| 摘要 |
PROBLEM TO BE SOLVED: To prevent a discharge lamp from being extinguished by causing a large current not exceeding a predetermined range to be input only for a short time to a discharge lamp, in which an inert gas is sealed under atmospheric pressure or less, and to prevent the life of the lamp from being decreased significantly. SOLUTION: A lighting circuit 1 for a discharge lamp 7 with a rated power of 35W is provided with a lighting control means 5 which lights the discharge lamp 7 according to the source voltage of a power source 2 and a power control means 8 which controls the power supply during the process of transition from the start of the discharge lamp 7 to a steady state, in accordance with the lamp voltage or lamp current of the discharge lamp 7 or equivalent signals, and which performs constant-power control of the discharge lamp 7 at the rated power. An arc growth control means 9 which issues to the power control means 8 orders regarding power control for developing and maintaining an arc is provided, so that a current with an effective current value of 1.75 to 3.5 amperes is controlled to flow through the discharge lamp 7 for 20 to 200 milliseconds immediately after the transition from a glow discharge to an arc discharge. |
