On the purpose of improving the transmittance of LCD panels, the study of polarized illumination has been emphasized as one of the urgent topics to reduce the energy loss at the present absorption-type polarizer of LCD cells. The polarization-selection property of nano-wire-grid structures has been widely studied for a reflective polarizer and applied to increase the transmittance of LCD. For a determined wire-grid polarizer, the transmittance of P polarization (T_p) depends on wavelength and incident angle. The effective incident angle is limited by total internal reflection (TIR) condition of selected polymer materials for wire-grid substrates. This paper presents a polarized backlight unit consisting of an aperture-limited light-guide plate featured by plurality of aluminum-coated trapezoid ridges on the output surface and a hybrid nano wire-grid which has been proposed to improve the transmittance of LCD by polarization recycling and emission angle control. Gain of central brightness was achieved up to 2.1x.
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