Depolarization effect in liquid crystal displays

We develop a rigorous model to simulate an LCD's contrast ratio (CR) and viewing angle by considering the depolarization effect in thin-film transistor substrate, LC layer, color filter (CF) array, etc. To mitigate the depolarization effect, we propose a new device structure by adding a thin in-cell polarizer between LC layer and CF array. Based on the analysis using our new model, the maximum CR of a multi-domain vertical alignment (MVA) LCD can reach > 20,000:1, while for the fringe-field switching (FFS) mode it can reach > 3000:1. We also discuss other approaches to further enhance the CR. Our model is a powerful tool to analyze the CR degradation mechanism and to guide the future LCD device and material optimizations.