Reading device, inspection device, reading system, and method for manufacturing a reading device

Abstract

To provide a technique advantageous in improving the image quality of a reading device.SOLUTION: A reading device comprises a sensor that includes a plurality of pixels arranged along a main scanning direction, and a plurality of lens blocks. The plurality of lens blocks each include a plurality of rod lenses arranged along a direction intersecting an optical axis. The plurality of rod lenses included in each of the plurality of lens blocks include a use lens forming an image on the sensor and a non-use lens not forming an image on the sensor. The use lenses of the plurality of lens blocks are arranged along the main scanning direction. The plurality of lens blocks are arranged separate from each other along the main scanning direction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a reading device, an inspection device, a reading system, and a method for manufacturing a reading device.

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. When such a lens array that forms an erect and same-magnification image is used, images of two adjacent lenses overlap on the sensor. However, since the same image is formed at the same position on the sensor, no problem occurs even if they overlap.

Prior Art Documents

Patent Documents

[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 reading device, the overlap of images synthesized by a plurality of adjacent lenses causes the depth of field to become shallow, which may lead to a deterioration in the image quality of the obtained image. In particular, 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 positions of images formed on the sensor by two adjacent lenses shift from each other (the images of the same position on the subject are formed at different positions on the sensor). As a result, different images on the sensor overlap, and a clear image of the subject cannot be formed on the sensor.

[0005] An object of the present invention is to provide a technique advantageous for improving the image quality of a reading device.

Means for Solving the Problems

[0006] In view of the above problems, a reading device according to an embodiment of the present invention includes a sensor including a plurality of pixels arranged along a main scanning direction, and a plurality of lens blocks, wherein each of the plurality of lens blocks includes a plurality of rod lenses arranged along a direction intersecting the optical axis, and the plurality of rod lenses included in each of the plurality of lens blocks include a used lens that forms an image on the sensor and an unused lens that does not form an image on the sensor, and the used lenses of each of the plurality of lens blocks are arranged along the main scanning direction, and the plurality of lens blocks are arranged spaced apart from each other along the main scanning direction.

Advantages of the Invention

[0007] By the above means, a technique advantageous for improving the image quality of the reading device is provided.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments 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 denoted by the same reference numerals, and redundant descriptions are omitted.

[0010] Referring to FIGS. 1(a), 1(b) to FIGS. 5(a), 5(b), a reading device according to an embodiment of the present disclosure will be described. FIG. 1(a) is a perspective view showing a configuration example of the reading device 100 of the present embodiment, FIG. 1(b) is a plan view of the lens block 101 used in the reading device 100, and FIG. 2 is a plan view and a cross-sectional view of the reading device 100.

[0011] The reading device 100 includes a sensor 102 including a plurality of pixels arranged along the main scanning direction 151, and a plurality of lens blocks 101. Each of the plurality of lens blocks 101 includes a plurality of rod lenses 110 arranged along a direction intersecting the optical axis. The plurality of rod lenses 110 included in each of the plurality of lens blocks 101 include a used lens 111 that forms an image on the sensor 102 and an unused lens 112 that does not form an image on the sensor 102. The used lens 111 can be said to be a lens that guides light to the sensor 102. Also, the unused lens 112 can be said to be a lens that does not guide light to the sensor 102. The used lenses 111 of each of the plurality of lens blocks 101 are arranged along the main scanning direction 151 (specifically, arranged on a virtual line indicated by reference numeral 152). In other words, they are arranged in a single straight line (on a virtual line) parallel to the main scanning direction. Also, the plurality of lens blocks 101 are arranged at intervals from each other along the main scanning direction 151. Note that the state in which the plurality of lens blocks 101 are spaced apart from each other along the main scanning direction 151 means a state in which the lens blocks 101 are spaced apart on a straight line parallel to the main scanning direction 151. That is, even if the lens blocks 101 adjacent to each other in the main scanning direction 151 overlap when viewed from the sub-scanning direction perpendicular to the main scanning direction 151, they only need to be spaced apart in the main scanning direction 151.

[0012] When a rod lens array including a plurality of rod lenses is arranged such that the rod lenses are along the main scanning direction, a part of the emitted light of adjacent rod lenses overlaps on the sensor 102. The overlap of the images synthesized by the plurality of rod lenses can cause a deterioration in image quality.

