JP6207359B2 - Illumination device, image sensor unit, and paper sheet identification device - Google Patents

Description

  The present invention relates to an illumination device, an image sensor unit, and a paper sheet identification device. Specifically, the present invention relates to an illuminating device that can irradiate light of a plurality of wavelengths such as visible light and infrared light, an image sensor unit having the illuminating device, and a paper sheet identification device having the image sensor unit.

  Some image sensor units for reading an image have a rod-shaped light guide that linearizes light emitted from a light source. In the configuration in which the light source is provided at one end in the longitudinal direction of the light guide, the illumination intensity of the light emitted from the light guide may become lower toward the opposite end. Therefore, Patent Document 1 and Patent Document 2 disclose a light guide body in which an inclined surface having an angle that does not transmit light is formed at an end opposite to the light source. According to such a configuration, the illuminance distribution of the light is distributed over the entire light guide by increasing the illumination intensity of the light near the end by reflecting the light that has reached the end opposite to the light source. To equalize.

  An image sensor unit that reads an image is also applied to a paper sheet identification device that determines the authenticity of a bill or the like. The banknote is provided with regions for different images obtained under visible light and infrared light for authenticity determination. For this reason, the image sensor unit applied to a paper sheet identification apparatus can irradiate a banknote with visible light and infrared rays, and can read the visible light image and infrared image of a banknote.

JP 2006-85975 A JP 2007-183470 A JP 2009-284373 A

By the way, an acrylic resin may be used for the light guide. The spectral transmittance of the acrylic resin varies depending on the material used for the light guide. For this reason, for example, when the infrared transmittance is lower than the visible light transmittance, the infrared illumination intensity emitted from the light guide becomes visible toward the end opposite to the side where the light source is provided. Compared to the illumination intensity of the light beam. For this reason, the illuminance distribution of infrared rays irradiated toward the banknote tends to be non-uniform compared to visible light. If it does so, there exists a possibility that the reading precision of an infrared image may fall.
In addition, when the transmittance of the light guide is different between visible light and infrared light, a difference occurs in illumination intensity, and illuminance distributions differ from each other. For this reason, there may be a difference in reading accuracy between the visible light image and the infrared image.
The acrylic resin has a lower transmittance in the infrared wavelength region than in other wavelength regions. For this reason, in the structure which uses an acrylic resin for a light guide, infrared illumination intensity tends to become low. In addition, although the method of forming a light guide with the inorganic material which does not have the wavelength dependence of an absorptivity can also be considered, since an inorganic material is generally expensive, it causes an increase in product price.

  In view of the above situation, the problem to be solved by the present invention is to make uniform the illuminance distribution of light in a wavelength region where the transmittance of the light guide is low. Another problem to be solved by the present invention is to reduce the difference in illuminance distribution between light in a wavelength region where the transmittance of the light guide is high and light in a low wavelength region.

The order to solve the changed title, the illuminating device of the present invention includes a light source for organic light-emitting element which emits light of a wavelength of the light emitting element and the visible region which emits light having a wavelength in the infrared region, the light the light source is emitted in the longitudinal direction A rod-shaped light guide that linearizes and emits light from a light exit surface provided on the surface, and the light guide has light transmittance with respect to light having a wavelength in the infrared region, and light having a wavelength in the visible region. consists lower material than the transmittance for the light source, opposite to the conjunction provided near one end of the longitudinal direction of the exit surface, in one surface opposite to the emission surface, one end portion in the longitudinal direction on the other end portion is a side, the reflectance to light of wavelength of the infrared region, characterized in Tei Rukoto high reflecting means provided than the reflectance for light having a wavelength of the visible region.

  The image sensor unit of the present invention is configured to receive the illumination device that illuminates the object to be illuminated, a light collecting body that collects light from the body to be illuminated, and reflected light collected by the light collecting body to receive electricity. And an image sensor for converting into a signal.

  The paper sheet identification apparatus of the present invention includes the image sensor unit, and reads light from the illuminated body while relatively moving the image sensor unit and the illuminated body.

  According to the present invention, the difference in illuminance distribution is reduced between light in a wavelength range where the transmittance of the light guide is high and light in a low wavelength range.

FIG. 1 is an exploded perspective view schematically showing the configuration of the lighting device 1. FIG. 2 is a schematic cross-sectional view of the light guide 12 (light guide 12a) cut along a plane perpendicular to the main scanning direction. FIG. 3 is a schematic cross-sectional view of the light guide 12b cut along a plane perpendicular to the main scanning direction. FIG. 4 is an exploded perspective view schematically showing the configuration of the lighting device 1 having the reflecting member 14 that is separate from the light guide 12b. FIG. 5 is an exploded perspective view schematically showing the configuration of the lighting device 1. It is the cross-sectional schematic diagram which cut | disconnected the light guide 12c by the surface parallel to the main scanning direction. FIG. 7 is an exploded perspective view schematically showing the configuration of the image sensor unit 3. FIG. 8 is a cross-sectional view schematically showing the internal structure of the image sensor unit 3, and is a view showing a cross section in a plane perpendicular to the main scanning direction. FIG. 9 is a cross-sectional view schematically showing the configuration of the paper sheet identification device 5, and is a view showing a cross section in a plane perpendicular to the main scanning direction. FIG. 10 is a cross-sectional view schematically showing a configuration of the paper sheet identification device 5 further including the transmission illumination device 52. FIG. 11 is a cross-sectional view schematically showing a configuration of a paper sheet identification device 5 having two sets of image sensor units 3. FIG. 12 is a graph showing the simulation result of the illuminance distribution of the first example. FIG. 13 is a graph showing a simulation result of the illuminance distribution of the second embodiment. FIG. 14 is a graph showing a simulation result of the illuminance distribution of the first example. FIG. 15 is a graph showing a simulation result of the illuminance distribution of the comparative example. FIG. 16 is a diagram showing the spectral transmittance of acrylic. FIG. 17 is a partially enlarged view showing the spectral transmittance of acrylic. FIG. 18 is a side view schematically showing another example according to the second embodiment. FIG. 19 is a side view schematically showing another example according to the third embodiment.

