Non-contact IC card with phase variation detector

Patent 5874725 Issued on February 23, 1999. Estimated Expiration Date:

August 1, 2017. 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

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Inventor

Yamaguchi, Atsuo

Application

No. 905132 filed on 08/01/1997

US Classes:

235/492, Conductive235/439, Particular sensor structure340/5.61, Wireless transceiver340/10.34Power up

Examiners

Primary: Gross, Anita Pellman
Assistant: Lee, Michael G.

Attorney, Agent or Firm

Leydig, Voit & Mayer

Foreign Patent References

0281142 EP. 09/14/1988
0453314 EP. 10/14/1991
3707173 DE. 09/14/1987
58-154081 JP. 09/14/1983
58-154080 JP. 09/14/1983
58-151722 JP. 09/14/1983
5128319 JP. 05/14/1993
5135224 JP. 06/14/1993
WO8905067 WO. 06/14/1989

International Class

G06K 009/06

Foreign Application Priority Data

1994-10-06 JP

Abstract

A batteryless non-contact IC card, using electromagnetic waves as a communication medium, includes an antenna resonance circuit for data transmission and reception; a phase variation detector for detecting a phase variation of a voltage of the antenna resonance circuit due to a received signal, on the basis of an amplitude variation of the received signal; and a demodulator for demodulating data in accordance with the phase variation detected by the phase variation detector.