Paper sheet identification device, paper sheet processing device, paper sheet identification method, and paper sheet identification program

Abstract

The present invention provides a paper sheet identification device, a paper sheet processing device, a paper sheet identification method, and a paper sheet identification program that can simultaneously and easily obtain visible and infrared data without using filter configurations that are difficult to manufacture. [Solution] A paper sheet identification device comprising: a light source capable of irradiating the paper sheets to be identified with light of a specific wavelength; a plurality of light-receiving elements each equipped with a plurality of color filters that transmit infrared light and have different visible light transmission characteristics, which receive light arriving from the paper sheets to be identified based on the light from the light source and output a light detection signal from each of the plurality of light-receiving elements; and an identification unit that calculates the amount of light of at least one color of visible light and the amount of infrared light by calculating the light quantity data based on each light quantity data based on each light detection signal output from the light-receiving unit based on the ratio of true reference data, and identifies the paper sheets based on the calculation results.

Description

Technical Field

[0001] The present disclosure relates to a paper sheet discrimination device, a paper sheet processing device, a paper sheet discrimination method, and a paper sheet discrimination program.

Background Art

[0002] Conventionally, a photoluminescence compound is known as a security element attached to paper sheets such as banknotes. The photoluminescence compound is excited by ultraviolet light or the like, and fluorescence emission or phosphorescence emission occurs. As a method for detecting those characteristics, for example, those shown in the following documents are known.

[0003] Patent Document 1 describes a device that acquires IR information in addition to visible color information (RGB). Then, by irradiating with visible light and simultaneously irradiating with light other than visible light (infrared light / ultraviolet light) during irradiation with visible light, visible color information is acquired, and by acquiring IR information as phosphorescence after all lights are turned off, visible light and color information other than visible light are acquired with a small number of lighting times.

[0004] Further, Patent Document 1 describes a second embodiment in which four light receiving elements are arranged linearly per pixel of a light receiving unit. Among the four light receiving elements, the first light receiving element is covered with a red color filter (R), the second light receiving element is covered with a green color filter (G), the third light receiving element is covered with a blue color filter (B), and the fourth light receiving element is covered with an infrared color filter (IR). This color filter (R) transmits red light, this color filter (G) transmits green light, and this color filter (B) transmits blue light, but these color filters (R), (G), (B) do not transmit ultraviolet light and infrared light. Also, the color filter (IR) used here transmits infrared light but does not transmit ultraviolet light.

[0005] Patent Document 2 describes an optical sensor for detecting light from paper sheets printed with at least one of n types of monochromatic inks, comprising: a light source; a light receiving unit equipped with first to (n-1) light receiving elements; a storage unit that stores correction values ​​based on reference data obtained by receiving light emitted by the first to n monochromatic inks individually with the light receiving unit for each type of monochromatic ink; and a correction processing unit that corrects detection data obtained by receiving light emitted from paper sheets irradiated with light from the light source with the light receiving unit, using correction values ​​based on the inverse matrix of a normalized matrix A of a predetermined n x n matrix A acquired in advance. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Patent No. 6469370 [Patent Document 2] Patent No. 7473677 [Overview of the project] [Problems that the invention aims to solve]

[0007] According to the filter configuration used in the second embodiment of Patent Document 1, it is possible to separate the visible light and infrared light arriving from the banknote 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.

[0008] According to the correction process described in Patent Document 2, it is possible to receive (detect) both visible light and infrared light arriving from banknotes together without separating them, and then separate them into signal amounts corresponding to visible light and signal amounts corresponding to infrared light. However, the correction process using the above-mentioned matrix has room for improvement in terms of ease of calculation.

[0009] This disclosure is made in view of the above-mentioned circumstances and aims to provide a paper sheet identification device, a paper sheet processing device, a paper sheet identification method, and a paper sheet identification program that can simultaneously and easily obtain visible range data and infrared range data without using a filter configuration that is difficult to manufacture. [Means for solving the problem]

[0010] To solve the above-mentioned problems and achieve the objective, (1) a paper sheet identification device according to a first aspect of the present disclosure includes a light source capable of irradiating paper sheets to be identified with light of a specific wavelength, a plurality of light-receiving elements each equipped with a plurality of color filters that transmit infrared light and have different visible light transmission characteristics, and a light-receiving unit that receives light arriving from the paper sheets to be identified based on the light from the light source with each of the plurality of light-receiving elements and outputs a light detection signal, and an identification unit that calculates the amount of light of at least one color of visible light and the amount of infrared light by calculating each light quantity data based on each light detection signal output from the light-receiving unit based on the ratio of true reference data, and identifies the paper sheets based on the calculation results.

[0011] (2) In the paper sheet identification device described in (1) above, the plurality of light-receiving elements may be a first light-receiving element having a color filter that transmits blue light and infrared light, a second light-receiving element having a color filter that transmits green light and infrared light, and a third light-receiving element having a color filter that transmits red light and infrared light, and the ratio of the true reference data may include the ratio of the output values ​​of at least two of the first light-receiving element, the second light-receiving element and the third light-receiving element.

[0012] (3) In the paper sheet identification device described in (1) or (2) above, the light of the specific wavelength irradiated by the light source may be ultraviolet light, and the light receiving unit may receive the photoluminescence of visible light and infrared light emitted from the paper sheets to be identified that have been irradiated with the ultraviolet light, and output a photoluminescence detection signal of visible light and a photoluminescence detection signal of infrared light as the light detection signal, and the identification unit may use the photoluminescence detection signal of visible light and the photoluminescence detection signal of infrared light output from the light receiving unit to identify the paper sheets to be identified.

[0013] (4) In the paper sheet identification device described in (3) above, genuine paper sheets irradiated with ultraviolet light may emit visible light photoluminescence and infrared light photoluminescence in the same region, and the plurality of light-receiving elements may consist of a first light-receiving element having a color filter that transmits blue light and infrared light, a second light-receiving element having a color filter that transmits green light and infrared light, and a third light-receiving element having a color filter that transmits red light and infrared light, and the ratio of the genuine reference data is such that the genuine paper sheets The ratio of at least two output values ​​among the output value of the first light-receiving element, the output value of the second light-receiving element, and the output value of the third light-receiving element when the light-receiving unit receives only photoluminescence equivalent to the photoluminescence of the visible light emitted by the light-receiving unit, and the ratio of at least two output values ​​among the output value of the first light-receiving element, the output value of the second light-receiving element, and the output value of the third light-receiving element when the light-receiving unit receives only photoluminescence equivalent to the photoluminescence of the infrared light emitted by the genuine paper sheets.

[0014] (5) In the paper sheet identification device described in (4) above, genuine paper sheets irradiated with ultraviolet light may emit green photoluminescence and infrared photoluminescence in the same region, and the output values ​​of the first light-receiving element, the second light-receiving element, and the third light-receiving element when the light-receiving unit receives only photoluminescence equivalent to the green photoluminescence emitted by the genuine paper sheets are defined as αBg, αGg, and αRg, respectively, and only photoluminescence equivalent to the infrared photoluminescence emitted by the genuine paper sheets is defined as Let βBir, βGir, and βRir be the output values ​​of the first, second, and third light-receiving elements when light is received by the light-receiving unit, and let X, Y, and Z be the output values ​​of the first, second, and third light-receiving elements when photoluminescence emitted from the paper sheets to be identified is received by the light-receiving unit. The identification unit may calculate G_g and IR_r based on the following formulas (I) to (III), and may use the calculated G_g and IR_r to identify the paper sheets to be identified.

[0015]

number

[0016] Here, IR_g represents the amount of infrared photoluminescence emitted from the paper sheets to be identified, among the output values ​​of the second light-receiving element when the light-receiving unit receives photoluminescence emitted from the paper sheets to be identified; G_g represents the amount of green photoluminescence emitted from the paper sheets to be identified, among the output values ​​of the second light-receiving element when the light-receiving unit receives photoluminescence emitted from the paper sheets to be identified; and IR_r represents the amount of infrared photoluminescence emitted from the paper sheets to be identified, among the output values ​​of the third light-receiving element when the light-receiving unit receives photoluminescence emitted from the paper sheets to be identified.

[0017] (6) In the paper sheet identification device described in (4) above, genuine paper sheets irradiated with ultraviolet light may emit green photoluminescence and infrared photoluminescence in the same region, and the output values ​​of the first light-receiving element, the second light-receiving element, and the third light-receiving element when the light-receiving unit receives only photoluminescence equivalent to the green photoluminescence emitted by the genuine paper sheets are defined as αBg, αGg, and αRg, respectively, and only photoluminescence equivalent to the infrared photoluminescence emitted by the genuine paper sheets is defined as Let βBir, βGir, and βRir be the output values ​​of the first, second, and third light-receiving elements when light is received by the light-receiving unit, and let X, Y, and Z be the output values ​​of the first, second, and third light-receiving elements when photoluminescence emitted from the paper sheets to be identified is received by the light-receiving unit. The identification unit may calculate G_g and IR_g based on the following formulas (I) and (II), and may use the calculated G_g and IR_g to identify the paper sheets to be identified.

[0018]

number

[0019] Here, IR_g represents the amount of infrared photoluminescence emitted from the paper sheets to be identified, among the output values ​​of the second light-receiving element when the light-receiving unit receives photoluminescence emitted from the paper sheets to be identified, and G_g represents the amount of green photoluminescence emitted from the paper sheets to be identified, among the output values ​​of the second light-receiving element when the light-receiving unit receives photoluminescence emitted from the paper sheets to be identified.

[0020] (7) In the paper sheet discrimination device according to (4) above, even if genuine paper sheets irradiated with ultraviolet light emit red photoluminescence and infrared photoluminescence in the same region, when only the photoluminescence equivalent to the red photoluminescence emitted by the genuine paper sheets is received by the light receiving unit, the output values of the first light receiving element, the output value of the second light receiving element, and the output value of the third light receiving element are respectively γBr, γGr, and γRr. When only the photoluminescence equivalent to the infrared photoluminescence emitted by the genuine paper sheets is received by the light receiving unit, the output values of the first light receiving element, the output value of the second light receiving element, and the output value of the third light receiving element are respectively βBir, βGir, and βRir. When the output values of the first light receiving element, the output value of the second light receiving element, and the output value of the third light receiving element when the photoluminescence emitted from the paper sheets to be discriminated is received by the light receiving unit are respectively X, Y, and Z, the discrimination unit may calculate R_r and IR_r based on the following formulas (IV) and (V), and may perform discrimination of the paper sheets to be discriminated using the calculated R_r and IR_r.

[0021] [Number]

[0022] Here, R_r indicates the light quantity of the red photoluminescence emitted from the paper sheets to be discriminated among the output values of the third light receiving element when the photoluminescence emitted from the paper sheets to be discriminated is received by the light receiving unit, and IR_r indicates the light quantity of the infrared photoluminescence emitted from the paper sheets to be discriminated among the output values of the third light receiving element when the photoluminescence emitted from the paper sheets to be discriminated is received by the light receiving unit.

[0023] (8) In the paper sheet identification device described in any of (3) to (7) above, the identification unit may use the visible light photoluminescence detection signal and the infrared light photoluminescence detection signal output from the light receiving unit to identify the paper sheet to be identified based on whether the visible light photoluminescence emission amount and the infrared light photoluminescence emission amount of the paper sheet to be identified are within an acceptable range with respect to a second reference data relating to the visible light photoluminescence emission amount and the infrared light photoluminescence emission amount of a genuine paper sheet.

