| 摘要 |
PURPOSE: To reduce the consumption of power at the time of transmission of a read/write head by providing a transmission control circuit, a resonance circuit, an oscillation part and a switching element in a write/read control unit. CONSTITUTION: For the read/write head 2, the oscillation part 21, a transistor TR1 for switching connected to it, a resistor R2 and the resonant circuit 16 are connected and the coil L1 for transmission of the resonant circuit 16 is provided on the surface opposite to a data carrier 3. The oscillation part 21 originates carrier signals whose duty factor is less than 50% at a fixed carrier frequency higher than transmission pulse signals only while the transmission from a transmission control circuit 11 is at an H level. Also, in a reception circuit, the resonance circuit 17 composed of the coil L2 and a capacitor C2 is provided and the output of the resonant circuit 17 is demodulated by a demodulation circuit 18 and supplied to a reception control circuit 13. Thus, transmission power is reduced without lowering the communication distance so much. |
