Patent ID: 6894437

Claim:
Light source device, comprising: a discharge lamp (Ld) having a pair of opposed electrodes (E 1 ,E 2 ); and a feed device (Ex) connected to the electrodes for starting said discharge lamp and for supplying a discharge current to said electrodes, and including a ballast circuit (Bx), wherein the ballast circuit (Bx) comprises, at a feed control circuit (Fx) detecting a lamp current (IL) and/or a lamp voltage (VL). a switching device (Qx), a gate driver signal generation circuit (Upm), and a gate drive circuit (Gx) wherein an output (St) of said feed control circuit (Fx) being provided such that that the switching device (Qx) is controlled through the gate driver signal generation circuit (Upm) and the gate driver circuit (Gx), and wherein the output (St) of said feed control circuit (Fx) undergoes a PWM-modulation via a gate modulation circuit (Uw) of the gate driver signal generation circuit (Upm), and produces a gate driver signal (Sg) at the same time by receiving a phase modulation signal (Sm) of a phase modulation control circuit (Ut).