邊際電場對於矽基型液晶顯示器(LCoS) 灰階特性之影響

Abstract

矽基型液晶顯示器(LCoS)廣泛的使用在大尺吋投影顯示器以及頭戴式顯示器方面。它的主要優點是組裝緊密、輕巧、高亮度以及優良的顯示品質。由於高解析度顯示的要求，所以畫素的必須要儘量縮小，但是伴隨而來的就是液晶會受到邊際電場的影響。當一個畫素和鄰近畫素間驅動電壓不同時，邊際電場就會存在，液晶分子就會受到原先設計的縱向電場以及邊際電場加成效應的影響。隨著驅動方式的不同，邊際電場會偏轉液晶分子到與原來設計的方向不同的地方。 我們建立了一些實驗裝置來研究在不同驅動方式，相異液晶模態以及畫素間距條件下，邊際電場對於LCoS顯示器灰階顯示的影響。我們利用拍攝照片，量測對比度以及響應速度的方式來評估LCoS顯示器的靜態以及動態特性。最後我們將會找出最適用於LCoS的液晶模態以及驅動方式。 在實驗結果之中，我們發現VA和MTN 80∘是表現較佳的液晶模態，而Frame Inversion是最好的驅動方式。另外在邊際電場影響下，增加畫素間距對於整體效能並沒有太大的改善。

Liquid-Crystal-on-Silicon (LCoS) has wide applications in large screen projection display and head-mount display. Compact, light-weight, high brightness ,and high image quality are its major advantages. With the demand for higher resolution, the pixel size must be decreased and an accompanying crosstalk effect is resulted. Between the neighboring pixel electrodes with different voltages, there exists a fringe field in addition to the applied field. The liquid crystal molecules response to the superposition of the fringe field and designed field. Depending on the driving methods, the fringe field will deviate the LC directors into different directions from that of designed field. An apparatus was built in order to study the influence of fringe field on the display of gray levels of LCoS cell in various LC modes、driving methods and different inter-pixel gaps. We take photographs and measure contrast ratio and response time to evaluate the static and dynamic properties of LCoS samples.In the end, We determine what is the better mode and driving method for the LCoS panel. In our results of simulation and experiments,we find VA and MTN 80∘have better performance than others, and frame inversion is the best driving method.Increasing inter-pixel gap doesn’t improve gray-level properties much under fringe field effects.