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 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 paper sheets to be identified with light of a specific wavelength; a light receiving unit that receives light arriving from the paper sheets to be identified based on the light from the light source and outputs a light detection signal; and an identification unit that identifies the paper sheets to be identified using the light detection signal output from the light receiving unit, wherein the light receiving unit comprises: 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; a third light receiving element having a color filter that transmits red light and infrared light; and a fourth light receiving element having a color filter that transmits only one of the following types of light: blue light, green light, red light, and infrared light.

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, photoluminescence compounds are known as security elements attached to paper sheets such as banknotes. Photoluminescence compounds are excited by ultraviolet light or the like and produce fluorescence emission or phosphorescence emission. As methods 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, while irradiating visible light, light other than visible light (infrared light / ultraviolet light) is simultaneously irradiated to acquire visible color information, and after all the lights are turned off, IR information is acquired as phosphorescence, so that color information of visible light and light other than visible light can be acquired with a small number of lighting times.

[0004] In addition, Patent Document 1 describes a second embodiment in which four light receiving elements are linearly arranged 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. However, these color filters (R), (G), and (B) do not transmit ultraviolet light and infrared light. Further, 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] 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 obtain visible and infrared data without using a filter configuration that is difficult to manufacture. [Means for solving the problem]

[0009] 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 comprises: a light source capable of irradiating a paper sheet to be identified with light of a specific wavelength; a light receiving unit that receives light arriving from the paper sheet to be identified based on the light from the light source and outputs a light detection signal; and an identification unit that identifies the paper sheet to be identified using the light detection signal output from the light receiving unit, wherein the light receiving unit comprises: 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; a third light receiving element having a color filter that transmits red light and infrared light; and a fourth light receiving element having a color filter that transmits only one of the following types of light: blue light, green light, red light, and infrared light.

[0010] (2) In the paper sheet identification device described in (1) above, the identification unit may subtract the output value of the fourth light-receiving element from at least one of 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, and use the result of the subtraction to identify the paper sheet to be identified.

[0011] (3) In the paper sheet identification device described in (2) above, the color filter of the fourth light-receiving element may transmit only infrared light, and the identification unit may calculate at least one of the amounts of blue light, green light, and red light as the subtraction result by subtracting the output value of the fourth light-receiving element from at least one of 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.

[0012] (4) In the paper sheet identification device described in (2) above, the color filter of the fourth light-receiving element may transmit only blue light, and the identification unit may calculate the amount of infrared light as the subtraction result by subtracting the output value of the fourth light-receiving element from the output value of the first light-receiving element.

[0013] (5) In the paper sheet identification device described in (4) above, the identification unit may further calculate at least one of the green light intensity and the red light intensity as the subtraction result by subtracting the amount of infrared light from at least one of the output value of the second light receiving element and the output value of the third light receiving element.

[0014] (6) In the paper sheet identification device described in (2) above, the color filter of the fourth light-receiving element may transmit only green light, and the identification unit may calculate the amount of infrared light as the subtraction result by subtracting the output value of the fourth light-receiving element from the output value of the second light-receiving element.

[0015] (7) In the paper sheet identification device described in (6) above, the identification unit may further calculate at least one of the blue light intensity and the red light intensity as the subtraction result by subtracting the amount of infrared light from at least one of the output value of the first light receiving element and the output value of the third light receiving element.

[0016] (8) In the paper sheet identification device described in (2) above, the color filter of the fourth light-receiving element may transmit only red light, and the identification unit may calculate the amount of infrared light as the subtraction result by subtracting the output value of the fourth light-receiving element from the output value of the third light-receiving element.

[0017] (9) In the paper sheet identification device described in (8) above, the identification unit may further calculate at least one of the blue light intensity and the green light intensity as the subtraction result by subtracting the amount of infrared light from at least one of the output value of the first light receiving element and the output value of the second light receiving element.

[0018] (10) In the paper sheet identification device described in any of (1) to (9) above, the first light-receiving element, the second light-receiving element, the third light-receiving element, and the fourth light-receiving element may be arranged in a single row in the main scanning direction.

[0019] (11) In the paper sheet identification device described in any of (1) to (9) above, the first light-receiving element, the second light-receiving element, and the third light-receiving element may be arranged in a row along a first reference line parallel to the main scanning direction, and the fourth light-receiving element may be arranged in a row along a second reference line parallel to the main scanning direction and located at a position shifted from the first reference line in the sub-scanning direction.

[0020] (12) In the paper sheet identification device described in any of (1) to (11) above, the light of a specific wavelength irradiated by the light source may be ultraviolet light, the light receiving unit may receive photoluminescence emitted from the paper sheets to be identified that have been irradiated with the ultraviolet light and output a photoluminescence detection signal as the light detection signal, and the identification unit may use the photoluminescence detection signal output from the light receiving unit to identify the paper sheets to be identified.

