JP2631664B2 - Non-contact magnetic coupling transmission / reception method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact magnetic coupling transmission / reception system, and more particularly, to an improvement in a non-contact IC card transmission / reception system.

[Prior Art] A non-contact type IC card, a host computer into which the IC card is inserted, and an IC card reader / writer (hereinafter simply referred to as a reader / writer).
Data write / read device (or host device) such as writer)
When data communication is performed with the IC card, both the reader / writer and the IC card are provided with a transmission circuit and a reception circuit, and data transmission and reception are performed via these transmission / reception circuits.

In the case of transmitting and receiving between these IC cards and a reader / writer by non-contact type magnetic coupling (or electromagnetic coupling, hereinafter referred to as magnetic coupling), in order to generate a carrier wave for transmitting a signal, each transmission is performed. A circuit requires a carrier generation circuit, and the circuit has a considerably complicated configuration. Therefore, there is a disadvantage that the size of the circuit and the thickness of the card cannot be reduced.

[Problem to be Solved] The present invention has a transmission circuit on both sides that occur when a data writing / reading device of such a conventional product and a storage medium such as an IC card are magnetically coupled in a non-contact manner. It is an object of the present invention to provide a non-contact type magnetic coupling transmission / reception system which can solve the drawback that it is necessary to simplify the circuit on the storage medium side.

[Means for Solving the Problems] To achieve such an object, the configuration of the non-contact type magnetic coupling transmission / reception system according to the present invention is such that the first transmission / reception device and the second transmission / reception device are in a non-contact state. In the transmission / reception system which is magnetically coupled at and transmits / receives a signal, the first transmission / reception device includes:
A first magnetic flux generating circuit for the magnetic coupling, and a carrier wave generating circuit connected to the magnetic flux generating circuit and generating a carrier wave for carrying a signal to a second transmitting / receiving device;
Has a second magnetic flux generating circuit for magnetic coupling, and a circuit connected to the second magnetic flux generating circuit for changing the load impedance of the second magnetic flux generating circuit according to a transmission signal. The first transmission / reception device detects a change in the frequency of the carrier wave and receives the transmission signal from the second transmission / reception device.

[Operation] Taking an example of an IC card, the present invention provides a power supply circuit for converting a vibration energy field formed in a space into DC power, a power supply circuit using a battery as a power supply, and an oscillation circuit for a reader / writer. A coil inserted into the created magnetic field, a circuit that detects and rectifies the energy obtained by this coil and converts it into a signal, and a circuit that changes the resonance frequency of the space by connecting and disconnecting (ON-OFF) the state of this coil And a processing circuit for performing data processing, wherein an IC card that drives all of the circuits with the power obtained by the power supply circuit is used as the second transmitting / receiving device, and a carrier wave of a signal transmitted to the IC card is provided. An IC card reader / writer provided with an oscillation circuit to generate and a reader / writer or a host computer or the like having a frequency comparison circuit for demodulating a change in the frequency of the oscillation circuit and converting it into data. It is an transceiver device.

In this way, the reader / writer has a carrier oscillation circuit and a frequency comparison circuit, and the IC card consists of a circuit that detects and rectifies the energy obtained from the coil and converts it into data, and a circuit that connects and disconnects the state of the coil. Hold it on the side
When data is transmitted from the writer to the IC card, the oscillation circuit is operated to receive energy by the coil, and the state of the oscillation circuit is disconnected to transmit data to the IC card. On the other hand, when transmitting data from the IC card side to the reader / writer side, the oscillation circuit is kept operating, and the connection state of the coil is cut off (for example, grounded) according to the data to be transmitted. The change in the oscillating frequency of the oscillating circuit due to the change in impedance caused by this is input to the frequency comparing circuit, and the change in the oscillating frequency is received as reception data.

As described above, by changing the impedance of the magnetic flux generation circuit on the first transmission / reception device side on the second transmission / reception device side, the resonance frequency of the carrier wave generation circuit is changed. A configuration that does not have an oscillation circuit on the transmission / reception device side can be adopted.

