JPS63247895A - Paper money discriminator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Summary of the Invention Authenticity of banknotes is determined by detecting irregularities caused by printing on the banknotes. It is possible to eliminate counterfeit banknotes created by magnetic copying, color copying, etc., and also to detect stacking of two banknotes, adhesion with Sellotape, etc.

BACKGROUND OF THE INVENTION The present invention relates to a banknote discriminating device for determining the authenticity of banknotes.

Conventional techniques for determining authenticity of banknotes include those based on magnetic pattern detection, one-color pattern detection, and external shape (dimension) detection, and these have been used singly or in combination. However, with the recent development of copy machines, the reliability of the conventional technology for determining the authenticity of banknotes has been questioned. This is because magnetic copy machines and color copy machines are commercially available, and it is becoming possible to copy magnetic patterns and color patterns that are similar to banknotes using these copy m-machines. be. Detecting the outer shape has only a secondary meaning in determining the authenticity of banknotes, and is not decisive.

The reduced reliability of magnetic pattern discrimination and two-color pattern discrimination means that it is becoming increasingly difficult to reliably determine the authenticity of banknotes. Therefore, there is a need to create a new technology that extracts new features of two banknotes and uses these features to determine authenticity.

SUMMARY OF THE INVENTION An object of the present invention is to provide a device for determining authenticity from a new perspective by utilizing the unevenness caused by printing on nine banknotes.

The banknote discriminating device according to the present invention includes a thickness sensor that detects unevenness on a banknote and outputs a detection signal representing the unevenness, and a detection signal output from the thickness sensor while the banknote is being conveyed. The present invention is characterized by comprising means for determining the authenticity of a banknote by obtaining data representing the uneven pattern of the banknote and comparing the data with a reference pattern.

The bill authenticity determining means may be one that performs normal pattern matching, or may be configured as follows, for example. That is, this discrimination means includes means for respectively detecting the number of times the detection signal exceeds a predetermined main reference level and the number of times the detection signal falls below a predetermined lower reference level, and each detects the number of times the detection signal exceeds a predetermined main reference level and the number of times it falls below a predetermined lower reference level. Using the results obtained by comparison.

Determine the authenticity of banknotes.

This invention takes advantage of the fact that many uneven patterns are produced on banknotes due to the printing of the two banknotes, and uses this new feature of the unevenness to determine the authenticity of banknotes. It goes without saying that other features of a banknote, ie, the above-mentioned magnetic pattern discrimination, single-color pattern discrimination, and external shape discrimination, can be used together to obtain the final result of determining the authenticity of a banknote.

Magnetic copy notes and color copy notes do not have the feature of uneven patterns printed on banknotes, or even if they do, they are different from those of banknotes, making it possible to determine the authenticity of a single banknote.

In addition, since the thickness of one banknote is detected, it is possible to detect when two or more banknotes are being conveyed in an overlapping state, that is, to detect two or more banknotes, and by establishing an appropriate discrimination algorithm, it is possible to It will also be possible to detect the presence or absence.

DESCRIPTION OF THE EMBODIMENTS FIG. 1 shows a mechanism for obtaining a banknote thickness detection signal.

The banknote transport path 10 consists of a number of transport rollers 11, 12 and, if necessary, belts which are placed over these. A detection roller 13 is provided opposite to the conveyance roller 12 . This detection roller 13 is rotatably provided at one end of the roller/<-14. The lever 14 is swingably supported at its midpoint, and the other end is biased by a tension spring 16 in a direction in which the detection roller 13 comes into contact with the conveyance roller 12.

When a banknote B or other medium enters between the rollers 12, 13, the roller 13 is displaced away from the roller 12 by an amount corresponding to its thickness. Therefore, lever 1
The other end 14a of the banknote 4 is displaced in the opposite direction by an amount corresponding to the thickness of the banknote B or the like.

The amount of displacement of the lever 14a is detected by a displacement sensor 20. The displacement sensor 20 is, for example, shown in FIG. 2 (^) (B).
As shown in FIG. 2, it can be configured by a light projector 20a and a light receiver 20b, which are placed at opposing positions with the other end 14a of the lever 14 in between. Light is always projected from the light projector 20a toward the light receiver 20b. Detection roller 1
3 is in contact with the conveyance roller 12, the projector 20
Most of the projected light a is detected by the light receiver 20b. When one bill B enters between both rollers 12 and 13,
A part of the optical path of the projected light is blocked by the other end 14a of the lever 14, and the amount of light incident on the light receiver 20b is reduced. Thicker media or double banknotes are transferred to roller 12.1
3, the amount of light incident on the light receiver 20b further decreases. In this way, a detection signal representing the thickness of the banknote B or other medium is obtained from the light receiver 20b.

FIG. 3 shows another example of a displacement sensor, in which a magnetic sensor 21 is used. Lever 14. At least the end portion 14a is made of a magnetic material or a permanent magnet. The magnetic sensor 21 outputs a signal representing the position of this end 14a.

FIG. 4 shows an outline of the electrical configuration of the banknote discriminating device. After the detection signal representing the thickness from the displacement sensor 20 or 21 is amplified by the amplifier circuit 33.

The signal is converted into a digital signal at a constant sampling period in the A/D conversion circuit 32, and is taken into the control circuit 30 via the 110 port 31. The control circuit 3o includes a CPU and a memory, and stores captured data in the memory. The data acquisition method may be a DMA transfer method.

