| 摘要 |
PROBLEM TO BE SOLVED: To maintain a lighting state of a discharge lamp, or to assure transition to a relighting operation by taking measures for preventing a drive frequency for a switching element which constitutes a DC-AC conversion circuit using series resonance from not continuing to be lower than a resonant frequency. SOLUTION: This discharge lamp lighting circuit 1 provided with the DC-AC conversion circuit 3, a bootstrap circuit 4, a control means 6 for power control has a plurality of switching elements 5H, 5L driven by the control means 6 and series LC resonance circuits (7p, 8, 9). The drive frequency of the switching elements are set higher than a resonant frequency Fon to perform drive control of the switching element in lighting the discharge lamp, and if it is detected that the drive frequency is low and the discharge lamp is turned out, the drive frequency is shifted to a frequency-domain fa2 higher than Foff to restart. And, if the drive frequency is lower than Fon during lighting of the discharge lamp, the drive frequency is returned to a frequency domain fb higher than Fon. COPYRIGHT: (C)2007,JPO&INPIT |
