Author Affiliations
Abstract
1 School of Sciences, Hebei University of Technology, Tianjin 300401, China
2 School of Physical Science and Technology, Southwest University, Chongqing 400715, China
3 Hebei Jiya Electronics Co., Ltd., Shijiazhuang 050071, China
4 Hebei Provincial Research Center of LCD Engineering Technology, Shijiazhuang 050071, China
Image sticking in liquid crystal display (LCD) is related to the residual direct current (DC) voltage (RDCV) on the cell and the dynamic response of the liquid crystal materials. According to the capacitance change of the liquid crystal cell under the DC bias, the saturated RDCV (SRDCV) can be obtained. The response time can be obtained by testing the optical dynamic response of the liquid crystal cell, thereby evaluating the image sticking problem. Based on this, the image sticking of vertical aligned nematic (VAN) LCD (VAN-LCD) with different cell thicknesses (3.8 μm and 11.5 μm) and different concentrations of γ-Fe2O3 nanoparticles (0.017 wt.%, 0.034 wt.%, 0.051 wt.%, 0.068 wt.%, 0.136 wt.%, 0.204 wt.%, and 0.272 wt.%) was evaluated, and the effect of nano-doping was analyzed. It is found that the SRDCV and response time decrease firstly and then increase with the increase of the doping concentration of γ-Fe2O3 nanoparticles in the VAN cell. When the doping concentration is 0.034 wt.%, the γ-Fe2O3 nanoparticles can adsorb most of the free impurity ions in liquid crystal materials, resulting in 70% reduction in the SRDCV, 8.11% decrease in the decay time, and 15.49% reduction in the rise time. The results show that the doping of γ-Fe2O3 nanoparticles can effectively improve the image sticking of VAN-LCD and provide useful guidance for improving the display quality.
nanoparticles doping image sticking SRDCV response time VAN-LCD Chinese Optics Letters
2020, 18(3): 033501
为了通过实验得到向列相液晶材料的双折射率，利用迈克尔逊干涉原理设计了一种新的测量方法。在迈克尔逊干涉仪中放入楔形液晶盒，通过调节入射光的偏振方向分别实现了对寻常光和非寻常光折射率的精确测定。结果表明，该测量方法将折射率测量转换为长度的测量和干涉条纹的计数，简单易行、测量精度较高，对理论研究和实际开发液晶显示器件是非常重要的，在液晶材料和液晶器件生产中具有一定的推广价值。
测量与计量 双折射率 迈克尔逊干涉原理 向列相液晶 楔形液晶盒 measurement and metrology birefringence Michelson interference principle nematic liquid crystal wedge-shaped liquid crystal cell
1 中国科学院长春光学精密机械与物理研究所，应用光学国家重点实验室, 吉林 长春 130033
2 中国科学院大学， 北京 100049
3 河北工业大学理学院, 天津 300401
4 河北冀雅电子有限公司, 河北 石家庄 050071
基于自组装的液晶动态响应实验装置，研究了液晶挠曲电效应对强锚泊混合排列向列相（HAN）液晶动态响应过程的影响。实验中HAN 液晶盒施加脉宽为250 ms、幅度可调的正负单脉冲电压信号，结果发现：幅度相同的正负脉冲电压信号作用下液晶的动态响应不同，幅度不同的正脉冲或负脉冲电压信号作用下液晶的动态响应也不同。通过幅度不同的正脉冲电压信号（3、4、5、6 V）作用下液晶动态响应实验曲线与考虑挠曲电效应情形下液晶动态响应理论曲线之间的比较，得到了液晶材料E7的挠曲电系数为e11+e33=4.0×10-11 C/m，与文献中报道的实验测量值基本一致。
测量 混合排列向列相 动态响应 挠曲电效应 单脉冲 脉宽
基板的锚定特性，包括锚定能大小和锚定易取方向，影响液晶指向矢的分布，直接导致液晶盒电容的改变，因此可以通过液晶盒电容的测量确定基板表面的锚定特性。基于液晶弹性理论和变分原理，理论推导弱锚定平行排列向列相和混合排列向列相液晶盒系统的平衡态方程和边界条件，采用差分迭代方法数值模拟得到了液晶盒约化电容随电压、锚定能系数及锚定易取方向变化的曲线。结果表明：液晶盒电容随基板锚定能系数的增加而减小;随预倾角的增加，液晶盒电容随锚定能系数的变化缩小;同一电压和基板锚定能系数下，平行排列向列相液晶盒电容不会大于混合排列向列相液晶的电容。
