由於發光二極體具有點光源的特性,運用在直下式背光模組時須以陣列的擺放,來達到類似面光源的效果。然而發光二極體的種類、排列的方式、背光模組反射腔體的厚度與反射腔體的結構等因素會直接影響到液晶顯示器觀測面輝度均勻的程度。所以在背光模組系統中仍需各種的光學元件,如反射板、擴散板、增光片及反射式偏光增光片等來控制其系統之光學表現。 本研究提出一種直下式發光二極體背光模組腔體之反射結構,並希望減少使用任何光學元件而能達到背光模組系統所需之光學表現。該反射結構設計於反射腔體底部並圍繞側射型發光二極體,達到控制發光二極體分佈在主要角度的光線。探討各個反射結構參數對觀測面輝度均勻度及軸向發光強度之影響程度,並且使用光學模擬軟體設計反射結構形狀來控制光線的分佈情形以增加背光模組的輝度均勻度及軸向發光強度。模擬結果顯示在背光模組腔體中加入雙三角形反射結構,可以使輝度均勻度達到90%以上,以及軸向發光強度能有100%以上的增加。
Because Light Emitting Diode has a characteristic of the point light, when used in the direct Light Emitting Diode backlight unit they must put by way of array to get the result of similar to the area light. Furthermore, there are some factors, such as the kind of Light Emitting Diode, way to arrange, the thickness of the cavity of the backlight unit, the structure of the cavity and so forth, will influence intensity the uniformity of the observation surface of the liquid crystal display. So the backlight units still take various optical components in the system such as Reflector, Diffuser, Brightness Enhancement Film, and Dual Brightness Enhancement Film to control optics behavior. This paper proposed a novel direct Light Emitting Diode backlight unit without any optical component to reach optics behavior which the backlight unit system need by inserted some reflective structures. These reflective structures were designed on the base of the cavity and located around Light Emitting Diode to control light of Light Emitting Diode. We probed into the parameter of the each reflective structure influences the magnitude of the observation surface’s luminance uniformity and on-axis luminous intensity. This research designed the reflective structure’s shape by the optical simulation software to control the distribution of the light. It can increase the backlight unit’s luminance uniformity and on-axis luminous intensity. The simulation result showed that luminance uniformity wound get more than 90% and on-axis luminous intensity wound gain more than 100% as added the double reflective-triangular structure in the cavity.