FIG. 5 shows an example of the thickness detection signal obtained from the displacement sensor 20 or 21 when a banknote or medium passes between the rollers 2.13.

FIG. 5(A) shows a thickness detection signal when a blank sheet passes through. Level V indicates the level when no medium is present. When the blank paper enters between both rollers 2.13, the level of the detection signal decreases to the level v1a corresponding to its thickness, and while the blank paper passes through.

This level V1a is maintained. When the blank paper passes between the rollers 2.13, the level of the detection signal returns to V.

FIG. 5(B) shows changes in the detection signal when a banknote passes. While the banknote passes between both rollers 2.13, the level of the detection signal fluctuates up and down near the level of the downward bracket to a level corresponding to its thickness. This is because there are irregularities caused by printing on banknotes, which can be detected. If an upper reference level Vu and an upper reference level VL corresponding to the unevenness are set, most of the fluctuation components of the detection signal due to the unevenness will exceed the level Vu and fall below the level vL.

FIG. 5(C) shows a detection signal in the case of a counterfeit banknote such as a copy ticket created by color copying a banknote. When a counterfeit banknote passes between both rollers 2.13, the detection signal decreases at a level V or C corresponding to its thickness, but there is no fluctuation due to unevenness as in the case of a genuine banknote shown in FIG. 5(B). does not occur often.

FIG. 5(D) shows how noise is generated due to wrinkles, folds, etc. in blank paper or counterfeit banknotes. If these media have almost the same thickness as genuine banknotes, the noise component will exceed the upper reference level Vu or fall below the upper reference level VL.

The number of times that happens is very small.

To summarize the above, counterfeit banknotes such as blank paper and photocopied banknotes have few irregularities, so even if the thickness of the paper is the same as that of banknotes, as shown in Figures 5 (A) and (C), The detection signal never or almost never exceeds the upper reference level VH or falls below the upper reference level VL. However, as shown in Figure 5 (D), if the paper is wrinkled or folded, noise components will appear in the detection signal.
This goes outside the range of level v, ■, but the number is small and is I L .

On the other hand, in the case of genuine banknotes, the detection signal fluctuates due to unevenness caused by printing, and goes outside the range of levels v and vL at many locations. Therefore, it is possible to count the number of times the detection signal exceeds level V 1 and the number of times it falls below level Vt, and if these are greater than or equal to the predetermined examples A and B, respectively, it can be determined that the banknote is a genuine banknote.

An example of a bill authenticity determination algorithm performed by the CPU of the control circuit 30 based on the above concept is shown in FIG.

A detection signal from the displacement sensor 20 while the medium is passing between the rollers 12 and 13 is taken into the CPU at a predetermined sampling period and stored in the memory. The CPU determines whether there is a change in the detection signal acquired by a known method exceeding the upper reference level Vu and then returning to below this level Vn (step 41), or whether there is a change in the detection signal that goes below the upper reference level VL and then becomes equal to or higher than this level VL. It is determined whether or not there is (step 42), and the number of times is counted and stored in memory. If the number of times the banknote exceeds the level Vn is A or more (step 48) and the number of times the banknote falls below the level Vt is B or more (step 44), it is determined that the banknote is a genuine banknote. In other cases, the banknote is determined to be a counterfeit banknote.

In FIG. 5(B), when two bills are conveyed in an overlapping manner, the detection signal is at level V, as shown by the broken line.
, ■ The level LV2 is much lower than that of . Further, in the case where cellophane tape is attached to the banknote, the detection signal will be at a slightly lower level V11 at the corresponding location.

Therefore, by providing a reference level that can distinguish level v2 from other levels, it is also possible to detect two bills. Furthermore, an algorithm that detects the presence of a level component such as level "11" in a part of the detection signal can detect abnormal banknotes such as the presence of adhesive tape.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing the thickness detection mechanism, FIG. 2 is a diagram showing the arrangement of a displacement sensor, and (A) is a side view. (B) is a plan view, FIG. 3 is a side view showing the arrangement of other displacement sensors, FIG. 4 is a block diagram showing the outline of the electrical configuration of the bill discriminating device, and FIGS. 5 (A) to (D) FIG. 3 is a waveform diagram showing thickness detection signals for various media. FIG. 6 is a flow chart showing the banknote discrimination processing procedure. 20, 21...Displacement sensor. 30...control device. Patent applicant Tateishi Electric Co., Ltd. Agent Patent attorney Kenji Ushiku (1 other person) Figure 4 Figure 5 Figure 6

Claims (2)

[Claims] (1) A thickness sensor that detects the unevenness of a banknote and outputs a detection signal representing it, and a detection signal output from the thickness sensor while the banknote is being conveyed to detect the unevenness pattern of the banknote. A bill discriminating device comprising: means for determining the authenticity of a bill by obtaining data representing the bill and comparing it with a reference uneven pattern. (2) The determination means includes means for respectively detecting the number of times the detection signal exceeds a predetermined upper reference level and the number of times the detection signal falls below a predetermined lower reference level, and a predetermined value corresponding to the detected number of times. The bill discriminating device according to claim (1), which determines the authenticity of a bill using the results obtained by comparing the two.