| 摘要 |
PROBLEM TO BE SOLVED: To quickly stabilize output light in starting a discharge lamp and to suppress fluctuations due to overshooting and undershooting. SOLUTION: Lamp voltage is detected by a lamp voltage detecting circuit 1 in starting a discharge lamp and lamp current is controlled first by an activation lamp current control circuit 4 according to the detected lamp voltage. Then the lamp current is dropped during the prescribed period of time with the prescribed drop characteristic by an activation lamp current dropping timer control circuit 5, from the time of applying the maximum power to the discharge lamp, or form the time when the lamp voltage gets up to the preset voltage corresponding to the lamp voltage detected immediately after activation. After that, the lamp current is delayed and lowered to the rated current by a stable time lamp current control circuit 3. |
