NON-CONTACT IC CARD READER-WRITER

摘要

PROBLEM TO BE SOLVED: To operate a reader-writer (R/W) for the IC card of an electromagnetic induction type operated under non-contact state with small power consumption. SOLUTION: At a magnetic coupling position near a first antenna coil 11 of the R/W 1 for the non-contact IC card of the electromagnetic induction type, a second antenna coil 21 resonating at the frequency of a carrier wave generated by the first antenna coil 11 or the frequency near it is installed. Electric characteristic at both ends of the second antenna coil 21 are changed by switching impedance by a switch circuit part 26, the strength of the carrier wave transmitted from the first antenna coil 11 is changed, the signals of a modulation degree of ASK less than 100% are transmitted and information is transmitted to/received from the non-contact IC card 2. Thus, the signals of the modulation degree of ASK less than 100% are transmitted without using an amplifier circuit or complicated circuit constitution and the operation is performed with the small power consumption.