JPH0579675U - Paper sheet identification device - Google Patents

Abstract

(57) [Summary] [Purpose] Color-copied paper sheets are reliably detected as counterfeit. [Structure] The first subtraction circuit 40 includes a first light receiving sensor circuit 1
The intensity of light having a wavelength of 520 nm detected at 0 and the intensity of light having a wavelength of 950 nm detected by the third light receiving sensor circuit 30 are compared and subtracted, and the difference is output as a voltage value. Second
The subtraction circuit 50 detects the intensity of light having a wavelength of 570 nm detected by the second light receiving sensor circuit 20 and the third light receiving sensor circuit 30.
The intensities of the light having the wavelength of 950 nm detected in step S1 are compared and subtracted, and the difference is output as a voltage value. The third subtraction circuit 60 compares the differences. By the way, in the case of a fake bill, the reflection intensity at the wavelength of 520 nm is larger than that at the wavelength of 570 nm, which is the opposite of the true bill. That is, I1> I3. Therefore, ln (I3 / I1) is negative, that is, TP
If 3 is detected as a negative voltage, it can be determined to be a fake bill.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a paper sheet identification apparatus for identifying paper sheets such as banknotes, and more particularly to a paper sheet identification apparatus that can reliably detect color-copied paper sheets.

[0002]

[Prior Art]

 Recently, copying technology has advanced, and it is now possible to obtain color copies that are almost the same as the original. By the way, since a color sensor is generally used in a device for identifying paper sheets such as banknotes, paper sheets copied in black and white can be reliably detected. It is detected by utilizing the large amount of reflected light in the infrared region (described in JP-A-58-109989).

[0003]

[Problems to be solved by the device]

 However, depending on the type of color copier, the amount of reflected light in the infrared region was not very large. Therefore, there is a problem in that the paper sheets color-copied by such a copying machine are judged to be genuine paper sheets by the conventional paper sheet identification device.

The present invention has been made under the circumstances as described above, and an object of the present invention is to provide a paper sheet identification apparatus capable of reliably detecting a color-copied paper sheet as a counterfeit note. It is in.

[0005]

[Means for Solving the Problems]

 The present invention relates to a paper sheet identifying apparatus for identifying paper sheets such as banknotes, and the above object of the present invention is to provide a light emitting means for irradiating a paper sheet with light and a reflected light from the paper sheet. Of the reflected light from the paper sheet and the light having a wavelength of about 570 nm, and receiving the intensity information. Based on the intensity information output from each of the second light receiving means for outputting, the first light receiving means, and the second light receiving means, it is determined whether or not the paper sheets are color-copied. This is achieved by providing a determining means for determining.

[0006]

[Action]

 In the present invention, in the case of a color-copied counterfeit note, the intensity of the light of the wavelength of 520 nm is larger than that of the light of the wavelength of 570 nm in the reflected light, and the reflection intensity of both wavelengths is detected. Then, the color-copied counterfeit bills can be identified by making a comparison.

[0007]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 3 is a diagram showing the difference in the reflection spectral characteristic between the genuine bill and the counterfeit bill, and particularly shows the reflection spectral characteristic of the chrysanthemum pattern portion of the 5,000 yen bill. There are two types of characteristics of genuine tickets: circulation tickets and government-sealed tickets, and as counterfeit tickets, there are two types of distribution tickets by two color copy machines (A and B machines), which cannot be detected by the conventional method. The characteristics of counterfeit bills are listed.

As shown in FIG. 3, in the case of a genuine bill, the reflection intensity monotonically increases in the range of 400 nm to 800 nm, whereas in the case of a counterfeit bill, there is a portion where it decreases. Specifically, in the case of the counterfeit bill by the machine A, it is reduced at 500 nm to 560 nm, and in the case of the counterfeit bill by the machine B, it is reduced at 525 nm to 575 nm. Therefore, by grasping this characteristic part, it becomes possible to discriminate a fake note, which was impossible with the conventional method.

FIG. 1 is a diagram showing a schematic configuration of an embodiment of a paper sheet identifying apparatus of the present invention. Here, the 1st zone filter 1 and the 2nd zone filter 2 are filters which filter the zone of 520 ± 5 nm and 570 ± 5 nm, respectively. Of the reflected light from the paper sheets, the light having a wavelength near 520 nm passes through the first band-pass filter 1 and is received by the first light receiving sensor 3. The light received by the first light receiving sensor 3 has its intensity information converted into an electric signal, amplified by the first amplifier 5, and then input to the comparison / discrimination means 7. On the other hand, of the reflected light from the paper sheets, the light having a wavelength near 570 nm passes through the second band-pass filter 2 and is received by the second light receiving sensor 4. The light received by the second light receiving sensor 4 has its intensity information converted into an electric signal, amplified by the second amplifier 6, and then input to the comparison / determination means 7. The comparison / discrimination means 7 compares the magnitudes of the input light intensity signal having a wavelength near 520 nm and the input light intensity signal having a wavelength near 570 nm, and outputs a signal according to the result.

FIG. 2 is a circuit diagram showing a detailed configuration of an embodiment of the paper sheet discriminating apparatus of the present invention. This circuit comprises a first light receiving sensor circuit 10, a second light receiving sensor circuit 20, a third light receiving sensor circuit 30, a first subtracting circuit 40, a second subtracting circuit 50, a third subtracting circuit 60, and a constant voltage generating circuit 70. ing. Furthermore, the first light receiving sensor circuit 10 comprises a photodiode 11, an operational amplifier 12, a diode 13 and a capacitor 14, and the second light receiving sensor circuit 20 and the third light receiving sensor circuit 30 are similar. Although not shown, the photodiode 11, the photodiode 21, and the photodiode 31 are provided with filters for filtering the bands of 520 ± 5 nm, 950 ± 5 nm, and 570 ± 5 nm, respectively. The first subtraction circuit 40 is composed of a subtractor composed of resistors 41, 42, 43 and 44, an operational amplifier 45, a voltage follower 46 and a variable resistor 47. The same applies to the second subtraction circuit 50 and the third subtraction circuit 60.

