JP2575748B2 - Paper sheet abnormality detection device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a sheet abnormality detecting device for detecting an abnormal thickness of a sheet in an apparatus for handling a sheet such as a bill.

(Technical background of worship and problems to be solved) Conventionally, the thickness of paper sheets, for example, paper sheets with abnormal thickness such as two overlapping paper sheets or paper sheets with tapes, etc. are detected. In such a case, generally, the displacement of the transporting roller or the like from a reference position is detected optically or by magnetic means. The roller gap of such a detecting device is adjusted in advance so as not to be displaced even if only one sheet is conveyed. However, such gap adjustment is not easy, and the gap is constantly adjusted. Otherwise, accurate thickness abnormality could not be detected.

Further, in order to detect the overlap of two sheets, a displacement amount is detected in accordance with the thickness thereof, and when the displacement amount exceeds a preset threshold, it is determined that the two sheets overlap. In the case of detection, it is impossible to detect when a thin tape or the like is attached to a sheet. For example, the thickness of a bill is 70 to 100 μm, and therefore, the threshold for detecting the overlap of bills is set to about 150 μm. Therefore, no abnormality can be detected for a banknote to which a tape or the like of 30 to 60 μ is stuck. This causes a problem when the banknotes are classified into genuine notes and unfit notes.

(Object of the Invention) The present invention has been made in view of the above circumstances, and an object of the present invention is to detect a defect of a sheet even when a thin tape or the like is stuck to the sheet. Another object of the present invention is to provide a paper sheet abnormality detecting device which can be rejected as a damaged paper.

(Means for Solving the Problems) The present invention relates to an abnormality detecting device for paper sheets such as banknotes, and an object of the present invention is to provide a thickness detecting means for detecting the thickness of the entire conveyed paper sheets. A thickness estimating means for estimating the thickness of the sheet based on the output of the thickness detecting means, a threshold setting means for setting a threshold based on the estimated thickness, and a detection signal of the thickness detecting means. This is achieved by providing storage means for storing, and comparison determining means for comparing the stored detection signal with the threshold to detect an abnormality in the paper sheet.

(Effects of the Invention) The present invention estimates the thickness of a sheet every time the sheet is conveyed, instead of determining the thickness of the sheet based on a fixed threshold value, and estimates the thickness. A threshold is determined by adding or multiplying a certain value to the thickness thus determined, and whether or not the detection signal exceeds the threshold, or the amount of the detection signal exceeding the threshold is determined to detect an abnormality in the sheet. I have to. In this way, a new threshold is set every time a sheet is transported, so even if an extremely thin abnormal object such as a tape is stuck on the sheet, the abnormality can be detected reliably. It is.

(Embodiment of the Invention) Fig. 1 shows a mechanical schematic structure of an abnormality detecting device according to the present invention, and a bill thickness detecting means continuously detects the thickness of a bill 1 being conveyed. The bill thickness detecting means is provided with a first transporting device 10 and a second transporting device 20, and is configured to detect a bill inserted from an insertion slot (not shown) or a bill 1 from a storage unit (not shown). , Each of which is sandwiched between a pair of upper and lower transport belt mechanisms and transported one by one in the A direction. Between the first transfer device 10 and the second transfer device 20, a pair of upper and lower detection rollers 20A,
20B is provided, and the detecting rollers 20A and 20B have a third
A bill thickness detecting mechanism showing the principle in FIGS. (A) and (B) is connected, and the bill thickness detecting mechanism detects the thickness of the bill 1 to be conveyed.

