JPS63267638A - Duplication detecting device for printed fixed form paper sheet - Google Patents

Abstract

PURPOSE:To accurately duplication of paper sheets always, even in case of existence of any unprinted portion on the paper sheets, by measuring transmitted light quantities at the plural positions of the paper sheets and comparing them with a standard value and judging it as duplication when duplication is detected even at one place. CONSTITUTION:A thickness detector 1 is provided to each of three places where the paper sheets are passed through an the thickness of an unprinted portion is detected by at least one thickness detector 1. On the other hand, a constant K is provided in a presetting device 4 in order to judge any duplication of paper money and is given to a comparing device 3. Thereat, an output signal S of each signal processing circuit 2 is compared with a judging constant K, and it is judged whether the signal S is smaller than the constant K. When the output signal S of at least one thickness detector 1 is smaller than the constant K, it is judged that two or more pieces of the paper money are overlapped. Therefore, overlapping can be surely detected, even though there are some unprinted portions (a water-mark) on the paper sheets.

Description

[Detailed Description of the Invention] Summary of the Invention The amount of transmitted light at multiple locations on paper sheets is measured, and these Jll
The presence or absence of overlap is determined by comparing the l constant value with a predetermined reference value, and when it is determined that there is at least one overlap, an overlap detection output is generated. It is now possible to accurately detect overlaps even when there are unprinted parts (for example, watermarks) on paper sheets.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting overlapping of printed regular paper sheets, such as an automatic cash dispensing machine.

The present invention relates to a device for detecting overlapping (for example, detecting two) banknotes being conveyed in a deposit dispensing machine, automatic currency exchange machine, or the like.

Conventional technology and its problems Conventional devices for detecting overlapping paper sheets include two types: one that measures the amount of light transmitted through the paper sheets and compares it with a predetermined reference value; There were some cases where the thickness was determined to be 71FJ by sandwiching leaves.

Methods that use the amount of transmitted light measure the amount of transmitted light using a single light source, so when paper sheets have unprinted parts, such as watermarks on banknotes, it is difficult to measure the printed parts. 1
The amount of light transmitted through the sheet and the amount of light transmitted through the watermark portion that overlapped with each other were sometimes about the same value, and the reliability was not high. Also,
When measuring the thickness of paper sheets using a roller, it is necessary to improve the Ap1 accuracy because it detects the difference between the thickness of one sheet and two sheets, which causes an increase in cost. In addition, there was a problem in that measurement accuracy changed due to aging.

Summary of the Invention Purpose of the Invention The purpose of the present invention is to provide an overlap detection device for paper sheets that can accurately detect the overlap even if the unprinted parts of two sheets overlap, such as watermarks on banknotes. It is in.

Structure and Effects of the Invention The present invention comprises a light source, and a light receiver that faces the light source and receives light projected from the light source across the passing position of the paper sheet. a plurality of thickness detectors arranged to detect the thickness of the spot;
In addition, the values indicated by the output signals of the respective thickness detectors are compared with a reference value for determining overlapping of paper sheets, and the overlap is determined based on the output signal of at least one thickness detector. The present invention is characterized in that it includes means for outputting an overlap detection signal when an overlap occurs.

In the thickness detector mentioned above, it is preferable that the light source projects two types of light having different wavelengths, and that the light receiver receives the two types of light separately.

In this case, first calculation means for calculating the logarithms of the values indicated by the light reception signals of the two types of light.

By providing a second calculation means for calculating the difference between these calculation results, a signal representing the thickness of the sheet can be obtained from the second calculation means.

As described above, according to the present invention, the amount of transmitted light at a plurality of locations on the paper sheet is measured and compared with a predetermined reference value, and if overlap is detected at at least one location, it is determined that the paper is facing east. Even if there are parts of the paper that are not printed,
For example, even if there is a watermark on a banknote, since the thickness is measured based on the amount of transmitted light in areas other than this area, it is possible to always accurately detect overlapping.

