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

Abstract

This 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 identify highly secure paper sheets using photoluminescent compounds. [Solution] A paper sheet identification device comprising: a light source capable of irradiating the paper sheets to be identified with at least ultraviolet light; a light receiving unit that receives photoluminescence emitted from the paper sheets to be identified irradiated with ultraviolet light and outputs a photoluminescence detection signal; and an identification unit that uses the photoluminescence detection signal output from the light receiving unit to identify the paper sheets to be identified based on whether the amount of visible light photoluminescence emission and infrared light photoluminescence emission of the paper sheets to be identified are within an acceptable range with respect to reference data regarding the amount of visible light photoluminescence emission and infrared light photoluminescence emission of genuine paper sheets.

Description

[Technical Field]

[0001] This disclosure relates to a paper sheet identification device, a paper sheet processing device, a paper sheet identification method, and a paper sheet identification program. [Background technology]

[0002] Traditionally, photoluminescent compounds have been known as security elements attached to paper materials such as banknotes. Photoluminescent compounds are excited by ultraviolet light, etc., and produce fluorescence or phosphorescence. Methods for detecting these properties are known, for example, those described in the following literature.

[0003] Patent Document 1 describes a device that acquires IR information in addition to visible color information (RGB). It acquires visible color information by simultaneously irradiating with non-visible light (infrared / ultraviolet light) when visible light is irradiated, and then acquiring IR information as phosphorescence after all lights are turned off. This allows for the acquisition of both visible and non-visible color information with a small number of illumination cycles.

[0004] 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]

[0005] [Patent Document 1] Patent No. 6469370 [Patent Document 2] Patent No. 7473677 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, there is a demand for security elements that utilize photoluminescent compounds that are even more secure and can be mechanically identified.

[0007] 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 identify highly secure paper sheets using photoluminescent compounds. [Means for solving the problem]

[0008] 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 at least ultraviolet light; a light receiving unit that receives photoluminescence emitted from the paper sheet to be identified irradiated with ultraviolet light and outputs a photoluminescence detection signal; and an identification unit that uses the photoluminescence detection signal output from the light receiving unit to 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.

[0009] (2) In the paper sheet identification device described in (1) 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.

[0010] (3) In the paper sheet identification device described in (1) or (2) above, the light receiving unit may receive photoluminescence of at least one color from blue, green, and red as visible light photoluminescence and output a photoluminescence detection signal of the at least one color, the reference data may relate to the amount of photoluminescence emission of the at least one color and the amount of photoluminescence emission of infrared light, and the identification unit may identify the paper sheet to be identified based on whether the amount of photoluminescence emission of the at least one color and the amount of photoluminescence emission of infrared light of the paper sheet to be identified are within an acceptable range with respect to the reference data.

[0011] (4) In the paper sheet identification device described in (3) above, the light receiving unit may receive green photoluminescence as visible light photoluminescence and output a green photoluminescence detection signal, the reference data may relate to the amount of green photoluminescence emission and the amount of infrared photoluminescence emission, and the identification unit may identify the paper sheet to be identified based on whether the amount of green photoluminescence emission and the amount of infrared photoluminescence emission of the paper sheet to be identified are within an acceptable range with respect to the reference data.

[0012] (5) In the paper sheet identification device described in (3) above, the light receiving unit may receive red photoluminescence as visible light photoluminescence and output a red photoluminescence detection signal, the reference data may relate to the amount of red photoluminescence emission and the amount of infrared photoluminescence emission, and the identification unit may identify the paper sheet to be identified based on whether the amount of red photoluminescence emission and the amount of infrared photoluminescence emission of the paper sheet to be identified are within an acceptable range with respect to the reference data.

[0013] (6) In the paper sheet identification device described in (3) 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 amount of blue photoluminescence emission and the amount of infrared photoluminescence emission, and the identification unit may identify the paper sheet to be identified based on whether the amount of blue photoluminescence emission and the amount of infrared photoluminescence emission of the paper sheet to be identified are within an acceptable range with respect to the reference data.

[0014] (7) In the paper sheet identification device described in any of (1) to (6) above, the light receiving unit may receive near-infrared photoluminescence as infrared photoluminescence and output a near-infrared photoluminescence detection signal, the reference data may relate to the amount of visible light photoluminescence emission and the amount of near-infrared photoluminescence emission, and the identification unit may identify the paper sheet to be identified based on whether the amount of visible light photoluminescence emission and the amount of near-infrared photoluminescence emission of the paper sheet to be identified are within an acceptable range with respect to the reference data.

[0015] (8) In the paper sheet identification device described in any of (1) to (7) above, the light receiving unit may include a first light receiving element having a color filter that transmits blue light and infrared light, a second light receiving element having a color filter that transmits green light and infrared light, and a third light receiving element having a color filter that transmits red light and infrared light.

[0016] (9) In the paper sheet discrimination device according to (8) above, the discrimination unit corrects the photoluminescence detection signal obtained by receiving, by the light receiving unit, the photoluminescence emitted from the paper sheet to be discriminated irradiated with the ultraviolet light, by using a correction value based on the photoluminescence detection signals obtained by separately receiving, by the light receiving unit, the photoluminescence emitted from the visible photoluminescence ink that emits photoluminescence in a visible specific color and the photoluminescence emitted from the infrared photoluminescence ink that emits photoluminescence with infrared light. Thus, the amount of photoluminescence emitted in the visible specific color and the amount of photoluminescence emitted with infrared light of the paper sheet to be discriminated are calculated, and the paper sheet to be discriminated may be discriminated based on whether or not the amount of photoluminescence emitted in the visible specific color and the amount of photoluminescence emitted with infrared light are within an allowable range with respect to the reference data.

[0017] (10) In the paper sheet discrimination device according to (9) above, the correction value may be based on output values of two light receiving elements selected from the first light receiving element, the second light receiving element, and the third light receiving element.

