透過您的圖書館登入
IP:34.234.83.135
  • 學位論文

垂直配向液晶顯示元件之研究

Study on Vertical Aligned of Liquid Crystals Display Devices

指導教授 : 吳俊傑 陳殿榮

摘要


強誘電性液晶在垂直配向液的作用下,其配向的均勻性取決於液晶盒間隙(d)與液晶螺旋距(p)的比值(d/p)。當d/p<1時,液晶分子在液晶盒內隨機的排列造成缺陷的產生。另一方面,若d/p>1時,液晶分子呈現螺旋排列且其平均光軸垂直基板,因此可得到均勻的暗態。然而在驅動時,由於要使液晶分子達到解旋狀態所需的電壓太高(約50V)而限制了其應用的價值。 為達到均勻的配向以及降低驅動電壓,本實驗研究垂直配向強誘電性液晶。 利用摩擦配向法,經由改變rubbing的方式(同向與反向)以及強度,在液晶盒間隙(d)與液晶螺旋距(p)的比值小於一(d/p<1)的情況下,探討液晶盒之配向均勻性以及光電特性。此外,也利用模擬軟體DIMOS,具體說明液晶分子的排列以及驗證實驗的結果。 實驗中具有N*-SmC*相順序之強誘電性液晶。首先我們探討同向與反向rubbing液晶盒。實驗中發現,當d/p<1時,在反向rubbing 條件下會呈現解旋的狀態且液晶分子會往rubbing方向傾倒形成高傾角的排列而得到均勻的排列。在進行conoscopy觀察時,會發現十字紋往rubbing 方向傾斜。另一方面,同向rubbing的條件會使得液晶分子由下基板往上基板呈現180度的旋轉。隨著液晶盒厚度的增加,會有twist區塊的產生而產生缺陷。根據此點,我們另外利用於N*-SmC*相轉移過程施加交流電場消除twist區塊,亦能達到均勻配向。 在驅動方面,我們使用水平以及ㄑ字型電極量測其光電特性。由於d/p<1,在本質上幾乎液晶分子的排列已達解旋的狀態。我們由結果得知,不論在同向或反向rubbing的條件下,皆可得到無臨界電壓的驅動且其飽和電壓和原本無rubbing的液晶盒相比,亦大大的降低。

並列摘要


For the Vertical Configuration Ferroelectric Liquid Crystal(VC-FLC), the uniformity in the alignment of the FLC cell depends on the ratio between the cell gap(d) and helical pitch(p). When the d/p<1, FLC molecules tilted in random direction and resulted in a non-uniform alignment. On the other hand, the condition of d/p<1 indicated the FLC can rotate over a period in the cell so that the average molecular axis was crossed to the substrate plane. In this situation, uniform dark state can be obtained. When driving the cell with d/p>1, however, the required electric field for unwinding the helical structure of FLC was too large to be used in the nowadays driving scheme for liquid crystal display. To show uniform alignment and reduce the driving voltage, the VC-FLC with rubbing method was studied. In this thesis, the uniformity of alignment and electro-optical characteristics as functions of rubbing processes(parallel and homogenous rubbing) and rubbing strength was discussed under the condition of d/p<1. Moreover, the experimental results were also clarified by using the DIMOS simulation software. In the experiment, we used the FLC material showing N*-SmC* phase sequence and all cells had the condition of d/p<1. In the homogeneous rubbing cell, all molecules were unwounded and tiled with respect to the rubbing direction. Therefore, the average molecular axis tilted an angle with respect to the normal direction of substrate plane and uniform dark state can be obtained. In the parallel rubbing cell, on the other hand, the molecular structure showed 180 rotations from lower substrate to the upper one so the twist domain were formed in the alignment and the probability of the formation of twist domain increased as the cell gap increased. For this problem, we used the methods of applying ac electric field during N*-SmC* phase transition to eliminate the twist domain and get uniform alignment. To drive the VC-FLC cell, two kinds of electrodes, transverse and zigzag electrodes, were used. The results indicated that both the homogeneous and parallel rubbing cell showed threshold-less voltage and the saturation voltage were also reduce in comparison with the VC-FLC cell without rubbing process.

參考文獻


[4] 楊俊宏, “廣視角配向控制對於液晶分子運動影響的研究”,
[31] 楊秋蓮,快速光學響應液晶原件之動態機制研究,博士論文,
[6] Y. Ito, R. Matsubara, R. Nakamura, M. Nagai, S.
[5] Tetsuya Miyashita, Yoshimi Yamaguchi and Tatsuo
[26] Aira Hotta, Ray Hasegawa and Kohki Takatoh,” Effect

被引用紀錄


胡水上(2013)。高分子穩定型藍相液晶光電特性之模擬研究〔博士論文,國立臺北科技大學〕。華藝線上圖書館。https://doi.org/10.6841%2fNTUT.2013.00561
王奕凱(2013)。高分子穩定型FLC液晶盒的配向技術與光電特性研究〔碩士論文,國立臺北科技大學〕。華藝線上圖書館。https://www.airitilibrary.com/Article/Detail?DocID=U0006-1507201315334100

延伸閱讀