WO2020052285A1

WO2020052285A1 - Radio frequency identification circuit and contact-less ic card anti-theft device

Info

Publication number: WO2020052285A1
Application number: PCT/CN2019/090042
Authority: WO
Inventors: 李文昌
Original assignee: 李文昌
Priority date: 2018-09-10
Filing date: 2019-06-05
Publication date: 2020-03-19
Also published as: CN109325577A

Abstract

The present invention relates to the technical field of smart card theft prevention, relating in particular to a radio frequency identification circuit and a contact-less IC card anti-theft device; the radio frequency identification circuit comprises a radio frequency signal receiving unit that is used to receive a radio frequency read signal of an NFC read device and convert same into a sensing current, a rectification unit used for half-wave rectification and an interference signal producing unit used to produce and emit a radio frequency interference signal. The radio frequency identification circuit of the present invention has a simple structure and is low-cost; and a contact-less IC card anti-theft device composed of the described radio frequency identification circuit may effectively prevent criminals from stealing information within a card by means of an NFC read device when the contact-less IC card is not being used.

Description

Radio frequency identification circuit and non-contact IC card anti-theft device

Technical field

The invention relates to the technical field of smart card anti-theft, in particular to a radio frequency identification circuit and a non-contact IC card anti-theft device.

Background technique

Since its introduction, contactless IC cards have penetrated into various areas of daily life and are widely used in various fields such as personal identification, ticketing, access control, and item identification. People's ID cards, bank cards, passports, etc. have been magnetic stripe cards. Gradually replaced with non-contact IC cards.

Contactless IC card technology widely uses digital modulation technologies such as ASK, FSK and PSK modulation. These several modulation methods are existing mature modulation technologies and are widely used in various communication systems. Amplitude Shift Keying (ASK for short) is to take different values according to the modulation of digital amplitude of the carrier wave, for example, corresponding to binary 0, the carrier amplitude is 0; corresponding to binary 1, the carrier amplitude is 1. The AM technique is simple to implement, but it is susceptible to gain changes. Frequency shift keying (Frequency Shift Keying, referred to as FSK) is to modulate the frequency of a carrier wave according to the value of digital data (such as 0 or 1). For example, the frequency of the carrier signal corresponding to binary 0 is F1, and the frequency of the carrier signal corresponding to binary 1 is F2. This technology has good anti-interference performance, but occupies a large bandwidth. Phase shift keying (PhaseShift Keying, PSK for short) is to modulate the carrier phase according to the value of digital data. For example, 180 is used to indicate a phase shift of 1, and 0 is used to indicate a 0 phase shift. This modulation technology has the best anti-interference performance, and the phase change can also be used as timing information to synchronize the clocks of the transmitter and receiver, and double the transmission rate. Among them, the ISO / IEC14443 standard A system uses a modified Miller coding method and uses 100% ASK modulation to send signals.

Because the encoding method and modulation method are publicized by the standard, many criminals steal the IC card information of others through NFC reading devices. For example, on a crowded bus, in a crowd of people, shopping places, etc., the criminals will The NFC reading device is close to the victim's non-contact IC card type ID card, bank card, passport, etc. The NFC reading device can easily clone the information in the victim's IC card, causing the victim's personal information to leak, Bank card information leaks, etc. The criminals copied the stolen IC card information into a new IC bank card, IC ID card, etc., and used the copied IC bank card to steal the victim's money or use the stolen information to perform other illegal activities and give the stolen The winner brings different degrees of loss.

Hackers or other criminals use NFC devices to steal ICs or obtain contactless IC card information of other people. The principle is as follows: NFC readers send specific RF signals to be determined, and contactless IC cards receive specific RF read signals. After responding, and transmitting its own data through the predetermined frequency, the NFC reading device receives the feedback signal of the non-contact IC card and analyzes it to obtain the information stored in the non-contact IC card, and finally realizes the non-contact type Theft of IC card information.

Summary of the Invention

In view of the shortcomings of the prior art, the present invention provides a radio frequency identification circuit and a non-contact IC card anti-theft device, which prevents the problem that the NFC device in the prior art steals the information of the contact IC card. The specific solution is as follows: :

In a first aspect, the present invention provides a radio frequency identification circuit, including:

A radio frequency signal receiving unit, configured to receive a radio frequency reading signal of an NFC reading device, and convert the radio frequency reading signal into an induced current;

A rectifying unit for performing half-wave rectification on the converted induction current;

The interference signal generating unit supplies power to the oscillation circuit according to the rectified current to generate a radio frequency interference signal, and sends the radio frequency interference signal out;

The radio frequency signal receiving unit includes a first induction coil (L1);

The rectifying unit includes a first diode (D1), a positive electrode of the first diode (D1) is connected to an output terminal of the radio frequency signal receiving unit, and a negative electrode is connected to an input terminal of the interference signal generating unit. connection;

The interference signal generating unit includes a first crystal (X1), a first transistor (Q1), a first resistor (R1), a first capacitor (C1), and a second induction coil (L2). The first resistor (R1) and the first crystal (X1) constitute a parallel circuit. One end of the parallel circuit is electrically connected to the base of the first transistor (Q1), and the other end is electrically connected to the first transistor (Q1). The collector of a triode (Q1) is electrically connected, and at the same time is electrically connected to the second inductor (L2) and the first capacitor (C1), the emitter of the first transistor (Q1) Ground.