[0024] (9) In the paper sheet identification device described in (8) above, the second reference data may include the ratio of the amount of photoluminescent emission of visible light to the amount of photoluminescent emission of infrared light, and the identification unit may calculate the ratio of the amount of photoluminescent emission of visible light to the amount of photoluminescent emission of infrared light of the paper sheet to be identified, and identify the paper sheet to be identified based on whether the ratio is within an acceptable range with respect to the ratio included in the second reference data.

[0025] (10) In the paper sheet identification device described in (8) or (9) above, the light receiving unit may receive photoluminescence of at least one color from blue, green, and red as visible light photoluminescence and output a photoluminescence detection signal of the at least one color, and the second reference data may relate to the amount of photoluminescence emission of the at least one color and the amount of photoluminescence emission of infrared light, and the identification unit may identify the paper sheet to be identified based on whether the amount of photoluminescence emission of the at least one color and the amount of photoluminescence emission of infrared light of the paper sheet to be identified are within an acceptable range with respect to the second reference data.

[0026] (11) In the paper sheet identification device described in (10) above, the light receiving unit may receive green photoluminescence as visible light photoluminescence and output a green photoluminescence detection signal, the second reference data may relate to the amount of green photoluminescence emission and the amount of infrared photoluminescence emission, and the identification unit may identify the paper sheet to be identified based on whether the amount of green photoluminescence emission and the amount of infrared photoluminescence emission of the paper sheet to be identified are within an acceptable range with respect to the second reference data.

[0027] (12) In the paper sheet identification device described in (10) above, the light receiving unit may receive red photoluminescence as visible light photoluminescence and output a red photoluminescence detection signal, the second reference data may relate to the amount of red photoluminescence emission and the amount of infrared photoluminescence emission, and the identification unit may identify the paper sheet to be identified based on whether the amount of red photoluminescence emission and the amount of infrared photoluminescence emission of the paper sheet to be identified are within an acceptable range with respect to the second reference data.

[0028] (13) In the paper sheet identification device described in (10) above, the light receiving unit may receive blue photoluminescence as visible light photoluminescence and output a blue photoluminescence detection signal, the second reference data may relate to the amount of blue photoluminescence emission and the amount of infrared photoluminescence emission, and the identification unit may identify the paper sheet to be identified based on whether the amount of blue photoluminescence emission and the amount of infrared photoluminescence emission of the paper sheet to be identified are within an acceptable range with respect to the second reference data.

[0029] (14) In the paper sheet identification device described in any of (8) to (13) above, the light receiving unit may receive near-infrared photoluminescence as infrared photoluminescence and output a near-infrared photoluminescence detection signal, the second reference data may relate to the amount of visible light photoluminescence emission and the amount of near-infrared photoluminescence emission, and the identification unit may identify the paper sheet to be identified based on whether the amount of visible light photoluminescence emission and the amount of near-infrared photoluminescence emission of the paper sheet to be identified are within an acceptable range with respect to the second reference data.

[0030] (15) Furthermore, a paper sheet processing device according to a second aspect of the present disclosure is equipped with a paper sheet identification device as described in any of (1) to (14) above.

[0031] (16) A paper sheet identification method according to a third aspect of the present disclosure comprises: a first step of irradiating the paper sheet to be identified with light of a specific wavelength from a light source; a second step of receiving light from the paper sheet to be identified based on the light from the light source with each of a plurality of light-receiving elements of a light-receiving unit and outputting a light detection signal; and a third step of identifying the paper sheet to be identified using each of the light detection signals output from the light-receiving unit, wherein each of the plurality of light-receiving elements comprises a plurality of color filters that transmit infrared light and have different visible light transmission characteristics, and in the third step, the amount of light of at least one color of visible light and the amount of infrared light are calculated by calculating each light quantity data based on each light detection signal output from the light-receiving unit based on the ratio of true reference data, and the paper sheet is identified based on the calculation result.

[0032] (17) Furthermore, a paper sheet identification program according to a fourth aspect of the present disclosure causes a paper sheet identification device to perform the following: a first process of irradiating the paper sheet to be identified with light of a specific wavelength from a light source; a second process of receiving light arriving from the paper sheet to be identified based on the light from the light source with each of a plurality of light-receiving elements of a light-receiving unit and outputting a light detection signal; and a third process of identifying the paper sheet to be identified using each of the light detection signals output from the light-receiving unit. Each of the plurality of light-receiving elements is equipped with a plurality of color filters that transmit infrared light and have different visible light transmission characteristics. In the third process, the amount of light of at least one color of visible light and the amount of infrared light are calculated by calculating the amount of light data based on each light detection signal output from the light-receiving unit based on the ratio of true reference data, and the paper sheet is identified based on the calculation results. [Effects of the Invention]

[0033] According to this disclosure, it is possible to provide a paper sheet identification device, a paper sheet processing device, a paper sheet identification method, and a paper sheet identification program that can simultaneously and easily obtain visible range data and infrared range data without using a filter configuration that is difficult to manufacture. [Brief explanation of the drawing]

[0034] [Figure 1] This is a schematic diagram illustrating an example of the configuration of a paper sheet identification device according to Embodiment 1, and is a view from an oblique direction. [Figure 2] This is a schematic perspective view illustrating an example of the configuration of the light-receiving unit of the paper sheet identification device according to Embodiment 1. [Figure 3] Figure 2 is a schematic diagram showing an example of the wavelength characteristics of the color filter in the light-receiving section. [Figure 4] This is a flowchart illustrating an example of the operation of the paper sheet identification device according to Embodiment 1. [Figure 5] This is a schematic plan view of an example of a genuine banknote, showing its appearance under visible light illumination. [Figure 6] This is a schematic plan view of an example of genuine banknote, showing its appearance under ultraviolet light irradiation. [Figure 7] This is a flowchart illustrating an example of the operation of the paper sheet identification device according to Embodiment 2. [Figure 8] This is a schematic perspective view showing the external appearance of an example of a paper sheet processing device according to Embodiment 3. [Figure 9] This is a schematic cross-sectional diagram illustrating an example of the configuration of the imaging unit of the paper sheet identification device according to Embodiment 3. [Figure 10] This is a block diagram illustrating an example of the configuration of a paper sheet identification device according to Embodiment 3. [Figure 11] This is a schematic diagram illustrating an example of the ratio of true reference data used in the calculation processing by the identification unit of the paper sheet identification device according to Embodiment 3, when receiving fluorescent ink that emits fluorescence in the green and infrared wavelength bands. [Figure 12] This is a flowchart illustrating an example of the calculation process performed by the identification unit of the paper sheet identification device according to Embodiment 3. [Figure 13] This schematic diagram illustrates an example of the green and infrared fluorescence components included in the output values ​​of each photodetector when a fluorescent ink that emits fluorescence in the green and infrared wavelength bands is received, as well as an example of the relationship between these fluorescence components and the ratio of reference data. [Figure 14] This is a schematic diagram illustrating an example of the ratio of true reference data used in the calculation processing by the identification unit of the paper sheet identification device according to Embodiment 3, when receiving fluorescent ink that emits fluorescence in the red and infrared wavelength bands. [Figure 15] This schematic diagram illustrates an example of the red and infrared fluorescence components included in the output values ​​of each photodetector when a fluorescent ink that emits fluorescence in the red and infrared wavelength bands is received, and also illustrates an example of the relationship between these fluorescence components and the ratio of reference data. [Modes for carrying out the invention]

[0035] Hereinafter, embodiments of the paper sheet identification device, paper sheet processing device, paper sheet identification method, and paper sheet identification program related to this disclosure will be described in detail with reference to the drawings. Various types of paper sheets are applicable to this disclosure, such as banknotes, checks, gift certificates, bills of exchange, business forms, securities, and card-type media, but in the following, this disclosure will be described using a device targeting banknotes as an example.

[0036] The paper sheet identification program may be pre-installed in the paper sheet identification device or paper sheet processing device, or it may be recorded on a computer-readable recording medium or provided to the operator via a network.

[0037] Thus, the paper sheet identification device and paper sheet identification and processing device relating to this disclosure may include a storage unit composed of a semiconductor memory (RAM or ROM), a hard disk, or other storage device.

[0038] Furthermore, in the following explanation, the same reference numerals are used in common across different drawings for identical parts or parts with similar functions, and repeated explanations are omitted as appropriate. In addition, mutually orthogonal XYZ coordinate systems are shown as appropriate in the drawings illustrating the structure.

[0039] (Embodiment 1) The configuration of the paper sheet identification device according to this embodiment will be explained using Figure 1.

[0040] As shown in Figure 1, the paper sheet identification device 1 according to this embodiment detects light coming from the banknote BN to be identified, and includes a light source 11 capable of irradiating the transported banknote BN with light of a specific wavelength, a light receiving unit 13 that receives light coming from the banknote BN based on the light from the light source 11 and outputs a light detection signal, and an identification unit 23 that identifies the banknote BN to be identified using the light detection signal output from the light receiving unit 13.

[0041] Here, the banknote BN to be identified may be transported in the X direction within the XY plane. The Y direction may correspond to the main scanning direction of the light receiving unit 13, and the X direction may correspond to the sub-scanning direction of the light receiving unit 13.

[0042] The light source 11 may be longer than the length of the banknote BN in the Y direction, and may illuminate the entire banknote BN in the Y direction in a straight line extending in the Y direction. In this case, the light source 11 may 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 may illuminate the banknote BN with light via the light guide.

[0043] The light-receiving unit 13 is configured to receive light arriving from the banknote BN based on light from the light source 11. For example, the light-receiving unit 13 may be configured to receive fluorescence emitted from the banknote BN while it is irradiated with light of a specific wavelength. That is, the light-receiving unit 13 may be configured to detect fluorescence from the banknote BN. Alternatively, the light-receiving unit 13 may be configured to receive reflected or transmitted light reflected or transmitted by the banknote BN while it is irradiated with light of a specific wavelength, or it may be configured to receive phosphorescence emitted from the banknote BN after it has been irradiated with light of a specific wavelength. In this case, the light-receiving unit 13 can function as a sensor sensitive to at least one wavelength band among the wavelength band of fluorescence emitted from the fluorescent ink, the wavelength band of reflected or transmitted light of the specific wavelength, and the wavelength band of phosphorescence emitted from the fluorescent ink. The light-receiving unit 13 then outputs an electrical signal (which may be a digital signal) corresponding to the amount of incident light (amount of light received). In other words, the light detection signal is an electrical signal corresponding to the amount of incident light coming from the banknote (BN).

[0044] The light-receiving unit 13 may be equipped with multiple light-receiving elements, each of which may receive light, convert it into an electrical signal corresponding to the amount of incident light, and output it.

[0045] The light-receiving unit 13 may be longer than the length of the banknote BN in the Y direction, and may receive light that has been transmitted, reflected, or emitted along the entire Y direction of the banknote BN.

[0046] The light-receiving unit 13 may output an electrical signal corresponding to the amount of incident light as image data. In this case, the light-receiving unit 13 may have multiple pixels arranged in a row in the Y direction (main scanning direction). That is, the light-receiving unit 13 may output an electrical signal corresponding to the amount of incident light in multiple channels corresponding to multiple pixels (positions in the Y direction (main scanning 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 light-receiving unit 13 may output line data as image data, which is data relating to the light received simultaneously in each channel. By repeatedly irradiating the banknote BN with light from the light source 11 and receiving the light with the light-receiving unit 13 while transporting the banknote BN in the X direction (sub-scanning direction), image data of the entire banknote BN may be output.

