Among various liquid crystal display modes, the in-plane switching mode exhibits the widest viewing angle because the liquid crystals are homogeneously-aligned initially and rotate within a plane parallel to the substrates when an in-plane field is applied. However, further improvement is still needed for viewing high-quality dark images from the bisector direction of the crossed polarizers. Several compensation schemes have been proposed to eliminate the off-axis light leakage in a homogeneously-aligned liquid crystal cell. Although a 100:1 iso-contrast contour at an wavelength of 550 nm can cover the entire viewing cone, light leakage at other wavelengths still remains very severe. In this paper we introduce achromatic optical compensation methods using uniaxial films to eliminate the off-axis light leakage at the dark state in homogeneously-aligned liquid crystal cell.Uniaxial films with different dispersion characteristics are used so that they can compensate one another to achieve achromatic optical compensation. The retardation values are optimized through numerical research with the aid of the Poincaré sphere.
Several liquid crystal (LC) modes, such as twisted nematic, vertical alignment (VA), and in-plane switching, have been
in competition with each other in the LC display market. Among them, the VA mode has been widely used because of
the high contrast ratio. Since the LC molecules are aligned perpendicular to the substrate in the initial state, an excellent
dark state can be obtained at normal viewing direction. However, effective phase retardation of LC layer at oblique
viewing direction differs greatly from that at normal viewing direction. Thus, gamma distortion phenomenon occurs at
oblique view direction. To reduce the gamma shift in the VA mode at oblique viewing direction, multi-domain VA
modes were proposed. Although gamma shifts of these modes are smaller than that of the single domain VA mode, the
problems still remain. Recently, several technologies for 8-domain alignment have been proposed to decrease the gamma
shift at off-axis. However, additional driving circuits are required to realize the eight-domain structure. In this paper we
report technologies for the multi-domain VA mode with no additional driving circuits. By using the proposed
technologies, we can obtain the dual threshold voltage in each sub-pixel to realize the multi-domain VA mode with no
decrease of contrast ratio.
In this paper, we propose new pixel structures for high transmittance in the patterned vertical alignment mode.
We formed the protrusion or the slit on the top substrate to reduce the width of disclination lines at the