RU2530276C2 - Authentication device, method of authentication and fluorescence sensor - Google Patents

Abstract

FIELD: printing.

SUBSTANCE: group of inventions relates to means of authentication of documents. In the method, the irradiation with the excitation light is carried out, the first module of light receiving receives light having a first wavelength range, that comprises the peak wavelength of fluorescence, excited in the fluorescent substance, as a result of irradiation by the excitation light, and the second module of light receiving receives light emitted from the same area as the area of the sheet of paper, which emits light received by the first module of receiving light, the said light has the second wavelength range, which is located next to the first wavelength range. Then the module of determining the fluorescent substance determines type of the fluorescent substance added to the sheet of paper based on the outputs from the first module of receiving light and the second module of receiving light, and the assessment module assesses whether the sheet of paper is genuine or counterfeit, based on the result of assessment of the module of determining the fluorescent substance.

EFFECT: technical result is to improve the detection accuracy of authenticity.

13 cl, 21 dwg

Description

FIELD OF THE INVENTION

The present invention relates to an authentication device, an authentication method, and a fluorescence sensor, which are used to determine the authenticity of sheets of paper containing a fluorescent substance. The present invention, in particular, relates to an authentication device, an authentication method and a fluorescence sensor, which allows to differentiate and detect fluorescent substances which, when excited as a result of irradiation with an excitation light, emit fluorescent light having peak wavelengths that are adjacent to each other .

State of the art

Authentication devices that use a transport mechanism to transport sheets of paper, such as gift vouchers, and an optical sensor that transmits and receives visible light, infrared light, etc., to determine the authenticity of transported sheets of paper, are known in the art.

Recently, to prevent counterfeiting, signs or patterns have been printed on sheets of paper using ink containing a fluorescent substance that cannot be checked with the naked eye. When irradiated with a given excitation light (e.g., ultraviolet light), ink containing a fluorescent substance emits fluorescent light having a peak wavelength, which depends on the type of fluorescent substance contained in the ink.

This has led to the introduction of authentication devices that use such characteristics of ink containing a fluorescent substance. In particular, a sheet of paper already labeled as a latent image using counterfeit ink, such as ink containing a fluorescent substance printed on it, is irradiated with excitation light having a predetermined wavelength, and latent image marks are detected using the device authentication using photodetection of fluorescent light emitted from ink containing a fluorescent substance. The authenticity of a sheet of paper is determined based on whether latent image marks have been detected.

For example, Patent Document 1 discloses a technology in which a bar code is read out to determine the authenticity of the printed material, which is not visually visible, and which is formed using inks printed on printed material designed to combat counterfeiting, containing a fluorescent substance, peak length whose waves range from 800 nanometers (nm) to 900 nm.

In particular, in the technology disclosed in Patent Document 1, the barcode is irradiated with excitation light, and the barcode is read by detecting the fluorescent light emitted by the barcode using a detector that detects light in a predetermined wavelength band that includes peak wavelength (800 nm - 900 nm) of a fluorescent substance.

[Background Documents]

[Patent Documents]

[Patent Document 1] Japanese Patent Application Laid-Open No. 2007-136838

SUMMARY OF THE INVENTION

 The tasks solved by the invention

However, the technology disclosed in Patent Document 1 cannot be used to differentiate and detect fluorescent substances having peak wavelengths that are adjacent to each other. The reason for this is that the technology disclosed in Patent Document 1 can only be used to determine whether a particular fluorescent substance is applied to a sheet of paper by detecting light emitted by fluorescent substances whose peak wavelength is within the detection range of the detector.

Therefore, if a plurality of fluorescent substances are deposited on a sheet of paper, and if the peak wavelengths of light emitted from these fluorescent substances are adjacent to each other, the technology disclosed in Patent Document 1 cannot be used to identify a fluorescent substance among a plurality of fluorescent substances detected detector.

Since there are also cases when a lot of fluorescent substances are deposited on one sheet of paper as an additional measure to combat counterfeiting, the problem arises of how to differentiate fluorescent substances that emit light whose peak wavelengths are next to each other.

The present invention was developed to solve the problem associated with conventional technology, and the purpose of the present invention is to provide an authentication device, authentication method and a fluorescence sensor that allows to differentiate and detect fluorescent substances that, when excited by irradiation with excitation light, emit fluorescent light, having peak wavelengths adjacent to each other.

Means for solving the problem

To solve the above problem and to achieve the above goals, in accordance with an aspect of the present invention, an authentication device that authenticates a sheet of paper with a fluorescent substance deposited thereon includes an irradiation module that irradiates a sheet of paper with excitation light; a first photo detector that performs light detection of a first wavelength band that includes a peak wavelength of fluorescent light excited from a fluorescent substance when irradiated with excitation light; a second photodetector that detects light emitted from the same area on the sheet of paper from which the light detected by the first photodetector emits, and which is located in a second wavelength band that is adjacent to the first wavelength band; an identification module that identifies, based on the output of the first photodetector and the output of the second photodetector, the type of fluorescent substance deposited on a sheet of paper; and an authenticity determination module that determines the authenticity of the paper sheet based on the identification result obtained by the identification module.

In the above aspect, the first photodetector and the second photodetector are located in the same plane, so that photodetection of fluorescent light excited from the same area on a sheet of paper is performed.

In the above aspect, the identification module identifies the type of fluorescent substance deposited on a sheet of paper if the comparison value obtained from the output of the first photodetector and the output of the second photodetector is greater than or equal to a predetermined threshold value.

In the above aspect, the identification module identifies the fluorescent substance deposited on a sheet of paper as the first fluorescent substance if the comparison value obtained from the output of the first photodetector and the output of the second photodetector is less than a predetermined threshold value and as a second fluorescent substance emitting a spectrum in narrower band than the first fluorescent substance, if the comparison value is greater than or equal to a predetermined threshold value.

The authentication device further includes a third photodetector that photodetects the light that is emitted from the same area on the paper sheet from which the light detected by the first photodetector is emitted and which is in the third wavelength band, which includes the first wavelength band and a second wavelength band. The identification module identifies the type of fluorescent substance after correcting the output of the first photodetector and the output of the second photodetector, based on the output of the third photodetector.

In the above aspect, the identification module identifies the type of fluorescent substance after correcting the output of the first photodetector and the output of the second photodetector based on the comparison result obtained from the output of the third photodetector and a preset reference value.

In the above aspect, the identification module identifies the fluorescent substance deposited on a sheet of paper as the first fluorescent substance if the comparison value obtained from the output of the third photodetector based on light from the area where the fluorescent substance is applied and the output of the third photodetector based on light from the area where the fluorescent substance is not applied, greater than or equal to a predetermined threshold value, and as a second fluorescent substance having a spectrum with a narrower band than the first fluorescent solid substance, if the comparison value is less than the specified threshold value.

In the above aspect, the identification module identifies the type of fluorescent substance deposited on the paper sheet based on the first evaluation value, which is the comparison value obtained from the output of the first photodetector and the output of the second photodetector, and the second evaluation value, which is the comparison value obtained from the exit of the third photodetector based on light from the area where the fluorescent substance is applied, and from the third photodetector based on light from the area where the fluorescent The substance is not applied.

In accordance with yet another aspect of the present invention, a method for determining the authenticity of a sheet of paper having a fluorescent substance deposited thereon includes: irradiating the sheet of paper with excitation light; photodetection of light emitted from the same region on a sheet of paper is performed by irradiation with excitation light, light in the first wavelength band, which includes a peak wavelength of fluorescent light excited by the excitation light, using the first photodetector, and light in the second a wavelength band that is adjacent to the first wavelength band using a second photodetector; identify the type of fluorescent substance deposited on a sheet of paper based on the output of the first photodetector and the output of the second photodetector; and determining the authenticity of the sheet of paper based on the identification result obtained by identification.

