| 摘要 |
PURPOSE:To enhance the safety and to improve the conversion efficiency by controlling to oscillate by the primary high voltage power source immediately after the power source is turned ON, and then controlling by the secondary DC power source of low voltage. CONSTITUTION:A power source turns ON and OFF the primary DC power source of relatively high voltage by a photoswitching element 8 fed through an input switch 2 and a high frequency transformer 10, rectifies by a rectifier 11 the secondary side voltage of the transformer 10, smoothes by smoothing capacitors 12, 13 to output a DC voltage E2 to a load 14. In this case, the element 8 is controlled to be driven by a high frequency signal through a transistor drive IC5 and a diode 7 from the power source 1 for a charging time determined by a capacitor 6 and a resistor 3 immediately after the switch 2 is closed. Further, after the prescribed time from when the secondary side voltage of the transformer 10 is obtained, a transistor 20 is driven by a high frequency signal of the IC18 on the basis of the difference between the desired output voltage and the actual output voltage E2 to control ON and OFF the element 8 through a light emitting diode 9. |