[0047] Thus, the light source 11 and the light receiving unit 13 may acquire an image of the entire banknote BN by continuously repeating the imaging process, with a predetermined cycle counting as one period.

[0048] In this specification, one cycle refers to a control pattern in which the timing of turning on and off the light-emitting elements in each wavelength band, and the timing of signal reading are set. One cycle of this control pattern is considered one period, and by continuously repeating this, a light detection signal may be obtained from the entire sheet of paper. One cycle may also represent a periodic control pattern related to turning on, off, and receiving light set to acquire reflected and / or transmitted light images of the sheet of paper.

[0049] A reflected light image is an image based on light reflected by paper sheets that are illuminated from a light source positioned on the same side as the light-receiving unit. A transmitted light image is an image based on light transmitted through paper sheets that are illuminated from a light source positioned on the opposite side of the light-receiving unit. Therefore, reflected light images and transmitted light images are distinct from fluorescent or phosphorescent images, which are based on fluorescence or phosphorescence emitted from the paper sheets.

[0050] The image data acquired by the light-receiving unit 13 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 light-receiving unit 13 corresponding to its position in the Y direction and the line (row) corresponding to its position in the X direction. The line (row) is a number sequentially assigned to the line data output sequentially by the light-receiving unit 13.

[0051] Furthermore, the light-receiving unit 13 may receive light of multiple wavelength bands arriving from the banknote BN and output electrical signals (photodetection signals) for each of the multiple wavelength bands. In this case, each pixel may be equipped with multiple light-receiving elements that selectively receive light of different wavelength bands.

[0052] Multiple wavelength bands that the light-receiving unit 13 can selectively receive include red (R), green (G), blue (B), infrared (IR), and others.

[0053] 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.

[0054] In this embodiment, as shown in Figures 2 and 3, the light receiving unit 13 has a plurality of light receiving elements 31, each equipped with a plurality of color filters 32 that transmit infrared light and have different visible light transmission characteristics. Based on the light from the light source 11, each of the plurality of light receiving elements 31 receives the light coming from the banknote BN to be identified and outputs a light detection signal. In this way, the light receiving unit 13 may receive the visible light and infrared light emitted from the banknote BN together without separating them and output a light detection signal that includes a signal value corresponding to the total amount of light of both components.

[0055] A light-receiving unit 13 equipped with such a filter configuration (color filter 32) is easier to manufacture than a light-receiving unit equipped with a conventional filter configuration (for example, the filter configuration used in the second embodiment of Patent Document 1). Furthermore, as will be described in detail later, it is possible to calculate the amount of light for each predetermined wavelength band in the visible range detected by each light-receiving element, specifically, for example, the amount of blue light, the amount of green light, and the amount of red light, as well as the amount of infrared light, through a relatively simple calculation process using the output values ​​(light intensity data) of each light-receiving element that simultaneously receive light arriving from the banknote BN, and reference data.Therefore, according to this embodiment, it is possible to obtain visible range data and infrared range data simultaneously and easily without using a filter configuration that is difficult to manufacture.

[0056] Note that "light intensity" is a value that fluctuates depending on the amount of light incident on the light-receiving part (amount of light received).

[0057] More specifically, as shown in Figures 2 and 3, the light-receiving unit 13 may include a first light-receiving element 31B having a color filter 32B that transmits blue light and infrared light, a second light-receiving element 31G having a color filter 32G that transmits green light and infrared light, and a third light-receiving element 31R having a color filter 32R that transmits red light and infrared light. The first light-receiving element 31B, the second light-receiving element 31G, and the third light-receiving element 31R each receive infrared light along with their corresponding visible light. Furthermore, the color filter 32B absorbs green light and red light, the color filter 32G absorbs blue light and red light, and the color filter 32R absorbs blue light and green light.

[0058] As shown in Figure 2, the light-receiving unit 13 may include a plurality of pixels 30 arranged in a row in the main scanning direction D1 (the direction perpendicular to the transport direction of the banknote BN, the Y direction), and each pixel 30 may include one first light-receiving element (image sensor) 31B, one second light-receiving element (image sensor) 31G, and one third light-receiving element (image sensor) 31R, and the first light-receiving element 31B, the second light-receiving element 31G, and the third light-receiving element 31R may be arranged in this order in a row in the main scanning direction D1.

[0059] Here, a light-receiving element (image sensor) means an element that detects (converts into an electrical signal) the intensity of light in a predetermined wavelength band, and may be configured to include a photodetector such as a photodiode, and a color filter (color resist) provided on the light-receiving surface of the photodetector that suppresses the transmission of light in wavelength bands other than the predetermined wavelength band to be detected (for example, the blue and infrared wavelength bands) (for example, the green and red wavelength bands).

[0060] As shown in Figure 2, the first light-receiving element 31B may include a photodetector 33 and a color filter 32B, the second light-receiving element 31G may include a photodetector 33 and a color filter 32G, and the third light-receiving element 31R may include a photodetector 33 and a color filter 32R.

[0061] Next, we will explain the calculation process performed by the identification unit 23 using the output values ​​(light intensity data) of each light-receiving element.

[0062] The identification unit 23 calculates the light intensity of at least one color of visible light and the infrared light intensity based on the ratio of true reference data for each light intensity data based on each light detection signal output from the light receiving unit 13, and identifies the banknote BN to be identified based on the calculation results. By using a reference ratio in this way, the output values ​​of each light receiving element 31, which receives both visible and infrared light emitted from the banknote BN without separation, can be separated into the light intensity (signal amount) corresponding to the visible light transmitted by the color filter and the light intensity (signal amount) corresponding to the infrared light. Furthermore, the calculation process using the ratio of true reference data can be performed more easily than the calculation process using a matrix described in Patent Document 2.

[0063] The "reference data" referenced by the identification unit 23 may be information defining a standard for the amount of light of at least one color of visible light and the amount of infrared light that is acceptable (authentic) for genuine banknotes. The ratio of authentic reference data may include, for example, the ratio of the output values ​​of multiple photodetectors 31 when the photodetector 13 receives light components corresponding to the visible region in the spectrum measured from a genuine banknote irradiated with light of a specific wavelength, and the ratio of the output values ​​of multiple photodetectors 31 when the photodetector 13 receives light components corresponding to the infrared region in the spectrum measured from a genuine banknote irradiated with light of a specific wavelength. These output values ​​are not limited to those actually received (detected) by the photodetector 13 as described above, but may also be values ​​calculated (estimated) from a spectrum covering the visible to infrared regions measured from a genuine banknote irradiated with light of a specific wavelength. In the latter case, for example, it is possible to extract (separate) only the spectral components contained in the visible range from the measured spectrum, and by multiplying the extracted spectral components by the sensitivity characteristics of the multiple photodetectors 31, it is possible to calculate (estimate) the output values ​​of the multiple photodetectors 31 when the photodetector 13 receives light components corresponding to the spectral components contained in the visible range. Similarly, in that case, for example, it is possible to extract (separate) only the spectral components contained in the infrared range from the measured spectrum, and by multiplying the extracted spectral components by the sensitivity characteristics of the multiple photodetectors 31, it is possible to calculate (estimate) the output values ​​of the multiple photodetectors 31 when the photodetector 13 receives light components corresponding to the spectral components contained in the infrared range.

[0064] Furthermore, the "at least one color of visible light" calculated by the identification unit 23 corresponds to at least one color of visible light among the multiple colors transmitted through each of the multiple color filters 32. That is, if the multiple color filters 32 consist of a color filter 32B that transmits blue light and infrared light, a color filter 32G that transmits green light and infrared light, and a color filter 32R that transmits red light and infrared light, then "at least one color of visible light" corresponds to at least one color of blue light, green light, and red light.

[0065] As described above, if the multiple light-receiving elements 31 consist of a first light-receiving element 31B having a color filter 32B that transmits blue light and infrared light, a second light-receiving element 31G having a color filter 32G that transmits green light and infrared light, and a third light-receiving element 31R having a color filter 32R that transmits red light and infrared light, the ratio of the true reference data may include the ratio of at least two of the output values ​​of the first light-receiving element 31B, the second light-receiving element 31G, and the third light-receiving element 31R. That is, if the output values ​​of the first light-receiving element 31B, the second light-receiving element 31G, and the third light-receiving element 31R are a, b, and c, respectively, the ratio of the true reference data may include at least one of the ratios a:b, b:c, a:c, and a:b:c.

[0066] The ratio of the true reference data may be a ratio, as in a:b above, a ratio value, such as a / b, or their percentages.

[0067] Next, the operation of the paper sheet identification device 1 according to this embodiment will be explained using Figure 4.

[0068] As shown in Figure 4, first, the light source 11 irradiates the banknote BN to be identified with light of at least a specific wavelength (step S11).

[0069] Next, the light receiving unit 13 receives light arriving from the banknote BN to be identified, which is irradiated with light of a specific wavelength, and outputs a light detection signal (step S12).

[0070] The light-receiving unit 13 has multiple light-receiving elements 31, each equipped with multiple color filters 32 that transmit infrared light and have different visible light transmission characteristics. The light-receiving unit 13 receives light coming from the banknote BN to be identified based on the light from the light source 11 with each light-receiving element 31 and outputs a light detection signal from each light-receiving element 31 (see Figures 2 and 3).

[0071] Subsequently, the identification unit 23 identifies the banknote BN to be identified using the light detection signal output from the light receiving unit 13 (step S13), and the operation of the paper sheet identification device 1 ends. Here, the identification unit 23 calculates the amount of light of at least one color of visible light and the amount of infrared light by calculating the light intensity data (output value of each light receiving element 31) based on each light detection signal output from the light receiving unit 13 based on the ratio of true reference data, and identifies the banknote BN to be identified based on the calculation results.

[0072] The identification unit 23 may also function by executing a corresponding program by the control unit, which will be described later.

[0073] (Embodiment 2) This embodiment describes the case in which photoluminescence emitted from the banknote BN to be identified is detected.

[0074] In this specification, photoluminescence is a concept that encompasses fluorescence and phosphorescence, but below, we will explain the case where fluorescence (photoluminescence that can be detected during excitation light irradiation) is detected as photoluminescence. That is, below we will explain the cases where "photoluminescence," "photoluminescence detection signal," "photoluminescence emission amount," "photoluminescence ink," "visible photoluminescence ink," and "infrared photoluminescence ink" are "fluorescence," "fluorescence detection signal," "fluorescence emission amount," "fluorescent ink," "visible fluorescent ink," and "infrared fluorescent ink," respectively.

[0075] First, in this embodiment, we will describe a genuine banknote that can be compared with the banknote to be identified. As shown in Figures 5 and 6, a genuine banknote has fluorescent ink, which is the subject of authenticity determination, printed in a predetermined area R.

[0076] This fluorescent ink contains one or more photoluminescent compounds, for example, two or more, and emits fluorescence in a predetermined wavelength band including at least the visible and infrared regions while irradiated with ultraviolet light as excitation light. The fluorescence of this fluorescent ink may have peak wavelengths in the visible and infrared regions, respectively. Hereinafter, this fluorescent ink may be referred to as special fluorescent ink.

