MEMORY EFFECTS IN NEMATIC LIQUID-CRYSTALS BY A SURFACE MOLECULAR-REORIENTATION

A liquid crystal cell with an asymmetric electrode structure is prepared by using a slit-patterned or a hole-patterned electrode and an unpatterned counterelectrode. Only the surface of the latter substrate is treated by rubbing. When the liquid crystal cell is once heated up to an isotropic phase and then cooled down to a nematic phase with a sufficiently high electric field, a memory effect of the molecular orientation along a lateral component of a nonuniform electric field, which is produced by the patterned electrode structure, is observed after removing the electric field. This memory state can be erased by heating the cell up to the isotropic phase and it can be reproduced repeatedly. These phenomena are discussed in terms of the molecular orientation effects on the surface of an alignment layer without rubbing treatment.