| 摘要 |
A gas discharge lamp electronic ballast circuit including a gas discharge lamp (51); a rectifier circuit (11a, 11b, 11c, 11d, 13) responsive to CA power for providing a full wave rectified sinewave voltage across output terminals of the rectifier circuit; a transformer (T1) having a primary winding and a secondary winding; a switching circuit (29) for repetitively connecting the rectifying circuit full wave rectified sinewave voltage to the primary winding; a driving circuit (33, 35, 37, T2, 49) responsive to the secondary winding for driving the lamp with a sinusoidal voltage having a predetermined frequency; a current sensing circuit (39, 41, 45, 47, 43) for sensing an average of peaks of current flowing in the driving circuit; and a pulse width modulation circuit (25) responsive to the full wave rectified sinewave voltage and the current sensing means for pulse width modulating the switching circuit at the predetermined frequency such that the rectifier circuit provides a current having a flattened full wave rectified sinewave waveform.
|
