高分子聚合物分散液晶的特性與其在抬頭顯示器和可調式共振腔的應用

Characteristics and application of polymer dispersed liquid crystal in head up display and tunable resonant cavity

侯舜齡(Shun-Ling Hou)

指導教授 ： 蘇國棟

共同指導教授 ： 蔡永傑

國立臺灣大學/電機資訊學院/光電工程學研究所/碩士(2013年)

https://doi.org/10.6342/NTU.2013.00889

摘要

液晶材料已被研究許久且應用在許多方面上，然而普通顯示器用的水平、垂直配向液晶等仍需要用到偏光片，這使得背光源的使用效率低。為了克服此問題，高分子聚合物分散液晶這種由液晶和高分子聚合物單體所組成的材料孕育而生。高分子聚合物分散液晶因其特殊的光電特性，不需要用到偏光片。此外，高分子聚合物分散液晶有著高對比跟不錯的反應時間，因此把高分子聚合物分散液晶應用在抬頭顯示器以及可調式共振腔上是可行的。
在論文第前三部分中，首先介紹液晶、製作過程以及針對高分子聚合物分散液晶本身特性以及各個可調參數作探討。例如: 液晶濃度、液晶盒厚度、照射紫外線強度…等。同時分析各個數據的優劣，並找出最適合應用在抬頭顯示器以及可調式共振腔的參數。
本論文第四部分利用前面所找出最適當的參數製作高分子聚合物分散液晶，應用在抬頭顯示器上。由於高分子聚合物分散液晶本身的良好特性，使得我們的抬頭顯示器可以有極高的光使用效率以及有高的對比。另外我們採用超高亮度LED模組當作背光源，以達到大白天也能看見清晰的影像的要求。
本論文第五部分則是利用高濃度的高分子聚合物單體所調製的高分子聚合物分散液晶來製作法布立－培若共振腔。我們想利用本身穿透率高、折射率可調以及反應速度快的特性，在共振腔內藉由給予不同的電壓來改變特定波長的穿透率(波長調變)，來彌補對比不足的缺點。

關鍵字

法布立－培若干涉儀 ； 高分子聚合物分散液晶 ； 液晶 ； 抬頭顯示器

並列摘要

Liquid crystal (LC) material has been investigated for a long time and has been applied to a variety of device. However, most of display, which uses vertical and planar alignment liquid crystal, still needs to utilize the polarizer. The light efficiency of back light source may suffer a lot from polarizer. In order to overcome this kind of problem, polymer dispersed liquid crystal (PDLC) which consists of monomer and liquid crystal was invented. Due to the unique E-O characteristics of PDLC, it doesn’t need polarizer to block the polarized light. Moreover, PDLC has high contrast ratio (CR) and quick response time. It’s feasible to apply polymer dispersed liquid crystal to head-up display (HUD) and tunable resonant cavity.
In chapter 1 and 2, we introduced the liquid crystals and fabrication process of PDLC. In chapter 3, we studied the characteristics of PDLC and the influence of parameters such as LC/polymer concentration, cell gap and UV intensity on PDLC. By comparing with the result of different parameters, we can obtain the most suitable parameter for fabricating head-up display and tunable resonant cavity.
In chapter 4, we applied the PDLC to HUD display application by using the optimized parameter that we found in the first part. Because of the good characteristics of PDLC, it can present high CR and high light efficiency. We also used the ultra-bright LED as a back light source so that the projected image can also be seen clearly in broad daylight.
In chapter 5, we utilized high polymer concentration PDLC to fabricate the tunable Fabry-Perot resonant cavity. Due to its high transmittance, tunable refractive index and fast response time, it can achieve wavelength tuning (or change transmittance for certain wavelength) in resonant cavity by giving different voltage. By using this method, it can help increasing contrast ratio.

並列關鍵字

polymer dispersed liquid crystal (PDLC) ； head-up display (HUD) ； Fabry-Perot cavity ； resonant cavity

參考文獻

[1] D. K. Yang and S. T. Wu, “Fundamentals of Liquid Crystal Devices”, Wiley, New York, 2006.

[2] D. K. Yang and S. T. Wu, “Reflective Liquid Crystal Displays”, John Wiley & Sons, 2002.

[8] P. S. Drzaic, “Liquid Crystal Dispersions”, World Scientific, N. J., 1995.

[9] J.W. Doane, “Polymer dispersed liquid crystal displays”, Vol.1, Chapter 14, Liquid crystals, applications and uses, 1990.

[10] Hyung Ki Hong, JaeKyeong Yoon, Moojong Lim, “Analysis of the dependence of optical response time of liquid-crystal display on the viewing direction”, Journal of the SID, 2008.