JP2005062968A - Device and method for discriminating paper sheets - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for discriminating paper sheets which is small in shape, low in cost and can discriminate the paper sheets precisely, and to provide a method therefor. <P>SOLUTION: This device is provided with: a light source 2 for irradiating the paper sheet 1 with illuminating lights L; diffraction grating 3 for dispersing reflected light rays R1 and R2 reflected at different angles; four light receiving elements 21 to 24 for outputting electric signals corresponding to the strength of detected lights (dispersed light rays D1 to D4) received through the diffraction grating 3; and an arithmetic processing unit 20 connected to the respective light receiving elements 21 to 24. Also, the paper sheet 1 is conveyed to a predetermined direction to a light source 2. The arithmetic processing unit 20 is configured to calculate the intensity rate of the light rays whose wavelength approximate to each other based on an electric signals in proportion to light quantity P1 to P4 outputted from the two sets of light receiving elements 21, 22 and 23, 24 to discriminate the authenticity of the paper sheet 1 having a color changing part 10. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a paper sheet discrimination apparatus and a paper sheet discrimination method for forming a color change portion in which the color of a reflected color changes according to a viewing angle on a paper sheet and determining the authenticity of the paper sheet. .
[0002]
[Prior art]
In recent years, paper sheets such as banknotes, securities, and gift certificates, or plastic cards such as credit cards and cash cards (hereinafter, these are collectively referred to simply as paper sheets) are forged. Is increasing. As countermeasures, letters / graphics / symbols printed by OVI (Optical Variable Ink), etc. whose brightness / color changes depending on the viewing angle, and letters / graphics / symbols by holograms (hereinafter referred to as these) Simply referred to as a color-changing portion), and there are cases where the paper looks different in color appearance depending on the viewing angle.
[0003]
It is difficult to counterfeit paper sheets having these color changing portions, and providing a color changing portion on a large number of paper sheets to be issued is an effective means for preventing counterfeiting. The discrimination of the color change portion includes discrimination by humans and discrimination by machines. When a person tries to discriminate paper sheets, if the color change portion is observed while tilting the paper sheets, the color of the color change portion changes depending on the viewing direction, so that the authenticity can be easily confirmed.
[0004]
On the other hand, when automatically identifying paper sheets (especially banknotes) inserted into a vending machine, money change machine, or a depositing / dispensing machine such as an unmanned store, etc. The presence / absence of a color change portion is detected by detecting colors from a plurality of directions.
[0005]
The prior art of a discrimination apparatus (hereinafter referred to as a paper sheet discrimination apparatus) that realizes the detection operation of the color change portion provided in such a paper sheet will be described.
FIG. 4 is a configuration explanatory view showing an example of a conventional paper sheet discrimination device. This paper sheet discrimination apparatus includes a light source 2, two sets of lenses 31, 32, optical bandpass filters 41, 42, and two sets of light receiving elements 51, 52 (Patent Document 1).
[0006]
The light emitted from the light source 2 to the paper sheet 1 is reflected by the color changing portion 10, and the light having the reflection angle θ 1 is detected by the light receiving element 51 through the lens 31 and the optical bandpass filter 41. The light having the reflection angle θ2 is detected by the light receiving element 52 through the lens 32 and the optical bandpass filter 42.
[0007]
5A and 5B show light wavelength distribution curves of the reflection angle θ1 and the reflection angle θ2, respectively. The reflected light from the color changing portion 10 has a peak wavelength λ1 at the reflection angle θ1 and a peak wavelength λ2 at the reflection angle θ2. The light receiving element 51 detects the intensity (light quantity) of light in the vicinity of the wavelength λ1 from the reflected light having the reflection angle θ1, and the light receiving element 52 has the wavelength λ2 by the filter 42 out of the reflected light having the reflection angle θ2. The intensity (light quantity) of the nearby light is detected, converted into an electrical signal, and sent to a processing device (not shown). In the processing apparatus, the light quantity for each wavelength is compared based on the electrical signals from the light receiving elements 51 and 52, and the authenticity of the color change portion 10 is determined.
