Cell panel electrical test for evaluating the electrical characteristics of liquid crystal displays

Abstract

Electrical models of liquid crystal display (LCD) have been studied and used in design simulation. Using the right LCD models is indispensable to accomplish high-quality and highly reliable LCDs. This paper presents a cell panel electrical test (Cell-E Test) for evaluating the electrical characteristics of LCDs. The Cell-E Test was derived from in-process electrical testing for thin film transistor arrays, and utilizes charge measurement for measuring the capacitance value of a pixel. The capacitance-voltage (C-V) and capacitance-time (C-t) characteristics can be measured using a sweeping-applied voltage and based on the period of applying voltage in the Cell-E Test. In this study, actual C-V and C-t characteristics were measured by applying the Cell-E Test to a twisted-nematic active-matrix LCD (TN AM-LCD). The parameters of liquid crystal models were extracted from the data measured using the least-squares method, to show that design models can be verified with the actual parameters of cell panels through the Cell-E Test.

Paper No P04: Assessment of Liquid Crystal Display Image Defects by Pixel Capacitance Measurement based on Electrical Model for Panel Design

“…However, the electrical model of LC panel is not used for inspection in the manufacturing process; visual inspection has been the main method for detecting image defects. In our previous work, highly accurate LC pixel capacitance test method utilizing measured electrical charge was introduced and implemented . In this article, effects of image defects on the electrical model are analyzed, and test method for assessing image defects in manufacturing process based on electrical models which are used for the design of LC cell panels is provided.…”