Hereinafter, embodiments to which the present invention can be applied will be described in detail with reference to the drawings. The embodiment of the present invention is an illumination device 1, an image sensor unit 3 having the illumination device 1, and a paper sheet identification device 5 having the image sensor unit 3. In each figure, three-dimensional directions are indicated by X, Y, and Z arrows. The X direction is the main scanning direction of the image sensor unit 3. The Y direction is the sub-scanning direction of the image sensor unit 3. The Z direction is the vertical direction of the image sensor unit 3.
In the embodiment of the present invention, “light” includes not only visible light but also electromagnetic waves in a wavelength region other than visible light (for example, an infrared wavelength region and an ultraviolet wavelength region).

(Lighting device)
<First Embodiment>
First, 1st Embodiment of the illuminating device 1 is described with reference to FIG. 1 and FIG. FIG. 1 is an exploded perspective view schematically showing the configuration of the lighting device 1. FIG. 2 is a schematic cross-sectional view of the light guide 12 (light guide 12a) of the illumination device 1 cut along a plane perpendicular to the main scanning direction. The illuminating device 1 irradiates visible light and infrared rays with respect to the banknote P as a to-be-illuminated body (paper sheets) in the state incorporated in the image sensor unit 3 (after-mentioned).

As shown in FIG. 1, the lighting device 1 includes a light source 11 and a light guide 12.
The light source 11 is disposed at a distance from an incident surface 121 (described later) which is one end surface of the light guide 12 in the main scanning direction (longitudinal direction), and emits light toward the incident surface 121 of the light guide 12. Irradiate. The light source 11 includes, for example, a light emitting element that emits light of each wavelength of red (R), green (G), blue (B), and infrared (Ir) that are sequentially turned on. Various known LEDs can be applied to each light emitting element. The light source 11 is mounted on the upper surface (upper surface in the Z direction) of a circuit board 33 (described later) of the image sensor unit 3.

  The light guide 12 is an optical member that linearizes light emitted from the light source 11. The light guide 12 is made of a transparent resin material such as acrylic resin, and is integrally formed by injection molding or the like. The light guide 12 as a whole has a rod-like configuration elongated in the main scanning direction.

The acrylic resin (hereinafter referred to as “acrylic resin”) applied to the light guide 12 has different spectral transmittance depending on the wavelength. For example, the transmittance of infrared rays in the acrylic resin is lower than the transmittance of visible light (light of each color of R, G, B emitted from the light source 11). Therefore, in the configuration in which the light source 11 is provided at one end of the light guide 12 in the main scanning direction, the infrared illumination intensity in the vicinity of the other end of the light guide 12 in the main scanning direction is compared with visible light. As a result, the illuminance distribution of the infrared rays is not uniform over the entire light guide 12. That is, when the light guide body 12 is formed of a material having a wavelength range where the transmittance is not constant, and light having a wavelength range where the transmittance is not constant is used for the light source 11, there is an influence over the length of the light guide body 12. Accumulate.
The light from the light source 11 includes a case where the transmittance is in a wavelength range where the transmittance is not constant due to a temperature shift or the like.

The light guide 12a is mixed with a material having a high absorptance for light in a wavelength region with a high transmittance. That is, a material having a visible light absorption rate higher than the infrared light absorption rate is uniformly mixed in the entire light guide 12.
When such a material is mixed in the acrylic resin, the visible light transmittance is increased in the light guide 12a, so that the visible light transmittance is lowered, and the difference in visible light and infrared transmittance is about the same. Or the difference can be reduced.

The product “Acryfilter IR” manufactured by Mitsubishi Rayon Co., Ltd. can be applied to the material as described above. And this "acrylic filter IR" is mixed with an acrylic resin so that it may become 99: 1 by weight ratio. The light guide 12a, which is an acrylic resin molded product thus obtained, can reduce the visible light transmittance to about 90%. Therefore, the absorptance is substantially the same for visible light and infrared light.
In addition, even if it is a case where materials other than an acrylic resin are used for the light guide 12, by changing a mixing ratio so that it may become the illumination intensity according to the transmittance | permeability of the light which requires the illumination intensity of visible light. Applicable.

  As shown in FIG. 1, one end surface of the light guide 12a in the main scanning direction is an incident surface 121 on which light emitted from the light source 11 is incident. The other end face of the light guide 12a in the main scanning direction is a reflection surface 123 that reflects light emitted from the light source 11. Further, as shown in FIG. 2, an emission surface 122 and a diffusion surface 124 are formed on the side surface of the light guide 12a.

