Improving Color Tracking in In-Plane Switching Mode Liquid-Crystal Displays

Color tracking describes the ability of a display to faithfully reproduce the color quality of the source image. In liquid-crystal displays (LCDs), color tracking is dependent on brightness. In order to achieve high-performance color reproduction in LCDs, the accuracy of color tracking needs to be improved. By analyzing the characteristics of twisted-nematic (TN) and in-plane switching (IPS) modes of display, the cause of poor color tracking in each mode and the differences in their causes can be clarified. In TN mode displays, both chromaticity and brightness relate to the director configuration, that is, the directional alignment of the rod-like molecules of the liquid crystals, which varies with applied voltage. The ideal IPS LCD, by virtue of its operating principle, theoretically achieves perfect color tracking; however, in actual use, the color tracking is less than optimal due to twist deformation caused by the fixed directors on the alignment layer. Based on our analysis of these phenomena, we propose strategies for improving color tracking in IPS LCDs.