A new low-voltage electrically-addressed bistable nematic liquid-crystal boundary-layer display

A method of electrical switching between the bistable states of a recently reported display is described [p. 1007, [5]]. The topologically-equivalent bistable states have boundary-inversion (BI) layers adjacent to one or the other of the cell surfaces. The display allows low-voltage operation, is capable of good contrast, and is relatively insensitive to changes in material parameters, boundary conditions, and temperature. In the described method of switching, the state is selected by the height of an ac switching voltage in a suitably fabricated asymmetrical cell. A low switching voltage, by a process that is uniform over the pel area, quickly produces the state with the BI layer at the surface favored by the cell's asymmetry. A somewhat higher voltage produces the other state by a domain wall slowly shrinking from the pel perimeter. The write time (uniform process) can be as short as 50 ms, but the erase time (domain wall motion) is more than a second.