A security paper detection device capable of avoiding ambient noise.

Abstract

The present invention relates to an electromagnetic type security paper detection gate for preventing the leakage of security paper, and more specifically, to a security paper detection device for detecting amorphous microwires embedded in security paper. A security paper detection device according to one embodiment of the present invention includes a magnetic field frequency variable means, a TX antenna connected to the magnetic field frequency variable means, an RX antenna positioned to correspond to the TX antenna, an amplifier connected to the RX antenna, and a signal processing means connected to the amplifier, wherein the signal processing means provides a feedback signal to the magnetic field frequency variable means and changes the multiplication (detection) frequency, and the magnetic field frequency variable means changes the magnetic field frequency based on the feedback signal provided by the signal processing means.

Description

Technical Field

[0001] The present invention relates to an electromagnetic (EM) type security paper detection gate for preventing the outflow of security paper and a handy type security detector, and more specifically, to a security paper detection device for detecting amorphous micro-wires embedded in security paper.

[0002] In the present invention, this is generally referred to as a security paper detection device. When a person holds security paper and passes through the gate, the security paper detection device includes a security paper detection gate that detects the presence or absence of the security paper and issues an alarm, and a handy type security paper detector that allows security personnel to more detailedly search for the presence or absence of the security paper of the person entering or leaving.

Background Art

[0003] It is a technology for physical security solutions to prevent the external outflow of paper documents (outputs) printed with major information that requires security. When illegal outflow of security paper output using security paper with a special alloy material built in occurs, as an output flow prevention solution that detects this and issues an alarm, since it uses the generally applied EM (Electro-magnetic) technology, there are security vulnerabilities such as the generation of electromagnetic noise from the surrounding environment and the occurrence of detection interference or detection errors due to various alloy materials used with the advancement of the technology of portable products.

[0004] As a prior art, U.S. Patent No. 5,414,410 discloses a technology related to a transmitter for generating two alternating magnetic fields through a single transmission coil to which a transmission signal current is supplied, and a receiver for detecting harmonic waves and intermodulation signals of the alternating magnetic field through a reception coil for generating a reception signal current.

[0005] Furthermore, U.S. Patent No. 5,894,270 discloses an electronic safety element monitoring device within a checkpoint, which includes a transmitting device that emits at least one periodic magnetic field signal into a detection area, the safety element generating a specific signal, a receiving device that receives the specific signal, and a technology that evaluates the signal received from the receiving device and generates an alarm if the presence of a safety element is established.

[0006] Furthermore, U.S. Patent No. 5969611 discloses a device for monitoring electronic safety elements within an inspection area. The device transmits a signal to the detection area, which causes the safety element to generate a characteristic signal. The receiving device receives the characteristic signal generated by the safety element in response to the transmit signal, evaluates the characteristic signal, and issues an alarm if the presence of the safety element is confirmed. However, if the signal received during evaluation contains a spike signal, the device discloses a technique for removing that spike signal.

[0007] However, with the aforementioned conventional technologies, if the frequency to be detected and the frequency of externally generated noise overlap, there is a high possibility that the signal to be detected and the noise will not be separated, resulting in detection errors. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] U.S. Patent No. 5414410 [Patent Document 2] U.S. Patent No. 5894270 [Patent Document 3] U.S. Patent No. 5969611 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] The present invention aims to provide a security paper detection device that can solve the problems of the prior art. More specifically, it can reduce the possibility of detection errors caused by such ambient noise by avoiding power supply noise generated around the detection gate that superimposes the detection frequency received by the receiver (RX antenna), as well as noise generated from other surrounding electronic equipment. [Means for solving the problem]

[0010] According to one embodiment of the present invention, the security paper detection device includes a magnetic field frequency variable means, a TX antenna connected to the magnetic field frequency variable means, an RX antenna positioned to correspond to the TX antenna, an amplifier connected to the RX antenna, and a signal processing means connected to the amplifier, wherein the signal processing means provides a feedback signal to the magnetic field frequency variable means to change the multiplication (detection) frequency, and the magnetic field frequency variable means changes the magnetic field frequency based on the feedback signal provided by the signal processing means. [Effects of the Invention]

[0011] According to an embodiment of the present invention, by adjusting the distribution of the frequency multiplication (detection) frequency to be separated from ambient noise, the influence of power supply noise and noise from surrounding electronic devices can be minimized, thereby minimizing detection errors in the security paper detection device. [Brief explanation of the drawing]

[0012] [Figure 1] This diagram shows the generation process of Barkhausen noise. [Figure 2] This figure shows the basic concept of a security paper detection device according to an embodiment of the present invention. [Figure 3] This figure shows the results of avoiding ambient noise according to an embodiment of the present invention. [Figure 4] This is a block diagram showing a security paper detection device according to one embodiment of the present invention. [Figure 5] This is a detailed block diagram showing a security paper detection device according to one embodiment of the present invention.