[0077] On the other hand, this special fluorescent ink emits almost no light when irradiated with 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 (see Figure 5). Furthermore, when the special fluorescent ink is irradiated with ultraviolet light, the fluorescent components that emit light in the visible range can be seen by the human eye (see Figure 6), but even then, the fluorescent components that emit light in the infrared range are invisible to the human eye. Therefore, this special fluorescent ink can function as a highly secure security element.

[0078] The printed area of ​​the special fluorescent ink may, for example, be printed with an ink containing a mixture of a photoluminescent compound that fluoresces in the visible range and a photoluminescent compound that fluoresces in the infrared range, or an ink containing a photoluminescent compound that fluoresces in the visible range and an ink containing a photoluminescent compound that fluoresces in the infrared range may be applied in layers.

[0079] The paper sheet identification device according to this embodiment detects fluorescence emitted from the banknote BN to be identified, and, like the paper sheet identification device 1 according to Embodiment 1, comprises a light source 11, a light receiving unit 13, and an identification unit 23 (see Figure 1). However, the light of a specific wavelength emitted by the light source 11 is ultraviolet light, and the light receiving unit 13 receives visible light fluorescence and infrared light fluorescence emitted from the banknote BN to be identified that has been irradiated with ultraviolet light, and outputs a visible light fluorescence detection signal and an infrared light fluorescence detection signal as photodetection signals, and the identification unit 23 uses the visible light fluorescence detection signal and the infrared light fluorescence detection signal output from the light receiving unit 13 to identify the banknote BN to be identified. According to the paper sheet identification device according to this embodiment, the banknote BN to be identified can be identified based on the visible light fluorescence and infrared light fluorescence emitted from the banknote BN to be identified.

[0080] In this embodiment, as described above, a genuine banknote irradiated with ultraviolet light may emit fluorescence of both visible light and infrared light in the same region R (see Figure 6), and the multiple photodetectors 31 may consist of a first photodetector 31B having a color filter 32B that transmits blue light and infrared light, a second photodetector 31G having a color filter 32G that transmits green light and infrared light, and a third photodetector 31R having a color filter 32R that transmits red light and infrared light (see Figures 2 and 3). Furthermore, the ratio of the true reference data may include the ratio of at least two output values ​​among the output value a1 of the first light-receiving element 31B, the output value b2 of the second light-receiving element 31G, and the output value c3 of the third light-receiving element 31R when the light-receiving unit 13 receives only fluorescence equivalent to the visible light fluorescence emitted by a true banknote (for example, at least one of a1:b1, b1:c1, a1:c1, a1:b1:c1), and the ratio of at least two output values ​​among the output value a2 of the first light-receiving element 31B, the output value b2 of the second light-receiving element 31G, and the output value c2 of the third light-receiving element 31R when the light-receiving unit 13 receives only fluorescence equivalent to the infrared light fluorescence emitted by a true banknote (for example, at least one of a2:b2, b2:c2, a2:c2, a2:b2:c2). This enables highly accurate determination of the authenticity of special fluorescent inks.

[0081] Here, "receiving only fluorescence equivalent to the visible light fluorescence emitted by genuine banknotes" means receiving only the fluorescence components corresponding to the spectral components included in the visible range from the fluorescence spectrum measured from genuine banknotes (genuine special fluorescent ink) irradiated with ultraviolet light. For example, the light receiving unit 13 may receive fluorescence emitted by a visible fluorescent ink that emits fluorescence with a spectrum approximating the spectral components included in the visible range from the fluorescence spectrum measured from genuine special fluorescent ink. More specifically, for example, if the genuine special fluorescent ink contains a mixture of a photoluminescent compound that emits fluorescence in the visible range and a photoluminescent compound that emits fluorescence in the infrared range, ultraviolet light may be irradiated onto a reference pattern printed with only the photoluminescent compound that emits fluorescence in the visible range to cause emission, and the light receiving unit 13 may receive this fluorescence.

[0082] Similarly, "receiving only fluorescence equivalent to the infrared fluorescence emitted by genuine banknotes" means receiving only the fluorescence components corresponding to the spectral components included in the infrared region of the fluorescence spectrum measured from genuine banknotes (genuine special fluorescent ink) irradiated with ultraviolet light. For example, the fluorescence emitted by infrared fluorescent ink that fluoresces with a spectrum approximating the spectral components included in the infrared region of the fluorescence spectrum measured from genuine special fluorescent ink may be received by the light receiving unit 13 alone. More specifically, for example, if the genuine special fluorescent ink contains a mixture of a photoluminescent compound that fluoresces in the visible region and a photoluminescent compound that fluoresces in the infrared region, ultraviolet light may be irradiated onto a reference pattern printed with only the photoluminescent compound that fluoresces in the infrared region to cause emission, and the fluorescence may be received by the light receiving unit 13.

[0083] A genuine banknote irradiated with ultraviolet light may emit green fluorescence and infrared fluorescence in the same region R (see Figure 6). In this case, the output values ​​of the first light-receiving element 31B, the second light-receiving element 31G, and the third light-receiving element 31R when the light-receiving unit 13 receives only fluorescence equivalent to the green fluorescence emitted by a genuine banknote are defined as αBg, αGg, and αRg, respectively. The output values ​​of the first light-receiving element 31B, the second light-receiving element 31G, and the third light-receiving element 31R when the light-receiving unit 13 receives only fluorescence equivalent to the infrared fluorescence emitted by a genuine banknote are defined as follows: Let βBir, βGir, and βRir be denoted respectively. When the light receiving unit 13 receives fluorescence emitted from the banknote BN to be identified, the output values ​​of the first light receiving element 31B, the second light receiving element 31G, and the third light receiving element 31R are denoted as X, Y, and Z, respectively. The identification unit 23 may then calculate G_g and IR_r based on the following formulas (I) to (III), and use the calculated G_g and IR_r to identify the banknote BN to be identified. This enables highly accurate determination of the authenticity of special fluorescent inks that emit fluorescence in the green and infrared wavelength bands.

[0084]

number

[0085] Here, IR_g represents the amount of infrared fluorescence emitted from the banknote BN to be identified, among the output values ​​of the second photodetector 31G when the photodetector 13 receives fluorescence emitted from the banknote BN to be identified; G_g represents the amount of green fluorescence emitted from the banknote BN to be identified, among the output values ​​of the second photodetector 31G when the photodetector 13 receives fluorescence emitted from the banknote BN to be identified; and IR_r represents the amount of infrared fluorescence emitted from the banknote BN to be identified, among the output values ​​of the third photodetector 31R when the photodetector 13 receives fluorescence emitted from the banknote BN to be identified.

[0086] If a genuine banknote irradiated with ultraviolet light emits green fluorescence and infrared fluorescence in the same region R, then, as described above, the output values ​​of the first light-receiving element 31B, the second light-receiving element 31G, and the third light-receiving element 31R when the light-receiving unit 13 receives only fluorescence equivalent to the green fluorescence emitted by the genuine banknote are set to αBg, αGg, and αRg, respectively, and the output values ​​of the first light-receiving element 31B and the second light-receiving element 31R when the light-receiving unit 13 receives only fluorescence equivalent to the infrared fluorescence emitted by the genuine banknote are set to αBg, αGg, and αRg, respectively. Let the output values ​​of element 31G and the third light-receiving element 31R be βBir, βGir, and βRir, respectively. When the light-receiving unit 13 receives fluorescence emitted from the banknote BN to be identified, the output values ​​of the first light-receiving element 31B, the second light-receiving element 31G, and the third light-receiving element 31R be X, Y, and Z, respectively, the identification unit 23 may calculate G_g and IR_g based on the following formulas (I) and (II), and use the calculated G_g and IR_g to identify the banknote BN to be identified. This also enables highly accurate determination of the authenticity of special fluorescent inks that emit fluorescence in the green and infrared wavelength bands.

[0087]

number

[0088] Here, IR_g represents the amount of infrared fluorescence emitted from the banknote BN to be identified, among the output values ​​of the second photodetector 31G when the photodetector 13 receives fluorescence emitted from the banknote BN to be identified, and G_g represents the amount of green fluorescence emitted from the banknote BN to be identified, among the output values ​​of the second photodetector 31G when the photodetector 13 receives fluorescence emitted from the banknote BN to be identified.

[0089] A genuine banknote irradiated with ultraviolet light may emit red fluorescence and infrared fluorescence in the same region R (see Figure 6). In this case, the output values ​​of the first light-receiving element 31B, the second light-receiving element 31G, and the third light-receiving element 31R when the light-receiving unit 13 receives only fluorescence equivalent to the red fluorescence emitted by the genuine banknote are defined as γBr, γGr, and γRr, respectively. The output values ​​of the first light-receiving element 31B, the second light-receiving element 31G, and the third light-receiving element 31R when the light-receiving unit 13 receives only fluorescence equivalent to the infrared fluorescence emitted by the genuine banknote are defined as follows: Let βBir, βGir, and βRir be denoted respectively. When the light receiving unit 13 receives fluorescence emitted from the banknote BN to be identified, the output values ​​of the first light receiving element 31B, the second light receiving element 31G, and the third light receiving element 31R are denoted as X, Y, and Z, respectively. The identification unit 23 may then calculate R_r and IR_r based on the following formulas (IV) and (V), and use the calculated R_r and IR_r to identify the banknote BN to be identified. This enables highly accurate determination of the authenticity of special fluorescent inks that emit fluorescence in the red and infrared wavelength bands.

[0090]

number

[0091] Here, R_r represents the amount of red fluorescence emitted from the banknote BN to be identified, among the output values ​​of the third light-receiving element 31R when the light-receiving unit 13 receives fluorescence emitted from the banknote BN to be identified, and IR_r represents the amount of infrared fluorescence emitted from the banknote BN to be identified, among the output values ​​of the third light-receiving element 31R when the light-receiving unit 13 receives fluorescence emitted from the banknote BN to be identified.

[0092] Here, "receiving only fluorescence equivalent to the green (or red) fluorescence emitted by genuine banknotes" means receiving only the fluorescence components corresponding to the spectral components included in the green (or red) wavelength band of the fluorescence spectrum measured from genuine banknotes (genuine special fluorescent ink) irradiated with ultraviolet light. For example, the fluorescence emitted by green (or red) fluorescent ink that fluoresces with a spectrum approximating the spectral components included in the green (or red) wavelength band of the fluorescence spectrum measured from genuine special fluorescent ink may be received by the light-receiving unit 13 alone. More specifically, for example, if the genuine special fluorescent ink contains a mixture of a photoluminescent compound that fluoresces in the green (or red) wavelength band and a photoluminescent compound that fluoresces in the infrared region, ultraviolet light may be irradiated onto a reference pattern printed with only the photoluminescent compound that fluoresces in the green (or red) wavelength band to cause emission, and the fluorescence may be received by the light-receiving unit 13.

[0093] Furthermore, "receiving only fluorescence equivalent to that emitted by genuine banknotes" means, as described above, that the device receives only the fluorescence components corresponding to the spectral components included in the infrared region of the fluorescence spectrum measured from genuine banknotes (genuine special fluorescent ink) irradiated with ultraviolet light.

[0094] The identification unit 23 may identify the banknote BN to be identified based on the light intensity itself calculated by the above formula. Alternatively, the identification unit 23 may identify the banknote BN to be identified based on the ratio of the light intensity calculated by the above formula (for example, the ratio of the light intensity of green fluorescence to the light intensity of infrared fluorescence, or the ratio of the light intensity of red fluorescence to the light intensity of infrared fluorescence).

