JPH03235192A - Paper money identifying method - Google Patents

Abstract

PURPOSE:To prevent a genuine paper money recognized erroneously as a forged paper money by deciding a paper money as a counterfeit paper money when it is judged that no value between the upper limit value and the lower limit value of the final pair appears sequentially as the value of a continuous detection signal by a time when the scan of the detecting zone of the paper money targeted to be inspected is completed. CONSTITUTION:It is checked whether or not the value between the upper limit value and the lower limit value of a detecting position in sequence of scan appears in the detection signal of a phototransistor 4b in a sensor unit 4. As a result, when it is judged that no value between the upper limit value and the lower limit value of the final detecting position appears at a time when a signal representing the passage of the paper money 1 detected with a light emitting diode 7c and a phototransistor 7d is outputted, i.e. when no address signal coincides with a reference signal, it is decided that the paper money 1 targeted to be inspected is the counterfeit paper money with a decision means 13. In such a way, it is possible to prevent the genuine paper money recognized erroneously as the counterfeit paper money.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a banknote identification method for identifying the authenticity of banknotes.

[Prior Art] Techniques such as pattern recognition are also used to identify banknotes, but recently, excellent copying devices have become widespread, and these techniques have already been used to distinguish between copied banknotes and genuine banknotes. is becoming difficult.

There is also a technique that uses a magnetic sensor to detect a magnetic pattern made of a magnetic material contained in the printing ink of a banknote, and at the same time detects the dimensions of the banknote and compares them with reference data to identify authenticity.

However, the time-series detection data of a certain detection zone by the magnetic sensor is unstable, as even for the same banknote, the data differs every time it is inspected.

This merely indicates that a magnetic substance exists near a certain position in the detection zone.

Therefore, a method with higher discrimination power uses a sensor unit consisting of a light emitting element and a light receiving element that receives the reflected light.
The banknote to be inspected is scanned along the detection zone, and the light emitted from the light emitting element and reflected at the detection zone of the banknote is detected by the light receiving element. There is an identification method in which position data is compared with corresponding position data (authenticity data) in time-series data of genuine banknotes in the same detection zone, and banknotes are identified based on the difference.

In this method, a scanning position is detected using a rotary encoder, and the detected data and the genuine data at mutually corresponding positions are compared.

[Problems to be Solved by the Invention] Among the conventional examples described above, the method using pattern recognition and the method using a magnetic sensor are difficult to accurately recognize, as is the case with existing methods, and can easily be used to recognize counterfeit banknotes that are not very sophisticated. There is a problem that they may be mistaken for genuine banknotes.

Regarding the last conventional example, there is a problem in how to understand various identification factors in banknotes, especially dimensional factors.
The opposite problem is that there is a high probability that genuine banknotes will be mistaken for counterfeit banknotes.

When examining the dimensional characteristics of banknotes, it is found that the printing positions on the paper surface of banknotes are not all the same, and there are slight deviations in both the vertical and horizontal directions.

A deviation of about 0.5a+m to 4tsva is observed. In addition, the printed surface of worn-out banknotes will wear out and the optical and magnetic properties will change slightly, but moreover, they often shrink due to humidity and other external conditions, and are smaller than new banknotes in the vertical and horizontal directions. It is not uncommon for the time to be as short as 3 ms.

Further, folded and wrinkled banknotes cannot be sufficiently stretched out during identification, so the 2-3- banknotes are essentially in the same state as if they had been shrunk. In addition, with some types of foreign banknotes, the dimensions of the paper are quite different between genuine banknotes, or the vertical and horizontal dimensions of the printing surface are different, so that it can only be assumed that the plates are different.

In addition, when examining the optical, magnetic, and color characteristics of banknotes, it was found that banknotes get dirty during the distribution process after they are issued.
Because they wear out or wear out, we cannot deny that there are large variations in their quality depending on the degree of distribution.

