| 摘要 |
PURPOSE:To reduce the switching loss by bypassing a base current while the voltage between the collector and the emitter of a main transistor crosses zero after the voltage of a base returning winding is inverted to positive. CONSTITUTION:A transistor 51 is connected to the base of a main transistor 32 of a base feedback 1-transistor type blocking inverter 3 for firing a discharge lamp 4, the output of a base feedback winding 31b is differentiated by a capacitor 53, applied to the base of the transistor 51, the transistor 51 is turned ON while the voltage between the collector and the emitter crosses zero immediately before the base current is supplied to the transistor 32, thereby bypassing the base current of the transistor 32. Accordingly, before crossing zero, the transistor 32 is prevented from being turned ON to reduce the switching loss, thereby improving the circuit efficiency. |
