Analysis of Current Distribution in Driving Multiple Cold Cathode Fluorescent Lamps (CCFL)

Cold cathode fluorescent lamps (CCFLs) show complex characteristics, which make it difficult to drive them in parallel. In this paper, a backlight inverter, which can drive multiple CCFLs using single controller and single switching network, is presented. The analysis of the lamp current distribution is presented in detail. The current-balancing condition, under which the lamp currents are well balanced in the presence of the lamp voltage variation, is derived. The effect of the resonant component variation is also investigated. The analysis results are verified from experiments with two 720-mm/4-mm CCFLs for 32-in liquid crystal display televisions. Experimental results with eight CCFLs are also presented in the presence of the lamp voltage and the resonant component deviation