三維電極結構之垂直配向邊緣場效驅動液晶顯示器元件模擬

Abstract

在現今社會，液晶顯示器已經隨處可見。快速的響應時間是顯示器的一項重要因素，因為其可以避免問題如動態影像模糊。為了實現高穿透率和快速響應時間，本篇論文將針對具有快速響應時間和高穿透率的垂直配向邊緣場效驅動模式（VA-FFS）進行電腦模擬。我們實驗室發表的「Effects of electrode structure and dielectric anisotropy on the performance of VA-FFS LC mode」中[43]，討論除了介電各向異性外，具有相同材料參數的正負型液晶，這使得介電各向異性成為引起響應時間差異的主要因素。在與參考文獻[43]相同的條件下的VA-FFS模式，我們將於接下來的討論中進一步發現許多有趣的現象。例如我們將討論二維和三維結構中的電場分佈，從不同的角度給出見解。我們發現負型液晶在三維結構中的非均勻穿透率較不穩定，穿透率不均勻的機制可以透過洞穴區域（電極間隙）中負型液晶分子的旋轉來解釋。同時，本篇論文中亦針對負型液晶在三維結構中的旋轉過程進行研究，以說明“兩步驟”過程，並且將討論改善穿透率的方法。本文分別介紹了上升時間和下降時間的“兩步驟”過程。最後，我們討論了8階灰度表，以進一步檢查不同灰階之間的響應時間，並幫助確定三維VA-FFS模式的平均響應時間。

Nowadays, liquid crystal displays can be seen everywhere. Fast response time is a significant factor for the displays because, e.g. unwanted motion blur can be avoided. In order to achieve high transmittance and fast response time, simulation of vertically-aligned fringe field switching (VA-FFS) mode which features fast response time and high transmittance is discussed in this thesis. In “Effects of electrode structure and dielectric anisotropy on the performance of VA-FFS LC mode”[43] published by our laboratory, there are discussions about positive and negative LC with identical material parameters except for the dielectric anisotropy. This makes dielectric anisotropy as the major factor for contributing the difference in response time. Based on VA-FFS LC mode with same conditions as in Reference[43], we further discover many interesting phenomena in this thesis. For example, electric field distributions in 2D and 3D structures are discussed to give new insights from different aspects. Non-uniform transmittance in 3D structure with negative LC is discovered which leads to less stable transmittance. Mechanisms of non-uniform transmittance can be explained by the rotation of molecules of negative LC in the hole regions (electrode gap). Rotation processes in 3D structures with negative LC are examined to illustrate the “two-step” process and methods for improving transmittance will be discussed as well. “Two-step” process parts of rise time and fall time are also individually presented in this thesis. Finally, we also discuss about 8-level gray-to-gray scales to further examine the response time between different gray levels and help determine the average response time of 3D VA-FFS LC mode.