[0018] (11) In the paper sheet discrimination device according to (10) above, one of the two light receiving elements may be a light receiving element that outputs a maximum value when receiving the photoluminescence emitted from the visible photoluminescence ink among the first light receiving element, the second light receiving element, and the third light receiving element, and the other of the two light receiving elements may be a light receiving element that outputs a maximum value when receiving the photoluminescence emitted from the infrared photoluminescence ink among the first light receiving element, the second light receiving element, and the third light receiving element.

[0019] (12) In the paper sheet discrimination device according to (11) above, the correction value may be based on a 2x2 matrix composed of output values obtained by separately receiving, by the two light receiving elements, the photoluminescence emitted from the visible photoluminescence ink and the photoluminescence emitted from the infrared photoluminescence ink.

[0020] (13) In the paper sheet discrimination device according to (12) above, the correction value may be based on a matrix obtained by normalizing the matrix.

[0021] (14) In the paper sheet discrimination device according to (12) or (13) above, the correction value may be based on the inverse matrix of the matrix.

[0022] (15) In the paper sheet discrimination device according to (9) above, when a light receiving element that outputs a maximum value when receiving the photoluminescence emitted by the visible photoluminescence ink and a light receiving element that outputs a maximum value when receiving the photoluminescence emitted by the infrared photoluminescence ink are the same, that light receiving element is defined as the light receiving element P. When the output values of the first light receiving element, the second light receiving element, and the third light receiving element when the photoluminescence emitted by the visible photoluminescence ink is received by the light receiving unit are a, b, and c respectively, and the output values of the first light receiving element, the second light receiving element, and the third light receiving element when the photoluminescence emitted by the infrared photoluminescence ink is received by the light receiving unit are d, e, and f respectively, the correction value may be based on the output value of the light receiving element P and the combination of addition values that shows the largest difference among (d + e) - (a + b), (e + f) - (b + c), (d + f) - (a + c), and (d + e + f) - (a + b + c).

[0023] (16) In the paper sheet discrimination device according to (15) above, the correction value may be based on a 2x2 matrix composed of the output value obtained by separately receiving the photoluminescence emitted by the visible photoluminescence ink and the photoluminescence emitted by the infrared photoluminescence ink with the light receiving element P and the combination of addition values that shows the largest difference.

[0024] (17) In the paper sheet discrimination device according to (16) above, the correction value may be based on a matrix obtained by normalizing the matrix.

[0025] (18) In the paper sheet identification device described in (16) or (17) above, the correction value may be based on the inverse matrix of the matrix.

[0026] (19) In the paper sheet identification device described in any of (1) to (7) above, the light receiving unit may include a first light receiving element having a color filter that transmits blue light, a second light receiving element having a color filter that transmits green light, a third light receiving element having a color filter that transmits red light, and a fourth light receiving element having a color filter that transmits infrared light.

[0027] (20) Furthermore, a paper sheet processing device according to a second aspect of the present disclosure is equipped with a paper sheet identification device as described in any of (1) to (19) above.

[0028] (21) A paper sheet identification method according to a third aspect of the present disclosure comprises the steps of: irradiating a paper sheet to be identified with at least ultraviolet light from a light source; receiving photoluminescence emitted from the paper sheet to be identified that has been irradiated with ultraviolet light with a light receiving unit and outputting a photoluminescence detection signal; and using the photoluminescence detection signal output from the light receiving unit to 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.

[0029] (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 the paper sheet to be identified with at least ultraviolet light from a light source; receiving the photoluminescence emitted from the paper sheet to be identified that has been irradiated with ultraviolet light with a light receiving unit and outputting a photoluminescence detection signal; and using the photoluminescence detection signal output from the light receiving unit to identify the paper sheet to be identified based on whether the visible light photoluminescence emission amount and infrared light photoluminescence emission amount of the paper sheet to be identified are within an acceptable range with respect to reference data regarding the visible light photoluminescence emission amount and infrared light photoluminescence emission amount of a genuine paper sheet. [Effects of the Invention]

[0030] 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 identify highly secure paper sheets using photoluminescent compounds. [Brief explanation of the drawing]

[0031] [Figure 1] This is a schematic plan view of an example of a genuine banknote, showing its appearance under visible light illumination. [Figure 2] This is a schematic plan view of an example of genuine banknote, showing its appearance under ultraviolet light irradiation. [Figure 3] 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 4] This is a flowchart illustrating an example of the operation of the paper sheet identification device according to Embodiment 1. [Figure 5] This is a schematic perspective view illustrating an example of the configuration of the light-receiving unit of the paper sheet identification device according to Embodiment 2. [Figure 6] This is a schematic diagram showing the wavelength characteristics of the color filter of the light-receiving section of the paper sheet identification device according to Embodiment 2. [Figure 7]This is a schematic plan view showing an example of a banknote to be used for authenticity determination by fluorescence measurement. [Figure 8] This is a schematic perspective view illustrating an example of the configuration of the light-receiving unit of the paper sheet identification device according to Embodiment 3. [Figure 9] This is a schematic diagram showing the wavelength characteristics of the color filter of the light-receiving section of the paper sheet identification device according to Embodiment 3. [Figure 10] This is a schematic perspective view showing the external appearance of an example of a paper sheet processing device according to Embodiment 4. [Figure 11] 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 4. [Figure 12] This is a block diagram illustrating an example of the configuration of a paper sheet identification device according to Embodiment 4. [Modes for carrying out the invention]

[0032] 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.

[0033] Furthermore, in this specification, photoluminescence is a concept that encompasses fluorescence and phosphorescence, but in the following, this disclosure will be explained using fluorescence (photoluminescence that can be detected during excitation light irradiation) as an example of photoluminescence. Specifically, in the following, we will explain the cases in which "photoluminescence," "photoluminescence detection signal," "photoluminescence emission amount," "photoluminescent ink," "visible photoluminescent ink," and "infrared photoluminescent ink" are "fluorescence," "fluorescence detection signal," "fluorescence emission amount," "fluorescent ink," "visible fluorescent ink," and "infrared fluorescent ink," respectively.

[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 processing device according 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) First, let's describe the genuine banknotes that are compared to the banknote to be identified. As shown in Figures 1 and 2, genuine banknotes have fluorescent ink printed in a predetermined area R that is the subject of authenticity determination.

