| 摘要 |
PROBLEM TO BE SOLVED: To avoid the passage of a resonant frequency FO and eliminate adverse effects on severe loads of elements. SOLUTION: A frequency detecting circuit 90 detects a lighting frequency F and a tube voltage detecting circuit 80 detects abnormal voltages at the time of an end stage of a service life of a discharge lamp 34 and at the time of removing of the discharge lamp 34. A frequency control circuit 70 performs a control to change a shift direction of the frequency in response to the lighting frequency F. Accordingly, the passage of the resonant frequency FO is avoided and the adverse effects on the severe loads of each element are eliminated. COPYRIGHT: (C)2004,JPO&NCIPI |
