本論文，將介紹兩種新型設計之直下式背光模組。首先，利用布魯斯特角(Brewster’s angle)原理，設計一偏極光反射板之直下式背光模組，將背光模組所提供之入射光源，分成兩垂直之偏振態。背光模組過濾掉p-polarized light，而s-polarized light反射射入液晶面板。其目的在產生線性偏振光源，供LCD面板使用。利用偏極光反射板，將光分離成獨立之偏振態，提高線性偏極化光之輸出，降低LCD偏光片(Dichroic polarizer)的吸收。相較於一般傳統式之非偏極化光輸出的直下式背光模組而言，偏光片穿透率由43%提高至71.7%，亮度輸出效率增加38%。 最後，討論擴散板與反射板幾何形狀改變後，對光使用效率與光均勻度的影響。並結合擴散板與稜鏡片功能，設計一菲涅爾透鏡與半圓燈罩式擴散片，取代傳統擴散板，討論其光使用效率與光均勻性。 In this paper, we will introduce two novel design methods for a direct backlight module. First, a direct backlight module with polarized reflector at Brewster’s angle is designed. The brightness and transmittance of this new module is simulated by using optical simulation software. The S-polarized component of the input light is reflected into the backlight system and the P-polarized component is transmitted through the reflector. The polarized reflector technology is to eliminate the absorption loss of dichroic polarizer of a LCD. The loss in the dichroic polarizer is reduced by the use of a backlight with polarized reflector which produces linearly polarized light output. The transmittance of polarizer of this backlight system is improved to 71.7%, compared to 43% of the conventional backlight. The brightness gain also shows 38% improvement. Finally, we will discuss the effect on light efficiency and irradiance uniformity for geometry modification of diffuser sheet and reflective sheet. The light efficiency and irradiance uniformity of Fresnel lens sheet and semi-circular diffuser sheet which composed of diffuser and prism function are also discussed here.