JP3065169B2 - Non-contact type IC card - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact type IC card, and more particularly to a non-contact type IC card having a simple circuit structure and having a small angle dependency (with respect to the plane of polarization of an antenna in the card).

[0002]

2. Description of the Related Art In a moving object identification system, for example, a non-contact type IC card is used. In the case of identifying a person who moves while holding such a card, when a carrier emitted from the identification device is received by the card, the card modulates the received carrier based on data held in advance. To fire. Such an identification system is, for example, a mobile identification device standard RCR STD
-1.

Heretofore, the cards used in such identification systems have been provided with separate transmitting and receiving antennas and have required separate circuits or elements for at least demodulation and modulation.

[0004]

In such a card, transmitting and receiving antennas are separately provided, and circuit means for demodulating a received signal and modulating a signal to be transmitted are provided. Therefore, the circuit is complicated, and a compact circuit suitable for incorporating a card cannot be obtained.

In the above-mentioned card, since the polarization (plane) of the antenna in the card is usually linear and constant, there is a problem that the sensitivity is lowered depending on the angle between the card and the identification device. is there. To solve such a problem, a so-called circularly polarized carrier wave whose phase is orthogonally shifted from the identification device can be improved to some extent, but the angle of the card (the angle of the antenna in the card) can be improved. Depending on the case, a dead zone may occur.

[0006] The present invention solves the above problems,
Non-contact type I with compact antenna and circuit
The purpose is to provide a C card.

The present invention also provides an easy-to-use non-contact type IC having a small angle dependence on the plane of polarization of the antenna in the card.
The purpose is to provide the card.

[0008]

According to the present invention, a non-contact type used for identification by receiving a predetermined carrier from the outside, modulating the carrier based on data held in advance, and transmitting the modulated carrier. IC card is data
Antenna for transmission and reception , Schottky barrier diode connected to the antenna, and Schottky barrier diode
Waveform shaping to convert demodulated signals to digital signals
Means and storage means for storing unique data in advance
And the unique data read from the storage means at the time of transmission.
Switch means for outputting to an antenna,
The shaping means is provided via a Schottky barrier diode.
The Schottky barrier diode is electrically connected to the antenna, and is used as a demodulation unit for data reception and a modulation unit for data transmission.

Further, according to the present invention, the antenna is constituted by two antennas are orthogonal to each other, Schottky barrier diodes are respectively connected in series to the two antennas.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a non-contact type IC card according to the present invention.

FIG. 1 shows an embodiment of a non-contact type IC card according to the present invention. Card 10 is antenna 1
2, and a Schottky barrier diode D is connected to the antenna 12. When an amplitude-modulated carrier for writing data is emitted from the identification device, the carrier is received by the antenna 12 and the Schottky barrier diode D
Demodulates the data. In response from the card, a non-modulated carrier wave is emitted from the identification device. When a reflected wave is emitted by the antenna 12, the carrier is modulated based on the voltage applied to the Schottky barrier diode D.
As is well known, the Schottky barrier diode D can be used not only for demodulation like a normal diode, but also as a modulator for transmission in the present embodiment because its terminal capacitance changes depending on the applied voltage. Is done.

The antenna 12 has a resistor R and a comparator 1
The control unit 18 is connected via the control unit 6, and a memory 20 is connected to the control unit 18. The antenna 12 also controls the control unit 1 via a resistor R, a switch SW, and a comparator 22.
8 is connected. The switch SW is turned off at the time of data reception and turned on at the time of transmission by operating means (not shown).

The comparator 16 converts a signal received from the antenna 12 and demodulated by the Schottky barrier diode D into a digital signal by comparing the signal with a predetermined threshold value. The digital signal output from the comparator 16 is sent to the control unit 18 and written into the memory 20 as data.

At the time of transmission, that is, a response, the control unit 18
The memory 20 is controlled to read data stored in the memory 20. Based on this data, the modulation data output from the control unit 18 is sent to the antenna 12 through the switch SW and the resistor R. The voltage applied to the Schottky barrier diode D changes based on the modulation data sent to the antenna 12, and the carrier received by the antenna 12 is modulated and emitted from the antenna 12 as a reflected wave.

The card further has a power supply 24,
Supplies power to each part of the card. The power supply 24
May be used to extract power energy from electromagnetic waves of different frequencies supplied from the identification device using a coil, an antenna, or the like, or energy such as light may be used.

For supplying power to the card, a dedicated device (for power supply) may be separately provided in addition to the identification device.

FIG. 2 shows another embodiment of the non-contact type IC card according to the present invention. In this example,
Transmitting and receiving antennas 12a and 12b and antenna 12
c and 12d are arranged orthogonally. Antenna 12a
Between Schottky barrier diode D1 and
However, a resistor R2 is provided between the antennas 12b and 12c.
A Schottky barrier diode D2 is arranged between the antennas 12c and 12d. The antenna 12a is connected to the comparator 16 via the resistor R1 as in the embodiment of FIG. The antenna 12d is grounded via the resistor R3. Therefore, in this card, two antennas are connected in series.

Also in this card, the Schottky barrier diodes D1 and D2 are used not only for demodulation but also for modulation. The resistors R1 to R3 are high-frequency insulating resistors.

In this card, two antennas which are orthogonal to each other in one plane are provided, and a plane of polarization is not selected for an electromagnetic wave perpendicularly incident on this plane. Angle dependence can be reduced. Therefore, the angle dependency of the antenna in the card on the plane of polarization does not decrease depending on the direction of the card holder, so that there is no problem in the identification system using this card.

[0020]

According to the non-contact type IC card of the present invention,
Since the Schottky barrier diode is used for both demodulation means for reception and modulation means for transmission, the antenna can be used for both transmission and reception, and the circuit for demodulation and modulation can be simplified. Therefore, a compact circuit suitable for incorporating a card can be realized.

Furthermore, if two antennas which are orthogonal to each other are used, the plane of polarization is not selected for electromagnetic waves which are perpendicular to the plane on which the antennas are arranged. A simple identification system can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a non-contact type IC card according to the present invention.

FIG. 2 is a block diagram showing another embodiment of the non-contact type IC card according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 IC card 12 Antenna 16 Comparator 18 Control part 20 Memory 22 Comparator 24 Power supply D, D1, D2 Schottky barrier diode SW switch R1, R2, R3 Resistance

Claims (2)

(57) [Claims] 1. A which receives a predetermined carrier from the outside, after modulating based on data held in advance the carrier, in the non-contact type IC card that is used to identify by transmitting, the card data A transmitting / receiving antenna, a Schottky barrier diode connected to the antenna, and a signal demodulated by the Schottky barrier diode.
Waveform shaping means for converting to a digital signal, storage means for storing unique data in advance, and the unique data read from the storage means at the time of transmission
Switch means for outputting a signal to the antenna.
And the waveform shaping means includes the Schottky barrier diode.
Wherein the Schottky barrier diode is electrically connected to the antenna via the antenna, and the Schottky barrier diode is used as a demodulation unit for reception and a modulation unit for transmission. 2. A according to claim 1 card, the antenna is constituted by two antennas mutually orthogonal, the Schottky barrier diode, characterized in that it is connected in series to each of the two antennas Non-contact type IC card.