In accordance with yet another aspect of the present invention, a fluorescence sensor that detects a fluorescent substance deposited on a sheet of paper includes an irradiation module that irradiates the sheet of paper with excitation light; a first photodetector that performs photodetection of light in a first wavelength band that includes a peak wavelength of fluorescent light excited from a fluorescent substance by irradiation with excitation light; and a second photodetector that photodetects the light emitted from the same area on the paper sheet from which the light detected by the first photodetector is emitted, and which is located in a second wavelength band that is adjacent to the first wavelength band.

In the above aspect, the first photodetector includes a first photodetection element and a first filter that allows only light in the first wavelength band, which includes the peak wavelength of the fluorescent light excited by the fluorescent substance, to be among the light emitted from the paper sheet, the second photodetector includes a second photodetection element and a second filter that transmits from the light coming from a sheet of paper, only light in the second wavelength band, which is located next to the first nth wavelength band, and the first photodetection element and the second photodetection element are located in the same plane so that they perform photodetection of fluorescent light excited from the same area on a sheet of paper by irradiation with excitation light.

The fluorescent sensor further includes a third photodetector that photodetects light that is emitted from the same area on the paper sheet from which the light detected by the first photodetector emits and which is in the third wavelength band, which includes the first wavelength band and a second wavelength band.

The fluorescent sensor includes a frame made of electrically conductive material, and which is installed in the module of the inner part, which includes a first photodetector, a second photodetector, a third photodetector and an irradiation module.

Preferred Effects of the Invention

In accordance with an aspect of the present invention, the irradiation module emits excitation light onto a sheet of paper, the first photodetector performs photodetection in the first wavelength band, which includes the peak wavelength of the fluorescent light excited from the fluorescent substance when irradiated with the excitation light, the second photodetector performs photodetection of light which is emitted from the same area on the sheet of paper from which the light detected by the first photodetector emits, and which is in the second band The wave line, which is located next to the first wavelength band, the identification module identifies, based on the output of the first photodetector and the output of the second photodetector, the type of fluorescent substance deposited on the paper sheet and the authenticity determination module determines the authenticity of the paper sheet based on the identification result obtained in identification module. Therefore, fluorescent substances that, when excited by irradiation with an excitation light, emit fluorescent light having peak wavelengths that are adjacent to each other, can be differentiated and detected.

In accordance with another aspect of the present invention, the first photodetector and the second photodetector are located in the same plane so as to perform photodetection of fluorescent light generated from the same area on a sheet of paper. Therefore, the detection of fluorescent light from the same area on a sheet of paper by the first photodetector and the second photodetector can be performed using a simple structure.

In accordance with another aspect of the present invention, the identification module identifies the type of fluorescent substance deposited on a sheet of paper if the comparison value obtained from the output of the first photodetector and the output of the second photodetector is greater than or equal to a predetermined threshold value. Therefore, among fluorescent substances having peak wavelengths that are adjacent to each other, a fluorescent substance having a narrow band can be differentiated and detected.

In accordance with another aspect of the present invention, the identification module identifies a fluorescent substance deposited on a sheet of paper as the first fluorescent substance if the comparison value obtained from the output of the first photodetector with the output of the second photodetector is less than a predetermined threshold value and as a second fluorescent a substance emitting a narrower bandwidth spectrum than that of the first fluorescent substance, if the comparison value is greater than or equal to a predetermined threshold value. Therefore, even if fluorescent substances having peak wavelengths that are adjacent to each other are applied to a sheet of paper, these fluorescent substances can be differentiated and detected.

In accordance with another aspect of the present invention, a third photodetector is further included that photodetects light that is emitted from the same area on a sheet of paper from which light intended to be detected by the first photodetector and which is in a third wavelength band that includes the first wavelength band and the second wavelength band, and the identification module identifies the type of fluorescent substance after correcting the output of the first photodetector and the output of the second phot detector based on the output of the third photodetector. Therefore, fluorescent substances having peak wavelengths that are adjacent to each other can be differentiated with greater accuracy.

In accordance with another aspect of the present invention, the identification module identifies the type of fluorescent substance after correcting the output of the first photodetector and the output of the second photodetector based on the comparison result obtained from the output of the third photodetector and a previously set reference value. Therefore, fluorescent substances having peak wavelengths that are adjacent to each other can be differentiated with greater accuracy.

In accordance with yet another aspect of the present invention, an identification module identifies a fluorescent substance deposited on a sheet of paper as a first fluorescent substance if the comparison value obtained from the output of the third photodetector based on the light from the region where the fluorescent substance is applied and the exit a third photodetector based on light from an area where a fluorescent substance is not applied, is greater than or equal to a predetermined threshold value, and as a second fluorescent substance having a greater a narrower passband than that of the first fluorescent substance, if the comparison value is less than a predetermined threshold value. Therefore, even if two types of fluorescent substances having peak wavelengths that are adjacent to each other are deposited on a sheet of paper, fluorescent substances can be differentiated and detected.

In accordance with yet another aspect of the present invention, the identification module identifies the type of fluorescent substance deposited on a sheet of paper based on the first evaluation value, which is the comparison value obtained from the output of the first photodetector and the output of the second photodetector, and the second evaluation value, which represents the comparison value obtained from the output of the third photodetector based on light from the region where the fluorescent substance is deposited, and the output of the third photodetector based on Ove of light from the area where the fluorescent substance is not applied. Therefore, fluorescent substances having peak wavelengths that are adjacent to each other can be differentiated with greater accuracy.

Brief Description of the Drawings

On figa and 1B shows a series of drawings, in General, representing the authentication procedure in accordance with the present invention.

Figure 2 shows a block diagram of an authentication device in accordance with an embodiment of the present invention.

3A and 3B show a series of drawings representing spectral characteristics of narrow-band inks and broad-band inks.

4A and 4B show a series of drawings representing the structure of a fluorescence sensor.

Figure 5 shows a drawing representing the structure of the photodetector circuit of the fluorescence sensor.

6A to 6D show a series of drawings representing the output of a four-segment photodiode.

7A to 7C show a series of drawings of an example of an operation performed by a fluorescent substance identification module.

On Fig shows a drawing of the General structure of the authentication device.

On figa and 9B shows a series of drawings representing the structure of the recognition module and counting.

10 is a flowchart of a process for identifying a fluorescent substance in accordance with the present embodiment.

11 is a flowchart of another process procedure performed by an authentication device in accordance with the present embodiment.

12A and 12B show a series of drawings representing the structure of a fluorescence sensor frame module.

On Fig shows a drawing of the structure of the module of the inner part of the fluorescence sensor.

14 is a drawing showing how an interior module is placed inside a frame module.

DETAILED DESCRIPTION OF THE INVENTION

Exemplary embodiments of an authentication device, an authentication method, and a fluorescent sensor in accordance with the present invention are explained in detail below with reference to the attached drawings.

Before a detailed explanation of the present embodiment, first, an overview of the authentication procedure in accordance with the present invention is explained with reference to FIGS. 1A and 1B. On figa and 1B presents a set of drawings, representing an overview of the authentication procedure in accordance with the present invention. FIG. 1A shows a general view of a fluorescent sensor, and FIG. 1B shows a method for detecting narrowband inks and broadband inks used in an authentication procedure in accordance with the present invention.

The term "narrow-band ink" refers to inks containing a fluorescent substance, which contain a fluorescent substance that forms a narrow-band fluorescence spectrum when irradiated with ultraviolet light. In contrast, the term "broadband ink" refers to inks containing a fluorescent substance, which contain a fluorescent substance that forms a broadband fluorescence spectrum when irradiated with ultraviolet light.

As shown in FIG. 1A, there are cases where, in order to prevent counterfeiting, ink containing a fluorescent substance that cannot be identified with the naked eye is applied to sheets of paper, such as gift vouchers. Such inks containing a fluorescent substance, when irradiated with a predetermined excitation light (e.g., ultraviolet light), emit fluorescent light having a peak wavelength that depends on the fluorescent substance present in the ink. Typically, ink containing a fluorescent substance deposited on a sheet of paper is detected by detecting light having a peak wavelength.

