Title:
【考案の名称】電話回線用センサユニット
Document Type and Number:
Japanese Patent JP2564743
Kind Code:
Y2
Abstract:
A sensor circuit for telephone line (10) includes a detection coil (12a) inserted in a telephone line (14). The coil generates a magnetic flux according to a line current which flows in the telephone line. A magnetic sensor (12b) such as a Hall element generates a voltage signal in response to the magnetic flux. An output of the magnetic sensor is amplified by an amplifier (16). A calling signal detection circuit (18) which receives an output of the amplifier includes a capacitor (20) for cutting-off a direct current component included in the amplified output. An alternating current component is inputted to a (-) input of a hysteresis comparing circuit (22) which receives a reference voltage (Vref1) at a (+) input thereof. Therefore, the alternating current component is converted into a pulse signal which is then withdrawn at an output terminal (34) as a calling signal for ringing a bell of a telephone set. In addition, a line current supervisor circuit (36) is connected to the output of the amplifier so as to detect the line current by utilizing reference voltages (Vref2, Vref3).
Inventors:
Sugiyama Shinsho
Hiroyuki Ohta
Hiroyuki Ohta
Application Number:
JP5055291U
Publication Date:
March 09, 1998
Filing Date:
July 01, 1991
Export Citation:
Assignee:
MURATA MANUFACTURING CO.,LTD.
International Classes:
H04M1/00; H04M19/04; (IPC1-7): H04M1/00
Domestic Patent References:
| JP3153156A |
Attorney, Agent or Firm:
Kazuhide Okada
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