Optical sensor, paper sheet identification device, and paper sheet processing device.

Abstract

The present invention provides an optical sensor, a paper sheet identification device, and a paper sheet processing device that can detect the optical characteristics of a medium printed with photoluminescent ink with high accuracy using a simple configuration. [Solution] An optical sensor for detecting the optical characteristics of a medium printed with photoluminescent ink, the optical sensor comprising: a light source capable of irradiating the medium with ultraviolet light; a visible light transmission filter section that transmits visible light while blocking ultraviolet and infrared light from the light emitted from the medium when the light source irradiates it with ultraviolet light; an infrared light transmission filter section that transmits infrared light while blocking ultraviolet and visible light from the light emitted from the medium when the light source irradiates it with ultraviolet light; a visible light receiving section that receives visible light transmitted through the visible light transmission filter section; and an infrared light receiving section that receives infrared light transmitted through the infrared light transmission filter section, wherein the visible light receiving section and the infrared light receiving section are provided independently.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to an optical sensor, a paper sheet identification device, and a paper sheet processing device.

BACKGROUND ART

[0002] Conventionally, photoluminescent compounds are known as security elements attached to paper sheets such as banknotes. A photoluminescent compound is excited by ultraviolet light or the like to generate fluorescence emission or phosphorescence emission. As methods capable of detecting these characteristics, for example, those disclosed in the following documents are known.

[0003] Patent Document 1 describes a solid-state imaging device comprising: an infrared light blocking filter laminated with a constant film thickness on each of a red photoelectric conversion element, a green photoelectric conversion element, and a blue photoelectric conversion element, for blocking infrared light; a red filter laminated on the infrared light blocking filter above the red photoelectric conversion element, for transmitting light of a red wavelength; a green filter laminated on the infrared light blocking filter above the green photoelectric conversion element, for transmitting light of a green wavelength; a blue filter laminated on the infrared light blocking filter above the blue photoelectric conversion element, for transmitting light of a blue wavelength; a visible light blocking filter laminated on the infrared photoelectric conversion element, for transmitting infrared light and blocking red light, green light, and blue light; and an ultraviolet light blocking filter laminated with a constant film thickness between each of the red photoelectric conversion element, the green photoelectric conversion element, and the blue photoelectric conversion element and the infrared light blocking filter, as well as between the infrared photoelectric conversion element and the visible light blocking filter, for transmitting infrared light and visible light and blocking ultraviolet light.

[0004] Figure 2 of Patent Document 2 describes an infrared sensor having a solid-state imaging element, wherein an imaging region provided on the solid-state imaging element has a near-infrared absorption filter and a color filter on which red, green, and blue pixels are formed, and a region where no near-infrared absorption filter is formed is provided between the near-infrared transmission filter and the solid-state imaging element.

[0005] Patent Document 3 describes a sensor module equipped with a light receiving unit, which includes a first visible light filter region that transmits visible light in a first visible wavelength band from light arriving from an object while blocking visible light and infrared light in other wavelength bands, a second visible light filter region that transmits visible light in a second visible wavelength band with a different wavelength band from the first visible wavelength band while blocking infrared light and visible light in other wavelength bands, and a third visible light filter region that transmits visible light in a third visible wavelength band with a different wavelength band from the first and second visible wavelength bands while blocking infrared light and visible light in other wavelength bands. The filter comprises a visible light filter region and an infrared light filter region that transmits infrared light in at least the first infrared wavelength band, the second infrared wavelength band, and the third infrared wavelength band, while blocking visible light; a first visible light receiving element that detects visible light transmitted through the first visible light filter region; a second visible light receiving element that detects visible light transmitted through the second visible light filter region; a third visible light receiving element that detects visible light transmitted through the third visible light filter region; and an infrared light receiving element that detects infrared light transmitted through the infrared light filter region. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Patent No. 6355862 [Patent Document 2] Patent No. 6546652 [Patent Document 3] Patent No. 6845302 [Overview of the project] [Problems that the invention aims to solve]

[0007] According to the filter configurations described in these patent documents, it is possible to separate visible light and infrared light coming from banknotes and then receive (detect) them independently and simultaneously. However, this filter configuration is difficult to manufacture and presents challenges in terms of thickness and cost. In particular, it is not easy to fabricate filters such as infrared light-shielding filters and near-infrared absorption filters into the pixels of an image sensor.

[0008] Thus, conventional methods had room for improvement in terms of detecting two or more different wavelength bands of light (particularly visible light and infrared light) arriving simultaneously from banknotes using a simple and highly accurate method.

[0009] Furthermore, as a security element attached to paper sheets, there are two-color mixed inks containing two different photoluminescent inks. When irradiated with a predetermined excitation light, these two-color mixed inks simultaneously emit light from two different wavelength bands (e.g., visible light and infrared light). Therefore, there has been a need for a simple and highly accurate method to detect and identify these two-color mixed inks containing two different photoluminescent inks.

[0010] This disclosure is made in view of the above-mentioned circumstances and aims to provide an optical sensor, a paper sheet identification device, and a paper sheet processing device that can detect the optical characteristics of a medium printed with photoluminescent ink with high accuracy using a simple configuration. [Means for solving the problem]

[0011] To solve the above-mentioned problems and achieve the objective, (1) an optical sensor according to a first aspect of the present disclosure is an optical sensor for detecting optical features of a medium printed with photoluminescent ink, the optical sensor comprising: a light source capable of irradiating the medium with ultraviolet light; a visible light transmission filter section that transmits visible light while blocking ultraviolet and infrared light from the light emitted from the medium when the light source irradiates it with ultraviolet light; an infrared light transmission filter section that transmits infrared light while blocking ultraviolet and visible light from the light emitted from the medium when the light source irradiates it with ultraviolet light; a visible light receiving section that receives visible light transmitted through the visible light transmission filter section; and an infrared light receiving section that receives infrared light transmitted through the infrared light transmission filter section, wherein the visible light receiving section and the infrared light receiving section are provided independently of each other.

[0012] (2) In the optical sensor described in (1) above, the wavelength of the light emitted from the medium and received by the visible light receiving unit and the infrared light receiving unit may be longer than the wavelength of the ultraviolet light irradiated from the light source.

[0013] (3) In the optical sensor described in (1) or (2) above, the visible light receiving unit and the infrared light receiving unit may be arranged on both sides of the light source.

[0014] (4) In the optical sensor described in (1) or (2) above, the visible light receiving unit may be positioned outside the optical path of the light that has been specularly reflected by the medium from the light emitted from the medium.

[0015] (5) In the optical sensor described in any of (1) to (4) above, the optical path for light incident on the visible light receiving unit and the optical path for light incident on the infrared light receiving unit may be separate.

[0016] (6) In the optical sensor described in any of (1) to (5) above, the visible light receiving unit and the infrared light receiving unit may each have a plurality of light receiving elements arranged in a line in the main scanning direction.

[0017] (7) The optical sensor according to the above (6), wherein the visible light receiving unit and the infrared light receiving unit may be arranged on both sides of the light source in the sub-scanning direction.

[0018] (8) The optical sensor according to any one of the above (1) to (5), wherein each of the visible light receiving unit and the infrared light receiving unit may have a single light receiving element arranged in a dot shape.

[0019] (9) The optical sensor according to any one of the above (1) to (8), may further comprise: a first optical system that condenses light emitted from the medium and forms an image on the light receiving element of the visible light receiving unit; and a second optical system that condenses light emitted from the medium and forms an image on the light receiving element of the infrared light receiving unit.

[0020] (10) The optical sensor according to any one of the above (1) to (9), wherein the visible light transmission filter unit may be arranged at a position separated from the light receiving element of the visible light receiving unit, and the infrared light transmission filter unit may be arranged at a position separated from the light receiving element of the infrared light receiving unit.

[0021] (11) The optical sensor according to any one of the above (1) to (10), wherein the visible light receiving unit may have three light receiving elements each provided with three color filters that split the visible light transmitted through the visible light transmission filter unit into blue light, green light, and red light.

[0022] (12) A paper sheet identification apparatus according to a second aspect of the present disclosure comprises the optical sensor according to any one of the above (1) to (11).

[0023] (13) A paper sheet processing apparatus according to a third aspect of the present disclosure comprises the paper sheet identification apparatus according to the above (12). [Advantageous Effects of Invention]

