Effects of Pretilt Angle on Electro-Optical Properties of Optically Compensated Bend Liquid Crystal Devices With a Mixed Polyimide Alignment Layer

The effects of pretilt angle on electro-optical properties of optically compensated bend liquid crystal cells with a mixed polyimide alignment layer are investigated. By adjusting the mixed polyimide concentration, several kinds of alignment layers are produced, and a wide range of pretilt angles $(2^{\circ}-66^{\circ})$ are achieved. Differing from the conventional addresses, the maximum-light-transmittance voltage, obtained from the transmittance–voltage curve of the cell undergoing the reverse measurement, is employed, making a $\sim 14\%$ enhancement in the output transmittance. Compared to the 0-wt% cell, the 0.6-wt% cell with 16 $^{\circ}$ pretilt angle achieves $\sim 38\%$ and $\sim 50\%$ improvement in the rising-time and falling-time response, respectively.