JPS592073B2 - Banknote identification device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a banknote discriminating device, and in particular, it irradiates a running banknote with light, detects the transmitted light, and compares the detected amount with that of a reference banknote. The present invention relates to a device that determines whether a banknote is correct or not by comparing the detection amount (reference amount) with a detected amount (reference amount).

In recent years, automatic transaction machines for automating bank transactions have become popular.

For example, in the automatic teller machine shown in FIG. 1, one of the important functions is to determine the authenticity of banknotes inserted by a customer. Various types of devices have been proposed for determining the authenticity of banknotes, but most of them utilize optical methods.

One example is focusing on a specific part of a pattern printed on a banknote, detecting the reflectance, transmittance, color, etc. at that part, and checking whether the detected value matches the standard value. Alternatively, there is a method of checking whether the pattern when replaced with the b-run signal matches the reference pattern. As another example of a conventional discrimination device, one shown in FIG. 1a is known.

This device consists of a detection section and a signal processing section, and the detection section is composed of a housing 1, a light source 2, a reflecting mirror 3, a lens 4, a transparent partition plate 5, and a photoelectric conversion element 6. Then, the bank note a runs at a constant speed in the dark inside of the housing 1. The light generated from the light source 2 travels upward in the drawing by the reflecting mirror 3, and uniformly illuminates the bank note a in the width direction (direction perpendicular to the running direction) via the lens 4 and the slit 8. The light transmitted through the bank note a is then guided to the photoelectric conversion element 6 via the slit 9 and converted into an electrical signal. Therefore, in this configuration, when the bank note a passes through the upper part of the slit 8, the photoelectric conversion element 6 produces a distorted wave of a time function corresponding to the pattern written on the bank note. In order to recognize the entire surface of banknote a, the signal processing section shown in FIG. 1b is provided with an integrator.

That is, the electrical signal obtained by the photoelectric conversion element 6 is amplified by the amplifier 11 and then transmitted to the plurality of band filters 1.
2, 12', 12''... in parallel and divided into several specific frequency sine wave components 13, 13', 13''..., and then each leaker 12, 12', 12 ″...
are integrated during the running period by integrators 14, 14', . . . connected to the electrical quantities 15, 15', . When the banknote a completely leaves the slit 8, the switch 16
, 16'... are activated to compare the electrical quantity 18 corresponding to a normal banknote previously stored in the memory image 1T with the output of the integrator in the comparator 19, and output a judgment signal 20. being done. However, when comparing new banknotes and used banknotes with conventional discrimination methods,
Although the amount of transmitted light and the amount of reflected light of a used banknote are both lower than that of a new banknote, the respective transmittance and reflectance are not significantly different between new and used banknotes, so correct judgment cannot be made. means.

As a result, when a banknote with a pattern made by a copying machine or the like is passed through this device, the patterns of the normal and simulated banknotes are almost the same, making it difficult to accurately distinguish between the simulated banknotes. It had a difficult problem. The present invention has been made to solve the problems of conventional devices, and an object of the present invention is to provide a discriminating device that can accurately discriminate even fake banknotes made by copying machines or the like.

Hereinafter, one embodiment of the present invention will be described based on FIGS. 2 to 5.

FIG. 2 shows an automatic teller machine in which banknotes are inserted all at once, and its configuration will be described in detail in order to make it easier to understand the requests to the discriminator. In the figure, 31 is a housing, and this housing 3
1 is provided with a deposit slot 43 consisting of a rotatable cover 32 and a storage box 33, and the customer places banknotes a in a bundle in the storage box 33 while standing. It is starting to be put into use. At the rear of the storage box 33, the banknotes a... thrown in are taken one by one into a conveyance path 37 constituted by pulleys 35... and an endless annular belt 36... A take-in rotor 38 is provided for this purpose.