However, in recent years there have been cases where broadband ink and narrowband ink, which are inks containing a fluorescent substance, having peak wavelengths that are not adjacent to each other, are applied to sheets of paper. In this case, conventional technology cannot be used to differentiate and detect broadband inks and narrowband inks, respectively.

It is known that the transmission band of fluorescent light emitted from narrow-band ink is narrow compared to the transmission band of fluorescent light emitted from wide-band ink. Accordingly, during the authentication procedure in accordance with the present invention, broadband inks and narrow-band inks are distinguished and detected by detecting differences in bandwidths (i.e., in the degree of peak slope).

In the authentication procedure in accordance with the present invention, as shown in FIG. 1A, light emitted from the same area on a paper sheet when irradiated with excitation light can be detected by a first photo detector through a first filter and a second photo detector through a second filter.

In particular, the first filter is a band-pass filter that allows light having a first wavelength to pass through it, which is the peak wavelength of broadband ink and narrowband ink (see (A-1) of FIG. 1A); the second filter is a band-pass filter that transmits light having a second wavelength that is adjacent to the first wavelength (see (A-2) in FIG. 1A).

Thus, in the authentication procedure in accordance with the present invention, the first photodetector performs photodetection of light having a first wavelength that includes a peak wavelength of broadband ink and narrowband ink, and the second photodetector performs photodetection of light having a second wavelength, which located next to the first wavelength.

Fluorescent light emitted from a fluorescent substance is known to be scattered in a relatively wide area in nature. In the authentication procedure, in accordance with the present invention, this property of fluorescent light is used, and when placing the first photodetector and the second photodetector within the irradiation section of the fluorescent light coming from the same area on the paper sheet, it becomes possible to detect fluorescence light from one and the same area on a sheet of paper by each photo detector using a simple structure.

In the authentication procedure in accordance with the present invention, the types of fluorescent substances deposited on a sheet of paper can be identified based on the output of the first photodetector and the output of the second photodetector.

In particular, as shown in FIG. 1B, a strip of fluorescent light emitted from narrowband ink is narrower than a strip of fluorescent light emitted from broadband ink. Therefore, the difference between the spectral intensity of the peak wavelength and the spectral intensity of the wavelength near the peak may be greater for narrowband inks compared to broadband inks. Thus, when narrowband ink is irradiated with excitation light, a comparison value (for example, a difference value) obtained from the output of the first photodetector and the output of the second photodetector may be larger than that of wideband ink.

Thus, if the comparison value obtained from the output of the first photodetector and the output of the second photodetector is greater than or equal to a predetermined threshold value, ink containing fluorescent substance deposited on a sheet of paper is identified as narrow-band ink, and if the comparison value is less than the threshold meaning, an ink containing a fluorescent substance is identified as broadband ink. In the authentication procedure in accordance with the present invention, the authenticity of a sheet of paper is determined based on the identification result of the ink containing the fluorescent substance.

Thus, in the authentication procedure in accordance with the present invention, among the light output from the same area on a sheet of paper, the first photodetector detects light belonging to the first wavelength band, which includes the peak wavelength of the fluorescent light excited from a fluorescent substance by irradiating the excitation light, and a second photodetector detects light having a second wavelength band that is adjacent to the first wavelength band.

In addition, in the authentication method in accordance with the present invention, the type of fluorescent substance deposited on a sheet of paper can be identified based on the output of the first photodetector and the output of the second photodetector. Accordingly, fluorescent substances that, when excited by irradiation with excitation light, emit fluorescent light having peak wavelengths that are adjacent to each other, can be differentiated and detected.

In this case, the position of the second wavelength is simply determined as being adjacent to the first wavelength; however, it can be more specifically established based on the spectral waveforms of narrow-band ink and broad-band ink. For example, in the authentication procedure in accordance with the present invention, the wavelength for which the comparison value obtained from the output of the first photodetector and the output of the second photodetector is the largest between narrowband ink and broadband ink, can be set as the second wavelength. As a result of this, narrow-band ink and broad-band ink can be differentiated with greater accuracy.

In the authentication procedure in accordance with the present invention, a third photodetector is provided that detects light in a wavelength band that includes a first wavelength and a second wavelength. The output of the third photodetector is additionally used in the authentication procedure in accordance with the present invention to improve the accuracy with which ink containing a fluorescent substance is identified.

An embodiment of an authentication device, an authentication method, and a fluorescence sensor, in which an authentication procedure is explained with reference to FIGS. 1A and 1B, is described in detail below. The following is a case in which two types of ink, namely, broadband ink and narrowband ink, were deposited on a sheet of paper, which is the purpose of authentication. A sheet of paper may be a gift coupon, security, bond, check, banknote, etc.

[Embodiment]

The structure of the authentication device 1 is explained first with reference to FIG. Figure 2 shows a block diagram of an authentication device 1. As shown in FIG. 2, the authentication device 1 includes a fluorescence sensor 11, other sensors 12, a storage unit 13, and a control unit 14. The control module 14 includes a fluorescent substance identification module 14a and a determination module 14b.

Only the constituent elements that are necessary to explain the basic elements of the authentication device 1 are shown in FIG. A more specific structure of the authentication device 1 is explained below with reference to FIG. 8, etc.

The fluorescence sensor 11 detects ink containing a fluorescent substance deposited on a sheet of paper by irradiating the sheet of paper with excitation light. In the present embodiment, narrow-band inks and broad-band inks have been applied as inks containing a fluorescent substance to a sheet of paper.

The spectral characteristics of narrowband inks and broadband inks are explained with reference to FIGS. 3A and 3B. FIG. 3A and 3B show a set of drawings representing spectral characteristics of narrow-band inks and broad-band inks. 3A is a drawing showing an example of a sheet of paper with narrow-band ink and broad-band ink applied thereon. FIG. 3B is a drawing set showing spectral characteristics of narrow-band inks and broad-band inks.

As shown in FIG. 3A, narrowband ink and broadband ink are applied in predetermined areas of a sheet of paper. The areas on which the narrow-band ink is applied and the areas on which the broad-band ink is applied are previously stored as templates for each type of paper in the authentication device 1.

For example, in the present embodiment, as shown in FIG. 3B, fluorescent light excited by either narrow-band ink or broad-band ink has a peak at a wavelength of 613 nm. While fluorescent light excited by narrow-band ink exhibits a narrow peak, which is a peak with a narrow (steep) passband (see (B-1) in FIG. 3B), fluorescent light excited by broadband ink exhibits a wide peak which is a peak with a wide (gradual) bandwidth (see (B-2) of FIG. 3B).

The first wavelength band and the second wavelength band shown in FIG. 3B correspond to wavelength bands of light detected by the first photodetector 115a and the second photodetector 115b, respectively, which are explained below.

The structure of the fluorescence sensor 11 is explained with reference to FIGS. 4A and 4B. FIG. 4A and 4B are a set of drawings representing the structure of a fluorescence sensor 11. FIG. 4A is a schematic cross-sectional view of a fluorescence sensor, and FIG. 4B is a drawing showing an arrangement relating to a four-segment photodiode, bandpass filters, and a UV cut-off filter.

As shown in FIG. 4A, the fluorescence sensor 11 includes a UV_LED 111, a UV filter 112, a reflecting UV filter 113 and a window 114. The fluorescence sensor 11 further includes a four-segment photodiode 115, two types of band-pass filters 116a and 116b and a UV cut-off filter 117.

UV_LED 111 is a light source that emits excitation light, which generates fluorescent light emitted by ink containing a fluorescent substance. In particular, UVJLED 111 emits ultraviolet light as an excitation light. A UV transmission filter 112 allows ultraviolet light to pass through it, but blocks visible light, and is located between the UVJLED 111 and the UV reflection filter 113.

The UV reflection filter 113 reflects ultraviolet light that is emitted by UV_LED 111 and has been passed through the UV transmission filter 112, and irradiates a sheet of paper with reflected ultraviolet light. In addition, the UV reflective filter 113 passes visible light among other light emanating from the sheet of paper due to irradiation with ultraviolet light, and allows it to be detected by a four-segment photodiode 115. A window 114 allows light to pass through and is located between the reflective UV filter 113 and the sheet paper.