3 (A) and 3 (B) show the operating principle of the bill thickness detecting mechanism. FIG. 3 (A) shows a standby state where the bill 1 has not passed, and FIG. 3 (B) shows a bill 1 which has passed. , Respectively. In this bill thickness detection mechanism, the detection arm 3 operates on the lever principle with the shaft 6 as a fulcrum, the lower detection roller 20A is fixed in position, and the upper detection roller 2
0B is constantly pressed downward via the spring member 5 and the detection arm 3 engaged with the spring member 5. Here, as shown in FIG. 3 (B), when the bill 1 is conveyed and passes between the detection rollers 20A and 20B, the detection roller 20B is pushed upward by the thickness δ of the bill 1. Then, the lower end 31 of the detection arm 3 is also pushed up by the thickness δ via the bearing 8 connected to the shaft of the detection roller 20B, and the amount of displacement (thickness δ) of the detection arm 3 having the shaft 6 as a fulcrum is increased. It is enlarged (for example, 5 times) by the lever principle and pushes the potentiometer arm 2 via the pushing portion 32 at the upper end, so that the potentiometer arm 2 is rotated by the displacement angle θ and the rotation axis of the potentiometer is also at the same displacement angle. rotate by θ.

In the present invention, as shown in FIG. 2, the above-mentioned bill thickness detecting mechanism is divided into three parts in the conveying direction of the bill 1 and provided independently. That is, although the lower detection roller 20A is one, the upper moving detection roller 2A
0B is divided into 20B1, 20B2 and 20B3, and the detection roller 20B1
20B3 independently operate as described above. FIG. 4 shows a configuration example of the present invention, and thickness detection signals DS1 to DS3 from detection rollers 20B1 to 20B3.
Is input to the multiplexer 41, and the selected signal is
The signal is converted into a digital signal by the A / 2 converter 42 and taken into the control system of the CPU 40. A ROM 43 and a RAM 44 are connected to the CPU 40 via bus lines. The CPU 40 controls the multiplexer 41 and the A / D converter 42, and controls the transport of the transport devices 10 and 20 described above.

In such a configuration, an operation example of the present invention will be described with reference to a time chart of FIG. 5 and a flowchart of FIG.

The detection rollers 20B1 to 20B3 are disposed in a positional relationship as shown in FIG.
Tape N1 on the surface of banknote 1 in the shape and position shown in the figure
It is assumed that ~ N6 is attached. When the banknote 1 is taken into such a banknote 1 by a transport device as shown in FIG. 1 (step S1), the thickness of the banknote 1 is continuously detected by the banknote thickness detection mechanism according to the transport ( In step S2, detection signals DS1 to DS3 as shown in FIGS. 5B to 5D are output from the potentiometers engaged with the detection rollers 20B1 to 20B3, and input to the multiplexer 41. The multiplexer 41 sequentially outputs the detection signals DS1 to DS3 to the subsequent stage at the control timing of the CPU 40, converts the detection signals into digital quantities by the A / D converter 42, and then stores the digital quantities in the RAM 44. in this case,
Since the detection signals DS1 to DS3 generate noise at the leading end and the trailing end of the banknote 1 due to mechanical vibrations and the like, noise prevention measures are separately taken, and as shown in FIG. The digital amounts of the detection signals DS1 to DS3 are handled as stable data. After that, the CPU 40 estimates the thickness of the bill 1 based on the value of the region L of the detection signals DS1 to DS3 of the taken bill 1. (Step S3). This thickness estimation is based on the detection signal DS1 shown in FIGS. 5 (B) to 5 (D).
The minimum value of the signal from which the high frequency component noise signal is removed in the region L of ~ DS3 is estimated as the thickness of the banknote 1, and this thickness is set as D. Note that the minimum value may be the minimum value of all the stable data, but usually the stable data is divided for each predetermined area to obtain an average value, and the minimum value is used. Since the high frequency component often occurs due to noise due to wrinkles or the like of the bill 1 and / or inherent noise of a mechanical system and a sensor system, it is removed at a preset level. And this estimated thickness D is the average thickness of a bill, for example, 70 to
It is determined whether 100 μ is within the range of, for example, 50 to 120 μ which is set as an allowable range in advance (step S4), and if it is 50 μ or less or 120 μ or more, the bill 1 is rejected as an abnormal bill. (Step
S8).

