| 摘要 |
PURPOSE: To obtain a power supply, a discharge lamp lighting unit and a lighting fixture in which distortion of input current is suppressed with a high power factor while suppressing ripples on the output voltage. CONSTITUTION: First and second switching units 5, 6, being turned ON/OFF alternately, are connected between the output terminals of a rectifier 4 and a first capacitor 7, performing the smoothing function for the output frequency of the rectifier, is connected in parallel with the first switching unit. A load circuit 8 includes an inductor 9 and a load 10 wherein the equivalent series reactance Xe and resistance Re are set such that Xe/Re>=1.7. In response to turn ON/OFF of the pair of switching units, the inductor and a second capacitor 12 form a resonance circuit. The resonance voltage functions to feed a charging current from the rectifier to the first capacitor thus realizing high input power factor and low distortion of input current. |
