Digital-Dimming Controller With Current Spikes Elimination Technique for LCD Backlight Electronic Ballast

Abstract

A novel simple control strategy to improve the ignition behavior of a cold cathode fluorescent lamp (CCFL) in digital-dimming mode is proposed in this paper. Due to restriking manipulation in the digital-dimming mode, the lamp life of CCFL is reduced substantially. For extending the lamp life, a digital-dimming controller with current spikes elimination technique is realized to reduce the high ignition voltage and eliminate the ignition current spike. The half-bridge resonant inverter is employed in the presented backlight system to assess the system performance. Complete analysis and design considerations are discussed in detail in this paper. Experimental results agree with the theoretical prediction. The overall efficiency of the system achieved at the rated power is over 84.9%. The ignition voltage is reduced about 30% without any lamp current spike that occurred under digital-dimming operation