Development of Multiple-functional, Cost-effective Liquid-crystal Cell Optical Parameter Measurement Systems

[[abstract]]For years, the government has promoted the “Two Trillion and Twin Star Industries Development” plan. As a result, the flat panel displays (FPDs) had become one of the most important industrial applications. For example, the FPDs in Taiwan occupied 63% (about $NT 7,141 hundred million dollars) of the optoelectronics industry in Taiwan and 31% in the market of the FPDs in the world in 2005. Therefore, to promote effectively the output and quality of the FPDs, it is very urgent to research and develop the LC cell optical parameter measurement systems. The objective of this paper is to develop a multiple-function and cost-effective measurement system to lower the dependency of foreign instrument makers and to reduce the manufacturing cost for the industry. In the paper, we first study the past approaches and analyze their measurement performance. Then, a simple and cost-effective method will be proposed to achieve the multiple functions. This system on the basis of the PSCA configuration uses the crystal rotation method to measure the pretilt angle of the sample under test, and the polarimetry to measure the cell gap and twist angle of it. These optical parameters highly influence the display quality. That is, in addition to the measurement of the three important optical parameters, this system can also measure the voltage-transmittance (V-T) curve. For this system, we will do the theoretical study, simulation, experiment, system implementation to show its feasibility. From the experiment results, it is shown that the measured results were quite satisfactory. For example, the error percentage was 1.45 %.