Efficient and cost-effective polarized-light backlights for LCDs

摘要

To improve the optical efficiency and to reduce the number of optical components of LCD backlighting systems, two types of polarized-light backlights have been made from micro-structured birefringent polymeric layers. One type uses uniaxially oriented PEN and PET foils that have been structured by diamond-tool machining or by hot-embossing, and subsequently laminated onto a flat PMMA light guide. The second type uses a liquid crystalline polymeric layer laminated onto a micro-structured light guide. S-polarized light is preferentially extracted from the light guides. The efficiency has been measured to be 1.6-1.7 times higher than for a conventional backlight. Costs, thickness and complexity are decreased since no micro-prismatic brightness enhancement foils or reflective polarizer foils are needed.