The exit surface 122 is a surface that irradiates the bill P with light incident from the incident surface 121 (including light incident from the incident surface 121 and reflected by the reflection surface 123 and reflected or diffused by the diffusion surface 124). The light source 11 is located near one end of the emission surface 122 in the main scanning direction. The emission surface 122 is formed in an elongated strip shape extending in the main scanning direction. Since the emission surface 122 irradiates irradiation light toward the reading line O of the banknote P (see FIGS. 8 to 11), for example, it is formed in a curved surface that protrudes toward the reading line O of the banknote P. .
The dimension of the emission surface 122 in the main scanning direction is set according to the dimension of the banknote P. For example, the image sensor unit 3 is configured to read while relatively moving in the long side direction of the banknote P, and the dimension of the emission surface 122 in the main scanning direction is set to a dimension corresponding to the short side dimension of the banknote P. .

The diffusion surface 124 is a surface that reflects and diffuses light incident from the incident surface 121. As shown in FIG. 2, the diffusion surface 124 is formed so as to face the emission surface 122. On the diffusion surface 124, for example, a plurality of prismatic diffusion portions (not shown in the figure) are formed at a required interval. The interval between the plurality of diffusion portions decreases from one end side (incident surface 121 side) in the main scanning direction toward the other end side (reflecting surface 123 side).
In addition, as a spreading | diffusion part, the structure to which the printing pattern which consists of a light-reflective coating material by silk printing etc. is applied may be sufficient, for example. In this case, the density of the print pattern decreases as it approaches the incident surface 121 and increases as it increases. According to such a configuration, the illuminance distribution of the light irradiated from the emission surface 122 becomes non-uniform, in particular, the illumination intensity of the light decreases as the distance from the incident surface 121 increases, and the main scanning of the light guide 12a. The illuminance distribution of light can be made uniform over the direction.

  The other surfaces of the outer peripheral surface of the light guide body 12a each act as a reflection surface that reflects light.

  As described above, according to the first embodiment, the infrared illuminance distribution can be made uniform over the main scanning direction of the light guide 12a. Therefore, according to the image sensor unit 3 and the paper sheet identification device 5 in which the illumination device 1 of the first embodiment is incorporated, the difference in reading accuracy from the infrared image can be reduced.

<Second Embodiment>
Next, 2nd Embodiment of the illuminating device 1 is described with reference to FIG. FIG. 3 is a schematic cross-sectional view of the light guide body 12b of the illumination device 1 cut along a plane parallel to the main scanning direction. In addition, the same code | symbol is attached | subjected to the same structure as 1st Embodiment, and description is abbreviate | omitted.

The light guide 12b is
As an example of the reflecting means, the reflectance of light in a wavelength region where the transmittance of the light guide 12 is not constant (infrared rays in the present embodiment) is applied to the portion of the light diffusing surface 124 near the reflecting surface 123. A reflector 127 having a higher reflectance than that of light in other wavelength ranges (visible light in the present embodiment) is provided. For example, a film having a laminated structure of a long pass filter 129 and an aluminum vapor deposition layer 128 can be applied to the reflecting material 127 of the diffusion surface 124. The long pass filter 129 transmits infrared light and does not transmit light having a shorter wavelength than the infrared light. When the reflecting material 127 having such a configuration is provided on the diffusing surface 124, a difference occurs in the reflectance between visible light and infrared rays. Therefore, the infrared reflectance in the portion near the reflecting surface 123 in the diffusing surface 124 is reduced. It can be made higher than the portion near the incident surface 121. For this reason, in the part near the reflecting surface 123 of the diffusing surface 124, the reflectance of infrared rays is increased, and the amount of infrared rays emitted from the part near the reflecting surface 123 of the emitting surface 122 is increased (to prevent a decrease). Can do. Accordingly, it is possible to make the illuminance distribution of infrared rays uniform over the main scanning direction of the light guide 12b.

  As described above, a reflective material 127 having wavelength selectivity with a difference in reflectance (or absorptance) is formed as a dimming means in a portion near the reflecting surface 123 in the diffusing surface 124. A configuration in which a coating material having such characteristics is applied (a configuration in which a coating film is formed) can be applied. Various known paints can be applied to such paints.

  In addition, the structure which has the separate reflection member 14 as another example of a light reduction means may be sufficient. FIG. 4 is an exploded perspective view schematically showing the configuration of the lighting device 1 having the reflecting member 14 that is separate from the light guide 12b. As shown in FIG. 4, the light source 11 is disposed at one end of the light guide 12 b in the main scanning direction, and the reflecting member 14 is disposed near the reflecting surface 123 in the diffusing surface 124. The reflective member 14 has the same configuration as the reflective material 127 described above. For example, a member having a laminated structure of an aluminum vapor deposition layer and a long pass filter can be applied to the reflecting member 14. The reflecting member 14 is disposed so as to face a portion near the reflecting surface 123 in the diffusing surface 124 of the light guide 12b or to contact the portion of the diffusing surface 124. In such a configuration, the infrared light irradiated from the diffusion surface 124 of the light guide 12b to the outside of the light guide 12b is reflected by the reflecting member 14 and enters the light guide 12b again. For this reason, the effect similar to the above is acquired.

