| 摘要 |
PURPOSE:To attain a high power factor, miniaturization at a low cost. CONSTITUTION:In a power supply circuit for a discharge lamp which generates a dark angle eliminating voltage to be inputted to a high-frequency circuit, a construction made up of a series circuit of a capacitor Co and a diode Do inserted in parallel into a rectifier circuit 10, a switching means for impressing a pulsating current on the capacitor Co from the rectifier circuit 10 and a control circuit 20 for turning the switching means ON and OFF so that a voltage of the capacitor Co be kept fixed at about half of the maximum value of the pulsating current outputted by the rectifier circuit 10, is provided. Moreover, the control circuit 20 has, in its construction, a comparing means 22 which compares a capacitor voltage with a reference voltage and outputs a control signal Sc for turning the switching means ON and OFF. |