[0038] 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.

[0039] 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 present, such as under natural light or general artificial lighting (see Figure 1). 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 2), 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.

[0040] 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.

[0041] Next, the configuration of the paper sheet identification device according to this embodiment will be described using Figure 3.

[0042] As shown in Figure 3, the paper sheet identification device 1 according to this embodiment detects fluorescence emitted from the banknote BN to be identified, and comprises a light source 11 capable of irradiating the banknote BN to be identified with at least ultraviolet light, a light receiving unit 13 that receives fluorescence emitted from the banknote BN to be identified irradiated with ultraviolet light and outputs a fluorescence detection signal, and an identification unit 23 that identifies the banknote BN to be identified using the fluorescence detection signal output from the light receiving unit 13.

[0043] 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.

[0044] The identification unit 23 identifies 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 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 1 can mechanically identify banknotes with high security that utilize photoluminescence compounds. Thus, the identification unit 23 may also be used to determine the authenticity of the banknote BN to be identified.

[0045] Note that "fluorescence emission amount" is a value that indicates the intensity (brightness) of the fluorescence in question.

[0046] 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.

[0047] 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.

[0048] 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 sensitive to at least the wavelength range (visible and infrared) of fluorescence emitted from the special fluorescent ink. The light-receiving unit 13 then outputs an electrical signal (which may also be a digital signal) corresponding to the amount of incident light (amount of light received). In other words, 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.

[0049] The light-receiving unit 13 may include one or more light-receiving elements, which may receive light, convert it into an electrical signal corresponding to the amount of incident light, and output it.

[0050] 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.

[0051] 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.

[0052] Thus, the light source 11 and the light receiving unit 13 may acquire an image of the entire banknote BN by continuously repeating the imaging process, with a predetermined cycle counting as one period.

[0053] 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 fluorescence 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 a reflective image and / or transmitted image of the sheet of paper.

[0054] A reflected image is an image based on light reflected by paper sheets, irradiated from a light source positioned on the same side as the light-receiving unit. A transmitted image is an image based on light transmitted through paper sheets, irradiated from a light source positioned on the opposite side of the light-receiving unit. Therefore, reflected and transmitted images are distinct from fluorescence images, which are based on fluorescence emitted from paper sheets.

[0055] 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.

[0056] Furthermore, the light-receiving unit 13 may receive light of multiple wavelength bands arriving from the banknote BN and output electrical signals (fluorescence detection 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 from each other.

[0057] The light-receiving unit 13 may receive both the visible-range fluorescent component and the infrared-range fluorescent component emitted from the banknote BN irradiated with ultraviolet light without separating them, and output a fluorescence detection signal that includes a signal value corresponding to the total light intensity of both components. In this case, the signal value corresponding to the total light intensity of both components may be corrected for spectral overlap to separate the amount of light emitted according to the visible-range fluorescent component and the amount of light emitted according to the infrared-range fluorescent component, and these separated amounts of light emitted may be used as the visible-light fluorescence emission amount and the infrared-light fluorescence emission amount of the banknote BN to be identified.

[0058] On the other hand, the light-receiving unit 13 may separate the visible-range fluorescence component and the infrared-range fluorescence component emitted from the banknote BN irradiated with ultraviolet light, receive them independently, and output signal values ​​corresponding to the light intensity of each component. In this case, these signal values ​​can be used as the visible-light fluorescence emission amount and the infrared-light fluorescence emission amount of the banknote BN to be identified, respectively, without spectral overlap correction.

[0059] The cases in which spectral overlap correction is performed and those in which it is not will be described in more detail in Embodiments 2 and 3, respectively.

[0060] Thus, the visible light fluorescence emission amount and infrared light fluorescence emission amount of the banknote BN to be identified may be obtained by correcting the fluorescence detection signal output from the light receiving unit 13 for spectral overlap, or it may be obtained without correcting the fluorescence detection signal output from the light receiving unit 13 for spectral overlap.

[0061] Spectral overlap correction is a correction value based on fluorescence detection signals obtained by separately receiving fluorescence from a light-receiving unit, specifically from the fluorescence emitted by visible fluorescent ink that fluoresces in a specific visible color and the fluorescence emitted by infrared fluorescent ink that fluoresces in infrared light. By correcting the fluorescence detection signal obtained by receiving fluorescence emitted from a banknote, the amount of fluorescence emitted in the wavelength band of the specific visible color and the amount of fluorescence emitted in the infrared region of that banknote are calculated.

[0062] 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 genuine banknotes, 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 relative to 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.

[0063] 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 paper sheets 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] The special fluorescent ink may have a fluorescence spectrum that peaks in the infrared region or in the near-infrared region.

[0072] 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.

[0073] In this specification, blue refers to light (color) with a wavelength of approximately 400 nm to 500 nm and having a peak wavelength in this wavelength range; green refers to light (color) with a wavelength of approximately 500 nm to 600 nm and having a peak wavelength in this wavelength range; and red refers to light (color) with a wavelength of approximately 600 nm to 750 nm and having a peak wavelength in this wavelength range. Furthermore, infrared light refers to light with a wavelength of approximately 750 nm or more and having a peak wavelength in that wavelength range, and near-infrared light refers to light with a wavelength of approximately 750 nm to 1500 nm and having a peak wavelength in that wavelength range.

[0074] Next, the operation of the paper sheet identification device 1 according to this embodiment will be explained using Figure 4.

[0075] As shown in Figure 4, first, the light source 11 irradiates the banknote BN to be identified with at least ultraviolet light (step S11).

[0076] 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 S12).

[0077] 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 S13), and the operation of the paper sheet identification device 1 ends.

[0078] The identification unit 23 may also function by executing a corresponding program by the control unit, which will be described later.

[0079] (Embodiment 2) In this embodiment, the case in which spectral overlap correction is performed will be described in more detail.

