Light Behavior Analysis of Twisted Nematic Liquid Crystal Display

Abstract

We investigated the light behavior in a twisted nematic (TN) cell by plotting the polarization and liquid crystal director on a Poincaré sphere. We calculated the polarization using Berreman's 4×4 matrix method. We have clarified (1) the polarization of light propagating in a liquid crystal layer for oblique viewing in upper, lower, right, and left azimuth, (2) the reason for each oscillation and peak of transmittance–voltage characteristics at oblique viewing angles, (3) the reason for the difference between the viewing angle characteristics of e-mode and o-mode TN-LCDs, and the reason why e-mode and o-mode TN-LCDs have the same characteristic in some azimuth, (4) the reason why normally black mode does not have symmetrical viewing angle characteristic.