| 摘要 |
PURPOSE:To prevent a state that both separately-exited and self-excited switching elements are made ON concurrently by setting the ratio of a switching frequency to a resonator frequency larger than 1.1 in an inverter for a discharge lamp having both the elements. CONSTITUTION:A transistors Q1 is ON/OFF-controlled in separate excitation by a controller 1, and the primary winding of a drive transformer T1 is connected to a load circuit having a discharge lamp la, capacitors C0, C1 to form a resonance circuit. A transistor Q2 is ON/OFF-controlled in self-excitation by a voltage induced in the secondary winding. The transistor Q2 is made conductive immediately before the transistor Q1 is turned OFF when the ON period of the transistor Q1 is increased to increase a current to be supplied to the lamp la. Therefore the ON period of the transistor Q1 by the controller 1 is so set that the ratio of the switching frequency f1 to a resonance frequency f0 becomes larger than 1.1. |