<Third Embodiment>
Next, 3rd Embodiment of the illuminating device 1 is described with reference to FIG. 5 and FIG. FIG. 5 is an exploded perspective view schematically showing the configuration of the lighting device 1. FIG. 6 is a schematic cross-sectional view of the light guide 12c of the illumination device 1 cut along a plane parallel to the main scanning direction. In addition, the same code | symbol is attached | subjected to the same structure as 1st Embodiment, and description is abbreviate | omitted.

As shown in FIG. 5 and FIG. 6, the light guide 12 c transmits visible light as an example of a dimming unit on the exit surface 122 of the light guide 12 near the entrance surface 121 in the main scanning direction. A light reducing material 126 having a higher rate than the infrared transmittance is formed. Alternatively, the light reducing material 126 may be formed in a dot pattern, and the density of the dot pattern may be reduced from the incident surface 121 side toward the reflecting surface 123 side. According to such a configuration, a part of the infrared light incident from the incident surface 121 is reflected by the light reducing material 126 formed on the emission surface 122. For this reason, since a difference occurs in the attenuation ratio between visible light and infrared light, the irradiation intensity of the infrared light emitted from the light emission surface 122 in the vicinity of the incident surface 121 is reduced, and the infrared light traveling toward the reflection surface 123 is reduced. As a result, it is possible to increase the irradiation intensity of infrared rays emitted from the emission surface 122 at a portion near the reflection surface 123. Accordingly, the illuminance distribution of infrared rays can be made uniform over the main scanning direction of the light guide 12c.
The specific range in which the light reducing material 126 is formed on the emission surface 122 is not limited. This range is appropriately set according to the irradiation intensity of infrared rays emitted from the light source 11 and the optical characteristics of the light reducing material 126.

As the light reducing material 126 provided on the emission surface 122, for example, a material that transmits visible light and totally reflects infrared light can be applied. As such a substance, for example, glass beads having a diameter of 50 μm can be applied.
In addition, the light-reducing material 126 can be applied with a coating material containing the above-described substances. As such a paint, for example, a product “heat ray (IR) reflection spray” of “Smile and Life Safety Analysis Center” can be applied. In this case, a configuration in which the amount of paint to be applied is gradually reduced (a configuration in which gradation is applied) as it goes from the incident surface 121 to the reflecting surface 123 may be employed. Further, such a paint may be applied in a dot pattern, and the dot pattern density may be reduced from the incident surface 121 side toward the reflecting surface 123 side. The point is that the infrared reflectance at the exit surface 122 of the light guide 12c may be high on the incident surface 121 side and low on the reflective surface 123 side in the main scanning direction.
In addition, a member that is a separate member from the light guide 12c and in which particles made of the above-described substances are mixed covers a portion of the light exit surface 122 of the light guide 12c near the entrance surface 121. The structure provided in may be sufficient.

(Image sensor unit)
The configuration of the image sensor unit 3 will be described with reference to FIGS. FIG. 7 is an exploded perspective view schematically showing the configuration of the image sensor unit 3. FIG. 8 is a cross-sectional view schematically showing the internal structure of the image sensor unit 3, and is a view showing a cross section in a plane perpendicular to the main scanning direction. The image sensor unit 3 can read an image of the banknote P with visible light and infrared rays from the banknote P.
The image sensor unit 3 includes the illumination device 1 according to any one of the embodiments described above, the frame 31, the light collector 32, the circuit board 33, and the cover member 35. An image sensor 34 is provided on the upper surface of the circuit board 33.
The frame 31 is a housing of the image sensor unit 3. The frame 31 has, for example, a rod-like configuration, and is formed of a resin material that is colored black and has a light shielding property. For example, polycarbonate can be used as the resin material. In the upper part of the frame 31 in the Z direction, the light guide 12 of the lighting device 1 (any one of the light guides 12a, 12b, and 12c) and the light collecting body 32 can be stored. A light collector housing chamber 312 is formed, and a substrate housing chamber 313 capable of housing the circuit board 33 is formed below the frame 31 in the Z direction. Are connected by an opening through which light can pass, and a light source accommodation chamber 314 capable of accommodating the light source 11 of the illumination device 1 is formed at one end of the frame 31 in the main scanning direction. When the illuminating device 1 is configured to include the reflecting member 14, a reflecting member accommodation chamber that can accommodate the reflecting member 14 of the illuminating device 1 is provided at a portion near the other end of the frame 31 in the main scanning direction. It is formed.

  The light collecting body 32 is an optical member that forms an image of visible light and infrared light from the banknote P on the surface of an image sensor 34 (described later). For example, a rod lens array is applied to the light collector 32. A general rod lens array has a configuration in which a plurality of erecting equal-magnification imaging type imaging elements (rod lenses) are linearly arranged in the main scanning direction. The light collector 32 may have any configuration as long as the imaging elements are linearly arranged, and the specific configuration is not limited. For example, the light collector 32 may have a configuration in which a plurality of imaging elements are arranged. In addition, various known optical members having a condensing function, such as various known microlens arrays, can be applied to the light collector 32.

