Viewing angle control of a patterned vertical alignment (PVA) liquid crystal display using only one panel is investigated. In conventional PVA modes, a vertically aligned liquid crystal (LC) director tilts down in four directions making 45 • with respect to crossed polarizers to exhibit a wide viewing angle. In the viewing angle control device, one pixel was divided into two sub-pixels such that the LC director in the main pixel is controlled to be tilted down in multiple directions making an angle with the polarizer, playing the role of main display with the wide viewing angle, while the LC director in the sub-pixel is controlled to be tilted down to the polarizer axis, playing the role of sub-pixel to the viewing angle control for the narrow viewing angle. Using sub-pixel control, light leakage or any type of information such as characters and image can be generated in oblique viewing directions without distorting the image quality in the normal direction, which will prevent others from peeping at the displayed image by overlapping the displayed image with the made image.

In this paper, we propose an optical configuration for a reflective liquid crystal (LC) cell with a single polarizer that can show an excellent contrast ratio by effectively eliminating phase dispersion. The proposed configuration consists of a half-wave retarder, two A-plates, a quarter-wave LC cell and a reflector; the configuration was designed on a Poincaré sphere with the trigonometric method. From the calculation, we confirm that this configuration can show a high contrast ratio as compared with the conventional configuration due to the excellent dark state.

We propose an optical structure for a vertical alignment (VA) liquid crystal (LC) cell with a wide viewing angle. The proposed LC cell consists of an A-plate and two C-plates for optical compensation. Optical compensation and optimization to eliminate off-axis light leakage in the entire visible wavelength range are performed on a Poincaré sphere using the Stokes vector and the Muller matrix method. After optimizing the wavelength dispersion of the retardation films that are used, we prove that the proposed VA LC cell can improve the viewing angle and contrast ratio by calculating optical characteristics, particularly in diagonal directions.

No abstract

No abstract