| 摘要 |
PROBLEM TO BE SOLVED: To provide a video doorphone system for multiple dwelling house that simplifies its installation. SOLUTION: This invention provides the video doorphone system for multiple dwelling house where an integrated entrance unit 1 having a camera 1a, a speech circuit 1b, and a channel selection circuit 1c is connected to a living room interphone 4 and a living room monitor unit 5 having an FM signal amplifier circuit 5a, an FM demodulation circuit 5b, a monitor 5c, and a power supply circuit 5d energized by a monitor power supply under the control of the living room interphone through an interphone control unit 2 having a control circuit 2a and a speech control circuit 2b, a video control unit 3 having a monitor power supply 3b and an FM modulation circuit 3a by way of a speech/control trunk line 7 and a video signal trunk line 6 that respectively transmit a speech/ control signal and a video signal, and the living room monitor unit has a switch means 5f that supplies independent power from other power supply 8 to the FM signal amplifier circuit and a new video signal branch trunk line 9 from which a superimposed signal between an output signal from the FM signal amplifier circuit and a DC voltage from the independent power supply is outputted is provided.
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