[0024] According to the present disclosure, it is possible to provide an optical sensor, a sheet identification device, and a sheet processing apparatus that are capable of detecting, with high accuracy and a simple configuration, the optical characteristics of a medium printed with photoluminescent ink. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] [Figure 1] It is a schematic cross-sectional view illustrating an example of the configuration of the optical sensor according to Embodiment 1. [Figure 2] It is a schematic cross-sectional view illustrating an example of the configuration of a monochrome line sensor type optical sensor according to Embodiment 2, showing a view seen from the main scanning direction. [Figure 3] It is a schematic diagram showing an example of the configuration on the visible light receiving unit side of the optical sensor shown in FIG. 2, showing a view seen from the sub-scanning direction. [Figure 4] It is a schematic diagram showing an example of the configuration on the infrared light receiving unit side of the optical sensor shown in FIG. 2, showing a view seen from the sub-scanning direction. [Figure 5] It is a schematic cross-sectional view illustrating an example of the configuration of a color line sensor type optical sensor according to Embodiment 2, showing a view seen from the main scanning direction. [Figure 6] It is a schematic diagram showing an example of the configuration on the visible light receiving unit side of the optical sensor shown in FIG. 5, showing a view seen from the sub-scanning direction. [Figure 7] It is a schematic diagram showing another example of the configuration on the visible light receiving unit side of the optical sensor shown in FIG. 5, where (a) shows a view seen from the sub-scanning direction, and (b) shows a plan view of the visible light receiving unit. [Figure 8] It is a schematic diagram illustrating another example of the configuration of the monochrome line sensor type optical sensor according to Embodiment 2, showing a view of the configuration of the end portion on the visible light receiving unit side as seen from the sub-scanning direction. [Figure 9] It is a schematic diagram illustrating another example of the configuration of the monochrome line sensor type optical sensor according to Embodiment 2, showing a view of the configuration of the end portion on the infrared light receiving unit side as seen from the sub-scanning direction. [Figure 10] It is a schematic diagram illustrating another example of the configuration of the color line sensor type optical sensor according to Embodiment 2, showing a view of the configuration of the end portion on the visible light receiving unit side as seen from the sub-scanning direction. [Figure 11] This is a schematic diagram illustrating yet another example of the configuration of the color line sensor type optical sensor according to Embodiment 2, where (a) shows the configuration of the end on the visible light receiving part side as seen from the sub-scanning direction, and (b) shows a plan view of the end of the visible light receiving part. [Figure 12] This is a schematic cross-sectional diagram illustrating an example of the configuration of a line sensor type optical sensor according to Embodiment 3, and shows the view from the main scanning direction. [Figure 13] This is a schematic cross-sectional diagram illustrating an example of the configuration of a line sensor type optical sensor according to Embodiment 4, and shows the view from the main scanning direction. [Figure 14] This is a schematic cross-sectional diagram illustrating an example of the configuration of a line sensor type optical sensor according to Embodiment 5, and shows the view from the main scanning direction. [Figure 15] This is a schematic cross-sectional diagram illustrating an example of the configuration of a monochrome point sensor type optical sensor according to Embodiment 6. [Figure 16] This is a schematic cross-sectional view illustrating an example of the configuration of a color point sensor type optical sensor according to Embodiment 6. [Figure 17] This is a schematic cross-sectional diagram illustrating another example of the configuration of the monochrome point sensor type optical sensor according to Embodiment 6. [Figure 18] This is a schematic cross-sectional diagram illustrating another example of the configuration of the color point sensor type optical sensor according to Embodiment 6. [Figure 19] This is a schematic perspective view showing the external appearance of an example of a paper sheet processing device according to Embodiment 7. [Figure 20] This is a schematic cross-sectional diagram illustrating an example of the configuration of the fluorescence detection unit of the paper sheet identification device according to Embodiment 7, showing a case in which a color line sensor type optical sensor is included. [Figure 21] This is a schematic cross-sectional diagram illustrating an example of the configuration of the imaging unit included in the paper sheet identification device according to Embodiment 7. [Figure 22] This is a block diagram illustrating an example of the configuration of a paper sheet identification device according to Embodiment 7. [Figure 23]This is a schematic cross-sectional diagram illustrating another example of the configuration of the fluorescence detection unit of the paper sheet identification device according to Embodiment 7, showing a case in which a point sensor type optical sensor is included. [Figure 24] This is a schematic diagram illustrating an example of the configuration of the end portion of the optical sensor of the color line sensor type according to Embodiment 8, and shows the view from the sub-scanning direction. [Modes for carrying out the invention]

[0026] Hereinafter, embodiments of the optical sensor, paper sheet identification device, and paper sheet processing device relating to this disclosure will be described in detail with reference to the drawings. Various media are applicable to this disclosure, such as banknotes, checks, gift certificates, bills of exchange, business forms, securities, and paper sheets such as card-type media, but in the following, this disclosure will be described using a sensor and device targeting banknotes as an example.

[0027] Furthermore, in this specification, photoluminescence is a concept that encompasses fluorescence and phosphorescence, but in the following, this disclosure will be explained using fluorescence (photoluminescence that can be detected during excitation light irradiation) as an example of photoluminescence. That is, in the following, we will explain the cases in which "photoluminescence" and "photoluminescence ink" are "fluorescence" and "fluorescent ink," respectively.

[0028] In the following explanation, the same reference numerals are used across different drawings to represent identical parts or parts with similar functions, and repeated explanations are omitted as appropriate. Furthermore, the drawings illustrating the structure show mutually orthogonal XYZ coordinate systems as appropriate.

[0029] (Embodiment 1) First, let's explain the fluorescent ink that may be printed on the banknotes to be detected. Genuine banknotes have fluorescent ink printed in a designated area, which is the target of detection, such as for determining authenticity or counterfeit status.

[0030] Fluorescent inks that may be detected, when excited by ultraviolet light (e.g., UVA, UVB, UVC, etc.), emit fluorescence in a predetermined wavelength band including at least the visible region (e.g., green (G)) and the infrared region (IR) while irradiated with ultraviolet light. Hereinafter, fluorescent inks having such optical characteristics may be referred to as special fluorescent inks. The fluorescence of special fluorescent inks may have peak wavelengths in both the visible and infrared regions.

[0031] More specifically, the special fluorescent ink may have a fluorescence spectrum with peaks in at least one of the blue, green, and red wavelength bands, or in the visible region with peaks in only one of the blue, green, or red wavelength bands. Furthermore, the special fluorescent ink may have a fluorescence spectrum with peaks in the infrared region or in the near-infrared region.

[0032] The special fluorescent ink may be a two-color mixed ink containing an ink that fluoresces in the visible range (hereinafter sometimes referred to as the first single-color ink) and an ink that fluoresces in the infrared range (hereinafter sometimes referred to as the second single-color ink).

[0033] The special fluorescent ink may contain, for example, two or more photoluminescent compounds. The printed area of ​​the special fluorescent ink may have, for example, a mixture of a first monochromatic ink containing a photoluminescent compound that fluoresces in the visible range and a second monochromatic ink containing a photoluminescent compound that fluoresces in the infrared range printed on it, or a first monochromatic ink containing a photoluminescent compound that fluoresces in the visible range and a second monochromatic ink containing a photoluminescent compound that fluoresces in the infrared range may be applied in layers.

[0034] On the other hand, this special fluorescent ink emits almost no light when exposed to visible light and transmits visible light, so it is invisible to the human eye in situations where visible light is present, such as under natural light or general artificial lighting. Furthermore, when the special fluorescent ink is exposed to ultraviolet light, the fluorescent components that emit light in the visible range can be seen by the human eye, but even then, the fluorescent components that emit light in the infrared range cannot be seen by the human eye. Therefore, this special fluorescent ink can function as a highly secure security element.

[0035] Next, the configuration of the optical sensor according to this embodiment will be described using Figure 1.

[0036] As shown in Figure 1, the optical sensor 1A according to this embodiment detects the optical characteristics of banknotes BN printed with fluorescent ink, and comprises a light source 10, a visible light transmission filter section 20, an infrared light transmission filter section 30, a visible light receiving section 40, and an infrared light receiving section 50.

[0037] Here, the banknote BN to be identified may be transported in the X direction within the XY plane.

[0038] The light source 10 irradiates the banknote BN with ultraviolet light (e.g., UVA) as excitation light. The light source 10 may be located on the same side as the visible light receiving unit 40 and the infrared light receiving unit 50 relative to the banknote BN.

[0039] The wavelength of ultraviolet light emitted by the light source 10 is not particularly limited, and the light source 10 may emit UVA, UVB, or UVC.

[0040] In this specification, UVA refers to ultraviolet light with wavelengths of approximately 315 nm to 400 nm, UVB refers to ultraviolet light with wavelengths of approximately 280 nm to 315 nm, and UVC refers to ultraviolet light with wavelengths of approximately 100 nm to 280 nm.

[0041] The visible light transmission filter section 20 transmits visible light while blocking ultraviolet and infrared light from the light emitted from the banknote BN when the light source 10 irradiates it with ultraviolet light. Therefore, of the fluorescence emitted from the fluorescent ink printed on the banknote BN, the visible-range fluorescence component is transmitted through the visible light transmission filter section 20, but the ultraviolet and infrared fluorescence components are blocked by the visible light transmission filter section 20.

[0042] The visible light transmission filter section 20 may consist of, for example, an ultraviolet cut filter 21 and an infrared cut filter 22 (see Figure 1), or it may consist of a filter that transmits only visible light. The visible light transmission filter section 20 may absorb or reflect ultraviolet light, or absorb or reflect infrared light.

[0043] The infrared light transmission filter section 30 transmits infrared light while blocking ultraviolet and visible light from the light emitted from the banknote BN when the light source 10 irradiates it with ultraviolet light. Therefore, of the fluorescence emitted from the fluorescent ink printed on the banknote BN, the infrared fluorescent component is transmitted through the infrared light transmission filter section 30, but the ultraviolet and visible fluorescent components are blocked by the infrared light transmission filter section 30.

[0044] The infrared light transmission filter section 30 may be composed of, for example, a filter 31 that transmits only infrared light (see Figure 1), or it may be composed of an ultraviolet cut filter and a visible cut filter. The infrared light transmission filter section 30 may absorb or reflect ultraviolet light, or it may absorb or reflect visible light.

[0045] The visible light receiving unit 40 receives visible light that has passed through the visible light transmission filter unit 20. Therefore, the visible light receiving unit 40 can selectively detect only the visible-range fluorescent components of the fluorescence emitted from the fluorescent ink printed on the banknote BN.

[0046] On the other hand, the infrared light receiving unit 50 receives infrared light that has passed through the infrared light transmission filter unit 30. Therefore, the infrared light receiving unit 50 can selectively detect only the infrared fluorescent component of the fluorescence emitted from the fluorescent ink printed on the banknote BN.

