Development of a software for analyzing thin film flow of liquid crystals for the purpose of high efficiency of liwuid crystal display manufactureing

注塑工艺是制造液晶显示器(LCD)的重要工艺之一。本研究项目的目的是开发一个广泛使用的能够对注射过程进行数值预测的软件。该软件可以大大缩短任意尺寸和形状LCD的注射时间，提高生产效率，降低成本。选择Leslie Ericksen方程作为液晶流的本构方程，对运动方程和本构方程进行Hele Shaw近似。采用有限差分法对控制微分方程组进行离散。根据分子取向的不同，液晶有三种粘度。我们用流变仪测量了在外场强迫分子定向到所需方向的条件下的粘度。还测量了液晶的表面张力。VIE进行了注入实验，测量了注入时间和自由表面位置的时间序列，并用该软件模拟了几种典型计算条件下液晶注入液晶盒。结果表明，该软件可以预测液晶在池中的平稳流动，并阐明了注射孔大小、池间隙和注射压力对注射时间的影响。研究还发现，具有两个注入孔的液晶盒的注入时间比具有单个但两个面积注入孔的液晶盒的注入时间要短。然而，预测与实验并不一致。这是因为在注射过程中，由于细胞内外的压力差，细胞间隙变得比初始细胞间隙小。

Injection process is one of the most important processes for manufacturing liquid crystal displays (LCD). The purpose of this research project is to develop a widely usedsoftware which can predict numerically the injection process. Such the software makes possible to reduce greatly the injection time for LCD with arbitrary size and shape, leading to high productivity and to a decrease in cost.The Leslie Ericksen equation is selected as a constitutive equation for liquid crystalline flow, and the Hele Shaw approximation was made for both the equation of motion and the constitutive equation. Finite difference method was employed to discretize the governing differential equations. Liquid crystals have three kinds of viscosities depending on molecular orientation. We have measured the viscosities by using a rheometer under conditions that molecules were forced to orient to required directions by an external field. Surface tensions of liquid crystals were also measured. Vie did injection experiments and measured the injection time as well as a time series of free surface locations.We used the software to simulate injection of liquid crystals into liquid crystal cells under some typical computation conditions. As a result, the software could predict smooth flow of liquid crystals in the cells, and effects of injection hole size, a cell gap, and injection pressure on the injection time were clarified. It is also found that the injection time for a liquid crystal cell with two injection holes becomes short compared to that for a cell with single but twice area injection hole. However, the predictions did not agree with experiments. This stems from the fact that the cell gap during injection becomes smaller than the initial cell gap because of the pressure difference between in and out of the cell.