Despite the fact that the identification factor for banknotes to be inspected is as described above, in conventional examples, rotary An encoder is used to detect a precise position, and the data detected at that position is compared with data at the same position on a reference genuine banknote. Therefore, first of all, regarding the detection position, as a result of the print position being slightly shifted vertically and horizontally for each individual banknote, or as a result of slight expansion and contraction during the distribution process, different positions may be mistakenly recognized as the same position. , it is inevitable that the data of those positions will be picked up and compared. Naturally, therefore, it is not easy to check the consistency of the data, and even if considerable software measures are taken, there is a high probability that genuine banknotes will be mistakenly judged as non-genuine banknotes.

Therefore, in the present invention, the conventional banknote identification method shown at the end is improved to enable accurate identification despite the above-mentioned variations in the various identification factors, especially the size factors. The purpose of the present invention is to provide an identification method that does not misidentify genuine banknotes as non-genuine banknotes.

[Means for Solving the Problems] The gist of the configuration of the present invention is to select a part of a banknote as a detection zone for linear detection, and to set a plurality of detection positions from the detection zone in advance to each The value of the detection signal obtained at the detection position is selected such that the value of the detection signal obtained at the detection position is a value that does not match the value of the detection signal that can be obtained between the detection positions before and after the detection position, and at each of the above detection positions. For the value of the detection signal, an upper limit value and a lower limit value are determined for each set of permissible values for genuine banknotes, and furthermore, the upper limit value and lower limit value for each set are stored in a storage means in accordance with the scanning order, and then, The banknote to be inspected is scanned along the selected detection zone with a light emitting element and a light receiving element that receives the reflected light, and the light emitting element emits light toward the detection zone while the light receiving element detects the Detecting the reflected light from the zone, and inputting the detection signal of the reflected light continuously obtained by the light receiving element during the scanning to a comparison means, and in the comparison means, the detection signal of the reflected light continuously obtained by the light receiving element is inputted to the comparison means. It is determined whether or not a value between the upper and lower limit values of each of the sets read in sequential scanning order appears in the detection signal of the reflected light, and the upper and lower limits of the current set are read in the successive detection signals. When a value between the lower limit values appears, the moment the value changes to a value other than the value between the upper limit value and the lower limit value, the comparison means stores the upper limit value of the next set from the storage means. and the lower limit value, and then continues to judge whether or not a value between the upper limit value and the lower limit value appears in the value of the detection signal, until the scanning of the detection zone of the banknote to be inspected is completed. If it is determined that the successive detection signal values appear in sequence up to a value between the upper limit value and the lower limit value of the last set, the banknote to be inspected is determined to be a genuine banknote, and if it is not. In this case, the banknote is determined to be an inauthentic banknote.

The detection zone may be singular or plural. The probability will be higher if there are more than one.

As described above, each detection position in the detection zone should be selected so that the same value as the detection signal value of the detection position does not appear between the detection positions on both sides of the detection position. The above conditions can be satisfied if the peaks and bottoms of the troughs of the waveform obtained by graphing the values of the detection signal continuously obtained during scanning of the detection zone are sequentially selected as detection positions. Dew. Of course, it doesn't have to be this way.

Further, each of the above-mentioned detection positions should be selected by examining a large number of genuine banknotes and selecting a position where the value of the detection signal has relatively little variation.

The upper limit value and lower limit value are determined based on the results of the investigation as described above so as to cover the range of possible genuine banknotes.

As the light emitting element and the light receiving element, a visible light emitting element and a light receiving element may be employed, respectively, but a near infrared light emitting element and a light receiving element are more suitable. here"
"Near infrared rays" refers to infrared rays in the wavelength range of 0.78 μm to 1.5 μm. The light-emitting element and light-receiving element are preferably quantum type devices suitable for use in the near-infrared range. Furthermore, it is appropriate to use a unit type device in which the light emitting element and the light receiving element are integrated.

Furthermore, it is appropriate that the detection zone of the object be scanned by these light-emitting elements and light-receiving elements by moving the bill without moving them.

[Function] Since the present invention has the above configuration, it functions as follows.