Mode for Carrying Out the Invention

[0013] A security paper detection device according to an embodiment of the present invention includes a magnetic field frequency variable means, a TX antenna connected to the magnetic field frequency variable means, an RX antenna positioned to correspond to the TX antenna, an amplifier connected to the RX antenna, and a signal processing means connected to the amplifier. The signal processing means provides a feedback signal to the magnetic field frequency variable means to change the multiplication (detection) frequency, and the magnetic field frequency variable means changes the magnetic field frequency based on the feedback signal provided from the signal processing means.

[0014] Further, the magnetic field frequency variable means includes a signal generator and a power amplifier connected to the signal generator.

[0015] Further, the signal processing means includes a filter connected to the amplifier, an AD converter connected to the filter, and digital signal processing means (DSP: Digital Signal Processing) connected to the AD converter and providing a feedback signal to the magnetic field frequency variable means.

[0016] [[ID=十七]] Further, the security paper detection device further includes an alarm means connected to the signal processing means.

Example

[0017] Hereinafter, a security paper detection device according to the present invention will be described based on the accompanying drawings. The following description describes a preferred embodiment of the present invention.

[0018] FIG. 1 is a diagram showing the generation process of Barkhausen noise, which is the core of the basic principle of the security paper detection device. When an alternating current sine wave current as shown in B of FIG. 1 is passed through the TX antenna in FIG. 2 to form an alternating magnetic field around the TX antenna and the RX antenna, when the security paper containing amorphous metal passes through the formed alternating magnetic field, a B-H curve for the amorphous metal as shown in A of FIG. 1 is formed. At this time, due to the alternating magnetic field, the magnetic domain arrangement in the amorphous metal changes along with the alternating magnetic field to generate noise as shown in C of FIG. 1, and this is called Barkhausen noise. Barkhausen noise has a frequency spectrum with unique characteristics in the frequency domain. By analyzing the frequency spectrum with these unique characteristics, if it is the same as the spectrum of the amorphous metal, it is determined that it is security paper and an alarm is issued.

[0019] However, as shown in the frequency spectrum of FIG. 3, the frequency spectrum of Barkhausen noise is shown as a multiple of the magnetic field formation frequency. At this time, by analyzing the spectrum of the multiple frequencies (f1, f2, f3 ···) excluding the magnetic field formation frequency (f0), the presence or absence of security paper, that is, the presence or absence of amorphous metal, is determined. However, as shown in the left graph of FIG. 3, when external environmental noise occurs close to the multiple frequency (f2), an error occurs during the analysis of the multiple frequencies, and an error occurs when determining the presence or absence of amorphous metal.

[0020] FIGS. 4 and 5 are a block diagram and a detailed block diagram showing a security paper detection device according to an embodiment of the present invention for solving the error that occurs during the analysis of the above-mentioned multiple frequencies.

[0021] Referring to FIGS. 4 and 5, a security paper detection device 100 according to an embodiment of the present invention includes a magnetic field frequency variable means 110, a TX antenna 120 connected to the magnetic field frequency variable means 110, a RX antenna 130 positioned to correspond to the TX antenna 120, an amplifier 140 connected to the RX antenna 130, and a signal processing means 150 connected to the amplifier 140.

[0022] Here, the magnetic field frequency variable means 110 includes a signal generator 111 that generates a magnetic field frequency and a power amplifier 112 connected to the signal generator 111, and the signal generator 111 of the magnetic field frequency variable means 110 modifies and outputs the magnetic field frequency based on a feedback signal provided from the digital signal processing means 153 of the signal processing means 150.

[0023] The signal processing means 150 includes a filter 151 connected to the amplifier 140, an AD converter 152 connected to the filter 151, and a digital signal processing means 153 connected to the AD converter 152, which provides a feedback signal to the signal generator 111 of the magnetic field frequency variable means 110 and changes the multiplication (detection) frequency. On the other hand, the digital signal processing means (DSP) 153 generally consists of a digital signal processor and a control unit that receives the processed signal and performs subsequent processing.

