Transmitter-receiver for non-contact IC card system
First Claim
1. A transmitter-receiver used for an interrogator in a non-contact IC card system which transmits and receives signals between the interrogator and a transponder said transmitter-receiver comprising:
- a carrier wave oscillating means capable of sweeping an oscillation frequency;
a resonant wave detecting means for detecting a single resonant frequency of the transponder among carrier waves generated by the carrier wave oscillating means;
a carrier frequency holding means for maintaining the oscillation frequency of the carrier wave oscillating means at said single resonant frequency detected by the resonant wave detecting means; and
means for transmitting data between the interrogator and the transponder at said single resonant frequency.
1 Assignment
0 Petitions
Accused Products
Abstract
In a non-contact IC card system which transmits and receives signals between an interrogator and a transponder, a transmitter-receiver used for the interrogator includes a carrier wave oscillator capable of sweeping an oscillation frequency, a resonant wave detector for detecting the resonant frequency of the transponder among carrier waves generated by the carrier wave oscillator, and a carrier frequency holder for maintaining the oscillation frequency of the carrier wave oscillator to the frequency detected by the resonant wave detector. The system is driven with a high transmission efficiency by bring the carrier wave frequency of the interrogator into agreement with the resonant frequency of the transponder, without lowering the Q value of the resonant circuit of the transponder and without any special adjustment for controlling the resonant frequency of the transponder to the desired frequency.
-
Citations
7 Claims
-
1. A transmitter-receiver used for an interrogator in a non-contact IC card system which transmits and receives signals between the interrogator and a transponder said transmitter-receiver comprising:
-
a carrier wave oscillating means capable of sweeping an oscillation frequency; a resonant wave detecting means for detecting a single resonant frequency of the transponder among carrier waves generated by the carrier wave oscillating means; a carrier frequency holding means for maintaining the oscillation frequency of the carrier wave oscillating means at said single resonant frequency detected by the resonant wave detecting means; and means for transmitting data between the interrogator and the transponder at said single resonant frequency. - View Dependent Claims (2, 3, 4)
-
-
5. A method for matching a frequency of an interrogator to a frequency of a transponder in a transmitter-receiver arrangement, comprising:
-
varying a carrier frequency of the interrogator; locating the transponder within a signal coupling range of the interrogator; detecting a peak signal in said interrogator which corresponds to a single resonant frequency in the transponder; holding the carrier frequency of the interrogator at the single resonant frequency upon detection of the peak signal; and transmitting data between the transponder and the interrogator while the interrogator holds the carrier frequency of the transponder at said single resonant frequency. - View Dependent Claims (6, 7)
-
Specification