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 • .

Fabrication of Viewing Angle Direction Brightness-Enhancement Optical Films using Surface Textured Silicon Wafers

“…3 and 5. Compared with the previous work [1], brightness enhancement (15~20%) is lower, maybe due to dirt or imperfect index matching between film and BLU.…”

“…There are many methods that employ conventional photo-lithography and semi-conductor fabrication processes. These techniques require high cost and many more process steps including two step-etch masking and dry etching and replications [1]. In contrast, our proposed method uses only simple wet etching along with sonication, moreover master patterns can be fabricated as large as the available silicon wafer (up to 8" in this work).…”

“…We have already checked alternative fabrication methods for pattern master using photo-lithography and dielectric etch mask (SiO 2 , SiN x ) to form highly ordered lattice-like patterns with uniform size [1,2,15]. When we compare the uniformity and brightness of films between randomlypositioned and periodic-positioned patterns, data showed no considerable differences in brightness enhancement.…”

“…Therefore optical films are generally employed when LED lighting devices are assembled and packaged. Their role is to redistribute the light rays coming out from the point LED sources and uniformly radiate onto the forward direction without sacrificing illuminance [1][2][3][4].…”

Integration of stamper fabrication and design optimization of LCD Light guides using silicon-based microfeatures

“…Design optimization using simulation tools is futile when feature geometry and distribution cannot be realized precisely. Silicon etching and the MEMS technique can be applied to fabricate precision v-slots and pyramid structures for the forming of LGPs and bright enhancement films (BEFs) (Chien and Chen 2006, Lin et al 2000, Taniguchi et al 2004). However, the sharp tips of micro features often result in forming and wear problems.…”