[0080] As shown in Figure 5, in this embodiment, the light-receiving unit 13 includes a first light-receiving element 31B having a color filter 32B, a second light-receiving element 31G having a color filter 32G, and a third light-receiving element 31R having a color filter 32R.

[0081] The light-receiving unit 13 may include a plurality of pixels 30 arranged in a row in the main scanning direction D1 (the direction perpendicular to the transport direction of the banknote BN, the Y direction), and each pixel 30 may include one first light-receiving element (image sensor) 31B, one second light-receiving element (image sensor) 31G, and one third light-receiving element (image sensor) 31R, and the first light-receiving element 31B, the second light-receiving element 31G, and the third light-receiving element 31R may be arranged in this order in a row in the main scanning direction D1.

[0082] Here, a light-receiving element (image sensor) means an element that detects (converts into an electrical signal) the intensity of light in a predetermined wavelength band, and may be configured to include a photodetector such as a photodiode, and a color filter (color resist) provided on the light-receiving surface of the photodetector that suppresses the transmission of light in wavelength bands other than the predetermined wavelength band to be detected (for example, the blue and infrared wavelength bands) (for example, the green and red wavelength bands).

[0083] As shown in Figure 5, the first light-receiving element 31B may include a photodetector 33 and a color filter 32B, the second light-receiving element 31G may include a photodetector 33 and a color filter 32G, and the third light-receiving element 31R may include a photodetector 33 and a color filter 32R.

[0084] Furthermore, as shown in Figure 6, color filter 32B transmits blue light and infrared light, color filter 32G transmits green light and infrared light, and color filter 32R transmits 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. Color filter 32B absorbs green light and red light, color filter 32G absorbs blue light and red light, and color filter 32R absorbs blue light and green light.

[0085] Therefore, the light-receiving unit 13 receives both the visible-range fluorescent component and the infrared-range fluorescent component emitted from the banknote (special fluorescent ink) together without separating them with each light-receiving element, and outputs a fluorescence detection signal that includes a signal value corresponding to the total light intensity of both components. As a result, spectral overlap correction is necessary.

[0086] In other words, the identification unit 23 uses a correction value to correct the fluorescence detection signal obtained by receiving fluorescence emitted from the banknote to be identified, which has been irradiated with ultraviolet light, with the light receiving unit 13. This corrects the fluorescence emission amount of a specific visible color and an infrared light color of the banknote to be identified, and identifies the banknote to be identified based on whether the calculated fluorescence emission amount of a specific visible color and an infrared light color is within an acceptable range relative to the reference data.

[0087] Here, the correction value is based on a fluorescence detection signal obtained by separately receiving fluorescence emitted by a visible fluorescent ink that emits fluorescence in a specific visible color and fluorescence emitted by an infrared fluorescent ink that emits fluorescence in infrared light, using the light receiving unit 13.

[0088] A visible fluorescent ink that emits fluorescence in a specific visible color may have a fluorescence spectrum that has a peak in only one of the following wavelength bands: blue, green, or red. Hereafter, this ink may simply be referred to as a specific color visible fluorescent ink. Thus, a specific color visible fluorescent ink may emit only blue, green, or red fluorescence. Furthermore, a specific color visible fluorescent ink may not emit fluorescence in wavelength bands other than the visible region, such as the infrared region.

[0089] Infrared fluorescent inks that emit fluorescence in the infrared region may have a fluorescence spectrum that has a peak only in the infrared (near-infrared) region. Hereafter, this ink may simply be referred to as infrared fluorescent ink. Furthermore, infrared fluorescent inks do not need to emit fluorescence in wavelength bands other than the infrared (near-infrared) region, such as the visible region.

[0090] The peak wavelength in the visible range of fluorescence emission from a specific color of visible fluorescent ink lies in the same wavelength band as the peak wavelength in the visible range of fluorescence emission from a special fluorescent ink printed on genuine banknotes; for example, these peak wavelengths lie in the blue, green, or red wavelength band. Similarly, the peak wavelength in the infrared range of fluorescence emission from infrared fluorescent ink lies in the same wavelength band as the peak wavelength in the infrared range of fluorescence emission from a special fluorescent ink printed on genuine banknotes; for example, these peak wavelengths lie in the near-infrared wavelength band.

[0091] Specific methods for calculating the above correction value include, for example, (A) a method of calculation based on the output values ​​of only two photodetectors, and (B) a method of calculation based on the sum of the output value of one photodetector and the output values ​​of at least two photodetectors.

[0092] In other words, (A) the above correction value may be based on the output values ​​of two photodetectors selected from the first photodetector 31B, the second photodetector 31G, and the third photodetector 31R. This allows spectral overlap correction to be performed using the output values ​​of these two photodetectors, making it easier to perform calculations related to the correction.

[0093] In this case, one of the two photodetectors may be a photodetector that outputs a maximum value when it receives fluorescence emitted from a specific color of visible fluorescent ink, among the first photodetector 31B, the second photodetector 31G, and the third photodetector 31R, and the other of the two photodetectors may be a photodetector that outputs a maximum value when it receives fluorescence emitted from infrared fluorescent ink, among the first photodetector 31B, the second photodetector 31G, and the third photodetector 31R. This improves the accuracy of spectral overlap correction. In other words, it becomes possible to more accurately separate the amount of light emitted corresponding to the visible region fluorescence component from the amount of light emitted corresponding to the infrared region fluorescence component from the fluorescence detection signal obtained by receiving fluorescence emitted from a special fluorescent ink.

[0094] The above correction value may be based on a 2x2 matrix composed of output values ​​obtained by receiving the fluorescence emitted by a specific color of visible fluorescent ink and the fluorescence emitted by an infrared fluorescent ink individually using the two photodetectors.

[0095] The above correction values ​​may be based on a normalized version of the above matrix. In the normalized version of the above matrix, the diagonal elements are 1.

[0096] The above correction value may be based on the inverse matrix of the above matrix (which may be normalized or unnormalized).