Thus, the ultraviolet light emitted by UV_LED 111, after passing through the UV transmission filter 112, is reflected by the UV reflection filter 113 in the direction perpendicular to the sheet of paper, and enters the sheet of paper. The fluorescent light that is excited by irradiation with ultraviolet light and scattered by a sheet of paper, after passing through a UV reflection filter 113, enters the four-segment photodiode 115 through a band-pass filter 116a or a band-pass filter 116b, or a cut-off UV filter 117.

The four-segment photodiode 115 is a photodetection module including four photodetectors that are arranged in a 2 × 2 square shape (see FIG. 4B). For example, a segmented type S5980 photodiode manufactured by Hamamatsu Photonics can be used as a four-segment photodiode 115. A segmented photodiode can simultaneously detect light in the same wavelength bands in four places, and can be used, for example, to detect a position, align the axis of the laser light, etc. .d. All segments of such a four-segment photodetector are located in one plane, as shown in FIG.

In the present embodiment, each of the photodetectors 115a-115d can be configured to detect light from different wavelength bands due to the placement of the bandpass filter 116a or the bandpass filter 116b, or the UV cut-off filter 117 above each of the photodetectors 115a-115d of the four-segment photo diode 115.

The band-pass filters 116a and 116b transmit visible light that has a different wavelength among the visible light coming from the paper sheet into the four-segment photodiode 115 through the UV reflecting filter 113, and are located on the near and far sides, respectively, above the surface of the paper sheet.

In particular, the bandpass filter 116a allows visible light to pass through the wavelength band (first wavelength band) of 12 nm, centered at 613 nm, which is the peak wavelength of narrowband ink and broadband ink; and a band-pass filter 116b allows visible light to pass through it in a wavelength band (second wavelength band) of a width of 12 nm, with a center of 600 nm, which is close to 613 nm.

The UV cut-off filter 117 blocks ultraviolet light, and passes visible light from all bands of visible light, including a first wavelength band and a second wavelength band through it.

The four-segment photo diode 115 includes a first photodetector 115a, a second photodetector 115b, a third photodetector 115c, and a fourth photodetector 115d. The bandpass filter 116a is positioned so that it corresponds to the first photodetector 115a, and the bandpass filter 116b is located so that it corresponds to the second photodetector 115b. The UV cut-off filter 117 is arranged so that it matches both the third photodetector 115c and the fourth photodetector 115d.

Using the structure described above, visible light in each of three different wavelength bands is detected using a four-segment photodiode 115. In particular, in a four-segment photo diode 115, the first photodetector 115a detects visible light in the first wavelength band, which includes a peak wavelength ( 613 nm) of narrow-band ink and broad-band ink, the second photodetector 115b detects visible light in a second wavelength band that is adjacent to the first wavelength band, while the third photodetector 115c and fourth th photodetector 115d detect visible light in the entire band of visible light.

In the fluorescence sensor, in accordance with the present embodiment, the fact that fluorescent light excited from the fluorescent substance is scattered over a wide area and four photodetectors 115a-115d are located within the irradiation region of the fluorescent light excited from the sheet of paper is used. Thus, in the fluorescence sensor, in accordance with the present embodiment, four photodetectors 115a-115d are located in the same plane so that they are capable of detecting fluorescence that is excited from one area on a sheet of paper. Thus, fluorescent light excited from the same area on a sheet of paper can be detected by each of the photodetectors 115a-115d using a simple structure.

When using such a structure, it is not necessary to place a lens for converging fluorescent light excited from a sheet of paper, a beam splitter for projecting fluorescence collected by the lens, and the like. Therefore, a compact fluorescence sensor can be implemented, and the cost of its production can be low.

The structure of the photodetector of the fluorescence sensor 11 is explained below with reference to FIG. Figure 5 presents a drawing of the structure of the photodetector circuit of the fluorescence sensor 11.

As shown in FIG. 5, the signals output from the first photodetector 115a are amplified by an amplifier 120a, converted into digital signals by an AD (analog-to-digital) converter 122a, and stored in the storage unit 13 as data of the 613 nm band, the center of which is located at 613 nm. Below, these 613 nm bands will be called "output value A". Similarly, the signals output from the second photodetector 115b are amplified by an amplifier 120b, converted into digital signals by an AD converter 122b, and stored in a storage unit 13 as data of a 600 nm band centered at 600 nm. Below, these 600 nm bands are called "output value B".

The signals output from the third photodetector 115b and the fourth photodetector 115c are amplified by an amplifier 120c, converted into digital signals by an AD converter 122c, and stored in the storage unit 13 as common visible light band data. Below, the data of the total band of visible light is called "output value C".

As shown in FIG. 5, gain controls 121a-121c that control gain values of amplifiers 120a-120c, respectively, are located in the photodetector circuit. The fluorescence sensor 11 appropriately extracts the output AC values from the photodetectors 115a-115d, the photodetection states change due to the effect of the bandpass filters 116a and 116b and the UV cut-off filter 117 by individually adjusting the gain values of the amplifiers 120a-120c using the controls 121a-121c gain.

Below, with reference to figure 2, other constituent elements are explained. Other sensors 12 are other sensors than the fluorescence sensor 11, and are used to authenticate a sheet of paper. For example, other sensors 12 may be a tracking sensor that detects the passage of a sheet of paper, a line sensor that receives image data on a sheet of paper, a magnetic sensor that reads magnetic information from a sheet of paper, etc. The storage module 13 is a storage device that stores the output values A to C output from the fluorescence sensor 11.

The control module 14 is a processing module that identifies the type of fluorescent substance and authenticates a sheet of paper based on the identification result. The fluorescent substance identification module 14a receives the output values AC from the storage module 13, and based on the obtained output values AC, it identifies whether the ink containing the fluorescent substance deposited on the paper sheet is narrow-band ink or broad-band ink. The fluorescent substance identification module 14a performs the process of transmitting the identification result of the ink containing the fluorescent substance to the determination module 14b.

The determination module 14b is a processing module that determines the authenticity of a sheet of paper based on an identification result of ink containing a fluorescent substance obtained by the fluorescent substance identification module 14a, and outputs the results of other sensors 12.

The fluorescent substance identification process performed by the fluorescent substance identification module 14a is explained below with reference to FIGS. 6A-6D and FIGS. 7A-7C. The results output from the four-segment photodiode 115 are explained first with reference to FIGS. 6A-6D. 6A-6D show a set of drawings representing the results output by a four-segment photodiode 115.

6A-6D, the results of photo-detection of fluorescent light excited from narrow-band ink are shown on the left side, and the results of photo-detection of fluorescent light excited from wide-band ink are shown on the right side. Fig. 6A shows graphs of output values (data of the 613 nm band of Fig. 5), Fig. 6B shows graphs of output values of (data of the 600 nm band of Fig. 5), Fig. 6C shows graphs obtained after subtracting the output values B from the output values A, and FIG. 6D shows graphs of the output values C (data of the total visible light band of FIG. 5). In the graphs shown in FIGS. 6A-6D, the position of the sheet of paper is represented on the horizontal axis, and the voltage is shown on the vertical axis.

As shown in FIG. 6A, with regard to the output values A, which are the output result for the first wavelength band, the output values A have high values in the region where narrow-band ink is applied simultaneously and in the region where broadband ink is applied. This is because, as shown in FIG. 3B, fluorescent light excited by both narrow-band inks and broad-band inks has a peak in the first wavelength band.

On the other hand, as shown in FIG. 6B, with regard to the output values of B, which are the output for the second wavelength band, the output value In the narrowband ink application area is comparatively lower than the output value B in the broadband ink application area. This is due to the difference in the steepness of the shape of the spectra of narrow-band ink and broad-band ink. Thus, as shown in FIG. 3B, the spectral intensity at wavelengths near the peak of the narrow-band ink is less than that of the broad-band ink, since the band-width of the narrow-band ink is narrower than that of the broad-band ink.

