| 摘要 |
PURPOSE:To obtain a power supply synchronizing type timepiece circuit which can produce an alarm tone even under the service interruption, by giving driving control to an alarm tone generator at an alarm set time with use of the output of an oscillating circuit that works during the service interruption by an auxiliary DC power supply. CONSTITUTION:The second pulse produced by a second pulse circuit 15 is applied to a timing circuit via a second pulse selecting circuit 19 while the AC power supply input is applied. When an alarm signal is generated an external device is driven via a buffer circuit 20. When the service interruption arises, a service interruption detecting circuit 16 detects the service interruption. Then a power supply switching circuit 13 supplies the DC output of a backup battery 14 to an oscillating circuit 17, a dividing circuit 18, circuits 19 and 20, an alarm tone gate circuit 22, etc. The circuit 17 produces a pulse of 4,096Hz, and this pulse is selected by the circuit 19 via the circuit 18. Thus the timing is continued. When an alarm signal arises during the service interruption, the output of the circuit 17 is supplied to a speaker 23 via the circuit 23 to produce an alarm tone. At the same time, the external device is driven via the circuit 20. As a result, an alarm tone can be produced even under the survice interruption. |