As a result, the transmission circuit of the second transmission / reception device can be simplified and the reliability can be improved due to the reduction in the number of components, and the effect is particularly large when applied to an IC card.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of transmission and reception of a non-contact type IC card to which the non-contact type magnetic coupling transmission and reception system of the present invention is applied.

In FIG. 1, reference numeral 1 denotes an IC card reader / writer into which a non-contact type IC card 2 (hereinafter simply referred to as IC card 2) is inserted.
The signal is received from the oscillating circuit 4 of the writer 1 via the transmitting coil 12 and the receiving coil 13 which is magnetically coupled with the transmitting coil 12 in a non-contact state. In this case, the oscillation circuit supplies a signal of, for example, about 200 kHz to the transmission coil 12, and the reception coil 13 receives the signal in the form of a magnetic field, and power is transmitted. This power received by the receiving coil 13 is then converted by the rectifier circuit 8 into DC voltage power,
It is supplied to each circuit of the card 2.

Reference numeral 3 denotes a power supply circuit provided in the reader / writer 1, which supplies power to the circuits of each unit.

On the other hand, data transmitted from the reader / writer 1 to the IC card 2 is transmitted by a data processing device 6 having a microprocessor or the like via an oscillation circuit 5 and a transmission / reception coil 14 connected thereto. Here, the oscillation circuit 5 generates a carrier wave having a frequency of, for example, about 10 MHz, and outputs “ON-OFF” according to transmission data from the data processing device 6.
Is done. That is, data transmission is performed by a so-called tone burst method.

In this way, the transmission / reception coil 14 is
Transmitted in the form of a magnetic field through the transmission / reception coil 15 of the IC card 2, which is magnetically coupled in a non-contact state with the data, is demodulated into a digital signal by the detection rectifier circuit 9, and is processed by a data processing device having a microprocessor or the like It is sent to the circuit 11.

On the other hand, data transmission from the IC card 2 to the reader / writer 1 is performed while the oscillation circuit 5 of the reader / writer 1 is kept oscillating.
By operating the switching circuit 10 connected to the connection point of the detection and rectification circuit 9 and turning the connection point “ON-OFF” in accordance with the transmission data, and performing intermittent control in accordance with the transmission data. You.

Here, as the “ON-OFF” control of the switching circuit 10, when the switching circuit 10 is “OF”, a bias voltage or a power supply voltage is applied to a terminal of the transmitting and receiving coil 15 connected to the detection rectifier circuit 9 side. A DC current flows, and this terminal is grounded when it is OFF.

This is to generate a magnetic flux due to a direct current in the transmitting and receiving coil 15 when "ON", and to erase the magnetic flux when "OFF". This "ON-OFF" control causes the magnetic circuit of the transmitting and receiving coil 14 to be turned off. The impedance can be changed, which changes the output frequency of the oscillation circuit 5.

Similarly, to change the impedance of the magnetic circuit, the terminal connected to the detection and rectification circuit 9 side of the transmission and reception coil 15 is disconnected from the detection and rectification circuit 9 side, and both terminals of the transmission and reception coil 15 are open when “OFF”. These terminals may be short-circuited directly or via a resistor at the time of “ON”. The switching circuit 10 has such an “ON-OF
In the case of performing F "control, the transmission / reception coil 15 is not a circuit that generates a magnetic flux unlike the former, but is simply a transmission / reception coil.
It is electromagnetically coupled to 14 and functions as a magnetic coupling circuit that changes the impedance of the magnetic circuit.

The output frequency of the oscillation circuit 5 is changed by the "ON-OFF" control of the switching circuit 10, and this is detected by the frequency comparison circuit 7, and the transmission data is demodulated.

That is, since the transmission / reception coil 14 is electromagnetically coupled with the transmission / reception coil 15, a change in load impedance on the transmission / reception coil 15 side becomes a signal, which is
After 14, the output signal of the oscillation circuit 5 is modulated,
As a result, a signal whose frequency changes is obtained on the connection side of the oscillation circuit 5 with the transmission / reception coil 14.