[0008]
In addition, as shown in FIG. 6, another patent document 2 includes two spectrophotometers 6 and 6, and receives light of two wavelengths λ1 and λ2 reflected at different angles θ1 and θ2. An image recording medium that is configured to detect the color of the paper sheet 1 in a wide range, and that determines the authenticity of the color change portion 10 based on a light amount difference at a specific wavelength between the color change portion 10 and other portions. A false discrimination method is disclosed.
[0009]
Further, Patent Document 3 discloses a fluorescence pattern detection that irradiates a medium with ultraviolet light to excite a fluorescent substance contained in the medium, receives fluorescence emitted from the fluorescent substance, and detects the fluorescence pattern. An invention for correcting a decrease in detection level due to a decrease in light emission intensity of a light source in an apparatus is disclosed.
[0010]
[Patent Document 1]
JP 2002-117431 A [Patent Document 2]
JP 2002-274001 A [Patent Document 3]
Japanese Patent Laid-Open No. 2003-6701
[Problems to be solved by the invention]
In these conventional techniques, at least two or more sets of expensive optical parts such as lenses, filters, and light receiving elements are used as in the paper sheet discrimination apparatus shown in FIG. 4, or the authenticity determination method shown in FIG. In addition, an expensive and large spectrophotometer is used. For this reason, there is a problem that these technologies are difficult to be applied to vending machines that are desired to be reduced in cost and size.
[0012]
Further, in the paper sheet discrimination apparatus shown in FIG. 4, a change in the light amount at a specific wavelength in a specific direction, a change in the irradiation wavelength, a change in the light amount reflected by dirt or mischief of the paper sheet, or a light amount change in a specific wavelength occurs. If this happens, there is a risk of outputting an incorrect discrimination result.
[0013]
An object of the present invention is to provide a paper sheet discrimination device and a discrimination method that are small in shape and that can be discriminated at low cost with high accuracy.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, there is provided a paper sheet discriminating device for forming a color change portion in which the color of the reflected color changes according to the viewing angle on the paper sheet and determining the authenticity of the paper sheet. The The paper sheet discrimination device has a light source that irradiates light on the paper sheet from a certain direction and a spectral characteristic corresponding to a reflection characteristic of the color change part, and has a different angle from the color change part. The first and second spectroscopic elements that respectively divide the reflected light and the first and second spectroscopic elements that receive the light separated at different wavelengths are output, and electrical signals corresponding to the respective received light intensity are output. Based on the two sets of light receiving elements and the four electric signals output from the two sets of light receiving elements, the light intensity ratio of the light having wavelengths similar to each other is calculated, and the sheet having the color changing portion is calculated. And an arithmetic processing unit for determining authenticity.
[0015]
In addition, it is possible to provide a paper sheet discrimination method in which a color change portion in which the color of the reflected color changes according to the viewing angle is formed on the paper sheet and the authenticity of the paper sheet is determined. In this paper sheet discrimination method, among the reflected light reflected at different angles from the color change portion, the first and second light receiving elements respectively receive the light dispersed by the first spectral element, The light separated by the second light-splitting element is received by the third and fourth light-receiving elements, respectively, and the light intensity P1 at the first light-receiving element and the third light-receiving element having a wavelength approximate to the light intensity P1. The ratio (P1 / P3) of the light intensity P3 and the light intensity P4 of the fourth light receiving element and the light intensity P2 of the second light receiving element having a wavelength close to that (P1 / P3) P4 / P2) is determined, and the product of the two ratios (P1 / P3) and (P4 / P2) is compared with a reference value in the color change portion to determine the authenticity of the paper sheet. To do.
[0016]
According to the present invention, it is possible to easily and accurately realize a paper sheet discrimination device without using an expensive and large spectrophotometer.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing a paper sheet discrimination device of the present invention, and FIG. 2 is an explanatory diagram showing the principle of the discrimination method of the present invention.
