| 摘要 |
PURPOSE:To increase the communication distance by allowing a data demodulation means of 2nd unit to data demodulate a signal based on the pulse width in the data transmission between 1st and 2nd units through electromagnetic coupling to reduce power consumption. CONSTITUTION:Semi-duplex data transmission of a serial data is executed between the 1st and 2nd units 1, 3 by utilizing electromagnetic coupling. A data demodulation means 42 of the 2nd unit 3 demodulates a signal based on a pulse width, then no PLL circuit is required, and power consumption goes to small. Thus, in case of the power of the 2nd unit 3 obtained from the 1st unit, the transmission distance is extended because the power consumption is small. Moreover, in the transmission of a data from the 2nd unit 3 to the 1st unit 1, since the echo of the signal obtained from the 1st unit 1 is controlled based on the transmission data, the data transmission distance is extended. Since the frequency used for resonance circuits 17, 30 of the 1st and 2nd units 1, 3 is made coincident with the oscillated frequency of the oscillator 15, the data transmission is attained with high efficiency. |
