UV MODIFICATION OF SURFACE PRETILT OF ALIGNMENT LAYERS FOR MULTIDOMAIN LIQUID-CRYSTAL DISPLAYS

Two types of ultraviolet (UV) light induced modification of the surfac e pretilt of alignment layers are reported. The UV modification allows the liquid crystal (LC) surface pretilt angle of a polyimide film to be selectively altered in a small area. Two device structures for fabr icating two-domain liquid crystal displays based on this selective alt eration of the LC surface pretilt angle of polyimides are proposed. Re sults from 3D simulation show that each pixel splits into two domains for the proposed structures. Experimentally, two-domain twisted nemati c (TN) test panels and thin-film-transistor (TFT) addressed two-domain TN panels were fabricated using this method. The UV modification desc ribed in this letter does not require conventional photoresist technol ogy as do other methods of fabricating two domain liquid crystal displ ays (LCDs). This process is simple as it requires only one polyimide c oating and one rubbing step for each substrate. (C) 1995 American Inst itute of Physics.