Freedericksz transition of twisted nematic cells

A general formula for calculating the Freedericksz transition of twisted nematic liquid crystal cells has been derived by taking into consideration the following factors: unequal elastic constants and arbitrary dielectric anisotropy for the liquid crystal medium, and a general form of the anisotropic liquid crystal-to-substrate interfacial potential with negligible pretilt angle. The numerical computation of the threshold voltage as a function of the anchoring anisotropy has been demonstrated for two nematic mixtures. Increasing the degree of multiplexing of twisted nematic cells seems feasible using certain nematic mixtures with weak anchoring anisotropy.