JPS6172387A - Security thread detector - 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 [Technical Field of the Invention] The present invention relates to a security thread detection device for detecting a security thread for preventing counterfeiting that is pre-inserted into, for example, banknotes.

[Technical Background of the Invention and its Problems J] Recently, due to advances in single printing technology by electronic copying companies, etc.
Forgery of banknotes, checks, and securities has become very easy.Therefore, various anti-counterfeiting measures have been taken especially for banknotes. A security thread (safety wire) with gold inside is also effective in preventing counterfeiting, and the authenticity of the banknote can be determined by the presence or absence of the security thread.

Conventionally, such a security thread detection method involves irradiating a banknote with light, detecting the reflected light and transmitted light, and detecting the presence or absence of a security thread based on a combination of the detected values.

However, with this detection method, for example, if the pattern printed on the surface of the banknote is dark, it will show a reaction similar to that of a security thread, and if a security thread is simulated with paper, it will output a signal similar to that of a security thread, resulting in false detection. Invite
It was not possible to reliably detect only genuine security threads.

[Objective of the Invention 1 The present invention has been made in view of the above-mentioned circumstances, and its purpose is to eliminate the influence of printed designs on printed matter, and false detections caused by simulated security threads made of different materials. An object of the present invention is to provide a security thread detection device that can eliminate security threads and reliably detect only genuine security threads.

[Summary of the Invention] In order to achieve the above object, the present invention performs detection using the conductivity of a security thread, distinguishes between a security thread imitated by a different material and a genuine security thread, This allows only genuine security threads to be detected.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIGS. 1(a) and 1(b) show an example of a banknote P containing a security thread according to the present invention, where 1 is paper, 2
is the linear conductive security layer present in this paper 1.
It's a thread. The security thread 2 is made of a metal piece such as aluminum foil,
Its width is about 0.5 to 1.0 mm, and the length is 10 paper width.
It is the same as method 1, and is inserted in the direction perpendicular to the longitudinal direction of the paper 1.

FIG. 2 schematically shows a security thread detection device according to the present invention. In other words, the aforementioned banknote P
is conveyed in the longitudinal direction in the direction of arrow a in the figure by an lfa conveyor belt (not shown) or the like. Therefore, banknote P
The security thread 2 within is in a state perpendicular to the transport direction a. Banknotes P transported in this way
On the upper side, a ring-shaped oscillation coil 3 that generates a high-frequency electromagnetic field is arranged, and on the lower side, an oscillation coil 3 is arranged.
An annular receiving coil 4 that generates an induced voltage by an electromagnetic field from the coil 3 is arranged opposite to the oscillating coil 3. The oscillation coil 3 is connected to an oscillation circuit 5 that generates a high frequency signal, and generates an electromagnetic field by being driven by the high frequency signal. Further, the receiving coil 4 is connected to a detection circuit 6, and the output of the detection circuit 6 is sent to a gate circuit 7 via an amplifier 7. The gate circuit 7 is configured to send only signals within the detection range to the determination circuit 10 based on a detection gate signal for setting the detection range of the banknote P output from the timing generation circuit 9. However, now, when the banknote P is conveyed in the direction of the arrow a and the security thread 2 reaches the part, the induced voltage generated from the receiving coil 4 causes eddy current loss of the mutual coils,
It is attenuated due to the resonance shift and the change in the mutual induction coefficient, and the security thread 2 is extracted as a peak voltage by the detection circuit 6. The output of this detection circuit 6 is amplified by an amplifier 7, and then passed through a gate circuit 8 to make a decision 11.
The signal is sent to the circuit 10, where the presence or absence of the security thread 2 and its authenticity are determined, and the determination result is output.

In order to make the explanation easier to understand, the oscillating coil 3 and the receiving coil 4 are shown in the drawing as long bars in the direction perpendicular to the feeding direction a, but in reality, the banknote P is drawn in the longitudinal direction. Since both ends of the banknote are held between conveyor belts and conveyed, in order to avoid the conveyor belt, the banknote is formed into a circular ring coil with an outer diameter of about 10#1, for example, and a part of the banknote P (the The security thread is detected for the central part).

Of course, the shape is limited to circular, and may be round, oval, etc.

