Low frequency architecture for multilamp CCFL systems with capacitive ignition

This paper presents a low frequency architecture for driving parallel cold cathode fluorescent lamps (CCFLs) in large screen LCD TV backlighting applications. Key to the architecture is a proposed capacitive coupling approach for AC lamp ignition. The system consists of a single high voltage converter, an AC lamp ignition circuit, current regulation devices and a single primary controller. The topology is capable of driving an arbitrary number of parallel lamps with independent accurate lamp current regulation, while maintaining high efficiency and achieving significant size, weight, and cost reduction when compared to typical high frequency AC ballast designs. Experimental results for a pair of parallel 800 V 40 cm CCFLs demonstrate simultaneous ignition and DC current regulation