碰觸力作用於顯示器之液晶動力學

Abstract

液晶分子的動態行為在液晶光學的研究中是有趣的課題。液晶的動態特性不僅與液晶的材料性質、電場、磁場有關，液晶顯示器的畫面受到碰觸力作用，也會產生宛如漣漪的傳播。本研究之貢獻在於首先探討碰觸力作用下的液晶動力學。由於向列型液晶可以像一般液體自由流動，因此液晶的流動和液晶分子的轉動是相互耦合的。本研究根據黏彈理論與Ericksen-Leslie理論發展理論模式，針對向列型液晶探討漣漪現象的原因。由黏彈理論結合波動方程式，推導出一個統御方程式探討碰觸力大小對液晶量多寡的影響。實驗結果顯示，每個面板不隨著碰觸速度改變波傳速度，而且液晶量較多的面板的波傳速度較慢。以Ericksen-Leslie理論為基礎，推導碰觸力對液晶分子轉動的理論公式，其正確性以解析解驗證，並且改變液晶的材料與參數，探討影響液晶傾角的因素。

The dynamic behavior of LC molecules is an interesting phenomenon among liquid crystal optical responses. The dynamics of LCs is related not only to material properties of LCs, electric field, and magnetic fields. Ripple-like expansion is observed when displays are subject to tactile forces. This dissertation contributes to liquid crystal dynamics subject to tactile forces. Since nematic LCs can flow as easily as an isotropic fluid, there is a coupling between the translational motion and molecule's rotation of LCs. According to the visco-elasticity theory and the continuum theory of Ericksen-Leslie, this study constructs theoretical models for nematic liquid crystals in order to investigate the cause of ripple propagation. The governing equation is derived by using visco-elastic and wave equations. Experimental results show that each display panel has its own wave propagation velocity, which is not changed by different touch speeds. In addition, displays with a larger amount of liquid crystals lead to slower ripple speed. Based on the Ericksen-Leslie theory, tactile-force effects are taken into account to derive the molecule equation of motion for LCs. The comparison results show that analytical solutions are consistent with numerical solutions. Finally, factors that affect tilt angles are investigated for different LC materials and coefficients.