JP2023131422A - Image sensor illumination device, image sensor, paper-sheet identification device and paper-sheet processor - Google Patents

Abstract

To provide an image sensor illumination device which can diffuse light even in a depth direction and a sub-scanning direction in addition to a main scanning direction, and allows the easy manufacturing of a light guide body, an image sensor, a paper-sheet identification device and a paper-sheet processor.SOLUTION: In an image sensor illumination device having a light source and a light guide body extending in a main scanning direction, the light guide body has a light diffusion region for diffusing light which is made incident from the light source, and the light diffusion region is arranged from one end part of the light guide body to the other end part, and includes an irregular pattern having a ridge line extending in at least one oblique direction which forms a prescribed angle with respect to an axis in the main scanning direction.SELECTED DRAWING: Figure 4

Description

The present invention relates to an illumination device for an image sensor, an image sensor, a paper sheet identification device, and a paper sheet processing device.

Some lighting devices used in image sensors (optical line sensors) use a rod-shaped light guide to convert a point light source into a line light source. The longitudinal end surface of the light guide is provided with an entrance surface into which light from a point light source enters, and the side surface of the light guide is provided with a strip-shaped exit surface that emits light toward an irradiation target.

For example, Patent Documents 1 and 2 disclose lighting devices in which a concavo-convex pattern having ridge lines in a direction perpendicular to the longitudinal direction of the light guide is formed as a light diffusion portion of the light guide. Furthermore, Patent Document 1 discloses that in addition to the above-mentioned uneven pattern, an isotropically shaped depression or protrusion such as a bowl shape is formed at at least one end of the light guide as a light diffusion part of the light guide. This is disclosed.

JP2020-65226A Patent No. 6246351

However, with a concavo-convex pattern having ridgelines perpendicular to the longitudinal direction of the light guide, light is only diffused in the main scanning direction, and light is not sufficiently diffused particularly in the depth direction and sub-scanning direction. Ta.

Furthermore, processing the light guide to form isotropically shaped depressions and protrusions is time consuming and increases costs.

The present invention has been made in view of the above-mentioned current situation, and has an image that allows light to be diffused not only in the main scanning direction but also in the depth direction and the sub-scanning direction, and that makes it possible to easily manufacture a light guide. The object of the present invention is to provide a sensor illumination device, an image sensor, a paper sheet identification device, and a paper sheet processing device.

In order to solve the above problems and achieve the objective, (1) an image sensor illumination device according to a first aspect of the present disclosure includes a light source and a light guide extending in the main scanning direction. An illumination device for an image sensor, wherein the light guide has a light diffusion region that diffuses light incident from the light source, and the light diffusion region extends from one end of the light guide to the other. includes a concavo-convex pattern having at least one ridgeline extending in a diagonal direction and forming a predetermined angle with respect to the axis in the main scanning direction.

(2) In the illumination device for an image sensor according to (1) above, the ridgeline has at least a first direction forming a first angle with respect to the axis and a second direction forming a second angle with respect to the axis. and a second direction.

(3) In the illumination device for an image sensor according to (2) above, the first angle may have a different size from the second angle.

(4) In the illumination device for an image sensor according to (3) above, the first angle may be greater than or equal to 70° and less than 90°, and the second angle may be greater than or equal to 50° and less than 70°. It may be less than

(5) In the illumination device for an image sensor according to (2) above, the first angle may have the same size as the second angle.

(6) In the illumination device for an image sensor according to (1) above, the ridgeline may extend only in one oblique direction forming a predetermined angle with respect to the axis.

(7) In the illumination device for an image sensor according to (6) above, the predetermined angle may be greater than 60° and less than or equal to 75°.

(8) In the lighting device for an image sensor according to any one of (1) to (7) above, at least one of the one end and the other end of the light guide is adjacent to the light source. The width of the concavo-convex pattern in the sub-scanning direction may be different between an end adjacent to the light source among the one end and the other end and a central part of the light guide. Good too.

(9) In the illumination device for an image sensor according to (8) above, the width may be narrower at the end portions adjacent to the light source, and may be wider at the center portion.

(10) In the illumination device for an image sensor according to any one of (1) to (9) above, the uneven pattern includes a plurality of types of protrusions in which the angles formed by adjacent slopes across the ridge line are different from each other. It may also include a section.

(11) Furthermore, an image sensor according to a second aspect of the present disclosure includes the illumination device for an image sensor according to any one of (1) to (10) above.

(12) Furthermore, a paper sheet identification device according to a third aspect of the present disclosure includes the image sensor described in (11) above.

(13) Furthermore, a paper sheet processing device according to a fourth aspect of the present disclosure includes the paper sheet identification device according to (12) above.

According to the present disclosure, an illumination device for an image sensor, an image sensor, and a paper that can diffuse light not only in the main scanning direction but also in the depth direction and the sub-scanning direction and that can easily manufacture a light guide. A leaf identification device and a paper sheet processing device can be provided.

