邊際電場對單間隙半穿反液晶顯示器之影響

Influence of Fringing Field on Single Cell Gap Transflective LCDs

周孟輝(Mong-Hui Chou)

指導教授 ： 徐芝珊

中原大學/理學院/物理研究所/碩士(2011年)

https://doi.org/10.6840/cycu201100973

摘要

我們利用耦合電容的方法（CC type，Coupling Capacitance type），即是在穿透區之畫素(Pixel)電極與反射區的畫素電極間耦合一個電容，使外加電壓於穿透區畫素電極時，反射區電極能感應出較低之電壓。當光通過穿反兩區液晶時，可得到相同的相位延遲。量測、分析並優化由垂直排列之液晶模態設計出的單間隙CC type的半穿反式液晶顯示器（Single-mode-type single-cell-gap transflective LCDs）。
　　在分析評估半穿反式液晶顯示器的影像品質上，我們採用（Gamma標準差）值作為影像品質好壞的依據：若值越小，則穿反兩區之Gamma曲線越匹配，此半穿反式液晶顯示器的影像品質越好。首先，我們對一維液晶模擬程式所設計出的CC type半穿反液晶顯示器面板進行值的分析，其結果優於模擬的預期。分析其原因是因為一維模擬軟體不能模擬出電極之間邊際電場（Fringing-Field）的影響。我們改用LCD Master之二維液晶模擬軟體分析此設計：其模擬之面板Gamma標準差果真較接近實驗所量測到的值。
　　藉由調整耦合電容的大小、考慮邊際電場效應、改變反射區電極長度之比例與在反射區共電極加上一適當電壓（Dual common & Coupling capacitance，DCCC type），成功的使值降低，優化了垂直
排列液晶模態之單間隙半穿反式液晶顯示器。

關鍵字

半穿反液晶顯示器 ； Gamma標準差 ； 雙共電極 ； 耦合電容

並列摘要

We use the Coupling Capacitance type (CC type) method, which is adding a coupling capacitance between the transmissive and reflective part to induce a lower voltage in the reflective pixel electrode when we apply a voltage on the transmissive electrode. Thus, when light pass through the liquid crystal layer, the phase retardation of the light obtained in these two areas will be the same. The measurement, analysis and optimization of a CC type single-LC mode, single-cell-gap vertically aligned (VA) transflective LCD design will be discussed.
　　We adopted value (standard deviation of Gamma curve) to evaluate the image quality of LCD. The smaller the value, the better image quality of the LCD will exhibit, which is the consequence of the two matched Gamma curves of the transmissive and reflective areas. In the first part, we measured the  value of a CC type transflective LCD designed by using one-dimensional (1D) liquid crystal simulator. The value was smaller than we expected. Through some studies we realized that the disagreement was resulted from the Fringing-Field effect. Later, we used two-dimensional (2D) liquid crystal simulator (LCD Master) to confirm our analysis.
　　To optimize the design, we adjusted the values of the capacitance; reduce the length of the reflective electrode and even adding a proper voltage in the common electrode, that is, we modified it into a dual common & coupling capacitance design. The value of the VA transflective LCD was successfully reduced.

並列關鍵字

Coupling Capacitance ； Dual Common ； standard deviation of Gamma curve ； transflective LCD

參考文獻

[1] X. Zhu, Z. Ge, T. X. Wu, and S.-T. Wu, “Transflective Liquid Crystal Displays,” IEEE, pp. 15–29, (2005).

[2] C.-L. Yang, I-A. Yao, W.-Y. Ling, P.-F. Wang, C.-J. Chen, and J.-P. Pang, “A Transflective OCB LCD with Wide Viewing Angle and Fast Response,” SID 05 Digest, pp. 1876–1879, (2005).

[3] C.-L. Yang, “Electro-Optics of a Transflective Liquid Crystal Display with Hybrid-Aligned Liquid Crystal Texture,” Jpn. J. Appl. Phys., 43, pp. 4273–4275, (2004).

[5] C.-J. Yu, J. Kim, D.-W. Kim, and S.-D. Lee, “A Transflective Liquid Crystal Display in a Multimode Configuration,” SID 04 Digest, pp. 642–644, (2004).

[6] J.-H. Park, C.-J. Yu, J. Kim, S.-Y. Chung, and S.-D. Lee, “Concept of a liquid-crystal polarization beamsplitter basedon binary phase gratings,” Appl. Phys. Lett., 83, pp. 1918–1920, (2003).