JPH06333124A - Paper money identification method - Google Patents

Abstract

PURPOSE:To improve the discrimination accuracy. CONSTITUTION:A pattern of a reflected light from a true paper money is analyzed in advance and plural sets of detection positions being detection signals of a set of a maximum value and a minimum value are selected from a detection zone and when a detection signal of a reflected light from a check object paper money is inputted to a comparator means 16, a detection signal of a reflected light from a light receiving element 12 is amplified by an amplification factor designated in advance to correct dispersion in the light emitting element and the light receiving elements 12 and inputted to the comparator means 16 and the comparator means 16 compares a difference between the maximum value and the minimum value at a detection position of each set and discriminates whether or not the difference of the detection signal is within preset allowable value and it is discriminated to be a true paper money when the difference is within the allowable value and to be a forged paper money when not within the allowable value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bill identifying method.

[0002]

2. Description of the Related Art In various banks, pachinko parlors, etc., various currency exchange machines equipped with a banknote identification device are widely used. In recent years, however, the copying technology and printing technology have improved, and as a result, counterfeit bills that are seemingly indistinguishable from genuine bills have become widespread, and even bill validators cannot distinguish them, which is a major social problem. For example, the bill identifying method shown in Japanese Patent Application No. 2-312248 is based on the following method. That is, a light-emitting element that emits near-infrared light and a light-receiving element that receives reflected light are scanned on the bill to be inspected and the reflected light is received by the light-receiving element,
This detection signal is input to the comparison means. The detection signal is
However, the detection position is selected in advance to have a plurality of maximum and minimum values of the pattern, and the upper limit value and the lower limit value are set in advance for the detection signal at the detection position. , It is determined whether the detection signal value of the reflected light at each detection position from the bill to be inspected is within the range of the upper limit value and the lower limit value. Is determined.

[0003]

However, the above-mentioned conventional bill identifying method has the following problems. That is, the reflected light from the bill to be inspected varies. It is in consideration of this variation that the determination is made based on whether the detection signal at each detection position is within the predetermined upper limit value or lower limit value as described above. However, not only does the reflected light vary considerably among the new bills, but there is a large difference in the amount of reflected light between the new bill and the old bill. Therefore, if such a large variation is taken into consideration, the width between the upper limit value and the lower limit value must be set to a considerably large value, which causes the inconvenience that the counterfeit bill is mistaken for an authentic bill. In fact, in the conventional case, there is a possibility that a genuine banknote copy product may be determined to be a genuine banknote. Further, if the width between the upper limit value and the lower limit value is set to be small, there is a disadvantage that genuine bills are also determined to be counterfeit bills.

Therefore, the present invention has been made to solve the above problems, and an object of the present invention is to provide a bill identifying method capable of improving the determination accuracy.

[0005]

The present invention has the following constitution in order to achieve the above object. That is, a part of the banknote is selected as a detection zone for linearly detecting the banknote to be inspected, and the light-receiving element that receives the light-emitting element and the reflected light is scanned along the selected detection zone, and from the light-emitting element. Light is emitted toward the detection zone, the light receiving element detects the reflected light from the detection zone, the detection signal of the reflected light obtained by the light receiving element is input to the comparison means, and is input in advance by the comparison means. In a banknote identification method for identifying authenticity by comparing the detected signal pattern of the reflected light of a genuine banknote, the pattern of the reflected light from the authentic banknote is analyzed in advance, and the detection signal becomes a set of a maximum value and a minimum value. Selecting a plurality of sets of detection positions from the detection zone, when inputting the detection signal of the reflected light from the inspection target bill to the comparison means, the detection signal of the reflected light from the light receiving element, In order to correct the variation between the optical element and the light receiving element, the signal is amplified according to a pre-specified amplification factor and input to the comparison means, and the comparison means receives the maximum value and the minimum value of the detection signals at the detection positions of each set. Detects the difference in value, determines whether the difference between the detected signals detected is within a preset tolerance range, and if it is within the tolerance, an authentic bill,
It is characterized in that it is determined as a fake bill when it is out of the allowable value.