1 is a schematic side view of a lighting device according to Embodiment 1. FIG. FIG. 2 is a schematic diagram of a light guide used in the lighting device according to Embodiment 1, viewed from the incident surface side. FIG. 2 is a schematic diagram of a light guide used in the lighting device according to Embodiment 1, viewed from the exit surface side. FIG. 2 is a schematic diagram of a light guide used in the lighting device according to Embodiment 1, viewed from the opposing surface side. FIG. 2 is a schematic diagram of a light guide used in the lighting device according to Embodiment 1, viewed from the side. 2 is a schematic diagram of an example of a concavo-convex pattern provided on a light guide used in the lighting device according to Embodiment 1, viewed from the front. FIG. 7 is a schematic cross-sectional view taken along line AA of the uneven pattern shown in FIG. 6. FIG. 7 is a schematic cross-sectional view taken along line BB of the uneven pattern shown in FIG. 6. FIG. FIG. 3 is a schematic diagram showing an example of the traveling direction of light rays incident from one end surface of a light guide used in the lighting device according to Embodiment 1. FIG. FIG. 3 is a schematic diagram showing an example of the traveling direction of light rays incident from the other end surface of the light guide used in the lighting device according to the first embodiment. FIG. 3 is a schematic diagram showing an example of the traveling direction of light rays emitted from a light guide used in the lighting device according to the first embodiment. FIG. 2 is a schematic diagram showing an example of the traveling direction of light rays emitted from a light guide in an image sensor including the illumination device according to the first embodiment. FIG. 3 is a schematic diagram of another example of a concavo-convex pattern provided on a light guide used in the lighting device according to Embodiment 1, viewed from the front. FIG. 3 is a schematic diagram for explaining a model (arrangement of each member) used to simulate the intensity of light emitted from a light guide used in the lighting device according to the first embodiment. FIG. 3 is a schematic diagram for explaining an example of an uneven pattern of a light guide when simulating the intensity of light emitted from the light guide used in the lighting device according to the first embodiment. FIG. 7 is a schematic diagram for explaining another example of the concavo-convex pattern of the light guide when simulating the intensity of light emitted from the light guide used in the lighting device according to the first embodiment. FIG. 2 is a schematic perspective view of an image sensor according to a second embodiment. FIG. 3 is a schematic side view of an image sensor according to a second embodiment. FIG. 3 is a block diagram illustrating the configuration of a paper sheet identification device according to a third embodiment. FIG. 7 is a schematic perspective view showing the appearance of a paper sheet processing device according to a fourth embodiment.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of an image sensor lighting device, an image sensor, a paper sheet identification device, and a paper sheet processing device according to the present disclosure will be described in detail with reference to the drawings. The illumination device for an image sensor and the image sensor according to the present disclosure can be used in various fields, and can be used for the illumination device for an image sensor and an image sensor that scan paper sheets and acquire optical image information thereof. Therefore, in this embodiment, an example applied to these will be explained.

In the following description, the same reference numerals are appropriately used for components having the same or similar functions in different embodiments and drawings, and repeated explanations of the components are omitted as appropriate. In addition, the drawings explaining the structure appropriately show XYZ coordinate systems that are orthogonal to each other, and the X-axis direction, Y-axis direction, and Z-axis direction correspond to the sub-scanning direction, main scanning direction, and height direction of the image sensor, respectively. (depth direction).

(Embodiment 1)
First, an image sensor illumination device according to Embodiment 1 will be described. FIG. 1 is a schematic side view of a lighting device according to a first embodiment.

As shown in FIG. 1, the image sensor lighting device 1 according to the present embodiment includes a plurality of light sources 20 and a light guide 10 extending in the main scanning direction Y.

The light guide 10 guides the light from each light source 20 and irradiates the paper sheet P that is the irradiation target (illuminated target) with linear light, and the light emitted by each light source 20 is used as a linear light source. It is an optical member that can be The light guide 10 has an elongated bar shape extending in the main scanning direction Y of the image sensor, and is made of transparent resin such as acrylic resin.

Each light source 20 is provided adjacent to the end surface of the light guide 10 in the main scanning direction Y, and makes light enter the light guide 10 from the end surface of the light guide 10 . Each end surface onto which light from the light source 20 is incident functions as an entrance surface 11. That is, one end 15a and the other end 15b of the light guide 10 are adjacent to the light source 20.

Each light source 20 is configured by a light emitting element (not shown) such as a plurality of LEDs (Light Emitting Diodes) that can emit light in different wavelength bands (for example, ultraviolet light, red light, etc.). light, green light, blue light, and infrared light). Each light emitting element is electrically connected to a lead frame to which a positive voltage is applied and a lead frame to which a negative voltage is applied (both not shown).

Note that in FIG. 1, one light source 20 is arranged for each entrance surface 11, but a plurality of light sources 20 may be arranged for each entrance surface 11. In this case, normally the same number and type of light sources 20 are arranged for each entrance surface 11. Here, the same type of light source means a light source that emits light in the same wavelength band. Furthermore, different types of light sources 20 may be arranged on the two entrance surfaces 11.

On the other hand, in FIG. 1, the light source 20 is arranged for each entrance surface 11, but the light source 20 may be arranged only for one of the entrance surfaces 11. That is, only one end 15a or the other end 15b of the light guide 10 may be adjacent to the light source 20.

