LED側發光型擴散式背光模組之分析

Abstract

在現代資訊科技的演化進步中，顯示器一直是個很重要的一環，當傳統的CRT螢幕漸漸被TFT-LCD所取代後，平面顯示科技就成為了目前的主流技術，而且在環保議題倍受重視的今天，較高發光效率設計與較環保的光源如LED光源的應用就變得越來越重要。由於LED相較於CCFL燈管具有無汞、高色彩飽和度、快速反應及壽命長等特點，所以被視為下一代平面顯示器的重要替代光源。 本論文主要討論的是LCD顯示器中的背光模組設計，我們使用了LED作為主要的光源，並應用了折疊式混光設計，將可以縮短混光所需的距離，在本論文中所研究的背光模組主要是由一側發光型擴散式導光板所構成，利用導光板中的高散射微小球形顆粒與底面的微結構排列，將光線導引至垂直面向，進入液晶面板層而達到平面均勻背光源之設計目的，這樣的設計可以減少傳統光學膜片的使用，如增亮膜與擴散膜，並且提高發光效率。 在本論文中，我們使用了LightTools光學軟體作為設計模擬的軟體，並將探討關於此背光模組設計的均勻度、光學效率、以及色彩差別度等分析項目。 最後在經過妥善的調整後，我們所設計的背光模組可達到均勻度93.1%以上，而其光學效率在不使用BEF與Diffuser光學膜片的情況下，可以較傳統的背光模組提升76%，並且將色彩差別度維持在良好的範圍內。

As the information technology progresses, the display technology always plays an important role. In recent years, the CRT monitor has been substituted by TFT-LCD gradually and flat panel displays have become the main stream products already. In this thesis, we design a simulation model of edge-lit diffusive type backlight system. Unlike the conventional backlight system, the diffusive type backlight system contains no enhancement film or diffusive film. The micro-particles blended in the light guide plate and the micro-structures on the bottom surface will affect the propagation of light path to vertical direction and enhance the lighting efficiency. Besides many countries and organizations in the world pay attention to the environmental subject, the backlight system constructs of LED becomes more and more popular. The LED backlight has advantages of higher color saturation, faster response time, free of mercury, long life-time, etc. We make use of a suit of commercial software LightToolsTM to model a folding type of LED backlight system and to analyze the uniformity, optical efficiency, and color dispersion of the system. Based on our design, the uniformity of our backlight modules can be adjusted to achieve 93.1% or above. The color dispersion of these modules is quite acceptable. The optical efficiency of the backlight module without using BEF and optical diffuser film can be raised to 76% better than that of conventional backlight module.