DESCRIPTION OF EMBODIMENTS An embodiment in which the present invention is applied to overlapping detection of banknotes, so-called two-bill detection will be described below.

An example of the configuration of a banknote overlap detection device is shown in FIG. Three banknote thickness detectors 1 are arranged in the width direction of the banknote B conveyance path. One is located at the center in the width direction of the conveyance path, and the other two are located on both sides. Each thickness detector 1 is a light receiving device that receives light projected from adjacent light sources L and R2, each having a different emission wavelength, and facing each other across the conveyance path. It consists of vessels R and R2. The output signals (2) from the light receivers R and R2 of the thickness detector 1 are sent to the sensor signal processing circuit 2, where arithmetic processing to be described later is performed, and a signal S representing the thickness t of the two banknotes B is output. These signals S are input to a comparator 3. A constant k is set in the setting device 4 to determine whether banknotes overlap, and this constant k is provided to the comparator 3. The comparator 3 compares the magnitude of the input signal S with this constant and determines whether two or more sheets overlap by ORing the comparison results.

The principle of thickness detection by the thickness detector 1 and processing circuit 2 is as follows.

The amount of light projected from the light source is I (λ is the wave 0, λ ) The amount of light that passes through one banknote B is .

If the absorption rate of light in banknote B is αyu, then the transmitted light 1i
T! is a function of the thickness t of the banknote B (it is also a function of αλ if the absorption coefficient αλ differs depending on the location), and is generally expressed as follows.

I-I exp(-a ・t)
=ll)λ 0 λ λ
In the thickness detector 1, two light sources with different wavelengths are used.
L2 h (used. These light sources Ll, L2
are an infrared wavelength light source and a green wavelength light source, respectively. λ is the infrared wavelength and λ is the green wavelength. and the first (1st
) Taking the ratio of the formula, we get the following.

λ1? λG −IoλReXI)(−αλR” t)/I o λG
eXp(U't)λG-11/I) 0λROλG exp (αλG-αλR)11t...(2)
If we take the logarithm of equation (2) and let it be S, we get the following.

S-j? n (1/I) λRλG /I) "f!n" OAR02G + (αλG - αλR)・t ...(3)th (3)
The first term in the equation is the light source, and the light amount of L2 /I') is determined accordingly, so j! n(IoλROλG constant”
If it is OAR02G, it becomes 0. Therefore, the formula (3) is S-(α,GYR)・t...(4)-
It is expressed as α. Absorption rate α, 6 R is a constant value,
If α exists, the value S becomes a linear expression of the thickness t. Therefore, this value S can be used to detect overlapping banknotes.

By the way, equation (3) is 5-1n (1) −, en (I) = 4
5) It can also be expressed as λRλG.

The transmitted light fiI,I is λRλG of the receivers R, R
12 outputs, the value S can be found by taking their logarithm and then taking the difference.

The signal processing circuit 2 performs this processing.

FIG. 2 shows a specific circuit configuration of the signal processing circuit 2. As shown in FIG. The signals output from the photoreceivers R and R and representing 1, I, and I, respectively, have the logarithm λR.
λG is input to the amplifier 5 and its logarithm J2n(I).

λR An output signal representing Jn(I) is obtained. This λG These output signals are then applied to a differential amplifier 6.

A signal representing the value S expressed by equation (5) (also referred to as signal S) is output.

In the explanation of equation (4), the light absorption rate α of banknote B
□、α、. is considered constant, the value of signal S is equal to banknote B
As described above, it is possible to detect overlapping bills (detecting two bills) by comparing the magnitude of the signal S with a certain threshold level. However, the value (αλG−αλR) varies from banknote to banknote, especially from place to place. Banknotes generally have an unprinted watermarked area, and the above-mentioned absorption rate is extremely small in this watermarked area. For this reason, the value of the signal S obtained when the watermarked portions of two banknotes overlap may fall within the distribution range of the values of the signal S for one banknote.