Therefore, as shown in FIG. 6C, when the output values of B are subtracted from the corresponding output values of A, the obtained values for the narrow-band ink application area are larger than the values in the broadband ink application area.

The fluorescent substance identification module 14a identifies whether the fluorescent substance is narrow-band ink or broad-band ink based on the result of comparing output values A and output values B. The process of identifying a fluorescent substance performed by the fluorescent substance identification module 14a is explained below with reference to FIG. 7A- 7C.

FIGS. 7A-7C are a set of drawings representing an example of determination performed by the fluorescent substance identification module 14a. FIG. 7A is a drawing showing an example of determination for the case where the fluorescent substance is identified based on the evaluation value 1; FIG. 7B is a drawing showing an example of processing for the case where the fluorescent substance is identified based on the evaluation value 2; and FIG. 7C is a drawing showing an example of determining a case where a fluorescent substance is identified based on an overall evaluation value.

As shown in FIG. 7A, the rating value 1 is a value estimated based on the degree of steepness of the shape of the spectrum. In particular, the evaluation value 1 is obtained by subtracting the output value B from the output value A and dividing the obtained residue by the output value C (see (A-1) in FIG. 7A).

If the rating value 1 is large, that is, if the rating value 1 is greater than or equal to a predetermined threshold value, the fluorescent substance identification module 14 a identifies the fluorescent substance deposited on the paper sheet as narrow-band ink. On the other hand, if the rating value 1 is small, that is, if the rating value 1 is less than a predetermined threshold value, the fluorescent substance identification module 14a identifies the fluorescent substance deposited on a sheet of paper as broadband ink (see (A-2) for figa).

Instead of using as an estimate 1 the value obtained by simply subtracting the output value B from the output value A, the fluorescent substance identification module 14a uses the value obtained by dividing the result of the subtraction by the output value C, which is data for the entire visible light band. Thus, in the present embodiment, the fluorescent substance identification module 14a identifies the type of fluorescent substance after correcting (normalizing) the output value output from the first photodetector 115a and the output value B output from the second photodetector 115b based on the output value C of the third photodetector 115c and a fourth photodetector 115d. Therefore, comparing the estimate value 1 with a predetermined threshold value can be performed with greater accuracy, and thus, the differentiation between narrow-band ink and broadband ink can be performed with greater accuracy.

Although the case where the output value B is subtracted from the output value A has been given as an example, the present embodiment is not limited to this. An absolute value can be used for the value obtained to subtract the output value A from the output value B. Alternatively, the value obtained by dividing the output value A by the output value B or by dividing the output value B by the output value A can be used; that is, the relationship between the output value A and the output value B. can be used. Moreover, it is sufficient that the evaluation value 1 represents a comparison of the output value A and the output value B.

Although the case where the correction is performed by dividing the comparison value of the output value A and the output value B by the output value C is presented, as an example, the correction method is not limited to this. For example, the comparison value of the output value A and the output value B can be adjusted based on the result of comparing the output value C with the previously set reference value.

Thus, if the output value C is 2/3 of the reference value, the fluorescent substance identification module 14a may consider the value that is 3/2 of the residue obtained by subtracting the output value B from the output value A as the evaluation value G. This method can also be used to more accurately compare the estimated value G and the threshold value, and thus differentiation between narrow-band ink and broad-band ink can be performed with greater accuracy.

Although the case where the differentiation of narrow-band ink and broad-band ink is performed based on the evaluation value 1, which is the comparison value between the output value A and the output value B, has been explained above, the fluorescent substance identification module 14 a can use exclusively the output value C to differentiate the narrow-band ink and broadband ink. This is explained below.

As shown in FIG. 6D, for output values C, which are data of the entire visible light band, it is obvious that when comparing the difference between the value of the broadband ink application area (see (D-1) in FIG. 6D) and the value of the adjacent area where broadband ink has not been applied (see (D-2) in FIG. 6D) is greater than the difference between the value of the application area of narrow-band ink (see (D-3) in FIG. 6D) and the value of the neighboring region, where narrowband ink was not applied (see (D-4) in FIG. 6D). This is due to the difference in the spectral range of narrowband ink and broadband ink.

Thus, as shown in FIG. 3B, the spectral region of narrowband ink is smaller than the spectral region of broadband ink. Therefore, the difference between the spectral region of applying ink containing a fluorescent substance to a sheet of paper and the region of a sheet of paper where ink containing a fluorescent substance has not been applied will be greater for broadband ink. Therefore, the fluorescent substance identification module 11 a can also identify the fluorescent substance based on the output value.

In particular, as shown in FIG. 7B, the estimation value 2 obtained from the spectral region is obtained by subtracting the output value C of the neighboring region where ink is not applied from the output value C of the ink application region (see (B-1) of FIG. .7B).

If the evaluation value 2 is large, that is, if the evaluation value 2 is greater than or equal to a predetermined threshold value, the fluorescent substance identification module 14a identifies the fluorescent substance deposited on the paper sheet as broadband ink. On the other hand, if the rating value 2 is small, that is, if the rating value 2 is less than the threshold value, the fluorescent substance identification module 14a identifies the fluorescent substance deposited on the paper sheet as narrow-band ink (see (B-2) in FIG. .7B).

Thus, for the output values of C (data of the entire band of visible light in Fig. 5), if the comparison value for the value of C obtained from light in the area of application of the fluorescent substance, and the value of C obtained from light in the area where the fluorescent substance was not applied, will be greater than or equal to the predetermined threshold value, the fluorescent substance identification module 14a identifies the fluorescent substance deposited on a sheet of paper as broadband ink. If the comparison value is less than the predetermined threshold value, the fluorescent substance identification module 14 a identifies the fluorescent substance deposited on a sheet of paper as narrow-band ink. Thus, differentiation between fluorescent substances having peak wavelengths that are adjacent to each other can be performed using a single light detector.

In addition, the fluorescent substance identification module 14 a may also identify the ink containing the fluorescent substance, while taking into account the evaluation value 1 and the evaluation value 2. In particular, as shown in FIG. 7C, a comprehensive evaluation value obtained by simultaneously taking into account the evaluation value 1 and the evaluation value 2 is obtained by subtracting the value obtained by multiplying the evaluation value 2 by the weight coefficient m2 from the value obtained by multiplying values of 1 estimate for the weight coefficient m1.

Since a more reliable evaluation value 1 is used as the main evaluation value in the present embodiment, the weight coefficient m1 is set larger than for the weight coefficient m2. At the same time, m1 and m2 are both positive numbers.

Thus, narrow-band inks and broad-band inks can be differentiated with greater accuracy if the type of fluorescent substance deposited on a sheet of paper can be identified based on a rating value 1 and a rating value 2. Thus, since the assessment is carried out comprehensively, also including the assessment value 2, even in the case where the broadband ink is likely to be mistakenly identified as narrow-band ink, since the assessment value 1 is only slightly larger than the threshold value, the ink will be correctly identified. like broadband ink.

As explained above, in the present embodiment, UV_LED 111 irradiates a sheet of paper with excitation light, the first photodetector detects light in a first wavelength band that includes a peak wavelength of fluorescent light excited from the fluorescent substance as a result of irradiation with excitation light, and a second photodetector it detects light in a second wavelength band adjacent to the first wavelength band, and also light that comes from the same area of the paper sheet from which the light that should be detected by the first photodetector.

Furthermore, in the present embodiment, the fluorescent substance identification module identifies the type of fluorescent substance deposited on the paper sheet based on the exits from the first photodetector and the second photodetector, and the determination module determines the authenticity of the paper sheet based on the identification result using the fluorescent substance identification module. Thus, fluorescent substances that, when excited by irradiation with excitation light, emit fluorescent light having peak wavelengths that are adjacent to each other, can be differentiated and detected.

