| 摘要 |
PURPOSE:To obtain a highly reliable detecting device practically free from false operarion due to overlapping noises, by delivering an input subjected to full-wave rectification and having a level higher than the prescribed through the intermediary of a timer having an operating time longer than the pulse lenght of noises without being affected by the noises. CONSTITUTION:A signal V2 corresponding to an AC input subjected to fullwave rectification and having a level higher than the prescribed is inputted, via an inverter 5, to a switching circuit 7-1 connected to a diode 8-1 and having a transistor Tr 1, on one hand, and to a switching circuit 7-2 constituted in the same way as the circuit 7-1 and connected with a reversely-polarized diode 8-2, via a timer having an operating time longer than the pulse lenght of noises, on the other. Owing to this timer 6, an output VST2 which is to have a high level in accordance with the signal V2 from the circuit 7-2 is detected, as a discharge voltage of a capacitor 9, by a level detection circuit 10 and a timer circuit 4 corresponding to a half cycle of an input signal, without being affected by noises even when a crack is generated thereby in the signal V2. Accordingly, a highly reliable detecting device practically free from false operation due to overlapping noises. |
