Patent ID: 8111137
Filing Date: 2012-02-07
Classification: B41J,G06K,H04B

Abstract:
1. An RFID tag reader/writer communicable with an RFID tag circuit element which has an IC circuit portion storing predetermined information, and an antenna connected to the IC circuit portion and arranged to effect transmission and reception of information, said RFID tag reader comprising: an access-information generating portion operable to obtain access to RFID tag information of said IC circuit portion, for reading and writing said predetermined information, by communication with said RFID tag circuit element; a carrier-wave generating portion operable to generate a carrier wave for obtaining access to said RFID tag information of said IC circuit portion; a carrier-wave modulating portion operable to modulate the carrier wave generated by said carrier-wave generating portion, by using access information generated by said access-information generating portion; a modulated-wave amplifying portion operable to amplify the carrier wave modulated by said carrier-wave modulating portion; and an antenna for transmitting an output of said modulated-wave amplifying portion to said IC circuit portion, for obtaining access to said RFID tag information, by non-contact radio communication with said IC circuit portion, by using a radio frequency, wherein a frequency of the carrier wave to be generated by said carrier-wave generating portion is determined on the basis of a resonance frequency of the antenna of said RFID tag circuit element located within a predetermined nearby communication area and the frequency of the carrier wave is adjusted so that the frequency of the carrier wave follows a change of the resonance frequency of the antenna of said RFID tag circuit element, where resonance frequency changes due to mutual coupling between the antenna of said RFID tag circuit element and the antenna of said RFID tag reader/writer.