[0021] (13) In the paper sheet identification device described in (12) above, the identification unit may identify the paper sheet to be identified based on whether the amount of visible light photoluminescence emission and infrared light photoluminescence emission of the paper sheet to be identified is within an acceptable range with respect to reference data relating to the amount of visible light photoluminescence emission and infrared light photoluminescence emission of a genuine paper sheet.

[0022] (14) In the paper sheet identification device described in (13) above, the 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 reference data.

[0023] (15) In the paper sheet discrimination device according to (13) or (14) above, the light receiving unit may receive at least one color of photoluminescence among blue, green, and red as the photoluminescence of visible light and output a detection signal for the at least one color of photoluminescence. The reference data may relate to the emission amount of the at least one color of photoluminescence and the emission amount of infrared photoluminescence. The discrimination unit may discriminate the paper sheet to be discriminated based on whether the emission amount of the at least one color of photoluminescence and the emission amount of infrared photoluminescence of the paper sheet to be discriminated are within an allowable range with respect to the reference data.

[0024] (16) In the paper sheet discrimination device according to (15) above, the light receiving unit may receive green photoluminescence as the photoluminescence of visible light and output a detection signal for green photoluminescence. The reference data may relate to the emission amount of green photoluminescence and the emission amount of infrared photoluminescence. The discrimination unit may discriminate the paper sheet to be discriminated based on whether the emission amount of green photoluminescence and the emission amount of infrared photoluminescence of the paper sheet to be discriminated are within an allowable range with respect to the reference data.

[0025] (17) In the paper sheet discrimination device according to (15) above, the light receiving unit may receive red photoluminescence as the photoluminescence of visible light and output a detection signal for red photoluminescence. The reference data may relate to the emission amount of red photoluminescence and the emission amount of infrared photoluminescence. The discrimination unit may discriminate the paper sheet to be discriminated based on whether the emission amount of red photoluminescence and the emission amount of infrared photoluminescence of the paper sheet to be discriminated are within an allowable range with respect to the reference data.

[0026] (18) In the paper sheet discrimination device according to (15) above, the light receiving unit may receive blue photoluminescence as visible light photoluminescence and output a blue photoluminescence detection signal. The reference data may relate to the blue photoluminescence emission amount and the infrared light photoluminescence emission amount. The discrimination unit may discriminate the paper sheet to be discriminated based on whether the blue photoluminescence emission amount and the infrared light photoluminescence emission amount of the paper sheet to be discriminated are within an allowable range with respect to the reference data.

[0027] (19) In the paper sheet discrimination device according to any one of (13) to (18) above, the light receiving unit may receive near-infrared photoluminescence as infrared light photoluminescence and output a near-infrared photoluminescence detection signal. The reference data may relate to the visible light photoluminescence emission amount and the near-infrared photoluminescence emission amount. The discrimination unit may discriminate the paper sheet to be discriminated based on whether the visible light photoluminescence emission amount and the near-infrared photoluminescence emission amount of the paper sheet to be discriminated are within an allowable range with respect to the reference data.

[0028] (20) Further, the paper sheet processing device according to the second aspect of the present disclosure includes the paper sheet discrimination device according to any one of (1) to (19) above.

[0029] (21) A method for identifying sheets of paper according to a third aspect of the present disclosure comprises the steps of: irradiating sheets of paper to be identified with light of a specific wavelength from a light source; receiving light from the sheets of paper to be identified based on the light from the light source with a light receiving unit and outputting a light detection signal; and identifying the sheets of paper to be identified using the light detection signal output from the light receiving unit, wherein the light receiving unit includes 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; a third light receiving element having a color filter that transmits red light and infrared light; and a fourth light receiving element having a color filter that transmits only one of the following types of light: blue light, green light, red light, and infrared light.

[0030] (22) 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 processes: irradiating a paper sheet to be identified with light of a specific wavelength from a light source; receiving light from the paper sheet to be identified based on the light from the light source and outputting a light detection signal; and identifying the paper sheet to be identified using the light detection signal output from the light receiving device, wherein the light receiving device includes 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; a third light receiving element having a color filter that transmits red light and infrared light; and a fourth light receiving element having a color filter that transmits only one of the following types of light: blue light, green light, red light, and infrared light. [Effects of the Invention]

[0031] 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 obtain visible-range data and infrared-range data without using a filter configuration that is difficult to manufacture. [Brief explanation of the drawing]

