藍光LED背光模組漏光改善之研究

Abstract

過去欲得到較佳的顯色效果，在LED的選用上有幾種方式，第一種是藉由RGB三色來進行混光，以達到白光的效果，但RGB三色LED要完整呈現白光且達到混光均勻仍有一定的困難度；第二種是選用藍光LED搭配紅、綠螢光粉的白光LED，藍光LED藉由紅色和綠色螢光粉激發出白光，目前廠商預估約可將NTSC色域由72%提升至85%，提昇色域的效果有限。 而另外一種方式就是藉由量子點增強膜(Quantum Dot Enhancement Film)來達到廣色域的目的，可將NTSC色域由72%提升至約100%，其需搭配藍光LED，但由於LED光源為藍光，不同於以往常用的白光LED，所以一般常見光學問題如漏光及亮暗紋等均會變為藍色光暈。 本研究針對改善漏光現象進行相關的研究分析，利用光學模擬軟體分析漏光成因，設定擋牆距離和擋牆斜角進行漏光分析研究，找出最適合的參數條件，分析整體漏光改善的程度，並提升畫面均勻度。實驗結果證明，擋牆角度在30度時，其出光側能量為最低，整體畫面均勻度達到72.8%，可達到降低漏光的程度。

In the past, several approaches of using light-emitting diodes (LEDs) to achieve high-quality color display have been used. The first approach involves mixing red–green–blue (RGB) colors to achieve white light. However, obtaining pure white light and light uniformity by using LEDs with RGB colors remains technically challenging. The second approach entails using a blue-light LED with white-light LEDs that comprise red–green phosphor. The blue-light LED excites the white light through the red and green phosphors. Currently, manufacturers can expand a never the same color gamut(NTSC) from 72% to 85%; however, such increase limits the improvement of color gamut. Another approach involves using quantum dot enhancement film to generate a wide color gamut, in which NTSC gamut increased from 72% to approximately100%. However, because blue-light LEDs differ from commonly used white-light LEDs, the use of blue LEDs engenders optical problems such as light leakage and glare appearing as a blue glow. Therefore, this study addressed the light leakage problem. The causes of light leakage were analyzed using optical simulation software, in which wall distance and angles were specified to identify optimal parameters. Subsequently, the extent to which overall light leakage improved was determined and display uniformity was enhanced. The experimental results showed that when the wall angle was 30°, the energy at the light-emitting side was the lowest and the overall display uniformity achieved 72.8%; thus, light leakage was effectively reduced.