| 摘要 |
PURPOSE:To detect the signal interrupting state by using a logical circuit so as to detect the missing of a timing wave due to signal interruption. CONSTITUTION:A timing signal is applied to one input A of an OR circuit 5 and the timing signal via a delay circuit 6 is applied to the other input B. In this case, the delay time of a delay circuit 6 is determined to a half of a period T of the timing signal. Thus, when the timing signal is inputted, a high level signal H is outputted from the OR circuit 5 and an output D of a mean value detecting circuit 7 goes to a high level VH. On the other hand, when no timing signal is inputted and only noise exsits, the output of the OR circuit 5 is not always at high level and the output of the mean value detecting circuit 7 goes to a level VL being remarkably lower than the level VH. Then, in selecting a reference voltage VS suitably, the state of signal interruption is detected accurately. |