The frequency change portion is compared with a reference carrier frequency without modulation of the oscillation circuit 5 in the frequency comparison circuit 7 to detect transmission data from the IC card 2 side, demodulate the carrier signal based on the detected data, and transmit the data. Get the data. In addition,
The signal of the reference carrier frequency here is obtained from the oscillation element in the oscillation circuit 5 or its peripheral circuit, a separately provided clock oscillator, or the like.

The transmission data thus detected is transmitted to the reader / writer 1
Is transmitted to the data processing device 6 and processed as transmission data from the IC card 2.

In this embodiment, the power supply circuit of the IC card 2 is as follows.
Although it is made by a magnetic flux generation circuit, this may be obtained by using energy such as a solar cell or ultrasonic waves,
Further, a battery built-in type may be used.

As described above, in the embodiment, the change in the frequency is detected by using the comparison circuit. This is performed by extracting a specific frequency by filtering or the like, detecting the transmission data, and shaping the waveform. May be used to demodulate the transmission data, and may be any circuit that can detect a change in frequency.

Further, in the embodiments, the description has been made centering on the IC card, but it is needless to say that the present invention can be applied to various information storage media such as other memory cards having a built-in microprocessor and the like and memory cartridges. Further, the present invention can be applied to a non-contact type magnetic coupling transmission / reception system between general apparatuses which perform transmission / reception using magnetic coupling in a non-contact type.

[Effects of the Invention] As described above, according to the present invention, data can be transmitted / received by changing the resonance frequency, and a second transmission / reception device, for example, a configuration without an oscillation circuit on the IC card side can be adopted. In addition, simplification of a data transmission circuit such as an IC card and improvement in reliability due to a reduction in the number of components can be achieved.

[Brief description of the drawings]

FIG. 1 is a block diagram of transmission and reception of a non-contact type IC card to which the non-contact type magnetic coupling transmission and reception system of the present invention is applied. DESCRIPTION OF SYMBOLS 1 ... Reader / writer, 2 ... IC card, 3 ... Power supply circuit, 4 ... Oscillation circuit, 5 ... Oscillation circuit, 6 ... Data processing circuit, 7 ... Frequency comparison circuit, 8 ... Rectifier circuit 9 Detector rectifier circuit 10 Switching circuit

Claims (4)

(57) [Claims] In a transmission / reception system in which a first transmission / reception device and a second transmission / reception device are magnetically coupled in a non-contact state to transmit and receive signals, the first transmission / reception device includes a first transmission / reception device for the magnetic coupling. Connected to this magnetic flux generating circuit and
A carrier generation circuit for generating a carrier wave for carrying a signal to the second transmission / reception device, wherein the second transmission / reception device includes a second magnetic flux generation circuit for the magnetic coupling and the second magnetic flux generation device A circuit connected to a circuit and changing a load impedance of the second magnetic flux generation circuit in accordance with a transmission signal, wherein the first transmission / reception device converts a transmission signal from the second transmission / reception device into a frequency change of the carrier wave. A non-contact type magnetic coupling transmission / reception method characterized in that a state is detected and received. 2. The first magnetic flux generating circuit according to claim 1, wherein the second magnetic flux generating circuit is a magnetic coupling circuit that does not generate a magnetic flux.
Non-contact type magnetic coupling transmission / reception method described in the item. 3. The first transmission / reception device is a data writing / reading device, the second transmission / reception device is an IC card, and the first and second magnetic flux generating circuits are each formed of a coil. The load impedance of the magnetic flux generating circuit is changed by grounding or opening the connection state of the circuit.
Non-contact type magnetic coupling transmission / reception system described in the item. 4. A method for detecting a change state of a carrier wave by comparing a carrier frequency serving as a reference of a carrier wave generation circuit with a frequency output from a first magnetic flux generation circuit of the carrier wave generation circuit. The non-contact magnetic coupling transmission / reception system according to claim 2 or 3, wherein: