Fully passive diffuser stack for a backlight

Abstract

A passive backlight film stack can be composed of several light shaping diffusers, which do not use brightness-enhancing films, light pipes or directional turning films. The passive diffuser stack can be used with direct-view backlights or with the diffuser films, each from 100 to 300 micrometers thick, stacked on top of one another. The passive stack assembly can be formed by two elliptical diffuser films (having different light distribution profiles in horizontal and vertical planes) and one circular diffuser film (with homogeneous distribution in both planes). Each film within the stack has a micro-relief surface diffuser pattern ranging from 5 to 200 microns on a rigid substrate achieved by means of single beam recording in photosensitive media. The light shaping diffusers in the proposed stack have special physical and geometrical characteristics.

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