[0018]
As shown in FIG. 1, the paper sheet discrimination apparatus includes a light source 2 for irradiating the paper sheet 1 with illumination light L, and a diffraction grating 3 for spectroscopically reflecting the reflected lights R1 and R2 reflected at different angles. , Four light receiving elements 21 to 24 that output electric signals according to the intensity of the detection light (spectral light D1 to D4) received through the diffraction grating 3, and an arithmetic processing device connected to each of the light receiving elements 21 to 24 20 is provided. Although not shown here, moving means for conveying the paper sheet 1 in a predetermined direction with respect to the light source 2 is provided.
[0019]
The surface of the paper sheet 1 is provided with a color change portion 10 in which the color of the reflected color changes according to the viewing angle, and the illumination light L is irradiated on the color change portion 10 in the discrimination device. With the surface facing the light source 2, the paper sheet 1 is conveyed to a predetermined position. FIG. 2 is a longitudinal sectional view taken along the broken line 11 including the color changing portion 10 of the paper sheet 1, and as shown in this figure, out of the light reflected by the color changing portion 10 of the paper sheet 1. The reflected light R1 having the reflection angle θ1 is incident on the first portion 3a of the diffraction grating 3, and is separated into two spectral lights D1 and D2 to become detection light to the light receiving elements 21 and 22.
Also, the reflected light R2 having a reflection angle θ2 (here, θ2 <θ1) is incident on the second portion 3b of the diffraction grating 3, and is separated into two spectral lights D3 and D4, thereby receiving light. It becomes detection light to the elements 23 and 24.
[0020]
The light source 2 irradiates the illumination light L to a predetermined line (for example, a broken line 11) including the color changing portion 10 of the paper sheet 1 conveyed into the discrimination device. At this time, on the normal printing surface excluding the color changing portion 10 of the paper sheet 1, the peak wavelength (reflection peak wavelength) of the reflected light is determined according to the color of the ink printed there, and viewed from any direction. Looks the same color. On the other hand, of the reflected light from the color changing portion 10 of the paper sheet 1, the reflected peak wavelength is λ1 for the reflected light R1 having the reflection angle θ1, and the reflected peak wavelength is λ2 for the reflected light R2 having the reflection angle θ2. The color looks different depending on the viewing angle.
[0021]
The diffraction grating 3 is a rectangular plate disposed substantially in parallel with the paper sheet 1, and in the first portion 3a, the reflected light R1 incident at the reflection angle θ1 from the color changing portion 10 is reflected at the wavelength λ1. In the second portion 3b, the reflected light R2 incident at the reflection angle θ2 from the color change portion 10 is split into the spectral light D3 having the wavelength λ1 and the spectral light D4 having the wavelength λ2. Spectroscopically. The first portion 3a and the second portion 3b of the diffraction grating 3 constitute one diffraction grating having the same lattice constant, but may be a spectroscopic element composed of different diffraction gratings. .
[0022]
The light receiving elements 21 and 22 are arranged at positions for receiving the spectral lights D1 and D2 split by the first portion 3a of the diffraction grating 3, and output electrical signals corresponding to the received light intensity of the spectral lights D1 and D2, respectively. Is. The light receiving elements 23 and 24 are arranged at positions for receiving the spectral lights D3 and D4 dispersed by the second portion 3b of the diffraction grating 3, and receive electric signals corresponding to the received light intensities of the spectral lights D3 and D4, respectively. Output.
[0023]
FIG. 3 is a diagram schematically illustrating received light intensity at the light receiving elements 21 to 24. The received light intensity of each of the light receiving elements 21 to 24 is detected as light amounts P1 to P4 having a size proportional to the area of the shaded portion.