[0013] Therefore, in the present embodiment, as shown in FIGS. 1(a) to 2, the use lenses 111 that form images on the sensor 102 are arranged at intervals along the main scanning direction 151. Thereby, overlapping of images synthesized by a plurality of adjacent rod lenses is suppressed. FIGS. 1(a) and 2 show an image circle 121 formed by the use lens 111. The area of the image circle 121 is defined by the focal length f of the use lens 111, the distance from the light emitting surface of the use lens 111 to the sensor 102, and the aperture angle of the use lens 111. The aperture angle is the maximum value of the angle formed by the optical axis and a light ray that can enter one end of the optical axis of the use lens 111, which is a refractive index distribution type lens.

[0014] For example, when a rod lens array is applied to a reduction optical system to increase the depth of field, the positions of images formed on the sensor by two adjacent lenses are shifted from each other (the images of the same position on the subject are formed at different positions on the sensor). As a result, different images on the sensor are superimposed on each other, and a clear image of the subject cannot be formed on the sensor. On the other hand, in the reading device 100 of the present embodiment, the image circles 121 formed by the respective use lenses 111 are arranged at intervals from each other. That is, even when the use lens 111 is applied to a reduction optical system that reduces and forms an image of a subject on the sensor 102, it is possible to realize a reading device 100 with a deep depth of field and suppressed deterioration of image quality. The magnification M by the reduction optical system here satisfies 0.05 ≦ M ≦ 0.80 ··· (1) It is desirable that the relationship is satisfied. If it is below the lower limit of formula (1), the obtained image becomes rough, which is not preferable. The lower limit of this formula (1) may be 0.10 or more, or further 0.18 or more. On the other hand, when the upper limit of formula (10) is exceeded, the depth of field becomes shallow. Therefore, the upper limit of formula (1) may be more preferably 0.70 or less, or 0.40 or less in consideration of the depth of the depth of field.

[0015] In the configuration shown in FIGS. 1(a) to 2, a plurality of rod lenses 110 included in each of the plurality of lens blocks 101 are arranged in a direction (e.g., the sub-scanning direction) intersecting the main scanning direction 151. Also, one of the plurality of rod lenses 110 included in each of the plurality of lens blocks 101 functions as the used lens 111. On the other hand, the rod lenses 110 other than the used lens 111 among the plurality of rod lenses 110 included in each of the plurality of lens blocks 101 function as unused lenses 112.

[0016] The unused lens 112 may be made such that it does not form an image on the sensor 102 or makes it difficult to form an image by performing appropriate processing on the rod lens 110. For example, the unused lens 112 can be formed by shielding at least a part of the light-emitting surface or the light-incident surface of the rod lens 110. Also, for example, a light-shielding material may be applied to the light-emitting surface or the light-incident surface of the rod lens 110 that becomes the unused lens 112, or a light-shielding tape may be attached. Further, the unused lens 112 may be partially defective with respect to the used lens 111. For example, the light-incident surface of the rod lens 110 that becomes the unused lens 112 may be roughened into a convex-concave shape by polishing or the like. The light incident on the rod lens 110 is scattered at the light-incident surface and heads toward the side wall of the rod lens 110 or the like, making it difficult to form an image on the sensor 102. Also, the light-emitting surface or the light-incident surface of the rod lens 110 may be inclined from the normal direction of the optical axis. When the light-emitting surface is inclined, the light-emitting surface of the rod lens 110 may be inclined so that the emitted light does not head toward the sensor 102. Also, when the light-incident surface of the rod lens 110 is inclined, the incident light is absorbed by the side wall of the rod lens 110 or the like, making it difficult to form an image on the sensor 102. Further, the space between the light-incident surface and the light-emitting surface of the rod lens 110 that becomes the unused lens 112 may not be continuous.