Preferably, it further comprises a transmitting unit connected in series to the radio frequency signal receiving unit and the interference signal generating unit.

Preferably, the radio frequency signal transmitting unit includes a second induction coil (L2), and a parallel circuit composed of the second induction coil (L2) and the first capacitor (C1) converts the interference signal generating unit Emitted through the antenna.

In a second aspect, the present invention provides a non-contact IC card anti-theft device, including the above-mentioned radio frequency identification circuit.

Beneficial effect: The radio frequency identification circuit of the present invention has a simple structure and low implementation cost. The non-contact IC card anti-theft device composed of the radio frequency identification circuit can effectively prevent a non-contact IC card from being read by an illegal element through NFC when not in use Steal information from the card.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to explain the technical solutions in the embodiments of the present invention more clearly, the drawings used in the description of the embodiments are briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. The embodiments in the drawings do not constitute any limitation to the present invention. For those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a principle block diagram of an embodiment of a radio frequency identification circuit of a non-contact IC card immobilizer according to the present invention.

FIG. 2 is a circuit schematic diagram of a first embodiment of a radio frequency identification circuit of a non-contact IC card immobilizer according to the present invention.

3 is a schematic circuit diagram of a second embodiment of a radio frequency identification circuit of a non-contact IC card immobilizer according to the present invention.

4 is a schematic diagram of an embodiment of a non-contact IC card immobilizer according to the present invention.

detailed description

The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. This is a preferred embodiment of the present invention. It should be understood that the described embodiments are only a part of the embodiments of the present invention, but not all the embodiments; it should be noted that, in the case of no conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. . Based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example one

An embodiment of the present invention provides a radio frequency identification circuit. As shown in FIG. 1, the IC card anti-theft device radio frequency identification circuit embodiment principle block diagram may specifically include the following modules: a radio frequency signal receiving unit, a rectification unit, an oscillation circuit, and an interference signal. Generate unit. The radio frequency signal receiving unit is configured to receive the radio frequency reading signal of the NFC reading device and convert the radio frequency reading signal into an induced current; the rectification unit performs half-wave rectification on the induced current obtained by the conversion; The rectified voltage powers the oscillating unit to generate an interference signal. The interference signal transmitting unit sends the interference signal to the free space through the L-C capacitive-inductive parallel oscillation according to the interference signal generated by the oscillating circuit; the interference signal generating unit supplies power to the oscillation according to the rectified current. The circuit generates a radio frequency interference signal and sends the radio frequency interference signal out.

The circuit schematic diagram of the embodiment of the radio frequency identification circuit of the non-contact IC card immobilizer shown in FIG. 2, the radio frequency signal receiving unit includes a first induction coil (L1); the interference signal transmitting unit is based on the interference generated by the oscillating circuit. The signal is sent to free space through a parallel oscillation formed by the second inductor (L2) and the first capacitor (C1).

In this embodiment, the rectifying unit includes a first diode (D1), the positive pole of the first diode (D1) is connected to the output terminal of the radio frequency signal receiving unit, and the negative pole is connected to the interference Input terminal connection of signal generating unit

In this embodiment, the interference signal generating unit includes a first crystal (X1), a first transistor (Q1), a first resistor (R1), a first capacitor (C1), and a second An induction coil (L2), the first resistor (R1) and a first crystal (X1) form a parallel circuit, and one end of the parallel circuit is electrically connected to the base of the first transistor (Q1), The other end is electrically connected to the collector of the first transistor (Q1), and is also electrically connected to the second inductor (L2) and the first capacitor (C1), and the first transistor The emitter of (Q1) is grounded.

In an optional embodiment, the radio frequency identification circuit further includes a transmitting unit connected in series to the radio frequency signal receiving unit and the interference signal generating unit.

In another optional embodiment, the radio frequency signal transmitting unit includes a second induction coil (L2), and a parallel circuit formed by the second induction coil (L2) and the first capacitor (C1) will The interference signal generating unit is transmitted through an antenna.

As shown in Figure 4, when the contactless IC card is not in use, the anti-theft device of the contactless IC card is set close to the contactless IC card. When the NFC reading device is close to the contactless IC card, it transmits a radio frequency read When the signal is received, the radio frequency signal receiving unit of the anti-theft device of the non-contact IC card receives the radio frequency reading signal, and converts the radio frequency reading signal into an induced current. The induced current is rectified by the rectification unit and input to the radio frequency interference signal generated by the oscillation circuit. And transmitted through the antenna circuit. In the external space, the radio frequency interference signal and the read signal are mixed and superimposed, and the superimposed radio frequency signal after the superimposition is input into the non-contact IC card, because the non-contact IC card can only analyze the radio frequency read signal before superposition, Unable to parse the RF signal after the RF read signal and the RF interference signal are superimposed. Therefore, the non-contact IC card cannot generate the corresponding feedback RF signal after receiving the superimposed RF signal, resulting in that the NFC device cannot read the information of the non-contact IC card. .

