| 摘要 |
PROBLEM TO BE SOLVED: To allow a light flux to rise quickly and minimize the overshoot or undershoot by controlling the lamp impression power while transition is made after the lighting is started from the first control region bit by bit till the fourth control region. SOLUTION: When a switch 2 is turned on, a lamp power supply means 100 is actuated to impress a voltage VL on a discharge lamp 3, and also an ignitor circuit 300 is actuated to generate a high voltage in a coil 4, which is impressed on the lamp 3. Between the electrodes of the lamp 3 a dielectric destruction is produced to result in break-down and the electric charges on a capacitor 105 are discharged as the lamp current IL through the lamp 3, and thus the lamp 3 starts lighting up. Then the ignitor circuit 300 stops operating, and the coil 4 is controlled so that generation of high voltage is stopped. By a power control means 500 the lamp current is approximated with the time constant curve so that the light flux is given an ideal rising characteristic, and thereby the overshoot or undershoot is minimized. |