[0047] Therefore, with the optical sensor 1A, which comprises a light source 10, a visible light transmission filter section 20, an infrared light transmission filter section 30, a visible light receiving section 40, and an infrared light receiving section 50, it is possible to detect the visible fluorescence characteristics and infrared fluorescence characteristics of banknote BN with high accuracy. Furthermore, based on the detection results of the optical sensor 1A, it is possible to identify the fluorescent ink printed on the banknote BN, especially special fluorescent ink, for example, to determine its authenticity.

[0048] Furthermore, in the optical sensor 1A, the visible light receiving section 40 and the infrared light receiving section 50 are provided independently. Therefore, the optical sensor 1A does not require a complex configuration like the filter configurations described in Patent Documents 1 to 3, and is easy to manufacture. It is also advantageous for separately and independently detecting fluorescence components in the visible range and fluorescence components in the infrared range.

[0049] Based on the above, the optical sensor 1A can detect the optical characteristics of banknotes BN printed with fluorescent ink with high accuracy using a simple configuration.

[0050] The visible light receiving unit 40 is configured to receive visible-range fluorescence emitted from the fluorescent ink of the banknote BN while it is irradiated with ultraviolet light. For example, the visible light receiving unit 40 is configured to detect visible-range fluorescent components emitted from special fluorescent ink. In this case, the visible light receiving unit 40 can function as a sensor that is sensitive to at least visible-range fluorescent components emitted from special fluorescent ink. The visible light receiving unit 40 then outputs an electrical signal (which may also be a digital signal) corresponding to the amount of incident light (amount of light received). The light receiving element of the visible light receiving unit 40 may receive light, convert it into an electrical signal corresponding to the amount of incident light, and output it.

[0051] The infrared light receiving unit 50 is configured to receive infrared fluorescence emitted from the fluorescent ink of the banknote BN while it is irradiated with ultraviolet light. For example, the infrared light receiving unit 50 is configured to detect infrared fluorescence components emitted from special fluorescent ink. In this case, the infrared light receiving unit 50 can function as a sensor that is sensitive to infrared fluorescence components emitted from special fluorescent ink. The infrared light receiving unit 50 then outputs an electrical signal (which may also be a digital signal) corresponding to the amount of incident light (amount of light received). The light receiving element of the infrared light receiving unit 50 may receive light, convert it into an electrical signal corresponding to the amount of incident light, and output it.

[0052] The wavelength of the light emitted from the banknote BN (and its fluorescent ink) and received by the visible light receiving unit 40 and the infrared light receiving unit 50 may be longer than the wavelength of the ultraviolet light irradiated from the light source 10. Thus, the fluorescent ink that can be detected in this embodiment may absorb the energy of ultraviolet light and emit that energy as light in a longer wavelength band.

[0053] As shown in Figure 1, the visible light receiving unit 40 and the infrared light receiving unit 50 may be arranged on both sides of the light source 10. This allows ultraviolet light to be irradiated perpendicularly to the banknote BN from the light source 10, making it possible to detect the fluorescence (phosphorescence) emitted from the banknote BN with the same output in both the visible light receiving unit 40 and the infrared light receiving unit 50, regardless of whether the banknote BN is transported in the +X direction or the -X direction. On the other hand, as will be explained in Embodiment 4 later, if the light source 10 is arranged on both sides of the visible light receiving unit 40 and the infrared light receiving unit 50, the amount of ultraviolet light irradiated from the light sources 10 on both sides is not the same, which may result in differences in the fluorescence (phosphorescence) output depending on the transport direction of the banknote BN. Note that the effect of this output fluctuation is particularly large in the case of phosphorescence.

[0054] Similarly, the visible light receiving unit 40 and the infrared light receiving unit 50 may be arranged on either side of the light source 10, or the visible light receiving unit 40, the light source 10, and the infrared light receiving unit 50 may be arranged in this order.

[0055] However, the arrangement of the light source 10, the visible light receiving unit 40, and the infrared light receiving unit 50 is not particularly limited. For example, as in Embodiment 3 described later, the visible light receiving unit 40 may be positioned outside the optical path of the light emitted from the banknote BN that has been specularly reflected by the banknote BN. This arrangement will be described in detail in Embodiment 3.

[0056] Furthermore, as shown in Figure 1, the optical path 61 for light incident on the visible light receiving unit 40 and the optical path 62 for light incident on the infrared light receiving unit 50 may exist separately. This makes it possible to detect the fluorescence components in the visible range and the fluorescence components in the infrared range separately and more effectively. Optical path 61 may correspond to the optical path through which the fluorescence emitted from the fluorescent ink of the banknote BN travels (is incident on) the visible light receiving unit 40, and optical path 62 may correspond to the optical path through which the fluorescence emitted from the fluorescent ink of the banknote BN travels (is incident on) the infrared light receiving unit 50.

[0057] Furthermore, as shown in Figure 1, the visible light transmission filter section 20 may be positioned away from the light-receiving element of the visible light receiving section 40, and the infrared light transmission filter section 30 may be positioned away from the light-receiving element of the infrared light receiving section 50. In this case, an air layer may exist between the visible light transmission filter section 20 and the light-receiving element of the visible light receiving section 40, or other components may be present, as in the optical system described later. Similarly, an air layer may exist between the infrared light transmission filter section 30 and the light-receiving element of the infrared light receiving section 50, or other components may be present, as in the optical system described later.

[0058] Here, the term "photodetector" refers to an element (image sensor) that detects (converts into an electrical signal) the intensity of light in a predetermined wavelength band, and may include a photodetector such as a photodiode, and, if necessary, a color filter (color resist) provided on the light-receiving surface of the photodetector to suppress the transmission of light in wavelength bands other than the predetermined wavelength band to be detected (e.g., the blue and infrared wavelength bands) (e.g., the green and red wavelength bands). Furthermore, the photodetector may have a clear filter on its light-receiving surface that transmits light in wavelength bands from the ultraviolet region (e.g., UVA) to the infrared region (e.g., the near-infrared region), or it may not have an optical filter such as a color filter or clear filter on its light-receiving surface.

[0059] For example, the visible light receiving unit 40 may have three light-receiving elements, each equipped with three color filters that spectrally separate the visible light transmitted through the visible light transmission filter unit 20 into blue light, green light, and red light. In this case, the visible light receiving unit 40 can separate the fluorescence emitted from the fluorescent ink printed on the banknote BN into a blue fluorescence component, a green fluorescence component, and a red fluorescence component, and then detect them independently and simultaneously. Therefore, the visible light receiving unit 40 can function as a color sensor and output the amounts of blue fluorescence emission, green fluorescence emission, and red fluorescence emission, respectively.

[0060] Note that "fluorescence emission amount" is a value that indicates the intensity (brightness) of the fluorescence in question.

[0061] On the other hand, the visible light receiving unit 40 may have a light-receiving element that does not have a color filter that spectrally separates visible light into multiple wavelengths of light (for example, blue light, green light, and red light). In this case, the visible light receiving unit 40 can detect the fluorescence emitted from the fluorescent ink printed on the banknote BN as a fluorescence component across the entire visible range. Therefore, the visible light receiving unit 40 can function as a monochrome sensor and output the amount of fluorescence emission of visible light including blue light, green light, and red light. Thus, special fluorescent inks that emit light in the blue wavelength band, the green wavelength band, or the red wavelength band can be effectively detected.

[0062] Similarly, the infrared light receiving unit 50 may have a light-receiving element that does not have a filter for spectrally separating infrared light into multiple wavelengths. In this case, the infrared light receiving unit 50 can detect fluorescence emitted from the fluorescent ink printed on the banknote BN as a fluorescence component in a predetermined infrared region. Therefore, the infrared light receiving unit 50 can output a predetermined amount of fluorescence emission in the infrared region. Furthermore, it can effectively detect special fluorescent inks that emit light in the infrared region.

[0063] The predetermined infrared region, that is, the infrared region detectable by the infrared light receiving unit 50, may depend on the spectral sensitivity characteristics of the light receiving element, and more specifically, it may be a wavelength range of approximately 750 nm to 1100 nm.

[0064] When the visible light receiving unit 40 functions as a color sensor as described above, the authenticity of the fluorescent ink, particularly special fluorescent ink, printed on the banknote BN can be determined based on at least one of the blue fluorescence emission amount, the green fluorescence emission amount, and the red fluorescence emission amount, and the fluorescence emission amount in the infrared region. For example, the authenticity of the special fluorescent ink printed on the banknote BN can be determined based on the ratio of at least one of the blue fluorescence emission amount, the green fluorescence emission amount, and the red fluorescence emission amount (e.g., the green fluorescence emission amount) to the fluorescence emission amount in the infrared region.

[0065] When the visible light receiving unit 40 functions as a monochrome sensor as described above, the authenticity of the fluorescent ink, particularly special fluorescent ink, printed on the banknote BN can be determined based on the amount of visible light fluorescence emission, including blue, green, and red light, and the amount of fluorescence emission in the infrared region. For example, the authenticity of the special fluorescent ink printed on the banknote BN can be determined based on the ratio of the amount of visible light fluorescence emission, including blue, green, and red light, and the amount of fluorescence emission in the infrared region.

[0066] In this specification, blue generally refers to light (color) with a wavelength of approximately 400 nm to 500 nm, and may also refer to light (color) having a peak wavelength in this wavelength range. Green generally refers to light (color) with a wavelength of approximately 500 nm to 600 nm, and may also refer to light (color) having a peak wavelength in this wavelength range. Red generally refers to light (color) with a wavelength of approximately 600 nm to 750 nm, and may also refer to light (color) having a peak wavelength in this wavelength range. Furthermore, infrared light generally refers to light with a wavelength of 750 nm or more, and may also refer to light having a peak wavelength in this wavelength range. Near-infrared light generally refers to light with a wavelength of approximately 750 nm to 1500 nm, and may also refer to light having a peak wavelength in this wavelength range.

