JPS582687A - Detector for metal piece existing in sheet paper - Google Patents

Abstract

PURPOSE:To accurately detect the presence of metal piece in a sheet paper by checking changes in resonance signals due to eddy current loss of a resonance circuit made up of one coil of a pair of coils with the generation of an ac magnetic field by the other coil thereof arranged facing each other on both sides of a sheet. CONSTITUTION:Two coils 51 and 52 are arranged facing each other on both sides of a sheet paper. An ac current is fed to the coil 51 to generate an ac magnetic field while an oscillation circuit made up of the coil 52 and a capacitor 12, connected thereto generates a resonance signal according to the ac magnetic field. When any metal piece is contained in the paper, an eddy current loss causes a change in the fixed resonance signal and clamps a certain voltage through a detection circuit 131, a dc amplifier 141 and a clamp circuit 151. This voltage is processed with a comparator 161 in which a reference voltage is set to generate a metal piece detection signal from a length detection circuit 201. The signal is outputted from an OR circuit 21 connected to a circuit similar thereto thereby enabling the detection of the metal piece existing in a sheet paper.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention detects long and thin metal pieces that are inserted into paper sheets such as checks or banknotes in advance to prevent forgery. Regarding equipment.

Recently, in order to prevent the counterfeiting of checks or banknotes, many countries have begun to use counterfeit countermeasures such as copying machines and printers by inserting long thin metal pieces into the paper during the paper manufacturing process. . However, there are no detection devices in practical use that automatically detect the authenticity of banknotes, etc., which detect the presence or absence of metal pieces as described above and use this information to determine authenticity. The present invention has been made in view of the above circumstances, and its purpose is to more reliably detect the presence or absence of metal fragments on paper sheets, and to distinguish between authenticity and falsity of paper sheets. We would like to provide an effective device for detecting metal fragments present in paper sheets.

Two embodiments of the present invention will be described below with reference to the drawings.

flL1 Figure 1ml, BLake 40 showing an example of a banknote P containing a metal piece according to the present invention, 1 is paper, 2 is this paper 1
It is a piece of metal that exists inside. For example, this metal piece 2 has a thickness of about 20 μm, a width of about 0.5 to 1, and a degree of fortune.
The length is the same as the width of paper 10.

The paper is inserted in a direction perpendicular to the longitudinal direction of the paper 1 (which is the transport direction of the banknote P).

FIG. 2-1 shows the detection head of the detection device according to the present invention and its installed state, and the above-mentioned banknote P is conveyed in the direction perpendicular to the arrow by the conveyance bell) 3. In this case, the two banknotes P are connected to the conveyor belt 3 at multiple points in the transverse direction.
... are held and transported. Therefore, the metal pieces 21 in the nine banknotes P are in a state of being present in a direction parallel to the layer in the conveying direction. In addition, 2! indicates the position of the metal piece when the banknote P is conveyed in the reverse IK direction. In the middle of the conveyor belt 3.3, on both sides (upper and lower) thereof, there is a pair of rectangular detection heads 41e4! are provided opposite to each other in the conveying direction 1 and the straight direction. This detection head 41e4m has each opposing surface serving as a sensing surface, and has an elongated annular transmitting coil 51*5 at a portion corresponding to each of these sensing surfaces. l* Receiving coil 52tS4 is buried in winding scissors.

has been done. In the case of child, each coil 51* as, J+
54 is a direction perpendicular to the conveyance direction a of the banknote P.

It is wound parallel to the surface of the banknote P being conveyed.

The coil axis is perpendicular to the surface of the banknote 10 being conveyed. However, this detection spatula is 41w42
The banknotes P are shown to be conveyed in a non-contact manner between the two.

In the detection head 41, a transmitting coil 51*151 that generates two alternating magnetic fields is connected to the detection head 4! Receive coil 5! , 5.4 is built-in. The transmitting coil 51, the receiving coil 52, and the coils 53 and 54 are arranged to face each other with a belt in between, and their positions correspond to the metal pieces 21 and 22. The length of each transmitting and receiving coil in the direction perpendicular to the conveying direction is made longer than the width of the metal piece, taking into account the skew of the paper sheet and the displacement of the conveying position.

