Liquid crystal display incorporating positive and negative smectic material

摘要

A liquid crystal display cell provides more than two contrasting colors that operates in a storage mode which has a positive dielectric anisotropy smectic liquid layer between electroded plates treated to produce parallel homogeneous alignment with a very large tilt angle. The tilt angle can be progressively increased by increasing the strength of an applied alternating potential thereby producing Newtonian colors when viewed through crossed polarizers. When pseudo-homogeneous zero tilt alignment is provided, a pleochroic dye may be mixed with the smectic to provide a color when the layer is in the pseudo-homogeneous alignment state. An applied electric field converts this to homeotropic alignment. When a negative dielectric anisotropy smectic liquid layer is sandwiched between electroded plates treated to induce homeotropic alignment, application of an electric field turns the display from clear (black between crossed polarizers) to milky as the alignment changes from homeotropic towards homogeneous (metastable) degenerating to focal-conic.