That is, the outer circumferential surface of the intake rotor 38 is provided with an adsorbent 38a that communicates with a vacuum source (not shown), and as the rotor 38 rotates in the counterclockwise direction indicated by the arrow, the banknotes a... are vacuum-adsorbed and sucked one by one, starting from the earliest one. Further, a detection device 39 consisting of a light projecting section 39a and a light receiving element section 39b is disposed in the middle of the conveyance path 37, and performs bill type determination, counting, and authenticity determination of the banknotes a in the conveyance path 37. Summer 0
Furthermore, the conveyance path 37 is divided into a main conveyance path 40a and a branch conveyance path 40b, and a rotatable division gate 41 driven by, for example, a rotary solenoid is provided at this branch point. In response to a signal from 39, a controller (not shown) operates to guide correct banknotes to the main transport path 40a, and guide fraudulent banknotes to a branch transport path 40b. .

In this way, the correct banknotes a fed into the main conveyance path 40a are horizontally stacked in the deposit box 42 provided at the terminal end. Note that 43 is a vertically movable back-up plate on which the bank notes a conveyed to the safe 42 are placed, and is supported at one end of a shaft 44 so as to be lowered sequentially according to the amount of bank notes a accumulated. controlled.

On the other hand, the fraudulent banknote a sent to the branch conveyance path 40b
is a return port 4 whose terminal end faces the front of the housing 31.
5, and the fraudulent banknote a is returned to the customer. Next, FIG. 3 is a diagram showing an embodiment of the configuration of the discriminating device of the present invention. In Figure 3,
51a, 51b and 51'A, 5Vb are conveyor belts,
52... are rotating rollers for driving each belt, and the bank note a is transferred to the conveyor belts 51a, 51b and 5.
It is held between Va and 5Vb and conveyed in the direction of the arrow. An illumination unit 56 constituted by an illumination light source 53, a condensing lens 54, and a transparent guide 55 functioning as a slit uniformly illuminates a predetermined area in the width direction of the banknote a being conveyed.
The light receiving unit 57 includes a diffusion plate/transparent guide plate 58, a reflection guide plate 59, and a plurality of transmitted light receivers 60, 60.
' and a reflected light receiver 60''... The light transmitted through the bank note a is transmitted to the plurality of light receivers 60, 60'.
, 60''... Here, each light receiver has a different wavelength sensitivity, and receives transmitted light and reflected light in multiple bands.When the number of light receivers is three, for example, each light reception An example of the wavelength sensitivity of the receiver is shown in Fig. 4. In Fig. 4, curve A shows the spectral sensitivity of the first receiver 60, and curves B and C indicate the spectral sensitivity of the second and third receivers 60' and 60', respectively. 60″
shows the spectral sensitivity of A photodetector having these spectral sensitivities can be easily realized by, for example, combining a silicon photodiode with a suitable colored glass filter. FIG. 5 is a diagram showing the relationship between the illumination and light receiving area and the running position of the banknote. In the figure, a is a banknote, 61 is an illumination and light receiving area, that is, the transparent guide 5 in FIG. 3a.
5. The area of the diffusion plate 58 is shown. In this figure, the banknote a is conveyed in the direction of the arrow across the illumination and light-receiving area 61, but the area 61 is set as wide as necessary so that the banknote a does not run outside the area 61. . By doing this, it is possible to eliminate the effects of misalignment and skew in the conveyance position of banknotes a. In this way,
When banknote a passes through 61 and transmitted light and reflected light are received by a plurality of light receivers, the light receiver outputs are sent to a signal processing section.

The signal processing section will be explained with reference to FIG. 3b. The electrical signals obtained by the photoreceivers 60, 60', 60''... are amplified by preamplifiers 62, 6T, 62''... to voltage signals of appropriate levels, and the signals 63, 63',
63''... These signals are then passed through an integrator 64,
64', 64'', etc. Further, 65 is a photo switch that detects the leading edge of the bank note being conveyed and generates a leading edge signal 66. This signal 66 is sent to a timing circuit 67. The circuit 67 receives this signal 66 and generates a timing signal that controls the integration timing of each integrator.The integration time is the time from when the bank note a reaches the illumination and light receiving area 61 to when it completely passes through the area. The signals integrated for a predetermined time by each integrator in this way are Vl, V2, V3, . . . .