The near-infrared light emitting element and the light receiving element are scanned along the detection zone of the banknote to be inspected to obtain continuous detection signals. In this case, the effect is the same whether the light emitting element and the light receiving element are moved or the bill is moved. However, it is appropriate to move the banknotes as described above.

The detection signal that is continuously detected along with the scanning is input to the comparison means, and in the comparison means, the detection signal is compared with each set of upper and lower limit values input from the storage means. It is determined whether the value of has appeared.

In addition, the upper limit value and lower limit value of each set above are as described above,
The information is sequentially read from the storage means into the comparison means in accordance with the scanning order.

Therefore, first, the upper and lower limit values of the set of detection positions to be scanned first are read into the comparison means. The comparison means constantly determines whether or not a value between the upper limit value and the lower limit value appears in the continuously inputted detection signal value, and if so, the continuously inputted detection signal value is continuously inputted. At the moment the value of the detection signal is no longer between those values, the upper and lower limit values of the next set of detection positions are read from the storage means into the comparison means, and the continuously inputted detection signals are compared with them. The detection signal that is continuously input in this way has a value of
It is determined whether the value is between the upper limit value and the lower limit value of the set of detection positions in question, and if so, the upper limit value of the next set of detection positions is determined from the moment when it deviates from that value. Judgment as to whether the value is between the lower limit and the lower limit is started, and the same operation as above is repeated.

As a result of repeating these operations, by the time the scanning of the detection zone of the banknote to be inspected is completed, the successive detection signals will have a value between the upper limit value and the lower limit value of the last set of detection positions. If it is determined that the banknote has appeared, the banknote to be inspected is determined to be a genuine banknote, and if not, it is determined that it is an inauthentic banknote.

Therefore, the detection position is not confirmed using a rotary encoder, but the upper and lower limit values that can be detected at a plurality of predetermined detection positions are determined, and according to the scanning order,
Sequentially, it is determined whether or not a value within the range of the upper limit value and lower limit value of each detection position appears in the detection signal, and a value between the upper limit value and the lower limit value at all detection positions appears in a predetermined order. If so, it is determined that the banknote to be inspected is a genuine banknote, and if not, it is determined that it is not a genuine banknote. Therefore, there is no need to individually confirm the detection positions of the detection zones. As a result, it is possible to eliminate judgment errors caused by uncertain confirmation of the detection position, and it has become possible to more accurately judge authenticity.

[Example] An embodiment of the present invention will be described below based on the drawings.

This embodiment is applied to a vending machine. The mechanism of the vending machine will be omitted.

As shown in Figure 1, the banknote l inserted into the banknote insertion slot
is drawn in by the belt 2 and passes directly under the sensor unit 4 at a constant speed. The belt 2 has a lower light emitting diode 3 placed just in front of it.
When the insertion of the banknote 1 is detected by the phototransistor 3b and the upper phototransistor 3b, the electric motor (not shown) that drives the electric motor starts driving, and the banknote 1 is drawn in as described above. Further, in the belt 2, when it is detected by the lower light emitting diode 3c and the upper phototransistor 3d arranged immediately after that that the banknote l has passed, the electric motor stops driving and the transporting operation stops. It looks like this.

The sensor unit 4 is a reflective photosensor, and includes a light emitting diode 4a that emits near-infrared rays with a peak emission wavelength of 0.94 μm, and a phototransistor 4b that detects the reflected near-infrared rays. As described above,
The light emitting diode 4a also irradiates near-infrared rays onto the detection zone of the banknote 1 passing directly below, and the phototransistor 4b detects the reflected near-infrared rays.

The detection signal of the phototransistor 4b of the sensor unit 4 is connected via a switch 5 to the input terminals of an upper limit comparator 6a and a lower limit comparator 6b.

The switch 5 is turned on when the lower light emitting diode 7a and the upper phototransistor 7b, which are arranged immediately before the sensor unit 4, detect that the tip of the bill l has reached the sensor unit 4. The lower light emitting diode 7c and the upper phototransistor 7d arranged immediately after the sensor unit 4 turn off when the passage of the banknote 1 through the sensor unit 4 is detected. It is.