61*62 are magnetic fields emitted from the transmitting coils 51 and 53, respectively.

FIG. 3 shows the electric circuit of the detection device in this embodiment. 111. llz is a positive Ili wave oscillator that separately supplies a sinusoidal high frequency signal to the transmission filters 51 and 51 in the one detection head 41; 121*
12z is a receiving coil 52 in the other detection head 42;
*54 and a capacitor forming a parallel resonant circuit, 13
1, 13g is a detection circuit that converts the AC signal generated across each of the capacitors 121*12g into a DC signal by envelope IIIkIIa detection; 141. 143 is a DC amplifier, 151. 15. is the clamp circuit,
161. 16.2 is a comparator, 201. 20 is a length detection circuit that measures and determines the time width of each binary signal of the comparators 161t and 16z O, 21 is an OR circuit, and 20
When an output signal is generated from either of 1°201.

A logical sum signal is output, and the final signal is a metal piece detection signal.

Next, the operation in such a configuration will be explained.

Transmitting coil B1w Receiving coil 52 A stone that explains Confucianism.

! 51 e The operation on the 54 side is exactly the same as in 51*521m, but note t' is omitted. , If the metal piece of banknote P is transported at 21@, the detection circuit 1
The output of 31 becomes the signal B shown in Figure 4 or Figure 5. In addition, Figure 5 is a waveform diagram when the metal piece was cut in the middle. This signal (B) is clamped by the clamp circuit 151.
The signal C indicates llc, and the detection signal section 19 of the metal piece 21
Otherwise, it is clamped to a constant potential. The output signal C of this clamp circuit "151" is supplied to the comparator 161, where it is compared with the reference level signal 17 to calculate the
It is converted into a 200 million signal as shown in Figure 5 of the Nine Calculation Calculations. This signal is transmitted to the length detection circuit 2 consisting of a counter etc.
0, and the one-hour width is checked, and if the length exceeds a certain regulation, an output signal E is generated as a detection signal for the metal piece 21. This signal is sent to the banknote discriminating device via the OR circuit 21 and is used for determining the authenticity of the banknote P.

With such a configuration, it is possible to automatically and reliably detect the presence or absence of the metal piece 2 inserted into one banknote P to prevent forgery. Especially the two coils.

-1) Send-S Ill! $1 (5n) and received carp y
5g (5+) are used, and these are installed on both sides of the banknote P being conveyed.For example, if only one coil K is used (II! There are fewer false positives than in case 9), and more reliable detection is possible. That is, FIG. 6 shows the output fluctuation characteristics of the detection circuit 13° (132) with respect to the positional deviation of the banknote P from the detection head 41*4m in the case of one coil described above. As is clear from this figure, in the case of one coil, the positional shift range of the banknote P is i! ! Since the output fluctuation range R of 8 Kt't is extremely large, this becomes a major cause of false detection and a reliable detection operation cannot be expected. On the other hand, the output fluctuation characteristics in the case of two coils according to the present invention are as shown in FIG. 7, and the output fluctuation range I! It can be seen that R is extremely small. without giving rise to false information.

This enables more reliable detection.

In addition, in the embodiment of 11F211, the case where the position of the metal piece that rubs the paper sheet is fixed has been explained.

If there are multiple types of paper sheets and the position of the metal piece is different depending on the type 111, the transmitting coil 51°51 is adjusted according to the position of the metal piece as shown in the calculation 5rit:to.
', 51e 53' and receiving coil! '1 e,'
, Sat Is4', and if the metal piece is located in the center of the paper industry, only the transmitter coil and the receiver coil III may be used. In addition, in FIG. 8, the metal piece 21
and 21 show the situation when one paper sheet is transported in the forward direction and the reverse direction at the position of the metal piece in one type of paper industry, and 21'
and 22' are for metal pieces of other types of paper sheets. The same purpose as in 4 can be achieved by making the transmitting coil 5 into a single coil elongated in the direction perpendicular to the conveyance direction 1 as shown in FIG.