[0006]

The difference between the maximum value and the minimum value of the detection signal at the detection position of each set is detected, and it is determined whether or not the difference between the detected signals is within a preset allowable value range, Since it is determined that the bill is a genuine bill if it is within the allowable value and a counterfeit bill if it is outside the allowable value, it is possible to improve the determination accuracy. Further, since the variation between the light emitting element and the light receiving element is corrected and the detection signal from the light receiving element is amplified by the predetermined amplification factor and input to the comparison means, the reference value is kept constant regardless of the element used. It can be set and controlled by a microcomputer.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows a principle diagram, 10 is a light emitting element, 12 is a light receiving element, 14 is an amplifier, and 16 is an arithmetic control unit. 18 indicates a banknote. Near-infrared light is emitted from the light emitting element 10 toward the bill 18, and the reflected light reflected by the bill 18 is received by the light receiving element 12. The detection signal output as a voltage value from the light-receiving element 12 is amplified by the amplifier 14 at a predetermined amplification factor, and the calculation control unit 16
Entered in. The light emitting element 10 and the light receiving element 12 are banknotes 1
Scan on 8 defined straight lines. Since this scanning mechanism can adopt the same mechanism as the conventional one, it will not be described in particular. The element side may be run, or banknotes may be run.

FIG. 2 shows an example of a detection pattern of reflected light from the light receiving element 12. A part of the printing ink for the banknotes is ink that reflects near-infrared light. Depending on the shade of the printing pattern, etc., some maximum values P ₁ , P ₂ , P _{3 are shown.}
And the minimum values L ₁ , L ₂ and L ₃ appear. The positions where the above-described maximum values P ₁ , P ₂ , P ₃ and the minimum values L ₁ , L ₂ , L ₃ appear are set as detection positions. This detection position setting is
It is actually empirically obtained from the detection of the reflected light pattern on the new standard bill and is stored in the memory. The detection position is set using a rotary encoder by starting counting from the printing start position on the scanning line of the bill 18 and counting the positions at which the maximum value and the minimum value appear, and setting the values.

Further, the judgment criterion in the present invention is based on the difference between the detection signals of each pair of the adjacent maximum value and minimum value. _{That, P 1 -L 1 = X 1} , P 2 -L 2 = X 2, P 3 -
The value of L ₃ = X ₃ is used as a reference, and an allowable value obtained empirically by measuring variations in the intensity of reflected light of new bills, old bills, etc. is set, for example, X ₁ = 3 ± 0. 5 (V), X ₂ =
A reference value such as 2 ± 0.4 (V) and X ₃ = 1.8 ± 0.3 (V) is set and stored in the memory. In the detection of the bill to be inspected, the detection signal value at each of the detection positions set above is input to the arithmetic control unit 16 and once stored in the memory, the difference between the adjacent maximum and minimum values is calculated. The difference value and the set reference value are compared,
If it is within the range of the reference value, it is determined as a genuine bill, and if it is outside the reference value, it is determined as a counterfeit bill. If it is a genuine bill, it will be exchanged as it is. If it is determined to be a fake bill, the alarm will be activated, and the bill will be ejected as it is without changing it. The difference between the maximum value and the minimum value of the reflected light is not so different between the new bill and the old bill, and the measurement accuracy is improved.

