| 摘要 |
955,569. Intercommunication systems. STANDARD TELEPHONES & CABLES Ltd. Sept. 1, 1961 [Sept. 2, 1960], No. 31547/61. Heading H4K. Each station is on a separate line comprising a signalling branch and a communication branch, a plurality of switch means at each station normally connecting the signalling branch of the associated line individually to the signalling branch of each of the other lines; selective operation of some of the switch means, such as S31, S31A, and L313, transfers a selected one of these connections from the signalling branch of the associated line to the communication branch thereof so as to connect this communication branch to the signalling branch of a selected line, enabling a call signal to be sent from a calling station to the station associated with the selected line (such as a spoken announcement sent from transducer SW31 to transducer SW33), and means (such as rectifiers G31, G31A &c.) are provided to prevent this call signal from being passed on to the signalling branches of the other lines which are normally connected to the signalling branch of the selected line. Battery is extended from the calling station to reduce the forward resistance of rectifier G33 at the called station but not of the corresponding rectifiers such as G32 at other stations. The two-way speech circuit is completed by operation of switches S33, S33A, and L331 at the called station SW33. |
