JPH07239960A - Paper money discrimination device - Google Patents

Abstract

PURPOSE:To improve the accuracy of paper money discrimination by measuring a luminous quantity of a reflected laser beam and controlling a light emitting quantity so that at least the light emitting quantity is not less than a detectable light receiving quantity thereby reducing a change in the reflected luminous quantity. CONSTITUTION:A laser beam generated from a laser emitting section 5 is stopped by a radiation lens 9 and cast on one point in a sensing zone of a paper money 1 as a very small spot light, reflected at an incident point and stopped by a light receiving lens 11 and then reaches a light receiving section 10. In this case, a position of a reflected light of the very small spot light reaching the light receiving face differs due to a very small swell on the paper money 1 due to ink or the like in the sensing zone. Thus, the light receiving section 10 outputs a height signal based on the difference of the arrival position on the light receiving face to a control section 6 sequentially. The control section 6 keeps a current drive current when an output of the light receiving section 10 is between an upper and a lower limit and decreases or increases the drive current when the output is outside the upper and lower limits by the control of a laser beam output from the laser emitting section 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bill discriminating apparatus for discriminating whether or not an object, which is recognized as a bill for appearance, is a genuine bill, and particularly to a partial absorption of near infrared rays in the bill. Despite this, the present invention relates to a bill validator capable of accurately validating bills without causing a shortage of light quantity.

[0002]

2. Description of the Related Art The inventor of the present invention determines the authenticity of a bill by examining whether or not the target bill has a printing portion using a printing technique by intaglio printing which is adopted for genuine bills. Technology has already been proposed (Japanese Patent Application No. 4-
350527 and Japanese Patent Application No. 5-107702). However, these technologies are not yet known at this time.

In any case, for various reasons, at the present time when the technique for identifying the authenticity of banknotes is at a dead end, it is expected that a more accurate banknote identification technique can be proposed. Printing part by the technique of intaglio printing, which is present in genuine banknotes in a certain detection zone,
That is, it is detected whether or not there is a minute swell due to the printing ink generated on the banknote surface by intaglio printing, and the row of presence or absence of the minute swell obtained in the detection zone is the same as that in the same detection zone of the genuine bill. We believe that investigating whether or not they have an approximate relationship will be a banknote identification technology that can break through the deadlocks that have existed so far.

First, for the purpose of comparison, a conventional banknote identification technique and its problems will be described. One of them is to irradiate a bill with light (including infrared rays) along an appropriate detection zone,
The reflected light is received, and the waveform obtained by photoelectrically converting the reflected light is compared with that for genuine banknotes, if it is within a certain allowable range, it is determined as a genuine note, and if not, This is a technique for determining that it is a counterfeit note.

More specifically, among these techniques,
Those that use visible light are letters printed on the surface of bills,
A figure, symbol, or pattern is treated as a planar one, and light is emitted along the appropriate detection zone as described above, and the reflected light that changes depending on the planar pattern is received, and the photodetector photoelectrically converts it. The authenticity is determined by comparing the waveform of the converted electric signal with that of the same detection zone of the genuine bill.

In the case of using infrared rays, as described above, infrared rays are radiated along an appropriate detection zone, and the absorption rate of infrared rays by the paper or printing ink constituting the banknotes is irrespective of the unevenness of the banknote surface. The reflected infrared rays that change depending on the difference are received by the infrared light receiving element, and the waveform of the electric signal photoelectrically converted by the light receiving element is compared with that of the same detection zone of the genuine bill to determine the authenticity.

The above-mentioned conventional techniques are not necessarily denied and have a certain degree of accuracy and have not lost their usefulness. However, with the progress of copy technology, it is becoming more and more difficult to distinguish between a genuine note and a counterfeit note that is a copy of it. Since the counterfeit bills are almost the same in terms of a flat pattern and the like as compared with the genuine bills, almost the same waveforms appear, which makes it difficult to identify.

The technique using infrared light has not been provided so far with devices that copy changes in the absorption rate of infrared light, so that it is more effective than the former technique using visible light. Waveforms with a considerable difference between bills and counterfeit bills are often obtained, and there is still room for identification. However, it is expected that it will gradually come to a dead end for the same reasons as the former, such as progress in copy technology.

