CN-122029459-A - Security paper detection device for forming a plurality of magnetic fields

Abstract

The present invention relates to an electromagnetic safety paper detection door for preventing leakage of safety paper, and more particularly, to a safety paper detection apparatus for detecting amorphous microfilaments inserted into safety paper. The security paper detecting apparatus according to an embodiment of the present invention includes a first antenna having a transmitting coil and a receiving coil, a second antenna spaced apart from the first antenna in parallel by a predetermined distance and having the transmitting coil and the receiving coil, a signal generating unit for supplying current to the transmitting coil provided in the first antenna and the transmitting coil provided in the second antenna, a microcontroller for controlling a current direction of the transmitting coil provided in the second antenna, and a switching device connected between the transmitting coil provided in the first antenna and the transmitting coil provided in the second antenna so as to be switched by control of the microcontroller.

Inventors

• LI MINGXIN

Assignees

• 李明信

Dates

Publication Date

20260512

Application Date

20241021

Priority Date

20231019

Claims (6)

1. 1. A security paper detection apparatus comprising: a first antenna having a transmit coil and a receive coil; a second antenna spaced apart from the first antenna in parallel by a predetermined distance and having a transmitting coil and a receiving coil; A signal generation unit for supplying a current to a transmitting coil provided in the first antenna and a transmitting coil provided in the second antenna; a microcontroller for controlling a current direction of a transmitting coil provided in the second antenna, and And a switching device connected between the transmitting coil provided in the first antenna and the transmitting coil provided in the second antenna so as to be switched by control of the microcontroller.
2. 2. The security paper detection device of claim 1, wherein the signal generation unit comprises a signal generator and a power amplifier connected to the signal generator.
3. 3. The security paper detection device according to claim 1 or 2, wherein the transmitting coil provided on the first antenna further includes a first transmitting coil branch line and a second transmitting coil branch line extending outward from the first antenna, the transmitting coil provided on the second antenna further includes a third transmitting coil branch line and a fourth transmitting coil branch line extending outward from the second antenna, and the switching means includes a plurality of switches, each of the switches being connected between one of the first transmitting coil branch line and the second transmitting coil branch line and one of the third transmitting coil branch line and the fourth transmitting coil branch line.
4. 4. A security paper detecting apparatus according to claim 3, wherein the power amplifier of the signal generating unit includes a first line and a second line connected to the transmitting coil, the switching means includes a first switch connected between the first line and the second transmitting coil branch line of the power amplifier and the third transmitting coil branch line, a second switch connected between the second line of the power amplifier and the first transmitting coil branch line and the third transmitting coil branch line, a third switch connected between the first line of the power amplifier and the second transmitting coil branch line and the fourth transmitting coil branch line, and a fourth switch connected between the second line of the power amplifier and the first transmitting coil branch line and the fourth transmitting coil branch line, and the microcontroller controls the switches such that the current direction of the transmitting coil provided in the second antenna is alternately switched.
5. 5. The safety paper detecting apparatus according to claim 4, wherein in the switching device, the second switch and the third switch form a first switch group, and the first switch and the fourth switch form a second switch group, and the first switch group and the second switch group are connected to and controlled by the microcontroller.
6. 6. The security paper detection device of claim 5, wherein an inverter is included between the microcontroller and one of the first and second switch sets.

Description

Security paper detection device for forming a plurality of magnetic fields Technical Field The present disclosure relates to an Electromagnetic (EM) security paper detection door for preventing leakage of security paper, and more particularly, to a security paper detection apparatus for detecting amorphous microfilaments inserted into security paper. In this disclosure, the term "security paper detection device" is used generically and as used herein, the term "security paper detection device" refers to a security paper detection door that senses the presence or absence of security paper when a person carrying the security paper passes through the door, thereby triggering an alarm. Background Recently, with the rapid development of enterprises, security measures for preventing leakage of company files have been designed. As such security measures for preventing leakage of company files, a file security technique using security paper has recently been developed. Such security papers refer to papers in which an amorphous alloy is inserted, which generate a signal in an alternating magnetic field that can distinguish the properties of the material. The security paper is detected by an electromagnetic sensor at the door. Specifically, when the amorphous alloy in the security paper approaches the alternating magnetic field generated by the sensor, strong Barkhausen (Barkhausen) noise is generated in the amorphous alloy due to the alternating magnetic field. By detecting the harmonic spectrum of the barkhausen noise, the presence of security paper can be identified. Such a sensor may include a transmitting coil generating an alternating magnetic field, a receiving coil detecting barkhausen noise generated in an amorphous alloy by the alternating magnetic field generated by the transmitting coil, and an electronic system controlling the alternating magnetic field generated by the transmitting coil and processing a signal received by the receiving coil. Accordingly, since the security paper containing the amorphous alloy can be detected at the door including such a sensor, leakage of the document printed on the security paper can be prevented. Fig. 2 shows a diagram of a generation process of barkhausen noise as a core principle of the security paper detection device. When an alternating sinusoidal current such as B in fig. 2 is applied to the TX antenna of fig. 1, an alternating magnetic field is formed around the TX and RX antennas. If an amorphous metal used as a security element of the security paper exists in an alternating magnetic field, a B-H curve of the amorphous metal is formed as shown in a of fig. 2. At this time, the arrangement of magnetic domains in the amorphous metal changes with the alternating magnetic field, and noise is generated as shown in C of fig. 2. This noise is called barkhausen noise. Such barkhausen noise has a spectrum having unique characteristics in the frequency domain, as shown in D of fig. 2. The spectrum with the unique characteristics is analyzed and if the spectrum matches the spectrum of the amorphous metal used as the security element, it is determined that security paper is present and an alarm is triggered. In conventional technology, U.S. patent No. 5,414,410 discloses a transmitter for generating two alternating magnetic fields by a single transmitter coil fed with a transmitter signal current, and a receiver for detecting harmonics and intermodulation signals of the alternating magnetic fields by a receiver coil generating a receiver signal current. Furthermore, U.S. patent number 5,894,270 relates to an apparatus for monitoring of electronic security elements within an investigation region, comprising a transmitting device which transmits at least one periodic magnetic field signal to a detection zone, wherein the signal causes the security element to generate a characteristic signal, a receiving device which receives the characteristic signal, and a unit which evaluates the signal received from the receiving device and generates an alarm upon determining that the security element is present. Furthermore, U.S. patent No. 5,969,611 relates to a device for monitoring of electronic security elements within an investigation region. The apparatus comprises a transmitting device which transmits a transmission signal into the investigation region, wherein the transmission signal causes the security element to transmit a characteristic signal, a receiving device which receives the characteristic signal generated by the security element by means of the transmission signal, and a unit which evaluates the characteristic signal and generates an alarm when it is determined that the security element is present. The evaluating includes removing spikes from the received signal if the received signal contains spikes. In general, the security paper detecting apparatus has a problem in that the performance of security paper detection varies greatly according to the shape of a magnetic f