| 摘要 |
<p>When the phase control is effected on a supply voltage to a load having positive resistance characteristics with respect to temperatures before a current is allowed to pass, a voltage is supplied for a current passing time T1, and the voltage is supplied for a current passing time T2 longer than the current passing time T1, and the voltage is supplied for a current passing time T3 shorter than the current passing time T2. Also, a second control pattern is effected at least once, in which the current is passed while the current passing time is kept substantially constant, then the current passing time is extended before the attenuation rate of the peak value of the resulting load current saturates, and then the current is passed while the extended current passing time is kept substantially constant. Consequently, a voltage drop can be reduced effectively without causing large distortion of the current waveform or large conduction noise by omitting an expensive noise filter or special hardware. <IMAGE></p> |
