| 摘要 |
PROBLEM TO BE SOLVED: To make surely communicable with an IC card regardless of having the IC cards near to each other or the number of IC cards by setting the resonance frequency of a resonance circuit higher than the frequency of a signal for power. SOLUTION: When the IC card is inserted, it is read by a transmission circuit 5, the signal for power of the prescribed frequency is outputted from the transmission circuit 5 to a resonance circuit 7, and a radio wave signal for power is transmitted from an antenna coil 2. When a reader/writer 1 is to communicate with plural IC cards, the resonance frequency of the resonance circuit 7 is lowered by the mutual induction of the IC cards with the antenna coil but in the state of suppressing the power consumption of the resonance circuit 7 while securing sufficient antenna output, the plural IC cards can be surely communicated. Namely, by setting the resonance frequency of the resonance circuit 7 of the reader/writer 1 higher than the frequency of the signal for power, even when the resonance frequency of the resonance circuit 7 is lowered by the communication with plural IC cards, the sufficient antenna output is secured and the communication can be surely performed. |