The general structure of the authentication device 1 is explained below with reference to FIG. On Fig shows a drawing representing the General structure of the device 1 authentication. The authentication device 1, in accordance with the present embodiment, shown in FIG. 8, not only determines the authenticity of a sheet of paper (that is, authenticates a sheet of paper), but also is used as a recognition and counting device that also performs counting of sheets of paper.

As shown in FIG. 8, the authentication device 1 includes a loader 24, where a plurality of sheets of paper P to be recognized and counted are stacked, a feed unit 26 that feeds sheets P of paper stacked in a loader 24, one at a time simultaneously into the housing 22, starting from the lowest sheet P of paper, and a transport unit 32, which conveys, one at a time, the sheet P of paper introduced into the housing 22 by the feed module 26.

A recognition and counting module 34, which includes a fluorescence sensor 11, in accordance with the present embodiment, and other sensors 12, is located in the transportation module 32. The recognition and counting module 34 is a recognition and counting device that performs recognition of a sheet P of paper supplied from the loader 24 to the inside of the housing 22 using the fluorescence sensor 11 and other sensors 12. The structure of the recognition and counting module 34 is explained below with reference to FIG. 9.

The feed module 26 includes an eject roller 26a that is adjacent to the surface of the lowest paper sheet P of a plurality of paper sheets P stacked in the loader 24, and a feed roller 26b that is located on the side after the pick roller 26a in the feed direction of the paper sheet P, and which feeds a sheet P of paper transmitted along the eject roller 26a into the inside of the housing 22. The shutter roller (backward rotating roller) 26c is located in a position opposite to the feed roller 26b, and a shutter module is formed between the feed a roller 26b and a shutter roller 26c.

The sheets P of paper supplied by the ejector roller 26a pass through the shutter roller and are transported by the conveyance unit 32 into the housing 22 one at a time at a time. As shown in FIG. 8, the transportation module 32 generates two transportation paths in place on the side after the recognition and counting module 34. One conveyance path is connected to the stacking module 36, and another conveyance path is connected to the ejection module 40.

After the sheet P of paper passes the recognition and counting module 34, it is selectively sent to the stacking module 36 or to the ejecting module 40 using the transport module 32. An opening is provided on the front side of the stacking module 36 (the right side surface in FIG. 8), through which the operator can remove the sheets P of paper laid therein. Similarly, an opening is provided on the front side of the ejection module 40, through which the operator can remove the sheets P 'of paper laid therein.

As shown in FIG. 8, the deflecting module 41, which includes the deflecting element not shown and its drive module not shown, is located at a place where the transport module 32 is divided into two transportation paths. The deflecting module 41 selectively sends a sheet of paper P, which enters the deflecting module 41 from the front side, along one of two separable transportation paths.

In the laying module 36, the laying mechanism 38 of the laying wheel type is located on the rear side of the housing 22 (to the left of the laying module 36 in FIG. 8). A stacking wheel type stacking mechanism 38 includes a stacking wheel 38a and a drive module not shown. The stacking wheel 38a rotates in a clockwise direction of FIG. 8 (in the direction of the arrow shown in FIG. 8) around an axis that is orthogonal to the surface of the sheet in FIG. 8 and that extends substantially in the horizontal direction. The stacking wheel 38a includes a plurality of vanes 38b that extend outward from the outer peripheral surface of the stacking wheel 38a in a direction opposite (counterclockwise in FIG. 8) to the rotation direction. The blades are located on the outer peripheral surface of the laying wheel 38a at regular intervals, as shown in FIG.

When the authentication device 1 is operating, the stacking wheel 38a of the stacking wheel type mechanism 38 is always driven clockwise in FIG. 8 by the drive module, and a sheet of paper P is sent to the stacking wheel 38a, one at a time, from the transport unit 32. The stacking wheel 38a receives the sheet P of paper that was transferred from the transport unit 32 between the two blades 38b and feeds the sheet P of paper trapped between the blades 38b to the stacking module 36. Thus, the sheet P of paper is fed, one at a time, from the stacking wheels 38a into the stacking module 36, and a plurality of sheets P of paper are stacked in the stack of the stacking module 36.

In the authentication device 1, a valve 50 is provided that closes the opening on the front side of the stacking module 36. The opening on the front side of the stacking module 36 is selectively closed by a valve 50. The valve 50 is moved using a valve actuator module not shown, which drives the valve 50 between the open position in which the valve 50 is in the retracted state from the hole on the front side of the laying module 36, leaving the hole in the open state, and the closed position in which Ohm, the valve 50 closes the hole on the front side of the stacking module 36. Thus, when the valve 50 is in the open position, the valve 50 is in the retracted state from the hole on the front side of the laying module 36, and the hole is open, allowing the operator access to the sheets P paper stacked in stacking module 36.

When the valve is in the closed position, the opening on the front side of the stacking module 36 is closed by the valve 50, and the operator cannot access the paper sheets P stacked in the stacking module 36. In Fig. 8, the valve 50 is shown by a solid line in the open position and the dashed line in the closed position.

In addition, as shown in FIG. 8, various types of sensors are provided in the authentication device 1. In particular, the loader 24 has a sensor 62 for detecting the remainder of the paper in the loader, which is a reflective optical sensor, and which detects whether there is still any sheet P of paper in the loader 24. The deflection moment sensor 64, which is an optical a sensor is provided on the side in front of the diverting module 41 in the conveying module 32. The diverting element of the diverting module 41 is moved to one of the positions, so that the P sheet of paper is transferred to the stacking module 36 or the position in which the sheet of paper P is transferred to the ejecting module 40 at the time detected by the sensor 64 of the time of the deviation.

Of the two transport paths that diverge from the place where the deflecting module 41 is located, on the transport path that leads to the stacking module 36, there is a paper passage detection sensor 66, which is an optical sensor, and which detects a paper sheet P transported by ways of transportation. A paper sheet passage detection sensor 66 detects a paper sheet P when the paper sheet P is transported along the conveyance path towards the stacking module 36 through the deflecting module 41.

A paper sheet detection sensor 68 in the stacking module, which is an optical sensor and which detects whether the paper sheet P is stacked in the stacking module 36, is provided in the stacking module 36. The paper sheet detection sensor 70 of the ejecting module, which is an optical sensor and which detects whether the sheet P 'of paper is stacked in the ejecting unit 40 is provided in the ejecting unit 40.

In addition, as shown in FIG. 2, a control unit 14 that controls all the constituent elements of the authentication device 1 is located in the authentication device 1. In particular, the feeding module 26, the transporting module 32, the recognition and counting module 34, the laying module 36, which includes a laying mechanism such as a laying wheel, a deflecting module 41, etc. are all connected to the control module 14.

The fluorescent substance identification module 14a of the control module 14 identifies the ink containing the fluorescent substance that is deposited on a sheet of paper based on the output of the fluorescence sensor 11 located in the recognition and counting module 34. The determination unit 14b of the control unit 14 determines the authenticity of the paper sheet based on the identification result of the ink containing the fluorescent substance output by the fluorescent substance identification module 14a and the output of the other sensors 12.

The control module 14 controls the feeding module 26, the conveying module 32, the stacking module 36, the deflecting module 41, etc., by supplying command signals to these constituent elements based on the result of the authentication of the paper sheet.

In addition, a sensor 62 for detecting a sheet of paper remaining in the loader, a deflection time sensor 64, a paper passage detection sensor 66, a paper detection sensor 68 in the stacking module, and a paper sheet detection sensor 70 in the ejection module are connected to the control module 14, and the output of these sensors is passed to the control module 14. The operation / display unit 42 is connected to the control unit 14. As shown in FIG. 8, the operation / display unit 42 is an operation / display device located on the front side of the housing 22. The processing state of the sheet P of paper processed by the authentication device 1, more specifically, information such as a number representing the face value of the sheets P the paper counted by the recognition and counting unit 34 and the total amount are displayed in the operation / display unit 42. The operator may issue various commands to the control unit 14 using the operation / display unit 42.

