液晶盒反射谱用于盒厚测量的研究

【作者】 杨玉成；

【导师】 黄子强；

【作者基本信息】 电子科技大学 ， 光学工程， 2007， 硕士

【摘要】 在液晶显示屏的制造过程中,液晶盒的厚度和尺寸一般都要进行严格选择,以便使液晶层的厚度达到设计要求,保证液晶显示器所要求的特定显示模式的实现,例如,扭曲向列液晶显示模式(TN工作模式)、超扭曲液晶显示模式(STN工作模式)、电控双折射模式(ECB工作模式)等,从而能够实现正常的显示效果。具体来说,液晶盒厚度对液晶显示器性能的影响主要体现在以下两个方面:第一,为了获得高对比度、高亮度、高响应速度的显示效果,液晶显示器盒厚的精度必须控制在0.1μm以下,特别是彩色超扭曲向列相液晶显示器( CSTN- LCD),对盒厚的精度要求更高,一般必须控制在±0.05μm以下。第二,液晶显示器盒厚的均匀性对于其显示均匀性也有着至关重要的作用。如果盒厚不均匀,便会引起液晶显示器底色变化,造成颜色废品,特别是在彩色超扭曲向列相液晶显示器制造过程中,对液晶盒厚的均匀性要求更高,该技术的关键之一就是精确控制液晶盒的厚度。本文研究了一种新型的液晶盒厚度测试技术——反射光谱极大值优化拟合法。该技术实现了以白光作为前端光源照射液晶盒,通过测量液晶盒的反射光谱来获得盒厚的信息。在实验中,前端光纤光谱仪主要用于测试反射光谱,光纤光谱仪通过USB接口,将反射光谱及其对应的测试数据传输到计算机中,通过对反射光谱的分析、优化拟合最终得出被测液晶盒厚度。本方法的优点是:测量数据处理过程完全程序化,液晶的物理性质、琼斯矩阵相关的公式推导及其光学相关的复杂公式与测量过程关系不是很大,测试人员可以更容易得到测试结果。本文以生产线上常见的6μm厚的液晶盒为测试对象,采用光干涉法、反射光极值拟合法两种方法对液晶盒进行对比测试,以确定其精度。结果证明,反射光极值优化拟合法测量的重复误差为0.1μm左右,测量范围5μm至30μm,测量时间在1秒以下,有较强的实用价值。更多还原

【Abstract】 In the productive procedure of LCD, in order to make LC layer satisfy the requirement of design and guarantee the complement of LCD special display mode, the thickness and size of LCD is usually seriously controlled. Those modes, for example, include Twisted Nematic LC display mode(TN working mode), Super Twist Nematic mode(STN working mode), Electronic Controlled Bi-refraction mode(ECB working mode) and so on. For the detail, the main effect of the thickness of LCD for the LCD’s performance includes the following two aspects: First, for the higher contrast ratio, response speed, luminous, LCD gap’s precision must be controlled under 0.1μm. Especially, the precision requirement of Colorful STN-LCD is more serious, and it must be under±0.05μm. Second, the LC cell’s thickness regularity is vital important for the displaying regularity. If the LC cell is not regular, it could cause change of LCD’s color and make the cell into fake. Especially in the process of STN-LCD manufacturing, the key technology is controlling the thickness of LCD gap.In this dissertation a new thickness measurement technology of LCD gap has been researched. This technology is based on the max value of reflective light intense and use the optimal fitting method to get the final measurement value. This method use the white light as the light resource, through relationship between wavelengths and the reflective light intense to obtain measured LCD gap’s relative data information. The measurement data will be stored in PC through USB interface. After data process, LCD’s thickness could be received directly. The benefit of this measurement method is that the procedure of measument data is fully programmable, and operator could get the result without understanding LC physic feature,complex formulations of Jones Matrix and optic principle.The measurement objective is 6μm LCD gap which is widely used. Through comparing the methods of spectral interference and max value fitting, the advantage and disadvantage between two measurement methods is self-proof. The result has shown that this difference could be controlled under 0.1μm by using the max value fitting method , the measurement scope is between 5μm and 30μm, and measurement exhausting time is under 1 second. This measurement technology could be well used in the process of LCD manufacturing.更多还原