Optical compensation schemes for elimination of off-axis color difference in a light control film based on dichroic dyes

Abstract

We report optical compensation schemes for eliminating off-axis light leakage and color differences when a dichroic dye-based light control film is applied to a display panel. When a vertically aligned dichroic dye (VA-Dye) film without an optical compensation film is applied to the display panel, the light emitted from the display panel can be completely blocked on the upward and downward sides because the absorption axes of the dichroic dye molecules and top polarizer are perpendicular to each other. However, light leakage occurred in the diagonal direction because of the deviation in the angle between the absorption axes. To eliminate off-axis light leakage and off-axis color differences, we present three approaches for optical compensation. First, we optimized the positive biaxial + B plate by controlling its Nz value such that the off-axis color difference could be significantly reduced. Next, we employed optical compensation films using + B/negative C (-C) and positive A (+A)/positive C (+C) configurations. These designed configurations using commercially available films exhibited a significant reduced off-axis color difference as well as the elimination of light leakage in oblique directions when the VA-Dye film was applied to the display panel.