The structure of the recognition and counting module 34 shown in Fig. 8 is explained below with reference to Figs. 9A and 9B. On figa and 9B shows a set of drawings representing the structure of the module 34 recognition and counting. On figa presents a drawing of the structure of the module 34 recognition and counting. 9B is a drawing showing an example of placement of a fluorescence sensor 11.

As shown in FIG. 9A, the recognition and counting module 34 includes tracking sensors 301a-301d, a line sensor 302, a magnetic sensor 303, a thickness detection sensor 304, and a fluorescence sensor 11. Tracking sensors 301a-301d, line sensor 302, magnetic sensor 303, and thickness detection sensor 304 correspond to other sensors 12 shown in FIG.

Tracking sensors 301a-301d detect the passage of a sheet of paper. In particular, the tracking sensors 301a and 301b are located on the side in front of the conveying unit 32, and the tracking sensors 301c and 301d are located on the side after the conveying unit 32. After detecting a sheet of paper, the tracking sensors 301a-301d transmit the detection result to the control unit 14. After the sheet of paper is detected by the tracking sensors 301a and 301b, the control unit 14 begins to receive samples from the fluorescence sensor 11, the line sensor 302, the magnetic sensor 303, and the thickness detection sensor 304.

The line sensor 302 receives image data of a sheet of paper. The line sensor 302 stores the acquired image data of a sheet of paper in a storage device not shown. The magnetic sensor 303 reads magnetic information from a sheet of paper. Similar to the line sensor 302, the magnetic sensor 303 also stores information read from a sheet of paper in a memory device not shown.

The thickness detection sensor 304 detects the thickness of the paper sheet, and, like the line sensor 302 and the magnetic sensor 303, stores the detection result in a memory device not shown. The determination module 14b of the control module 14 authenticates a sheet of paper based on the detection results of each of the sensors stored in the storage device and the identification result output by the fluorescent substance identification module 14a.

As shown in FIG. 9B, in the recognition and counting module 34, the LED light source 305 is located in a position opposite to the line sensor 302 (see (B-1) in FIG. 9B). The line sensor 302 obtains image data based on reflected light received from a sheet of paper irradiated by the line sensor 302 and transmitted through light received from a sheet of paper irradiated by the LED light source 305 when the sheet of paper passes by it.

In addition, in the recognition and counting unit 34, the sensor 306 of the transmitted ultraviolet light is located in a position opposite to the fluorescence sensor 11 (see (B-2) in FIG. 9B). The 306 ultraviolet light sensor 306 detects ultraviolet light that passes through a sheet of paper when ultraviolet light is emitted from the fluorescence sensor 11.

The specific operation of the authentication device 1 in accordance with the present embodiment is explained below. The processing procedure in the process of identifying a fluorescent substance performed by the fluorescent substance identification module 14 a is explained first with reference to FIG. 10. 10 is a flowchart of a process for identifying a fluorescent substance in accordance with the present embodiment.

As shown in FIG. 10, in the authentication device 1, when a paper sheet is detected by the tracking sensors 301a and 301b (step S101), the fluorescence sensor 11 starts irradiating with ultraviolet light, which is an excitation light (step S102). Each of the photodetectors 115a-115d of the four-segment photodiode 115 detects, through a band-pass filter 116a or a band-pass filter 116b or a cut-off UV filter 117, light emitted from a sheet of paper as a result of irradiation with ultraviolet light. The output signals from each of the photodetectors 115a-115d are stored in the storage unit 13 as output values AC after processing, respectively, by amplifiers 120a-120c and AD converters 122a-122c.

After that, in the authentication device 1, the fluorescent substance identification module 14a receives the output values AC from the storage module 13 (step S103), and calculates the evaluation value 1 and the evaluation value 2 (step S104). The fluorescent substance identification module 14a then calculates the full evaluation value from the calculated evaluation value 1 and evaluation value 2 (step S105).

After that, the fluorescent substance identification module 14a determines whether the calculated total assessment value is greater than or equal to the predetermined threshold value (step S106), and if so, identifies the ink containing the fluorescent substance that is deposited on the paper sheet as narrow-band ink (step S107), and finish processing. However, if the total evaluation value is less than the predetermined threshold value, the fluorescent substance identification module 14a identifies the ink containing the fluorescent substance that is deposited on the paper sheet as broadband ink (step S108) and ends the processing.

The case where the fluorescent substance identification module 14 a identifies the ink containing the fluorescent substance by comparing each type of evaluation value calculated based on the output values AC from the four-segment photodiode 115 and the predetermined threshold value is explained above. However, the identification method is not limited to this. The authentication device 1, for example, can match the output values AC to previously stored patterns and determine the authenticity of the sheet of paper based on the result of the comparison.

The processing procedure of the aforementioned authentication is explained below with reference to FIG. 11 is a flowchart of another processing procedure performed by the authentication device 1 in accordance with the present embodiment. The above-mentioned templates, which correspond to the determination data, are stored in advance in a specific storage area of the authentication device 1 for each type of paper sheet.

As shown in FIG. 11, in the authentication device 1, after the paper is detected by the tracking sensors 301a and 301b (step S201), the control unit 14 starts receiving data samples from the paper from different types of sensors, namely, the fluorescence sensor 11, the sensor 302 the line and the magnetic sensor 303 (step S202). In this process, the fluorescence sensor 11 begins to irradiate with excitation light, as described in step S 102 in FIG. 10.

After that, in the authentication device 1, after identifying the type of paper sheet based on the output of each sensor (step S203), the control unit 14 performs a collection step (step S204). In the process of collecting the sample data from each sensor is processed in blocks, each block in this case consists of sample data from a given number of lines, multiplied by a given number of channels. In particular, the control unit 14 calculates with respect to the total value of the sample values for a given conveying distance (for example, 10 millimeters (mm)) of a sheet of paper as a block value.

The control unit 14 can also perform normalization by dividing each block value by the average value of the calculated block values. When a block value, such as an output value A or an output value B, is obtained in the calculation, the control unit 14 can also correct the normalized values of the block of the output value A and the output value B using the normalized value of the block of the output value C.

After that, in the authentication device 1, the determination module 14b reads a template corresponding to the identified paper sheet type from the preset storage area (step S205), and calculates the degree of correspondence between the block value calculated based on the output of each sensor and the template (step S206) . The determination unit 14b then determines whether the calculated degree of compliance is greater than or equal to the predetermined value (step S207), and if so (Yes in step S207), determines that the paper sheet is a genuine banknote (step S208) and ends the processing. However, if the degree of compliance is less than the predetermined value (No in step S207), the determination unit 14b determines that the sheet of paper is a fake banknote (step S209) and ends the processing.

The fluorescence sensor 11 shown in FIG. 4 is formed by installing an interior portion module including UV_LED 111, a four-segment photodiode 115, etc., in a frame module that forms a housing. A more specific structure of the fluorescence sensor 11 is explained below with reference to FIGS. 12A and 12B, FIG. 13 and FIG. 14.

The structure of the frame module will be explained first with reference to FIGS. 12A and 12B. 12A and 12B show a set of drawings representing the structure of the frame module of the fluorescence sensor 11. FIG. 12A shows a diagram of a frame module with a surface opposite to a sheet of paper facing down, while FIG. 12B schematically shows a module of a frame with a surface opposite to a sheet of paper facing up.

As shown in FIG. 12A, the frame module 11a is formed by placing the UV transmission filter 112 and the UV reflection filter 113 in the electrical conductive casing 118. As shown in FIG. 12B, the window 114 is located on the surface of the electrical conductive casing 118 opposite to the paper sheet. The conductive casing 118 is made of conductive plastic to prevent data distortion in the output values AC obtained by the four-segment photodiode 115 due to electrostatic noise,

The structure of the internal module of the fluorescence sensor 11 is explained below with reference to FIG. 13 is a drawing showing the structure of an internal module of a fluorescence sensor 11. As shown in FIG. 13, the indoor unit 11b includes UV_LED 111, band pass filters 116a and 116b, a UV cut-off filter 117, and a substrate 119. A photodetector circuit (including a four segment photo diode 115) shown in FIG. 5 is mounted on the back substrate side 119.

