 3(b).

[0029] FIG. 4(a) shows a case where the recess 104 is formed at the end of the portion 112 of the rod lens array 100, and the groove 302 is formed at the central portion in the normal direction N (arrangement direction) of the portion 312 of the frame 301 that faces the portion 112 of the rod lens array 100. FIG. 4(b) shows a case where the recess 104 is formed in the entire portion 112 of the rod lens array 100, and the groove 302 is formed at the central portion in the normal direction N (arrangement direction) of the portion 312 of the frame 301 that faces the portion 112 of the rod lens array 100. FIG. 4(c) shows a case where the recess 104 is formed in the entire portion 112 of the rod lens array 100, and the groove 302 is formed at the end portion in the normal direction N (arrangement direction) of the portion 312 of the frame 301 that faces the portion 112 of the rod lens array 100. By combining the recess 104 and the groove 302, the effect of suppressing the light-shielding material 103 from flowing into the rod lens 101a is great.

[0030] The concave portion 104 is not limited to being linearly formed in the orthographic projection onto the surface 151. For example, as shown in FIG. 5, in the orthographic projection onto the surface 151, the peripheral edge of the concave portion 104 may be a curve. For example, depending on the shape of a cutting tool or the like, the peripheral edge of the concave portion 104 can have various shapes.

[0031] As shown in FIGS. 3(a) to 5, when the groove 302 is provided, as described above, the light-shielding material 103 flows into the groove 302. In this case, the light-shielding material 103 easily enters between the side surface of the rod lens array 100 and the side surface of the frame 301 through the groove 302 due to capillary action or the like. Therefore, the light-shielding material 103 may function as a coupling member that couples the rod lens array 100 and the frame 301. That is, the light-shielding material 103 may be an adhesive colored black or the like. In this case, the rod lens array 100 is housed in the housing portion 310 of the frame 301, and by applying the light-shielding material 103 that functions as a coupling member, the rod lens array assembly 300 is manufactured. By the light-shielding material 103 functioning as a coupling member, an increase in the number of steps in manufacturing the rod lens array assembly 300 is suppressed.

[0032] When the light-shielding material 103 functions as a coupling member or the like, stress may be generated between the rod lens array 100 and the frame 301 due to environmental changes such as the temperature during use. As shown in FIGS. 3(b), 3(c), and 4(c), when the groove 302 is arranged near the rod lens 101a, this stress may affect the rod lens 101a. In this case, as shown in FIGS. 3(a), 4(a), and 4(b), arranging the groove 302 at the center of the side wall of the frame 301 can suppress the influence of the stress generated between the rod lens array 100 and the frame 301. On the other hand, the configurations shown in FIGS. 3(b), 3(c), and 4(c) can more reliably suppress the light-shielding material 103 from flowing into the rod lens 101a.

[0033] Also, when the light-shielding material 103 functions as a coupling member, the influence of stress may become significant due to, for example, the elongation in the normal direction N (array direction) of the rod lens array 100 and the frame 301. Therefore, the groove 302 may be made shallower continuously or stepwise from the central portion toward the end portion in the normal direction N (array direction) of the frame 301. That is, at the central portion in the normal direction N (array direction) of the rod lens array assembly 300, the rod lens array 100 and the frame 301 may be firmly fixed, and the coupling strength between the rod lens array 100 and the frame 301 may be weakened toward the end portion.

[0034] In this way, the light-shielding material 103 is applied so that some of the plurality of rod lenses (rod lens 101b) among the plurality of rod lenses 101 are difficult to form an image. As a result, it is possible to suppress a decrease in image quality caused by the overlap of images synthesized by a plurality of adjacent rod lenses, apply the rod lens array 100 to a reduction optical system, and increase the depth of field.

[0035] In the sensor unit 200, it is conceivable to arrange a plurality of rod lenses at a predetermined interval without using the rod lens array 100 including the rod lenses 101a and 101b. However, in order to align the optical axes of rod lenses of about φ1.0 mm at a predetermined interval according to the positions of photoelectric conversion elements and the like arranged in the sensor 212, high accuracy is required, which may also cause an increase in cost. On the other hand, in the present embodiment, since the rod lens array generally used in the sensor unit 200 and the like is processed, the accuracy when assembling the rod lens array 100 into the sensor unit 200 and the like can be equivalent to that when manufacturing a normal sensor unit 200. Further, the rod lens array 100 can be manufactured simply by applying the light-shielding material 103 to a general-purpose rod lens array. Further, since the light-shielding material 103 can also be used as a coupling member between the rod lens array 100 and the frame 301, the influence on the cost can also be suppressed.