液晶盒电容 锚定能 易取方向 弱锚定 差分迭代方法 capacitance of liquid crystal cell anchoring energy easy direction weak anchoring finite difference iterative method
1 中国科学院长春光学精密机械与物理研究所应用光学国家重点实验室, 吉林 长春 130033
2 中国科学院大学, 北京 100049
3 河北工业大学理学院, 天津 300401
强锚泊混合排列向列相(HAN)液晶盒中，挠曲电效应会对液晶指向矢分布产生影响，这种变化可以通过改进的液晶全漏导模技术实验进行测量。基于液晶多层光学理论和液晶弹性理论，计算得到强锚泊混合排列向列相全漏液晶波导反射率和透射率随内角（光线射入液晶层的角度）的变化曲线，分析了挠曲电效应的影响。挠曲电系数取符号“-”或“+”，全漏液晶波导反射率或透射率变化曲线相对于不考虑挠曲电效应时右移或左移一段距离，并且挠曲电系数数值不同移动的距离也会发生变化。由移动距离可知挠曲电系数的数值，为实验确定挠曲电系数提供了理论依据。
材料 全漏导模技术 挠曲电效应 多层光学理论 弹性理论 混合排列向列相
Author Affiliations
Abstract
We present a theoretical calculation of the dependence of reflectivity Rpp of the improved fully leaky waveguide geometry, which comprises pyramid, matching fluid, and strongly anchored hybrid-aligned nematic liquid crystal (NLC) cell on the internal angle. The calculation is based on the multi-layer optical theory and the elastic theory of liquid crystals. For different sums of flexoelectric coefficients e11 and e33, the curve of Rpp moves a distance to the left or the right relative to the case of ignoring the flexoelectric effect and the distance of the movement varies with different flexoelectric coefficients. Consequently, the sum of flexoelectric coefficients can be explored by measuring the distance of the movement.
230.3720 Liquid-crystal devices 230.7390 Waveguides, planar Chinese Optics Letters
2012, 10(5): 052301
Author Affiliations
Abstract
1 School of Sciences, Hebei University of Technology, Tianjin 300401, China
2 School of Information Engineering, Hebei University of Technology, Tianjin 300401, China
3 Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China
4 Graduate University of Chinese Academy of Sciences, Beijing 100049, China
5 Department of Mathematics and Physics, North China Electric Power University, Baoding 071000, China
Liquid crystal in a nematic liquid crystal cell surface with two crossed-grating surface substrates can be oriented along the normal grating direction with given geometric parameters of groove and anchoring strength. This display is equivalent to multi-domain vertical-alignment mode. It has a relatively wide viewing angle. In this letter, we investigate the viewing angle characteristics of this kind of cell. The viewing angle dependence of contrast ratio is obtained using the extended Jones matrix method, which also considers the flexoelectric effect. The viewing angle is dependent on the geometric parameter of grating surface, the flexoelectric coefficients, and the anchoring strength. Therefore, appropriate value for each factor needs to be selected to obtain a better viewing angle of this cell.
视角特性 栅状表面 多畴垂直显示模式 扩展琼斯矩阵方法 挠曲电 230.3720 Liquid-crystal devices 230.2090 Electro-optical devices Chinese Optics Letters
2010, 8(12): 1171