Next, the light guide 10 will be explained in detail. FIG. 2 is a schematic diagram of the light guide used in the lighting device according to the first embodiment, viewed from the entrance surface side. FIG. 3 is a schematic diagram of the light guide used in the lighting device according to the first embodiment, viewed from the output surface side. FIG. 4 is a schematic diagram of the light guide used in the lighting device according to Embodiment 1, viewed from the opposing surface side. FIG. 5 is a schematic diagram of a light guide used in the lighting device according to Embodiment 1, viewed from the side.

As shown in FIGS. 2 to 5, the light guide 10 has an elongated rod-like (substantially cylindrical) shape extending in the main scanning direction Y and having a substantially circular cross section. A substantially planar entrance surface 11 into which light from the light source 20 enters is provided on both end surfaces of the light guide 10, and an exit surface 12 and an exit surface 12 are provided on the side surfaces of the substantially cylindrical light guide 10. A facing surface 13 located on the opposite side of the surface 12 is formed. In addition to the output surface 12 and the opposing surface 13, the light guide 10 has two side surfaces 14 that connect the output surface 12 and the opposing surface 13, and each side surface 14 is composed of two side surfaces. However, the number of side parts of each side 14 is not particularly limited as long as it is one or more. Each side portion may be planar or curved. In this embodiment, a direction perpendicular to the main scanning direction Y and the sub-scanning direction X of the image sensor is defined as the height direction (depth direction) Z.

The output surface 12 is a surface that outputs the light incident from the light source 20 toward paper sheets. The output surface 12 may be convex as shown in FIG. 2, or may be planar. In the case of a convex shape, the exit surface 12 may be composed of a single curved surface (for example, it may be arcuate or elliptical in cross-sectional view), or may be composed of a plurality of surfaces. When the output surface 12 is composed of a plurality of surfaces, each surface may be planar or curved. As shown in FIG. 3, the output surface 12 is a belt-shaped surface extending along the main scanning direction Y and having a predetermined width in the sub-scanning direction X.

The opposing surface 13 is a surface that reflects light propagating inside the light guide 10 toward the output surface 12 . The opposing surface 13 may be planar as shown in FIG. 2, or may be convex. In the case of a convex shape, the facing surface 13 may be composed of a single curved surface (for example, it may be circular arc shape or elliptical arc shape in cross-sectional view), or may be composed of a plurality of surfaces. When the opposing surface 13 is composed of a plurality of surfaces, each surface may be planar or curved. As shown in FIG. 4, the opposing surface 13 is a belt-shaped surface extending along the main scanning direction Y and having a predetermined width in the sub-scanning direction X.

Further, as shown in FIG. 4, the opposing surface 13 of the light guide 10 is provided with a light diffusion area A that diffuses the light incident on the light guide 10 from each light source 20. The light diffusion region A is provided from one end 15a of the light guide 10 to the other end 15b. Like the opposing surface 13, the light diffusion region A is a belt-shaped region that extends along the main scanning direction Y and has a predetermined width in the sub-scanning direction X, and is set on substantially the entire surface of the opposing surface 13. There is.

As shown in FIG. 4, the light diffusion region A includes a concavo-convex pattern 30. Similar to the light diffusion region A, the uneven pattern 30 is provided from one end 15a of the light guide 10 to the other end 15b.

Note that the light diffusion region A (the uneven pattern 30) may be spaced a predetermined distance from each end surface of the light guide 10 (see FIG. 4), or may be arranged up to the edge of each end surface of the light guide 10. It's okay.

FIG. 6 is a schematic diagram of an example of a concavo-convex pattern provided on a light guide used in the lighting device according to Embodiment 1, viewed from the front. FIG. 7 is a schematic cross-sectional view of the uneven pattern shown in FIG. 6 taken along line AA. FIG. 8 is a schematic cross-sectional view of the uneven pattern shown in FIG. 6 taken along line BB.

As shown in FIG. 6, the uneven pattern 30 has at least one (two in FIG. 6) ridge lines 31 extending in the oblique direction and forming a predetermined angle with respect to the axis Ay in the main scanning direction Y. are doing. Further, as shown in FIGS. 7 and 8, the uneven pattern 30 has a structure in which the surface is formed into an uneven shape. Since the concavo-convex pattern 30 has the ridgelines 31 as described above, the light incident on the light guide 10 from each light source 20 can be diffused not only in the main scanning direction Y but also in the depth direction Z and the sub-scanning direction X. can. The reason for this will be explained in more detail using FIGS. 9 to 12.

FIG. 9 is a schematic diagram showing an example of the traveling direction of light rays incident from one end surface of a light guide used in the lighting device according to the first embodiment. FIG. 10 is a schematic diagram showing an example of the traveling direction of light rays incident from the other end surface of the light guide used in the lighting device according to the first embodiment. FIG. 11 is a schematic diagram showing an example of the traveling direction of light rays emitted from the light guide used in the lighting device according to the first embodiment. FIG. 12 is a schematic diagram showing an example of the traveling direction of the light beam emitted from the light guide in the image sensor including the illumination device according to the first embodiment. Note that FIGS. 9 and 10 show the trajectories of four representative light rays B1 to B4 incident from both end surfaces of the light guide 10.

