Patent ID: 8330877

Claim:
A self-excited inverter comprising: a pair of switching devices; and a transformer having a primary side to which said switching devices are connected and a secondary side to which a lamp is connected, said transformer including a pair of main windings and a drive winding disposed on the primary side, said switching devices being connected to said individual main windings; wherein a pulse voltage is applied alternately to gates of said individual switching devices through said drive winding, causing said switching devices to turn on and off in alternate turns to produce an AC voltage supplied from said main windings to the secondary side of said transformer; wherein a startup voltage applied to the gates of said pair of switching devices is controlled to follow an input voltage supplied to said main windings of said transformer, wherein the pulse voltage is controlled to follow the input voltage, and wherein the self-excited inverter is configured so that the startup voltage and the pulse voltage both drop in response to a drop in the input voltage.