[0036] In addition, in order to block light from some of the rod lenses 101, it is conceivable to dispose a light-blocking member, which is a separate member from the rod lens array, on some of the plurality of rod lenses 101 arranged in a general-purpose rod lens array. For example, as the light-blocking member, it is conceivable to dispose a metal plate or a resin plate having a part thereof opened so as to cover the rod lens array. However, due to differences in structure and material, etc., the light-blocking member is likely to have a linear expansion rate different from that of the rod lens array. Therefore, it is difficult to align the light-blocking member with respect to each rod lens 101 of the general-purpose rod lens array in response to environmental changes such as temperature and the elongation of the sensor unit 200. On the other hand, in the present embodiment, since the light-blocking material 103 is directly applied to the surface 151 of the rod lens array 100, it is possible to cope with environmental changes and the elongation of the sensor unit 200.

[0037] Next, as an application example of the rod lens array 100 of the present embodiment, a reading device, an inspection device, and a recording system including a sensor unit 200 in which the rod lens array 100 is incorporated will be described. FIG. 6(a) is a diagram for explaining a reading device 400 including a sensor unit 200 in which the rod lens array 100 is incorporated, and an inspection device 500 including the reading device 400. FIG. 6(b) is a diagram for explaining a reading device 400 including a sensor unit 200 in which the rod lens array 100 is incorporated, and a recording system 510 including the reading device 400.

[0038] As shown in FIGS. 6(a) and 6(b), the reading device 400 includes an illumination device 401 and an image sensor 402 for acquiring image information of an illuminated object 411 (subject) illuminated by the illumination device 401. The image sensor 402 is provided with the sensor unit 200 in which the above-described rod lens array 100 is incorporated.

[0039] When the illuminand 411 has a difference in size (height) as shown in FIGS. 6(a) and 6(b), a deep depth of field is required for imaging. Therefore, by providing the rod lens array 100 with the above-described configuration, the reading device 400 including the sensor unit 200 in which the rod lens array 100 is incorporated can focus on illuminands 411 having different heights.

[0040] The reading device 400 that can be focused on illuminands 411 having different sizes can be applied to, for example, an inspection device 500 as shown in FIG. 6(a). The inspection device 500 may include the reading device 400 and a determiner 501 that determines the quality of the illuminand 411 using the image information acquired by the reading device 400. Further, the inspection device 500 may include a transport device 502 for transporting the illuminand 411 as shown in FIG. 6(a). The inspection device 500 may be an inspection device that includes, for example, a sensor unit 200 (line sensor unit) including a linear rod lens array 100 and a sensor assembly 210 and inspects the illuminand 411 moving on the transport device 502. The reading device 400 that can be focused on illuminands 411 having different sizes can improve the accuracy of inspection in the inspection device 500.

[0041] In addition, a reading device 400 that can focus on different-sized illuminated objects 411 can be applied to, for example, a recording system 510 as shown in FIG. 6(b). The recording system 510 includes a reading device 400 and a recording device 511 that performs recording on a recording medium based on the image information acquired by the reading device 400. The recording system 510 includes a copying machine, a printer, a data recording device that records data on a hard disk or a memory, and the like. FIG. 6(b) shows an example of recording on a paper medium such as a copying machine or a printer in the recording system 510. The recording system 510 may perform imaging while moving the illuminated object 411 as in the above-described inspection device 500, or may image the illuminated object 411 by moving the reading device 400. Even when the illuminated object 411 has irregularities as shown in FIG. 6(b), the recording system 510 including the reading device 400 including the sensor unit 200 incorporating the rod lens array 100 can record an in-focus image on the surface of the illuminated object 411.

[0042] The recording device 511 can record an image including characters on a recording medium 513 (e.g., paper) by any method such as an inkjet method or an electrophotographic method. In this case, the recording system 510 may include a transport device 512. As the transport device 512, a transport roller that transports the recording medium from upstream to downstream can be used. In one embodiment, the recording system 510 can perform copying processing. In this case, the recording device 511 records the image information read by the reading device 400 on the recording medium as an image. Also, in one embodiment, the recording system 510 can perform feedback control. For example, the reading device 400 can read the image information with respect to the recording medium 513 after recording is performed by the recording device 511 and transmit it to the recording device 511 as read data. Based on this read data, the recording device 511 can confirm the recording state on the recording medium and control the recording parameters for the next recording.