[0095] Thus, the identification unit 23 may use the calculated light intensity itself to identify the banknote BN, or it may use an evaluation value (for example, a ratio or sum) based on the calculated light intensity to identify the banknote BN.

[0096] In either case, the identification unit 23 may determine the authenticity and presence or absence of fluorescent ink on a banknote BN, for example, by whether the calculated light intensity or its evaluation value is within an acceptable range relative to predetermined reference data.

[0097] In this context, the "predetermined reference data" referenced by the identification unit 23 is information that defines a standard (e.g., a threshold) for the amount of light that is acceptable to a genuine banknote, and may include, for example, the upper and lower limits of the amount of light detected from a genuine banknote or its evaluation value. Furthermore, determining whether a certain amount of light or its evaluation value is within the acceptable range for this reference data may mean determining whether that amount of light or its evaluation value is between the upper and lower limits of the amount of light or its evaluation value defined by this reference data.

[0098] Furthermore, the identification unit 23 may use the visible light fluorescence detection signal and infrared light fluorescence detection signal output from the light receiving unit 13 to identify the banknote BN to be identified by determining whether the visible light fluorescence emission amount and infrared light fluorescence emission amount of the banknote BN to be identified are within an acceptable range with respect to a second reference data relating to the visible light fluorescence emission amount and infrared light fluorescence emission amount of a genuine banknote. This also makes it possible to determine the authenticity of a special fluorescent ink that emits fluorescence in a predetermined wavelength band including at least the visible and infrared regions. In other words, the paper sheet identification device according to this embodiment can mechanically identify banknotes with high security using photoluminescence compounds. Thus, the identification unit 23 may also perform the determination of the authenticity of the banknote BN to be identified.

[0099] Here, the visible light fluorescence emission amount and infrared light fluorescence emission amount of the banknote BN to be identified may correspond to the visible light light amount (green fluorescence light amount or red fluorescence light amount) and the infrared fluorescence light amount, respectively, calculated by the above formula. In other words, the visible light fluorescence emission amount and infrared light fluorescence emission amount of the banknote BN to be identified can be calculated by a calculation process using the output values ​​of the first to third photodetectors when fluorescence emitted from the banknote BN to be identified is received. To put it another way, in this embodiment, the identification unit 23 calculates the visible light fluorescence emission amount and infrared light fluorescence emission amount of the banknote BN to be identified by processing the fluorescence detection signal obtained by receiving fluorescence emitted from the banknote BN to be identified, which has been irradiated with ultraviolet light, with the photodetector 13, and identifies the banknote BN to be identified based on whether the calculated visible light fluorescence emission amount and infrared light fluorescence emission amount are within an acceptable range with respect to the second reference data.

[0100] Note that "fluorescence emission amount" is a value that indicates the intensity (brightness) of the fluorescence in question.

[0101] In this embodiment, the light source 11 irradiates the banknote BN with ultraviolet light as excitation light. The light source 11 may be located on the same side as the light receiving unit 13 with respect to the banknote BN.

[0102] In this embodiment, the light-receiving unit 13 is configured to receive fluorescence emitted from the special fluorescent ink of the banknote BN to be identified while ultraviolet light is irradiated onto it. That is, the light-receiving unit 13 is configured to detect both the visible-range fluorescence component and the infrared-range fluorescence component emitted from the special fluorescent ink. In this case, the light-receiving unit 13 can function as a sensor that is sensitive to at least the wavelength range (visible and infrared) of the fluorescence emitted from the special fluorescent ink. The fluorescence detection signal is an electrical signal corresponding to the amount of incident light of fluorescence emitted from the banknote BN during the period of ultraviolet light illumination.

[0103] In this embodiment, the “second reference data” that can be referenced by the identification unit 23 is information that defines a standard (e.g., a threshold) for the amount of visible light fluorescence emission and infrared light fluorescence emission that is acceptable for a genuine banknote, and may include, for example, upper and lower limits for the amount of visible light fluorescence emission and infrared light fluorescence emission, respectively. Furthermore, determining whether a certain amount of fluorescence emission is within the acceptable range for the second reference data may mean determining whether that amount of fluorescence emission is between the upper and lower limits of the fluorescence emission amount defined by the second reference data.

[0104] The second reference data may include the ratio of the visible light fluorescence emission amount to the infrared light fluorescence emission amount of a genuine banknote. In this case, the identification unit 23 may calculate the ratio of the visible light fluorescence emission amount to the infrared light fluorescence emission amount of the banknote to be identified and identify the banknote to be identified based on whether or not that ratio is within an acceptable range with respect to the ratio included in the second reference data. This makes it possible to determine the authenticity of the special fluorescent ink with higher accuracy.

[0105] Hereinafter, the ratio of visible light fluorescence emission to infrared light fluorescence emission may simply be referred to as the fluorescence emission ratio. The fluorescence emission ratio may be calculated by dividing the visible light fluorescence emission by the infrared light fluorescence emission, or vice versa, or as a percentage of each.

[0106] When using fluorescence emission ratio, the second reference data may include upper and lower limits for the fluorescence emission ratio that is acceptable for a genuine banknote. The identification unit 23 may also determine whether the fluorescence emission ratio of the banknote to be identified falls between the upper and lower limits of the fluorescence emission ratio defined by the second reference data.

[0107] The special fluorescent ink may have a fluorescence spectrum that has a peak in at least one of the blue wavelength band, the green wavelength band, and the red wavelength band, or it may have a peak in only one of the blue, green, or red wavelength bands in the visible range.

[0108] Furthermore, the light-receiving unit 13 receives fluorescence of at least one of blue, green, and red as visible light fluorescence and outputs a fluorescence detection signal of the at least one color. The second reference data relates to the amount of fluorescence emission of the at least one color and the amount of fluorescence emission of infrared light. The identification unit 23 may identify the banknote to be identified based on whether the amount of fluorescence emission of the at least one color and the amount of fluorescence emission of infrared light of the banknote to be identified are within an acceptable range relative to the second reference data. This makes it possible to determine the authenticity of special fluorescent inks that have peaks in at least one wavelength band among the blue wavelength band, the green wavelength band, and the red wavelength band in their fluorescence spectrum.

[0109] More specifically, the light receiving unit 13 receives green fluorescence as visible light fluorescence and outputs a green fluorescence detection signal, the second reference data relates to the amount of green fluorescence emission and the amount of infrared fluorescence emission, and the identification unit 23 may identify the banknote to be identified based on whether the amount of green fluorescence emission and the amount of infrared fluorescence emission of the banknote to be identified are within an acceptable range relative to the second reference data.

[0110] Furthermore, the light receiving unit 13 receives red fluorescence as visible light fluorescence and outputs a red fluorescence detection signal, the second reference data relates to the amount of red fluorescence emission and the amount of infrared fluorescence emission, and the identification unit 23 may identify the banknote to be identified based on whether the amount of red fluorescence emission and the amount of infrared fluorescence emission of the banknote to be identified are within an acceptable range relative to the second reference data.

[0111] Furthermore, the light-receiving unit 13 receives blue fluorescence as visible light fluorescence and outputs a blue fluorescence detection signal, and the second reference data relates to the amount of blue fluorescence emission and the amount of infrared fluorescence emission. The identification unit 23 may identify the banknote to be identified based on whether the amount of blue fluorescence emission and the amount of infrared fluorescence emission of the banknote to be identified are within an acceptable range relative to the second reference data.

[0112] The special fluorescent ink may have a fluorescence spectrum that peaks in the infrared region or in the near-infrared region.

[0113] Thus, the light-receiving unit 13 receives near-infrared fluorescence as infrared fluorescence and outputs a near-infrared fluorescence detection signal. The second reference data relates to the visible light fluorescence emission amount and the near-infrared fluorescence emission amount. The identification unit 23 may identify the banknote to be identified based on whether the visible light fluorescence emission amount and the near-infrared fluorescence emission amount of the banknote to be identified are within an acceptable range relative to the second reference data. This makes it possible to determine the authenticity of special fluorescent inks that have a peak in the near-infrared region in their fluorescence spectrum.

[0114] Next, the operation of the paper sheet identification device according to this embodiment will be explained using Figure 7.

[0115] As shown in Figure 7, first, the light source 11 irradiates the banknote BN to be identified with at least ultraviolet light (step S21).

[0116] Next, the light-receiving unit 13 receives visible light fluorescence and infrared light fluorescence emitted from the banknote BN to be identified, which has been irradiated with ultraviolet light, and outputs a visible light fluorescence detection signal and an infrared light fluorescence detection signal as photodetection signals (step S22).

[0117] The light-receiving unit 13, as in Embodiment 1, has a plurality of light-receiving elements 31, each equipped with a plurality of color filters 32 that transmit infrared light and have different visible light transmission characteristics (see Figures 2 and 3). Based on ultraviolet light from the light source 11, the light-receiving elements 31 receive visible light fluorescence and infrared light fluorescence arriving from the banknote BN to be identified, and output visible light fluorescence detection signals and infrared light fluorescence detection signals, respectively.

[0118] Subsequently, the identification unit 23 identifies the banknote BN to be identified using the visible light fluorescence detection signal and the infrared light fluorescence detection signal output from the light receiving unit 13 (step S23), and the operation of the paper sheet identification device according to this embodiment ends.

[0119] In this embodiment as well, the identification unit 23 may function by executing a corresponding program by the control unit, which will be described later.

[0120] (Embodiment 3) The paper sheet processing device according to this embodiment may have, for example, the configuration shown in Figure 8. The paper sheet processing device 300 shown in Figure 8 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 8) 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.

[0121] Next, the configuration of the imaging unit, which is the main part of the paper sheet identification device according to this embodiment, will be described using Figure 9. As shown in Figure 9, the imaging unit 211 comprises an upper unit 110 and a lower unit 120 that are arranged facing 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 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, 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.

[0122] As shown in Figure 9, the upper unit 110 includes two reflective light sources 111, a condensing lens 112, a light receiving unit 113, and a UV-cut film 115. 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 light having different wavelength bands, specifically infrared light, white light including red, green, and blue light, and ultraviolet light as excitation light for fluorescence. The condensing lens 112 collects the light emitted from the reflective light sources 111 and reflected from surface A of the banknote BN, the light emitted from the transmitting light source 124 provided in the lower unit 120 and transmitted through the banknote BN, and the fluorescence emitted from surface A of the banknote BN. The light receiving unit 113 receives the light collected by the condensing lens 112 and converts it into an electrical signal. After amplifying the electrical signal, it performs A / D conversion to digital data and outputs it. Here, the light received by the light-receiving unit is also called incident light, and the light emitted by the light source is also called emitted light. The UV-cut film 115 absorbs the ultraviolet light emitted from the reflective light source 111 and reflected from side A of banknote BN, preventing that ultraviolet light from being received by the light-receiving unit 113 via the condensing lens 112.

[0123] The lower unit 120 includes two reflective light sources 121 and one transmissive light source 124, a condensing lens 122, a light receiving unit 123, and a UV-cut film 125. The reflective light sources 121 irradiate the main surface (hereinafter referred to as the B-side) of the banknote BN on the light receiving unit 123 side with illumination light having different wavelength bands, specifically infrared light, white light including red, green, and blue light, and ultraviolet light as excitation light for fluorescence. The condensing lens 122 focuses the light emitted from the reflective light sources 121 and reflected from the B-side of the banknote BN, as well as the fluorescence emitted from the B-side 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 outputs it. The UV-cut film 125 absorbs ultraviolet light emitted from the reflective light source 121 and reflected from the B-side of the banknote BN, preventing that ultraviolet light from being received by the light-receiving unit 123 via the condensing lens 122.

