| 摘要 |
<p>PURPOSE:To prevent securely the misreading of digital input data which occurs in the event of an instantaneous power failure by inputting an AC supply voltage to a comparator and latching input data by its output signal. CONSTITUTION:A voltage with a full-wave rectified waveform is outputted from an AC power source 15 through a transformer 18 and a diode bridge 19, and a timing pulse A is sent out as the output signal of the comparator 17 when the rectified waveform almost has a peak value. If an instantaneous power failure occurs in the power source 15 at a point B of time, the negative-side input terminal of the comparator 17 is at 0V and the voltage holding time of the positive input terminal is held longer than a specific time in a DC rectifying power source, so a positive voltage is applied throughout the instantaneous power failure. Consequently, the generation and transmission of an erroneous signal are prevented in the period of this instantaneous power failure.</p> |
