| 摘要 |
PROBLEM TO BE SOLVED: To control the side of a transmitter from the side of a receiver by forming a required modulation control signal on the receiver side, and providing a light emitting means for emitting light corresponding to this signal and a demodulating means for demodulating an electric signal corresponding to received side and demodulating it into original control signal on the transmitter side. SOLUTION: A control signal such as a switching signal for the source of a video signal is inputted to a control signal input terminal 23 of the receiver. This control signal is converted into light by a light emitting element 19 after being amplified through a light emission driving circuit 20 while modulating its frequency through an FM modulator 21, and floods to the transmitter. On the other hand, the electric signal received and converted by a light receiving element 11 of the transmitter is amplified to a prescribed level by a preamplifier 10. After amplification, its frequency is demodulated by a carrier wave used for the FM modulator 21 of the receiver by an FM demodulator 9. The demodulated signal is held in a holding circuit 8 at timing according to a synchronizing signal from a synchronizing detecting circuit 2 and outputted as a control signal from a control signal output terminal 7. |