[0124] 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.

[0125] 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.

[0126] 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 9 (main scanning direction, Y direction), and a plurality of LED elements (not shown) provided at both ends (or one end) of the light guide.

[0127] 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, 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. 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.

[0128] 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.

[0129] As shown in Figure 2, each light-receiving unit 113, 123 is equipped with a plurality of pixels 30 arranged in a row in the main scanning direction D1 (the direction perpendicular to the transport direction of the banknote BN, the Y direction). Each pixel 30 is equipped with one first light-receiving element (image sensor) 31B, one second light-receiving element (image sensor) 31G, and one third light-receiving element (image sensor) 31R. The first light-receiving element 31B, the second light-receiving element 31G, and the third light-receiving element 31R are arranged in this order in a row in the main scanning direction D1.

[0130] 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 light image and a reflected light image of side A of the banknote BN based on the output signal of the upper unit 110, and acquires a reflected light image of side B of the banknote BN based on the output signal of the lower unit 120.

[0131] Furthermore, the imaging unit 211 acquires a fluorescence detection signal across the entire banknote BN on both side A and side B of the banknote BN. In other words, the imaging unit 211 can acquire fluorescence images of both side A and side B of the banknote BN.

[0132] Next, the configuration of the paper sheet identification device according to this embodiment will be described using Figure 10. As shown in Figure 10, the paper sheet identification device 200 according to this embodiment includes a detection unit 210, a control unit 220, and a storage unit 230.

[0133] 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.

[0134] The detection unit 210 includes a magnetic detection unit 212 and a thickness detection unit 213, in addition to the imaging unit 211 described above, along the banknote transport path. The imaging unit 211 captures images of the banknotes as described above and outputs an image signal (image data). The magnetic detection unit 212 is equipped with a magnetic sensor (not shown) for measuring magnetism, and detects magnetism such as magnetic ink and security threads printed on the banknotes using the magnetic sensor. The magnetic sensor is a magnetic line sensor in which multiple magnetic detection elements are arranged in a line. The thickness detection unit 213 is equipped with a thickness detection sensor (not shown) for measuring the thickness of the banknotes, and detects tape, double feeding, etc. using the thickness detection sensor. The thickness detection sensor detects the amount of displacement when banknotes pass through rollers facing each other across the transport path using sensors provided on each roller.

[0135] 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 imaging cycle by the imaging unit 211, the timing for 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 for reading signals from the upper unit 110 and the lower unit 120, respectively.

[0136] One cycle of imaging refers to an imaging pattern in which the wavelength range of the light emitted from each light source 111, 121, and 124, as well as the timing of turning each light source 111, 121, and 124 on and off, and reading the signal, are set. One cycle of imaging constitutes one period, and by continuously repeating this process, an image of the entire banknote is acquired.

[0137] The light source control unit 221 performs dynamic lighting control of each light source 111, 121, and 124 in order to capture individual banknote images using each light source 111, 121, and 124. Specifically, the light source control unit 221 controls the lighting and extinguishing of each light source 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.

[0138] 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. 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.

[0139] Here, line data refers to data based on signals obtained from a single image capture by each of the upper unit 110 and the lower unit 120, 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.

[0140] 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.

[0141] The identification unit 223 uses the fluorescence detection signal acquired by the imaging unit 211 to identify the banknote BN.

[0142] More specifically, the identification unit 223 performs the above-described calculation using the fluorescence detection signal corresponding to the identification target area of ​​the fluorescence image to calculate the amount of visible fluorescence (fluorescence emission) of a specific color (blue, green, or red) and the amount of infrared fluorescence (fluorescence emission) of the banknote to be identified. This identification target area may be set according to the denomination of the banknote.

[0143] The identification unit 223 then determines the authenticity of the banknote BN by checking whether the calculated visible light fluorescence intensity (fluorescence emission amount) and infrared light fluorescence intensity (fluorescence emission amount) of the banknote BN to be identified are within an acceptable range with respect to a second reference data concerning the visible light fluorescence intensity (fluorescence emission amount) and infrared light fluorescence intensity (fluorescence emission amount) of a genuine banknote.

[0144] Here, we will explain the calculation process performed by the identification unit 223 in more detail using Figures 11 to 15.

[0145] The following describes how to calculate the amount of green fluorescence and the amount of infrared fluorescence from the fluorescence emitted by a special fluorescent ink that fluoresces in the green and infrared wavelength bands (hereinafter also referred to as green infrared ink).

[0146] First, before shipment or during maintenance of the paper sheet identification device 200, multiple reference media are imaged in advance by the light-receiving section of one of the imaging units 211. As shown in Figure 11, the reference media used are a medium printed with green fluorescent ink that emits fluorescence with a spectrum approximating the spectral component having a peak in the green wavelength band among the fluorescence spectra measured from green infrared ink irradiated with ultraviolet light (see the spectra shown by dashed lines in the left and right graphs in the first row of Figure 11) (see the hatched spectrum in the left graph in the first row of Figure 11), and a medium printed with infrared fluorescent ink that emits fluorescence with a spectrum approximating the spectral component having a peak in the infrared wavelength band among the fluorescence spectra measured from green infrared ink irradiated with ultraviolet light (see the spectra shown by dashed lines in the left and right graphs in the first row of Figure 11) (see the hatched spectrum in the right graph in the first row of Figure 11).

[0147] As shown in the second row on the left of Figure 11, if the output values ​​of the first photodetector 31B, the second photodetector 31G, and the third photodetector 31R when the measurement results of a medium printed with green fluorescent ink, i.e., when only the fluorescence emitted from the green fluorescent ink is received by the photodetector, are denoted as αBg, αGg, and αRg, respectively, then the ratio of the light intensity when the green fluorescent ink emits light is αRg:αGg:αBg.

[0148] In Figures 11 and subsequent figures, CH_B, CH_G, and CH_R represent the first photodetector 31B, the second photodetector 31G, and the third photodetector 31R, respectively, and CH represents a photodetector.

[0149] As shown in the second row on the right of Figure 11, if the output values ​​of the first photodetector 31B, the second photodetector 31G, and the third photodetector 31R when the measurement results of the medium printed with infrared fluorescent ink, i.e., when only the fluorescence emitted from the infrared fluorescent ink is received by the photodetector, are denoted as βBir, βGir, and βRir, respectively, then the ratio of the light intensity when the infrared fluorescent ink emits light is βRir:βGir:βBir.

[0150] These ratios are then stored in the storage unit 230 as the ratios of the true reference data.

[0151] Furthermore, the photodetector with the maximum output value among the RGB outputs of the two fluorescent inks measured in advance is selected (Figure 12, step S31). Here, for the green fluorescent ink, it is assumed that αGg, the output value of the second photodetector 31G, is the maximum value among αBg, αGg, and αRg. For the infrared fluorescent ink, it is assumed that βRir, the output value of the third photodetector 31R, is the maximum value among βBir, βGir, and βRir. Subsequently, calculations are performed using the output values ​​of these two selected photodetectors.

[0152] Next, the fluorescence emitted from the banknote BN to be identified is captured by one of the light-receiving elements of the imaging unit 211. The output values ​​of the first light-receiving element 31B, the second light-receiving element 31G, and the third light-receiving element 31R at this time are denoted as X, Y, and Z, respectively. Then, the amount of light emitted for each color at the output value of one of the two light-receiving elements selected in step S31, namely the amount of green fluorescence and the amount of infrared fluorescence, are calculated (Figure 12, step S32). Here, first, the amount of green fluorescence G_r and the amount of infrared fluorescence IR_r included in the output value Z of the third light-receiving element 31R are calculated.

[0153] Specifically, as shown in Figure 13, the amount of green fluorescence light G_g included in the output value Y of the second photodetector 31G and the amount of green fluorescence light G_r included in the output value Z of the third photodetector 31R are expressed as equation (1) in Figure 13, using the ratio of light intensity αRg:αGg, which is the ratio of light intensity when the green fluorescent ink is emitted. Similarly, the amount of infrared fluorescence light IR_g included in the output value Y of the second photodetector 31G and the amount of infrared fluorescence light IR_r included in the output value Z of the third photodetector 31R are expressed as equation (2) in Figure 13, using the ratio of light intensity βRir:βGir, which is the ratio of light intensity when the infrared fluorescent ink is emitted.

[0154] To eliminate the effect of green fluorescence from the output value Y of the second photodetector 31G and the output value Z of the third photodetector 31R, the left side of equation (3) below should be calculated. This cancels out the amount of green fluorescence from both output values. Furthermore, the output value Y of the second photodetector 31G is the sum of the amount of green fluorescence G_g and the amount of infrared fluorescence IR_g, and the output value Z of the third photodetector 31R is the sum of the amount of green fluorescence G_r and the amount of infrared fluorescence IR_r. Substituting these relationships into the left side of equation (3) below will give the right side of equation (3) below.

[0155]

number

[0156] Next, substituting equation (1) in Figure 13 into the right-hand side of equation (3) yields equation (4) below.

[0157]

number

[0158] Next, substituting equation (2) in Figure 13 into the right-hand side of equation (4), we obtain equation (5) below.

[0159]

number

[0160] By rearranging equation (5), we obtain equation (6) below, and the amount of infrared fluorescence IR_r contained in the output value Z of the third photodetector 31R is calculated from the ratio of the output value Y of the second photodetector 31G, the output value Z of the third photodetector 31R, and the true reference data.

[0161]

number

[0162] Furthermore, since the output value Z of the third photodetector 31R is the sum of the green fluorescence light intensity G_r and the infrared fluorescence light intensity IR_r, the green fluorescence light intensity G_r included in the output value Z of the third photodetector 31R can be calculated from equation (6) above and equation (7) below.

[0163]

number

[0164] Next, the amount of light emitted for each color at the output value of the other of the two photodetectors selected in step S31, namely the amount of green fluorescence and the amount of infrared fluorescence, is calculated (Figure 12, step S33). Here, the amount of green fluorescence G_g and the amount of infrared fluorescence IR_g included in the output value Y of the second photodetector 31G are calculated.

[0165] First, using equations (1) and (2) in Figure 13, the amount of infrared fluorescence IR_g contained in the output value Y of the second photodetector 31G is calculated in the same manner as in equation (6) above, from the ratio of the output value Y of the second photodetector 31G, the output value Z of the third photodetector 31R, and the true reference data (see equation (8) below).

[0166]

number

[0167] Furthermore, since the output value Y of the second photodetector 31G is the sum of the green fluorescence light intensity G_g and the infrared fluorescence light intensity IR_g, the green fluorescence light intensity G_g included in the output value Y of the second photodetector 31G can be calculated from equation (8) above and equation (9) below.

[0168]

number

[0169] While equations (6) to (9) above are stored in the memory unit 230, equations (1) to (5) above do not necessarily need to be stored in the memory unit 230.

[0170] Next, from the RGB outputs of the two fluorescent inks measured in advance and selected in step S31, the amount of light emitted from the output value of the photodetector with the maximum output value is selected (Figure 12, step S34). Here, for the green fluorescent ink, the output value αGg of the second photodetector 31G is the maximum value, so the amount of green fluorescence G_g included in the output value Y of the second photodetector 31G when the banknote BN to be identified is imaged is selected. On the other hand, for the infrared fluorescent ink, the output value βBir of the third photodetector 31R is the maximum value, so the amount of infrared fluorescence IR_r included in the output value Z of the third photodetector 31R when the banknote BN to be identified is imaged is selected.

