跨尺度之先進顯示器元件設計模擬與應用

Abstract

顯示技術的演進改變了人類對視覺資訊的感知與互動方式，範圍涵蓋廣及個人消費型電子產品到大型公共顯示。除了發光材料與驅動電路的創新外，光學結構亦對顯示特性具有關鍵影響，透過調控光線的萃取、傳輸與塑型，進而改善顯示器的效率、角度分佈、色彩準確度、對比度與整體影像品質。傳統平面顯示面板中常應用微透鏡陣列、多層薄膜、擴散片、梯形反射壁結構與黑色矩陣等光學元件，以提升光效率、控制視角或抑制反射。與此同時，新興應用如可摺疊與可捲曲裝置、沉浸式擴增/虛擬實境（AR/VR）系統、車載顯示、高動態範圍（HDR）顯示器及光場顯示等，皆推動了從毫米至奈米尺度的多樣化光學結構需求。在巨觀尺度下，光的傳播主要受幾何光學支配；當結構尺寸接近光波長時，幾何光與波動光的效應同時顯現；而在次波長尺度中，則以波動光學為主導，藉由例如超構表面或光柵等奈米結構達到精確的振幅、相位與偏振狀態控制。本論文的研究動機即在於探討如何透過跨尺度光學結構設計，以克服次世代顯示器在效率、均勻性及影像品質改善上的挑戰。 本論文的第一部分探討曲面基板對影像顯示的影響。軟性與曲面 OLED 面板可實現新穎的顯示器外觀設計，但同時改變了光線入射與出射基板的角度。我們推導了光線從顯示元件至空氣各界面的入射角與出射角的幾何關係，用以模擬在凸面圓柱與凹面圓柱結構中的發光、折射與透射行為。研究顯示，曲率造成的發光面與出射面的角度不匹配會導致影像扭曲與亮度不均。透過逆向座標映射及不同位置、不同出射角的亮度補償所建立的影像修正方法，有效還原影像扭曲並達到發光範圍的亮度均勻，為高品質曲面顯示提供一項可行的光學解決方案。 第二部分我們聚焦於 mini-LED 背光的亮度均勻度提升與碳足跡降低。為提升直下式背光 LCD 的效率並減少功耗，本研究提出一種複合型階梯式mini-LED 封裝結構，結合毫米級曲面與 10–100 µm 大小階梯結構，以更精確控制LED的出光場型。幾何光追跡與混合光學模擬(幾何-波動)結果顯示，優化後的封裝結構可在僅 3 mm 的光學距離內達成超過 90% 的光學效率與 80% 的亮度均勻性，有效減少 LED 數量與封裝材料的使用。當階梯尺寸縮小至約 10 µm 時，繞射效應顯現並造成微幅的光線擴數，對均勻度又略有提升。此階梯狀設計除具備薄型化與高效率的特性外，還可適用於大面積射出成形的製程。 第三部分則探討將奈米尺度的偏振調控超穎表面應用於3D光場顯示。我們開發了一種結合偏振切換的扭曲向列液晶元件與準直背光的偏振調控的偏折式超穎表面，實現以時間多工達到雙倍角解析度的光場顯示架構。首先，建立了品質穩定的 TiO2 超穎表面製程，以確保高結構精度與良好光學性能。每一個 TiO2 超穎表面子像素可將兩種正交偏振光分別偏折至不同方向；九個超穎表面子像素與其對應的顯示器子像素共同構成一個光控制單元，可以產生 18 個獨立視角，相較傳統無時間多工架構的3D顯示器多了兩倍角度解析度。實驗結果證明了切換偏振的光束轉向，並且偏折誤差小於 0.2°，且當與 ±1.1° 的準直背光整合時，多數視角間的串擾低於 5%。此外，我們也以15 × 15個控制單元的超穎表面做為原型，展示了全彩四視角的立體影像顯示，驗證了利用極化調控超穎表面實現時間多工光場顯示架構的可行性。

The evolution of display technologies has reshaped how humans perceive and interact with visual information, from personal consumer electronics to large-scale public displays. In addition to innovations in emissive materials and driving circuits, optical structures typically influence display performance by modulating how light is extracted, guided, and shaped, consequently affecting efficiency, angular distribution, color fidelity, contrast, and image quality of the displays. For example, traditional flat panels employ microlens arrays, multilayer thin films, diffusers, bank structures, and black matrices to improve their efficiency, control viewing angles, and suppress reflections. Meanwhile, emerging applications such as foldable and rollable devices, immersive augmented reality (AR)/virtual reality (VR) systems, automotive dashboards, high dynamic range (HDR) monitors, and light-field displays have driven the need for increasingly diverse optical structures ranging from millimeter scales down to nanometer scales. At macroscopic scales, geometric optics governs light propagation, whereas at scales on the order of the optical wavelength both ray-based and wave-optical effects become significant. At subwavelength scales, wave optics dominates, and nanostructures such as metasurfaces and gratings enable the control of amplitude, phase, and polarization of light. The motivation of this dissertation is to explore how multi-scale optical structures can be engineered to overcome challenges in efficiency, uniformity, and image fidelity for next-generation displays. In the first part of the dissertation, we investigate how displayed images are influenced by curved substrate. Flexible and curved OLED panels enable novel form factors but inevitably alter optical paths and perceived images. A geometric-optics framework was developed to analyze emission, refraction, and transmission in cylindrical convex and cylindrical concave structures. The curvature-induced mismatch between the emission and exit surfaces was shown to cause geometric distortion, along with brightness variations across the screen. A corresponding correction method, derived from inverse coordinate mapping and angle-dependent intensity compensation, successfully restored proper image aspect ratio and uniform brightness, providing a practical solution for high-quality curved displays. In the second part, we focus on improving the luminance uniformity and carbon footprint of the mini-LED backlight. To enhance luminance uniformity and reduce power consumption in direct-lit LCDs, a composite stepped-shape mini-LED packaging structure was proposed. The design integrates millimeter-scale freeform profiles and 10–100 µm micro-steps to control emission more precisely. Both ray-tracing and hybrid geometric-wave optics simulations confirmed that the optimized packaging structure achieves over 90% optical efficiency and 80% luminance uniformity within a 3 mm optical distance, and indicated that the stepped structure can potentially reduce LED counts and material usage. Meanwhile, diffraction effects emerging at the 10 µm scale were shown to further enhance beam broadening, leading to a slight improvement in luminance uniformity. This design offers a thin and energy-efficient backlight architecture suitable for large-scale injection molding. In the third part, the nanoscale, polarization-dependent deflection metasurface combined with a twisted nematic liquid-crystal device and a collimated backlight was developed to realize a time-multiplexed, angular-resolution-doubled light-field display. A robust fabrication process for TiO2 metasurfaces was established to ensure high structural fidelity and optical performance. Each TiO2 metasurface sub-pixel is designed to deflect orthogonal polarizations into two distinct directions. A group of nine metasurface sub-pixels and their corresponding display sub-pixels together constitute a control unit, enabling the generation of 18 distinct views within a compact configuration. Experiments confirmed < 0.2° deflection error, polarization-switchable beam steering, and most inter-view crosstalk < 5 % when integrated with a ±1.1° collimated backlight. Furthermore, a 15×15-control-unit prototype demonstrated full-color four-view 3D imaging, confirming the feasibility of employing metasurfaces for the time-multiplexed display architecture.