| 摘要 |
PURPOSE:To detect not only the case where the period of fundamental clocks is abnormally longer than a regular period but also the case where it is abnormally shorter, by providing the first pulse oscillator, the second pulse oscillator, and an abnormality detecting (time comparing) circuit. CONSTITUTION:The first pulse oscillator 2 oscillates the first pulses having a pulse width T1 which is longer than the pulse width or a half period T0 of fundamental clocks CP0 and is shoter than one period 2T0. The second pulse oscillator 3 oscillates the second pulses CP2 having a pulse width T2 shoter than the pulse width or the half period T0 of fundamental clocks CP0. Then, time relations 0<T2<T0<T1<2T0 are satisfied when fundamental clocks CP0 are in the normal oscillation state. Consequently, these time relations are monitored by an abnormality detecting (time comparing) circuit 4 to detect not only the case where the period of fundamental clocks CP0 is abnormally longer than the reqular period but also the case where it is abnormally shorter. |