Furthermore, when the banknote is soiled by use in the above conventional technique, a flat pattern or the like is used as a basis for identification, so that the identification ability is unavoidably lowered.

In addition to the above, there is a technique for identifying the authenticity by detecting the presence of a magnetic substance in the printing ink. In addition to this, a technique for detecting the width and thickness of banknotes is also adopted. However, these techniques are incomplete and cannot be accurately discriminated from the beginning, and the technique for checking the width and thickness of banknotes is originally only an auxiliary technique.

In view of the above, the present invention provides a banknote discriminating technique capable of surely discriminating between a genuine bill and a counterfeit bill, which is less affected by dirt, regardless of the progress of the copying technique.
As described above, regarding the portion printed by the intaglio printing technique adopted in the banknote, it is identified whether it is the intaglio printing technique or another printing technique, and It aims to establish an identification technology for identifying the authenticity of banknotes.

It is to be noted that establishing the identification technique for identifying whether the corresponding portion of the target bill is printed by the intaglio printing technique or another printing technique is to identify the authenticity of the bill. The grounds that it is effective for are as follows.

That is, almost all the bills of each country are printed by the intaglio printing technique, and all or part of the printed portion of the bill is printed by the intaglio printing technique. On the other hand, counterfeit bills are manufactured by printing techniques other than intaglio printing or copying by a copying machine. The printing technique for producing counterfeit paper is generally lithographic printing, not intaglio printing at all. In the case of manufacturing by copying, it can be said that this is a planographic printing technique, because the image formed by the toner generated on the drum is transferred onto a sheet.

By the way, this technique, that is, detecting whether or not there is a printing portion by the intaglio printing technique on the printing surface of the bill is, after all, detecting the presence or absence of minute swelling due to the printing ink caused by the intaglio printing. There are several techniques for that, but one of them is a disguise method in which a laser generating means for irradiating a laser beam from a diagonal direction is arranged on the surface of a bill, and the bill is placed at an incident point on the bill. The laser receiving means is arranged to cover a certain angle range around the line and the angular position symmetrical with the incident laser beam, and at which position the laser receiving point of the laser receiving means is located. Therefore, it is possible to consider whether or not there is a minute swell at the incident point of the target bill.

If the light receiving position of the laser light receiving means is at a high position, there is a minute swell, and if it is at a low position, there is no minute swell. By relatively scanning the above laser generating means and laser receiving means along a certain detection zone of the target bill,
It is possible to obtain a series of data regarding the presence or absence of minute swelling for the detection zone, and if it is within a certain permissible range as compared with that of genuine bills, it is a genuine bill, otherwise it is a non-genuine bill. It can be determined that

In the above technique, the wavelength of the laser beam cannot be freely selected. For example, visible light is strongly influenced by the color of the bill surface, and the amount of reflected light changes significantly, so it is unsuitable for use in detecting the presence or absence of microscopic swelling, and the near-infrared light with relatively little change in reflected light amount. Is suitable. However, the near-infrared ray also has a slight difference in the degree of absorption depending on the type of printing ink on the bill surface and the like, and when it is irradiated, a change in the reflected light amount cannot be avoided.

[0017]

SUMMARY OF THE INVENTION In the present invention, however, there is provided a bill identifying apparatus for identifying a bill by detecting the microscopic swelling due to the printing ink on the bill surface as described above, which uses a near infrared laser. In the identification device, the change in the amount of reflected light during scanning caused by the positional difference in the absorption rate of near infrared rays in banknotes is reduced at least to the extent that it does not adversely affect the identification of banknotes and the identification accuracy is improved. Letting it be the task of solution.

