NON-CONTACT INFORMATION MEDIUM AND NON-CONTACT IC CARD SYSTEM

摘要

PROBLEM TO BE SOLVED: To eliminate the need of the filter having a steep characteristic for distributing transmission and reception by loading a phase locked loop circuit on a card and generating a carrier used in modulation/demodulation and the operation clock of a processor through the use of the circuit. ;SOLUTION: The phase locked loop circuit 14 is loaded on the non-contact IC card 1. At the time of transmitting data from the card 1 to a read/write device 2, the input voltage of the voltage control oscillator of the phase locked loop circuit 14 is held. Thus, a synchronizing operation is set to a state that it is temporarily stopped from a state that it is synchronized with a reference signal from the read/write device. Thus, the phase locked loop circuit 14 continuously outputs the signal of a prescribed frequency. The card 1 generates the carrier and the operation clock of the processor 12 by using the output of the phase locked loop circuit 14. Thus, the synchronous shift of the frequency and the phase, which occur during that time, is corrected by the phase locked loop circuit 14 at the time of transmitting data from the read/write device 2 to the card 1. Then, data are transmitted/received between the card 1 and the device 2 by repeating the operation.;COPYRIGHT: (C)1999,JPO