[0024] Furthermore, the security paper detection device 100 further includes an alarm means 160 connected to a signal processing means 150. When the signal processing means 150 detects security paper, it controls the alarm means 160 to emit an LED or an alarm sound.

[0025] When examining the operation of this configuration, in the absence of metal objects such as safety paper around the TX antenna 120 and RX antenna 130, the signal generator 111 of the magnetic field frequency variable means 110 generates a predetermined magnetic field formation frequency (f0) signal, amplifies this signal by the power amplifier 112, and inputs it to the TX antenna 120 so that an AC magnetic field is formed around the TX antenna 120 and RX antenna 130. The signal processing means 150 then passes the signal input from the RX antenna 130 by the amplifier 140 through the filter 151 for a certain bandwidth, converts it into a digital signal by the AD converter 152, and then the digital signal processing means 153 analyzes it. If the frequency of the signal input by the amplifier 140 overlaps with the multiplication (detection) frequency region, the digital signal processing means 153 determines that the frequency of external noise due to the surrounding environment overlaps with the multiplication (detection) frequency region. To resolve this, the digital signal processing means 153 provides a feedback signal to the signal generator 111 of the magnetic field frequency variable means 110 based on the analysis results.

[0026] When the signal generator 111 of the magnetic field frequency variable means 110 changes the magnetic field formation frequency (f0) to f0+a based on the feedback signal provided by the digital signal processing means 153 and inputs it to the TX antenna 120 to form a new AC magnetic field around the TX antenna 120 and the RX antenna 130, the digital signal processing means 153 of the signal processing means 150 also changes the multiplication frequency to f1+2a, f2+3a, f3+4a, etc., and then reanalyzes the new signal input from the RX antenna 130 by the amplifier 140 to determine whether the frequency of the external noise overlaps with the changed multiplication (detection) frequency range. If the frequency of the signal input by the amplifier 140 overlaps with the multiplication (detection) frequency range again, the above process is continuously repeated so that the frequency of the external noise and the multiplication (detection) frequency do not overlap.

[0027] In other words, when the magnetic field frequency variable means 110 changes the AC magnetic field formation frequency (f0) by a based on the feedback signal provided by the signal processing means 150, the signal processing means 150 must also change the range of the frequency multiplication (detection) frequency so that f1 becomes f1+2a, f2 becomes f2+3a, and f3 becomes f3+4a. The signal processing means 150 provides a feedback signal to the magnetic field frequency variable means 110 and also changes the frequency multiplication (detection) frequency accordingly.

[0028] Through the process described above, the magnetic field formation frequency (f0) is continuously changed, and as shown in the right-hand graph of Figure 3, the magnetic field formation frequency with the least noise influence is searched for and changed. In addition, the signal processing means 150 adjusts the distribution of the multiplier (detection) frequency to separate it from the ambient noise, thereby enabling the detection of security paper without being affected by ambient noise. Therefore, the security paper detection device 100 according to one embodiment of the present invention makes it easier to analyze the multiplier (detection) frequency, thereby reducing detection errors of security paper.

[0029] As explained above, the present invention is not limited to the specific preferred inventions described above, and any person with ordinary skill in the art to which the invention belongs can carry out a variety of modifications without departing from the gist of the claims, and such modifications are within the scope of the claims. [Industrial applicability]

[0030] According to an embodiment of the present invention, a safety paper detection device can be provided that reduces the possibility of detection errors caused by ambient noise, such as power supply noise and noise generated from other peripheral electronic equipment, by avoiding such noise.

Claims

1. means for changing the magnetic field frequency, A TX antenna connected to the aforementioned magnetic field frequency variable means, An RX antenna positioned to correspond to the aforementioned TX antenna, The amplifier connected to the RX antenna, The amplifier includes a signal processing means connected to the amplifier, The signal processing means provides a feedback signal to the magnetic field frequency variable means and changes the multiplication (detection) frequency. A security paper detection device characterized in that the magnetic field frequency variable means changes the magnetic field frequency based on the feedback signal provided by the signal processing means.

2. The aforementioned magnetic field frequency variable means is Signal generator, The security paper detection device according to claim 1, characterized in that it includes a power amplifier connected to the signal generator.

3. The signal processing means is A filter connected to the aforementioned amplifier, An A / D converter connected to the aforementioned filter, The security paper detection device according to claim 1 or 2, further comprising a digital signal processing means (DSP) connected to the AD converter and providing a feedback signal to the magnetic field frequency variable means.

4. The security paper detection device according to claim 3, further comprising an alarm means connected to the signal processing means.

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