| 摘要 |
PROBLEM TO BE SOLVED: To prevent trouble or the like of a lighting device by the last stage of the service life of a discharge lamp by restarting a switching element, changing operation time of a preheating time setting timer circuit, and switching it to a lighting frequency. SOLUTION: In starting operation of a discharge lamp 11 of a discharge lamp lighting device, when voltage of a capacitor 28 exceeds Zener voltage of a Zener diode 37, a transistor 39 is turned on, and electric charge of capacitors 24 and 31 is discharged through a diode 40. When the voltage of the capacitor 28 exceeds the breakover voltage of a bidirectional trigger diode 30, electric charge of the capacitor 28 is let to move to the base of a transistor 6, and oscillation is started. Accordingly, the transistor 6 repeats on and off in a self-excited manner, and a DC voltage is converted into a high frequency. Even if oscillation of a switching element is stopped by a half-wave discharge phenomenon by dispersion or the like of the discharge lamp at low temperature starting time, it is restarted, and since preheating time of the discharge lamp can be changed, the discharge lamp can be lighted. |
