Modeling and measuring the effects of domain walls in liquid crystal displays

In many applications, the presence of domain walls limits the performance of liquid crystal displays (LCDs) in terms of brightness, contrast and response speed. Examples are found in wide-viewing-angle LCDs in which each pixel contains domains with different director orientations. Microscope measurements of various types of LCDs are presented and compared with the results of advanced two- and three-dimensional simulations. The background of the modeling programs is reviewed, especially if new methods are used. One example is that of a double-domain twisted-nematic (TN) LCD configuration that was made using photo-alignment. The shape of the domain wall and its effect on the transmitted intensity are described correctly by simulations. In another example it is shown that the experimental results for in-plane switching (IPS) structures can be understood with the help of advanced optical simulation methods that take into account diffraction effects. In a final example, the occurrencc of domain walls in liquid crystal on silicon (LCoS) is discussed.