Patent ID: 7079175

Claim:
A television intercom system for respectively supplying electric power sources by a picture bus controller to a camera-equipped entrance substation, a monitor master station and an expanded monitor master station and displaying a picture picked up by said camera-equipped entrance substation on said monitor master station and on said expanded monitor master station, wherein said 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, to add said expanded monitor master station, an electric power source detection circuit for detecting said electric power source expansion sub-adaptor, and an electric power source switching circuit for dividedly supplying the electric power source from said electric power source main adaptor used before expansion and from said electric power source expansion sub-adaptor to said picture bus controller, said camera-equipped entrance substation, said monitor master station and said expanded monitor master station when said electric power source detection circuit detects said electric power source expansion sub-adaptor.