Therefore, the currents flowing through the photodiode 11, the photodiode 21, and the photodiode 31 are I 1, I 2, and I 3, respectively, and the first light receiving sensor circuit 10, the second light receiving sensor circuit 20, the third light receiving sensor circuit 30, and the third light receiving sensor circuit 30 The output voltages of the first subtraction circuit 40, the second subtraction circuit 50 and the third subtraction circuit 60 are V01, V02, V0 3, TP1, TP2 and TP3, respectively, and the resistors 41, 42, 43, 44, 51, 52, 53, 53, The resistance values of 54, 61, 62, 63, 64 are R41, R42, R43, R44, R51, R52, R53, R54, R61, R62, R63, R64. Regarding the output voltages V01, V02, and V03, for example, the voltage V01 is represented by Formula 1.

[0012]

## EQU00001 ## V01 = Vref- (kT / q) .ln (I1 / I0) where k: Boltzmann's constant T: absolute temperature q: electron charge Further, the output voltage TP1 is expressed by equation 2 (V47 = 0).

[0013]

TP1 =-(R42 / R41) .V01 + ((R41 + R42) / R41). (R44 / (R43 + R44)). V02 where R41 = R43, R42 = R44 and V01 and V02 are substituted. , Equation 3 is obtained.

[0014]

TP1 = (R42 / R41). (V02-V01) = (R42 / R41). (KT / q). (Ln (I1 / I0) -ln (I2 / I0)) = (R42 / R41 ) · (KT / q) · ln (I1 / I2) Further, when R51 = R53 and R52 = R54, the output voltage TP2 is similarly expressed by the equation 4 (V57 = 0).

[0015]

TP2 = (R52 / R51) · (kT / q) · ln (I3 / I2) Further, for the third subtraction circuit 60 having the input voltage TP1 and TP2 and the output voltage TP3, R61 = R63 , R62 = R64, it is derived as Equation 5 (V6 7 = 0).

[0016]

## EQU00005 ## TP3 = (R62 / R61). (TP2-TP1) = (R62 / R61). (KT / q). ((R52 / R51) .ln (I3 / I2)-(R42 / R41). ln (I1 / I2)) Here, when R41 = R51 and R42 = R52 are further set, the output voltage TP 3 is finally obtained as Expression 6.

[0017]

TP3 = (R62 / R61) * (R42 / R41) * (kT / q) * ln (I3 / I1) Then, as shown in Expression 3, the first subtraction circuit 40 outputs the light of the wavelength of 520 nm. The intensity and the intensity of light having a wavelength of 950 nm are compared and subtracted, and the difference is output as a voltage value. Further, as shown by the equation 4, the second subtraction circuit 50 compares and subtracts the intensity of light having a wavelength of 570 nm and the intensity of light having a wavelength of 950 nm, and outputs the difference as a voltage value. Further, the third subtraction circuit 60 compares the differences. Therefore, the third subtraction circuit 60 eventually compares and subtracts the intensity of the light having the wavelength of 520 nm and the intensity of the light having the wavelength of 570 nm as shown in the equation (6).

By the way, as described above, in the case of a fake note, the reflection intensity at the wavelength of 520 nm is larger than that at the wavelength of 570 nm, which is the opposite of the true note. That is, I1> I3. Therefore, in Equation 6, if ln (I3 / I1) is detected as a negative voltage, that is, TP3 is detected as a negative voltage, it can be determined that it is a counterfeit note. In the above example, the difference between the intensity of light having a wavelength of 950 nm and the intensity of light having a wavelength of 950 nm is once taken, but it goes without saying that the intensity of light having a wavelength of 520 nm and the intensity of light having a wavelength of 570 nm may be taken.

[0019]

[Effect of the device]

 As described above, according to the paper sheet identifying apparatus of the present invention, color-copied paper sheets can be reliably detected as counterfeit notes, and thus crimes using them can be effectively prevented.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an embodiment of a paper sheet discriminating apparatus of the present invention.

FIG. 2 is a circuit diagram showing a detailed configuration of an embodiment of the paper sheet identifying apparatus of the present invention.

FIG. 3 is a diagram showing a difference in reflection spectral characteristic between a genuine note and a counterfeit note.

[Description of Reference Signs] 1 first band-pass filter 2 second band-pass filter 3 first light-receiving sensor 4 second light-receiving sensor 5 first amplifier 6 second amplifier 7 comparison / determination means 10 first light-receiving sensor circuit 11 photodiode 20th 2 Light receiving sensor circuit 21 Photodiode 30 Third light receiving sensor circuit 31 Photodiode 40 First subtraction circuit 50 Second subtraction circuit 60 Third subtraction circuit 70 Constant voltage generation circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Creator Yumi Ishino 1-3-1 Shimoteno, Himeji City, Hyogo Prefecture Glory Industry Co., Ltd.

Claims (1)

[Scope of utility model registration request] 1. A light emitting means for irradiating a paper sheet with light, and a first light receiving means for receiving light having a wavelength near 520 nm among reflected light from the paper sheet and outputting intensity information thereof. Second light receiving means for receiving light having a wavelength in the vicinity of 570 nm among the reflected light from the paper sheet and outputting intensity information thereof;
And a discriminating unit for discriminating whether or not the paper sheet is color-copied based on the intensity information output from each of the first light receiving unit and the second light receiving unit. Characteristic paper sheet identification device.