  The circuit board 33 has a rectangular configuration that is long in the main scanning direction. The image sensor 34 and the light source 11 of the lighting device 1 are mounted on the upper surface (the upper surface in the Z direction) of the circuit board 33. The light source 11 is mounted in the vicinity of one end of the circuit board 33 in the main scanning direction so that light can be emitted toward the incident surface 121 of the light guide 12. On the other hand, the image sensor 34 is mounted with the light receiving surface facing upward in the Z direction so that light from the light collector 32 can be received. Further, the circuit board 33 is mounted with connectors for connecting wiring with the outside.

  The image sensor 34 converts the light imaged by the light collector 32 into an electrical signal. For example, an image sensor IC array is applied to the image sensor 34. The image sensor IC array is configured by mounting a plurality of image sensor ICs linearly on the surface of the circuit board 33 in the main scanning direction. The image sensor IC includes a plurality of light receiving elements (sometimes referred to as photoelectric conversion elements) corresponding to the reading resolution of the image sensor unit 3. As described above, the image sensor 34 is configured by arranging a plurality of image sensor ICs (light receiving elements) in a straight line in the main scanning direction. The image sensor 34 only needs to have a configuration in which a plurality of image sensor ICs are linearly arranged, and the other configuration is not particularly limited. For example, the image sensor ICs may be arranged in a plurality of rows like a staggered arrangement. Note that various well-known image sensor ICs having sensitivity to visible light and infrared light can be applied to the image sensor IC constituting the image sensor IC array as the image sensor 34.

  The cover member 35 is provided so as to cover the upper side of the frame 31. The cover member 35 has a function of protecting the light guide body 12 and the light collector 32 and a function of maintaining the flat surface in contact with the banknote P. The cover member 35 is a flat member, and for example, a glass plate or a transparent resin plate having an equivalent strength can be applied.

  In addition, the image sensor unit 3 is provided with an attachment portion for attachment to a paper sheet identification device 5 (described later), a connector for electrical connection to the paper sheet identification device 5, and the like. In addition, the structure of an attaching part or a connector is not specifically limited. The attachment portion may be any configuration that can attach the image sensor unit 3 to the paper sheet identification device 5. Moreover, the connector should just be the structure which can connect the image sensor unit 3 and the predetermined apparatus of the paper sheet identification apparatus 5 so that electric power and an electrical signal can be transmitted / received.

As shown in FIGS. 7 and 8, the light guide 12 is housed in the light guide housing chamber 311 of the frame 31. The light collector 32 is housed in the light collector housing chamber 312 of the frame 31. Further, the circuit board 33 on which the light source 11 and the image sensor 34 are mounted is housed in the board housing chamber 313.
When the light guide 12 is accommodated in the light guide accommodating chamber 311 and the circuit board 33 on which the light source 11 is mounted is accommodated in the substrate accommodating chamber 313, the light source 11 is accommodated in the light source accommodating chamber 314. It faces the incident surface 121 formed at one end of the. Therefore, the light emitted from the light source 11 is incident on the incident surface 121 formed at one end of the light guide 12. Further, in the case of a configuration in which a reflection member 14 that is separate from the light guide 12 is used, does the reflection member 14 face a portion near the other end of the diffusion surface 124 of the light guide 12? Or contact. Thereby, the light irradiated from the diffusing surface 124 of the light guide 12 is reflected by the reflecting member 14 and enters the light guide 12 again.

  In addition, it replaces with the structure to which the light guide 12b demonstrated in 2nd Embodiment is applied, It is an inner peripheral surface of the light guide accommodating chamber 311 of the flame | frame 31, and is among the diffusion surfaces 124 of the light guide 12. A configuration in which the reflective material 127 is formed on a surface (or a surface in contact) facing a portion near the reflective surface 123 may be used. Even with such a configuration, the same effect as the configuration to which the light guide 12b described in the second embodiment is applied can be obtained.

When irradiating the bill P with light, the light source 11 sequentially turns on the light emitting elements of each color and infrared. Light (R, G, B, Ir) emitted from the light source 11 is incident on the inside from the incident surface 121 of the light guide 12 and propagates inside by being reflected on the diffusing surface 124 and other reflecting surfaces. And it irradiates toward the reading line O of the banknote P from the output surface 122 of the light guide 12. FIG.
The reflected light from the reading line O of the bill P is imaged on the surface of the image sensor 34 by the light collecting body 32. The image sensor 34 converts the optical image formed by the light collector 32 into an electrical signal.
And the image sensor unit 3 repeats the operation | movement which irradiates the visible light and infrared rays of each color to the banknote P, and detects reflected light alternately in a short time. By such an operation, the image sensor unit 3 reads a predetermined pattern (for example, a hologram) provided on the banknote P as a visible light image and reads the banknote P as an infrared image.

  In addition, about the part which abbreviate | omitted illustration and description among the image sensor units 3, the same structure as a conventionally well-known image sensor unit is applicable.

(Paper identification device)
A paper sheet identification device 5 to which the image sensor unit 3 is applied will be described with reference to FIG. FIG. 9 is a cross-sectional view schematically showing the configuration of the paper sheet identification device 5, and is a view showing a cross section in a plane perpendicular to the main scanning direction. The paper sheet identification device 5 irradiates the bill P or the like with light, reads the light from the bill P, and identifies the type or authenticity of the bill P using the read light.