[0017] As shown in FIG. 1(b), each lens block 101 may be formed by dividing a rod lens array including a plurality of rod lenses 110 arranged along a direction intersecting the optical axis. For example, a part of the rod lenses 110 arranged in the rod lens array is subjected to the above-described processing that makes imaging difficult. Next, according to the position of the unprocessed usable lens 111, the rod lens array is cut at an appropriate position, and the plurality of formed lens blocks 101 are arranged at corresponding positions of the sensor 102, whereby the reading device 100 can be manufactured. For example, even when the accuracy of the processing that makes it difficult for the rod lens 110 to form an image is low, the lens block 101 can be obtained by picking up the rod lens that functions as the usable lens 111 from the processed rod lens array and cutting it to an appropriate length. The lens block 101 divided from the rod lens array has a configuration in which the rod lenses 110 are arranged in the integrally structured coupling member 115 as shown in FIG. 1(b). The coupling member 115 couples the plurality of rod lenses 110 in each of the lens blocks 101. The coupling member 115 can be integrally formed of, for example, a resin of a material different from that of the rod lenses 110. The coupling member 115 may be colored in an appropriate color such as black.

[0018] Here, when incorporated into the reading device 100 as shown in FIG. 1(a) among the lens blocks 101, the surface on which light is incident on the rod lens 110 arranged in the lens block 101 is called the light incident surface. Further, among the lens blocks 101, the surface that is arranged on the side of the sensor 102 and from which light is emitted from the usable lens 111 to the sensor 102 is called the light emission surface. At this time, the surface between the light incident surface and the light emission surface among the lens blocks 101 is called the side wall. The side wall of the lens block 101 is preferably parallel to the surface constituted by the optical axis of the rod lens 110 and the two axes in the direction in which the rod lenses 110 are arranged. Further, the side wall of the lens block 101 and the light incident surface are preferably perpendicular to each other. Similarly, the side wall of the lens block 101 and the light emission surface are preferably perpendicular to each other.

[0019] In the reading device 100, it is conceivable to arrange a plurality of rod lenses at a predetermined interval without using the lens block 101. However, in order to arrange rod lenses with a diameter of about φ1.0 mm with their optical axes aligned at a predetermined interval, high precision is required, which may also cause an increase in cost. On the other hand, in the present embodiment, the lens block 101 can be formed by dividing the rod lens array. Further, the reading device 100 includes a frame 201 provided with a housing portion 202 for housing a plurality of lens blocks 101. Each lens block 101 is fixed to the frame 201 that fixes the positions of the plurality of lens blocks 101 with respect to the sensor 102. By these steps, the used lens 111 arranged in the lens block 101 can be easily and highly accurately arranged at a predetermined position.

[0020] Also, the used lens 111 and the unused lens 112 arranged in the lens block 101 are rod lenses 110 of the same material. Therefore, compared with the case where a plurality of rod lenses are arranged at a predetermined interval, even when there are environmental changes such as temperature, it is difficult for effects such as the rod lenses tilting in an unintended direction due to differences in the coefficient of thermal expansion to occur.

[0021] For example, as shown in FIG. 2, a plurality of accommodating portions 202 are provided in the frame 201, and each of the plurality of accommodating portions 202 may be arranged with one of the plurality of lens blocks 101 one by one. In other words, the accommodating portions 202 may be arranged independently for each of the plurality of lens blocks 101. By inserting the lens block 101 into the accommodating portion 202, the alignment of the used lens 111 can be easily performed. Further, the accommodating portion 202 may be provided with abutting portions 203 for determining the positions of the plurality of lens blocks 101 in the optical axis direction. By abutting the lens block 101 against the abutting portion 203, the distance between the used lens 111 and the sensor 102 can be easily adjusted. That is, in the orthographic projection in the optical axis direction of the rod lens 110, at least a part of the coupling member 115 may be arranged in a region overlapping the abutting portion 203. In the configuration shown in FIG. 2, an example in which the abutting portion 203 is arranged between the lens block 101 and the sensor 102 is shown, but the present invention is not limited thereto. Depending on the configuration of the reading device 100, for example, the abutting portion 203 may be arranged on the side opposite to the sensor 102 of the lens block 101 (the subject side). Further, the abutting portion 203 may extend beyond the coupling member 115 to the position where the unused lens 112 is arranged. That is, in the orthographic projection in the optical axis direction of the rod lens 110, at least a part of the unused lens 112 may be arranged in a region overlapping the abutting portion 203.