[0171] Next, the ratio of the two light intensities selected in step S34 is calculated (Figure 12, step S35). That is, the ratio of the green fluorescence light intensity G_g to the infrared fluorescence light intensity IR_r is calculated.

[0172] Then, it is determined whether the calculated light intensity and ratio fall within a predetermined range (within a threshold or predetermined multiplier range relative to the standard) included in the second reference data (Figure 12, step S36). Specifically, it is determined whether the green fluorescence light intensity G_g, the infrared fluorescence light intensity IR_r, and their ratios are within an acceptable range relative to the second reference data.

[0173] Alternatively, instead of using the infrared fluorescence intensity IR_r, the infrared fluorescence intensity IR_g may be selected, and the green fluorescence intensity G_g, the infrared fluorescence intensity IR_g, and their ratios may be judged against a second reference data to determine whether they are within the acceptable range. In this case as well, similar judgment results can be obtained.

[0174] Next, we will explain how to calculate the amount of red fluorescence and the amount of infrared fluorescence from a special fluorescent ink that emits fluorescence in the red and infrared wavelength bands (hereinafter also referred to as red infrared ink).

[0175] First, before shipment or during maintenance of the paper sheet identification device 200, multiple reference media are imaged in advance by the light-receiving section of one of the imaging units 211. The reference media used are a medium printed with red fluorescent ink that emits fluorescence with a spectrum approximating the spectral component having a peak in the red wavelength band in the fluorescence spectrum measured from red infrared ink irradiated with ultraviolet light, and a medium printed with infrared fluorescent ink that emits fluorescence with a spectrum approximating the spectral component having a peak in the infrared wavelength band in the fluorescence spectrum measured from red infrared ink irradiated with ultraviolet light.

[0176] As shown on the left of Figure 14, if the output values ​​of the first photodetector 31B, the second photodetector 31G, and the third photodetector 31R when the measurement results of a medium printed with red fluorescent ink, i.e., when only the fluorescence emitted from the red fluorescent ink is received by the photodetector, are denoted as γBr, γGr, and γRr, respectively, then the ratio of the light intensity when the red fluorescent ink emits light is γRr:γGr:γBr.

[0177] As shown on the right of Figure 14, if the output values ​​of the first photodetector 31B, the second photodetector 31G, and the third photodetector 31R when the measurement results of the medium printed with infrared fluorescent ink, i.e., when only the fluorescence emitted from the infrared fluorescent ink is received by the photodetector, are denoted as βBir, βGir, and βRir, respectively, then the ratio of the light intensity when the infrared fluorescent ink emits light is βRir:βGir:βBir.

[0178] These ratios are then stored in the storage unit 230 as the ratios of the true reference data.

[0179] Furthermore, the photodetector with the maximum output value among the RGB outputs of the two fluorescent inks measured in advance is selected (Figure 12, step S31). However, if the output value of the same photodetector is the maximum, the photodetector with the maximum output value and the photodetector with the second largest output value among the RGB outputs of the visible fluorescent ink measured in advance are selected. Here, for the red fluorescent ink, γRr, which is the output value of the third photodetector 31R, is assumed to be the maximum value among γBr, γGr, and γRr, and for the infrared fluorescent ink, βRir, which is the output value of the third photodetector 31R, is assumed to be the maximum value among βBir, βGir, and βRir. Also, for the red fluorescent ink, γGr, which is the output value of the second photodetector 31G, is assumed to be the second largest value among γBr, γGr, and γRr. Therefore, calculations are performed using the output values ​​of the second photodetector 31G and the third photodetector 31R from here on.

[0180] Next, the fluorescence emitted from the banknote BN to be identified is captured by one of the light-receiving elements of the imaging unit 211. The output values ​​of the first light-receiving element 31B, the second light-receiving element 31G, and the third light-receiving element 31R at this time are denoted as X, Y, and Z, respectively. Then, the amount of light emitted for each color at the output value of one of the two light-receiving elements selected in step S31, i.e., the amount of red fluorescence and the amount of infrared fluorescence, are calculated (Figure 12, step S32). If the output value of the same light-receiving element is the maximum among the RGB outputs of the two fluorescent inks measured in advance, the amount of red fluorescence R_r and the amount of infrared fluorescence IR_r included in the output value Z of the light-receiving element with the maximum output value, i.e., the third light-receiving element 31R, are calculated.

[0181] Specifically, as shown in Figure 15, the amount of red fluorescence light R_g included in the output value Y of the second photodetector 31G and the amount of red fluorescence light R_r included in the output value Z of the third photodetector 31R are expressed as equation (11) in Figure 15, using γRr:γGr, which is the ratio of the light intensity when the red fluorescent ink is emitted. Similarly, the amount of infrared fluorescence light IR_g included in the output value Y of the second photodetector 31G and the amount of infrared fluorescence light IR_r included in the output value Z of the third photodetector 31R are expressed as equation (12) in Figure 15, using βRir:βGir, which is the ratio of the light intensity when the infrared fluorescent ink is emitted.

[0182] To eliminate the effect of red fluorescence from the output value Y of the second photodetector 31G and the output value Z of the third photodetector 31R, the left side of equation (13) below should be calculated. This will cancel out the amount of red fluorescence from both output values. Furthermore, the output value Y of the second photodetector 31G is the sum of the amount of red fluorescence R_g and the amount of infrared fluorescence IR_g, and the output value Z of the third photodetector 31R is the sum of the amount of red fluorescence R_r and the amount of infrared fluorescence IR_r. Substituting these relationships into the left side of equation (13) below will give the right side of equation (13) below.

[0183]

number

[0184] Next, substituting equation (11) in Figure 15 into the right-hand side of equation (13) yields equation (14) below.

[0185]

number

[0186] Next, substituting equation (12) in Figure 15 into the right-hand side of equation (14) yields equation (15) below.

[0187]

number

[0188] By rearranging equation (15), we obtain equation (16) below, and the amount of infrared fluorescence IR_r contained in the output value Z of the third photodetector 31R is calculated from the ratio of the output value Y of the second photodetector 31G, the output value Z of the third photodetector 31R, and the true reference data.

[0189]

number

[0190] Furthermore, since the output value Z of the third photodetector 31R is the sum of the red fluorescence light intensity R_r and the infrared fluorescence light intensity IR_r, the red fluorescence light intensity R_r included in the output value Z of the third photodetector 31R can be calculated from equation (16) above and equation (17) below.

[0191]

number

[0192] Although equations (16) and (17) above are stored in the storage unit 230, equations (11) to (15) above do not necessarily need to be stored in the storage unit 230.

[0193] Next, as shown in step S33 of Figure 12, the amount of light emitted for each color at the output value of the other of the two photodetectors selected in step S31, i.e., the amount of red fluorescence R_g and the amount of infrared fluorescence IR_g included in the output value Y of the second photodetector 31G, may be calculated in the same manner, but this calculation is not required.

[0194] Next, from the RGB outputs of the two fluorescent inks selected in step S31 and measured in advance, the amount of light emitted from the output value of the photodetector with the maximum output value is selected (Figure 12, step S34). Here, for the red fluorescent ink, the output value γRr of the third photodetector 31R is the maximum value, so the amount of red fluorescence light R_r included in the output value Z of the third photodetector 31R when the banknote BN to be identified is imaged is selected. Similarly, for the infrared fluorescent ink, the output value βRir of the third photodetector 31R is the maximum value, so the amount of infrared fluorescence light IR_r included in the output value Z of the third photodetector 31R when the banknote BN to be identified is imaged is selected.

[0195] Next, the ratio of the two light intensities selected in step S34 is calculated (Figure 12, step S35). That is, the ratio of the red fluorescence intensity R_r to the infrared fluorescence intensity IR_r is calculated.

[0196] Then, it is determined whether the calculated light intensity and ratio fall within a predetermined range (within a threshold or predetermined multiplier range relative to the standard) included in the second reference data (Figure 12, step S36). Specifically, it is determined whether the red fluorescence intensity R_r, the infrared fluorescence intensity IR_r, and their ratios are within an acceptable range relative to the second reference data.

[0197] (Variation 1) In the above embodiment, the case in which the amount of green or red fluorescence and the amount of infrared fluorescence are calculated using the output value of the second photodetector 31G and the output value of the third photodetector 31R has been described. However, the amount of blue, green, or red fluorescence and the amount of infrared fluorescence may be similarly calculated using combinations of the output values ​​of other photodetectors. For example, the amount of infrared fluorescence IR_g (see formula (21) below) included in the output value Y of the second photodetector 31G (see formula (22) below) may be calculated using the output value X of the first photodetector 31B, the output value Y of the second photodetector 31G, the ratio αGg:αBg which is the light intensity when the green fluorescent ink is emitted, and the ratio βGir:βBir which is the light intensity when the infrared fluorescent ink is emitted. In this case, these formulas may be stored in the storage unit 230.

[0198]

number

[0199]

number

[0200] (Modification 2) In the above embodiment, the case in which the light-receiving unit constitutes an optical line sensor that acquires optical data (optical characteristics) of banknotes over the entire width of the transport path was described. However, the light-receiving unit may also be a point sensor that acquires optical data (optical characteristics) of banknotes at one point in the width of the transport path.

[0201] (Variation 3) 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 is received by the light receiving unit after the ultraviolet light used as excitation light is turned off, and a phosphorescence detection signal is output. This phosphorescence detection signal can be used to perform identification processing in the same way as the fluorescence detection signal. For example, the banknote to be identified can be identified by determining whether the amount of phosphorescence emission in visible light and infrared light of the banknote to be identified is within an acceptable range with respect to reference data regarding the amount of phosphorescence emission in visible light and infrared light of a genuine banknote. 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 as excitation 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, so it can function as a highly secure security element.

[0202] 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]

[0203] As described above, this disclosure is a useful technique for simultaneously and easily obtaining visible and infrared data without using filter configurations that are difficult to manufacture. [Explanation of Symbols]

[0204] 1,200: Paper sheet identification device 11, 111, 121, 124: Light source 13, 113, 123: Light receiving section 23, 223: Identification section 30 pixels 31, 31B, 31G, 31R: Photodetector 32, 32B, 32G, 32R: Color filters 33: Photodetector 110: Upper unit 112, 122: Focusing lens 115, 125: UV-cut film 120: Lower unit 210: Detection unit 211: Imaging Department 212: Magnetic detection unit 213: Thickness detection unit 220: Control Unit 221: Light source control unit 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 BN:Banknote

Claims

1. A light source capable of irradiating the paper sheets to be identified with light of a specific wavelength, A light-receiving unit has multiple light-receiving elements, each equipped with multiple color filters that transmit infrared light and have different visible light transmission characteristics, and receives light arriving from the paper sheets to be identified based on light from the light source with each of the multiple light-receiving elements and outputs a light detection signal, An identification unit calculates the amount of light of at least one color of visible light and the amount of infrared light by performing calculations on the light intensity data based on each light detection signal output from the light receiving unit, based on the ratio of true reference data, and identifies the paper sheets based on the calculation results. A paper sheet identification device characterized by being equipped with the following features.

2. The plurality of light-receiving elements include a first light-receiving element having a color filter that transmits blue light and infrared light, a second light-receiving element having a color filter that transmits green light and infrared light, and a third light-receiving element having a color filter that transmits red light and infrared light. The ratio of the true reference data includes the ratio of the output values ​​of at least two of the first, second, and third photodetectors. The paper sheet identification device according to claim 1, characterized in that it is a paper sheet identification device.

