Abstract: Irrespective of the distance of a line through which a video signal is taken by the camera of a main entrance station, a satisfactory image having not deterioration but excellent visibility is displayed in a monitor of a residential master station. A distance decision unit of a residential master station for displaying a video signal taken by a camera of an main entrance station in a monitor decides the distance of the line length of a master station line in terms of the voltage drop of the DC power supply fed from a controller to the residential master station. A level compensation unit of the residential master station compensates the level of the video signal in accordance with the decided distance. A distance decision unit of the main entrance station decides the distance of the line length of an entrance line in terms of the voltage drop of the DC power supply fed from the controller to the main entrance station.

Abstract: The respective sections between a power source unit 4 and a room master station 1, between the room master station 1 and an entrance door station 2, and between the entrance door station 2 and an electric lock 3 are connected by transmission lines of two-wire system 6 for transmitting signals and electric power.

Abstract: 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.

Abstract: An intercom apparatus has a main line connecting intercom master stations in respective residential rooms. Each master station has a terminal unit which is separate from and removable from the master station, so that the terminal unit can be removed according to need while keeping the connection. The intercom apparatus further has an entrance substation by which the master stations in residential rooms may be called from the entrance substation through the main line for bilateral communication. The terminal unit has terminals for connecting with intercom master stations by a station-to-station spanning wiring forming the main line and a terminal board on which the terminals are mounted for electrical connection with the main line path. A mounting bracket, by which the terminal unit is detachably mounted, is provided in a space which is formed in the backside of the intercom master station.

Abstract: A television door intercom apparatus improves recognition performance for a resident inside a house to recognize a visitor conducting a call operation at the entrance and security in responding to the call. A call detection circuit 31 of a residential master station 2 detects a call when a visitor pushes a call button 11 of a door intercom substation 1, activates a signal generator circuit 32 and causes a master station speaker 39 to output a call sound so that a communication can be exchanged between a substation microphone 16 and a substation speaker 17 of the door intercom substation and a master station microphone 38 and the master station speaker of the residential master station.

Abstract: The invention makes it possible to call a resident of collective housing even when the apartment number of the resident is unknown. A collective housing entrance substation is connected to residential master stations through a controller, and a name retrieval module is connected to the controller. The name retrieval module has a memory in which a name and/or apartment number of a resident is registered in advance, a button operable to display the name and/or apartment number of the resident registered in advance, a name indicator for display of the name and/or apartment number of the resident registered in advance, and a call button that is operated with display of the proper name and/or apartment number to call the residential master station of the resident.

Abstract: An intercom system for a building or apartment house includes at least one main entrance station 1 which is installed at an entrance or the like of a building or an apartment house, a plurality of residential master stations 2 which are respectively installed inside a plurality of residences in the building or apartment house for receiving calls and talking with the main entrance station 1, a common line 3 which connects the main entrance station 1 and respective residential master stations 2 in parallel, a line power supply 4 which supplies direct current power, for example, DC 24 V to the main entrance station 1 and respective residential master stations 2 through the common line 3, an electronic door lock 5 which is connected to the main entrance station 1 for locking and releasing an entrance door of a main entrance, and a plurality of call switches 6 connected to respective residential master stations 2 and mounted on front doors of respective residences for operation by a visitor.

Abstract: An intercom apparatus in which a connection of intercom master stations in respective residential rooms is carried out by use of a terminal unit which is separated from the master station and the terminal unit can be removed according to need with keeping the connecting state.

Abstract: The invention makes it possible to call a resident of collective housing even when a room number of the resident is unknown. A collective housing entrance substation is connected to residential master stations through a controller thereof, and a name retrieval module is connected to the controller, the name retrieval module having a memory in which a name and/or room number of a resident is registered in advance, a button operated to display the name and/or room number of the resident registered in advance, a name indicator for displaying the name and/or room number of the resident registered in advance, and a call button that is operated with the name and/or room number of the resident registered in advance displayed to call the residential master station of the resident.

Abstract: 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.