| 摘要 |
PROBLEM TO BE SOLVED: To prevent flash light generated by auxiliary lamp power increase control which is additive when an electrode temperature is high. SOLUTION: In the case where a discharge lamp is relighted at a long time after it is lighted off, charge is not left in a capacitor 313, but a large current flows through a resistance 323 to an operation amplifying circuit element 302, while a transistor 306 gets on to supply a current to a resistance 320 as well. A lamp voltage VL and a lamp current thus become large, and a large lamp power is applied to the discharge lamp. In the meanwhile, in the case where it is relighted at a short time after it is lighted off, charge in corresponding quantity to an off-time is left in the capacitor 313, when the transistor 306 is off without supplying a current to the resistance 320, so the lamp power is small compared to that at the time of cold starting. |