It is to be noted that the light receiving signal from the light receiving element 12 is amplified by a preset amplification factor and input to the arithmetic control section 16 to correct the variation between the light emitting element 10 and the light receiving element 12 which are semiconductor sensors. This is because. That is, the semiconductor sensor has large variations, the amount of light emission varies with the same power, and the output signal value also varies with the same amount of light received. In order to eliminate this variation, a certain reference light emitting element 10 and light receiving element 12 are selected, and a pattern of reflected light from the reference bill is obtained by this reference element. For that purpose, first, a white paper (blank) is scanned to detect reflected light, then a reference bill is scanned to detect reflected light, and a difference between the two is obtained to obtain a pattern of reflected light from the reference bill. The light emitting element 12 and the light receiving element 12 to be used next determine the pattern of the reflected light from the reference bill in the same manner as above. There is a difference between the obtained patterns due to variations in characteristics between the reference element and the element to be used. In order to eliminate this difference, for example, if the maximum value detected by the reference element is 4V and the detected value by the element to be used is 2V, the amplification factor of the element to be used is set to double, and thus the determination is made. It is amplified by the amplifier 14 with the obtained amplification factor and input to the arithmetic control unit 16. By doing so, the reference value X ₁
= 3 ± 0.5 (V), X ₂ = 2 ± 0.4 (V), X ₃ =
1.8 ± 0.3 (V) can be commonly set, and control by a microcomputer becomes possible.

The reflected light from the bill 18 may be detected only on one side of the bill 18, but the authenticity can be determined more accurately by detecting the reflected light from the front and back sides respectively.
In the above embodiment, the detection with near infrared light was tried, but a visible light sensor may be used. Of course, if the near infrared light sensor and the visible light sensor are provided side by side, the accuracy can be further improved. Although not shown, a sensor for detecting the transmitted light that passes through the bill is also provided, so that the thickness of the bill can be detected by the size of the transmitted light, and it is possible to make a determination when two bills are mistakenly inserted. Also, it can be an element of authenticity determination depending on the thickness of the paper.

Although the present invention has been variously described with reference to the preferred embodiments, the present invention is not limited to these embodiments, and many modifications can be made without departing from the spirit of the invention. Of course.

[0013]

According to the present invention, the difference between the maximum value and the minimum value of the detection signal at the detection position of each set is detected, and the difference between the detected detection signals falls within the preset allowable value range. It is determined whether or not there is, and if it is within the permissible value, it is determined to be an authentic bill, and if it is outside the permissible value, it is determined to be a counterfeit bill, so that the determination accuracy can be improved. Further, since the variation between the light emitting element and the light receiving element is corrected and the detection signal from the light receiving element is amplified by the predetermined amplification factor and input to the comparison means, the reference value is kept constant regardless of the element used. It can be set and controlled by a microcomputer.

[Brief description of drawings]

FIG. 1 shows a block diagram.

FIG. 2 is a graph showing an example of a detection pattern of reflected light.

[Explanation of symbols]

 10 light emitting element 12 light receiving element 14 amplifier 16 arithmetic control unit (comparing means) 18 banknote

Claims (1)

[Claims] 1. A part of a banknote is selected as a detection zone for linearly detecting the banknote to be inspected, and a light-emitting element and a light-receiving element for receiving reflected light are scanned along the selected detection zone, The light emitting element emits light toward the detection zone, the light receiving element detects the reflected light from the detection zone, and the detection signal of the reflected light obtained by the light receiving element is input to the comparison means, and the comparison means In a bill identification method that identifies authenticity by comparing with the detection signal pattern of the reflected light of the genuine bill that has been input in advance, the pattern of the reflected light from the genuine bill is analyzed in advance, and the detection signal has the maximum value and the minimum value. When a plurality of sets of detection positions to be a set are selected from the detection zone and a detection signal of reflected light from the bill to be inspected is input to the comparison means, a detection signal of reflected light from a light receiving element ,
In order to correct the variation between the light emitting element and the light receiving element, the signal is amplified according to a prespecified amplification factor and input to the comparing means, and the comparing means receives the maximum value and the minimum value of the detection signal at the detection position of each set. The difference between the values is detected, and it is determined whether the difference between the detected signals is within a preset allowable value range. If the difference is within the allowable value, it is an authentic bill, and if it is outside the allowable value, the counterfeit A bill identifying method characterized by determining that the bill is a bill.