[0097] Specifically, before shipment or during maintenance of the paper sheet identification device 1, the fluorescence emitted from a specific color of visible fluorescent ink and the fluorescence emitted from an infrared fluorescent ink are individually received by the light receiving unit 13, and the reference emission amount (output value) of each fluorescent ink is measured, resulting in output values ​​such as those shown in Table 1 below. Here, it is assumed that, for example, green visible fluorescent ink is used as the specific color of visible fluorescent ink.

[0098] [Table 1]

[0099] CH_B represents the output value of the first photodetector 31B, CH_G represents the output value of the second photodetector 31G, and CH_R represents the output value of the third photodetector 31R. Furthermore, the measurement result for the green visible fluorescent ink is assumed to be at its maximum value b, and the measurement result for the infrared fluorescent ink is assumed to be at its maximum value f. In other words, we use a photodetector (second photodetector 31G) whose measurement result for the green visible fluorescent ink is greater than that for the infrared fluorescent ink, and a photodetector (third photodetector 31R) whose measurement result for the infrared fluorescent ink is greater than that for the green visible fluorescent ink. As a result, the following equation (1) holds.

[0100]

number

[0101] Green_INK represents the amount of light emitted (fluorescence signal) of the corrected green visible fluorescent ink, and IR_INK represents the amount of light emitted (fluorescence signal) of the corrected infrared fluorescent ink.

[0102] When matrix A in equation (1) above is normalized, the following relationship (2) holds.

[0103]

number

[0104] Transforming equation (2) above yields the relationship shown in equation (3) below.

[0105]

number

[0106] Then, as shown in equation (3) above, the inverse matrix B is applied to the fluorescence detection signal obtained by receiving light in the light receiving unit 13. -1 By performing a multiplication operation, it is possible to calculate (separate) Green_INK, i.e., the amount of light emitted by the corrected green visible fluorescent ink, and IR_INK, i.e., the amount of light emitted by the corrected infrared fluorescent ink.

[0107] This inverse matrix B -1 This value may be stored in the memory unit as a correction value.

[0108] Similarly, when using blue or red visible fluorescent ink as a specific color, it is possible to separate the luminescence of the corrected blue or red visible fluorescent ink (Blue_INK or Red_INK) from the luminescence of the corrected infrared fluorescent ink (IR_INK).

[0109] Next, we will explain method (B) above. This method can be used when method (A) above is not available.

[0110] In other words, if the light-receiving element that outputs the maximum value when it receives fluorescence emitted from a specific color of visible fluorescent ink is the same as the light-receiving element that outputs the maximum value when it receives fluorescence emitted from infrared fluorescent ink, then that light-receiving element is denoted as light-receiving element P. Furthermore, when the light-receiving unit 13 receives fluorescence emitted from a specific color of visible fluorescent ink, the output values ​​of the first light-receiving element 31B, the second light-receiving element 31G, and the third light-receiving element 31R are denoted as a, b, and c, respectively, and when the light-receiving unit 13 receives fluorescence emitted from infrared fluorescent ink, the output values ​​of the first light-receiving element 31B, the second light-receiving element 31G, and the third light-receiving element 31R are denoted as d, e, and f, respectively. In this case, the correction value may be based on the combination of the sum of the output values ​​a to f, which is the largest difference between the output value of the photodetector P and the sum of the output values ​​a to f, i.e., (d+e)-(a+b), (e+f)-(b+c), (d+f)-(a+c), and (d+e+f)-(a+b+c). This allows spectral overlap correction to be performed even when the method described in (A) above is not available.

[0111] The above correction value may be based on a 2x2 matrix consisting of the output values ​​obtained by individually receiving the fluorescence emitted by a visible fluorescent ink of a specific color and the fluorescence emitted by an infrared fluorescent ink with a photodetector P, and the sum of the values ​​showing the largest difference.

[0112] The above correction values ​​may be based on a normalized matrix. In the normalized matrix, the diagonal elements are 1.

[0113] The above correction value may be based on the inverse matrix of the above matrix (which may be normalized or unnormalized).

[0114] Specifically, let's assume that the output values ​​shown in Table 2 below were obtained.

[0115] [Table 2]

[0116] However, here we assume that a red visible fluorescent ink is used as the specific color visible fluorescent ink, and that the measurement result for the specific color visible fluorescent ink is that c is the maximum value, and the measurement result for the infrared fluorescent ink is that f is the maximum value, and in both cases the output value of the third photodetector 31R is the maximum value. In other words, the third photodetector 31R is defined as photodetector P.

[0117] In this case, as shown in Table 2, the output values ​​of multiple photodetectors are added together (B+R, G+R, B+R, B+G+R), and the difference between the output value of the red visible fluorescent ink and the output value of the infrared fluorescent ink at each added value is calculated (far right column of Table 2). Then, a correction value is calculated using the combination of photodetectors with the largest difference (for example, the first photodetector 31B and the second photodetector 31G) and the output value of the photodetector P (i.e., the third photodetector 31R) that showed the maximum value.

[0118] As a result, equation (4) below holds true.

[0119]

number

[0120] Red_INK represents the amount of light emitted (fluorescence signal) of the corrected red visible fluorescent ink, and IR_INK represents the amount of light emitted (fluorescence signal) of the corrected infrared fluorescent ink.

[0121] When the matrix C in equation (4) above is normalized, the relationship in equation (5) below holds.

[0122]

number

[0123] Transforming equation (5) above yields the relationship shown in equation (6) below.

[0124]

number

[0125] Then, as shown in equation (6) above, the inverse matrix D is applied to the fluorescence detection signal obtained by receiving light in the light receiving unit 13. -1 By performing a multiplication operation, it is possible to calculate (separate) Red_INK, i.e., the amount of light emitted by the corrected red visible fluorescent ink, and IR_INK, i.e., the amount of light emitted by the corrected infrared fluorescent ink.

[0126] This inverse matrix D -1 This value may be stored in the memory unit as a correction value.

[0127] Similarly, when using blue or green visible fluorescent ink as a specific color, the luminescence amount of the corrected blue or green visible fluorescent ink (Blue_INK or Green_INK) can be separated from the luminescence amount of the corrected infrared fluorescent ink (IR_INK).

