RF TAG SYSTEM AND POWER TRANSMITTER

PROBLEM TO BE SOLVED: To provide an RF tag system in which a communication distance can be set more flexibly, without taking the trouble to perform management of battery replacement, and the like. SOLUTION: An RF tag is equipped with a power generator which generates electric power for operation of itself from a carrier transmitted from a reader/writer 2 and a power storage unit which stores supply power for operation of itself, and is configured to execute, as an operation mode, a passive mode wherein the RF tag operates with the electric power supplied from the power generator to answer by a back-scatter system and an active mode wherein the RF tag operates with the electric power supplied from the power storage unit to answer by modulating the carrier to be transmitted by itself. Then the reader/writer 2_2, when operating in the power supply mode operates not with the purpose of communicating with the RF tag 1, and transmits the unmodulated carrier. COPYRIGHT: (C)2009,JPO&INPIT