| 摘要 |
PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device smoothly changing the light output of a discharge lamp and reducing the stress applied to the constituting elements of an inverter circuit. SOLUTION: An inverter circuit 2 converts the output of a DC power source 4 into an AC voltage with a switching element and feeds it to a discharge lamp La. A control circuit 3 sets the operating frequency of the inverter circuit 2 to the prescribed preheating frequency to preheat the discharge lamp La, then changes the operating frequency of the inverter circuit 2, to the prescribed starting frequency lower than the preheating frequency, and applies the starting voltage capable of lighting the discharge lamp La to the discharge lamp La. When a lighting detecting circuit 5 detects that the discharge lamp La is lighted, the control circuit 3 instantaneously changes the operating frequency of the inverter circuit 2 from the starting frequency to a first frequency which is higher than the starting frequency and lighting frequency and lower than the maximum value of the frequency capable of maintaining the lighting state of the discharge lamp La then gradually changes the operating frequency from the first frequency to the prescribed lighting frequency. |