The upper limit comparator 6a and the lower limit comparator 6b are each constructed from an operational amplifier. In the former case, the output end of the D/A converter 8a is connected to the input end for manually inputting the reference value.
The upper limit value read from the ROM 9a is converted into an analog signal and then input as the reference value. In addition, the latter has a D/A at the input terminal for inputting the reference value.
The output terminal of the converter 8b is connected to convert the lower limit value read from the ROM 9b into an analog signal, which is then input as the reference value.

On the other hand, the upper limit comparator 6a and the lower limit comparator 6b each have an interface circuit 1 that matches their logic levels.
It is connected to each input of an Ex-OR gate (exclusive OR gate) 11 via 0a and 10b.

By the way, the phototransistor 4 of the sensor unit 4
When the output of b is smaller than the reference lower limit value, the outputs of the upper limit comparator 6a and the lower limit comparator 6b become negative, and when they are larger than the reference upper limit, they become positive. Also, if the value is between the upper limit and lower limit,
The output of the former is negative, and the output of the latter is positive. In the interface circuits 10a and 10b, the subsequent stage E
Matching the logic level of the x-OR gate 11, minus is converted to L level and plus is converted to H level.

Therefore, the input of the Ex-OR gate 11 has an L level only when the value of the output signal of the phototransistor 4b of the sensor unit 4 is between the reference upper limit value and lower limit value. and H level signals are respectively input, and the output thereof rises to H level.

Further, the output of the Ex-OR gate 11 is connected to the clock input of the address counter 12. Further, the address signal output of the address counter 12 is output from the ROM 9a.
It is connected to the address input of the ROM 9b and the judgment signal input terminal of the judgment means 13. Note that the above address counter 1
2 is a type of counter that operates on the down edge of the clock input. Further, the address counter 12 includes a light emitting diode 7c arranged immediately after the sensor unit 4.
and is connected so as to be reset by a signal indicating passage of the banknote 1 outputted from the phototransistor 7d. Similarly, a signal indicating the passage of the banknote 1 is connected to be inputted to the determining means 13 as well.

The determining means 13 is composed of a comparator that determines whether or not the reference value signal and the input address signal match.
The reference value signal is given as the number of detection positions in the detection zone, that is, the number of sets of upper and lower limit values. Then, it is determined whether the address signal inputted at the time when the signal indicating the passage of the banknote l is inputted matches the reference value signal, and if they match, the banknote l is a genuine banknote. If not, the banknote is determined to be inauthentic. Note that the above detection position is the sensor unit 4.
In the graph shown in FIG. 2, the output curve of the phototransistor 4b is assumed to be at 13 positions where the output shown by the mark Q occurs. For each of these detection positions, a large number of genuine banknotes are examined, and an upper limit value and a lower limit value are determined for each possible limit, and according to the scanning order by the sensor unit 4, the upper limit value is stored in the ROM 9a and the lower limit value is stored in the ROM 9b. It is assumed that the information is stored in correspondence with each group.

When the paper at to be inspected is inserted from the bill insertion slot, it is detected by the light emitting diode 3a and phototransistor 3b immediately before the belt 2, the belt 2 is driven, and the bill 1 is drawn in the direction of transport. When the tip of the bill l reaches just before the sensor unit 4, it is detected by the light emitting diode 7a and phototransistor 7b placed there, and the switch 5 is turned on.

Therefore, the sensor unit 4 scans the detection zone of the banknote 1 passing directly under it, and the light emitting diode 4a is also irradiated, and the phototransistor 4b detects the reflected light reflected from the detection zone, and its output is The signals are passed through the switches 5 to the upper limit comparators 6a, respectively.
and one of the input terminals of the lower limit comparator 6b. At this point, the address counter 12 has just been reset, so an address signal indicating the first address is output, ROM 9a outputs the upper limit value data of the first detected position, and ROM 9b outputs the upper limit value data in combination with this. The lower limit value data of the first detection position is output.