As shown in FIGS. 9 and 10, since the ridgeline 31 of the uneven pattern 30 is oblique in at least one direction (two directions in FIGS. 9 and 10) with respect to the axis Ay of the main scanning direction Y, the light guide When the light rays B1 to B4 incident on the body 10 are reflected by the concavo-convex pattern 30, a component in a direction perpendicular to the main scanning direction Y (sub-scanning direction X) is added. As a result, as shown in FIG. 11, the light reflected by the uneven pattern 30 spreads in the width direction (sub-scanning direction X) of the light guide 10, and as shown in FIG. The uniformity of the light in the scanning direction X is improved (see double arrow).

Note that, as shown in FIG. 12, the light guide 10 may be arranged to be inclined so as to irradiate light in an oblique direction with respect to the height direction (depth direction) Z of the image sensor 100.

The uneven pattern 30 having the ridge lines 31 can be easily formed, for example, by cutting the opposing surface 13 of the light guide 10 with a cutting tool. Further, by using a mold, the light guide 10 having the concavo-convex pattern 30 can be molded all at once. That is, the light guide 10 having the uneven pattern 30 can be easily manufactured.

As shown in FIG. 6, the ridgeline 31 has at least a first direction that makes a first angle θ1 with respect to the axis Ay in the main scanning direction Y, and a second direction that makes a second angle θ2 with respect to the axis Ay. It may be extended in the direction of . As a result, compared to the case where the ridge line 31 extends in only one diagonal direction with respect to the axis Ay (see FIG. 13, etc. described later), the light incident on the light guide 10 is transmitted along the width of the light guide 10. Since the light spreads in the direction (sub-scanning direction X), the light can be uniformly diffused in the depth direction Z and the sub-scanning direction X.

Note that although FIG. 6 shows a case in which the ridgeline 31 extends only in the first direction and the second direction, the ridgeline 31 may extend in three or more diagonal directions with respect to the axis Ay. may be set.

The first angle θ1 may have a different size from the second angle θ2 as shown in FIG. ). However, if the first angle θ1 and the second angle θ2 have different sizes from each other, the depth will be lower than when the first angle θ1 and the second angle θ2 have substantially the same size. The uniformity of light in the Z direction and the sub-scanning direction X is further improved.

More specifically, from the results of a simulation described below, the first angle θ1 may be 70° or more and less than 90°, and the second angle θ2 may be 50° or more and less than 70°. Thereby, the uniformity of light in the depth direction Z and the sub-scanning direction X, particularly the uniformity of light in the depth direction Z, can be further improved. From a similar viewpoint, the first angle θ1 may be 75° or more and 85° or less, the second angle θ2 may be 55° or more and 65° or less, and the first angle θ1 is The second angle θ2 may be substantially 80° and the second angle θ2 may be substantially 60°.

FIG. 13 is a schematic diagram of another example of the uneven pattern provided on the light guide used in the lighting device according to the first embodiment, viewed from the front. Note that the cross section of the concavo-convex pattern shown in FIG. 13 taken along line BB is the same as that shown in FIG. 8.

As shown in FIG. 13, the ridgeline 31 may extend only in one oblique direction forming a predetermined angle θ with respect to the axis Ay of the main scanning direction Y. Thereby, the uneven pattern 30 having the ridge lines 31 can be more easily formed by cutting the opposing surface 13 of the light guide 10 with a cutting tool. That is, it is possible to manufacture the light guide 10 having the uneven pattern 30 more easily.

From the results of a simulation described later, the predetermined angle θ may be greater than 60° and less than or equal to 75°. Thereby, the uniformity of light in the depth direction Z and the sub-scanning direction X, particularly the uniformity of light in the depth direction Z, can be further improved. From a similar viewpoint, the predetermined angle θ may be greater than or equal to 65.° and less than or equal to 72°, or may be substantially 70°.

As shown in FIG. 4, the width W of the concavo-convex pattern 30 in the sub-scanning direction is determined by the width W of the concave-convex pattern 30 at the end adjacent to the light source 20 (in FIG. The end portions 15a and 15b) may be different from the center portion 16 of the light guide 10. Thereby, the uniformity of light in the main scanning direction Y can be improved. This is because the closer the illumination area is to the light source 20, the stronger the light intensity becomes, and the further away from the light source 20, the weaker the light intensity tends to be.

From this point of view, the width W of the concavo-convex pattern 30 is determined by the width W of the one end 15a and the other end 15b of the light guide 10 adjacent to the light source 20 (in FIG. 4, the ends 15a and 15b). ) and wider at the central portion 16 of the light guide 10 . That is, the width W of the concave-convex pattern 30 may be increased as the distance from the light source 20 increases, so that the amount of light diffused by the concave-convex pattern 30 in the main scanning direction Y may be increased. Further, the width W of the concavo-convex pattern 30 may become wider continuously as the distance from the light source 20 increases (see FIG. 4), or it may become wider stepwise.

As shown in FIGS. 7 and 8, the uneven pattern 30 may have a plurality of protrusions 33, and the plurality of protrusions 33 are formed by forming an angle φ between adjacent slopes 33a with the ridgeline 31 in between. A plurality of types (three types in FIGS. 7 and 8) of convex portions having different sizes may be included. As a result, the paper sheet can be irradiated with light from various directions, so that even bent or wrinkled parts of the paper sheet can be irradiated with light more uniformly.