Further, in the above embodiment, a case has been described in which a metal piece existing in a single banknote is detected, but it goes without saying that the present invention can also be applied to detecting metal pieces present in a large number of checks or other securities, for example.

As described in detail above, according to the present invention, at least 41 111 coils and a plurality of second coils are provided facing each other on both sides of the paper sheet being conveyed, and an alternating current is applied to the first coil. A capacitor is connected to the second coil to form a resonant circuit, and this resonant circuit is made to resonate at the frequency of the alternating current. is the above 1st. When passing between the second coils, the Q of the above resonant circuit is due to the eddy current loss that occurs in the metal piece.
Paper*si by configuring to detect O changes
It is possible to more reliably detect the presence or absence of metal fragments present in a bottle, and to provide an apparatus for detecting metal fragments present in a bottle paper sheet, which is effective for determining the authenticity of a paper sheet.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and are shown in Figure 1-1b).
Figure #a is a plan view and cross-sectional view showing an example of a banknote containing a metal piece, Figure IIEi-2 is a plan view and side view showing the detection head and its installation state, Figure #a is a configuration diagram of an electric circuit, and Figure #a is a configuration diagram of an electric circuit. Figures 4 (- to ") and 551+ (2) to (0) are main part signal waveform diagrams for explaining the operation. Figure 6 is an output fluctuation characteristic diagram when using one file, and Figure 7 is An output fluctuation characteristic diagram when two coils are used facing each other, FIG. 8 is a plan view showing the detection head of another embodiment and its installation state, and FIG. 9 is a diagram showing the transmitting coil of a further embodiment. It is a plan view showing P... Banknote (paper sheet) v 21121' 12 laziness, 22'... Metal piece, 3... Conveyance bell F* 41*
4t...Detection head* 51+51 e51*
5! y5ms53554z54'...Coil. 111 e li! ...Sine wave oscillator, 121
s 12g...Capacitor* 131g 13
2...Detection circuit t 1511 152...ri2y
circuit, 161. 162... Comparator, zol. 20! ...Length detection circuit. Agent Patent Attorney Nori Chika [Yuu (and 1 other person) Presentation g and 1 -)l-P ≧

Claims (1)

[Scope of Claims] (11) In a device for detecting metal pieces present in paper products being transported, the paper sheets O being transported are arranged on opposite sides of a predetermined location in a direction orthogonal to the direction of travel. at least one □first coil, ′ and at least one 〛2 coil provided in the #EI coil, means for supplying an alternating current for generating an alternating magnetic field to the #EI coil, and the second coil. and the capacitor that constitutes the resonant circuit, and the stone resonance signal in the resonant circuit due to the eddy current loss that occurs in the metal piece when the metal piece present in the sheet of paper passes between the 1st and 2nd coils. A device for detecting metal pieces present in paper sheets, characterized in that: (2) the metal pieces have an elongated shape and are parallel to the feeding direction of one paper sheet; A device for detecting metal pieces present in paper sheets according to claim 1, characterized in that the metal pieces are present in the direction □. (3) The length of the #E1 and #2 coils is The device for detecting metal pieces present in paper sheets according to claim 2, characterized in that the length of the metal pieces on the paper sheets is slightly longer than 0 p. 2. A device for detecting metal pieces present in paper sheets according to claim 1, wherein the means for supplying alternating current is an oscillator that outputs a high frequency signal of a sine wave.
□ (5) The device for detecting metal pieces present in paper sheets according to claim 1, wherein the resonant circuit is a parallel resonant circuit. (6) The means for detecting a change in the resonance signal includes a detection circuit that detects the resonance signal, a clamp circuit that clamps the output of the detection circuit to a predetermined potential, and a binarization of the output of the two-amplifier circuit. An apparatus for detecting zero metal pieces, characterized by comprising a comparator for converting into a signal and a circuit for detecting the length of the metal piece.