FIG. 14 is a drawing showing how the internal module 1 lb is installed inside the frame module 11a. As shown in FIG. 14, the fluorescence sensor 11 is formed to include an internal module 11b, inside the frame module 11a.

When the indoor unit 11b is installed inside the frame unit 11a, the open portion of the frame unit 11a is covered by a substrate 119 on which the indoor unit 11b is mounted, substantially tightly sealing UV_LED 111, bandpass filters 116a and 116b, cut-off UV filter 117, four-segment photodiode, etc. d., inside the frame module 11a.

Thus, in the present embodiment, the negative influence of electrostatic noise on the output values AC of the four-segment photodiode 115 is prevented by installing an internal module 11b, which includes a four-segment photodiode 115 and UV_LED 111, inside the frame module 11a made of an electrically conductive material.

Industrial applicability

As explained above, an authentication device, an authentication method, and a fluorescence sensor, in accordance with the present invention, are useful for differentiating and detecting fluorescent substances that, when they are excited by irradiation with excitation light, emit fluorescent light having peak wavelengths that are adjacent to each other with another, and, in particular, suitable for differentiation and detection of fluorescent substances deposited on one sheet of paper.

Explanation of Reference Number

[0146] 1: authentication device

11: Fluorescence Sensor

11a: Frame module

11b: Inside module

111: UV_LED

112: UV Pass Filter

113: UV Reflector

114: Window

115: Four-segment photodiode

115a: First photo detector

115b: Second photo detector

115s: Third photodetector

115d: Fourth Photo Detector

116a, 116b: Band-pass filter

117: UV cut-off filter

120a-120s: Amplifiers

121a-121s: gain control

122a-122c: AD converter

12: Other sensors

13: save module

14: control module

14a: Fluorescence Identification Module

14b: Definition module

34: Recognition and Counting Module

301a-301d: Tracking Sensors

302: line sensor

303: Magnetic sensor

304: Thickness Detection Sensor

305: LED light source

306: Ultraviolet Transmitter.

Claims (13)

1. An authentication device for a sheet of paper coated with a fluorescent substance, the authentication being based on determining whether the fluorescent light emitted by the fluorescent substance has a broadband spectrum peak or a narrowband spectrum peak, comprising:
an irradiation module configured to irradiate with excitation light a sheet of paper;
a first photodetector configured to detect light of a first wavelength band, which includes a peak wavelength of fluorescent light excited in a fluorescent substance when irradiated with excitation light;
a second photodetector configured to detect light emitted from the same area on the sheet of paper from which the light detected by the first photodetector is emitted, and which is located in a second wavelength band outside the specified narrowband spectrum, but within the specified broadband spectrum, if said narrowband spectrum and said wideband spectrum have the same peak wavelength;
an identification module, configured to identify, based on the output of the first photodetector and the output of the second photodetector, the type of fluorescent substance deposited on a sheet of paper; and
an authenticity determination module, configured to determine the authenticity of a sheet of paper based on an identification result obtained by the identification module. 2. The authentication device according to claim 1, in which the first photodetector and the second photodetector are located in the same plane, so that they perform detection of fluorescent light excited in the same area on a sheet of paper. 3. The authentication device according to claim 1, wherein the identification module is configured to identify the type of fluorescent substance deposited on a sheet of paper if the comparison value obtained from the output of the first photodetector and the output of the second photodetector is greater than or equal to a predetermined threshold value. 4. The authentication device (1) according to claim 1, wherein the identification module is configured to identify a fluorescent substance deposited on a sheet of paper as the first fluorescent substance if the comparison value obtained from the output of the first photodetector and the output of the second photodetector is less than a predetermined threshold value, and identified as a second fluorescent substance emitting a spectrum in a narrower band than the first fluorescent substance, if the comparison value is greater than or equal to the specified threshold value . 5. The authentication device according to claim 1, further comprising a third photodetector configured to detect light that is emitted from the same area on a sheet of paper from which light detected by the first photodetector is emitted, the light being in a third wavelength band including yourself the first wavelength band and the second wavelength band,
wherein the identification module is configured to identify the type of fluorescent substance after correcting the output of the first photodetector and the output of the second photodetector based on the output of the third photodetector. 6. The authentication device according to claim 5, in which the identification module is configured to identify the type of fluorescent substance after correcting the output of the first photodetector and the output of the second photodetector based on the comparison result obtained from the output of the third photodetector and a preset reference value. 7. The authentication device according to claim 5, in which the identification module is configured to identify the fluorescent substance deposited on a sheet of paper as the first fluorescent substance, if the comparison value obtained from the output of the third photodetector based on light from the area where the fluorescent substance is applied, and exiting the third light-based photodetector from the region where the fluorescent substance is not deposited, greater than or equal to the predetermined threshold value, and identify as the second fluorescent substance having f spectrum with a narrower band than the first fluorescent substance, if the comparison value is less than a predetermined threshold value. 8. The authentication device according to claim 5, in which the identification module is configured to identify the type of fluorescent substance deposited on a sheet of paper based on the first evaluation value, which is the comparison value obtained from the output of the first photodetector and the output of the second photodetector, and based on the second evaluation value, which is the comparison value obtained from the output of the third photodetector based on light from the area where the fluorescent substance is deposited, and the output from the third photodetector a light-based detector from an area where a fluorescent substance is not applied. 9. A method of authenticating a sheet of paper coated with a fluorescent substance, the authentication being based on determining whether the fluorescent light emitted by the fluorescent substance has a peak with a broadband spectrum or a peak with a narrowband spectrum, characterized in that:
irradiating a sheet of paper with excitation light;
detecting light emitted from the same area on a sheet of paper when irradiated with excitation light, using the first photodetector, detecting light in the first wavelength band, which includes the peak wavelength of the fluorescent light excited by the excitation light, and using the second photodetector detect light in the second wavelength band, which is located outside the specified narrow-band spectrum, but within the specified broadband spectrum, if the specified narrow-band spectrum and the specified the broadband spectrum has the same peak wavelength;
identify the type of fluorescent substance deposited on a sheet of paper based on the output of the first photodetector and the output of the second photodetector; and
determine the authenticity of the sheet of paper on the basis of the identification result obtained with the specified identification. 10. A fluorescence sensor for detecting a fluorescent substance deposited on a sheet of paper, the detection being based on determining whether the fluorescent light emitted by the fluorescent substance has a peak with a broadband spectrum or a peak with a narrowband spectrum, comprising:
an irradiation module configured to irradiate a sheet of paper with excitation light;
a first photodetector configured to detect light in a first wavelength band that includes a peak wavelength of fluorescent light excited in a fluorescent substance when irradiated with excitation light; and
a second photodetector configured to detect light emitted from the same area on the sheet of paper from which the light detected by the first photodetector is emitted, the light being in a second wavelength band outside the specified narrowband spectrum, but within the specified broadband spectrum, if the specified narrowband spectrum and the specified broadband spectrum have the same peak wavelength. 11. The fluorescence sensor of claim 10, in which
the first photodetector includes a first photodetection element and a first filter which, from light coming from a sheet of paper, transmits only light in the first wavelength band, which includes a peak wavelength of fluorescent light excited by a fluorescent substance,
the second photodetector includes a second photodetection element and a second filter, which from the light coming from a sheet of paper transmits only light in the second wavelength band, which is located next to the first wavelength band,
wherein the first photodetection element and the second photodetection element are located in the same plane, so that they perform photodetection of fluorescent light excited in the same area on a sheet of paper when irradiated with excitation light. 12. The fluorescence sensor of claim 10, further comprising a third photodetector configured to detect light that is emitted from the same area on the sheet of paper from which the light detected by the first photodetector is emitted, and which is in the third wavelength band, the third the band includes a first wavelength band and a second wavelength band. 13. The fluorescence sensor of claim 12, further comprising a frame made of an electrically conductive material, the frame having an internal module that includes a first photodetector, a second photodetector, a third photodetector, and an irradiation module.

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