ELECTRONIC KEY TELEPHONE DEVICE

摘要

PURPOSE:To decrease the number of core wires of a connection cable and to facilitate an easy construction by using just two data transmission lines to transmit calls between key telephones after distributing the transmission data in series in terms of time between a primary device and plural key telephones and also applying a channel led from a trunk line to the channel connected to each key telephone from the primary device. CONSTITUTION:A data transmission line DT which gives the multiple connection to each of (n) units of key telephones 32 is connected to a data transmission circuit 301. While (m) sets of channels SP are connected to a trunk line circuit 303. An end of each of these channels SP has (m) pieces of trunk lines and is connected to a trunk line 310 via a trunk line circuit 303 with the other end having the multiple connection to all key telephones 320. The channel SP and (m+1)X2 pieces of lines DT are connected to each telephone 320 from the terminals of a terminal plate 340. Therefore 4n-2(m+1)=2{(n-m)+(n-1)} pieces of core wires can be reduced compared with 4n pieces of a conventional system for a connection cable 330 between a primary device 300 and (n) units of telephones 320.