Patent ID: 7487921
Filing Date: 2009-02-10
Classification: G06K

Abstract:
1. A reader/writer performing radio communication with a radio communication terminal in close proximity thereto, comprising: an antenna for transmitting a carrier wave of a predetermined frequency and receiving a composite wave of said carrier wave and a modulated signal of a signal having the frequency identical to that of said carrier wave transmitted from said radio communication terminal; a demodulating unit for demodulating the composite wave received by said antenna; a judging unit for judging whether a null state has occurred when said radio communication terminal is in close proximity; and a carrier-wave control unit having an auxiliary antenna provided in the proximity of said antenna for reducing a component of said carrier wave input into said demodulating unit by wirelessly transmitting a signal of a reverse phase to said carrier wave from the auxiliary antenna when said judging unit judges that the null state has occurred.