More specifically, the plurality of types of convex portions may be repeatedly arranged in a predetermined order in the main scanning direction Y by a predetermined number (for example, one at a time). The angle φ formed by the adjacent slopes 33a may be, for example, 85° or more and 95° or less (for example, substantially 90°), or 60° or more and 75° or less (for example, substantially 67.5°). ), or may be greater than or equal to 70° and less than or equal to 85° (for example, substantially 78.75°). At least two angles may be selected from these three angles. Further, the plurality of types of convex portions may be repeatedly arranged in the main scanning direction Y so that the angles φ formed by the convex portions are in the order of large, small, and medium.

Here, the structure of the uneven pattern 30 will be explained in more detail.

As shown in FIGS. 7 and 8, the uneven pattern 30 may have a plurality of concave portions 34 as well as a plurality of convex portions 33, and as shown in FIGS. The plurality of recesses 34 may be arranged alternately in the main scanning direction Y. However, the concavo-convex pattern 30 entirely protrudes outward (on the side opposite to the output surface 12) from the opposing surface 13 (reference surface) of the light guide 10, and the bottom point of each recess 34 is the opposing surface 13 (reference surface). It is located above.

Each convex portion 33 has the ridge line 31 of the above-described concavo-convex pattern 30, and each concave portion 34 has a valley line 32. The ridge lines 31 and the valley lines 32 are substantially parallel to each other and alternately arranged in the main scanning direction Y.

The ridge line 31 is a linear continuation of the vertices of the convex portion 33, and is arranged in a straight line (see FIG. 13) or in a broken line (a line made up of a plurality of straight line segments, see FIG. 6). has been done. Similarly, the valley line 32 is a linear continuation of the bottom points of the concave portion 34, and may be linear (see FIG. 13) or polygonal line (a line composed of a plurality of straight line segments, FIG. 6). (see).

As shown in FIG. 6, each ridge line 31 and each valley line 32 may extend in a V-shape when the opposing surface 13 is viewed from the front. Furthermore, by arranging a plurality of V-shaped ridge lines 31 in the main scanning direction Y without changing their orientation, the V-shaped ridge lines 31 and the V-shaped valley lines 32 are arranged alternately in the main scanning direction Y. may be placed in In this way, since each ridge line 31 is V-shaped, the light spreads more uniformly.

Note that both ends of the V-shaped ridgeline 31 may be located on the same side with respect to the axis Ax in the sub-scanning direction X passing through the bending point of the V-shaped ridgeline 31 (see FIG. 6), One end of the V-shaped ridge line 31 may be located on one side with respect to the axis Ax, and the other end of the V-shaped ridge line 31 may be located on the other side with respect to the axis Ax.

Each convex portion 33 has, for example, a triangular prism shape (triangular prism shape), and as shown in FIGS. 7 and 8, the cross section perpendicular to the ridge line 31 has two sides (two slopes 33a) sandwiching the apex of the convex portion. It may be an isosceles triangle with equal lengths.

Note that the top of each convex portion 33 and the bottom of each concave portion 34 may be angular as shown in FIGS. 7 and 8, or may be rounded (R). Further, each slope 33a may be a curved surface instead of a plane, and for example, each convex portion 33 may have a semicircular or semielliptic cross section perpendicular to the ridge line 31.

However, if each slope 33a is a flat surface, each convex portion 33 can be more easily formed by cutting the opposing surface 13 of the light guide 10 with a cutting tool. Further, when the cross section of each convex portion 33 perpendicular to the ridgeline 31 is an isosceles triangle (the top of each convex portion 33 and the bottom of each concave portion 34 may be rounded (R)), the light guide 10 By cutting the opposing surface 13 with a cutting tool, the uneven pattern 30 can be formed more easily.

The height H of each convex portion 33 (that is, the depth of each concave portion 34) may be, for example, 0.01 mm or more and 0.2 mm or less, or 0.5 mm or more and 1.5 mm or less. It may be substantially 0.1 mm. The heights H of all the protrusions 33 (the depths of all the recesses 34) may be substantially the same.

The pitch of the convex portions 33 (concave portions 34) in the main scanning direction Y may be, for example, 0.1 mm or more and 1.5 mm or less, or 0.5 mm or more and 1 mm or less.

As shown in FIG. 8, a flat surface parallel to the opposing surface 13 does not need to exist between adjacent convex portions 33. Thereby, it is possible to effectively suppress the appearance of a shadow on the light emitted from the light guide 10 corresponding to the flat surface. From a similar point of view, in the case shown in FIG. 7, the bottom of the recess 34 between adjacent projections 33 may not be flat but may be rounded. That is, the bottom of each recess 34 may have a shape that swells in the +Z direction.

Note that the convex portions 33 and concave portions 34 of the concavo-convex pattern 30 may be entirely shifted toward the center of the light guide 10 (toward the exit surface 12 side), so that the concave-convex pattern 30 as a whole is shifted more than the opposing surface 13 (reference surface). It may be located on the exit surface 12 side.

