JPS5911155B2 - Paper sheet discrimination device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a paper sheet discriminating device that optically detects the type and authenticity of banknotes with a watermark pattern applied thereto.

BACKGROUND ART Conventionally, in order to determine the type and authenticity of paper sheets such as banknotes, methods are known in which the printed patterns and colors of paper sheets are optically detected.

However, with this method, it is difficult to identify carefully made forged paper sheets such as color copies obtained using a color copying machine. By the way, the banknotes currently in circulation have a watermark pattern applied to them to prevent counterfeiting.
It is extremely difficult to reproduce this watermark pattern using a color copy or the like to counterfeit banknotes. This invention was made in consideration of the above circumstances, and its purpose is to:
It is an object of the present invention to provide a paper sheet discriminating device which discriminates the type and authenticity of paper sheets by optically detecting a watermark pattern applied to the paper sheets.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In this example, the watermark pattern (Horyuji Temple,
The grid portion 15 of the dream hall (see FIG. 3) is detected by the photoelectric detector 1 (see FIG. 1). As can be seen in the figure, the grating section 15 consists of a plurality of gratings 1516 arranged at regular intervals l. The photoelectric detectors 1 are arranged one above the other with the banknote transfer path 10 in between. It consists of a pair of light emitting element 2 and light receiving element 3.

As a result, banknotes (10,000 yen bills) 5 are thrown into the passage 10 from the slot 11, and are transported at a constant speed by a transport mechanism 20 (not shown) in the direction of the arrow in FIG. When passing, the light emitted by the light emitting element 2 passes through the banknote 5, and the transmitted light is received by the light receiving element 3 and converted into an electrical signal. Note that the purpose of use of the photoelectric detector 1 is different from other photoelectric detectors 2512 and 13 for position detection, which will be described later, and is provided to detect the grid portion 15 of the watermark pattern on the banknote 5. As mentioned above, the watermark pattern of the banknote (10,000 yen banknote) 5 is located approximately at the center of the banknote 5.

30 Then, the photoelectric detector 1 detects the above-mentioned grid portion 1 with the watermark pattern.
In order to reliably detect only the banknote 5 and to reliably determine the type and authenticity of the banknote 5, two sets of position detection photoelectric detectors 12 and 13 are provided along the transport direction of the banknote 5. ing. These photoelectric detectors 35 12 and 13 are both constructed similarly to the photoelectric detector 1. The front end 5a of the banknote 5 being transported at a constant speed in the direction of the arrow is detected by the photoelectric detector 12.
A control signal C for validating the detection signal [FIG. 4A] output from the photoelectric detector 1 during the period from when the front end 5a is detected by the photoelectric detector 13 until the front end 5a is detected by the photoelectric detector 13.
is created by a circuit (not shown) using position detection signals output from both photoelectric detectors 12 and 13. In this embodiment, in order to improve the detection ability (resolution) when the photoelectric detector 1 detects the grating portion 15, the slit plate 4 in which one linear slit 17 is formed is connected to the light emitting element 2. It is provided between the light receiving element 3 and the light receiving element 3.

The slit width (width of the opening) of the slit 17 is made to be smaller than the width 2 between the gratings 16, and the length direction of the slit 17 and the length direction of each grating 16 are made to match. The slit plates 4 are arranged like this.
Watermark grid portion 1 detected by photoelectric detector 1
The detection signal No. 5 is input to the amplifier 6 and amplified, and then input to the respective first input terminals of the upper limit voltage comparator 7 and the lower limit voltage comparator 8.

The second input terminal of the upper limit voltage comparator 7 is connected to the power supply E, (voltage R1
) is connected to the lower limit voltage comparator 8, and a power source E2 (voltage VR2; VR2<VR,) is connected to the second input terminal of the lower limit voltage comparator 8. The upper limit voltage comparator 7 compares the output voltage of the amplifier 6 with the voltage R1, and outputs a signal K of the 1111 signal at a binary logic level if the voltage VR1 is negative. Further, the lower limit voltage comparator 8 compares the output voltage of the amplifier 6 with the voltage R2, and if the voltage R2 is smaller, the lower limit voltage comparator 8 outputs a signal K2 of the 111 signal.
Output. Both the signal K1 and the signal K2 are input to the discrimination circuit 9. The discrimination circuit 9 operates only when the control signal C is a 111W signal (that is, the photoelectric detector 1 is detecting the watermark grid portion 15), and during the period when both the signal K1 and the signal K2 are 117 signals. That is, as shown in FIG. 4A, when the output voltage of the amplifier 6 is continuously between the voltages R1 and VR2, a pulse signal with a width proportional to that period is generated as shown in FIG. 4B. This pulse signal is counted by a built-in counter to determine whether the final count is within a predetermined range, and if the count is within a predetermined range, the It is configured to output a discrimination signal indicating that the banknote 5 is a genuine banknote. In this way, the voltages Rl and R2 are such that the output voltage of the amplifier 6 is between the voltage VRl and the voltage R2 when the photoelectric detector 1 detects the area between the gratings 16 in the transparent grating portion 15. , the output voltage of the amplifier 6 is selected to be less than the voltage VR2 when the photoelectric detector 1 detects the grating 16, and when the photoelectric detector 1 detects a portion other than the watermark pattern,
Is the output voltage of the amplifier 6 higher than or equal to the voltage VRl?
The voltage is selected as a value that is less than 2 and cannot be continuously between the voltages VRl and VR2. Note that the symbol in Figure 4 A. indicates the reference voltage. Next, the operation of the above embodiment will be explained.