FIG. 3 shows the timing generating circuit 9 in detail. For example, when a bill P is detected t! It is composed of a memory 11 such as ROfvl in which data indicating the range is stored, a pulse generation circuit 12 that generates pulses of a constant period, and a gate signal generation circuit 13. That is, the gate signal r'
The generating circuit 13 starts operating as soon as a detector (not shown) detects the leading edge of the banknote P, and by counting pulses from the pulse generating circuit 12,
By specifying the address of the memory 11 according to ilJ and reading f-t in the memory 11, a detection gate signal is generated to set the detection range as shown in Fig. 4, and the detection is performed. The gate signal is sent to the gate circuit 8. Thereby, the gate circuit 8 allows the output signal of the amplifier 7 to pass through and sends it to the determination circuit 10 only when the detection gate signal is a "1" signal.

Next, the determination circuit 10 will be explained in detail using FIGS. 5 and 6. FIG. 5 shows an operating principle diagram using peak voltage values of a simulated security thread and a genuine security thread. In the figure, S+, 32
is the peak voltage of the security thread Ill!
, S3 indicates the peak voltage value of the genuine security thread, VL indicates the lower limit comparison voltage value, and VH indicates the upper limit comparison voltage value. This is due to the change in induced voltage as the security thread 2 passes over the receiver coil 4, causing the security thread 2 to be represented as a peak voltage value. Generally, the peak voltage value of the security thread contained in a banknote differs depending on its material, but since security threads made of the same material are constant, the upper and lower limit comparison voltage values VH.

By comparing with the VL, genuine security threads and simulated security threads can be distinguished. FIG. 6 shows a specific example of the determination circuit 10 based on such an operating principle.

That is, the output of the amplifier 7 (the peak voltage of the security thread iI'tj
) are supplied to a comparator circuit 21.22, where each comparison voltage value V of the upper limit and lower limit from the comparison ``pressure setting circuit 23.24''
It is compared with H and VL, and each comparison result is sent to the discrimination circuit 25. Based on the comparison results of the comparison circuits 21 and 22, the determination circuit 25 determines that the security thread is a depreciable security thread when [V + - ≦Peak voltage of the security thread 1 direct ≦V1 (]), and performs the security thread.・If the configuration is 1゜, which outputs the number 1 indicating that there is a thread, and otherwise identifies it as a mock IR security thread and outputs a signal indicating that there is no security thread. Since the detection is performed using the conductivity of the security thread 2, there is no influence from the printed design of the banknote P, and it is possible to distinguish between the imitation security thread and the genuine security thread. can be reliably detected.

Furthermore, since the detection range of the security thread 2 is set for the banknote P and the security thread 2 is detected within the detection range, the authenticity of the security thread can be determined based on the position of the security thread. becomes possible.

FIG. 7 shows another embodiment of the determination circuit 10.

Note that the same parts as in FIG. 6 are given the same reference numerals, and the explanation thereof will be omitted, and only the different parts will be explained. This embodiment counts the number of security threads attached to one bill, compares it with a preset standard value, and determines that it is a genuine security thread when it is equal to the standard value by 4. It outputs a signal indicating that there is a security thread, and determines that the others are simulated security threads, and outputs a signal indicating that there is no security thread. In addition, in FIG. 7, by sending the security thread presence signal output from the discrimination circuit 25 to the integration circuit 2G, the security thread presence signal is accumulated until one bill P passes.) (Karan 1-) Do it. Then, when the bill P has passed, the integrating circuit 2
The product ki'J of 6 is compared with the reference value from the reference value setting circuit 28, and when the two are equal, outputs 13H indicating that there is a security thread, and otherwise outputs a signal indicating that there is no security thread. It is. According to this embodiment, detection of genuine security threads becomes even more reliable, especially when several security thread signals can be obtained from one banknote due to substances used in counterfeit banknotes. This is effective in preventing erroneous judgments when

FIG. 8 shows still another embodiment of the determination circuit 10. This embodiment detects the width of the security thread and compares it with a preset value,
This is to determine the authenticity of the security thread.

That is, in FIG. 8, the output of the amplifier 7 sent via the goo 1-circuit 8 is supplied to the comparison circuit 31, where it is compared with the comparison voltage value VR from the comparison voltage setting circuit 32 to obtain a binary value. Create a signal. FIG. 9(a) shows an example of the output signal of the amplifier 7, and FIG. 9(b) shows an example of the binary signal obtained by converting the signal into a binary value. This binarized signal is sent to a change detection and comparison circuit 33, where the signal width t1 is converted into a constant cycle pulse. The converted pulses are sent to the pulse integration circuit 34, where they are integrated (counted). Then, in comparison circuits 35 and 36, the integrated value of pulse integration circuit 34 is compared with the upper and lower limit reference values from reference value setting circuits 37 and 38, and the comparison results are sent to three discrimination circuits. . The three determination circuits determine that the security thread is genuine when [lower limit reference value ≦pulse accumulation value ≦ upper limit reference value] based on the comparison results of the comparison circuits 35 and 36, and determine whether there is a security thread. Outputs a signal, otherwise outputs a signal without a security thread.

