Method and apparatus for driving a discharge lamp

摘要

A method and apparatus for driving a lamp that uses a DC to AC inverter that is connected to a primary winding of a transformer are disclosed. The inverter frequency is variable, and in one embodiment, may be controlled by a voltage controlled oscillator. Circuitry is included that monitors the phase relationship between a voltage across a primary of the transformer and a current through the primary of the transformer. The circuitry monitors the phase relationship and adjusts the inverter frequency, such as by adjusting voltage controlled oscillator, so that the phase relationship is maintained at a predetermined relationship.