Abstract: An OCB device comprises upper and lower substrates, each provided with an alignment layer. A liquid crystal layer is provided between the substrates. The lower substrate has a low pre-tilt in regions A and C, so that an H-state is stable in these regions when no voltage is applied across the liquid crystal layer. Region B has a high pre-tilt on the lower substrate, so that a HAN state is stable in region B under zero applied voltage. When a voltage is applied across the liquid crystal lever, a V-state is formed at the interface between the HAN-state and the H-states. This V-state then displaces the H-states in regions A and C. The high pre-tilt region, region B, is acting as a nucleation region. The V-state forms at a lower applied voltage than if the nucleation region is not provided.

Abstract: A nematic liquid crystal device with two bistable switched states, having two cell walls treated which provide a bigrating on one or both cell walls. The bigrating enables the liquid crystal molecules at a surface to lie in two different angular directions, 45 or 90 degrees apart. The bigrating may be symmetric or asymmetric, with the surface energy of each of the gratings of the bigratings being nearly equal.