Patent ID: 6479949
Filing Date: 2002-11-12
Classification: H05B,Y02B

Abstract:
An electronic ballast for igniting and maintaining a discharge arc in a light emitting discharge tube, a resistance of the discharge tube varying with a temperature of the discharge tube during operation, the ballast comprising:ballast circuitry including an oscillating inverter circuit for driving an LC tank network coupled to the discharge tube, the LC tank network applying a time varying voltage to the discharge tube, a peak-to-peak magnitude of the time varying voltage applied by the LC tank network being determined by a frequency of oscillation of the inverter circuit; and power regulation circuitry coupled to the inverter circuit to vary the frequency of oscillation of the inverter circuit such that power applied to the discharge tube remains within a range of a predetermined desired power magnitude while the discharge tube resistance varies with temperature during operation of the discharge arc, wherein the power regulation circuitry is inductively coupled to the inverter circuit through the use of a transformer and a primary winding of the transformer is coupled to the inverter circuit and a secondary winding of the transformer is coupled to the power regulation circuitry.