| 摘要 |
PURPOSE:To obtain an analog light image transmitter which does not affect badly a simultaneously transmitted voice signal even if an excessive signal other than an image signal is inputted. CONSTITUTION:A coupling part 3 performs a frequency division and multiplexing of both the image signal S1 from an image signal input terminal 1 and the frequency modulation signal S3 that a frequency modulator 7 generates in response to the voice signal S2 from a voice signal input terminal 2. A pulse frequency modulation is performed for a frequency division multiplexing signal S4 by a pulse frequency modulator 4, a laser driving circuit 5 generates laser driving output S7 in response to a pulse frequency modulation signal S6, a laser diode 6 generates light signal in response to laser driving output S7 via a switch 9. But, when a large noise is superimposed on the image signal S1, a synchronizing signal detection part 10 generates a synchronizing signal non-detection signal S5 and the switch 9 lets the laser driving output S8 from a laser driving circuit 8 in response to the frequency modulation signal S3 be the driving input of the laser diode 6 when the switch 9 receives this signal S5. |