[0032] [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 plan 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 schematic plan view illustrating another example of the configuration of the light-receiving unit of the paper sheet identification device according to Embodiment 1. [Figure 5] Figure 4 is a schematic diagram showing an example of the wavelength characteristics of the color filter in the light-receiving section. [Figure 6] Figure 2 is a schematic diagram illustrating an example of subtraction processing by an identification unit using the output value of the light receiving unit. [Figure 7] Figure 4 is a schematic diagram illustrating an example of subtraction processing by an identification unit using the output value of the light receiving unit. [Figure 8] This is a schematic plan view illustrating yet another example of the configuration of the light-receiving unit of the paper sheet identification device according to Embodiment 1. [Figure 9] This is a schematic plan view illustrating yet another example of the configuration of the light-receiving unit of the paper sheet identification device according to Embodiment 1. [Figure 10] This is a schematic plan view illustrating yet another example of the configuration of the light-receiving unit of the paper sheet identification device according to Embodiment 1. [Figure 11] This is a flowchart illustrating an example of the operation of the paper sheet identification device according to Embodiment 1. [Figure 12] This is a schematic plan view of an example of a genuine banknote, showing its appearance under visible light illumination. [Figure 13] This is a schematic plan view of an example of genuine banknote, showing its appearance under ultraviolet light irradiation. [Figure 14] This is a flowchart illustrating an example of the operation of the paper sheet identification device according to Embodiment 2. [Figure 15] This is a schematic perspective view showing the external appearance of an example of a paper sheet processing device according to Embodiment 3. [Figure 16]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 17] This is a block diagram illustrating an example of the configuration of a paper sheet identification device according to Embodiment 3. [Modes for carrying out the invention]

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] (Embodiment 1) The configuration of the paper sheet identification device according to this embodiment will be explained using Figure 1.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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).

[0042] The light-receiving unit 13 may be equipped with first to fourth 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.

[0043] 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.

[0044] 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.

[0045] 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 of imaging being considered as one period.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] Multiple wavelength bands that the light-receiving unit 13 can selectively receive include red (R), green (G), blue (B), infrared (IR), and others.

[0051] 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.

[0052] In this embodiment, as shown in Figures 2 and 3, the light-receiving unit 13 includes 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, a third light-receiving element 31R having a color filter 32R that transmits red light and infrared light, and a fourth light-receiving element 31 having a color filter 32 that transmits only one type of light from among blue light, green light, red light, and infrared light. Therefore, 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. In contrast, the fourth light-receiving element 31 receives only one type of light from among blue light, green light, red light, and infrared light. Furthermore, color filter 32B absorbs green and red light, color filter 32G absorbs blue and red light, and color filter 32R absorbs blue and green light. Color filter 32 absorbs the remaining three types of light from blue, green, red, and infrared light, excluding the light that is transmitted.

[0053] In the examples shown in Figures 2 and 3, the fourth photodetector 31 is a fourth photodetector 31IR having a color filter 32IR that transmits only infrared light.

[0054] Furthermore, in this embodiment, the fourth light-receiving element 31 may be a fourth light-receiving element having a color filter that transmits only one type of light from blue light, green light, and red light. In the example shown in Figures 4 and 5, the fourth light-receiving element 31 may be a fourth light-receiving element 31g having a color filter 32g that transmits only green light.

[0055] A light-receiving unit 13 equipped with such a filter configuration (color filters 32B, 32G, 32R, 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, by a simple calculation process using the output values ​​of each light-receiving element that simultaneously receives light arriving from banknote BN, it is possible to calculate the amount of light for each wavelength band detected by each light-receiving element, specifically the amount of blue light, the amount of green light, and the amount of red light, as well as the amount of infrared light. Therefore, according to this embodiment, it is possible to obtain visible range data and infrared range data simultaneously 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] Next, we will explain the calculation process performed by the identification unit 23 using the output values ​​of each light-receiving element.

[0058] The identification unit 23 may subtract the output value of the fourth light-receiving element 31 from at least one of the output values ​​of the first light-receiving element 31B, the second light-receiving element 31G, and the third light-receiving element 31R, and use the result of this subtraction to identify the banknote BN to be identified. Since the color filters 32B, 32G, and 32R transmit visible light and infrared light, the output values ​​of the first to third light-receiving elements are values ​​corresponding to the sum of the amount of visible light and the amount of infrared light received. However, the color filter 32 of the fourth light-receiving element 31 transmits only one type of light from blue light, green light, red light, and infrared light (hereinafter also referred to as a specific monochromatic light), so the output value of the fourth light-receiving element 31 is a value corresponding only to the amount of that specific monochromatic light. Therefore, through the above subtraction process, if the specific monochromatic light is infrared light, only the output caused by the infrared light is canceled from the outputs of the first to third photodetectors, and the light intensity of blue light, green light, and red light are calculated, respectively. In this case, the identification unit 23 can identify the banknote BN to be identified based on the light intensity of blue light, green light, and red light, which are the results of this subtraction process, and the light intensity of infrared light, which is the output value of the fourth photodetector 31. Furthermore, if the specific monochromatic light is blue light, green light, or red light, through the above subtraction process, only the output caused by the specific monochromatic light is canceled from the output of any of the first to third photodetectors that receive the same light as the specific monochromatic light, and the light intensity of infrared light is calculated. In this case, the identification unit 23 can identify the banknote BN to be identified based on the light intensity of infrared light, which is the result of this subtraction process, and the light intensity of the specific monochromatic light, which is the output value of the fourth photodetector 31.