[0024]
That is, as shown in FIG. 5A, the reflected light R1 having the reflection angle θ1 has a wavelength distribution having a peak value at the wavelength λ1, and the received light intensity of the spectral light D1 by the diffraction grating 3 is the reflection peak wavelength λ1. The received light intensity of the spectroscopic light D2 is defined by the light amount P2 at a wavelength near λ2 different from the reflection peak wavelength λ1. FIG. 2B shows the wavelength distribution in the reflected light R2 at the reflection angle θ2. Unlike the case of the reflected light R1, the wavelength distribution diagram has a peak value at the wavelength λ2, and the received light intensity of the spectral light D3 is defined by the light amount P3 at a wavelength near the wavelength λ1. The received light intensity of D4 is defined by the amount of light P4 at a wavelength in the vicinity of λ2, which is the reflection peak wavelength.
[0025]
The arithmetic processing unit 20 calculates the intensity ratio of light having wavelengths close to each other based on the electrical signals proportional to the light amounts P1 to P4 output from the two sets of light receiving elements 21, 22, and 23, 24, and The authenticity of the paper sheet 1 having the change portion 10 is discriminated.
[0026]
The arithmetic processing unit 20 calculates a color change amount A with respect to the reflection angle represented by the following equation (1). That is, the color change amount A with respect to the reflection angle is calculated by integrating the ratio of the light amounts P1 and P3 detected by the light receiving elements 21 and 23 and the ratio of the light amounts P2 and P4 detected by the light receiving elements 22 and 24, respectively. To do. The color change amount A is not less than a predetermined value defined by the original color of the color change portion 10 formed on the paper sheet 1 and the reflection angles θ1 and θ2 of the two reflected lights R1 and R2. If there is, it is determined that the color change portion 10 read from the paper sheet 1 by this discrimination device is true, and the color read from the paper sheet 1 if the calculated color change amount A is equal to or less than a predetermined value. The change part 10 is determined to be 贋.
[0027]
[Expression 1]
A = (P1 / P3) × (P4 / P2) (1)
In addition, when the reflected light amount of the wavelength λ1 reflected from the color change portion 10 changes α times due to the light amount fluctuation of the light source 2 or the surface contamination of the paper sheet 1, the light amounts P1 and P2 that can actually be received. Respectively change to αP1 and αP2. However, such an increase / decrease in the amount of reflected light does not affect the value of the color change amount A calculated by the above-described equation (1), so that it is possible to reliably eliminate the influence of paper sheet contamination.
[0028]
In FIG. 1 and FIG. 2, a spectroscopic element is constituted by a single diffraction grating 3, and spectroscopic characteristics are defined by the lattice constant. However, different spectral elements having different spectral characteristics may be arranged at the respective light receiving positions of the reflected lights R1 and R2. Further, whether to use a transmissive spectroscopic element or a reflective spectroscopic element for the reflected lights R1 and R2 can be appropriately selected.
[0029]
Next, a paper sheet discrimination method will be described.
In the discrimination method of the present invention, first, a color change portion in which the color of the reflected color changes according to the viewing angle is formed on the paper sheet, and the first spectroscopic element out of the reflected light from the color change portion The first and second light receiving elements receive the light separated by the above.
Next, the reflected light reflected at different angles is dispersed by the second spectroscopic element, and the light is received by the third and fourth light receiving elements, respectively.
[0030]
Reflected light from the color changing portion of the paper sheet may be incident on the first and second spectroscopic elements at the same time or at different timings.
Next, a ratio (P1 / P3) between the light intensity (light quantity) P1 at the first light receiving element and the light intensity (light quantity) P3 at the third light receiving element having a wavelength approximate to that is obtained (P1 / P3). A ratio (P4 / P2) between the light intensity (light quantity) P4 at the fourth light receiving element and the light intensity (light quantity) P2 at the second light receiving element having a wavelength close to that of the fourth light receiving element is obtained.
[0031]
Next, the product of these two ratios (P1 / P3) and (P4 / P2), that is, the color change amount A shown by the above-described equation (1) is compared with the reference value in the color change portion. Note that the size of the reference value is defined by the original color of the color changing portion formed on the paper sheet and the reflection angle of the two reflected lights.
