Silicon-processed plastic micropyramids for brightness enhancement applications

Abstract

A combination of silicon anisotropic etch and mechanical hot embossing techniques is used to demonstrate the feasibility of manufacturing plastic micropyramids. These micropyramids have the desirable optical characteristics to enhance the brightness of LCD (liquid crystal displays) in battery-powered laptop computers, personal TVs and camcorders. Silicon mold inserts, 4-inch in diameter, are first micromachined and used directly in the micro hot embossing process by applying plastic sheets made of polymethyl methacrylate (PMMA) or polyvinyl chloride (PVC). Micropyramids which have base widths of 30 µm, heights of 21 µm and apex angles of 70° are hot embossed on the surface of plastic sheets. The fabricated plastic films are tested optically and the results show that up to 20% brightness enhancement within the front viewing angles of ±35° have been achieved. An optical model has been established to simulate the brightness enhancement effects and it is concluded that the optimal pyramid angle for the brightness enhancement application is 90°.