高分子於光學補償彎曲液晶顯示模態之應用

The Applications of Polymer Polymerization on Optically Compensated Bend Cell

吳俊傑(J. J. Wu) ； 林子原(T. Y. Lin) ； 吳聲明(S. M. Wu) ； 張松曜(S. Y. Chang) ； 范士鴻(Shing-Hu Fan) ； 葉逸彥(Yi-Yen Yeh)

《光學工程》 98期 (2007/06) Pp. 25-31

https://doi.org/10.30011/OE.200706.0004

摘要

OCB(Optically Compensated Bend) Mode，又稱π-cell，即光學補償彎曲模式。液晶分子沿著液晶層厚度方向以上下對稱的方式呈現彎曲排列，同時有著廣視角及電光學應答速度快的優點，被視為可用於液晶電視及監視器等次世代的液晶顯示模式。可是這種模式目前尚有須要克服的技術問題，就是由初期狀態為擴散配向(splay alignment)轉移到彎曲配向(bend alignment)時，需要施加較大的轉態電壓VS-B來克服自由能障礙，才能使彎曲狀態的配向趨於穩定。
我們的研究中，將少量的高分子單體混入液晶，造成一種低轉態電壓VS-B的π-cell。發現這種cell仍然具有傳統π-cell之快速光學響應特性，而且在低電壓下比較容易穩定於bend，有些cell甚至不加驅動電壓時也能直接穩定於bend狀態。
這種π-cell之製造方法是將混入高分子單體的液晶注入空cell中，並照射紫外光(UV)，同時在該π-cell上加入交流方波電壓(VUV)，使單體分子於液晶層表面聚合成高分子網(polymer networks)或牆(polymer wall)的結構。
我們研究該π-cell的光電特性。經過實驗量測後，發現高分子網和高分子牆會影響液晶分子的配向狀態與預傾角角度，並有效地降低了轉態電壓VS-B。

關鍵字

π-cell ； 光學補償彎曲模式 ； 高分子網 ； 高分子牆

並列摘要

OCB (Optically Compensated Bend mode or π-cell) is promising as the next generation display mode, due to its fast response and wide viewing angle. However this mode has some intrinsic problems. Firstly, it has long warm up time; it takes long time to shift from splay alignment to bend alignment because it stays on splay alignment at initial state. Secondly, it has high critical voltage; high energy barrier must be overcome to shift from splay alignment to bend alignment. Thirdly, bend configuration at low driving field is unstable.
This study employed the mixture of nematic liquid crystal and monomer to prepare sample cells. We designed a π-cell with fast optical response but without the unstable problem, and removed the warm up time successfully. To make theπ-cell, high voltage was applied on cells as being irradiated by UV light. After UV curing, the liquid crystal molecules were aligned with polymer network or polymer wall. The experimental results showed the transform voltage at which from splay to bend alignment will be decreased due to the polymer bundles.

並列關鍵字

π-cell ； OCB mode ； polymer network ； polymer wall