| 摘要 |
PROBLEM TO BE SOLVED: To positionally stabilize an arc bright spot and prevent occurrence of flickers in an extra-high-pressure electric discharge lamp having a mercury enclosed amount of 0.20 mg/mm<SP>3</SP>or more during its low electric power lighting time. SOLUTION: To the high-pressure electric discharge lamp 10, alternate electric voltage is supplied from an electric power supply circuit having a step-down chopper circuit 1 and a full bridge circuit 2 to light the lamp. During a steady state lamp lighting time when the lamp is lighted by the electric power of >80% of a rated electric power, the alternate electric current of the steady state lamp lighting frequency of 60-1,000 Hz and the alternate electric current with low frequencies of 5-200 Hz are alternately supplied with a length of a half cycle or more and 5 cycles or less with an interval of 0.01-120 seconds to light the lamp. During a low power lamp lighting time when the lamp is lighted by the electric power of 80% or less of a rated electric power, the alternate current of the low power lamp lighting frequency of 60-1,000 Hz and a direct current are alternately supplied at a direct current supply period within a range of 0.2-5 seconds and at an alternate current lighting with an interval of 1-100 seconds to light the lamp 10. COPYRIGHT: (C)2010,JPO&INPIT |
