運用新型電極結構提升負型垂直配向邊緣場效驅動液晶之虛擬牆穩定度

Abstract

液晶顯示器作為現今廣泛使用及成熟的產品，具有多元的應用領域，而FFS(fringe-field switching)驅動方式有著廣視角、高亮度等多項優勢。因此先前研究中針對正型液晶驅動之2D VAFFS、負型液晶驅動之3D VAFFS有過深入的探討，同時也發現FFS中向錯(disclination)也就是虛擬牆對於加快反應時間的影響，故嘗試以電極結構設計方式使虛擬牆於長時間信號輸入下仍然存在，並已有成效。 本論文中結合先前研究之結論，針對孔洞結構進行分析，探討孔洞數量與形狀對於反應時間、穩定度之關係。後續討論中因對稱電極自身具有高穩定性，因此提出對稱電極結構概念，並分析對稱圖案之形狀優劣，同時以多種液晶進行模擬，來了解此結構之泛用性。 為改善液晶之水平連續橫向力，我們結合過去結論提出含有孔洞、旋轉45度之十字型對程圖案電極結構，發現此結構在不同尺寸面積下都具有良好的穩定度、高穿透率以及快速的反應時間，且同時針對多種液晶進行模擬以獲得更全面之結論。

As a widely used and mature product nowadays, liquid crystal displays have multiple application fields. The traditional FFS (Fringe-Field Switching) driving method has many advantages, such as wide viewing angle and high brightness. In recent years, research has delved deeply into studies on e.g. 2D VAFFS which employs positive liquid crystals and 3D VAFFS that employs positive or negative liquid crystals. It has been found that disclination, also known as virtual wall, in VAFFS is a key factor that helps speed up the response time. It has also been found that new designs of the VAFFS electrode structure may help make virtual wall exist more continuously (i.e. more stable) under long-term signal input. This approach has been quite effective so far. In this thesis, based on the conclusions of previous studies, we aim to focus on analyzing hole-pattern structure. We also discuss the effects of different shapes of hole and number of holes on the effects of response time and stability. We also found that high stability of virtual wall tends to exist around symmetrical electrode patterns. We thus proposed the concept of using symmetrical electrode structure to stabilize the virtual walls. We analyzed the advantages and disadvantages of different shapes of symmetrical electrode pattern. In order to cancel the horizontal continuous lateral force of the liquid crystal, we combined the previous results and conclusions and proposed a new cross-shaped symmetrical electrode structure that contained holes and the structure was rotated by 45 degrees. It is found that this new structure can have good stability, high transmittance and fast response time under different sizes and pixel areas. We analyzed the results using different kinds of negative-type liquid crystals in order to make sure that the conclusion can be consistent even in different conditions.