[0059] If the color filter 32 of the fourth light-receiving element 31 transmits only infrared light, that is, if the fourth light-receiving element 31IR is provided as the fourth light-receiving element 31 and has a color filter 32IR that transmits only infrared light (see Figures 2 and 3), the identification unit 23 may calculate at least one of the light intensity of blue light, green light, and red light as the subtraction result by subtracting the output value of the fourth light-receiving element 31IR from at least one of the output values ​​of the first light-receiving element 31B, the second light-receiving element 31G, and the third light-receiving element 31R.

[0060] In this case, as shown in the first row of Figure 6, the outputs of the first photodetector 31B, the second photodetector 31G, and the third photodetector 31R include a component (IR) due to the amount of infrared light in addition to the component (B, G, or R) due to the amount of visible light. In contrast, as shown in the second row of Figure 6, the output of the fourth photodetector 31IR consists only of the component (IR) due to the amount of infrared light. Therefore, by subtracting the output value of the fourth photodetector 31IR from the output values ​​of the first photodetector 31B, the second photodetector 31G, and the third photodetector 31R, the amounts of blue light only (B), green light only (G), and red light only (R) can be calculated, as shown in the third row of Figure 6.

[0061] If the color filter 32 of the fourth light-receiving element 31 transmits only green light, that is, if the fourth light-receiving element 31g is provided with a color filter 32g that transmits only green light (see Figures 4 and 5), the identification unit 23 may calculate the amount of infrared light as the subtraction result by subtracting the output value of the fourth light-receiving element 31g from the output value of the second light-receiving element 31G.

[0062] In this case, the identification unit 23 may further calculate at least one of the blue light intensity and the red light intensity as the subtraction result by subtracting the calculated infrared light intensity from at least one of the output value of the first light-receiving element 31B and the output value of the third light-receiving element 31R.

[0063] In other words, as shown in the first row of Figure 7, the outputs of the first photodetector 31B, the second photodetector 31G, and the third photodetector 31R include components (B, G, or R) due to the corresponding visible light intensity, as well as a component (IR) due to the infrared light intensity. However, as shown in the second row of Figure 7, the output of the fourth photodetector 31g consists only of a component (G) due to the green light intensity. Therefore, by subtracting the output value of the fourth photodetector 31g from the output value of the second photodetector 31G, the infrared light intensity (IR) can be calculated, as shown in the third row of Figure 7. Furthermore, by subtracting this calculated infrared light intensity from the output values ​​of the first photodetector 31B and the third photodetector 31R, the blue light intensity (B) and the red light intensity (R) can be calculated, respectively, as shown in the fourth row of Figure 7.

[0064] In this case, when using the amount of green light for identification processing, the output value of the fourth photodetector 31g may be used as is, or the amount of green light only may be calculated and used by subtracting the amount of infrared light from the output value of the second photodetector 31G.

[0065] Similarly, if the color filter 32 of the fourth light-receiving element 31 transmits only blue light, that is, if the fourth light-receiving element 31 is a fourth light-receiving element having a color filter that transmits only blue light, the identification unit 23 may calculate the amount of infrared light as the subtraction result by subtracting the output value of the fourth light-receiving element 31 from the output value of the first light-receiving element 31B.

[0066] In this case, the identification unit 23 may further calculate at least one of the green light intensity and the red light intensity as the subtraction result by subtracting the calculated infrared light intensity from at least one of the output values ​​of the second light-receiving element 31G and the output value of the third light-receiving element 31R.

[0067] In this case, when using the amount of blue light for identification processing, the output value of the fourth light-receiving element 31 may be used as is, or the amount of blue light only may be calculated and used by subtracting the amount of infrared light from the output value of the first light-receiving element 31B.

[0068] Similarly, if the color filter 32 of the fourth light-receiving element 31 transmits only red light, that is, if the fourth light-receiving element 31 is a fourth light-receiving element having a color filter that transmits only red light, the identification unit 23 may calculate the amount of infrared light as the subtraction result by subtracting the output value of the fourth light-receiving element 31 from the output value of the third light-receiving element 31R.

[0069] In this case, the identification unit 23 may further calculate at least one of the blue light intensity and the green light intensity as a result of subtracting the calculated infrared light intensity from at least one of the output values ​​of the first light-receiving element 31B and the second light-receiving element 31G.

[0070] In this case, when using the amount of red light for identification processing, the output value of the fourth photodetector 31 may be used as is, or the amount of red light only may be calculated and used by subtracting the amount of infrared light from the output value of the third photodetector 31R.

[0071] Furthermore, the identification unit 23 may calculate the light intensity of blue light, green light, red light, and infrared light all by the subtraction process described above, or it may calculate and use only the light intensity used for the identification process by the subtraction process described above.

[0072] In other words, the identification unit 23 may identify the banknote BN to be identified based on at least one of the light intensity levels of blue light, green light, red light, and infrared light, which can be calculated as a result of the above subtraction. The identification unit 23 may also identify the banknote BN to be identified based on the light intensity levels themselves. Furthermore, the identification unit 23 may identify the banknote BN to be identified based on the ratio of at least one set of light intensity levels (for example, the ratio of green light intensity to infrared light intensity, or the ratio of red light intensity to infrared light intensity) that can be calculated as a result of the above subtraction.

