发明名称 |
Sensor circuit for telephone line |
摘要 |
A sensor circuit for telephone line includes a detection coil (52) inserted in a telephone line (22). The coil generates a magnetic flux according to a line current which flows in the telephone line. A magnetic sensor (54) such as a Hall element generates a voltage signal in response to the magnetic flux. An output of the magnetic sensor is applied to a comparing circuit (58) and a tone deriving circuit (60) via an amplifier (56). The comparing circuit includes two comparators one of which compares the voltage signal from the magnetic sensor with a first reference voltage (V1) and the other of which compares the output signal with a second reference voltage (V2), so that a line current supervisory signal is outputted from the comparing circuit. The tone deriving circuit includes a band-pass filter and derives a tone signal from the voltage signal of the magnetic sensor. The line current supervisory signal and the tone signal are applied from terminals (46, 48, 62) to a signal processing circuit (36) by which a facsimile or a telephone set is selectively enabled.
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申请公布号 |
US5311587(A) |
申请公布日期 |
1994.05.10 |
申请号 |
US19920898086 |
申请日期 |
1992.06.12 |
申请人 |
MURATA MANUFACTURING CO., LTD. |
发明人 |
OHTA, HIROYUKI;SUGIYAMA, MASAAKI |
分类号 |
H04M1/82;(IPC1-7):H04M1/00 |
主分类号 |
H04M1/82 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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