High efficiency driver apparatus for driving a cold cathode fluorescent lamp

Abstract

An inverter circuit for a gas discharge lamp having a primary circuit having a DC voltage supply, a transformer, a switching circuit including a first switch and a second switch for controlling a conduction state of the inverter circuit; a tank circuit having a resonant inductor and a resonant capacitor, the lamp load being coupled with the resonant capacitor; and a capacitor coupled to the first and second switches for maintaining a voltage across a primary winding of said transformer. Accordingly, the required turns ratio of the transformer is reduced by half which reduces the power loss in the transformer, thereby improving circuit efficiency. In addition, energy stored in a leakage inductance, which is otherwise dissipated across the switches of the push-pull switch configuration in the prior art, is recovered or captured by the clamping capacitor, thereby preventing the occurrence of voltage spikes across the switches.