| 摘要 |
PROBLEM TO BE SOLVED: To provide a television receiver attached interphone system for multiple dwelling houses wherein the number of wired transmission lines is reduced without losing the transmission quality between a shared part apparatus and a house unit. SOLUTION: The shared part apparatus 1 deposited to a shared entrance of multiple dwelling houses is connected to a plurality of the house units 2 each located to each house of the multiple dwelling houses via the transmission line. The transmission line includes a trunk line L1 connected to the shared part apparatus 1 and house dependent lines L2 connected to each house unit 2, and a branch 3 is respectively interposed to a connection part between the trunk line L1 and each house dependent line L2. The trunk line L1 and each house dependent line L2 comprise a control line Lc for transmitting a control signal, and a shared line Ld for transmitting a signal resulting from frequency-multiplexing a voice signal and a video signal. The branch 3 is provided with a path changeover switch 31 inserted to the shared line Ld, and when the house unit 2 selected by the shared part apparatus 1 applies a DC voltage to a slave unit connection line L3 connected to a doorphone slave unit 5, the path changeover switch 31 connects the trunk line L1 to the house dependent line L2. COPYRIGHT: (C)2004,JPO&NCIPI
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