[0073] 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.

[0074] In either case, the identification unit 23 may determine the authenticity and presence of the fluorescent ink on the banknote BN, for example, by whether the calculated light intensity or its evaluation value is within an acceptable range relative to the reference data.

[0075] The "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 relative to the 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 the reference data.

[0076] Next, we will explain the arrangement of the first to fourth photodetectors.

[0077] The arrangement of the first to fourth photodetectors is not particularly limited, but as shown in Figures 2 and 4, the first to fourth photodetectors may be arranged in two rows.

[0078] More specifically, the first light-receiving element 31B, the second light-receiving element 31G, and the third light-receiving element 31R are arranged in a row along a first reference line L1 parallel to the Y direction (main scanning direction), and the fourth light-receiving element 31 may be arranged in a row along a second reference line L2 parallel to the Y direction (main scanning direction) and positioned offset from the first reference line L1 in the X direction (sub-scanning direction). This makes it possible to construct the first to third light-receiving elements from a line sensor equipped with a general RGB color filter. Furthermore, by arranging the fourth light-receiving element 31, which is equipped with a color filter 32 that transmits only specific monochromatic light, which may require a different manufacturing process than color filters 32B, 32G, and 32R, in a separate row, the line sensor including the fourth light-receiving element 31 can be manufactured more easily.

[0079] Furthermore, as shown in the first to fourth rows of Figure 8, the first to fourth light-receiving elements may be arranged in a single row.

[0080] In other words, the first light-receiving element 31B, the second light-receiving element 31G, the third light-receiving element 31R, and the fourth light-receiving element 31 may be arranged in a single row in the Y direction (main scanning direction).

[0081] Furthermore, as shown in Figure 9, the first light-receiving element 31B, the second light-receiving element 31G, the third light-receiving element 31R, and the fourth light-receiving element 31 may be arranged in a 2x2 configuration per pixel.

[0082] Furthermore, as shown in Figure 10, the first light-receiving element 31B, the second light-receiving element 31G, the third light-receiving element 31R, and the fourth light-receiving element 31 may be arranged in four rows per pixel.

[0083] In either case, the light-receiving unit 13 may include a plurality of pixels 30 arranged in a row in the Y direction (main scanning direction), and each pixel 30 may be composed of a first to fourth light-receiving element.

[0084] In the case where the first to third photodetectors and the fourth photodetector are arranged in two rows, Figures 2 and 4 show an example where the fourth photodetector 31 is positioned in the Y direction (main scanning direction) at a position corresponding to each of the first to third photodetectors, and the output resolution of the fourth photodetector 31 is three times that of each of the first to third photodetectors. However, it is sufficient to provide at least one fourth photodetector 31 for each of the first to third photodetectors. That is, at least one fourth photodetector 31 may be provided for each pixel 30.

[0085] Furthermore, when multiple fourth light-receiving elements 31 are provided for the first to third light-receiving elements (each pixel 30), the output value of the fourth light-receiving element 31 used in the subtraction process described above may be the output value of only one of the fourth light-receiving elements 31, or it may be a representative value (for example, the average value) of the output values ​​of multiple fourth light-receiving elements 31.

[0086] If the total number of fourth light-receiving elements 31 constituting one pixel 30 is less than the total number of first to third light-receiving elements constituting that pixel 30, the light-receiving area of ​​each fourth light-receiving element 31 may be substantially the same as the light-receiving area of ​​each of the first to third light-receiving elements, or it may be larger than the light-receiving area of ​​each of the first to third light-receiving elements. In the latter case, the output value of each fourth light-receiving element 31 may be divided by the ratio of the light-receiving area of ​​each of the first to third light-receiving elements to the light-receiving area of ​​each fourth light-receiving element 31, and the result of this division may be used in the subtraction process described above.

[0087] Furthermore, a light-receiving element (image sensor) refers to 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, which 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).

[0088] Next, the operation of the paper sheet identification device 1 according to this embodiment will be explained using Figure 11.

[0089] As shown in Figure 11, first, the light source 11 irradiates the banknote BN to be identified with light of at least a specific wavelength (step S11).

[0090] 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).

[0091] The light-receiving unit 13 includes 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, a third light-receiving element 31R having a color filter 32R that transmits red light and infrared light, and a fourth light-receiving element 31 having a color filter 32 that transmits only one type of light from among blue light, green light, red light, and infrared light (see Figures 2 to 5 and 8 to 10).

[0092] 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.

[0093] In step S13, the identification unit 23 may perform the subtraction process described above and use the result of the subtraction to identify the banknote BN.

[0094] The identification unit 23 may also function by executing a corresponding program by the control unit, which will be described later.

[0095] (Embodiment 2) This embodiment describes the case in which photoluminescence emitted from the banknote BN to be identified is detected.

[0096] 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.

[0097] First, in this embodiment, we will describe the genuine banknote that is compared with the banknote to be identified. As shown in Figures 12 and 13, the genuine banknote has fluorescent ink, which is the subject of authenticity determination, printed in a predetermined area R.

