JPH10240890A - 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 a positive characteristic thermister for controlling power 15 restricting the supply of overpower and when the card antenna 11 receives energy larger than power required by IC 14, the resistance value of the thermister 15 is increased to restrict extra energy 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 (R).
WU) 2 is performed in space (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 power supply circuit for supplying received energy of a card antenna to an IC through a regulator. This is achieved by providing a characteristic thermistor.

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 spatial transmission distance is shorter than the designed maximum transmission distance, the card antenna receives more energy than the IC requires, but the extra energy is It can be limited by the control of the limiting positive characteristic thermistor. 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 an 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, further adjusted by the regulator 13, and supplied to the IC 14. The drive power supply circuit for the IC 14 is provided with a positive temperature coefficient thermistor 15 for limiting the supply of overpower.

As the PTC thermistor 15 for power limitation, for example, a posistor (trade name) is used, and is disposed near the regulator 13. The posistor is a sintered body based on BaTiO ₃ and has a characteristic that the resistance value rapidly increases when a certain temperature or more is reached, and the current flowing through the circuit is limited by the increased resistance value.

The regulator 13 generates heat when excessive electric power is supplied. When the temperature rise of the regulator 13 is sensed by the posistor 15, the resistance value is increased to limit the current. Thus, heat generation of the regulator 13 can be suppressed, and stable IC driving can be performed.

As described above, data and power are transmitted between the RWU 2 and the card antenna 11 by electromagnetic coupling. At this time, if the contactless spatial transmission distance is shorter than the design value, the card antenna 11 Is provided in the power supply circuit from the card antenna 11 to the IC 14, a power limiting positive temperature coefficient thermistor 15 is provided, and a resistance value is increased by a temperature rise by the regulator 13 or the like, so that excess energy is limited. Is controlled, the heat loss of the IC card can be prevented even if the spatial transmission distance changes from the design value. This facilitates the non-contact installation between the RWU and the IC card.

[0012]

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 configuration diagram of an embodiment of the present invention.

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

[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
... Positive characteristic thermistor.

Claims (2)

[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 reception 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 positive-characteristic thermistor that limits supply of overpower by changing a resistance value according to temperature. 2. The non-contact IC card according to claim 1, wherein the positive temperature coefficient thermistor is a posistor (trade name) arranged near a regulator.