垂直配向邊緣場效驅動之負型液晶運用新型電極結構之研究

Abstract

隨著時代科技的發展，人們每天都花非常多在具有顯示器之產品，從手機、手錶到電視與商店櫥窗的螢幕等，非常多的顯示器刻印在日常生活當中，可見顯示器的需求越來越多，又以液晶顯示器為主流，成為了生活中不可或缺的產品。 在眾多顯示器技術裡，其中FFS(Fringe-field switch)技術具有廣視角、高亮度等優點，在過去研究針對正型液晶驅動之2D VAFFS與負型液晶驅動之3D VAFFS深入分析時，發現結構中產生之向錯(Disclination)能夠加快反應時間，向錯即為虛擬牆，又以改變電極結構設計，使虛擬牆能夠在長時間信號輸入下仍然存在且保持穩定，目前已有成效。 本論文將簡化井字式叉字形結構，使結構成為陣列式，整體更加均勻與規律，並分析兩者結構之液晶分子轉動情況，接著探討操作電壓、穩定性、反應時間與穿透率之關係，最後進行比較。由於先前畫素電極設計較為複雜，後續提出新型菱形結構，探討將電極設計更加簡化時能否提升穿透率、反應時間與穩定性，並且降低操作電壓，並且利用多種液晶材料進行模擬與比較，來了解結構之通用性。 菱形結構中液晶分子出現螺旋形式轉動，我們將此結構進行優化，增加電極間隙，控制電場之強度，並在共同電極上也形成虛擬牆，使整體反應時間更快速，接著分析液晶分子轉動情形，與探討新結構之操作電壓、穩定性、反應時間與穿透率，最後與優化前進行比較。

With the development of technology, people spend a lot of time on displays every day. From cell phones to TV and store window screens etc., many displays are being used in our daily lives. This shows that there is an increasing demand for displays. Liquid Crystal Display (LCD) is the mainstream display technology, and has become an indispensable product in our lives. The fringe-field switch (FFS) technology is one of the various LCD display technologies available. It offers benefits including wide viewing angle and high transmittance. From previous research such as 2D VAFFS driven by positive liquid crystal and 3D VAFFS driven by negative liquid crystal, it was found that the disclinations created within the structure can help improve the device’s response time. This disclination is also known as the virtual wall. These virtual walls can be stable even under a long-time signal input by altering the electrode structure's design. This approach has proven to be effective so far. In this thesis, the previously proposed cross-structure design will be simplified into a more uniform and regular array structure. We will analyze the liquid crystal molecular rotation on these two structures, and also investigate the relationships between transmittance, operating voltage, stability and response time, and finally provide a comparison between them. In this thesis, a new diamond-structure is also proposed in order to explore the possibility of further simplifying the electrode design while maintaining similar transmittance, stability, response time and operating voltage. Additionally, different liquid crystal materials were used in the simulations for the comparison of these different structure designs. Finally, in order to improve the response time, we further optimized the diamond structure by widening the gap between the electrodes, adjusting the electric field strength and creating a virtual wall on the common electrodes such that liquid crystal molecules' spiral rotation may be minimized. We analyzed the molecular rotation of the liquid crystals in these new structures and also investigated their performances on operating voltage, stability, response time, and transmittance. Finally, we also compared the results of these new optimized structures with the pre-optimized structures.