Further, the uneven pattern 30 shown in FIGS. 7 and 8 may have a shape inverted about the opposing surface 13 (reference surface). In this case, the point that was the valley line 32 of the concave portion 34 before inversion corresponds to the ridgeline of the uneven pattern after inversion.

Here, the results of simulating the intensity of light emitted from the light guide 10 by changing the direction of the ridgeline 31 will be described.

FIG. 14 is a schematic diagram for explaining a model (arrangement of each member) used to simulate the intensity of light emitted from a light guide used in the lighting device according to the first embodiment. FIG. 15 is a schematic diagram for explaining an example of an uneven pattern of a light guide when simulating the intensity of light emitted from the light guide used in the lighting device according to the first embodiment.

As shown in FIG. 14, in this simulation, below the cover glass AA, there are two light guides BB, a condenser lens CC that collects the light emitted from the light guide BB and reflected by the medium, A light receiving section DD that receives the light focused by the condensing lens CC is disposed. Further, light sources EE were arranged so as to face the centers of both end surfaces of each light guide BB. As shown in FIG. 15, an uneven pattern GA having a V-shaped ridgeline FA was provided on the opposing surface of the light guide BB. The ridge line FA extends in a first direction forming a first angle θ1 with respect to the axis Ay in the main scanning direction Y, and in a second direction forming a second angle θ2 with respect to the axis Ay. . Here, θ1 was set to 80° or 70°, and θ2 was set to 50°, 60° or 70°.

Using this model, a detection surface HH corresponding to the position through which the medium passes was set above the cover glass AA, light was irradiated onto the detection surface HH, and the intensity of light on the detection surface HH was simulated. . The height of the detection surface HH was 2.6 mm, 1.3 mm, or 0 mm, with the height of the top surface of the cover glass AA being 0 mm. Then, at each position in the main scanning direction, the clearance ratio is calculated by dividing the light intensity at each height by the light intensity when the height is 1.3 mm. Furthermore, the clearance ratio average value was calculated by averaging the clearance ratios at all positions in the main scanning direction. The results are shown in Table 1.

It is preferable that the average value of the clearance ratio is small within the height range of 0 mm to 2.6 mm through which the medium passes, so from Table 1, the optimal combination of angles is the first angle θ1 = 80° and the second angle θ2 = It can be seen that the angle is 60°.

Next, a simulation performed by changing the concavo-convex pattern will be described.

FIG. 16 is a schematic diagram for explaining another example of the uneven pattern of the light guide when simulating the intensity of light emitted from the light guide used in the lighting device according to the first embodiment.

As shown in FIG. 16, a simulation was performed in the same manner except that the uneven pattern was changed. Here, a concavo-convex pattern GB having a linear ridgeline FB was provided on the opposing surface of the light guide BB. The ridgeline FB extends in a direction forming a predetermined angle θ with respect to the axis Ay in the main scanning direction Y. Here, θ was set to 75°, 70°, or 60°.

Using this model, as in the case above, we simulated the light intensity at the detection surface HH when the height of the top surface of the cover glass AA was 0 mm and the height was 2.6 mm, 1.3 mm, or 0 mm. , the average clearance ratio value was calculated. The results are shown in Table 2.

From Table 2, it can be seen that the optimal angle is the predetermined angle θ=70°.

As described above, according to the present embodiment, light can be diffused in the depth direction Z and the sub-scanning direction X in addition to the main scanning direction Y, and the light guide 10 can be easily manufactured for an image sensor. The lighting device 1 can be realized.

(Embodiment 2)
Next, an image sensor according to Embodiment 2 will be described. FIG. 17 is a schematic perspective view of an image sensor according to the second embodiment. FIG. 18 is a schematic side view of the image sensor according to the second embodiment.

As shown in FIGS. 17 and 18, the image sensor 100 according to the present embodiment detects various optical characteristics of the banknote BN being conveyed, and includes sensor units 110 and 120 arranged opposite to each other. There is. The sensor units 110 and 120 are each composed of a contact image sensor that faces a conveyance path of a paper sheet processing device, which will be described later. A gap is formed for conveying the sheet in the X direction within the plane, and this gap constitutes a part of the conveyance path of the paper sheet processing apparatus described later. The sensor units 110 and 120 are located above (+Z direction) and below (−Z direction) the conveyance path, respectively. The Y direction corresponds to the main scanning direction of the sensor units 110 and 120, and the X direction corresponds to the sub scanning direction of the sensor units 110 and 120.