[0022] In the configurations shown in FIGS. 1(a) and 2, the unused lens 112 may not be subjected to the above-described processing that makes imaging difficult even if such processing is not performed. For example, when the image circle of the unused lens 112 adjacent to the used lens 111 is not arranged on the sensor 102, the unused lens 112 may not be subjected to processing for light shielding or the like. Also, for example, at the end of the image circle, the image becomes dark and aberration effects and the like may occur. Therefore, even if the image circle of the unused lens 112 overlaps the image circle 121 of the used lens 111, it is conceivable to generate an image without using the signal output from the overlapping region. Further, for example, as shown in FIG. 1(a), it is conceivable that the image circle 121 of the used lens 111 is larger than the sub-scanning direction of the sensor 102. In this case, even if the image circle of the unused lens 112 overlaps the image circle 121 of the used lens 111, it is conceivable that the overlapping region is not on the sensor 102. Even in such a case, without subjecting the rod lens 110 to the above-described processing that makes imaging difficult, the rod lens array is cut to an appropriate size and accommodated as the lens block 101 in the accommodating portion 202 of the frame 201. By these steps, the optical system of the reading device 100 can be manufactured with high accuracy.

[0023] FIGS. 3 and 4 are diagrams showing a modified example of the above-described reading device 100. The plurality of rod lenses 110 included in each of the plurality of lens blocks 101 of the reading device 100 may be arranged along the main scanning direction 151. When having this configuration, as the unused lens 112, a lens subjected to the above-described processing that makes imaging difficult with respect to the rod lens 110 can be used.

[0024] In the configuration shown in FIGS. 3 and 4, the number of the used lenses 111 arranged in one lens block 101 is not limited to one. Depending on the size of the image circle 121 of the used lens 111 and the size of the main scanning direction 151 of the lens block 101, two or more rod lenses 110 may function as the used lens 111. In this case, the image circles 121 of two adjacent used lenses 111 may not overlap. Further, when the ends of the image circles 121 of two adjacent used lenses 111 overlap, an image may be generated without using the signal output from the overlapping region of the image circles 121 of the sensor 102.

[0025] As shown in FIG. 4, in the orthographic projection in the optical axis direction of the rod lens 110, at least a part of the coupling member 115 is arranged in a region overlapping the abutting portion 203, whereby the position of the lens block 101 in the optical axis direction can be determined. Further, as shown in FIG. 4, the abutting portion 203 may extend beyond the coupling member 115 to the position where the unused lens 112 is arranged. That is, in the orthographic projection in the optical axis direction of the rod lens 110, at least a part of the unused lens 112 may be arranged in a region overlapping the abutting portion 203. The unused lens 112 does not need to form an image on the sensor 102. Therefore, the light incident surface or the light exit surface of the unused lens 112 and the abutting portion 203 may overlap. When this configuration is used, it becomes possible to make the abutting portion 203 larger. That is, the stability when the lens block 101 is accommodated in the accommodating portion 202 of the frame 201 is improved, and it becomes possible to more easily enhance the accuracy of the position and arrangement of the used lens 111 in the optical axis direction. Also in the configuration shown in FIG. 2, an abutting portion 203 may be provided at an end portion in a direction intersecting the main scanning direction 151 (reference numeral 152) of the accommodating portion 202 so as to overlap the unused lens 112 in the orthographic projection in the optical axis direction of the rod lens 110.

[0026] In the configurations shown in FIGS. 1(a) to 4, the number of rod lenses 110 arranged in the lens block 101 is five, but it is not limited to this. The number of rod lenses 110 may be four or less, or six or more. However, from the viewpoints of the number of steps for cutting the rod lens array and the size that is easy to handle, the number of rod lenses 110 arranged in the lens block 101 may be three or more, and further, five or more. Also, in the configurations shown in FIGS. 1(a) and 2, when the number of rod lenses 110 arranged in the lens block 101 increases, the size in the sub-scanning direction intersecting the main scanning direction 151 of the lens block 101 increases, and the number of unused lenses 112 relatively increases. Also, in the configurations shown in FIGS. 3 and 4, when the number of rod lenses 110 arranged in the lens block 101 increases, the number of unused lenses 112 may relatively increase. That is, since an appropriate number of lens blocks 101 can be obtained from the rod lens array and it is also advantageous in terms of cost, the number of rod lenses 110 arranged in the lens block 101 may be 20 or less, and further, 10 or less.

