摘 要 本論文研究了一種適用於大尺寸液晶顯示面板之LED背光驅動電路。藉由採用單級充電幫浦非對稱半橋轉換器,可以達到高效率、高功率因數、簡化電路以及低成本等特性。為調節LED背光系統之LED電流與亮度,數種均流方法被討論與比較。並聯LED之均流與亮度平衡都能滿足,且電流漣波也能有效地消除。也加入旁路二極體設計,當LED損壞時,得以提供替代電流路徑以避免LED熄滅,因而提升了LED背光系統的可靠度。本論文亦建立與測試一雛型電路,其模擬與實驗結果用於驗證了所提出的方法之可行性。
Abstract This thesis presents a LED backlight driving system for large-scale of LCD panels. High efficiency, high power factor, circuit simplicity, and low cost can be achieved by using a single-stage charge-pump asymmetrical-half-bridge converter. To regulate the LED current and brightness for the LED backlight system, some current sharing methods are presented and compared. The requirements for the current sharing and luminance balance among paralleled LED arrays can be satisfied while current ripple is eliminated significantly. Because of the addition of bypass diodes, an alternative current path can be offered when a single LED fails. The LED array will not distinguish. Reliability of the LED backlight system can thus be improved effectively. A laboratory prototype has been built and tested. The simulation and experimental results are shown to verify the feasibility of the proposed method.