Patent ID: 8294384
Filing Date: 2012-10-23
Classification: H05B

Abstract:
1. An electronic ballast for high frequency lighting of a discharge lamp having lamp filaments and operating in a preheating mode, a starting mode, a first lighting mode, and a second lighting mode, the electronic ballast comprising: an inverter; a main resonant circuit coupled to the inverter; and a preheating circuit having a winding component connected in parallel with the main resonant circuit, the winding component comprising a primary winding and a secondary winding, and a switch connected in series with the primary winding; wherein a path of a current flowing in the primary winding of the winding component is switched ON by the switch in the first lighting mode and OFF in the second lighting mode, wherein the first lighting mode has a rated lamp output and the second lighting mode has a dimmed lamp output, wherein a constant preheating current for filaments in the lamp is supplied from the secondary winding of the winding component during the preheating mode, the starting mode, and the second lighting mode of the discharge lamp.