[0027] As described above, in this embodiment, an image reading apparatus 100 is obtained that suppresses deterioration in image quality caused by overlapping of images synthesized by a plurality of adjacent lenses when using a rod lens array. Also, compared with the case where a plurality of rod lenses are arranged at a predetermined interval, the used lenses 111 can be arranged with high accuracy. Further, an image reading apparatus 100 that is also resistant to environmental changes can be realized.

[0028] Next, as an application example of the image reading apparatus 100 of this embodiment, an inspection apparatus and an image reading system in which the image reading apparatus 100 is incorporated will be described. FIG. 5(a) is a diagram for explaining an inspection apparatus 500 in which the image reading apparatus 100 is incorporated. FIG. 5(b) is a diagram for explaining an image reading system 510 in which the image reading apparatus 100 is incorporated.

[0029] As shown in FIGS. 5(a) and 5(b), the reading device 100 may acquire image information of a subject 550 (illuminated object) illuminated by an illumination device 131. That is, the reading device 100 may further include an illumination device 131 for illuminating the subject 550.

[0030] When the subject 550 has a difference in size (height) as shown in FIGS. 5(a) and 5(b), a deep depth of field is required for imaging. Therefore, the reading device 100 including an optical system that can be applied to a reduction optical system with a deep depth of field, in which the use lenses 111 that form images on the sensor 102 are arranged apart from each other along the main scanning direction 151, can focus on the subjects 550 with different heights.

[0031] The reading device 100 that can focus on subjects 550 with different sizes can be applied to, for example, an inspection device 500 as shown in FIG. 5(a). The inspection device 500 may include the reading device 100 and an inspection unit 501 that inspects the state of the subject 550 using the image information acquired by the reading device 100. Here, the state may be a pass / fail state of the subject 550 with respect to a determination criterion provided in advance for a specific item (for example, size, color tone, etc.), the state of the image quality of a printed matter, or the color development state of a printed matter. For example, the inspection unit 501 may inspect whether the subject 550 is in a predetermined state or may perform an inspection for classification according to the size, color, etc. of the subject 550. Further, the inspection device 500 may include a transport device 502 for transporting the subject 550 as shown in FIG. 5(a). The inspection device 500 may be, for example, an inspection device including a plurality of lens blocks 101 and a line sensor 102 (for example, a line sensor extending in a direction intersecting the plane of FIG. 5(a)) that inspects the subject 550 moving on the transport device 502. The accuracy of inspection in the inspection device 500 can be improved by the reading device 100 that can focus on subjects 550 with different sizes.

[0032] In addition, the reading device 100 that can focus on subjects 550 of different sizes can be applied to a reading system 510, for example, as shown in FIG. 5(b). The reading system 510 includes the reading device 100 and a storage device 511 that stores information in a storage medium based on the image information acquired by the reading device 100. The reading system 510 includes a copying machine, a printer, a data storage device that stores data in a hard disk or a memory, and the like. The reading system 510 may perform imaging while moving the subject 550 like the inspection device 500 described above, or may image the subject 550 by moving the reading device 100. Even when the subject 550 has irregularities as shown in FIG. 5(b), the reading system 510 including the reading device 100 having an optical system in which the used lenses 111 that form images on the sensor 102 are arranged at intervals along the main scanning direction 151 and that is applicable to a reduction optical system with a deep depth of field can store an image in focus on the surface of the subject 550.

[0033] The storage device 511 may store image information and the like read by the reading device 100 as electronic data in a storage medium such as a hard disk or a memory. In this case, the storage device 511 may include a storage medium such as a hard disk or a memory. Further, the storage device 511 may include a communication device that transfers image information and the like read by the reading device 100 to a storage medium such as a storage device on the cloud arranged outside the storage device 511.