[0018]

The gist of the structure of the present invention is that the detecting means constituted by a laser generating means and a laser receiving means for generating a laser beam of near-infrared light is fixed on the surface of the target bill. The laser light generated by the laser generating means is irradiated along the detection zone, and the reflected laser light is scanned while being received by the laser light receiving means, and the light receiving position on the light receiving surface of the laser light receiving means is detected. By detecting the presence of a minute bulge on the detection zone, the presence or absence of a minute bulge corresponding to the minute bulge of the printing ink by the intaglio printing on the genuine bill is detected. Comparing the line-up pattern with the line-up pattern of minute swells obtained by scanning the detecting means along the same detection zone in the genuine bill. In a bill discriminating apparatus for discriminating between genuine bills and non-genuine bills, the light amount of the reflected laser light is measured, and at least the light emission amount of the laser generating means is kept so as not to fall below the light receiving amount detectable by the laser light receiving means. A bill validator configured to control the amount, which can solve the above problems.

Various means can be freely adopted for measuring the light quantity of the reflected laser light. For example, the detection of the light receiving position can be performed by the laser light receiving means, and other suitable optical sensors can be adopted. In the former case, for example, if a light receiving means combining a large number of photoelectric conversion elements is adopted as the laser light receiving means, the light receiving position can be specified depending on which photoelectric conversion element receives the light, and thereby the detection zone of the target bill. It is possible to judge whether or not there is a minute swell at the corresponding position in the inside. On the other hand, the amount of reflected light can be measured by measuring the voltage or current converted in the received photoelectric conversion element.

As described above, the control of the laser generating means controls the amount of light emitted from the laser generating means so that it does not fall below at least the amount of light received that can be detected by the laser light receiving means. When the amount of light is less than a certain amount, the amount of light emitted from the laser generating means may be controlled to increase, or the amount of light emitted from the laser generating means may be controlled in inverse proportion to the amount of reflected laser light. It may be done.

The light emission amount of the laser generating means can be controlled by controlling the laser generating means itself or by controlling an amplifier attached thereto.

Regarding the change in the reflected light amount, it may be determined in advance by checking that in the corresponding detection zone of the genuine bill, and based on the data, the laser generating means controls the light amount. By the way, usually, it is unclear in what direction the bill is loaded into the identification device. Therefore, in this case, for example, if the detection zone is determined in the central portion in the length direction of the bill, it is necessary to prepare four types of data in two different directions for the front and back detection zones, Further, it is necessary to immediately detect, by some means, in which direction the detection zone of which surface is being scanned, and to control the laser generating means by corresponding data.

[0023]

Since the present invention is configured as described above, while the target bill is transferred by the transfer means in its length direction, for example,
A laser beam is emitted from a laser generating means arranged above or below the laser beam, and the laser beam is squeezed into, for example, a minute spot so that the bill is irradiated along a certain detection zone with the transfer of the bill. On the other hand, the reflected minute spot light from the detection zone of the target bill is received by the laser light receiving means having a light receiving surface located in the reflection direction and covering the reflection area, while receiving light on the light receiving surface. A signal indicating the position is taken out, and at the same time, the reflected light amount signal at the light receiving position is taken out on the other side.

On the other hand, depending on where on the light-receiving surface of the laser light-receiving means the reflected minute spot light is received, whether or not a minute swell exists at a predetermined position on the detection zone of the target bill. Can judge. On the other hand, the laser generating means is controlled based on the reflected light amount signal. That is, if the amount of reflected light is small, the amount of light generated by the laser is controlled to increase, and if the amount of reflected light is more than necessary, the amount of light generated by the laser is controlled to decrease. It goes without saying that if the amount of reflected light is appropriate, the amount of light generated by the laser is controlled to be maintained as it is.

However, first of all, if it is briefly described from the former, for example, as described above, the presence or absence of minute swells is detected along a certain detection zone of the target bill, and the entire array pattern of the minute swells of the certain detection zone is detected. Is stored in the storage means, and this is compared by the comparison means with the full array pattern of the minute banknotes in the same detection zone of the genuine banknote stored in the storage means, and the result of the comparison, that is, in the full array pattern The matching pattern of each part is input to the judging means, and by this judging means, the arrangement pattern of a certain length or more necessary to obtain the desired identification accuracy is the entire arrangement pattern of the minute swells in the genuine bill. It is determined whether or not it matches the arrangement pattern of the minute swells of the corresponding part of the, and when they match, it is determined that the target banknote is a genuine banknote, and it does not match. It can be determined that the non-genuine bill to the case.