In order to be able to reliably detect two bills even if the watermarked portions of the bills overlap, three thickness detectors 1 are used in FIG. 1, and these are arranged in the center and on the left and right as described above. This is due to the following reason.

The position of the watermark on a bill is generally at the edge (for example, a 5,000 yen bill) or the center (for example, a 10,000 yen bill).

FIG. 3(a) shows a watermark at the end (this is called an end watermark). When there is a watermark on one edge of a banknote, even if the banknote is turned upside down or upside down, the watermark will end up on the left or right side as shown in Figure 3(a). It turns out. When the watermark is in the center of the banknote (this is called a central watermark), the watermark will be located in the center of the banknote as shown in Figure 3(b) no matter what position the banknote is in. Become. therefore,
There are six types of combinations of positions that occur when these two banknotes overlap, as shown in FIG. 3(C). If the thickness detectors 1 are arranged at three locations: the center, the left, and the right, at least one of the thickness detectors 1 will detect a portion of the banknote that has no watermark.

FIG. 4 shows the distribution of the output signal S of the signal processing circuit. The graph for the one-sheet area is obtained when one banknote B is conveyed and passed through the thickness detection position, and the graph for the two-sheet area is obtained when two banknotes are passed. Also,
The broken line shows the case where the thickness detector is placed without considering the position of the watermark, and the solid line shows the case where the thickness detector is placed at a position where no watermark is detected. Both graphs show the distribution of the signal S obtained when a large number of banknotes are passed through.

If the thickness detector is arranged without considering the position of the watermark, the projected light of the thickness detector may transmit through the watermark, which may increase the amount of transmitted light and increase the value of the signal S.

Therefore, even if there are two overlapping banknotes, the distribution of the signal S will fall within the range of the distribution of the signal S obtained for a single banknote, as shown by the broken line.

If the projected light does not pass through the watermark, the signal distribution for one banknote and the signal distribution for two overlapping banknotes are clearly separated, as shown by the solid line. Therefore, if the above-mentioned threshold level, that is, the discriminant constant k is set at this separated intermediate point.

By comparing the signal S with this constant, it is possible to determine whether the bill is one bill or two or more bills.

In FIG. 1, the thickness detectors 1 are arranged at three locations as described above, and at least one thickness detector 1 detects the thickness of a portion without a watermark. Therefore, the output signal S of each signal processing circuit 2 is compared with a discrimination constant to determine whether the signal S is smaller than the constant. 2 if the output signal S of at least one thickness detector 1 is smaller than a constant
Determine that more than one banknote overlaps (overlap detection)
. This is the operation of comparator 3.

It goes without saying that the processing in the signal processing circuit 2 and the comparator 3 may be performed by a microprocessor or the like.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the invention. FIG. 2 is a block diagram showing the specific configuration of the sensor signal processing circuit, and FIGS. 4
The figure is a graph showing the distribution of output signals. 1... Thickness detector. 2...Sensor signal processing circuit. 3... Comparator. 5... Logarithmic amplifier. 6...Differential amplifier. Ll, L2...Light source. Rt, R2... Light receiver. B...Banknotes. that's all

Claims (3)

[Claims] (1) Consists of a light source and a receiver that faces the light source across the passing position of the paper sheet and receives the light projected from the light source, and detects the thickness of at least two different widthwise points of the passing paper sheet. A plurality of thickness detectors arranged to An overlap detection device for printed regular paper sheets, comprising: means for outputting an overlap detection signal when it is determined that there is an overlap based on the output signal of a thickness detector. (2) The printed device according to claim (1), wherein the light source projects two types of light having different wavelengths, and the light receiver separately receives the two types of light. An overlapping detection device for standard-sized paper sheets. (3) Claim 1, which comprises first calculation means for calculating the logarithms of the values indicated by the light reception signals of the two types of light, and second calculation means for calculating the difference between these calculation results. The overlapping detection device for printed regular-sized paper sheets according to item (2).