ELECTROOPTIC CHARACTERISTICS AND SWITCHING PRINCIPLE OF A NEMATIC LIQUID-CRYSTAL CELL CONTROLLED BY FRINGE-FIELD SWITCHING

We have fabricated a nematic liquid crystal cell associated with a hom ogeneously aligned to twisted transition of a liquid crystal director. In the absence of an electric field, the liquid crystal molecule is h omogeneously aligned under the crossed polarizers, and thus the cell a ppears to be black. When a fringe field induced by interdigital electr odes is applied, liquid crystal molecules rotate in plane even above e lectrodes and thus the cell transmits light. The device exhibits a hig h transmittance ratio as well as a wide viewing angle, which solves a long standing problem of low transmittance existing in the conventiona l in-plane switching mode. We show that the distance between electrode s smaller than the width of an electrode and cell gap is required for generating fringe field with applied voltage and rotating molecules ab ove electrodes. We also investigate the mechanism of fringe-field swit ching and dependence of electro-optic effect on different cell conditi ons and dielectric anisotropy of liquid crystal. (C) 1998 American Ins titute of Physics. [S0003-6951(98)04346-0].