In human vision, glare is caused by a significantly high ratio of luminance between the source of bright light and a nearby area of interest. Glare impairs visibility by reducing contrast from light scattering in the eye, reducing brightness due to pupil restriction, and reducing sensitivity to dark scenes due to a saturated chemical response. As the intensity of glare increases its visual effect can range from discomforting to damaging.
Although polarized sunglasses can selectively reduce most reflected glare, traditional sunglasses have the undesirable effect of reducing the brightness of the entire field of view. Newer sunglasses can alter their transmission with a passively or a manually switchable device. Photochromic lenses are one passive design which reversibly decreases transmission after exposure to ultra-violet (UV) light. One manual design uses the reorientation of liquid crystal molecules to change the absorption of an incorporated dye. However, both designs uniformly darken just like traditional sunglasses. The solution is an actively switchable pixelated design where an individual region of the lens is automatically darkened to shield the source of glare.
This dissertation presents two distinct pixelated glare shielding methods using a liquid crystal display (LCD). The first method uses light absorption performed by attached polarizers which dims the field of view to a constant baseline and pixels between the eye and glare will reduce or eliminate it by darkening further. The mode using this method is the super-twisted nematic (STN). The second glare shielding method uses light scattering performed by a polymer stabilized cholesteric texture (PSCT) liquid crystal configuration which has a transparent field of view and pixels between the eye and glare will reduce or eliminate it by scattering light away from the pupil. This dissertation presents the results of experimental measurements and numerical simulations that characterized both designs for the best performance as defined by driving voltage, brightness and color, contrast ratio, and response time as driven by passive matrix addressing with regard to changes in mixture formulation, cell construction and fabrication procedures.