| 摘要 |
PURPOSE:To obtain the high-accuracy device which does not generate a clocking error even if there is a service interruption or restoration in a commercial power supply by synchronizing, by a synchronizing means, a 2nd clocking means with a 1st clocking means during the period when the commercial power supply is impressed and to synchronize a 1st clocking means which does not clock during the service interruption with the 2nd clocking means at the time when the service is restored after the interruption. CONSTITUTION:The 1st, 2nd clocking circuits 20, 21 respectively execute clocking by the output of a 1st oscillation circuit 6 synchronize with the commercial frequency from a commercial power supply circuit 10 and the output of the 2nd oscillation circuit 9 based on the self-oscillation frequency. A central processing circuit 22 judges whether the service is interrupted or not in accordance with the output of a service interruption detecting circuit 10. The circuit 21 is corrected in the specified period and is synchronized with the circuit 20 on the basis of the circuit 20 when the voltage from the circuit 100 is impressed. The circuit 20 stops and the circuit 21 continues clocking and is changed over to the reference when the service is interrupted. The circuit 20 restarts clocking when the service is restored from the interrupted state. The circuit 22 is simultaneously corrected to and synchronized with the clocking of the circuit 21 and is then used as the reference circuit. |
