| 摘要 |
PURPOSE:To surely turn on a thyristor even under a usual environmental condition, by supplying repeatedly a signal to a gate of the thyristor. CONSTITUTION:A gate signal of a thyristor can be set to an on-state exactly by supplying it not only once but repeatedly. The thyristor being in an on-state is changed to an off-state by inverting the polarity of a power supply voltage which is supplied between an anode and a cathode. Therefore, when a thyristor is brought to an anti-parallel connection so that the gate signal of a high frequency is supplied continuously even at the time point when an AC waveform has become a negative half-wave, the thyristor which has become an off-state at the time point of a positive half-wave becomes an on-state, when the AC waveform has become the negative half-wave. In this case, when the gate signal exceeds a half period of an input AC waveform, and becomes off at the time point within one period, the thyristor which has become on at the time point when one period of the input AC waveform has been ended becomes off.
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