[0067] The optical sensor 1A may be a so-called line sensor (see Embodiments 2-5) or a so-called point sensor (see Embodiment 7), as described in the embodiments below.

[0068] The optical sensor 1A may include an output unit that outputs visible light reception data detected by the visible light receiving unit 40 and infrared light reception data detected by the infrared light receiving unit 50. More specifically, the optical sensor 1A may include, as an output unit, an A / D converter that converts the analog signal output from the visible light receiving unit 40 and the analog signal output from the infrared light receiving unit 50 into digital signals, an amplifier that amplifies the analog and digital signals, an output interface that outputs the A / D converted digital signals, and so on. (Embodiment 2) The configuration of the optical sensor according to this embodiment will be explained using Figure 2.

[0069] As shown in Figure 2, the optical sensor 1B according to this embodiment, like the optical sensor 1A according to Embodiment 1, includes a light source 10, a visible light transmission filter section 20, an infrared light transmission filter section 30, a visible light receiving section 40, and an infrared light receiving section 50, but is configured as a line sensor and can function as a contact image sensor.

[0070] Therefore, in this embodiment, the light source 10 is longer than the length of the banknote BN in the Y direction and illuminates the entire Y-direction of the banknote BN in a straight line extending in the Y direction. The light source 10 may also comprise a transparent, linear rod-shaped light guide and light-emitting elements (usually multiple, for example, LEDs (Light Emitting Diodes)) facing at least one of the end faces of the light guide, and the light may be illuminated onto the banknote BN via the light guide. As a result, the light source 10 can diffuse and reflect ultraviolet light incident from at least one end face (incident end) within the light guide and emit it from one side of the light guide (output end).

[0071] Furthermore, in this embodiment, the visible light receiving unit 40 and the infrared light receiving unit 50 are each longer than the length of the banknote BN in the Y direction, and receive light emitted along the entire Y direction of the banknote BN.

[0072] Thus, when the optical sensor constitutes a line sensor, the Y direction corresponds to the main scanning direction of the optical sensor (visible light receiving section and infrared light receiving section), and the X direction corresponds to the sub-scanning direction of the optical sensor (visible light receiving section and infrared light receiving section).

[0073] The visible light receiving unit 40 and the infrared light receiving unit 50 may each output an electrical signal corresponding to the amount of incident light as image data. In this case, the visible light receiving unit 40 and the infrared light receiving unit 50 may each have a plurality of pixels arranged in a row in the main scanning direction (Y direction). That is, the visible light receiving unit 40 and the infrared light receiving unit 50 may each output an electrical signal corresponding to the amount of incident light in a plurality of channels corresponding to a plurality of pixels (positions in the main scanning direction (Y direction)). Note that a channel (row) is a number assigned sequentially to the light receiving element (image sensor) in the Y direction. In this case, the visible light receiving unit 40 and the infrared light receiving unit 50 may each output line data, which is data relating to the light received simultaneously in each channel, as image data. While transporting the banknote BN in the sub-scanning direction (X direction), the image data of the entire banknote BN may be output by repeatedly irradiating it with light from the light source 10 and receiving it with light from the visible light receiving unit 40 and the infrared light receiving unit 50.

[0074] The image data acquired by the visible light receiving unit 40 and the infrared light receiving unit 50 consists of multiple pixels arranged in a matrix in the Y direction (main scanning direction) and the X direction (sub-scanning direction). The address of each pixel is identified by the channel (column) of the visible light receiving unit 40 or the infrared light receiving unit 50 corresponding to the position in the Y direction, and the line (row) corresponding to the position in the X direction. The line (row) is a number sequentially assigned to the line data output sequentially by the visible light receiving unit 40 and the infrared light receiving unit 50, respectively.

[0075] As shown in Figure 2, the optical sensor 1B comprises a rectangular parallelepiped frame 63 that houses a light source 10, a visible light transmission filter section 20, an infrared light transmission filter section 30, a visible light receiving section 40, and an infrared light receiving section 50, and a window material 64 that covers an opening provided on one side of the frame 63. The window material 64 is made of glass or the like and transmits light in the wavelength range from the ultraviolet region (e.g., UVA) to the infrared region (e.g., near-infrared).

[0076] Furthermore, as shown in Figure 2, the optical sensor 1B further includes a first optical system 71 that collects light emitted from the banknote BN and forms an image on the light-receiving element 41 of the visible light receiving unit 40, and a second optical system 72 that collects light emitted from the banknote BN and forms an image on the light-receiving element 51 of the infrared light receiving unit 50.

[0077] The first optical system 71 and the second optical system 72 may each consist of rod lens arrays 73 and 74, in which a plurality of rod lenses are arranged in the main scanning direction (Y direction).

[0078] Furthermore, the optical sensor 1B includes an output unit (not shown) that outputs visible light reception data detected by the visible light reception unit 40 and infrared light reception data detected by the infrared light reception unit 50.

[0079] As shown in Figure 2, in this embodiment, the visible light receiving unit 40 comprises a plurality of light-receiving elements 41 and a substrate 42 on which the plurality of light-receiving elements 41 are provided, and the infrared light receiving unit 50 comprises a plurality of light-receiving elements 51 and a substrate 52 on which the plurality of light-receiving elements 51 are provided.

[0080] Furthermore, in this embodiment, as shown in Figure 3, the multiple light-receiving elements 41 of the visible light receiving unit 40 are arranged in a line in the main scanning direction (Y direction), and as shown in Figure 4, the multiple light-receiving elements 51 of the infrared light receiving unit 50 are arranged in a line in the main scanning direction (Y direction).

[0081] In optical sensor 1B, similar to optical sensor 1A according to Embodiment 1, the visible light receiving unit 40 and the infrared light receiving unit 50 are arranged on both sides of the light source 10.

[0082] More specifically, the visible light receiving unit 40 and the infrared light receiving unit 50 are arranged on both sides of the light source 10 in the sub-scanning direction (X direction).

[0083] Similarly, the visible light receiving unit 40 and the infrared light receiving unit 50 may be arranged on either side of the light source 10 in the sub-scanning direction (X direction), or the visible light receiving unit 40, the light source 10, and the infrared light receiving unit 50 may be arranged in this order in the sub-scanning direction (X direction).

[0084] Furthermore, in this embodiment, similar to the optical sensor 1A according to Embodiment 1, as shown in Figure 2, the visible light transmission filter section 20 is positioned away from the light-receiving element 41 of the visible light receiving section 40, and the infrared light transmission filter section 30 is positioned away from the light-receiving element 51 of the infrared light receiving section 50.

[0085] More specifically, as shown in Figure 2, visible light transmission filter sections 20 may be placed on each end face of the rod lens array 73 on the side of the photodetector 41, and the visible light transmission filter sections 20 may be placed away from the photodetector 41. Similarly, infrared light transmission filter sections 30 may be placed on each end face of the rod lens array 74 on the side of the photodetector 51, and the infrared light transmission filter sections 30 may be placed away from the photodetector 51.

[0086] Alternatively, the visible light transmission filter section 20 may be placed on each end face of the rod lens array 73 opposite to the light-receiving element 41 (the banknote BN side), or the infrared light transmission filter section 30 may be placed on each end face of the rod lens array 74 opposite to the light-receiving element 51 (the banknote BN side). This also allows the visible light transmission filter section 20 and the infrared light transmission filter section 30 to be placed at positions away from the light-receiving element 41 of the visible light receiving section 40 and the light-receiving element 51 of the infrared light receiving section 50, respectively.

[0087] As shown in Figures 2 and 4, each light-receiving element 51 of the infrared light-receiving unit 50 is a light-receiving element that does not have a filter that spectrally separates infrared light into multiple wavelengths of light. Therefore, the infrared light-receiving unit 50 can output a predetermined amount of fluorescence emission in the infrared region.

[0088] The infrared light receiving unit 50 may include a plurality of pixels 53 arranged in a row in the main scanning direction (Y direction), and each pixel 53 may be composed of one light receiving element 51.

[0089] As shown in Figures 2 and 3, each light-receiving element 41 of the visible light receiving unit 40 may be a light-receiving element that does not have a color filter that spectrally separates visible light into multiple wavelengths of light (for example, blue light, green light, and red light). In this case, the visible light receiving unit 40 can function as a monochrome sensor and output the amount of fluorescence emission of visible light including blue light, green light, and red light.

[0090] The visible light receiving unit 40 may include a plurality of pixels 43 arranged in a row in the main scanning direction (Y direction), and each pixel 43 may be composed of one light receiving element 41.

[0091] On the other hand, as shown in Figures 5, 6, and 7, the visible light receiving unit 40 may have three light-receiving elements 45B, 45G, and 45R, each equipped with three color filters 44B, 44G, and 44R that spectrally separate the visible light transmitted through the visible light transmission filter unit 20 into blue light, green light, and red light, respectively. In this case, the visible light receiving unit 40 can function as a color sensor and output the amount of blue fluorescence emission, the amount of green fluorescence emission, and the amount of red fluorescence emission, respectively.

