Fabrication of Film-Type Light Guide Plates by Using UV Nano-Imprint Lithography to Enhance Optical Properties

Abstract

Light guide plates (LGP) in thin film form were successfully fabricated and characterized on PC and PMMA plastic substrates. PVC stamp was hot embossed by a master mold and various functional resin layers were prepared on the substrates with the stamp by using UV nano imprint lithography (UV-NIL). Optimized pattern density and distribution array were extracted to obtain high brightness and uniformity. In the pattern array, the region with very high density could rather decrease the uniformity due to pattern interference and distortion. We could obtain a relatively improved brightness and a uniformity of 87.3% by using NP-S20 (refractive index n similar to 1.527) functional resin in spite of thin 23-mm-thick polycarbonate (PC, n similar to 1.59) substrate because of its high formability. The LGPs prepared on polymethylmethacrylate (PMMA, n similar to 1.49) substrate exhibited higher brightness compared to those on PC substrate because PMMA has lower refractive index resulting in suppressed total reflection in the substrate.