| 摘要 |
PURPOSE:To enhance surely a calling function even when a telephone set is used in a surrounding where sound is not listened to clearly by generating a bell tone (one ringer tone) and a voice synthesis tone. CONSTITUTION:A call signal from a telephone line is normally an intermission signal and since a tone ringer circuit 2 is actuated synchronously with the call signal, the circuit 2 does not issue ringing while no call signal exists. On the other hand, since a detection circuit 3 outputs a prescribed voltage only during the incoming of the call signal, when the call signal comes to a pause, the output voltage of the detection circuit 3 changes from a high level to a low level. A voice synthesis circuit 4 is started when the output voltage of the detection circuit 3 changes from a high level to a low level, and generates a voice synthesis signal over a prescribed time. The sound synthesis signal and the output signal of the tone ringer circuit 2 are converted into an audible tone through a sounding body 5.
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