For example, if the identification accuracy required can be obtained if there is a continuous match in a length range of 10 mm in any part of a certain detection zone, such a result is determined by the determination means. When it is obtained, a signal indicating that the bill is genuine is output. If not, naturally, a signal indicating that the bill is a non-genuine bill is output.

In the latter case, that is, in the control of the laser generating means based on the reflected light amount signal, for example, if the light receiving means in which a large number of photoelectric conversion elements are combined is used as the laser generating means, as described above, one of them is used. Depending on which photoelectric conversion element receives the light, the light receiving position can be specified, which makes it possible to determine whether or not there is a minute bulge at the corresponding position in the detection zone of the target bill. By measuring the voltage or current converted by the photoelectric conversion element by the measuring means, the data of the reflected light amount can be obtained.

Then, the laser generating means is controlled based on the value of the reflected light quantity (for example, the value of the voltage or the current) measured. For example, control is performed so as to generate a laser beam whose light amount is in inverse proportion to the reflected light amount, or the laser generating means is controlled so as to return to a predetermined value only when the reflected light amount falls below a predetermined value. As a laser generating means, theoretically, various laser oscillators can be freely adopted, but a semiconductor laser is suitable because of its size, output level, etc., and when a laser diode of a semiconductor laser is used, The amount of generated light is controlled by controlling the drive current.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The bill validator of the embodiment, as shown in FIG.
A conveyance device 3 that conveys a bill 1 inserted from a bill insertion port (not shown) to a stacker (not shown) by passing below the detection part 2 of the minute rise and the detection part 2 described above.
And a control unit 6 for controlling the optical output of a laser generation unit 5 of the detection unit 2 which will be described later, and an identification determination unit 4 for determining the authenticity of the bill 1 based on the detection result of the detection unit 2.

A portion of the transport device 3 located below the detecting portion 2 is a restraining plate for restraining the conveyor belt 7 and the pulleys 8 and 8 around the conveyor belt 7 and the banknote 1 placed on the conveyor belt 7 from above (FIG. (Not shown),
The restraint plate restrains the bill 1 from above so that the bill 1 can pass without undulating. A detection window is opened in the center of the restraining plate.

The detection unit 2 includes the laser emission unit 5 described above.
And the irradiation lens 9 arranged immediately before the light emitting direction,
An irradiation lens 9 for irradiating the detection zone of the bill 1 with a laser beam emitted from the laser emitting section 5 by focusing on a minute spot.
And a light-receiving lens 11 for narrowing the reflected laser light to the light-receiving surface of the light-receiving unit 10 and delivering it, and the light-receiving unit 10. Irradiation and reflection of laser light are performed through a detection window opened in the central portion of the inhibition plate.

The laser emitting section 5 is composed of a laser diode and emits a laser beam having a wavelength of near infrared rays. Further, the light receiving unit 10 is configured by arranging a large number of small photoelectric conversion elements which generate electromotive force upon receiving the near infrared rays. As will be described later, the light receiving unit 10 detects the light receiving position of the reflected laser light that differs depending on the presence / absence of minute bulges on the detection zone of the banknote 1, and detects the presence / absence of minute bulges due to the printing ink for intaglio printing. Is its role. Therefore, it is necessary that the photoelectric conversion elements are arranged so as to form a light receiving position where the reflected laser light is possible, that is, a light receiving surface that covers the reflection area of the reflected minute spot light.

By the way, the laser emitting section 5 emits a laser beam at an angle of about 45 degrees toward the detection zone of the bill 1 passing thereunder, and the light receiving section 10 emits a laser beam of 45 degrees on the opposite side. It is placed at a position where it can receive laser light reflected at an angle.