  As shown in FIG. 9, the paper sheet identification device 5 includes an image sensor unit 3 and a transport roller 51 that transports the banknote P. Then, the paper sheet identification device 5 transports the image sensor unit 3 in the reading direction (sub-scanning direction) between the transport rollers 51 via the cover member 35 with the banknote P interposed therebetween. A is set. At this time, the focal point on the banknote P side of the light collector 32 is set at the center of the transport path A. The operation of the paper sheet identification device 5 having such a configuration is as follows. The image sensor unit 3 applied to the paper sheet identification device 5 reads a predetermined pattern provided on the banknote P as a visible light image and reads the banknote P as an infrared image by the above-described operation. After that, the paper sheet identification device 5 displays the genuine bill image obtained by irradiating the bill P, which is a genuine note prepared in advance, with visible light and infrared rays, and the visibility of the bill P that is a determination target at the time of authenticity determination. The authenticity of the banknote P is determined by comparing the optical image with the infrared image. This is because the bill P, which is a genuine note, is provided with regions in which images obtained from visible light and infrared light are different from each other. In addition, about the part which abbreviate | omitted description and illustration, the same structure as the conventional paper sheet identification device is applicable.

Further, the paper sheet identification device 5 may further include a transmission illumination device 52. FIG. 10 is a cross-sectional view schematically showing a configuration of the paper sheet identification device 5 further including the transmission illumination device 52.
The transmitted illumination device 52 includes the light source 11 and the light guide 12. The same configuration as that of the light source 11 and the light guide 12 described above is applied to the light source 11 and the light guide 12 of the transmissive illumination device 52. The transmitted illumination device 52 is provided at a position facing the image sensor unit 3 so as to irradiate visible light and infrared rays toward the bill P. In particular, the transmissive illumination device 52 is disposed so that the optical axis of the light emitted from the emission surface 122 of the light guide 12 and the optical axis of the light collector 32 of the image sensor unit 3 coincide.

The operation of the paper sheet identification device 5 having such a configuration is as follows. The light source 11 of the illuminating device 1 and the light source 11 of the transmissive illuminating device 52 incorporated in the image sensor unit 3 sequentially turn on the visible light and infrared light emitting elements of each color.
Visible rays and infrared rays applied to the bill P from the illumination device 1 of the image sensor unit 3 are reflected by the surface of the bill P, enter the condenser 32, and form an image on the surface of the image sensor 34. The image sensor 34 acquires an image of visible light and an infrared image by reflected light from the banknote P by converting the formed optical image into an electrical signal. On the other hand, visible light and infrared rays irradiated to the bill P from the transmission illumination device 52 pass through the bill P and enter the light collecting body 32 of the image sensor unit 3, and form an image on the surface of the image sensor 34. The image sensor 34 obtains a visible light image and an infrared image by transmitted light from the banknote P by converting the formed optical image into an electrical signal.
Then, the image sensor unit 3 and the transmissive illumination device 52 alternately repeat the operation of irradiating the bill P with visible light and infrared light of each color to detect reflected light and transmitted light in a short time. By such an operation, the image sensor unit 3 reads a predetermined pattern (for example, a hologram) provided on the banknote P as a visible light image and reads the banknote P as an infrared image.
According to such a configuration, the paper sheet identification device 5 can read a visible light image and an infrared image by reflected light and transmitted light of the banknote P.

Further, the paper sheet identification device 5 may include two sets of image sensor units 3. FIG. 11 is a cross-sectional view schematically showing a configuration of a paper sheet identification device 5 having two sets of image sensor units 3.
As shown in FIG. 11, the two sets of image sensor units 3 are arranged so as to face each other across the conveyance path A of the bills P. In the two sets of image sensor units 3, visible light and infrared rays that have been irradiated from the illumination device 1 of one image sensor unit 3 and transmitted through the bills P are incident on the light collector 32 of the other image sensor unit 3. It is arranged as follows.
The operation of the paper sheet identification device 5 having such a configuration is as follows. That is, the light source 11 of the illuminating device 1 incorporated in the two sets of image sensor units 3 sequentially turns on the visible and infrared light emitting elements of each color. Visible light and infrared rays applied to the bill P from the illumination device 1 of the one image sensor unit 3 are reflected by the surface of the bill P and enter the light collecting body 32 of the one image sensor unit 3. An image is formed on the surface of the image sensor 34 of the unit 3. The image sensor 34 of one image sensor unit 3 acquires a visible light image and an infrared image by reflected light from the banknote P by converting the formed optical image into an electrical signal. Further, visible light and infrared rays irradiated on the banknote P from the illumination device 1 of one image sensor unit 3 pass through the banknote P and enter the light collecting body 32 of the other image sensor unit 3, and the other image sensor. An image is formed on the surface of the image sensor 34 of the unit 3. The image sensor 34 of the other image sensor unit 3 acquires a visible light image and an infrared image by transmitted light from the banknote P by converting the formed optical image into an electric signal.
According to such a configuration, the paper sheet identification device 5 can read the reflection images on both sides of the banknote P and can read the transmission image.

(Example)
Next, each example in which the effect of the present invention is verified will be described. 12-14 is a graph which shows the simulation result of the illumination intensity distribution of the illuminating device concerning each of the 1st-3rd Example. FIG. 15 is a graph showing a simulation result of the illuminance distribution of the lighting device according to the comparative example. In Examples and Comparative Examples, infrared (Ir) in the range of 800 to 1000 nm and green (G) light are used as visible light. The main scanning direction dimension of the light guide is 190 mm. The horizontal axis of each graph indicates the distance from the light incident surface, and the vertical axis indicates the relative illumination intensity normalized with the average output of visible light as 1 in the case of the light guides 12b and 12c.