The upper limit value data is converted into an analog signal by the D/A converter 8a, and the lower limit value data is converted into an analog signal by the D/A converter 8b. These are respectively input to the reference value input terminals of the lower limit comparator 6b.

As described above, until a value between the upper limit value and the lower limit value appears in the output signal of the phototransistor 4b of the sensor unit 4, the outputs of the upper limit comparator 6a and the lower limit comparator 6b are either positive or negative. are available,
As a result, since the outputs of the interface circuits 10a and 10b are also at the H level or L level, the output of the Ex-OR gate 11 remains at the L level. When a value between the above two values appears, the output of the upper limit comparator 6a becomes negative and the output of the lower limit comparator 6b becomes positive, so the outputs of the interface circuits 10a and 10b become L level and H level, respectively. Therefore, the output of the Ex-OR gate 11 rises to H level. At this time, it is estimated that a signal of the same level as that at the detection position of the genuine banknote is detected at the first detection position in the detection zone of the banknote 1 to be inspected.

When the banknote 1 subsequently moves and the value of the detection signal deviates from between the upper limit value and the lower limit value, the outputs of the interface circuits 10a and 10b become L level or H level as described above.
As a result, the output of the Ex-OR gate 11 falls. When this output falls, the address counter 12 counts up at this timing and outputs the address signal of the next address. So ROM9
The upper limit value data and lower limit value data of the next detection position are outputted from the ROM 9b and the upper limit comparator 6a. and is input to the reference value input terminal of the lower limit comparator 6b. After this, it is determined whether or not the value of the detection signal appears between the upper and lower limits of the second detection position.

When a value between the upper limit value and the lower limit value appears in the detection signal, the output of the Ex-OR gate 11 becomes H level as described above, and then when the value of the detection signal becomes a value outside the above range. , the output of the Ex-OR gate 11 falls to the L level. That is, this indicates that the banknote 1 to be inspected outputs the same detection result as a genuine banknote even at the second detection position.

When the output of the Ex-OR gate 11 falls to the L level, the address counter 12 counts up again at that timing and further outputs the address signal of the next address.

As a result, the next upper limit value data and lower limit value data are output from the ROM 9a and ROM 9b, and the same comparison as described above is performed by the upper limit comparator 6a and the lower limit comparator 6b.

In this way, the value of the detection signal of the phototransistor 4b of the sensor unit 4 is compared with the upper and lower limit values of the detection positions in order according to the scanning order, and each time a value between them appears in the detection signal, the next value is compared. A comparison is made with the upper limit value and lower limit value of the detected position in the order of . Therefore, if a value between the upper limit and the lower limit of the last detected position appears in the above detection signal one after another (if a value between the upper limit and the lower limit of the last detected position appears) If the result is positive, it is determined that the banknote is genuine.

During the above operation, pulses corresponding to the number of detection positions where a value between the upper limit value and the lower limit value appears in the detection signal are input to the address counter 12. If the values in between appear in order, that is, if it is determined that the banknote is genuine as described above, the address counter 12 calculates the address next to the address holding the last upper limit value and lower limit value. The address signal shown will be output. This address signal is used for ROM9a and ROM9a.
In addition to b, the determination means 13 is also simultaneously input, and the light emitting diode 7C and phototransistor 7d detect that the banknote 1 has passed immediately after the sensor unit 4, and a signal indicating this is input to the determination means 13. When 13 is input, A at this time.

The dress signal is compared with the reference value signal, and if they match, the banknote is determined to be genuine. In the above case, since they match, it is naturally determined that the banknote is genuine.

Note that the light emitting diode 7C and the phototransistor 7
The signal indicating the passage of the banknote 1 detected at step d is simultaneously input to the address counter 12 and reset.

As a result of checking whether or not a value between the upper limit value and the lower limit value of the detection position in the scanning order appears in the detection signal of the phototransistor 4b of the sensor unit 4, as described above, the light emitting diodes 7c and At the time when the signal indicating the passage of the banknote 1 detected by the phototransistor 7d is output, it is not determined that a value between the upper and lower limits of the last detection position has appeared, that is, If the address signal does not match the reference value signal, the determining means 13 determines that the banknote 1 to be inspected is an inauthentic banknote.

