Patent ID: 7240837
Filing Date: 2007-07-10
Classification: G06K

Abstract:
1. A radio data communication apparatus, comprising: a plurality of first antennas configured to perform a one-to-one radio communication with a plurality of second antennas of IC tags having communication frequencies different from each other, the one-to-one radio communication being carried out based on a resonance frequency uniquely assigned to each one of combinations between the plurality of first antennas and the plurality of second antennas; a plurality of modulation circuits connected to the plurality of first antennas on a one-to-one basis, and each configured to perform a modulation function for modulating a carrier wave in accordance with data to be transmitted and transmitting the modulated carrier wave to a specific IC tag among the plurality of IC tags through a corresponding one of the plurality of first antennas and a demodulation function for demodulating a modulated carrier wave which has been sent from a specific IC tag out of the plurality of IC tags via a corresponding one of the plurality of first antennas; an oscillating circuit configured to generate and output a plurality of carrier waves having frequencies different from each other, the frequencies being predetermined in accordance with a specific factor; a switch circuit configured to exclusively select and output one of the plurality of carrier waves output from the oscillating circuit in accordance with a control signal input thereto; a memory storing communication information of each one of the plurality of IC tags, including a resonance frequency assigned thereto; and a control circuit configured to read from the memory a specific resonance frequency assigned to one of the plurality of second antennas belonging to a target IC tag among the plurality of IC tags, to generate the control signal such that the switch circuit selects, from among the plurality of carrier waves, a specific carrier wave having a frequency, out of the predetermined frequencies, substantially equal to the specific resonance frequency read from the memory, and to transmit the specific carrier wave selected by the switch circuit and data to be transmitted in synchronism with each other to a corresponding one of the plurality of modulating circuits, wherein the predetermined frequencies are within the radio wave spectrum.