[0098] 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.

[0099] On the other hand, this special fluorescent ink does not emit light when irradiated with visible light and transmits visible light, so it is invisible to the human eye in situations where visible light is irradiated, such as under natural light or general artificial lighting (see Figure 12). 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 13), 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.

[0100] 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.

[0101] 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, the light receiving unit 13 receives fluorescence emitted from the banknote BN to be identified when irradiated with ultraviolet light, and outputs a fluorescence detection signal as a photodetection signal, and the identification unit 23 uses the 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 fluorescence emitted from the banknote BN to be identified.

[0102] Furthermore, the identification unit 23 identifies the banknote BN to be identified based on 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 compared to standard data regarding the visible light fluorescence emission amount and infrared light fluorescence emission amount of a genuine banknote. Therefore, it is 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.

[0103] Note that "fluorescence emission amount" is a value that indicates the intensity (brightness) of the fluorescence in question.

[0104] 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.

[0105] 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.

[0106] In this embodiment, the visible light fluorescence emission amount and infrared light fluorescence emission amount of the banknote BN to be identified correspond to the visible light intensity (blue light intensity, green light intensity, and / or red light intensity) and infrared light intensity, respectively, obtained by the subtraction process described in Embodiment 1. That is, the visible light fluorescence emission amount and infrared light fluorescence emission amount of the banknote BN to be identified can be calculated by a subtraction process using the output values ​​of the first to fourth 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 subtracting the fluorescence detection signal obtained when fluorescence emitted from the banknote BN to be identified, which has been irradiated with ultraviolet light, is received by 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 reference data.

[0107] In this embodiment, the "reference data" 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 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 reference data.

[0108] The reference data may include the ratio of the visible light fluorescence emission amount to the infrared light fluorescence emission amount of a genuine banknote (BN). 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 relative to the ratio included in the reference data. This allows for more accurate determination of the authenticity of the special fluorescent ink.

[0109] 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.

[0110] When using fluorescence emission ratio, the reference data may include upper and lower limits for the fluorescence emission ratio that is acceptable for genuine banknotes. 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 reference data.

[0111] 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.

[0112] 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 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 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.

[0113] More specifically, the light receiving unit 13 receives green fluorescence as visible light fluorescence and outputs a green fluorescence detection signal, the 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 reference data.

[0114] Furthermore, the light receiving unit 13 receives red fluorescence as visible light fluorescence and outputs a red fluorescence detection signal, the 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 reference data.

[0115] Furthermore, the light-receiving unit 13 receives blue fluorescence as visible light fluorescence and outputs a blue fluorescence detection signal, the reference data relates to the amount of blue 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 blue fluorescence emission and the amount of infrared fluorescence emission of the banknote to be identified are within an acceptable range relative to the reference data.

[0116] The special fluorescent ink may have a fluorescence spectrum that peaks in the infrared region or in the near-infrared region.

[0117] Thus, the light-receiving unit 13 receives near-infrared fluorescence as infrared fluorescence and outputs a near-infrared fluorescence detection signal. The 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 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.

[0118] Next, the operation of the paper sheet identification device according to this embodiment will be explained using Figure 14.

[0119] As shown in Figure 14, first, the light source 11 irradiates the banknote BN to be identified with at least ultraviolet light (step S21).

[0120] Next, the light-receiving unit 13 receives fluorescence emitted from the banknote BN to be identified, which has been irradiated with ultraviolet light, and outputs a fluorescence detection signal (step S22).

[0121] The light-receiving unit 13, as in Embodiment 1, includes 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, a third light-receiving element 31R having a color filter 32R that transmits red light and infrared light, and a fourth light-receiving element 31 having a color filter 32 that transmits only one type of light from among blue light, green light, red light, and infrared light (see Figures 2 to 5 and 8 to 10).

[0122] Subsequently, the identification unit 23 uses the 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 compared to reference data regarding the visible light fluorescence emission amount and infrared light fluorescence emission amount of a genuine banknote (step S23), and the operation of the paper sheet identification device according to this embodiment ends.

[0123] 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.

[0124] (Embodiment 3) The paper sheet processing device according to this embodiment may have, for example, the configuration shown in Figure 15. The paper sheet processing device 300 shown in Figure 15 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 15) that performs banknote identification processing, a hopper 301 on which a plurality of banknotes to be processed are placed in a stacked state, two reject units 302 that discharge rejected banknotes such as counterfeit bills and bills of uncertain authenticity that are fed from the hopper 301 into the housing 304, an operation unit 303 for inputting instructions from the operator, four stacking units 306a to 306d for classifying and stacking banknotes whose denomination, authenticity, and condition have been identified within the housing 304, and a display unit 305 for displaying information such as the banknote identification counting results and the stacking status of each stacking unit 306a to 306d. Based on the results of the paper sheet identification device's determination of whether a banknote is genuine or damaged, genuine banknotes are stored in storage units 306a to 306c, and damaged banknotes are stored in storage unit 306d. The method for distributing banknotes to storage units 306a to 306d can be set arbitrarily.

