Mechanically bistable liquid-crystal display structures

This paper discusses two types of mechanically bistable liquid-crystal display structures, a previously reported type [2], [3] called vertical-horizontal, and a second type, called horizontal-horizontal. In both of them, the director configuration is planar. They are distinguished by the orientation of the director plane, which is perpendicular to the major surfaces of the device in the type called vertical-horizontal, and parallel in the type called horizontal-horizontal. In both types, the bistable states may be differentiated optically by use of a polarizer and dichroic dye, and switching is accomplished electrically by exploiting the dielectric anisotropy of the ordered liquid crystal states. We show calculations of the director configurations, their energy, and optical contrast of the bistable states. The bistable states are topologically distinct, so that the switching transitions are necessarily discontinuous in character. The movement of disclinations governs the switching process, and their detachment forms the basis of stability.