The polarization efficiency loss in the pre-polarizer has long been a major concern in LCD backlighting. Complying the trend of employing solid state light source, this paper presents a polarization conversion module encapsulated on a white light LED for increasing the degree of polarization at the outlet of the whole packaged LED module, so as to improve the overall energy efficiency of direct-type LED backlighting. The polarization conversion module features a butterfly shape with a wire grid reflective polarizer for separating two orthogonal polarization modes. Due to most of light being incident on the WGP at large angle between 30 and 70 degree, the structure of WGP has been optimized for this range of incident angle, where it is found that dielectric-metal multilayer nanostructure performs superior to the single metal layer structure. With the consideration on the viability of fabrication process, the module with a WGP featuring cross layered dielectric-metal nanostructure has been proposed, fabricated and evaluated. The overall photopic polarization efficiency becomes 72%, and the overall efficiency gain is 1.4X.
|Number of pages||4|
|Journal||Digest of Technical Papers - SID International Symposium|
|State||Published - 1 Jun 2011|