| 摘要 |
PURPOSE: To prevent the blackening phenomenon of a discharge lamp and extend its service life by limiting the amount of current passed through the discharge lamp by a capacitor after the discharge lamp is lighted when generating a high voltage needed for lighting of the discharge lamp by employing a transformer. CONSTITUTION: When power is supplied to a power source terminal Vcc and the period of time constant of a charge part 1 elapses, a second switching part 3 is turned ON to initiate current hoop of a resonance part 4 and the interaction of a first switching part 2 and the second switching part 3 with the resonance part 4 causes resonance in a predetermined cycle. Then, the current passed through a primary winding T110 of a step-up transformer T100 alternately flows forward and backward in the predetermined cycle, and the voltage is induced and elevated in the secondary winding T120 of the transformer T100. Then, a preheating power source is placed through the secondary winding T120 before the discharge of discharge lamps LP11 and LP12 is initiated, and a power source of the winding T110 is placed on filaments of the discharge lamps LP11 and LP12 to conduct a discharge current through a capacitor and to generate light during discharge. |
