JPS63142975U

JPS63142975U -

Info

Publication number: JPS63142975U
Application number: JP3548387U
Authority: JP
Priority date: 1987-03-11
Filing date: 1987-03-11
Publication date: 1988-09-20

Description

[Brief explanation of the drawing]

第１図は本発明の一実施例に係る局線インター
フエイス回路の構成回路図、第２図は検出回路７
１の回路図、第３図は局着信号と検出回路７１の
出力電圧との関係を示す図、第４図はボタン電話
システムの構成ブロツク図、第５図は従来の局線
インターフエイス回路の回路図である。１ａ，１ｂ……ボタン電話機、５，７……巨線
、２９ａ，２９ｂ……局線インターフエイス回路
、６７……直流ループ通過回路、７１……検出回
路、７３……微小電流通過回路、７５……局着信
号通過回路。 FIG. 1 is a configuration circuit diagram of a station line interface circuit according to an embodiment of the present invention, and FIG. 2 is a detection circuit 7.
1 is a circuit diagram, FIG. 3 is a diagram showing the relationship between the station-arriving signal and the output voltage of the detection circuit 71, FIG. 4 is a block diagram of the configuration of a button telephone system, and FIG. It is a circuit diagram. 1a, 1b...Button telephone, 5,7...Big wire, 29a, 29b...Station line interface circuit, 67...DC loop passing circuit, 71...Detection circuit, 73...Minimum current passing circuit, 75 ... Station-arriving signal passing circuit.

Claims

[Scope of Claim for Utility Model Registration] In a central office line interface circuit that interfaces a central office line and a key telephone, a DC loop passing through which forms a closed loop with the central office line when making a call and causes a DC loop current to flow within this loop. A circuit, a station-arriving signal passing circuit that passes the station-arriving signal when a call is received from the station line, and a detection circuit that detects the DC loop current, the station-arriving signal, and the polarity inversion signal of the station line. central office line interface circuit.