| 摘要 |
PURPOSE:To reduce the power consumption at the time of waiting by combining low and high frequency signal light beams at the sender side and receiving a high frequency modulation signal light beam after receiving the signal light beam of the low frequency at first at the reception side. CONSTITUTION:When a signal is inputted from a terminal T1, the high frequency modulation signal light modulated by the signal is radiated from a light emitting element 3a and a switch circuit 10 is operated simultaneously and the low frequency signal light is radiated from a light emitting element 3b. Power is supplied from a battery 9 only to a photodetector 4b, a register 11 and a driving circuit 12 at the reception side at the time of waiting and an external signal light of low frequency is received by the photodetector 4b, then a signal processing circuit 6 with large power consumption is made energizable from that point of time. Then a high frequency modulation signal is received by the photodetector 4a and the modulation signal is subject to amplification or demodulation or the like by the signal processing circuit 6, and the resulting signal is outputted from a terminal T2. |
