Physical Model of Pixels in Twisted Nematic Active-Matrix Liquid Crystal Displays

In this paper, we propose a new physical model to predict the transient responses of an active-matrix liquid crystal display (LCD) in a twisted nematic (TN) mode. For the behavioral model, three types of data are most important: 1) capacitance-voltage; 2) transmittance-voltage characteristics; and 3) time constant parameters a1 and a2. We extract them from the physical properties of TN LC molecules, such as dielectric anisotropy, birefringence, viscosity, cell gap, and elastic constant. We describe the behavior of the TN-LCD by using the analog hardware description language, Verilog-A. We simulate optically rising responses of the TN-LCD panel by importing the behavioral circuit model in the circuit simulator. The simulation results show that the transient optical responses show excellent matches with the measurement ones. In addition, we can observe how the behaviors of optical responses change with varying the physical parameters, such as cell gap, dielectric anisotropy, and elastic constant.