[0128] These correction values ​​can also be used to set reference data. In addition, regardless of whether method (A) or (B) above is used, the authenticity of the special fluorescent ink may be determined by the fluorescence emission ratio, as described in Embodiment 1.

[0129] For example, the fluorescence detection signal obtained by receiving fluorescence emitted from a genuine banknote irradiated with ultraviolet light using one of the above correction values ​​may be used to calculate the fluorescence emission amount of a specific visible color (e.g., Green_INK or Red_INK above) and the fluorescence emission amount of infrared light (e.g., IR_INK above) of a genuine banknote. Then, the fluorescence emission ratio α may be calculated using the following formula (7) and used as reference data.

[0130]

number

[0131] The following describes an example of authenticity determination using the above correction values ​​(especially equation (3)) and fluorescence emission ratio α.

[0132] As shown in Figure 7, here we assume that there are two areas (the regions enclosed by frames 51 and 52) where we want to perform authenticity determination by fluorescence measurement. Frame 51 is printed with green visible fluorescent ink, and frame 52 is printed with a special fluorescent ink that emits fluorescence in the green wavelength band and the infrared region. When ultraviolet light is irradiated onto these areas and the fluorescence is received by the light receiving unit 13, the amount of light emitted (output value) is measured, output values ​​such as those shown in Table 3 below can be obtained.

[0133] [Table 3]

[0134] CH_B represents the output value of the first photodetector 31B, CH_G represents the output value of the second photodetector 31G, and CH_R represents the output value of the third photodetector 31R.

[0135] From these measurement results and the correction formula (3) above, the amount of Green_INK, i.e., the amount of light emitted by the corrected green visible fluorescent ink, and the amount of light emitted by IR_INK, i.e., the amount of light emitted by the corrected infrared fluorescent ink, for each of frame 51 and frame 52 can be calculated, and the results shown in Table 4 below can be obtained, for example. Furthermore, from the correction formula (7) above, the fluorescence emission ratio α can be calculated for each of frame 51 and frame 52, and the results shown in Table 4 below can be obtained, for example.

[0136] [Table 4]

[0137] Here, for example, if the fluorescence emission ratio α, which is pre-calculated as standard data from genuine banknotes, is 1.6, and the tolerance range for variation due to variability (transportation, deterioration, calculation errors) is set to 50%, then α = 0.8 to 2.4 is considered true (tolerance range). In that case, as shown in Table 5 below, frame 52 can be determined to be "genuine" and frame 51 to be "fake," thus determining authenticity.

[0138] [Table 5]

[0139] Note that normalization is performed using a correction formula here, but normalization is not required in either method (A) or (B) above. In that case, the relative fluorescence emission amount to the reference specific color of visible fluorescent ink and infrared fluorescent ink can be obtained, making it easy to detect deterioration caused by banknote circulation, etc.

[0140] (Embodiment 3) In this embodiment, we will describe the case where spectral overlap correction is not performed.

[0141] As shown in Figure 8, in this embodiment, the light-receiving unit 13 includes a first light-receiving element 41B having a color filter 42B, a second light-receiving element 41G having a color filter 42G, a third light-receiving element 41R having a color filter 42R, and a fourth light-receiving element 41IR having a color filter 42IR.

[0142] The light-receiving unit 13 may include a plurality of pixels 40 arranged in a line in the main scanning direction D1 (the direction perpendicular to the transport direction of the banknote BN, the Y direction), and each pixel 40 may include one first light-receiving element (image sensor) 41B, one second light-receiving element (image sensor) 41G, one third light-receiving element (image sensor) 41R, and one fourth light-receiving element (image sensor) 41IR, and the first light-receiving element 41B, the second light-receiving element 41G, the third light-receiving element 41R, and the fourth light-receiving element 41IR may be arranged in this order in a line in the main scanning direction D1.

[0143] As shown in Figure 8, the first light-receiving element 41B may include a photodetector 43 and a color filter 42B, the second light-receiving element 41G may include a photodetector 43 and a color filter 42G, the third light-receiving element 41R may include a photodetector 43 and a color filter 42R, and the fourth light-receiving element 41IR may include a photodetector 43 and a color filter 42IR.

[0144] As shown in Figure 9, color filter 42B transmits blue light, color filter 42G transmits green light, and color filter 42R transmits red light, but color filters 42B, 42G, and 42R do not transmit infrared light. Therefore, the first light-receiving element 41B, the second light-receiving element 41G, and the third light-receiving element 41R each receive only their corresponding visible light and do not receive infrared light. Color filter 42B absorbs green light, red light, and infrared light, color filter 42G absorbs blue light, red light, and infrared light, and color filter 42R absorbs blue light, green light, and infrared light. Color filter 42IR transmits infrared light but absorbs visible light without transmitting it.

[0145] Therefore, the light-receiving unit 13 separates the visible-range fluorescent component and the infrared-range fluorescent component emitted from the special fluorescent ink, receives them independently, and outputs signal values ​​corresponding to the light intensity of each component, thus eliminating the need for spectral overlap correction.

[0146] In this embodiment as well, the authenticity of the special fluorescent ink may be determined by the fluorescence emission ratio, as described in Embodiment 1.

[0147] In this case, for example, the fluorescence emission amount of a genuine banknote irradiated with ultraviolet light is received by the light-receiving unit 13, and from the fluorescence detection signal obtained, the fluorescence emission amount of a specific visible color of the genuine banknote (for example, the output value of the first light-receiving element 41B, the second light-receiving element 41G, or the third light-receiving element 41R) and the fluorescence emission amount of infrared light (for example, the output value of the fourth light-receiving element 41IR) can be obtained, and the fluorescence emission ratio can be calculated and used as reference data.

[0148] (Embodiment 4) The paper sheet processing device according to this embodiment may have, for example, the configuration shown in Figure 10. The paper sheet processing device 300 shown in Figure 10 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 10) 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.

[0149] 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 11. As shown in Figure 11, 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.

