An Energy-Recycling (ER) Technique for Reducing Power Consumption of Field Sequential Color (FSC) RGB LEDs Backlight Module

• Main Authors: Tsai, Yueh-Chang, 蔡岳璋
• Other Authors: Chen, Ke-Horng
• Format: Others
• Language: en_US
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/75940491897364195665

碩士 === 國立交通大學 === 電機學院碩士在職專班電機與控制組 === 98 === The field sequential color (FSC) technology with RGB-LED backlight modules can achieve high color saturation and better color gamut compared to conventional cold cathode fluorescent lamp (CCFL) backlight. Owing to the remove of color filter, the display brightness can be promoted to about three times that of the original one with color filter. Besides, both display power consumption and cost can be decreased greatly due to the disappearance of color filter. The proposed energy-recycling (ER) technique for the FSC display with RGB-LED backlight modules can dynamically switch the output voltage to 36 V for twelve green/blue LEDs in series or 24 V for twelve red LEDs in series according to each color sequence in the FSC technique. As a result, it can reduce 13% of total energy during the red color display period. The current commercial chip can’t satisfy all the functions in the ER technique; thus, a fabricated ER-controller with a commercial IR-2184 driver, which is used to drive independent high/low side power MOSFET with a fixed dead time, synchronous rectification (SR) control function, can implement the ER technique to meet the basic requirement of system. The ER control, which is used to replace the commercial AC-DC converter control further, can operate at the boundary current mode (BCM) with a zero current detection (ZCD) function to trigger the next switching cycle. The ZCD function is achieved by the enhanced current sensing (ECS) circuit, which can satisfy the need of system control to prove the feasibility of the ER technique. The proposed ER technology can accelerate the settling time of the output voltage since the energy that needs to be dissipated by load or leakage is stored to an energy-recycling capacitor from the output capacitor when the driving voltage is switched from 36 V to 24 V; that is it can further reduce 17% of dissipation energy. Specially, it only uses one recycling capacitor and one Schottky diode connected at the power structure of synchronous buck-boost converter.