Automatic LCD Electro-optical Characteristics Measurement System Based on Generalized Spectroscopic Ellipsometry

摘要

Liquid crystal displays (LCDs) or thin-film transistor (TFT) LCDs have been regarded as a promising technology in flat panel displays (FPDs). To meet the demands of the mass production and quality control, the development of automatic electro-optical characteristics measurement systems for LCDs is very important. To achieve this, we propose a generalized Spectroscopic ellipsometry (GSE) based technique to measure the characteristics of LCDs. Our approach involves two primary steps. First, we review a theoretical basis for generalized Spectroscopic ellipsometries for the LCD measurement. Those are mainly categorized into two classes of ellipsometries: the transmission variable angle Spectroscopic ellipsometry (VASE) and the Spectroscopic ellipsometry (SE) using a photoelastic modulator (PEM), called PEM SE. Second, on the basis of the VASE and PEM SE, we present a GSE-based system to measure the electro-optical characteristics for twisted nematic liquid crystals (TNLCs) and super twisted nematic liquid crystals (STNLCs). In this paper, the simulation results indicate the feasibility of this technique. Finally, the automatic GSE-based system is presented for measuring the LCD electro-optical characteristics.