[0150] As shown in Figure 11, the upper unit 110 is equipped with two reflective light sources 111, a condensing lens 112, and a light receiving unit 113. The reflective light sources 111 sequentially irradiate the main surface (hereinafter referred to as surface A) of the banknote BN on the light receiving unit 113 side with illumination light having different wavelength bands, specifically infrared light, 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.

[0151] The lower unit 120 includes two reflective light sources 121 and one transmissive light source 124, a condensing lens 122, and a light receiving unit 123. The reflective light sources 121 irradiate the main surface (hereinafter referred to as the B-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.

[0152] 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.

[0153] 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.

[0154] 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 11 (main scanning direction D1), and a plurality of LED elements (not shown) provided at both ends (or one end) of the light guide.

[0155] 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.

[0156] 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.

[0157] As shown in Figure 5, each light-receiving unit 113, 123 is equipped with a plurality of pixels 30 arranged in a row in the main scanning direction D1 (the direction perpendicular to the transport direction of the banknote BN, the Y direction). Each pixel 30 is equipped with one first light-receiving element (image sensor) 31B, one second light-receiving element (image sensor) 31G, and one third light-receiving element (image sensor) 31R. The first light-receiving element 31B, the second light-receiving element 31G, and the third light-receiving element 31R are arranged in this order in a row in the main scanning direction D1.

[0158] The upper unit 110 and the lower unit 120 each repeatedly capture images of the banknote BN being transported in the transport direction and output signals corresponding to the amount of light received, thereby enabling the imaging unit 211 to acquire an image of the entire banknote BN. Specifically, the imaging unit 211 acquires a transmitted image and a reflected image of side A of the banknote BN based on the output signal of the upper unit 110, and acquires a reflected image of side B of the banknote BN based on the output signal of the lower unit 120.

[0159] 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.

[0160] Next, the configuration of the paper sheet identification device according to this embodiment will be described using Figure 12. As shown in Figure 12, the paper sheet identification device 200 according to this embodiment includes a detection unit 210, a control unit 220, and a storage unit 230.

[0161] 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.

[0162] 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.

[0163] The memory unit 230 is composed of a non-volatile storage device such as a semiconductor memory or a hard disk, and stores various programs and data for 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.

[0164] 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.

[0165] 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.

[0166] 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.

[0167] 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 data for one row in the horizontal direction (the direction perpendicular to the banknote transport direction, the Y direction) of the acquired image.

[0168] 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.

[0169] The identification unit 223 performs spectral overlap correction on the fluorescence detection signal acquired by the imaging unit 211. For example, based on the correction formula represented by the above formula (3) or (6), by correcting the fluorescence detection signal corresponding to the identification target location of the fluorescence image, the fluorescence emission amount of the visible specific color and the fluorescence emission amount of infrared light of the banknote to be identified are calculated. This identification target location may be set according to the denomination of the banknote.

[0170] Then, the identification unit 223 determines whether the authenticity of the banknote BN to be identified is within the allowable range based on whether the calculated fluorescence emission amount of visible light and the fluorescence emission amount of infrared light of the banknote BN to be identified are within the reference data regarding the fluorescence emission amount of visible light and the fluorescence emission amount of infrared light in a genuine banknote.

[0171] (Modification Example 1) In the above embodiment, the inverse matrix B -1 or D -1 may be stored as a correction value, or the matrix B or D may be stored as a correction value. In this case, after calculating the inverse matrix B -1 or D -1 of the matrix B or D stored in the storage unit, the inverse matrix B -1 or D -1 can be multiplied by the fluorescence detection signal collected from the banknote to be identified. ​​​​​​​​​​​​​​​​​​Furthermore, in the above embodiment, instead of a matrix, an expanded formula of an operation using the matrix may be stored as the correction value. Specifically, the expanded formula of formula (3) or (6) may be stored. In this case, the fluorescence detection signal taken from the banknote to be identified can be substituted into the expanded formula.

[0174] (Modification 4) In the above embodiment, reference visible fluorescent ink and infrared fluorescent ink of a specific color are measured in advance and correction values ​​are calculated. However, the visible fluorescent ink and infrared fluorescent ink may be incorporated into the device itself. For example, reference visible fluorescent ink and infrared fluorescent ink of a specific color may be printed at predetermined locations within the paper sheet identification device, for example, in an area outside the transport path of the banknotes to be identified. The fluorescence emitted from the printed pattern of the visible fluorescent ink, the fluorescence emitted from the printed pattern of the infrared fluorescent ink, and the fluorescence emitted from the banknotes to be identified may be simultaneously received by different light-receiving elements (or pixels) in the light-receiving unit. During the identification process of the banknotes to be identified, the fluorescence emitted from the printed pattern of the visible fluorescent ink and the fluorescence emitted from the printed pattern of the infrared fluorescent ink may be received and used to calculate and use correction values.

[0175] (Variation 5) 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.

[0176] 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]

[0177] As described above, this disclosure is a useful technology for identifying highly secure paper sheets using photoluminescent compounds. [Explanation of Symbols]

[0178] 1,200: Paper sheet identification device 11, 111, 121, 124: Light source 13, 113, 123: Light receiving section 23, 223: Identification section 30, 40: pixels 31B, 31G, 31R, 41B, 41G, 41R, 41IR: Photodetector 32B, 32G, 32R, 42B, 42G, 42R, 42IR: Color filters 33, 43: Photodetector 110: Upper unit 112, 122: Focusing lens 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: Banknote Processing Device 301: Hoppa 302: Rejection Department 303:Operation unit 304: Enclosure 305: Display section 306a~306d: Accumulation section BN:Banknote

Claims

1. A light source capable of irradiating the paper sheets to be identified with at least ultraviolet light, A light receiving unit that receives photoluminescence emitted from the paper sheets to be identified, which have been irradiated with ultraviolet light, and outputs a photoluminescence detection signal, An identification unit identifies the paper sheets to be identified based on whether the amount of visible light photoluminescence emission and infrared light photoluminescence emission of the paper sheets to be identified are within an acceptable range compared to reference data regarding the amount of visible light photoluminescence emission and infrared light photoluminescence emission of genuine paper sheets, using the photoluminescence detection signal output from the light receiving unit. A paper sheet identification device characterized by being equipped with the following features.