[0032]
If the color change amount A is equal to or greater than a predetermined value defined by the original color of the color change portion formed on the paper sheet 1 and the reflection angle of the two reflected lights, the discrimination device uses the paper sheet. The color change portion read from the paper is determined to be true, and if the calculated color change amount A is equal to or less than a predetermined value, the color change portion read from the paper is determined to be 贋.
[0033]
According to the paper sheet discrimination method executed in such a procedure, the authenticity of the paper sheet can be accurately determined.
[0034]
【The invention's effect】
As described above, according to the paper sheet discrimination apparatus and the discrimination method of the present invention, a plurality of wavelength components are detected for each reflected light having different reflection angles in the color change portion, and each is compared. As a result, even when a change in the wavelength component ratio of the reflected light due to a change in the amount of light of the light source or contamination occurs, the authenticity discrimination of the color change portion can be performed stably.
[0035]
Further, by using a diffraction grating as a spectroscopic element, the apparatus can be inexpensive and downsized.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a paper sheet discrimination device according to the present invention.
FIG. 2 is an explanatory diagram showing the principle of the discrimination method of the present invention.
3 is a diagram schematically showing received light intensity at each light receiving element shown in FIG. 1. FIG.
FIG. 4 is a configuration explanatory view showing an example of a conventional paper sheet discrimination device.
FIG. 5 is a diagram schematically showing received light intensity in a conventional paper sheet discrimination apparatus.
FIG. 6 is a configuration explanatory view showing a paper sheet discrimination device according to another prior art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Paper sheet 2 Light source 3 Diffraction grating 10 Color change part 20 Arithmetic processor 21-24 Light receiving element L Illumination light (theta) 1, (theta) 2 Reflection angle R1, R2 Reflected light (lambda) 1 Peak wavelength (lambda) 2 of reflected light R1 Peak wavelength D1 of reflected light R2 ~ D4 Spectroscopic light

Claims (4)

In the paper sheet discrimination device that forms a color change portion in which the color of the reflected color changes according to the viewing angle on the paper sheet, and determines the authenticity of the paper sheet,
A light source for irradiating light on the paper sheet from a certain direction;
First and second spectroscopic elements each having a spectral characteristic corresponding to a reflection characteristic of the color change part and spectrally reflecting reflected light from the color change part at different angles;
Two sets of light receiving elements that receive light separated into different wavelengths by the first and second light separating elements and output an electrical signal corresponding to each received light intensity;
An arithmetic processing unit that calculates an intensity ratio of light having wavelengths close to each other based on the four electrical signals output from the two sets of light receiving elements, and determines the authenticity of the paper sheet having the color change portion; And a paper sheet discrimination device. 2. The paper sheet discrimination apparatus according to claim 1, wherein the first and second spectroscopic elements are diffraction gratings having the same lattice constant. 2. The paper sheet discrimination apparatus according to claim 1, wherein each of the first and second spectroscopic elements is a diffraction grating having a grating constant corresponding to a reflection angle of incident reflected light. In the paper sheet discrimination method of forming a color change portion in which the color of the reflected color changes according to the viewing angle on the paper sheet, and determining the authenticity of the paper sheet,
Of the reflected light reflected at different angles from the color change portion, the light dispersed by the first light-splitting element is received by the first and second light-receiving elements, and is split by the second light-splitting element. The light is received by the third and fourth light receiving elements, respectively, and the ratio between the light intensity P1 at the first light receiving element and the light intensity P3 at the third light receiving element having a wavelength similar to the light intensity P1 ( P1 / P3), and the ratio (P4 / P2) of the light intensity P4 at the fourth light receiving element and the light intensity P2 at the second light receiving element having a wavelength approximate to the light intensity P4,
The product of the two ratios (P1 / P3) and (P4 / P2) is compared with a reference value in the color change portion,
A method for identifying a paper sheet, wherein the authenticity of the paper sheet is determined.

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