Drawing-Induced Biaxiality Change from a Positive C to a Negative A Plate and Its Application in Wide Viewing Angle IPS LCDs

摘要

Mechanical drawing is widely used to induce the optical birefringence (positive A or negative C plates) in optically isotropic polymer films. We propose a method to make the optical films having the optical biaxiality lying in between that of the positive C and the negative A plates (n_x < n_y < n_z) utilizing the solvent evaporation and the mechanical drawing processes. A theoretical model is proposed to calculate the birefringence induced by the processes. Numerical calculation shows that the biaxial film drawn properly can widen the viewing angle of IPS mode LCDs.