[0043] Also, the recording system 510 is not limited to the device that records on a recording medium 513 such as paper as described above. The recording device 511 may record the image information and the like read by the reading device 400 as electronic data on a recording medium such as a hard disk or a memory. In this case, the recording device 511 may include a recording medium such as a hard disk or a memory. In this case, the conveying device 512 may not be provided in the recording system 510.

[0044] The invention is not limited to the above-described embodiments, and various modifications and changes are possible within the scope of the gist of the invention.

Explanation of Reference Numerals

[0045] 100: Rod lens array, 101a, 101b: Rod lens, 102: Bonding material, 103: Light shielding material, 151, 152: Surfaces

Claims

1. A rod lens array including a plurality of rod lenses arranged along an arrangement direction perpendicular to the optical axes such that the optical axes are parallel to each other, wherein a light-shielding material is applied so as to cover at least one end surface of the incident surface and the exit surface of some of the plurality of rod lenses, a plurality of first portions in which the rod lenses coated with the light-shielding material are arranged and a plurality of second portions in which the rod lenses not coated with the light-shielding material among the plurality of rod lenses are arranged are alternately arranged, and each of the plurality of second portions is composed of one rod lens not coated with the light-shielding material as the rod lens. The rod lens array is characterized by this.

2. The light-shielding material is arranged at a position at an angle of three times or more the acceptance angle of the rod lens in the direction of the optical axis from the end surface of the rod lens not coated with the light-shielding material among the plurality of rod lenses. The rod lens array according to claim 1, characterized by this.

3. The light-shielding material is arranged at a position at an angle of 27° or more with respect to the direction of the optical axis from the end surface of the rod lens not coated with the light-shielding material among the plurality of rod lenses. The rod lens array according to claim 1, characterized by this.

4. Each of the plurality of first portions is arranged along the arrangement direction and includes a plurality of rod lenses coated with the light-shielding material. The rod lens array according to any one of claims 1 to 3, characterized by this.

5. In the surface of the rod lens array where the light-shielding material is arranged, a recess recessed more than the second portion is arranged at least at an end portion in the arrangement direction of the first portion. The rod lens array according to any one of claims 1 to 4, characterized by this.

6. In the recess, the thickness of the light-shielding material is smaller than the step difference between the second portion and the recess. The rod lens array according to claim 5, characterized by this.

7. A rod lens array according to any one of claims 1 to 6, and a frame for fixing the positional relationship between the rod lens array and a sensor for receiving light emitted from the rod lens array. The rod lens array assembly is characterized by including these.

8. The frame includes a housing portion for housing the rod lens array. Of the accommodating portion, a side wall facing a side surface extending along the arrangement direction of the rod lens array includes a plurality of third portions facing the plurality of first portions of the rod lens array. The rod lens array assembly according to claim 7, wherein grooves are formed in the plurality of third portions.

9. The rod lens array assembly according to claim 8, wherein the grooves are formed at least at ends in the arrangement direction among the third portions.

10. The rod lens array according to claim 5 or 6, a frame for fixing a positional relationship between the rod lens array and a sensor for receiving light emitted from the rod lens array, A rod lens array assembly including: the frame includes an accommodating portion for accommodating the rod lens array, Of the accommodating portion, a side wall facing a side surface extending along the arrangement direction of the rod lens array includes a plurality of third portions facing the plurality of first portions of the rod lens array. grooves are formed in the plurality of third portions, The rod lens array assembly, wherein the grooves face recesses among the plurality of first portions facing the plurality of third portions in which the grooves are formed.

11. The rod lens array assembly according to any one of claims 8 to 10, wherein no grooves are formed in a fourth portion of the side wall facing the second portion.

12. The rod lens array assembly according to any one of claims 7 to 11, wherein the light shielding material functions as a coupling member for coupling the rod lens array and the frame.

13. The rod lens array assembly according to any one of claims 7 to 12, a sensor for receiving light emitted from the rod lens array, A sensor unit, characterized by including:

14. The sensor unit according to claim 13, wherein the rod lens array forms a reduced image of an object image on the sensor.

15. The sensor unit according to claim 13 or 14, wherein a distance from the rod lens array to the sensor is shorter than a distance from an object imaged on the sensor to the rod lens array.

16. An illumination device An image sensor for acquiring image information of an illuminated object illuminated by the illumination device, A reading device including: The reading device, wherein the image sensor includes the sensor unit according to any one of claims 13 to 15.

17. The reading device according to claim 16, A determiner that determines the quality of the illuminated object using the image information acquired by the reading device, An inspection device characterized by including:

18. The reading device according to claim 16, A recording device that records the image information acquired by the reading device on a recording medium, A recording system characterized by including:

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