| 摘要 |
PROBLEM TO BE SOLVED: To provide a communication apparatus capable of detecting a call signal without delay even when the head of a ringing signal is displaced toward a negative polarity side, and preventing a telephone set from ringing despite non-ring function validated. SOLUTION: When the LINE voltage of a telephone line 120 is detected to be displaced toward the negative polarity side, a half-wave photo-coupler 108 outputs a CI2 signal indicating the detection of the ringing signal to a power source control CPU 110. Then, when the non-ring function is set to validation, the power source control CPU 110 outputs an SON2 signal to an S relay 106 with the CI2 signal as a trigger. The S relay 106 which receives the SON2 signal is changed from an off-state (a state where a connection line is brought into contact) into an on-state (a state where the connection line is separated). Consequently, a circumscribed telephone 430 is separated from the telephone line 120, thereby attaining non-ringing. COPYRIGHT: (C)2009,JPO&INPIT
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