| 摘要 |
PROBLEM TO BE SOLVED: To provide an ultra-high pressure discharge lamp with an enclosed amount of mercury of not less than 0.20 mg/mm<SP>3</SP>, with a stabilized position of an arc bright spot, prevented from occurrence of so called flicker. SOLUTION: A power supply device supplies alternating current with a frequency selected from a range of 60 to 1,000 Hz as a stationary frequency to the ultra-high pressure discharge lamp with an enclosed amount of mercury of not less than 0.20 mg/mm<SP>3</SP>. In case a lighting voltage of the discharge lamp is not less than a first prescribed value, a prescribed low frequency lower than the stationary frequency is inserted, and in case a lighting voltage of the discharge lamp becomes lower than a second prescribed value set lower than the first prescribed value, the low frequency is not inserted. COPYRIGHT: (C)2007,JPO&INPIT |