2. 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 1, characterized in that it is a paper sheet identification device.

3. 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 amount of photoluminescence emission of at least one color 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 1 or 2, characterized in that it is a paper sheet identification device.

4. 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 3, characterized in that it is a paper sheet identification device.

5. 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 3, characterized in that it is a paper sheet identification device.

6. 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 3, characterized in that it is a paper sheet identification device.

7. 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 the features 1 to 6.

8. 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, and a third light-receiving element having a color filter that transmits red light and infrared light. A paper sheet identification device according to any one of the features 1 to 7.

9. The identification unit uses a correction value based on a photoluminescence detection signal obtained by receiving the photoluminescence emitted from the paper sheets to be identified, which have been irradiated with ultraviolet light, using a correction value based on the photoluminescence detection signal obtained by receiving the photoluminescence emitted from the paper sheets to be identified, which have been irradiated with ultraviolet light, using a correction value based on the photoluminescence detection signal obtained by receiving the photoluminescence emitted from the paper sheets to be identified, which have been irradiated with ultraviolet light, to calculate the amount of photoluminescence emitted from the paper sheets to be identified, which have been irradiated with infrared light, and to identify the paper sheets to be identified based on whether the amount of photoluminescence emitted from the paper sheets to be identified, which have been irradiated with infrared light, are within an acceptable range with respect to the reference data. The paper sheet identification device according to claim 8, characterized in that it is a paper sheet identification device.

10. The correction value is based on the output values ​​of two photodetectors selected from the first photodetector, the second photodetector, and the third photodetector. The paper sheet identification device according to claim 9, characterized in that it is a paper sheet identification device.

11. One of the two light-receiving elements is a light-receiving element that outputs a maximum value when it receives photoluminescence emitted by the visible photoluminescence ink, among the first light-receiving element, the second light-receiving element, and the third light-receiving element. The other of the two light-receiving elements is a light-receiving element among the first, second, and third light-receiving elements that outputs a maximum value when it receives photoluminescence emitted by the infrared photoluminescence ink. The paper sheet identification device according to claim 10, characterized in that it is a paper sheet identification device.

12. The correction value is based on a 2x2 matrix composed of output values ​​obtained by receiving the photoluminescence emitted by the visible photoluminescence ink and the photoluminescence emitted by the infrared photoluminescence ink individually with the two photodetectors. The paper sheet identification device according to claim 11, characterized in that it is a paper sheet identification device.

13. The aforementioned correction value is based on the matrix obtained by normalizing the aforementioned matrix. The paper sheet identification device according to claim 12, characterized in that it is a paper sheet identification device.

14. The aforementioned correction value is based on the inverse matrix of the aforementioned matrix. The paper sheet identification device according to claim 12 or 13, characterized in that it is a paper sheet identification device.

15. If the light-receiving element that outputs a maximum value when it receives photoluminescence emitted by the visible photoluminescence ink and the light-receiving element that outputs a maximum value when it receives photoluminescence emitted by the infrared photoluminescence ink are the same, then that light-receiving element will be denoted as light-receiving element P. The output values ​​of the first light-receiving element, the second light-receiving element, and the third light-receiving element when the photoluminescence emitted by the visible photoluminescence ink is received by the light-receiving unit are denoted as a, b, and c, respectively. When the photoluminescence emitted by the infrared photoluminescence ink is received by the light-receiving unit, the output values ​​of the first light-receiving element, the second light-receiving element, and the third light-receiving element are denoted as d, e, and f, respectively. The correction value is based on the output value of the photodetector P and the combination of the sum of the output values ​​a to f that shows the largest difference among (d+e)-(a+b), (e+f)-(b+c), (d+f)-(a+c), and (d+e+f)-(a+b+c). The paper sheet identification device according to claim 9, characterized in that it is a paper sheet identification device.

16. The correction value is based on a 2x2 matrix consisting of the output values ​​obtained by individually receiving the photoluminescence emitted by the visible photoluminescence ink and the photoluminescence emitted by the infrared photoluminescence ink with the light-receiving element P, and the sum of the values ​​showing the largest difference. The paper sheet identification device according to claim 15, characterized in that it is a paper sheet identification device.

17. The aforementioned correction value is based on the matrix obtained by normalizing the aforementioned matrix. The paper sheet identification device according to claim 16, characterized in that it is a paper sheet identification device.

18. The aforementioned correction value is based on the inverse matrix of the aforementioned matrix. The paper sheet identification device according to claim 16 or 17, characterized in that it is a paper sheet identification device.

19. The light-receiving unit comprises a first light-receiving element having a color filter that transmits blue light, a second light-receiving element having a color filter that transmits green light, a third light-receiving element having a color filter that transmits red light, and a fourth light-receiving element having a color filter that transmits infrared light. A paper sheet identification device according to any one of the features 1 to 7.

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 at least ultraviolet light from a light source, The steps include: receiving photoluminescence emitted from the paper sheets to be identified, which have been irradiated with ultraviolet light, with a light-receiving unit and outputting a photoluminescence detection signal; The steps include: using the photoluminescence detection signal output from the light receiving unit to identify the paper sheets to be identified, and determining 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 with respect to reference data regarding the visible light photoluminescence emission amount and infrared light photoluminescence emission amount of genuine paper sheets; A method for identifying paper sheets, characterized by comprising the following features.

22. The process involves irradiating the paper sheets to be identified with at least ultraviolet light from a light source, The process involves receiving photoluminescence emitted from the paper sheets to be identified, which have been irradiated with ultraviolet light, with a light-receiving unit and outputting a photoluminescence detection signal. The process involves using the photoluminescence detection signal output from the light receiving unit to identify the paper sheets to be identified, and determining 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 relative to reference data regarding the visible light photoluminescence emission amount and infrared light photoluminescence emission amount of genuine paper sheets. A paper sheet identification program characterized by causing a paper sheet identification device to execute the following.

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