Non-contact, electromagnetically coupled transmission and receiving system for IC cards

Patent 5418353 Issued on May 23, 1995. Estimated Expiration Date:

October 19, 2014. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

Electronic data communications system
Patent #: 4814595
Issued on: 03/21/1989
Inventor: Gilboa

Identification system
Patent #: 4818855
Issued on: 04/04/1989
Inventor: Mongeon , et al.

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Patent #: 4899036
Issued on: 02/06/1990
Inventor: McCrindle, et al.

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Patent #: 4918416
Issued on: 04/17/1990
Inventor: Walton, et al.

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Patent #: 4924171
Issued on: 05/08/1990
Inventor: Baba, et al.

Method and apparatus for communication for a data-storing token
Patent #: 4928000
Issued on: 05/22/1990
Inventor: Eglise, et al.

Method and system of communication for a non-contact IC card Patent #: 5113184
Issued on: 05/12/1992
Inventor: Katayama

Inventors

Assignee

Application

No. 325643 filed on 10/19/1994

US Classes:

235/380, Credit or identification card systems235/375, SYSTEMS CONTROLLED BY DATA BEARING RECORDS235/376, Operations analysis235/487, RECORDS235/492Conductive

Examiners

Primary: Pitts, Harold I.

Foreign Patent References

0147099 EP. 07/13/1985
0267009 EP. 05/13/1988
0430291 EP. 06/13/1991
2198014 GB. 06/13/1988
WO8810433 WO. 12/13/1988
WO8901208 WO. 09/13/1989

International Class

G06K 005/00

Foreign Application Priority Data

1991-07-23 JP

Abstract

A non-contact IC card communication in which power consumption of a driver of a reader/writer is reduced and the size of a power supply circuit for operating the driver is made small. The driver has a low output impedance. A current detecting circuit including a detecting coil magnetically coupled with a transceiver coil of the reader/writer through a magnetic coiling element and a resistor detects a current which flows through the transceiver coil. A voltage drop to be detected is small and is approximately constant for a variation of the transceiver coil current. When data is read from an IC card, a load of the driver is changed. The driver drives the transceiver coil in a constant voltage fashion even if a current flowing through the transceiver coil changes due to the change in load. Input voltages of a rectifying/smoothing circuit and a regulator in the IC card become approximately constant. As a result, the amplitude of a high frequency output voltage of the driver can be made small. Also, a high frequency signal current sent from a reader/writer is subjected to double modulation including amplitude modulation by card data and modulation by second information, such as information indicative of the abnormality of an IC card, in synchronism with a timing at which data transmission between the reader/writer and the card is made, and the second information is extracted by the reader/writer.