When the estimated thickness D of the bill 1 is within a predetermined range, the bill is a normal bill, and the thickness D obtained as described above is, for example, a value α corresponding to the thickness of a tape, for example,
By adding 30 μ, (D + α) is set as the threshold TH (step S5), and the fifth threshold already stored in the RAM 44 is set.
The values are compared with the values of the detection signals DS1 to DS3 shown in FIGS. (B) to (D) (step S6). This detection data and threshold TH
If all the detection data are smaller than the threshold, no tape etc. is attached,
(Step S7), and if any data exceeds the threshold, it is rejected as an abnormal bill.
However, the example of FIG. 5 (B) shows a tape N1 having a relatively short width.
Is detected, and only a short pulse corresponding to the width of the tape N1 is output as the detection signal DS1. In such a case, the detection signal DS1 is taken as a genuine note. This is because if a short tape or the like is attached as in this example, the banknote is extremely unlikely to be illegally used. or,
In the case of FIG. 5 (C), since the signal corresponding to the tape N2 exceeds the threshold TH and the pulse width thereof is relatively wide, it is rejected as an unfit note. Further, in the example shown in FIG. 5 (D), the width of each of the tapes N3 to N6 is short, and the detection signal DS3
Is also four short pulses, but since the integrated value is relatively long, it is rejected as a damaged note.

(Modifications of the Invention) In the above-described embodiment, the bill thickness detecting mechanism is divided into three in the bill conveying direction, but the number of divisions may be one or two or more. As a method, for example, a strain gauge or a proximity sensor can be used. In the above embodiment, the threshold is the same for a plurality of banknote thickness detecting means. However, it is also possible to determine whether the banknote is correct by changing the threshold between both ends and the center, or between the front and the rear. It is. Furthermore, in the above description, the constant value α is added to the estimated thickness D, but the threshold may be estimated by multiplication or the like. Further, the estimation calculation of the thickness D is performed using the first half data at the end of the thickness detection of the first half of the bill, for example, and thereafter, the thickness detection control of the second half,
If the detection data including the first-half detection data and the threshold value calculation control unit are processed in parallel, the damage determination can be completed almost simultaneously with the end of the bill thickness detection.
Further, in the above embodiment, the gap between the upper and lower detection rollers is set to zero as shown in FIG. 5 (A), but a predetermined gap may be provided to reduce mechanical vibration noise at the front and rear ends of the bill. good.

(Effects of the Invention) As described above, according to the abnormality detecting apparatus for paper sheets such as bills of the present invention, the thickness of the paper sheets is estimated each time, and a certain value is added to the estimated thickness. Since the threshold is set in this way, it is possible to reliably detect the abnormality even with an abnormal banknote to which a relatively thin tape or the like is stuck.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a bill transport device to which the present invention can be applied, FIG. 2 is a diagram showing a schematic structure of the present invention, and FIGS. 3 (A) and (B) are used in the present invention. FIG. 4 is a block diagram showing a configuration example of the present invention, FIG. 5 is a time chart showing an operation example of the present invention, and FIG. 6 is an operation example of the present invention. It is a flowchart shown. 1… Bill notes 2… Potential arm 3… Detection arm 10,20… Transport device, 40… CPU, 41… Mux, 42… A / D converter, 43… ROM, 44 ……RAM.

Claims (2)

(57) [Claims] 1. A thickness detecting means for detecting the thickness of the whole conveyed paper sheet, a thickness estimating means for estimating the thickness of the paper sheet based on an output of the thickness detecting means, Threshold setting means for setting a threshold based on the thickness; storage means for storing a detection signal of the thickness detection means; and comparison for detecting the abnormality of the paper sheet by comparing the stored detection signal with the threshold. An apparatus for detecting an abnormality of a paper sheet, comprising: a determination unit. 2. The sheet abnormality detecting apparatus according to claim 1, wherein said thickness detecting means is divided into a plurality of sections in a direction perpendicular to the sheet conveying direction.