The design and implementation of a new digital dimming controller for the backlight resonant inverter

This paper presents a new digital dimming controller (DDC) for the backlight resonant inverter to improve the ignition behavior of the cold cathode fluorescent lamp (CCFL) and, hence, to increase the CCFL's lifespan. The DDC using a soft-starting technique (DDC-SST) is designed and developed to reduce the high ignition voltage and to eliminate the ignition current spikes. A full-bridge resonant inverter is adopted in the backlight system. The design considerations along with a complete analysis for said controller are detailed. Encouraging experimental results in close agreement with the theoretical analysis are also exhibited. The overall system power efficiency is approximately 85%. The ignition voltage is reduced by around 30% without any lamp current spike occurring during the dimming control operation. The apparent advantages of the proposed dimmer are listed in the conclusion.