| 摘要 |
A television intercom system need not prepare two kinds of electric power source adaptors even when it is equipped with an expanded monitor master station, and need not either use an electric power source adaptor having a large capacity. In the television intercom system, a picture bus controller supplies electric power sources to a camera-equipped entrance substation, a monitor master station and an expanded monitor master station, and a picture picked up by the camera-equipped entrance substation is displayed on the monitor master station and the expanded monitor master station. The picture bus controller includes an electric power source expansion sub-adaptor that is the same as an electric power source main adaptor used before expansion when the expanded monitor master station is added, an electric power source detection circuit for detecting the electric power source expansion sub-adaptor, and an electric power source switching circuit for dividedly supplying the electric power source from the electric power source main adaptor used before expansion and from the electric power source expansion sub-adaptor to the picture bus controller, the camera-equipped entrance substation, the monitor master station and the expanded monitor master station.
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