3. The light of the specific wavelength emitted by the light source is ultraviolet light. The light-receiving unit receives the photoluminescence of visible light and infrared light emitted from the paper sheets to be identified, which have been irradiated with ultraviolet light, and outputs a visible light photoluminescence detection signal and an infrared light photoluminescence detection signal as the light detection signals. The identification unit uses the visible light photoluminescence detection signal and the infrared light photoluminescence detection signal output from the light receiving unit to identify the paper sheets to be identified. The paper sheet identification device according to claim 1 or 2, characterized in that it is a paper sheet identification device.

4. Genuine paper sheets irradiated with ultraviolet light emit photoluminescence in both visible and infrared light regions. The plurality of light-receiving elements include a first light-receiving element having a color filter that transmits blue light and infrared light, a second light-receiving element having a color filter that transmits green light and infrared light, and a third light-receiving element having a color filter that transmits red light and infrared light. The ratio of the genuine reference data includes the ratio of at least two output values ​​among the output values ​​of the first light-receiving element, the second light-receiving element, and the third light-receiving element when the light-receiving unit receives only photoluminescence equivalent to the visible light photoluminescence emitted by the genuine paper sheets, and the ratio of at least two output values ​​among the output values ​​of the first light-receiving element, the second light-receiving element, and the third light-receiving element when the light-receiving unit receives only photoluminescence equivalent to the infrared light photoluminescence emitted by the genuine paper sheets. The paper sheet identification device according to claim 3, characterized in that it is a paper sheet identification device.

5. Genuine paper sheets irradiated with ultraviolet light emit green photoluminescence and infrared photoluminescence in the same region. The output values ​​of the first light-receiving element, the second light-receiving element, and the third light-receiving element when the light-receiving unit receives only photoluminescence equivalent to the green photoluminescence emitted by the genuine paper sheets are defined as αBg, αGg, and αRg, respectively. The output values ​​of the first light-receiving element, the second light-receiving element, and the third light-receiving element when the light-receiving unit receives only photoluminescence equivalent to the photoluminescence of the infrared light emitted by the genuine paper sheets are defined as βBir, βGir, and βRir, respectively. If the output values ​​of the first light-receiving element, the second light-receiving element, and the third light-receiving element when the photoluminescence emitted from the paper sheets to be identified is received by the light-receiving unit are X, Y, and Z, respectively, The identification unit calculates G_g and IR_r based on the following formulas (I) to (III), and uses the calculated G_g and IR_r to identify the paper sheets to be identified. [Math 1] (Here, IR_g represents the amount of infrared photoluminescence emitted from the paper sheets to be identified, among the output values ​​of the second light-receiving element when the light-receiving unit receives photoluminescence emitted from the paper sheets to be identified; G_g represents the amount of green photoluminescence emitted from the paper sheets to be identified, among the output values ​​of the second light-receiving element when the light-receiving unit receives photoluminescence emitted from the paper sheets to be identified; and IR_r represents the amount of infrared photoluminescence emitted from the paper sheets to be identified, among the output values ​​of the third light-receiving element when the light-receiving unit receives photoluminescence emitted from the paper sheets to be identified.) The paper sheet identification device according to claim 4, characterized in that it is a paper sheet identification device.

6. Genuine paper sheets irradiated with ultraviolet light emit green photoluminescence and infrared photoluminescence in the same region. The output values ​​of the first light-receiving element, the second light-receiving element, and the third light-receiving element when the light-receiving unit receives only photoluminescence equivalent to the green photoluminescence emitted by the genuine paper sheets are defined as αBg, αGg, and αRg, respectively. The output values ​​of the first light-receiving element, the second light-receiving element, and the third light-receiving element when the light-receiving unit receives only photoluminescence equivalent to the photoluminescence of the infrared light emitted by the genuine paper sheets are defined as βBir, βGir, and βRir, respectively. If the output values ​​of the first light-receiving element, the second light-receiving element, and the third light-receiving element when the photoluminescence emitted from the paper sheets to be identified is received by the light-receiving unit are X, Y, and Z, respectively, The identification unit calculates G_g and IR_g based on the following formulas (I) and (II), and uses the calculated G_g and IR_g to identify the paper sheets to be identified. [Math 2] (Here, IR_g represents the amount of infrared photoluminescence emitted from the paper sheets to be identified, among the output values ​​of the second light-receiving element when the light-receiving unit receives photoluminescence emitted from the paper sheets to be identified, and G_g represents the amount of green photoluminescence emitted from the paper sheets to be identified, among the output values ​​of the second light-receiving element when the light-receiving unit receives photoluminescence emitted from the paper sheets to be identified.) The paper sheet identification device according to claim 4, characterized in that it is a paper sheet identification device.

7. Genuine paper sheets irradiated with ultraviolet light emit red and infrared photoluminescence in the same region. When the light-receiving unit receives only photoluminescence equivalent to the red photoluminescence emitted by the genuine paper sheets, the output values ​​of the first light-receiving element, the second light-receiving element, and the third light-receiving element are denoted as γBr, γGr, and γRr, respectively. The output values ​​of the first light-receiving element, the second light-receiving element, and the third light-receiving element when the light-receiving unit receives only photoluminescence equivalent to the photoluminescence of the infrared light emitted by the genuine paper sheets are defined as βBir, βGir, and βRir, respectively. If the output values ​​of the first light-receiving element, the second light-receiving element, and the third light-receiving element when the photoluminescence emitted from the paper sheets to be identified is received by the light-receiving unit are X, Y, and Z, respectively, The identification unit calculates R_r and IR_r based on the following formulas (IV) and (V), and uses the calculated R_r and IR_r to identify the paper sheets to be identified. [Math 3] (Here, R_r represents the amount of red photoluminescence emitted from the paper sheets to be identified, among the output values ​​of the third light-receiving element when the photoluminescence emitted from the paper sheets to be identified is received by the light-receiving unit, and IR_r represents the amount of infrared photoluminescence emitted from the paper sheets to be identified, among the output values ​​of the third light-receiving element when the photoluminescence emitted from the paper sheets to be identified is received by the light-receiving unit.) The paper sheet identification device according to claim 4, characterized in that it is a paper sheet identification device.

8. The identification unit uses the visible light photoluminescence detection signal and the infrared light photoluminescence detection signal output from the light receiving unit to identify the paper sheets to be identified based on whether the visible light photoluminescence emission amount and the infrared light photoluminescence emission amount of the paper sheets to be identified are within an acceptable range relative to a second reference data relating to the visible light photoluminescence emission amount and infrared light photoluminescence emission amount of genuine paper sheets. A paper sheet identification device according to any one of features 3 to 7.

9. The second reference data includes the ratio of the amount of photoluminescent emission in visible light to the amount of photoluminescent emission in infrared light, The identification unit calculates the ratio of the visible light photoluminescence emission amount to the infrared light photoluminescence emission amount of the paper sheets to be identified, and identifies the paper sheets to be identified based on whether or not this ratio is within an acceptable range with respect to the ratio included in the second reference data. The paper sheet identification device according to claim 8, characterized in that it is a paper sheet identification device.

10. The light-receiving unit receives photoluminescence of at least one color from blue, green, and red as visible light photoluminescence and outputs a photoluminescence detection signal of the at least one color. The second reference data relates to the photoluminescent emission amount of at least one color and the photoluminescent emission amount of infrared light, The identification unit identifies the paper sheets to be identified based on whether the photoluminescence emission amount of at least one color and the photoluminescence emission amount of infrared light of the paper sheets to be identified are within an acceptable range with respect to the second reference data. The paper sheet identification device according to claim 8 or 9, characterized in that it is as described above.

11. The light-receiving unit receives green photoluminescence as visible light photoluminescence and outputs a green photoluminescence detection signal. The second reference data mentioned above pertains to the photoluminescence emission amount of green light and the photoluminescence emission amount of infrared light. The identification unit identifies the paper sheets to be identified based on whether the amount of green photoluminescence emission and infrared photoluminescence emission of the paper sheets to be identified are within an acceptable range relative to the second reference data. The paper sheet identification device according to claim 10, characterized in that it is a paper sheet identification device.

12. The light-receiving unit receives red photoluminescence as visible light photoluminescence and outputs a red photoluminescence detection signal. The second reference data mentioned above pertains to the photoluminescent emission amount of red light and the photoluminescent emission amount of infrared light. The identification unit identifies the paper sheets to be identified based on whether the amount of red photoluminescence emission and infrared photoluminescence emission of the paper sheets to be identified are within an acceptable range relative to the second reference data. The paper sheet identification device according to claim 10, characterized in that it is a paper sheet identification device.

13. The light-receiving unit receives blue photoluminescence as visible light photoluminescence and outputs a blue photoluminescence detection signal. The second reference data mentioned above pertains to the photoluminescence emission amount of blue light and the photoluminescence emission amount of infrared light. The identification unit identifies the paper sheets to be identified based on whether the amount of blue photoluminescence emission and infrared photoluminescence emission of the paper sheets to be identified are within an acceptable range relative to the second reference data. The paper sheet identification device according to claim 10, characterized in that it is a paper sheet identification device.

14. The light-receiving unit receives near-infrared photoluminescence as infrared photoluminescence and outputs a near-infrared photoluminescence detection signal. The second reference data mentioned above pertains to the photoluminescence emission amount in the visible light and the photoluminescence emission amount in the near-infrared, The identification unit identifies the paper sheets to be identified based on whether the visible light photoluminescence emission amount and near-infrared photoluminescence emission amount of the paper sheets to be identified are within an acceptable range relative to the second reference data. A paper sheet identification device according to any one of 8 to 13.

15. A paper sheet processing apparatus characterized by comprising a paper sheet identification device according to any one of claims 1 to 14.

16. The first step involves irradiating the paper sheets to be identified with light of a specific wavelength from a light source, A second step involves receiving light from the paper sheets to be identified based on the light from the light source using each of the multiple light-receiving elements in the light-receiving unit, and outputting a light detection signal from each of them. A third step involves using the light detection signals output from the light receiving unit to identify the paper sheets to be identified, Equipped with, Each of the aforementioned multiple light-receiving elements is equipped with multiple color filters that transmit infrared light and have different visible light transmission characteristics. In the third step, the light intensity data based on each light detection signal output from the light receiving unit is calculated based on the ratio of true reference data to determine the light intensity of at least one color of visible light and the light intensity of infrared light, and the paper sheets are identified based on the calculation results. A method for identifying paper sheets, characterized by the features described above.

17. A first process involves irradiating the paper sheets to be identified with light of a specific wavelength from a light source, A second process involves receiving light from the paper sheets to be identified based on the light from the light source, using each of the multiple light-receiving elements in the light-receiving unit, and outputting a light detection signal from each. A third process is performed to identify the paper sheets to be identified using the light detection signals output from the light receiving unit, This is to be performed by the paper sheet identification device. Each of the aforementioned multiple light-receiving elements is equipped with multiple color filters that transmit infrared light and have different visible light transmission characteristics. In the third process, the light intensity data based on each light detection signal output from the light receiving unit is calculated based on the ratio of true reference data to determine the light intensity of at least one color of visible light and the light intensity of infrared light, and the paper sheets are identified based on the calculation results. A paper sheet identification program characterized by the following features.

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