[0034] 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

[0035] 100: Reading device, 101: Lens block, 102: Sensor, 110: Rod lens, 111: Used lens, 112: Unused lens, 151: Scanning direction

Claims

1. A reading device comprising a sensor including a plurality of pixels arranged along a main scanning direction, and a plurality of lens blocks, wherein each of the plurality of lens blocks includes a plurality of rod lenses arranged along a direction intersecting the optical axis, the plurality of rod lenses included in each of the plurality of lens blocks include a used lens that forms an image on the sensor and an unused lens that does not form an image on the sensor, the used lenses of each of the plurality of lens blocks are arranged along the main scanning direction, and the plurality of lens blocks are arranged spaced apart from each other along the main scanning direction.

2. A reading device comprising a sensor including a plurality of pixels arranged along a main scanning direction, and a plurality of lens blocks, wherein each of the plurality of lens blocks includes a plurality of rod lenses arranged along a direction intersecting the optical axis, the plurality of rod lenses included in each of the plurality of lens blocks include a used lens that guides light to the sensor and an unused lens that does not guide light to the sensor, the used lenses of each of the plurality of lens blocks are arranged along the main scanning direction, and the plurality of lens blocks are arranged spaced apart from each other along the main scanning direction.

3. The reading device according to claim 1 or 2, wherein one of the plurality of rod lenses included in each of the plurality of lens blocks functions as the used lens.

4. The reading device according to any one of claims 1 to 3, wherein the plurality of rod lenses included in each of the plurality of lens blocks are arranged in a direction intersecting the main scanning direction.

5. The reading device according to any one of claims 1 to 3, wherein the plurality of rod lenses included in each of the plurality of lens blocks are arranged in the main scanning direction.

6. The reading device according to any one of claims 1 to 5, wherein the number of the plurality of rod lenses included in each of the plurality of lens blocks is 3 or more and 20 or less.

7. The reading device according to any one of claims 1 to 6, wherein the light incident surface or the light exit surface of the unused lens is shielded.

8. ​ ​ The reading device according to any one of claims 1 to 7, wherein the unused lens is partially defective with respect to the used lens.

9. The reading device according to any one of claims 1 to 8, wherein the plurality of rod lenses are refractive index distribution type lenses.

10. A frame provided with a housing portion for housing the plurality of lens blocks, The reading device according to any one of claims 1 to 9, wherein the frame fixes the positions of the plurality of lens blocks with respect to the sensor.

11. A plurality of the housing portions are provided in the frame, The reading device according to claim 10, wherein the plurality of lens blocks are respectively arranged one by one in the plurality of housing portions.

12. A butting portion for determining the position of each of the plurality of lens blocks in the optical axis direction is arranged in the housing portion, The reading device according to claim 10 or 11, wherein in the orthographic projection in the optical axis direction, at least a part of the unused lenses is arranged in a region overlapping the butting portion.

13. A butting portion for determining the position of each of the plurality of lens blocks in the optical axis direction is arranged in the housing portion, Each of the plurality of lens blocks includes a coupling member for coupling the plurality of rod lenses, The reading device according to any one of claims 10 to 12, wherein in the orthographic projection in the optical axis direction, at least a part of the coupling members is arranged in a region overlapping the butting portion.

14. The reading device according to any one of claims 1 to 13, wherein the used lens reduces and forms an image of a subject image on the sensor.

15. The reading device according to any one of claims 1 to 14, and An inspection unit that inspects the state of a subject using the image information acquired by the reading device, An inspection device characterized by including.

16. The reading device according to any one of claims 1 to 14, and A storage device that stores the image information acquired by the reading device in a storage medium, A reading system characterized by including.

17. A manufacturing method of a reading device including a sensor including a plurality of pixels arranged along a main scanning direction and a plurality of lens blocks, A first step of dividing a rod lens array including a plurality of rod lenses arranged along a direction intersecting the optical axis into the plurality of lens blocks, ​ A second step of arranging the plurality of lens blocks at corresponding positions of the sensor; Each of the rod lenses included in each of the plurality of lens blocks includes a used lens that forms an image on the sensor and an unused lens that does not form an image on the sensor; In the second step; The used lenses of the plurality of lens blocks are arranged along the main scanning direction; The plurality of lens blocks are arranged spaced apart from each other along the main scanning direction. A manufacturing method characterized by this.

Images