Example two

An embodiment of the present invention provides another radio frequency identification circuit. As shown in FIG. 1, the IC card anti-theft device radio frequency identification circuit embodiment principle block diagram may specifically include the following modules: a radio frequency signal receiving unit, a rectification unit, an oscillation circuit, and interference. Signal generation unit. The radio frequency signal receiving unit is configured to receive the radio frequency reading signal of the NFC reading device and convert the radio frequency reading signal into an induced current; the rectifying unit rectifies the converted induced current; the oscillating unit passes the rectification The interference voltage is supplied to the oscillating unit to generate an interference signal. The interference signal transmitting unit sends the interference signal to the free space through the L-C capacitive-inductive parallel oscillation according to the interference signal generated by the oscillating circuit. The interference signal generating unit supplies power to the oscillating circuit according to the rectified current. A radio frequency interference signal, and sending the radio frequency interference signal.

As shown in FIG. 3, a schematic circuit diagram of an embodiment of a radio frequency identification circuit for a non-contact IC card immobilizer, the radio frequency signal receiving unit includes a first induction coil (L1) and a second capacitor (C2); According to the interference signal generated by the oscillating circuit, the transmitting unit sends the free space through the parallel oscillation composed of the second inductor (L2) and the first capacitor (C1).

Different from the first embodiment, in this embodiment, the rectifying unit includes a first diode (D1), a third capacitor (C3), and a fourth capacitor (C4) for detecting, A negative electrode of the first diode (D1) is connected to an output terminal of the radio frequency signal receiving unit through a fourth capacitor (C4), and a positive electrode is connected to an input terminal of the interference signal generating unit. The third capacitor (C3) is used for signal filtering and DC integration to obtain a pure DC signal without harmonics, which is beneficial to the stability of the system. The fourth capacitor (C4) is used for the rectification unit and the RF signal receiving unit. Isolation between them to minimize the mutual influence between the RF signal receiving unit, the interference signal generating unit and the oscillating unit

It should be noted that when working in a large signal environment, the first diode (D1) in the rectifier unit can use the HSMS-285x series of dual diodes to achieve self-biasing of the circuit under large signal conditions and achieve Multiplying effect of current improves detection efficiency.

Example three

An embodiment of the present invention provides a non-contact IC card anti-theft device, which includes the radio frequency identification circuit of the second embodiment or the third embodiment.

In summary, a radio frequency identification circuit and a non-contact IC card anti-theft device composed of the radio frequency identification circuit provided by the embodiments of the present invention have a simple structure and low implementation cost. Therefore, the embodiment of the present invention achieves the following technical effects: The non-contact IC card anti-theft device of the present invention can effectively prevent the non-contact IC card from being stolen by a criminal through an NFC reading device when not in use.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, but not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: It is still possible to modify the technical solutions described in the foregoing embodiments, or to replace some or all of the technical features equivalently; and these modifications or replacements do not depart from the essence of the corresponding technical solutions of the technical solutions of the embodiments of the present invention. range.

Claims

A radio frequency identification circuit, comprising:

A radio frequency signal receiving unit, configured to receive a radio frequency reading signal of an NFC reading device, and convert the radio frequency reading signal into an induced current;

A rectifying unit for performing half-wave rectification on the converted induction current;

The interference signal generating unit supplies power to the oscillation circuit according to the rectified current to generate a radio frequency interference signal, and sends the radio frequency interference signal out;

The radio frequency signal receiving unit includes a first induction coil (L1);

The rectifying unit includes a first diode (D1), a positive electrode of the first diode (D1) is connected to an output terminal of the radio frequency signal receiving unit, and a negative electrode is connected to an input terminal of the interference signal generating unit. connection;

The interference signal generating unit includes a first crystal (X1), a first transistor (Q1), a first resistor (R1), a first capacitor (C1), and a second induction coil (L2). The first resistor (R1) and the first crystal (X1) constitute a parallel circuit. One end of the parallel circuit is electrically connected to the base of the first transistor (Q1), and the other end is electrically connected to the first transistor (Q1). The collector of a triode (Q1) is electrically connected, and at the same time is electrically connected to the second inductor (L2) and the first capacitor (C1), the emitter of the first transistor (Q1) Ground.
The radio frequency identification circuit according to claim 1, further comprising a transmitting unit connected in series to the radio frequency signal receiving unit and the interference signal generating unit.
The radio frequency identification circuit according to claim 1 or 2, wherein the radio frequency signal transmitting unit comprises a second induction coil (L2), the second induction coil (L2), and the first capacitor. (C1) The parallel circuit constituted transmits the interference signal generating unit through an antenna.
A non-contact IC card anti-theft device, comprising a radio frequency identification circuit according to any one of claims 1-3.