FIG. 16 is a diagram showing the spectral transmittance of acrylic. FIG. 17 is a partially enlarged view of FIG. Here, as shown in FIGS. 16 and 17, 100 is a line indicating the spectral transmittance of acrylic. Spectral transmittance refers to the transmittance for each wavelength of light. The greater the transmittance, the smaller the light absorption inside the acrylic, and the smaller the transmittance, the greater the light absorption inside the acrylic. Yes.
For example, each synthetic resin has a wavelength range in which infrared rays are absorbed. In the case of acrylic, the wavelength range exists at 800 to 1000 nm. This is inherent to the material, and absorption of infrared rays occurs due to vibration caused by the structure of the synthetic resin. On the other hand, the wavelength region of 450 to 630 nm corresponding to visible light (R, G, B) is almost constant.
Note that the spectral transmittance of acrylic in FIGS. 16 and 17 indicates data of a test piece having a thickness (d) = 2 mm. For this reason, for example, in an A4 width light guide, the influence is accumulated over 220 to 230 mm.

<First embodiment>
The first example is an example of the illumination device according to the first embodiment, and is an example in which a material having a higher visible light absorption rate than an infrared absorption rate is uniformly mixed in the light guide. . FIG. 12 is a graph showing the simulation result of the illuminance distribution of the first example.
As shown in FIG. 15, in the comparative example, the visible light has a substantially uniform illuminance distribution, but the infrared illuminance distribution is compared with the visible light (G) in the vicinity of the end opposite to the light incident surface. And the decline is getting bigger. This is because, when acrylic is used as the light guide, the transmittance of infrared rays (Ir) in the range of 800 to 1000 nm, which is a wavelength range where the transmittance is not constant, is higher than the transmittance of visible light (R, G, B). This is considered to be because the infrared rays emitted from the exit surface decrease as the distance from the entrance surface decreases.
On the other hand, as shown in FIG. 12, in the first embodiment, the illuminance distribution of visible light is reduced in the vicinity of the end opposite to the light incident surface in the same manner as the illuminance distribution of infrared rays. Yes. For this reason, the illuminance distributions of visible light and infrared light have almost the same tendency as a whole.
As described above, it was confirmed that the difference in the illuminance distribution between the visible light and the infrared light can be reduced according to the structure in which the light guide is uniformly mixed with the material having the visible light absorption rate higher than the infrared light absorption rate. .

<Second embodiment>
The second example is an example of the illumination device according to the second embodiment, and is an example of a configuration in which the reflecting means is provided in a portion near the end opposite to the light incident surface. FIG. 13 is a graph showing a simulation result of the illuminance distribution of the second embodiment.
Here, a configuration is used in which the reflecting means is provided within a range of 30 mm from the end surface opposite to the light incident surface. In this example, the reflectance of visible light of the reflecting means was 0%, and the reflectance of infrared rays was 90%.
As apparent from FIGS. 13 and 15, the illuminance distribution of visible light does not change between the comparative example and the example. On the other hand, the illuminance distribution of the infrared rays in the example is less decreased in the vicinity of the end on the side opposite to the light incident surface as compared with the comparative example. For this reason, in the embodiment, the illuminance distributions of visible light and infrared light show substantially the same tendency.
In this way, by providing a reflection means having a higher infrared reflectance than that of visible light in a portion near the end opposite to the light incident surface, the illuminance between visible light and infrared light is provided. It was confirmed that the difference in distribution can be reduced.

<Third embodiment>
The third example is an example of the illumination apparatus according to the third embodiment, and is an example of a configuration in which a light reducing unit is provided in a portion near the light incident surface. FIG. 14 is a graph showing a simulation result of the illuminance distribution of the third example.
Here, a configuration in which a film as a dimming means is provided within a range of 80 mm from the light incident surface is used. This film had a visible light transmittance of 90%, a reflectance of 10%, an infrared transmittance of 10%, and a reflectance of 90%.
As apparent from FIGS. 14 and 15, the illuminance distribution of visible light does not change between the comparative example and the example. On the other hand, the infrared illuminance distribution of the example is lower in the portion near the light incident surface than the comparative example, and as a result, the infrared illuminance distribution is uniform. For this reason, in the third embodiment, the illuminance distributions of visible light and infrared light show substantially the same tendency.
As described above, the light emitting surface is provided with a light-reducing means having a visible line transmittance higher than that of infrared light at a portion near the light incident surface. It was confirmed that the difference in illuminance distribution can be reduced.