[0092] Color filter 44B may transmit blue light and infrared light, color filter 44G may transmit green light and infrared light, and color filter 44R may transmit red light and infrared light. Even if color filters 44B, 44G, and 44R transmit infrared light along with visible light of their respective colors, a visible light transmitting filter section 20 that blocks infrared light is provided in front of the visible light receiving section 40. Therefore, the light receiving elements 45B, 45G, and 45R will selectively receive only visible light of their respective colors. Color filter 44B may absorb green light and red light, color filter 44G may absorb blue light and red light, and color filter 44R may absorb blue light and green light.

[0093] As shown in Figure 6, the photodetectors 45B, 45G, and 45R may be arranged in a line in the main scanning direction (Y direction), with one of each photodetector in sequence.

[0094] On the other hand, as shown in Figure 7, the photodetectors 45B, 45G, and 45R may each be arranged in one row (a total of three rows) in the main scanning direction (Y direction). That is, the photodetectors 45B, 45G, and 45R may be arranged one by one in sequence in the sub-scanning direction (X direction).

[0095] In both cases shown in Figures 6 and 7, the visible light receiving unit 40 may have a plurality of pixels 46 arranged in a row in the main scanning direction (Y direction), and each pixel 46 may be composed of three light-receiving elements 45B, 45G, and 45R.

[0096] As shown in Figures 8 and 9, the optical sensor 1B may further include a white reference reflective section 65 provided on the inner surface (the surface on the light source 10 side) of the window material 64, and ultraviolet light receiving sections 81 and 82 that receive ultraviolet light irradiated from the light source 10 and reflected by the white reference reflective section 65.

[0097] The white reference reflective section 65 consists of a printed section of non-fluorescent white ink and white tape, and is located in an area outside the transport region, away from the transport area of ​​the banknote BN in the main scanning direction (Y direction).

[0098] In the optical paths that reflect off the white reference reflective section 65 and enter the ultraviolet light receiving sections 81 and 82, there are no visible light transmission filter section 20 or infrared light transmission filter section 30. The ultraviolet light reflected off the white reference reflective section 65 passes through the rod lens arrays 73 and 74, respectively, and is received by the ultraviolet light receiving sections 81 and 82. Therefore, the light intensity of the light source 10 can be adjusted by monitoring the output of the ultraviolet light receiving sections 81 and 82.

[0099] Furthermore, the ultraviolet light receiving section 81 is composed of multiple pixels 83 similar to each pixel 43 of the visible light receiving section 40, and each pixel 83 of the ultraviolet light receiving section 81 is composed of multiple light-receiving elements 85 similar to each light-receiving element 41 of the visible light receiving section 40. In other words, of all the pixels provided on the substrate 42 in the main scanning direction (Y direction), multiple pixels located at one end can be used as the ultraviolet light receiving section 81, and multiple pixels in the other part (effective reading area) can be used as the visible light receiving section 40.

[0100] Similarly, the ultraviolet light receiving unit 82 is composed of multiple pixels 84 similar to each pixel 53 of the infrared light receiving unit 50, and each pixel 84 of the ultraviolet light receiving unit 82 is composed of multiple light-receiving elements 86 similar to each light-receiving element 51 of the infrared light receiving unit 50. In other words, of all the pixels provided on the substrate 52 in the main scanning direction (Y direction), multiple pixels located at one end can be used as the ultraviolet light receiving unit 82, and multiple pixels in the other part (effective reading area) can be used as the infrared light receiving unit 50.

[0101] As shown in Figures 10 and 11, even when the visible light receiving unit 40 can function as a color sensor, the optical sensor 1B may further include a white reference reflective unit 65 provided on the inner surface of the window material 64 (the surface on the light source 10 side) and an ultraviolet light receiving unit 87 that receives ultraviolet light irradiated from the light source 10 and reflected by the white reference reflective unit 65. In this case as well, the amount of light from the light source 10 can be adjusted by monitoring the output of the ultraviolet light receiving unit 87.

[0102] Unlike the pixels 46 of the visible light receiving unit 40, the ultraviolet light receiving unit 87 may be composed of photodetectors 88 that do not have a color filter for spectrally separating visible light into multiple wavelengths of light (for example, blue light, green light, and red light). That is, in the case shown in Figure 10, a row of pixels 46 in which photodetectors 45B, 45G, and 45R are arranged one by one in order may be followed by a row of photodetectors 88. In the case shown in Figure 11, a row of photodetectors 45B, 45G, and 45R may be followed by three rows of photodetectors 88. (Embodiment 3) The configuration of the optical sensor according to this embodiment will be explained using Figure 12.

[0103] As shown in Figure 12, the optical sensor 1C according to this embodiment has the same configuration as the optical sensor 1B according to Embodiment 2, is configured as a line sensor, and can function as a contact image sensor.

[0104] However, in the optical sensor 1C, the visible light receiving unit 40 is positioned outside the optical path of the light emitted from the banknote BN that has been specularly reflected by the banknote BN. This prevents ultraviolet light irradiated from the light source 10 and specularly reflected by the banknote BN from traveling towards the visible light receiving unit 40. A visible light transmission filter unit 20 that transmits visible light while blocking ultraviolet light is positioned in the optical path leading to the visible light receiving unit 40. However, since the wavelength regions of visible light and ultraviolet light are adjacent, there is a possibility that some of the ultraviolet light reflected by the banknote BN may not be completely blocked by the visible light transmission filter unit 20 and may be received by the visible light receiving unit 40. In contrast, by not positioning the visible light receiving unit 40 on the optical path of the ultraviolet light specularly reflected by the banknote BN as described above, it is possible to effectively suppress the reception of ultraviolet light that could not be completely blocked by the visible light transmission filter unit 20 by the visible light receiving unit 40.

[0105] In this embodiment, the location of the infrared light receiving unit 50 can be set as appropriate, but as shown in Figure 12, the infrared light receiving unit 50 may be placed on the optical path of the light that has been specularly reflected by the banknote BN from the light emitted from the banknote BN. This is because, since the wavelength regions of visible light and ultraviolet light are far apart, the infrared light transmission filter unit 30, which transmits infrared light while blocking ultraviolet and visible light, can effectively block the ultraviolet light reflected by the banknote BN.

[0106] In this embodiment, the light source 10 and the infrared light receiving unit 50 may be arranged on both sides of the visible light receiving unit 40 in the sub-scanning direction (X direction), or the light source 10, the visible light receiving unit 40 and the infrared light receiving unit 50 may be arranged in this order in the sub-scanning direction (X direction). (Embodiment 4) The configuration of the optical sensor according to this embodiment will be explained using Figure 13.

[0107] As shown in Figure 13, the optical sensor 1D according to this embodiment has the same configuration as the optical sensor 1B according to Embodiment 2, is configured as a line sensor, and can function as a contact image sensor.

[0108] However, in the optical sensor 1D, light sources 10 are positioned on both sides of the visible light receiving unit 40 and the infrared light receiving unit 50 in the sub-scanning direction (X direction). That is, in the sub-scanning direction (X direction), the visible light receiving unit 40 and the infrared light receiving unit 50 are positioned between the pair of light sources 10, and one light source 10, the visible light receiving unit 40, the infrared light receiving unit 50, and the other light source are positioned in this order in the sub-scanning direction (X direction). (Embodiment 5) The configuration of the optical sensor according to this embodiment will be explained using Figure 14.

[0109] As shown in Figure 14, the optical sensor 1E according to this embodiment has the same configuration as the optical sensor 1B according to Embodiment 2, is configured as a line sensor, and can function as a contact image sensor.

[0110] However, in the optical sensor 1E, the light sources 10 are positioned next to the visible light receiving unit 40 and the infrared light receiving unit 50 in the sub-scanning direction (X direction). That is, one light source 10, the visible light receiving unit 40, the other light source 10, and the infrared light receiving unit 50 are arranged in this order in the sub-scanning direction (X direction). (Embodiment 6) The configuration of the optical sensor according to this embodiment will be explained using Figure 15.

[0111] As shown in Figure 15, the optical sensor 1F according to this embodiment, like the optical sensor 1A according to Embodiment 1, includes a light source 10, a visible light transmission filter section 20, an infrared light transmission filter section 30, a visible light receiving section 40, and an infrared light receiving section 50, but is configured as a point sensor and can function as a reflective sensor.

[0112] As shown in Figure 15, the optical sensor 1F comprises a rectangular parallelepiped frame 66 that houses a light source 10, a visible light transmission filter section 20, an infrared light transmission filter section 30, a visible light receiving section 40, and an infrared light receiving section 50, and a window material 67 that covers an opening provided on one side of the frame 66. The window material 67 is made of glass or the like and transmits light in the wavelength range from the ultraviolet region (e.g., UVA) to the infrared region (e.g., near-infrared).

[0113] As shown in Figure 15, in the optical sensor 1F, the visible light receiving section 40 and the infrared light receiving section 50 each have single light-receiving elements 49 and 54 arranged in a point-like manner.

[0114] In the optical sensor 1F, similar to the optical sensor 1A according to Embodiment 1, the visible light transmission filter section 20 may be composed of, for example, an ultraviolet cut filter 21 and an infrared cut filter 22 (see Figure 15), or it may be composed of a filter that transmits only visible light.

[0115] The infrared light transmission filter section 30 may be composed of, for example, a filter 31 that transmits only infrared light (see Figure 15), or it may be composed of an ultraviolet cut filter and a visible light cut filter.

[0116] Furthermore, in this embodiment, similar to the optical sensor 1A according to Embodiment 1, as shown in Figure 15, the visible light transmission filter section 20 is positioned away from the light-receiving element 49 of the visible light receiving section 40, and the infrared light transmission filter section 30 is positioned away from the light-receiving element 54 of the infrared light receiving section 50.

[0117] As shown in Figure 15, this embodiment includes a substrate 91 on which a light source 10, a visible light receiving unit 40, and an infrared light receiving unit 50 are provided.

