Analysis of balancing driver for multiple cold cathode fluorescent lamps

This paper proposes a novel scheme to drive the cold cathode fluorescent lamps (CCFLs) for liquid crystal display (LCD) in direct-type backlight module. The topology is capable of driving an arbitrarily even numbers of lamps with same lamp current without add to balancing circuit, while achieving significant size, weight, and cost reduction. This proposed scheme is composed of series CCFLs and the secondary side of transformers, with the aim to alleviate the influence of parasitic capacitance induced in between the interface of lamps and the aluminum back-plank and thus to balance the lamp currents .and light output. A prototype of the multi-CCFLs driver is designed and built for a backlight module with 14 lamps in a 32-inch LCD. Experimental results demonstrate the effectiveness and feasibility of the current´s balance scheme.