Further, as shown in FIG. 2, the control unit 6 receives an output from the light receiving unit 10 and compares the output with an upper limit value and a lower limit value, respectively, and an upper limit value comparing unit 12 and a lower limit value comparing unit 13. , Receiving the outputs of the upper limit value storage unit 14 and the lower limit value storage unit 15 and the upper limit value comparison unit 12 and the lower limit value comparison unit 13, respectively,
A determination unit 16 that determines whether the output of the light receiving unit 10 is between the upper and lower limit values, exceeds the upper limit value, or falls below the lower limit value, and the laser emission unit 5 based on the output. And a current control unit 17 that controls the drive current supplied to. In the current control unit 17, the light receiving unit 10
If the output of is between the upper and lower limits, the current drive current is maintained, if it exceeds the upper limit, the drive current is decreased, and if it is below the lower limit, the drive current is reduced. Is controlled so as to increase.

On the other hand, as shown in FIG. 3, the discrimination judging section 4 receives a height signal sequentially detected from the light receiving position of the light receiving section 10, and judges the presence or absence of a small swell. A detection signal storage unit 19 that holds the presence or absence of the minute swells that are sequentially output, and holds all presence or absence signals on the detection zone until the comparison by the next comparison unit 20 is completed. A storage unit 19 and a reference data storage unit 21 that holds a data string that is all-presence or no-signal reference data of minute swells on the genuine banknote detection zone.
A comparing section 20 for comparing the presence or absence of a small swell signal held in the detection signal storage section 19 with a presence or absence signal reference data row in the reference data storage section 21;
An authenticity determination unit 22 that determines whether or not the banknote is a genuine banknote based on a comparison result sequence of a detected or no signal sequence output from 0 and a data signal sequence that is a reference signal, that is, a determination sequence of match / mismatch. The authenticity determination unit 22 is configured to include a determination basic data storage unit 23 that retains the determination basic data that is the basis of the determination so as to be provided.

As shown in FIG. 4, the difference in minute height (presence or absence of minute bulge) in the detection zone of the bill 1 is that the laser beam irradiated to the X height position is the light receiving position of the light receiving unit 10 at the A light receiving position. The laser light reflected on the Y height position and irradiated on the Y height position can be detected by reflecting on the B position of the light receiving unit 10.

Furthermore, if the judgment basic data is consistent with any portion in each of the single or plural detection zones, and how long it coincides with that in the genuine bill, it is recognized as a genuine bill. Data of 10 in this example
mm was determined and stored in the judgment basic data storage unit 23.

In this embodiment, however, when the bill 1 to be identified is inserted into the bill insertion slot (not shown), it is conveyed by the conveying device 3 and passes below the detecting section 2. Below the detection unit 2, the banknote 1 is suppressed from above by the restraint plate (not shown) as described above, and the corrugation is prevented. The laser light generated by the upper laser emitting unit 5 is focused by the irradiation lens 9 and is irradiated as a minute spot light on one point on the detection zone of the banknote 1. The minute spot light is reflected at the incident point on the detection zone, is focused by the light receiving lens 11, and reaches the light receiving surface of the light receiving unit 10.

The minute spot light irradiates at different heights depending on whether there is a minute swell or other swell due to intaglio printing ink on the detection zone of the bill 1 and, as a result, The position where the reflected laser light is narrowed through the light receiving lens 11 and reaches the light receiving surface of the light receiving unit 10 as a minute spot reflected light is different. Therefore, the light receiving unit 10 outputs a height signal based on the difference in the arrival position on the light receiving surface, and the height signal is sequentially input to the control unit 6 and the identification determination unit 4.

At this time, the control unit 6 processes only the magnitude of the output of the light receiving unit 10. That is, the magnitude of the output is compared with the upper limit value or the lower limit value by the upper limit value comparison unit 12 and the lower limit value comparison unit 13, respectively, and the comparison result output is determined by the determination unit 16, and the determination output is received. The current control unit 17 maintains the current drive current when the output of the light receiving unit 10 is between the upper and lower limit values, and reduces the drive current when the output exceeds the upper limit value, and lowers the lower limit. If it is less than the value, it operates so as to increase the drive current, and the laser light output of the laser emitting section 5 is controlled by the drive current.

Needless to say, the upper limit value storage unit 14 and the lower limit value storage unit 15 should store and hold the appropriate upper and lower limit values of the amount of received light in the light receiving unit 10, respectively. . Therefore, the light receiving section 10 always receives the laser reflected light in an appropriate amount of light and ensures accurate detection of the height position.