[0125] Next, the configuration of the imaging unit, which is the main part of the paper sheet identification device according to this embodiment, will be described using Figure 16. As shown in Figure 16, 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.

[0126] As shown in Figure 16, 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.

[0127] 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.

[0128] 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.

[0129] 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.

[0130] 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 16 (main scanning direction, Y direction), and a plurality of LED elements (not shown) provided at both ends (or one end) of the light guide.

[0131] 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.

[0132] 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.

[0133] As shown in Figures 2 and 4, each light-receiving unit 113, 123 is equipped with a plurality of pixels 30 arranged in a row in the main scanning direction (the direction perpendicular to the transport direction of the banknote BN, the Y direction), and each pixel 30 is equipped with a row of first light-receiving elements 31B, second light-receiving elements 31G and third light-receiving elements 31R and a row of fourth light-receiving elements 31.

[0134] Figure 16 shows a case where one focusing lens forms an image over the range of two rows of photodetectors, but it is also possible to provide a focusing lens that forms an image over the range of each row of photodetectors. In other words, two rows of focusing lenses may be arranged so that they face each of the two rows of photodetectors.

[0135] 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.

[0136] 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.

[0137] Next, the configuration of the paper sheet identification device according to this embodiment will be described using Figure 17. As shown in Figure 17, the paper sheet identification device 200 according to this embodiment includes a detection unit 210, a control unit 220, and a storage unit 230.

[0138] 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.

[0139] 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.

[0140] 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 (e.g., 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.

[0141] 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.

[0142] 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.

[0143] 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.

[0144] 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.

[0145] 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.

[0146] The identification unit 223 uses the optical detection signal acquired by the imaging unit 211 to identify the banknote BN.

[0147] More specifically, the identification unit 223 calculates the amount of visible fluorescence emission of a specific color (blue, green, or red) and the amount of infrared fluorescence emission of the banknote to be identified by performing the subtraction process described above using the fluorescence detection signal corresponding to the identification target area of ​​the fluorescence image. This identification target area may be set according to the denomination of the banknote.

[0148] The identification unit 223 then determines the authenticity of the banknote BN by checking whether the calculated visible light fluorescence emission amount and infrared light fluorescence emission amount of the banknote BN to be identified are within an acceptable range compared to standard data regarding the visible light fluorescence emission amount and infrared light fluorescence emission amount of a genuine banknote.

[0149] (Variation 1) 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.

[0150] (Modification 2) 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, and identification processing can be performed using this phosphorescence detection signal in the same way as with the fluorescence detection signal. For example, the banknote to be identified can be identified by 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.

[0151] 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]

[0152] As described above, this disclosure is a useful technique for simultaneously obtaining visible and infrared data without using filter configurations that are difficult to manufacture. [Explanation of Symbols]

[0153] 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, 31IR, 31g: Photodetector 32, 32B, 32G, 32R, 32IR, 32g: Color filters 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: Paper money

Claims

1. A light source capable of irradiating the paper sheets to be identified with light of a specific wavelength, A light receiving unit receives light arriving from the paper sheets to be identified based on the light from the light source and outputs a light detection signal. The system includes an identification unit that identifies the paper sheets to be identified using the light detection signal output from the light receiving unit, The light-receiving unit comprises: 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; a third light-receiving element having a color filter that transmits red light and infrared light; and a fourth light-receiving element having a color filter that transmits only one of the following types of light: blue light, green light, red light, and infrared light. A paper sheet identification device characterized by the following features.

2. The identification unit subtracts the output value of the fourth light-receiving element from at least one of the output values ​​of the first light-receiving element, the second light-receiving element, and the third light-receiving element, and uses the result of this subtraction to identify the paper sheets to be identified. The paper sheet identification device according to claim 1, characterized in that it is a paper sheet identification device.

3. The color filter of the fourth light-receiving element transmits only infrared light. The identification unit subtracts the output value of the fourth light-receiving element from at least one of the output values ​​of the first light-receiving element, the second light-receiving element, and the third light-receiving element to calculate at least one of the blue light intensity, green light intensity, and red light intensity as the subtraction result. The paper sheet identification device according to claim 2, characterized in that it is a paper sheet identification device.

4. The color filter of the fourth light-receiving element transmits only blue light. The identification unit calculates the amount of infrared light as the subtraction result by subtracting the output value of the fourth light-receiving element from the output value of the first light-receiving element. The paper sheet identification device according to claim 2, characterized in that it is a paper sheet identification device.

5. The identification unit further calculates at least one of the green light intensity and the red light intensity as the subtraction result by subtracting the amount of infrared light from at least one of the output value of the second light receiving element and the output value of the third light receiving element. The paper sheet identification device according to claim 4, characterized in that it is a paper sheet identification device.

6. The color filter of the fourth light-receiving element transmits only green light. The identification unit calculates the amount of infrared light as the subtraction result by subtracting the output value of the fourth light-receiving element from the output value of the second light-receiving element. The paper sheet identification device according to claim 2, characterized in that it is a paper sheet identification device.