As shown in FIGS. 17 and 18, each sensor unit 110, 120 includes two reflective illumination devices 111b, a condensing lens (objective lens) 112, a light receiving section 113, a cover glass 114 that covers these, and a substrate (see FIG. (not shown), and a housing (not shown) in which these are housed. Each lighting device 111b corresponds to the image sensor lighting device 1 of Embodiment 1, and includes a light guide 10 extending in the main scanning direction, and a plurality of light guides 111b facing at least one end surface of the light guide 10. It includes a plurality of types of light sources 20 (light emitting elements) that emit light of different wavelengths. The illumination device 111b of the sensor unit 110 and the illumination device 111b of the sensor unit 120 sequentially irradiate the A side and the B side of the banknote BN with light of a plurality of wavelengths. Each illumination device 111b irradiates light with multiple wavelengths, for example, light with different peak wavelengths. Specifically, for example, infrared light (multiple types of infrared light having different peak wavelengths may be used), red light, green light, blue light, white light, ultraviolet light, etc. can be used. The condensing lens 112 is composed of, for example, a rod lens array in which a plurality of rod lenses are arranged in the main scanning direction, and collects light emitted from the reflection illumination device 111b and reflected on the A side or the B side of the banknote BN. Focus the light. The light-receiving unit 113 includes, for example, a linear image sensor in which a plurality of light-receiving elements (light-receiving pixels) are arranged in the main scanning direction. Has sensitivity. For each light receiving element, for example, a silicon (Si) photodiode having sensitivity from at least the visible region to the infrared region with a wavelength of 1100 nm can be used. Each light receiving element is mounted on the substrate, receives the light focused by the condenser lens 112, converts it into an electric signal according to the amount of incident light, and outputs it to the substrate. Each light receiving element receives light of each wavelength in accordance with the irradiation timing of the light of each wavelength by the illumination device 111b. The substrate includes, for example, a drive circuit for driving the light receiving element and a signal processing circuit for processing and outputting a signal from the light receiving element. The board amplifies the output signal of the light receiving section 113 (each light receiving element) and then A/D converts it into digital data before outputting it.

The illumination device 111b irradiates the banknote BN with light of multiple wavelengths, and the light receiving unit 113 receives the light of multiple wavelengths irradiated from the illumination device 111b of the same sensor unit and reflected by the banknote BN. outputs reflection image data for each wavelength.

The sensor unit 120 further includes one transmission illumination device 111a. The illumination device 111a also corresponds to the image sensor illumination device 1 of Embodiment 1, and includes a light guide 10 extending in the main scanning direction, and a plurality of light guides facing at least one end surface of the light guide 10. It includes a plurality of types of light sources 20 (light emitting elements) that emit light of different wavelengths. The illumination device 111a is arranged on the optical axis of the condensing lens 112 of the sensor unit 110, and a part of the light emitted from the illumination device 111a passes through the banknote BN and passes through the condensing lens 112 of the sensor unit 110. The light is focused on the light receiving section 113 and detected by the light receiving section 113. The illumination device 111a sequentially or simultaneously irradiates the B side of the banknote BN with light having different wavelength bands. The illumination device 111a emits light of multiple wavelengths, for example, light having different peak wavelengths. Specifically, for example, infrared light (multiple types of infrared light having different peak wavelengths may be used), red light, green light, blue light, white light, ultraviolet light, etc. can be used.

The light receiving section 113 of the sensor unit 110 receives light of multiple wavelengths that is irradiated from the illumination device 111a and transmitted through the banknote BN, and outputs transmitted image data related to the light of multiple wavelengths for each wavelength.

Note that "light with multiple wavelengths" refers to light with mutually different wavelength bands, and may have mutually different peak wavelengths. Light with multiple wavelengths may be, for example, visible light with different colors, and infrared light and ultraviolet light with only a portion of the wavelength bands overlapping each other or light with wavelength bands that do not overlap with each other. It may be.

Since the image sensor 100 according to this embodiment includes lighting devices 111a and 111b corresponding to the image sensor lighting device 1 of Embodiment 1, it is possible to acquire image data in a lighting environment with high uniformity of brightness. can.

(Embodiment 3)
Next, the configuration of the paper sheet identification device according to this embodiment will be explained. Various paper sheets can be applied to paper sheets that are subject to this disclosure, such as banknotes, checks, gift certificates, bills, forms, securities, and card-like media, but in the following, banknotes are applicable. The present disclosure will be described using an example of a device. FIG. 19 is a block diagram illustrating the configuration of a paper sheet identification device according to the third embodiment.

As shown in FIG. 19, the paper sheet identification device 200 according to this embodiment includes a control section 210, a detection section 220, and a storage section 230.

The control unit 210 includes programs for realizing various processes stored in the storage unit 230, a CPU (Central Processing Unit) that executes the programs, and various hardware (for example, FPGA (Field)) controlled by the CPU. It is configured by a programmable gate array (Programmable Gate Array), etc. The control unit 210 controls each unit of the paper sheet identification device 200 according to a program stored in the storage unit 230. Further, the control unit 210 has a function of an identification unit using a program stored in the storage unit 230.

The detection unit 220 detects various characteristics of the banknote being conveyed, and may include a magnetic detection unit 221 and a thickness detection unit 222 in addition to the above-described image sensor 100 along the banknote conveyance path. . The image sensor 100 images a banknote and outputs an image signal (image data) as described above.

The storage unit 230 is composed of a nonvolatile storage device such as a semiconductor memory or a hard disk, and stores various programs and various data for controlling the paper sheet identification device 200.

The control unit 210 also performs identification processing using various signals related to banknotes acquired from the detection unit 220. The control unit 210 identifies at least the denomination and authenticity of the banknote. The control unit 210 may have a function of determining the fitness of banknotes. In that case, the control unit 210 detects dirt, folds, tears, etc. on the banknotes, as well as detects tape attached to the banknotes based on the thickness of the banknotes, thereby classifying the banknotes into genuine bills that can be reused in the market. It has a function to determine which unfit notes are to be treated as unsuitable for market circulation.

