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標題: | 顯示器背光源及畫素結構之先進光學設計與優化 Optical Designs and Optimization for Display Backlight and Pixel Structures |
作者: | 張洁瑞 Chi-Jui Chang |
指導教授: | 吳忠幟 Chung-Chih Wu |
關鍵字: | 裸眼立體顯示,準直背光,光能回收,OLED顯示器,環境光散射,抗反射,像素結構, autostereoscopic display,collimated backlight,light energy recycling,OLED display,ambient light scattering,anti-reflection,pixel structure, |
出版年 : | 2024 |
學位: | 博士 |
摘要: | 如今,隨著科學技術的不斷進步,顯示技術日益精進,應用日益普及。然而,由於人們對智慧生活的迫切需求,新世代的顯示技術也持續開發中。例如,元宇宙和自駕車這兩項具代表性的前瞻性技術所需之顯示技術。相對應地,立體顯示和戶外應用顯示器之顯示需求相伴而生,如何避免立體像素間的串擾和更高的環境光反射引起的低對比度等都是這些應用需面對的挑戰。在本論文中,我們研究可用於立體顯示器之準直背光的光學設計和優化OLED的像素結構來降低環境光反射解決這些問題,以求能提高先進顯示技術的影像呈現品質。
在本論文的第一部分。 我們透過結合線性光源陣列和精心設計的柱面透鏡陣列,研究具有簡單堆疊架構的高度準直和均勻的背光。使用傳統側發光式背光或直下式mini-LED (mLED)陣列作為光源、NiFe(不鏽鋼)的遮罩和透過成型製造的柱面透鏡陣列進行實驗來驗證所提出的設計和模擬。透過控制光源發散和優化透鏡設計,實現了高度準直的背光源,其發散角非常窄為±1.45°~±2.61°,均勻性為93-96%,場型中大角度的漏光也透過結構設計將其最小化。我們提出的架構提供了一種方便將市售常見背光源轉換為高度準直背光源的便捷方法,而高反射遮罩的應用也有助於回收光能並增強亮度。 在本論文的第二部分,我們深入研究如何最小化OLED顯示器中之環境光反射,這是OLED顯示器在戶外應用中的關鍵因素,以往人們會避免在強烈太陽光下注視螢幕,但對於車用顯示器而言則是一個無法避免的問題。雖然在OLED顯示器中加入圓偏振片已被證明可以有效抑制環境光反射,但我們的研究顯示,與OLED像素陣列中常見的像素定義層(PDL)和光間隔層(PS)相關的表面起伏將會引發散射反射,這導致環境光反射顯著增加,特別是在較大視角下。透過本研究中實驗研究和模擬研究的結合,我們引入了OLED像素結構的最佳化設計,包括對PDL和PS結構的改進,以便減輕散射反射的不利影響。這些最佳化設計預計將非常有利於在不同視角下實現一致的低環境光反射,從而增強 OLED 顯示器的整體觀看體驗。 Nowadays, with the continuous advancement of science and technology, display technologies have been continuously improved and widely applied. With people's demand for more intelligent life, next generation technologies are also being developed in full swing. For instance, the emerging metaverse and autonomous vehicles require even more advanced display technologies. In these technologies, autostereoscopic display and outdoor displays are facing unprecedented challenges, such as crosstalks between voxels and low contrast caused by higher ambient light reflection. In this dissertation, we address these issues by investigating the optical design of collimated backlight for 3D display and optimizing the pixel structures of OLED for lower reflection, aiming to enhance the image quality of advanced display technologies. In the first part of this dissertation. we study the highly collimated and uniform backlights with a simple stacking architecture, by combining linear light source arrays and carefully designed cylindrical lens arrays. Experiments were conducted to validate the design and simulation, using the conventional edge-lit backlight units (BLU) or the direct-lit mini-LED (mLED) arrays as light sources, the NiFe (stainless steel) barrier sheets, and cylindrical lens arrays fabricated by molding. Highly collimated backlights with small angular divergence of ±1.45°~±2.61°, decent uniformity of 93-96%, and minimal larger-angle sidelobes in emission patterns were achieved with controlled divergence of the light source and optimization of lens designs. The architecture we proposed provides a convenient way to convert available backlight sources into a highly collimated backlight, and the use of optically reflective barrier also helps recycle light energy and enhance the luminance. In the second part of this dissertation, we address the challenge of minimizing ambient light reflection for OLED displays, a crucial factor for the effectiveness of OLED displays in outdoor applications. In the past, people would avoid looking at the screen under strong sunlight, but this is an inevitable problem for automotive displays. While the incorporation of a circular polarizer in OLED displays has proven effective in suppressing ambient light reflection, our research reveals that the inherent surface undulations associated with pixel definition layers (PDL) and photo-spacers (PS), commonly found in OLED pixel arrays, can introduce scattering reflection. This results in an observable increase in ambient light reflection, particularly over larger viewing angles. Through a combination of experimental investigations and simulation studies presented in this research, we introduce optimized designs for OLED pixel structures, including improvements to PDL and PS structures, aimed at mitigating the adverse effects of scattering reflection. These optimized designs are anticipated to be highly advantageous in achieving consistently low ambient light reflection across various viewing angles, thereby enhancing the overall viewing experience of OLED displays. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/92550 |
DOI: | 10.6342/NTU202400831 |
全文授權: | 同意授權(限校園內公開) |
顯示於系所單位: | 電子工程學研究所 |
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