[0118] Furthermore, the optical sensor 1F is provided with light-shielding walls 92 between the light source 10 and the visible light receiving unit 40, and between the visible light receiving unit 40 and the infrared light receiving unit 50. This prevents ultraviolet light from the light source 10 from directly entering the visible light receiving unit 40 and the infrared light receiving unit 50, prevents visible light that has passed through the visible light transmission filter unit 20 from entering the infrared light receiving unit 50, and further prevents infrared light that has passed through the infrared light transmission filter unit 30 from entering the visible light receiving unit 40. The light-shielding walls 92 are provided on the substrate 91.

[0119] As shown in Figure 15, the light-receiving element 49 of the visible light receiving unit 40 may be a light-receiving element that does not have a color filter that spectrally separates visible light into multiple wavelengths of light (for example, blue light, green light, and red light). In this case, the visible light receiving unit 40 can function as a monochrome sensor and can output the amount of fluorescence emission of visible light including blue light, green light, and red light.

[0120] On the other hand, as shown in Figure 16, the visible light receiving unit 40 may consist of three light-receiving elements 48B, 48G, and 48R, each equipped with three color filters 47B, 47G, and 47R that spectrally separate the visible light transmitted through the visible light transmission filter unit 20 into blue light, green light, and red light, respectively. In this case, the visible light receiving unit 40 can function as a color sensor and output the amount of blue fluorescence emission, the amount of green fluorescence emission, and the amount of red fluorescence emission, respectively. In this case as well, the visible light receiving unit 40 has a single light-receiving element arranged in a point-like manner.

[0121] The optical sensor 1F may further include a first optical system that collects light emitted from the banknote BN and forms an image on the light-receiving element 49 or light-receiving elements 48B, 48G, 48R of the visible light receiving unit 40, and a second optical system that collects light emitted from the banknote BN and forms an image on the light-receiving element 54 of the infrared light receiving unit 50.

[0122] As shown in Figures 17 and 18, the optical sensor 1F may further include an ultraviolet light receiving unit 93 that directly receives ultraviolet light emitted from the light source 10. This allows the light intensity of the light source 10 to be adjusted by monitoring the output of the ultraviolet light receiving unit 93.

[0123] The ultraviolet light receiving unit 93, like the visible light receiving unit 40 and the infrared light receiving unit 50, has a single light-receiving element 94 arranged in a point-like manner.

[0124] (Embodiment 7) The paper sheet processing device according to this embodiment may have, for example, the configuration shown in Figure 19. The paper sheet processing device 300 shown in Figure 19 is a small paper sheet processing device that is installed and used on a table, and comprises a paper sheet identification device (not shown in Figure 19) that performs banknote identification processing, a hopper 301 on which a plurality of banknotes to be processed are placed in a stacked state, two reject units 302 that discharge rejected banknotes such as counterfeit bills and bills of uncertain authenticity that are fed from the hopper 301 into the housing 304, an operation unit 303 for inputting instructions from the operator, four stacking units 306a to 306d for classifying and stacking banknotes whose denomination, authenticity, and condition have been identified within the housing 304, and a display unit 305 for displaying information such as the banknote identification counting results and the stacking status of each stacking unit 306a to 306d. Based on the results of the paper sheet identification device's determination of whether a banknote is genuine or damaged, genuine banknotes are stored in storage units 306a to 306c, and damaged banknotes are stored in storage unit 306d. The method for distributing banknotes to storage units 306a to 306d can be set arbitrarily.

[0125] Next, the configuration of the fluorescence detection unit of the paper sheet identification device according to this embodiment will be described using Figure 20. The fluorescence detection unit according to this embodiment may be composed of an optical sensor according to any of embodiments 2 to 6, but here we will illustrate the case in which it is equipped with a line sensor type optical sensor 1B according to embodiment 2.

[0126] As shown in Figure 20, the fluorescence detection unit 214 includes two optical sensors 1B, each positioned opposite the transport path 311 through which the banknotes BN are transported in the X direction within the XY plane. The two optical sensors 1B are located above (+Z direction) and below (-Z direction) the transport path 311, respectively.

[0127] The banknotes (BN) are transported along the transport path 311 by a transport mechanism such as the transport roller 312.

[0128] Each optical sensor 1B excites the banknotes BN being transported along the transport path 311 by irradiating them with ultraviolet light from the light source 10, and the fluorescence emitted from the banknotes BN is received by the visible light receiving unit 40 and the infrared light receiving unit 50 via the visible light transmitting filter unit 20 and the infrared light transmitting filter unit 30, respectively.

[0129] In each optical sensor 1B, the visible light receiving section 40 and the infrared light receiving section 50 each have a plurality of pixels arranged in a single row in the main scanning direction (Y direction).

[0130] In each optical sensor 1B, the visible light receiving unit 40 and the infrared light receiving unit 50 repeatedly capture images of the banknote BN being transported in the transport direction and output a signal corresponding to the amount of fluorescence emission. As a result, the fluorescence detection unit 214 acquires a fluorescence detection signal for the entire banknote BN on each main surface of the banknote BN. In other words, the fluorescence detection unit 214 can acquire fluorescence images of both main surfaces of the banknote BN.

[0131] Furthermore, since the optical sensors 1B are positioned offset in the transport direction of the banknotes BN, the optical sensor 1B located downstream in the transport direction may detect phosphorescence emitted from the banknotes BN.

[0132] Next, the configuration of the imaging unit of the paper sheet identification device according to this embodiment will be described using Figure 21. As shown in Figure 21, the imaging unit 211 comprises an upper unit 110 and a lower unit 120 arranged opposite each other. A gap is formed between the upper unit 110 and the lower unit 120, which are spaced apart in the Z direction, through which banknotes BN are transported in the X direction within the XY plane. This gap constitutes part of the transport path 311 of the paper sheet processing device according to this embodiment. The upper unit 110 and the lower unit 120 are located on the upper side (+Z direction) and lower side (-Z direction) of the transport path 311, respectively. The Y direction corresponds to the main scanning direction of the imaging unit 211, and the X direction corresponds to the sub-scanning direction of the imaging unit 211.

[0133] As shown in Figure 21, the upper unit 110 comprises two reflective light sources 111, a condensing lens 112, and a light receiving unit 113. The reflective light sources 111 sequentially irradiate the main surface (hereinafter referred to as surface A) of the banknote BN on the light receiving unit 113 side with illumination light having different wavelength bands, specifically infrared light and visible light including red, green, and blue light. The condensing lens 112 focuses the light emitted from the reflective light sources 111 and reflected from surface A of the banknote BN, and the light emitted from the transmissive light source 124 provided in the lower unit 120 and transmitted through the banknote BN. The light receiving unit 113 receives the light focused by the condensing lens 112 and converts it into an electrical signal. Then, after amplifying the electrical signal, it is A / D converted into digital data and output. Here, the light received by the light receiving unit is also called incident light, and the light emitted by the light sources is also called illumination light.

[0134] The lower unit 120 includes two reflective light sources 121 and one transmissive light source 124, a condensing lens 122, and a light receiving unit 123. The reflective light sources 121 irradiate the main surface (hereinafter referred to as the B surface) of the banknote BN on the light receiving unit 123 side with illumination light having different wavelength bands, specifically infrared light and visible light including red, green, and blue light. The condensing lens 122 emits light from the reflective light sources 121 and focuses the light reflected from the B surface of the banknote BN. The light receiving unit 123 receives the light focused by the condensing lens 122 and converts it into an electrical signal. After amplifying the electrical signal, it performs A / D conversion to digital data and then outputs it.

[0135] The light source 124 for transmission is positioned on the optical axis of the focusing lens 112 of the upper unit 110. A portion of the light emitted from the light source 124 passes through the banknote BN and is focused by the focusing lens 112 of the upper unit 110 and detected by the light receiving unit 113. The light source 124 may sequentially irradiate the B side of the banknote BN with light having different wavelength bands, or it may irradiate them simultaneously.

[0136] In this specification, light with different wavelength bands (irradiated light, incident light, etc.) refers, for example, to light with different colors in the case of visible light, and to light with wavelength bands that overlap only partially or that do not overlap in the case of infrared and ultraviolet light.

[0137] Each light source 111, 121, and 124 includes a line-shaped light guide (not shown) extending in a direction perpendicular to the plane of the paper in Figure 21 (main scanning direction (Y direction)), and a plurality of LED elements (not shown) provided at both ends (or one end) of the light guide.

[0138] Each light source 111, 121 may include an LED element that emits infrared light with a peak wavelength of 750 nm or more, an LED element that emits red light (R) with a peak wavelength of 600 nm or more and less than 750 nm, an LED element that emits green light (G) with a peak wavelength of 500 nm or more and less than 600 nm, and an LED element that emits blue light (B) with a peak wavelength of 400 nm or more and less than 500 nm. One light source 111 is placed on the upstream and downstream sides in the transport direction, flanking the condensing lens 112, and one light source 121 is placed on the upstream and downstream sides in the transport direction, flanking the condensing lens 122.

[0139] The light source 124 may include multiple LED elements that emit light having different peak wavelengths. The peak wavelength refers to the wavelength at which the light emission intensity is maximum.

[0140] The focusing lenses 112 and 122 are each composed of a rod lens array in which a plurality of rod lenses are arranged in the main scanning direction (Y direction).

[0141] Each light-receiving unit 113, 123 is equipped with a plurality of pixels arranged in a single row in the main scanning direction (Y direction).

