Study on the pixel voltage of TFTLCDs with optical measurement

Abstract

The image quality of a TFTLCD is dependent on the voltages on the pixel electrodes, which can be influenced by many factors, such as coupled voltage from scan bus and leakage current of TFT. However, it is difficult to directly probe the pixel voltage electrically. Therefore, measuring the transmittance of the LCD is very helpful to characterize a panel. Looking up the transmittance curve of the liquid crystal cell, the voltage on the pixel can be retrieved. However, the liquid crystal can not respond the pixel voltage in real time and thus such a method may not be used at video frequency. In this paper, various applications of the optical measurement to study the coupled voltage and leakage of pixel electrodes in a TFTLCD are discussed.