JPH10240889A - Noncontact ic card - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a noncontact IC card provided with a means for suppressing the generation of heat due to overpower transmission. SOLUTION: RWU(read/write unit) and a noncontact IC card are arranged separated by a transmission space 3 to transmit data and power by the electromagnetic combination of a coil mounted to RWU and an IC card antenna. The received energy of a card antenna 11 is supplied as driving power for IC 14 through a rectifying circuit 12 and a regulator 13. The power supplying circuit is provided with an on/off switch for restricting power 17 restricting the supply of overpower and when the card antenna 11 receives energy larger than power required by IC 14, the switch 17 is turned off to make a parallel resistor 16 consume extra energy to restrict to suppress the heat generation of IC 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact IC card, and more particularly to a non-contact IC card in which supply of overpower is restricted.

[0002]

2. Description of the Related Art As shown in FIG. 2, a non-contact IC card includes a non-contact IC card 1 and a read / write unit (P / P).
WU) 2 is performed by spatial transmission (non-contact) 3. The non-contact IC card 1 has a built-in battery and a non-built-in battery for driving the IC, but the latter needs to be supplied with power from the outside. To supply power from the outside, a coil is mounted on the non-contact IC card 1 and the RWU 2, and power is transmitted by electromagnetic coupling.

[0003]

The power transmission is designed so that the IC card 1 and the RWU 2 can be supplied with the power required to drive the IC while keeping the IC card 1 and the RWU 2 apart by a certain distance (maximum transmittable distance). Have been. Therefore, when the distance between the IC card 1 and the RWU 2 is shorter than the maximum transmittable distance, the IC card 1 receives energy larger than the power required by the IC. This extra energy is converted into heat in the IC card, and the heat directly damages the IC or deforms the synthetic resin, which is the base material of the IC card, to destroy the IC.

[0004] An object of the present invention is to provide a non-contact IC card provided with means capable of suppressing heat generation due to this overpower transmission.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a circuit for supplying received energy of a card antenna to an IC through a regulator by using a power limiting on / off switch for limiting the supply of overpower by on / off switching control. It is achieved by providing.

According to the above means, data and power are transmitted between the read / write unit and the IC card antenna by electromagnetic coupling. If the contactless transmission spatial distance is shorter than the maximum designable transmission distance, the card antenna receives more energy than the IC requires, but the extra energy is It can be limited by the on / off control of the limiting on / off switch. Thereby, heat generation of the IC can be suppressed, and breakage, deformation, and the like can be prevented.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a basic embodiment of the non-contact IC card of the present invention. Power for driving the IC is transmitted from the RWU 2 by the card antenna 11 electromagnetically coupled to the RWU coil. The power received by the card antenna 11 is rectified by the rectifier circuit 12, adjusted by the regulator 13, and supplied to the IC 14. The driving power supply circuit for the IC 14 is provided with a circuit 15 for limiting the supply of overpower. This power limiting circuit includes a current control resistor 16 and an on / off switch 17 for short-circuiting both ends of the resistor 16.

The on / off switch 17 normally turns on to short-circuit the resistor 16, but the card antenna 11
When excessive power flows from the IC to the IC, the switch is turned off and the current is limited by the resistor.

FIG. 3 shows a specific configuration of an embodiment of the present invention. The same reference numerals as those in FIG. 1 denote the same parts. Semiconductor switches 171 such as transistors and FETs are used as on / off switches. Then, the voltage input to the regulator 13 is detected by the voltage detection circuit 18, and when the voltage becomes equal to or higher than a certain voltage, the semiconductor switch 171 is controlled to be turned off. When the semiconductor switch 171 is turned off, the current is limited by the resistor 16 and the heat generation of the regulator 13 is suppressed. When the input voltage to the regulator 13 decreases, the semiconductor switch 171 is turned on to increase the supplied power, so that the driving power to the IC 14 does not become insufficient, and the IC is driven stably by a predetermined power supply. Can be.

FIG. 4 shows another embodiment of the present invention, in which a temperature switch 172 is arranged near the regulator 13. The temperature switch 172 is a temperature-sensitive reed switch,
A temperature relay or the like is used, and when the temperature exceeds a certain temperature, the switch is turned off and the current flows to the resistor 16 to limit the current. As a result, the amount of heat generated by the regulator 13 due to excessive power can be suppressed, and stable IC driving can be performed.

As described above, the RWU and the card antenna 11
When data and power are transmitted by electromagnetic coupling, if the non-contact spatial transmission distance is shorter than a design value, excessive power is received by the card antenna 11,
The power supply circuit from the card antenna 11 to the IC 14 is provided with on / off switches 17, 171, and 172 for power limitation, and controls the drive power of the IC by limiting the excess energy by switching off. In addition, even if the space transmission distance changes from the design value, it is possible to prevent heat damage of the IC card. This facilitates the non-contact installation between the RWU and the IC card.

[0013]

As described above, according to the present invention, the non-contact I
It is possible to prevent the C card from being damaged by heat,
A non-contact IC card having excellent durability can be obtained.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of an embodiment of the present invention.

FIG. 2 is an image diagram of a non-contact IC card.

FIG. 3 is a configuration diagram of an embodiment of the present invention.

FIG. 4 is a configuration diagram of another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Contactless IC card, 2 ... Read / write unit (RWU), 3 ... Transmission space, 11 ... Card antenna, 1
2: Rectifier circuit, 13: Regulator, 14: IC, 15
... power limiting circuit, 16 ... resistor, 17 ... on / off switch, 18 ... voltage detection circuit, 171 ... semiconductor switch, 1
72. Temperature switch.

Claims (3)

[Claims] 1. A contactless IC card for transmitting data and power by electromagnetic coupling across a transmission space between a read / write unit and a card antenna connected to an IC, wherein the received energy of the card antenna is transmitted to the IC through a regulator. A non-contact IC card characterized in that a power supply circuit to be supplied is provided with a power limiting on / off switch for limiting the supply of overpower by on / off switching control. 2. The non-contact IC card according to claim 1, wherein the on / off switch is a semiconductor device controlled by an input voltage of a regulator. 3. The non-contact IC card according to claim 1, wherein the on / off switch is a temperature switch controlled by a temperature of a regulator.