When a genuine 10,000 yen bill is inserted into the slot 11 of the bill transfer path 10, the bills 5 begin to be transferred in the direction of the arrow. When the front end 5a of the banknote 5 reaches the photoelectric detector 1, the banknote detection signal of the photoelectric detector 1 starts to be output, but until the front end 5a of the banknote 5 reaches the photoelectric detector 12 for position detection, the The control signal C is a 101 signal, and the discrimination circuit 9 does not operate. When the front end portion 5a begins to be detected by the photoelectric detector 12, the control signal C becomes the Wlrl signal, and from this time on, the grid portion 15 of the watermark pattern of the banknote 5 begins to be detected by the photoelectric detector 1. During the transfer period of the banknote 5 from when the front end portion 5a is detected by the photoelectric detector 12 to when the front end portion 5a is detected by the photoelectric detector 13, the control signal C is held at the 1211 signal to enable the discrimination circuit 9 to operate, Also, during this period, the grid portion 15 of the watermark pattern is detected by the photoelectric detector 1, and the amplifier 6 outputs a signal as shown in FIG. 4A. This signal is input to the upper limit voltage comparator 7 and the lower limit voltage comparator 8, and the voltages R,
, voltage R2. As mentioned above, the output voltage of the amplifier 6 while the photoelectric detector 1 is detecting between the gratings 16 of the grating portion 15 is a continuous value between the voltage R1 and the voltage VR2, and therefore Signals K, , K2 output from comparators 7 and 8 are both 5511 signals. At this time, the discrimination circuit 9 generates a pulse signal having a width as shown in FIG. 4B, and counts the pulse signal using a built-in counter.
When the front end 5a of the banknote 5 finishes passing through the photoelectric detector 13, the entire grid portion 15 is detected by the photoelectric detector 1, and at the same time, the control signal C becomes the 1W01W signal and the operation of the discrimination circuit 9 is stopped. At the time of stopping the operation, the discrimination circuit 9 discriminates that the contents of the counter are within a predetermined range associated with genuine banknotes, and outputs a genuine banknote discrimination signal. When the inserted banknote is a fake banknote, the control signal C becomes the 11111 signal in the same way during the period from when the front end 5a of the fake banknote 5 is detected by the photoelectric detector 12 until it is detected by the photoelectric detector 13. The discrimination circuit 9 operates, but the output voltage of the amplifier 6 during this period is not a voltage as shown in FIG. 4A, but the highest voltage is the voltage VR.
1, and the lowest voltage is less than or equal to voltage VR2.

Therefore, after the above-mentioned period has elapsed, the count value of the coefficient unit in the discriminating circuit 9 is outside the predetermined range associated with genuine banknotes. No discrimination signal is output. Therefore, it is determined that the inserted banknote is a counterfeit banknote. In the above embodiment, the level of the detection signal of the photoelectric detector that detects the watermark pattern portion and other portions of the paper sheet is equal to the continuous period between the first and second set levels. A pulse signal with a certain width is created and this pulse signal is counted.However, a pulse signal of a predetermined frequency is always generated from a pulse generator, and this pulse signal is counted by a counter only during the above period. You can configure it as you like.

Furthermore, the present invention is not limited to the above-mentioned embodiments, and the above-described first and second setting levels, the configuration of the discrimination circuit, the shape of the slit, etc. can be changed depending on various watermark patterns on paper sheets. Furthermore, by combining a plurality of circuits of the above embodiments, it is possible to discriminate between types of paper sheets having different watermark patterns. As described above, the present invention provides a paper sheet discriminating device for discriminating paper sheets with a watermark pattern, in which a light emitting element and a light receiving element are disposed vertically across a transport path for the paper sheet. a watermark pattern detector consisting of an element;
a slit arranged in front of the light receiving element and having a width narrower than the details of the watermark pattern; and a position detector that detects a period during which the watermark pattern passes through the watermark pattern detector;
The present invention further comprises a discriminating means for discriminating the details of the watermark pattern based on the alternating current component of the signal output from the light receiving element during the passing period, and discriminating the paper sheet based on this. Strict discrimination is now possible, such as determining the authenticity of elaborately made fake paper sheets, such as those made by copying with a color copying machine, and paper sheets with different types of watermark patterns. This method has the advantage of being able to reliably identify the type of the class.

In particular, by changing the slit shape to match the watermark pattern, sophisticated and accurate discrimination can be easily and inexpensively performed.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a block diagram showing the overall configuration of an apparatus according to the same embodiment, FIG. 2 is a plan view of a paper sheet transfer path of the same embodiment, and FIG. A schematic diagram of a watermark pattern and FIG. 4 are operational waveform diagrams of the same example. 1... Photoelectric detector for watermark pattern detection, 2...
...Light emitting element, 3... Light receiving element, 4...
...Slit plate, 5...Paper leaf, 6...
・Amplifier, 7, 8... Voltage comparator, 9...
... Discrimination circuit, 10 ... Paper sheet transfer path, 12
, 13... photoelectric detector for position detection, 17...
・Slit.

Claims (1)

[Claims] 1. In a paper sheet discrimination device for discriminating paper sheets with a watermark pattern, a watermark pattern detector comprising a light-emitting element and a light-receiving element arranged vertically across the transport path of the paper sheet. a slit arranged in front of the light receiving element and having a width wider than the details of the watermark pattern; a position detector for detecting a period during which the watermark pattern passes through the watermark pattern detector; A paper leaf discrimination device comprising a discrimination means for discriminating the details of the watermark pattern based on the alternating current component of the signal output from the light receiving element, and discriminating the paper leaf based on this. Device.