Patent ID: 6333606
Filing Date: 2001-12-25
Classification: H05B

Abstract:
A ballast for discharge lamp, the ballast for discharge lamp for utilizing high frequency voltage generated by alternatively switching two switching elements to light the discharge lamp, the ballast comprising:a primary winding of a switching transformer to which the high frequency voltage is applied;a secondary winding of a switching transformer for alternatively switching the two switching elements according to reverse electromotive voltage generated by application of high frequency voltage to the primary winding; andstabilizing means for stabilizing reverse electromotive voltage generating at the secondary winding, the stabilizing means comprises:a control winding where reverse electromotive voltage is generated according to high frequency voltage applied to the primary winding;a diode for half-rectifying the reverse electromotive voltage generated at the winding for control;charging/discharging circuit for receiving the reverse electromotive voltage half-rectified by the diode to charge and discharge according to charging/discharging time constant; anda transistor for switching according to a voltage value of the charge/discharge circuit to control reverse electromotive voltage generated at the secondary winding.