7. The identification unit further calculates at least one of the blue light intensity and the red light intensity as the subtraction result by subtracting the amount of infrared light from at least one of the output value of the first light receiving element and the output value of the third light receiving element. The paper sheet identification device according to claim 6, characterized in that it is a paper sheet identification device.

8. The color filter of the fourth light-receiving element transmits only red light. The identification unit calculates the amount of infrared light as the subtraction result by subtracting the output value of the fourth light-receiving element from the output value of the third light-receiving element. The paper sheet identification device according to claim 2, characterized in that it is a paper sheet identification device.

9. The identification unit further calculates at least one of the blue light intensity and the green light intensity as the subtraction result by subtracting the amount of infrared light from at least one of the output value of the first light receiving element and the output value of the second light receiving element. The paper sheet identification device according to claim 8, characterized in that it is a paper sheet identification device.

10. The first, second, third, and fourth light-receiving elements are arranged in a single row in the main scanning direction. A paper sheet identification device according to any one of features 1 to 9.

11. The first light-receiving element, the second light-receiving element, and the third light-receiving element are arranged in a row along a first reference line parallel to the main scanning direction. The fourth light-receiving element is arranged in a row along a second reference line that is parallel to the main scanning direction and is positioned offset from the first reference line in the sub-scanning direction. A paper sheet identification device according to any one of features 1 to 9.

12. The light of the specific wavelength emitted by the light source is ultraviolet light. The light-receiving unit receives photoluminescence emitted from the paper sheets to be identified, which have been irradiated with ultraviolet light, and outputs a photoluminescence detection signal as the light detection signal. The identification unit uses the photoluminescence detection signal output from the light receiving unit to identify the paper sheets to be identified. A paper sheet identification device according to any one of claims 1 to 11.

13. The identification unit identifies the paper sheets to be identified based on whether the visible light photoluminescence emission amount and infrared light photoluminescence emission amount of the paper sheets to be identified are within an acceptable range compared to reference data regarding the visible light photoluminescence emission amount and infrared light photoluminescence emission amount of genuine paper sheets. The paper sheet identification device according to claim 12, characterized in that it is a paper sheet identification device.

14. The aforementioned 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 reference data. The paper sheet identification device according to claim 13, characterized in that it is a paper sheet identification device.

15. 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 aforementioned reference data pertains to the photoluminescence emission amount of at least one color and the photoluminescence 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 relative to the reference data. The paper sheet identification device according to claim 13 or 14, characterized in that it is a paper sheet identification device.

16. The light-receiving unit receives green photoluminescence as visible light photoluminescence and outputs a green photoluminescence detection signal. The aforementioned reference data 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 reference data. The paper sheet identification device according to claim 15, characterized in that it is a paper sheet identification device.

17. The light-receiving unit receives red photoluminescence as visible light photoluminescence and outputs a red photoluminescence detection signal. The aforementioned reference data pertains to the photoluminescence emission amount of red 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 red photoluminescence emission and infrared photoluminescence emission of the paper sheets to be identified are within an acceptable range relative to the reference data. The paper sheet identification device according to claim 15, characterized in that it is a paper sheet identification device.

18. The light-receiving unit receives blue photoluminescence as visible light photoluminescence and outputs a blue photoluminescence detection signal. The aforementioned reference data 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 the amount of infrared photoluminescence emission of the paper sheets to be identified are within an acceptable range relative to the reference data. The paper sheet identification device according to claim 15, characterized in that it is a paper sheet identification device.

19. The light-receiving unit receives near-infrared photoluminescence as infrared photoluminescence and outputs a near-infrared photoluminescence detection signal. The aforementioned reference data 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 reference data. A paper sheet identification device according to any one of claims 13 to 18.

20. A paper sheet processing apparatus characterized by comprising a paper sheet identification device according to any one of claims 1 to 19.

21. The steps include irradiating the paper sheets to be identified with light of a specific wavelength from a light source, The steps include: receiving light from the paper sheets to be identified based on the light from the light source and outputting a light detection signal; The system includes the step of identifying the paper sheets to be identified using the light detection signal output from the light receiving unit, The light-receiving unit comprises: 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; a third light-receiving element having a color filter that transmits red light and infrared light; and a fourth light-receiving element having a color filter that transmits only one of the following types of light: blue light, green light, red light, and infrared light. A method for identifying paper sheets, characterized by the features described herein.

22. A process in which light of a specific wavelength is irradiated onto the paper sheets to be identified from a light source, A process that receives light from the paper sheets to be identified based on the light from the light source and outputs a light detection signal, A process for identifying the paper sheets to be identified using the light detection signal output from the light receiving unit, This is to be performed by the paper sheet identification device. The light-receiving unit comprises: 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; a third light-receiving element having a color filter that transmits red light and infrared light; and a fourth light-receiving element having a color filter that transmits only one of the following types of light: blue light, green light, red light, and infrared light. A paper sheet identification program characterized by the following features.

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