Signals VI, V2, V3 are then applied to adder 68;
Adder 68 adds signals Vl, 2, and 3 and outputs signal Y. The divider 69 divides the signal V1 by the signal Y to obtain the signal V1, and the divider 69' divides the signal V2 by the signal Y to obtain the signal 2. In this way, the signals Vl, V2...
are obtained, these signals Vl, 2..., Y are then sent to the comparators 70, 70ζ...70? It is compared with each reference voltage set in the reference voltage setting circuits 71, 7V...71''.The reference voltage setting circuits 71, 71ζ...71''
Each reference voltage to be set is determined in advance by passing a normal bank note through the system of the present invention. After multi-banding as described above, the ratio of each band's output is calculated to prevent damage to the banknote from partial stains, general stains,
This is to eliminate the influence of changes in conveyance speed.

In other words, securities, etc., not only become partially damaged and stained during the distribution process, but also become completely dirty, and if we consider unused banknotes as a standard, those that have been used for a long time will be exposed to light throughout. The transmittance decreases to 70% to 65%.

This fact means that it is not possible to make a correct determination simply by detecting the amount of transmitted light, but this problem can be solved if the determination is made using the relative value of the multiband output as described above. Furthermore, since the signals V1 and V2 are completely independent of the transport speed, the permissible comparison limits in the comparators 70 and 70' can be minimized.

Each comparator compares the input signal and the reference signal, and if the difference between the two is within a predetermined range, it outputs a signal 6', and if it is outside the range, it outputs a signal '0'. is then led to an AND circuit 72, and if the γ-nd condition of the circuit 72 is satisfied, the output VO becomes ``1'', and the bank note to be tested is determined to be normal. The inspected banknote is determined to be abnormal.Now, regarding a certain standard banknote, the outputs of the light receiving system of the three bands are Vl, 2,
V3, and when the fluctuation rate of the transmittance of each band of any banknote is Kl, K2, and K3, respectively, ▲&&5&
′▲.

Except in special cases, almost no spectral deviation is observed even if the transmittance and reflectance vary due to overall contamination. In other words, except in special cases.

Therefore, each value above becomes as follows. however,
YO, VOl, and VO2 are values related to standard banknotes.

Therefore, since 1 and 2 are values from which fluctuation factors that occur during the distribution process have been removed, the variation in detected values is small, and a narrow tolerance range can be set, allowing highly accurate identification. In the above equation, the output Vl,2 is obtained by dividing each output by the sum Y of the three outputs V,,V2,3, so the overflow of the divider (when the numerator is larger than the denominator) is completely eliminated. Prevented. If there are no hard constraints such as divider overflow, l' = 1/3, V2
Find the output ratio using 5=2/3, etc., and calculate V,', V2'
, V3, similar effects can be obtained. As explained above, the present invention receives light from a bank note with a plurality of light receivers, and receives a signal obtained by dividing the output of each light receiver by the output of the sum of the outputs of each light receiver, and a signal from a standard banknote. Since the obtained signal is compared with the signal obtained, it is possible to reliably determine whether a banknote is correct or incorrect even if the overall light intensity of the optical system fluctuates.

[Brief explanation of drawings]

Figures 1a and b are block diagrams showing a conventional discrimination device;
The figure is a longitudinal cross-sectional view of an automatic teller machine using the device of the present invention.
Figures a and b are block diagrams of a discriminating device showing an embodiment of the present invention, Figure 4 is a spectral characteristic diagram of a plurality of light receivers used in the device of the present invention, and Figure 5 is a diagram of banknotes in the device of the present invention. FIG. 3 is a schematic plan view for explaining the relationship between the transportation state and the irradiation area.

Claims (1)

[Claims] 1. A light source that illuminates banknotes being transported, a plurality of light receivers that receive light from the banknotes that are irradiated by this light source, and amplification of the electrical signals obtained by these light receivers, respectively. a plurality of amplifiers, an adding means for adding the outputs of these amplifiers, a dividing means for dividing the output of the amplifier of each photodetector by the output of the adding means, and a signal obtained by the dividing means. A banknote discriminating device comprising a comparison means for comparing with a reference signal for a reference banknote.