As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to these embodiment at all. The present invention can be variously modified without departing from the spirit of the invention.
For example, in each of the embodiments described above, the configuration in which acrylic is applied to the light guide is shown, but the light guide is not limited to a configuration made of acrylic. The present invention can be applied even when the light guide is made of a resin other than acrylic, quartz glass, or the like.
Moreover, in 1st Embodiment, although the structure with which the material with a high visible ray absorptivity is mixed with acrylic was shown, this invention is not limited to such a structure. The material mixed with the light guide may be configured to be determined according to the spectral transmittance of the light guide. If the light guide is made of a material other than acrylic, the material mixed with the light guide is determined according to the spectral transmittance of the material.
In the second embodiment, the infrared light reflectivity is higher in the region near the reflection surface of the diffusion surface of the light guide than in the visible light. It is not limited to. By forming a reflection surface at the other end that selectively reflects light absorbed by the material applied to the light guide, the material with low transmittance on the short wavelength side, such as ultraviolet rays, is short and long. The present invention can also be applied to the case where uniform illumination with the wavelength side is formed. That is, when the light source emits light of a plurality of wavelengths, and the transmittance of the light guide is lower than the other wavelengths for a specific part of the wavelengths of light emitted by the light source, Any structure may be used as long as a diffusion surface is provided on the other end face of the light guide so as to provide a difference in reflectance of specific wavelengths. In the third embodiment, the range of the light reducing material formed on the exit surface is not limited. The range of the reflecting material formed on the emission surface is appropriately set according to the illumination intensity of the light emitted from the light source.

Further, the position of the incident surface 121 is not limited to the end portion of the light guide 12, and for example, a structure provided at the center of the diffusion surface 124 in the main scanning direction may be used. In this case, in the second embodiment, the reflecting material 127, which is an example of the reflecting means, may be provided at both ends away from the incident surface 121 in the main scanning direction (see FIG. 18). Further, in the third embodiment, the dimming material 126 as an example of the dimming means is on the emission surface 122 in the main scanning direction described above and in the vicinity of the incident surface 121 (in this case, the main scanning direction). (In the vicinity of the central portion) may be provided (see FIG. 19).
The region 130 is a region that reflects and diffuses light incident from the incident surface 121, and is provided to make the illuminance distribution in the center of the light guide 12 uniform.

  Furthermore, in embodiment mentioned above, although the structure to which a banknote is applied as a paper sheet was shown, the kind of paper sheet is not limited. For example, as a paper sheet, it can be applied regardless of the type such as various securities and ID cards.

  The present invention is a technique effective as an illumination device, an image sensor unit, and a paper sheet identification device.

DESCRIPTION OF SYMBOLS 1: Illuminating device, 11: Light source, 12: Light guide, 121: Incident surface, 122: Outgoing surface, 123: Reflecting surface, 124: Diffusing surface, 126: Light reducing material, 127: Reflecting material, 14: Reflecting member 3: Image sensor unit, 31: Frame, 311: Light guide housing chamber, 312: Light collector housing chamber, 313: Substrate housing chamber, 314: Light source housing chamber, 32: Light collector, 33: Circuit board, 34: Image sensor, 35: Cover member, 5: Paper sheet identification device, 51: Conveyance roller, 52: Transmission illumination device, P: Bill (paper sheet), O: Reading line, A: Conveyance path

Claims (6)

A light source for organic light-emitting element which emits light of a wavelength of the light emitting element and the visible region which emits light having a wavelength in the infrared region,
A rod-shaped light guide that linearly emits light emitted from the light source from an emission surface provided on a longitudinal surface; and
Have
The light guide is made of a material whose transmittance for light of the wavelength in the infrared region is lower than the transmittance for light of the wavelength in the visible region ,
The light source is provided in the vicinity of one end in the longitudinal direction of the emission surface ,
In one surface opposite to the emission surface, to the other end which is opposite to the one end portion in the longitudinal direction, the reflectivity for light having a wavelength of reflectance the visible region with respect to light having a wavelength of the infrared region lighting device according to claim Tei Rukoto provided a higher reflection means than. A light source for organic light-emitting element which emits light of a wavelength of the light emitting element and the visible region which emits light having a wavelength in the infrared region,
A rod-shaped light guide that linearly emits light emitted from the light source from the emission surface provided in the longitudinal direction; and
Have
The light guide is made of a material whose transmittance for light of the wavelength in the infrared region is lower than the transmittance for light of the wavelength in the visible region ,
The light source is provided in the vicinity of one end in the longitudinal direction of the emission surface ,
In the exit face, the one end portion in the longitudinal direction, characterized in Tei Rukoto provided a high extinction device than the transmittance transmittance for light having a wavelength of the infrared region for light having a wavelength of the visible region A lighting device. A light source for organic light-emitting element which emits light of a wavelength of the light emitting element and the visible region which emits light having a wavelength in the infrared region,
A rod-shaped light guide that linearizes light emitted from the light source;
Have
The light guide is made of a material whose transmittance for light of the wavelength in the infrared region is lower than the transmittance for light of the wavelength in the visible region ,
Wherein the light guide, the illumination device characterized by the light for absorption of wavelengths of the infrared region is less material than the absorption of light of a wavelength of the visible region is mixed.   The illumination device according to any one of claims 1 to 3, wherein a material of the light guide is acrylic. The illuminating device according to any one of claims 1 to 4 , which irradiates an object to be illuminated with light;
A light collecting body for collecting light from the illuminated body;
An image sensor that receives the reflected light collected by the light collector and converts it into an electrical signal;
An image sensor unit comprising: A paper sheet identification device that reads light from the illuminated body while relatively moving the image sensor unit and the illuminated body,
The paper sheet identification device according to claim 5 , wherein the image sensor unit is the image sensor unit according to claim 5 .

Images