Method of making thin light guide illumination systems using side-emitting leds

Abstract

A method of making a thin waveguide illumination system using side-emitting LED packages is disclosed. The method includes providing an optically transmissive sheet with first and second broad-area surfaces, a light coupling area near the first edge, and a two-dimensional light extraction area on at least one of these surfaces. This light extraction area includes a plurality of light extraction elements with variable density. An LED strip having a heat-conducting printed circuit and a linear array of side-emitting LED packages is positioned parallel to the first edge at or near the first edge, with the major surface of the heat-conducting printed circuit extending generally parallel to the first and second broad-area surfaces. A broad-area reflector is positioned parallel to the second broad-area surface of the sheet. The density of the light extraction elements within the two-dimensional light extraction area increases with distance from the light coupling area.