Key telephone equipment and associated method

Details Key telephone equipment and associated method Key telephone equipment and associated method

1983-01-03

1985-08-20

George, Keith E.

179 18AD, 179 99A, H04M 160, H04M 906

Patent

active

045366152

ABSTRACT:
Telephone apparatus including a main unit and a plurality of loudspeaker type key telephone sets, in which a pair of office line call wires to be used solely for an office line call, a pair of audio signal wires to be used for calling and talking with a loudspeaker and a pair of data wires to be used for time-sharing transmission of control data extend from the main unit. The respective loudspeaker key telephone sets all connect in parallel to these three pairs of wires. A neutral potential point of the audio signal wire pair and a neutral potential point of the data wire pair are coupled, on the main unit side, to a D.C. power supply via a D.C. network and to loudspeaker drive systems connected to the audio signal wire pair via an A.C. network. The neutral potential points on the button-switch telephone set side connect to a D.C. constant voltage circuit in each telephone set via a D.C. network and to a talking network in the telephone set via a transfer switch. Thereby the connecting path employing the audio signal wire pair as one conductor and the data wire pair as the other conductor can be used for supplying D.C. electric power to the respective telephone sets and for effecting an extension line call whereby the number of wires connecting the respective telephone sets to the main unit can be minimized to six.

REFERENCES:
patent: 4184054 (1980-01-01), Shibata et al.
patent: 4203011 (1980-05-01), Coviello
patent: 4254306 (1981-03-01), Sekiguchi et al.
patent: 4347409 (1982-08-01), Ogawa et al.

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