| 摘要 |
A driver (10) for driving a gas discharge lamp (11), preferably implemented as half-bridge converter, has two states, corresponding to rising lamp current (dI/dt>0) and falling lamp current (dI/dt<0), respectively. A controller (12) always changes state (SS1?SS2; SS2?SS1) at predetermined phases (fs=2/8; fs=6/8) of the lamp current. At other predetermined phases (fs=1/8; fs=3/8; f<SUB>s</SUB>=5/8; f<SUB>s</SUB>=7/8), the controller randomly decides whether or not to change state (SS1?SS2; SS2?SS1), wherein the probability (p) for changing is larger than 0 and lower than 1. As a result, the frequency spectrum of the lamp power is smoothened, the power at individual frequencies being reduced, so that the probability of stimulating acoustic resonances in the lamp are reduced. |
