75‐3: Highly Collimated Backlight for Liquid Crystal Displays

In this work, we present the design of a collimated backlight design that can be used for a liquid crystal display. The design is based on a hexagonal array of white light emitting diodes (LEDs) in combination with two arrays of lenses. Ray tracing simulations show a full width ‐ half maximum (FWHM) collimation angle of 2.8º with a uniformity of 73%. A prototype of this design has been fabricated and its performance has been analyzed. Compared to a standard backlight, the collimated backlight provides a 4.2 times better contrast ratio for a twisted nematic (TN) liquid crystal (LC) panel. In combination with a diffusor in front of the LC panel, the contrast ratio under a wide viewing angle is improved by a factor of 10 and the color shift is reduced by 79%.