US Patent 7670654 Bistable liquid crystal display device

A bistable nematic liquid crystal display device includes two cell walls enclosing a layer of a nematic liquid crystal material, means for applying an electric field across at least some of the layer, and means for inducing local planar alignments of said liquid crystal material at an inner surface of each cell wall. The local planar alignments are oriented to each other at an angle greater than 0° and less than 90°. The device also includes means for selectively masking an alignment effect of either of the local planar alignments by applying a unidirectional electric field pulse of suitable magnitude and duration to stabilise the device in one of two different homeoplanar configurations determined by the polarity of the pulse.