[0142] The upper unit 110 and the lower unit 120 each repeatedly capture images of the banknote BN being transported in the transport direction and output signals corresponding to the amount of light received, thereby enabling the imaging unit 211 to acquire an image of the entire banknote BN. Specifically, the imaging unit 211 acquires a transmitted image and a reflected image of side A of the banknote BN based on the output signal of the upper unit 110, and acquires a reflected image of side B of the banknote BN based on the output signal of the lower unit 120.

[0143] Next, the configuration of the paper sheet identification device according to this embodiment will be described using Figure 22. As shown in Figure 22, the paper sheet identification device 200 according to this embodiment includes a detection unit 210, a control unit 220, and a storage unit 230.

[0144] The control unit 220 is a controller that controls each part of the paper sheet identification device 200, and is composed of a program for realizing various processes stored in the memory unit 230, a CPU (Central Processing Unit) that executes the program, and various hardware (e.g., FPGA (Field Programmable Gate Array)) controlled by the CPU. The control unit 220 controls each part of the paper sheet identification device 200 based on signals output from each part of the paper sheet identification device 200 and control signals from the control unit 220, according to the program stored in the memory unit 230. In addition, the control unit 220 has the functions of a light source control unit 221, a sensor control unit 224, an image generation unit 225, and an identification unit 223, according to the program stored in the memory unit 230.

[0145] The detection unit 210 includes a magnetic detection unit 212 and a thickness detection unit 213, in addition to the imaging unit 211 and fluorescence detection unit 214 described above, along the banknote transport path. The imaging unit 211 images the banknote as described above and outputs a color image signal and an infrared image signal. The fluorescence detection unit 214 images the banknote as described above and outputs a fluorescence image signal. The magnetic detection unit 212 includes a magnetic sensor (not shown) for measuring magnetism, and uses the magnetic sensor to detect magnetism such as magnetic ink and security threads printed on the banknote. The magnetic sensor is a magnetic line sensor in which a plurality of magnetic detection elements are arranged in a line. The thickness detection unit 213 includes a thickness detection sensor (not shown) for measuring the thickness of the banknote, and uses the thickness detection sensor to detect tape, double feeding, etc. The thickness detection sensor detects the amount of displacement of rollers facing each other across the transport path when a banknote passes, using sensors provided on each roller.

[0146] The memory unit 230 is composed of a non-volatile storage device such as a semiconductor memory or a hard disk, and stores various programs and data (for example, various reference data) for controlling the paper sheet identification device 200. The memory unit 230 also stores imaging parameters such as the wavelength band of the illumination light emitted from each light source 111, 121, and 124 during one cycle of imaging by the imaging unit 211, the timing of turning each light source 111, 121, and 124 on and off, the value of the forward current flowing through the LED elements of each light source 111, 121, and 124, and the timing of reading signals from the upper unit 110 and the lower unit 120, respectively. Similarly, the memory unit 230 also stores imaging parameters such as the timing of turning each light source 10 on and off during one cycle of imaging by the fluorescence detection unit 214, the value of the forward current flowing through the LED elements of each light source 10, and the timing of reading signals from the visible light receiving unit 40 and the infrared light receiving unit 50, respectively.

[0147] One cycle of imaging refers to an imaging pattern in which the wavelength range of the light emitted from each light source 10, 111, 121, and 124, as well as the timing of turning each light source 10, 111, 121, and 124 on and off, and reading the signals, are set. One cycle of imaging constitutes one period, and by continuously repeating this process, an image of the entire banknote is acquired.

[0148] The light source control unit 221 performs dynamic lighting control of each light source 10, 111, 121, and 124 in order to capture individual banknote images using each light source 10, 111, 121, and 124. Specifically, the light source control unit 221 controls the lighting and extinguishing of each light source 10, 111, 121, and 124 based on the timing set in the imaging parameters. This control is performed using a mechanical clock that changes according to the banknote transport speed and a system clock that is always output at a constant frequency regardless of the banknote transport speed.

[0149] The sensor control unit 224 controls the timing of reading signals from the upper unit 110 and the lower unit 120 based on the timing set in the imaging parameters, and reads signals from the upper unit 110 and the lower unit 120 in synchronization with the timing of the on and off of each light source 111, 121, and 124. The sensor control unit 224 also controls the timing of reading signals from the visible light receiving unit 40 and the infrared light receiving unit 50 based on the timing set in the imaging parameters, and reads signals from the visible light receiving unit 40 and the infrared light receiving unit 50 in synchronization with the timing of the on and off of each light source 10. This control is performed using the mechanical clock and the system clock. The sensor control unit 224 then sequentially stores the read signals, i.e., line data, in the ring buffer (line memory) of the storage unit 230.

[0150] Here, line data refers to data based on signals obtained from a single image capture by each of the upper unit 110, lower unit 120, visible light receiving unit 40, and infrared light receiving unit 50, and corresponds to one row of data in the horizontal direction (the direction perpendicular to the banknote transport direction, the Y direction) of the acquired image.

[0151] The image generation unit 225 has the function of generating images based on various signals related to banknotes acquired from the detection unit 210. Specifically, the image generation unit 225 first decomposes the data (image signals) stored in the ring buffer into data for each light irradiation and reception condition. Then, according to the characteristics of each decomposed data, the image generation unit 225 performs correction processing such as dark output cut, gain adjustment, and bright output level correction to generate various image data of banknotes and store them in the storage unit 230.

[0152] The identification unit 223 acquires the reflective image, transmitted image, and fluorescent image of the banknote BN to be identified, generated by the image generation unit 225, and identifies the banknote BN based on these images, specifically determining the denomination, authenticity, and whether it is genuine or damaged. For example, in the identification area of ​​the fluorescent image, the unit calculates the ratio of at least one of the blue fluorescence emission amount, green fluorescence emission amount, and red fluorescence emission amount (e.g., green fluorescence emission amount) to the fluorescence emission amount in the infrared region, and compares the calculated ratio with a reference ratio to determine whether the special fluorescent ink printed on the banknote BN is genuine or not. Note that this identification area may be set according to the denomination of the banknote.

[0153] Using Figure 23, another example of the configuration of the fluorescence detection unit of the paper sheet identification device according to this embodiment will be described. Specifically, an example will be given in which the fluorescence detection unit according to this embodiment is equipped with a point sensor type optical sensor 1F according to Embodiment 6.

[0154] As shown in Figure 23, the fluorescence detection unit 214 may include two optical sensors 1F, each positioned opposite the transport path 311 through which the banknotes BN are transported in the X direction within the XY plane. The two optical sensors 1F are located above (+Z direction) and below (-Z direction) the transport path 311, respectively.

[0155] Each optical sensor 1F excites the banknotes BN being transported along the transport path 311 by irradiating them with ultraviolet light from the light source 10, and the fluorescence emitted from the banknotes BN is received by the visible light receiving unit 40 and the infrared light receiving unit 50 via the visible light transmitting filter unit 20 and the infrared light transmitting filter unit 30, respectively.

[0156] Furthermore, since the optical sensors 1F are positioned offset in the direction of transport of the banknotes BN, the optical sensor 1F located downstream in the transport direction may detect phosphorescence emitted from the banknotes BN.

[0157] In this description, we have explained the case where the detection unit 210 of the paper sheet identification device 200 is equipped with an imaging unit 211, but the detection unit 210 of the paper sheet identification device 200 does not necessarily have to be equipped with an imaging unit 211.

[0158] (Embodiment 8) The configuration of the optical sensor according to this embodiment will be explained using Figure 24.

[0159] As shown in Figure 24, the optical sensor 400 according to this embodiment is a line sensor for detecting the optical characteristics of banknotes BN, and comprises a light source (not shown), a condensing lens 401 composed of a rod lens array 402, an ultraviolet cut filter 403, an ND film 404, a light receiving unit 410, a rectangular parallelepiped frame (not shown) housing these components, a window material 405 covering an opening provided on one side of the frame, and a white reference reflective unit 406 provided on the inner surface of the window material 405 (the surface on the light receiving unit 410 side). The window material 405 is made of glass or the like and transmits light in the wavelength range from the ultraviolet region (e.g., UVA) to the infrared region (e.g., near-infrared).

[0160] The light source irradiates the main surface of the banknote BN on the light-receiving section 410 side with illumination light having different wavelength bands, specifically infrared light, visible light including red, green, and blue light, and ultraviolet light for fluorescence. The light source also includes a line-shaped light guide extending in the main scanning direction (Y direction) and a plurality of LED elements provided at both ends (or one end) of the light guide. One light source is positioned on the upstream side and one on the downstream side in the transport direction, flanking the condensing lens 401.

[0161] The light source may include an LED element that emits infrared light with a peak wavelength of 750 nm or more, an LED element that emits red light (R) with a peak wavelength of 600 nm or more and less than 750 nm, an LED element that emits green light (G) with a peak wavelength of 500 nm or more and less than 600 nm, an LED element that emits blue light (B) with a peak wavelength of 400 nm or more and less than 500 nm, and an LED element that emits ultraviolet light (UV) with a peak wavelength of less than 400 nm.

[0162] The focusing lens 401 focuses the light emitted from the light source and reflected from the main surface of the banknote BN, as well as the fluorescence emitted from the main surface of the banknote BN. The focusing lens 401 is composed of a rod lens array in which a plurality of rod lenses are arranged in the main scanning direction (Y direction).

[0163] The ultraviolet cut filter 403 absorbs or reflects ultraviolet light emitted from the light source and reflected from the main surface of the banknote BN, preventing the ultraviolet light from being received by the light receiving unit 410 via the condensing lens 401. The ultraviolet cut filter 403 is provided in the transport area of ​​the banknote BN.