In other words, if the pulse vi calculation value (width of the security thread) is less than the lower limit base IW value, it is determined that there is no security thread, and if the upper limit base value J stiffness is also large, it is determined that it is a simulated security thread. It outputs a signal without a security thread. According to this embodiment, a genuine security thread can be detected more reliably, and is particularly effective in preventing misjudgment of a simulated security thread whose shape has been deformed.

In the above embodiments, a case has been described in which a security thread inserted in a banknote is detected, but the present invention is not limited to this, and the present invention is not limited to this. It can also be applied to detecting security threads that are encased in

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to eliminate false detections caused by simulated security threads (caused by the influence of printed patterns on printed matter and different materials), and detect only genuine security threads. A security thread detection device capable of reliable detection can be provided.

[Brief explanation of the drawing]

1 to 6 are for explaining one embodiment of the present invention. FIG. 1 is a plan view and side sectional view showing an example of a banknote with a security thread, and FIG. FIG. 3 is a schematic diagram showing the thread detection device;
The figure is a block diagram showing the timing generation circuit in detail.
The figure shows an example of the detection gate signal for the detection range of banknotes, FIG. 5 is a diagram for explaining the operating principle of the determination circuit, FIG. 6 is a block diagram showing a specific example of the determination circuit, and FIG. 8 is a block diagram showing an embodiment of the determination circuit, FIG. 8 is a block diagram showing still another embodiment of the determination circuit, and FIG. 9 is a main signal waveform diagram for explaining the operation of FIG. 8. be.・J p...Banknotes (printed matter), 2...Security thread, 3...Oscillation coil, 4...
Receiving coil, 5... Oscillation circuit, 6... Detection circuit, 1
0... Judgment circuit, 21° 22... Comparison circuit, 23.
24... Comparison voltage setting circuit, 25... Discrimination circuit, 2
6...V4 circuit, 27...Comparison circuit, 28...
Reference value setting circuit, 31... Comparison circuit, 32... Comparison voltage setting circuit, 33... Change detection comparison circuit, 34.
...Pulse integration circuit, 35.36...Comparison circuit, 37
．． 38...Reference value setting circuit, 39...Discrimination circuit.

Claims (8)

[Claims] (1) In a device for detecting a conductive security thread present in a printed matter being conveyed, a magnetic flux generating means and a magnetic flux receiving means are arranged facing each other with the conveyed printed matter interposed therebetween, and the magnetic flux receiving means 1. A security thread detection device comprising determining means for determining the presence or absence and authenticity of a security thread based on an output signal from the means. (2) The magnetic flux generating means includes an oscillation circuit that generates a high-frequency signal, and an oscillation coil that is driven by the output of this oscillation circuit and generates an electromagnetic field, and the magnetic flux receiving means includes an electromagnetic field generated from the oscillation coil. 2. The security thread detection device according to claim 1, comprising a receiving coil that generates an induced voltage by a field, and a detection circuit that detects the output of the receiving coil. (3) The determination means includes a first comparison means for detecting a change in the output of the magnetic flux receiving means that is larger than a first level set in advance, and an output of the magnetic flux receiving means that is smaller than a second level set in advance. A patent characterized in that it is comprised of a second comparing means for detecting a change, and a determining means for combining the comparison results of the first and second comparing means to determine the presence or absence of a security thread and whether it is genuine or false. A security thread detection device according to claim 1 or 2. (4) The determining means includes a detecting means for detecting a security thread based on a change in the output of the magnetic flux receiving means, an integrating means for integrating the output of the detecting means, and an integrated value of the integrating means and a reference value set in advance. and determining means for determining the authenticity of the security thread by comparing the security thread with the security thread.
3. The security thread detection device according to item 1 or 2. (5) The security thread detection device according to claim 4, wherein the reference value is the number of security threads existing in an authentic printed matter. (6) The determination means includes means for detecting a change in the output of the magnetic flux receiving means that is larger than a predetermined level and converting it into a pulse signal, and a pulse integration means for integrating the pulse signals output from the means; Claim 1, characterized in that it is comprised of a determining means for determining the authenticity of the security thread by comparing the integrated value of the pulse integrating means with upper and lower limit values set in advance. or the security described in paragraph 2.
Thread detection device. (7) The security thread detection device according to claim 6, wherein the upper limit value and the lower limit value are values corresponding to the width of the security thread existing in an authentic printed matter. (8) The security thread detection device according to claim 1, wherein the printed matter is a banknote.