On the other hand, in the discrimination judging section 4, the judging section 18 judges the presence or absence of a minute swell based on the height signals from the light receiving section 10 which are sequentially received, and the presence or absence of the signal is detected. The outputs are sequentially held in the detection signal storage unit 19.

After that, the presence or absence of minute swells on the detection zone held in the detection signal storage unit 19 is the authentic banknote stored in the reference data storage unit 21 in the comparison unit 20. The reference data of the presence or absence of a minute swell on the same detection zone is compared with each position on each detection zone, and the comparison result is output.

The output signal sequence of the comparison result of the comparison unit 20 is input to the next authenticity determination unit 22, and the output signal sequence is evaluated based on the determination basic data stored in the determination basic data storage unit 23. Then, the authenticity of the target bill 1 is judged.

Since the output of the comparison section 20 is a judgment as to whether or not the minute swells at each position lined up on the detection zone of the banknote 1 coincide with those of the genuine banknote, the comparison result sequence is the same or not. It is a sequence of mismatch signals. However, as described above, in this embodiment, since the judgment basic data is set to 10 mm, the signal string indicating a match in any part of the comparison result string is 10 mm on the detection zone.
If the above is continuous, the authenticity determination unit 22 outputs a signal indicating that the bill is a genuine bill, and if a continuous match of less than 10 mm on the detection zone is obtained, it is determined to be a non-genuine bill. , A signal to that effect is output.

If it is determined in advance that the bill 1 has the appearance as a bill by another identification device or method, the determination that the bill 1 is an authentic bill is close to 100%. That is, as described above, it is unthinkable that a pattern of minute bulges that continuously exists on the detection zone for 10 mm or more coincides with that of a genuine bill, and it is unthinkable for a minute bulge that happens to occur, and non-genuine bills This is because it is not printed by the intaglio printing technique.

[0047]

According to the present invention, a change in the amount of reflected laser light due to a difference in the absorption rate of near infrared rays caused by printing ink, stains, paper quality or other reasons on the detection zone of a bill is changed by the laser receiving means. It can be easily controlled within a range that does not interfere with the reception of light. Therefore, it is possible to ensure high accuracy in identifying bills using near-infrared laser light.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an outline of an embodiment.

FIG. 2 is a block diagram for explaining a control unit.

FIG. 3 is a block diagram for explaining an identification determination unit.

FIG. 4 is an explanatory diagram illustrating a difference in light receiving position on a light receiving surface of a light receiving unit due to a difference in height of an incident position of laser light.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 banknote 2 detection part 3 conveyance device 4 identification determination part 5 laser emission part 6 control part 7 conveyor belt 8 pulley 9 irradiation lens 10 light receiving part 11 light receiving lens 12 upper limit comparison part 13 lower limit comparison part 14 upper limit storage part 15 lower limit Value storage unit 16 Judgment unit 17 Current control unit 18 Judgment unit 19 Detection signal storage unit 20 Comparison unit 21 Reference data storage unit 22 Authenticity judgment unit 23 Judgment basic data storage unit

Claims (2)

[Claims] 1. A laser light generated by said laser generating means along a certain detection zone on the surface of a target bill, comprising a detecting means composed of a laser generating means for generating near infrared laser light and a laser receiving means. Is emitted, and the reflected laser light is received by the laser light receiving means while scanning, and the light receiving position on the light receiving surface of the laser light receiving means is detected. Detecting the presence or absence of minute bulges corresponding to minute bulges of printing ink by intaglio printing on genuine banknotes, the pattern of minute bulges on the obtained detection zone is set along the same detection zone on genuine banknotes. In a banknote discriminating device for discriminating between genuine banknotes and non-genuine banknotes by comparing with an array pattern of minute bulges obtained by scanning of a detecting means. A bill identifying device configured to measure the light amount of the reflected laser light and control the light emission amount of the laser generating means so as not to fall below at least the light receiving amount detectable by the laser light receiving means. 2. The bill discriminating apparatus according to claim 1, wherein the amount of the reflected laser light is measured and the amount of light emitted from the laser generating means is controlled in inverse proportion to the amount of the reflected light.