At this time, the control unit 210 uses the image (image data) of the banknote taken by the image sensor 100 in order to identify the denomination, authenticity, fitness, etc.

Since the paper sheet identification device 200 according to the present embodiment includes the image sensor 100 of the second embodiment, it is possible to perform banknote identification processing based on images with small variations in brightness. That is, it is possible to improve the accuracy of identification.

(Embodiment 4)
Next, the configuration of the paper sheet processing apparatus according to this embodiment will be explained. FIG. 20 is a schematic perspective view showing the appearance of the paper sheet processing apparatus according to the fourth embodiment. The paper sheet processing device according to this embodiment may have the configuration shown in FIG. 20, for example. A paper sheet processing device 300 shown in FIG. 20 includes a paper sheet identification device (not shown in FIG. 20) according to the third embodiment that performs banknote identification processing, and a plurality of banknotes to be processed are placed in a stacked state. a hopper 301 for discharging rejected banknotes, two reject units 302 from which rejected banknotes are discharged, an operation unit 303 for inputting instructions from an operator, and a housing 310 in which denominations, authenticity, and fitness are identified. It includes four stacking sections 306a to 306d for classifying and stacking banknotes, and a display section 305 for displaying information such as the banknote identification and counting results and the stacking status of each stacking section 306a to 306d.

Since the paper sheet processing device 300 according to the present embodiment includes the paper sheet identification device of Embodiment 3, it is possible to process banknotes more accurately based on the identification result of the paper sheet identification device. .

Although the embodiments have been described above with reference to the drawings, the present disclosure is not limited to the above embodiments. Furthermore, the configurations of each embodiment may be combined or modified as appropriate without departing from the gist of the present disclosure.

As described above, the present disclosure makes it possible to diffuse light not only in the main scanning direction but also in the depth direction and the sub-scanning direction in a lighting device for an image sensor, and to easily manufacture a light guide of the lighting device. It is a useful technology for

1: Illumination device 10: Light guide 11: Incident surface 12: Output surface 13: Opposing surface 14: Side surfaces 15a, 15b: End portion 16: Center portion 20: Light source 30: Concave-convex pattern 31: Ridge line 32: Valley line 33: Convex portion 33a: Slope 34: Concave portion 100: Image sensors 110, 120: Sensor units 111a, 111b: Illumination device 112: Condensing lens 113: Light receiving portion 114: Cover glass 200: Paper sheet identification device 210: Control portion 220: Detection unit 221: Magnetic detection unit 222: Thickness detection unit 230: Storage unit 300: Paper sheet processing device 301: Hopper 302: Reject unit 303: Operation unit 305: Display units 306a to 306d: Stacking unit A: Light diffusion area θ1 : First angle θ2: Second angle θ: Predetermined angle φ: Angle W: Width H of the concavo-convex pattern in the sub-scanning direction: Height of the convex portion X: Sub-scanning direction Y: Main-scanning direction Z: Height Direction (depth direction)
Ay: Axis in the main scanning direction Y Ax: Axis B1 to B4 in the sub-scanning direction X: 4 light rays P: Paper sheets (irradiation target)
BN: Banknote

Claims (13)

An illumination device for an image sensor including a light source and a light guide extending in the main scanning direction,
The light guide has a light diffusion region that diffuses the light incident from the light source,
The light diffusion region is provided from one end of the light guide to the other end, and includes at least one ridge line extending in a diagonal direction and forming a predetermined angle with respect to the axis in the main scanning direction. An illumination device for an image sensor, comprising a concavo-convex pattern having a concavo-convex pattern. The ridgeline is characterized in that it extends in at least a first direction that makes a first angle with the axis and a second direction that makes a second angle with the axis. The illumination device for an image sensor according to claim 1. 3. The illumination device for an image sensor according to claim 2, wherein the first angle has a different size from the second angle. The first angle is 70° or more and less than 90°,
4. The illumination device for an image sensor according to claim 3, wherein the second angle is greater than or equal to 50 degrees and less than 70 degrees. 3. The illumination device for an image sensor according to claim 2, wherein the first angle has the same magnitude as the second angle. 2. The illumination device for an image sensor according to claim 1, wherein the ridge line extends only in one oblique direction forming a predetermined angle with respect to the axis. The illumination device for an image sensor according to claim 6, wherein the predetermined angle is greater than 60 degrees and less than or equal to 75 degrees. At least one of the one end and the other end of the light guide is adjacent to the light source,
A width of the concavo-convex pattern in the sub-scanning direction is different between an end adjacent to the light source among the one end and the other end and a central part of the light guide. 8. The illumination device for an image sensor according to any one of items 1 to 7. 9. The illumination device for an image sensor according to claim 8, wherein the width is narrower at the end portions adjacent to the light source and wider at the center portion. The illumination device for an image sensor according to any one of claims 1 to 9, wherein the uneven pattern includes a plurality of types of protrusions having different angles formed by adjacent slopes with the ridge line in between. . An image sensor comprising the illumination device for an image sensor according to any one of claims 1 to 10. A paper sheet identification device comprising the image sensor according to claim 11. A paper sheet processing device comprising the paper sheet identification device according to claim 12.

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