| 摘要 |
PURPOSE: To provide a high pressure discharge lamp lighting device having excellent starting ability at a low cost by continuously turning on a three-terminal alternating current control element during the predetermined time so that the peak value of the voltage of both terminals of a capacitor at the time when the three-terminal alternating current control element is turned off and the OFF-voltage of the three-terminal alternating current control element respectively become the maximum rated value or less. CONSTITUTION: When a high pressure discharge lamp DL is not lighted, a lighting judging circuit 3 outputs 'H', and the 'H' is input to the forth pin of a timer circuit IC1 . In this condition, a control circuit 2 is driven by the direct current voltage from a control power source circuit 1, and the trigger signal at the redetermined voltage is applied to a second pin of the IC1 . A pulse at the time width, which is decided by a resistor R10 and a capacitor C5 , is output from the third pin, and the three- terminal alternating current control element Q1 is turned on during the predetermined time. When the element Q1 is tuned on, the oscillating current flows in a closed loop of a commercial alternating current power source VS, a primary coil N1 of an inductor L1 , the capacitor C1 , and the element Q1 so as to start the discharge lamp DL. Consequently, during the predetermined time, turn-off of the three-terminal alternating current control element Q1 is eliminated so as to improve the starting ability. |
