| 摘要 |
PURPOSE:To set easily various ringing tones through simple constitution with a telephone device containing a tone dial signal producing circuit, by using the signal outputted from the tone dial signal producing circuit as a call signal. CONSTITUTION:A tone dial signal producing circuit 30 divides the output of a reference oscillator having an oscillation frequency of about 3.5MHz in a division ratio corresponding to an indication signal based on the ten-key input. This division output is converted into an analog form from a digital form via a counter, a ladder resistance circuit network, etc. Finally, two types of frequency signals are combined and delivered in the form of a tone dial signal. For instance, a handset is picked up to give an external call through a telephone from a master station and a telephone switch S2 is operated. Thus an indication signal for closure of a switch 14 is outputted from a control circuit 28. Then ten- key 29 is operated for dialing. Thus the tone dial signals corresponding to the operated numeric characters are outputted from the circuit 30 and sent to an external telephone circuit via the switch 14. |
