Crucial influences of K33/K11 ratio on viewing angle of display mode using a bend-alignment liquid-crystal cell with a compensator

Abstract

The critical splay-to-bend-alignment transition in a liquid-crystal cell treated by parallel rubbing (π cell) was investigated to improve the optical performance of the display mode using this cell with a compensator. By analyzing the free energy in liquid crystal cells, it was found that nematic media with a smaller K33/K11 ratio can reduce the transition voltage considerably, and therefore, also reduce the required optical anisotropy of the liquid-crystal cell. The significantly improved viewing angle for this mode, achieved by using these newly designed parameters, is also confirmed theoretically and experimentally.

Measurement of the liquid crystal pretilt angle in cells with homogeneous and inhomogeneous liquid crystal director configuration

“…For the cases reviewed in the experimental part of the paper, the K 33 ∕K 11 ratio of the LC materials used is equal to 1.1 and the effect of elastic forces on the optical properties of the cells studied is relatively small. For example, a change in the K 33 ∕K 11 ratio from 0.6 to 2 in cells investigated in [15] results in optical path difference ΔnL from 1.0 to 1.4 μm. Therefore an error that arises owing to the difference of the K 33 ∕K 11 ratio from unity is ∼3%.…”

Modes for Liquid Crystal Devices

“…This is because a satisfactory threedimensional optical compensation can be achieved in the black state. Furthermore, it was shown by analyzing the free energy of bend and splay alignment state that it is possible to stabilize the bend state at a higher voltage than the threshold voltage [62][63][64][65].…”

P‐125: Sequential Color LCD Using No‐Bias Bend Mode

“…Previous studies clearly stated that optically compensated bend (OCB) mode liquid crystal display (LCD) is capable of fast response time [1][2][3][4][5][6]. OCB is a pi-cell which operates from bend to bend states with a critical holding voltage.…”