| 摘要 |
PROBLEM TO BE SOLVED: To provide a telephone set which suppresses call troubles caused by switching a voice input means. SOLUTION: The telephone set can be connected to a handset and a headset. It comprises: a first OP amplifier for amplifying a voice signal, where a first wiring for transmitting a voice signal to either the handset or the headset, and a second wiring for matching reference potentials are connected in parallel; a second OP amplifier connected to the other of the handset or the headset for amplifying the voice signal; a first switch provided between a power source and the first OP amplifier to supply a supply voltage to the first OP amplifier when receiving a ON signal and to stop supply of the supply voltage to the first OP amplifier when receiving an OFF signal; and a control part which monitors a voltage at an arbitrary point on a third wiring for connecting a first resistance connected to the power source and the first wiring, transmits an ON signal to the first switch if the voltage exceeds a predetermined value and transmits an OFF signal if the voltage does not exceed the predetermined potential. COPYRIGHT: (C)2008,JPO&INPIT
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