[Effects of the Invention] The present invention performs detection along the detection zone of a banknote, and checks whether a detection signal at a predetermined detection position is a value between an upper limit value and a lower limit value, which are reference values. Furthermore, unlike the conventional example, a rotary encoder is not used to confirm the detected position first.

The upper and lower limit values that can be detected at a plurality of predetermined detection positions are determined, and it is checked whether a value within the range of the upper and lower limit values for each of the detection positions appears in the detection signal according to the scanning order. If a value between the upper and lower limit values appears at all detection positions according to the prescribed order, the banknote to be inspected is determined to be a genuine banknote, and if not, it is determined to be a non-genuine banknote. It is determined that Therefore, there is no need to individually confirm the detection positions of the detection zones. As a result, there is no need to use a rotary encoder, and it is possible to eliminate the errors in judgment caused by uncertain confirmation of the detection position that occur when using a rotary encoder, making it possible to make more accurate judgments. It is something.

Confirming the detection position is extremely difficult, for example, even if the bill is genuine, the printing may be misaligned, it may have shrunk due to moisture, or it may have shrunk due to wrinkles. Normally, the detection position is shifted by using the . Therefore, it is not a problematic method to compare detection signals obtained at such uncertain detection positions (as mentioned above,
By adopting a method of sequential comparison without checking the positions, accurate judgments can be made. Few (
In both cases, it is possible to eliminate the need to judge genuine banknotes as non-genuine banknotes.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; Fig. 1 is a block circuit diagram thereof, and Fig. 2 shows an output curve of a phototransistor of a sensor unit that detects a genuine 1,000 yen bill along the detection zone. It is something that l...Banknote, 2...Belt, 3a, 3c, 4a, 7
a, 7cm light emitting diode, 3b, 3d, 4b, 7b,
7d... Phototransistor, 4... Sensor unit, 5... Switch, 6a... Upper limit comparator, 6b...
...lower limit comparator, 8a, 8b...D/A converter,
9a, 9b-ROM, lOa, 10b-interface circuit, 11...Ex-OR gate, 12.
...Address counter 13...determination means.

Claims (1)

[Claims] A part of the banknote is selected as a detection zone for linear detection, and a plurality of detection positions are detected in advance from the detection zone, and the value of the detection signal obtained at each detection position is determined by The value of the detection signal at each detection position is selected so that the value does not coincide with the value of the detection signal that can be obtained between the detection positions, and each value that is acceptable as that of a genuine banknote is selected. The upper limit value and the lower limit value of each set are determined, and the upper limit value and lower limit value of each set are stored in the storage means in accordance with the scanning order.After that, the banknote to be inspected is detected along the selected detection zone. A light-emitting element and a light-receiving element that receives the reflected light are scanned, the light-emitting element emits light toward the detection zone, the light-receiving element detects the reflected light from the detection zone, and the light-receiving element detects the light reflected from the detection zone. Detection signals of reflected light that are continuously obtained during scanning are input to a comparison means, and in the comparison means, the detection signals of reflected light that are continuously input are sequentially read in the scanning order. It is determined whether a value between the upper limit value and the lower limit value of each of the above groups appears, and if a value between the upper limit value and the lower limit value of the current group appears in the continuous detection signal, the above At the moment when the value changes to a value other than the value between the upper limit value and the lower limit value, the next set of upper limit value and lower limit value is read from the storage means into the comparison means, and then the value of the detection signal is changed to the value of the detection signal. It continues to judge whether a value between the upper limit value and the lower limit value appears, and in this way, by the time the scanning of the detection zone of the banknote to be inspected is completed, the value of the continuous detection signal is sequentially added to the last group. If it is determined that a value between the upper limit value and the lower limit value has appeared, the banknote to be inspected is determined to be a genuine banknote, and if not, it is determined to be an inauthentic banknote. A banknote identification method.