垂直配向邊緣場效驅動液晶顯示器的反應時間之研究

Abstract

延續VAFFS(Vertical alignment fringe-field switching)之研究，2D VAFFS利用正型液晶達到了極快的反應速度，3D VAFFS則可利用負型液晶達到高穿透率，缺點為拉長電壓週期後造成兩步驟轉動(Two-step process)，虛擬牆將會消失而使反應速度下降，以往研究中發現改變電極圖案設計可以延長虛擬牆存在時間，擁有高穿透率，改善兩步驟轉動的影響，並對其中的機制加以說明。 此論文則提出限制電壓週期的觀點，希望有足夠時間施加電壓，驅使液晶達到高穿透率，並在兩步驟轉動發生前就歸零電壓，這項方法得到了不錯的穿透率與很短的反應時間，並能再縮小電極尺寸，得到更短的反應時間。 3D VAFFS_com則是在上方加入一整片共用電極，使得我們在原有的水平方向電場基礎上多加入垂直方向電場，除了使用負型液晶模擬外，也利用正型液晶模擬，兩者會有完全相反的影響，能幫助我們對於3D VAFFS_com的實際效果有更深入的認識。

Continuing the study of VAFFS in which liquid crystals with positive anisotropy were used in 2D VAFFS to achieve fast response time, liquid crystals with negative anisotropy have also been used in 3D VAFFS to reach higher transmittance. However, in the case of 3D VAFFS, a two-step process may occur after we lengthen the applied voltage period. As a result, the virtual wall can disappear that makes response speed slower. In the previous study, it has been found by changing the pattern design of electrode we could extend the existence of virtual walls. This finding not only has high transmittance but also improves the effect of two-step process and explains the mechanism in it. This paper proposes the idea of limiting the applied voltage period. We hope there will be enough time to apply voltage, to drive the liquid crystal to reach high transmittance, and to return the voltage to zero before a two-step process occurs. In this way, we can obtain good transmittance, fast response time, and reduce the electrode size to reach faster response time. 3D VAFFS_com design is to add a whole piece of common electrode at the top. It will add vertical electric field to the existing horizontal electric fields. In addition to using liquid crystals with negative anisotropy in simulations, we here also use liquid crystals with positive anisotropy. These two designs can have completely opposite effect that can help us understand more about the design of 3D VAFFS_com.