| 摘要 |
<p>PURPOSE:To make the steep rise of a current to an incandescent lamp gentle and reduce undesired sound and electric noises by phase-controlling the shift stage from the off-period to the on-period as the chopper period. CONSTITUTION:The action of a switch element 13 is controlled during each half cycle period of AC voltage in the combination of the on-period TON, off- period TOFF, and on/off chopper action period TCHOP. The control is performed in the combination of (TOFF+TCHOP+TON+TCHOP+TOFF) during one half cycle period and symmetrical in the center. The shift front TOFF to TON is made via TCHOP, and the steep rise of the load current at the time of phase control is made gentle. The basic dimming is performed at the ratio of TON and TOFF, and the high-frequency switching loss of the element 13 caused by the chopper action can be reduced. The element 13 is controlled symmetrically in the center, the voltage and current are made in the same phase during dimming like during full lighting, and the loss can be reduced.</p> |
