Étendue-squeezing light injector

Abstract

There is currently a desire to produce thinner LED backlights and frontlights so that the devices which use these components can be as thin and lightweight as possible. This is particularly true for smartphones and tablets both of which make extensive use of such components. The push for thinner devices may lead to situations in which the backlights are thinner than the height of the LED emitting area. This paper deals with the coupling of LEDs and thin light guides, describing some possible ways to efficiently inject light from a relatively large LED into a thinner backlight. These solutions use étendue-squeezing optics, and linear edges which allow high-efficiency light injection.