[0164] The ND film 404 is a neutral density filter that reduces the amount of light in the wavelength range from the ultraviolet region (e.g., UVA) to the infrared region (e.g., near-infrared) by a constant amount regardless of wavelength. It reduces the light emitted from the light source and reflected by the white reference reflective section 406. The ND film 404 may be omitted.

[0165] The white reference reflective section 406 consists of a printed section of non-fluorescent white ink and white tape, and is located in an area outside the transport region, away from the transport area of ​​the banknote BN in the main scanning direction (Y direction).

[0166] The light receiving unit 410 receives the light focused by the condensing lens 401 and converts it into an electrical signal. After amplifying the electrical signal, it performs A / D conversion to digital data and then outputs it.

[0167] The light-receiving unit 410 includes a light-receiving element 411B having a color filter that transmits blue light and infrared light, a light-receiving element 411G having a color filter that transmits green light and infrared light, a light-receiving element 411R having a color filter that transmits red light and infrared light, a light-receiving element 411C having a clear filter that transmits light in the wavelength range from the ultraviolet region (e.g., UVA) to the infrared region (e.g., near-infrared region), and a substrate 412 on which the light-receiving elements 411B, 411G, 411R, and 411C are provided.

[0168] The photodetectors 411B, 411G, 411R, and 411C are arranged one by one in a line in the main scanning direction (Y direction).

[0169] The light-receiving unit 410 has an effective reading area 413 and a light source monitoring area 414.

[0170] The effective reading area 413 faces the banknote transport area, and each pixel 415 is composed of four light-receiving elements 411B, 411G, 411R, and 411C located in the effective reading area 413. Each pixel 415 repeatedly captures an image of the banknote BN being transported in the transport direction and outputs a signal corresponding to the amount of light received, thereby enabling the optical sensor 400 to acquire an image of the entire banknote BN. Specifically, based on the output signals of each pixel 415, the optical sensor 400 acquires a reflective image and a fluorescent image of the banknote BN, and, if necessary, a transmitted image of the banknote BN.

[0171] The light source monitor area 414 faces the area outside the transport of banknotes BN, and has at least one set of four light-receiving elements 411B, 411G, 411R, and 411C.

[0172] Therefore, the optical path that is reflected by the white reference reflective section 406 and incident on each light-receiving element in the light source monitor area 414 does not have an ultraviolet cut filter 403. As a result, the ultraviolet to infrared light reflected by the white reference reflective section 406 passes through the rod lens array 402 and the ND film 404 and is received by each light-receiving element in the light source monitor area 414.

[0173] Furthermore, by monitoring the output of the three photodetectors 411B, 411G, and 411R within the light source monitor area 414, the light intensity of the LED elements emitting infrared light, blue light (B), green light (G), and red light (R) can be adjusted. Additionally, by monitoring the output of the photodetector 411C within the light source monitor area 414, the light intensity of the LED element emitting ultraviolet light (UV) can be adjusted.

[0174] According to the optical sensor 400 of this embodiment, since both the effective reading area 413 and the light source monitoring area 414 are composed of a common array of light-receiving elements (light-receiving elements 411B, 411G, 411R, 411C), it is possible to expand the effective reading area 413.

[0175] Furthermore, since there is only one type of color filter configuration for the effective reading area 413 and the light source monitor area 414, the cost of the light receiving unit 410 can be reduced. On the other hand, if the color filter configuration differs between the effective reading area 413 and the light source monitor area 414, it becomes necessary to configure the light receiving unit according to each area, which leads to an increase in the number of parts and thus an increase in cost.

[0176] Furthermore, since the light-receiving element 411C in the light source monitor area 414 receives ultraviolet light that has been attenuated via the ND film 404, the degradation of the light-receiving element 411C due to ultraviolet light may be suppressed.

[0177] (Variation 1) In the above embodiment, the case of detecting fluorescence as photoluminescence was described, but phosphorescence (photoluminescence that can be detected after the excitation light is turned off) may also be used. In that case, the phosphorescence emitted from the banknote to be identified after the ultraviolet light used as excitation light is turned off may be received by the visible light receiving unit and the infrared light receiving unit. This makes it possible to determine the authenticity of phosphorescent ink (special phosphorescent ink) that emits phosphorescence in a predetermined wavelength band including at least the visible and infrared regions after irradiation with ultraviolet light. Similar to special fluorescent ink, the phosphorescent component of this special phosphorescent ink that emits light in the infrared region is not visible to the human eye, and its optical characteristics change depending on the wavelength of the excitation light, so it can function as a highly secure security element.

[0178] Although embodiments have been described above with reference to the drawings, this disclosure is not limited to the embodiments described above. Furthermore, the configurations of each embodiment may be combined or modified as appropriate without departing from the spirit of this disclosure. [Industrial applicability]

[0179] As described above, this disclosure is a useful technique for detecting the optical features of a medium printed with photoluminescent ink with high accuracy using a simple configuration. [Explanation of Symbols]

[0180] 1A, 1B, 1C, 1D, 1E, 1F, 400: Optical sensors 10, 111, 121, 124: Light source 20: Visible light transmission filter section 21, 403: UV-cut filter 22: Infrared cut filter 30: Infrared light transmission filter section 31: Filter that transmits only infrared light 40: Visible light receiver 42, 52, 91, 412: Circuit board 41, 45B, 45G, 45R, 48B, 48G, 48R, 49, 51, 54, 85, 86, 88, 94, 411B, 411G, 411R, 411C: Photodetector 43, 46, 53, 83, 84, 415: pixels 44B, 44G, 44R, 47B, 47G, 47R: Color filters 50: Infrared light receiving unit 61: Optical path of light incident on the visible light receiving unit 62: Optical path of light incident on the infrared light receiving unit 63, 66: Frame 64, 67, 405: Window materials 65, 406: White reference reflection section 71: 1st optical system 72:Second optical system 73, 74, 402: Rod lens array 81, 82, 87, 93: Ultraviolet light receiver 92: Light-blocking wall 113, 123, 410: Light receiving section 110: Upper unit 112, 122, 401: Focusing lenses 120: Lower unit 200: Paper sheet identification device 210: Detection unit 211: Imaging Department 212: Magnetic detection unit 213: Thickness detection unit 214: Fluorescence detection unit 220: Control Unit 221: Light source control unit 223: Identification section 224: Sensor Control Unit 225: Image generation unit 230: Storage section 300: Paper sheet processing equipment 301: Hoppa 302: Rejection Department 303:Operation unit 304: Enclosure 305: Display section 306a~306d: Accumulation section 311: Conveyor Route 312: Conveyor roller 404: ND film 413: Effective read area 414: Light source monitor area BN:Banknote

Claims

1. An optical sensor for detecting the optical characteristics of a medium printed with photoluminescent ink, The aforementioned optical sensor is A light source capable of irradiating a medium with ultraviolet light, When the light source irradiates ultraviolet light, the visible light transmission filter section transmits visible light while blocking ultraviolet and infrared light from the light emitted from the medium, When the light source irradiates ultraviolet light, the infrared light transmission filter section transmits infrared light while blocking ultraviolet and visible light from the light emitted from the medium, A visible light receiving unit that receives visible light transmitted through the visible light transmission filter unit, An infrared light receiving unit that receives infrared light transmitted through the infrared light transmission filter unit, Equipped with, The visible light receiving unit and the infrared light receiving unit are provided independently of each other. An optical sensor characterized by the following features.

2. The wavelength of the light emitted from the medium and received by the visible light receiving unit and the infrared light receiving unit is longer than the wavelength of the ultraviolet light irradiated from the light source. The optical sensor according to claim 1, characterized in that it is as described above.

3. The visible light receiving unit and the infrared light receiving unit are arranged on both sides of the light source. The optical sensor according to claim 1 or 2, characterized in that it is as described above.

4. The visible light receiving unit is positioned outside the optical path of the light that has been specularly reflected by the medium from the light emitted from the medium. The optical sensor according to claim 1 or 2, characterized in that it is as described above.

5. The optical paths for light incident on the visible light receiving unit and the optical paths for light incident on the infrared light receiving unit exist separately. The optical sensor according to any one of features 1 to 4.

6. The visible light receiving unit and the infrared light receiving unit each have a plurality of light-receiving elements arranged in a line in the main scanning direction. The optical sensor according to any one of features 1 to 5.

7. The visible light receiving unit and the infrared light receiving unit are arranged on both sides of the light source in the sub-scanning direction. The optical sensor according to claim 6, characterized in that it is as described above.

8. The visible light receiving unit and the infrared light receiving unit each have a single light-receiving element arranged in a point-like manner. The optical sensor according to any one of features 1 to 5.

9. A first optical system that collects light emitted from the aforementioned medium and forms an image on the light-receiving element of the visible light receiving unit, A second optical system that collects light emitted from the aforementioned medium and forms an image on the light-receiving element of the infrared light-receiving unit, It also has The optical sensor according to any one of features 1 to 8.

10. The visible light transmission filter section is positioned at a distance from the light-receiving element of the visible light receiving section. The infrared light transmission filter is positioned away from the light-receiving element of the infrared light receiving unit. The optical sensor according to any one of features 1 to 9.

11. The visible light receiving unit has three light-receiving elements, each equipped with three color filters that spectrally separate the visible light transmitted through the visible light transmission filter into blue light, green light, and red light. The optical sensor according to any one of the features 1 to 10.

12. A paper sheet identification device characterized by comprising an optical sensor according to any one of claims 1 to 11.

13. A paper sheet processing apparatus characterized by comprising the paper sheet identification device described in claim 12.

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