Abstract: A light emitting module includes at least one LED mounted on a reflective base and surrounded by reflective walls to form a cavity. A partially diffusive layer containing a phosphor is mounted above the LED with a gap therebetween. Some of the light emitted by the phosphor is backscattered toward the LED, base, and walls. The LED absorbs a significant amount of the light, while the reflective base and walls efficiently reflect over 90% of the light back toward the phosphor layer for exiting the module. Various equations are provided that allow the designer to select an optimal gap between the LED and the partially diffusive layer to maximize light extraction efficiency out of the diffusive layer. The optimal gap range for maximizing light extraction efficiency is a product of LED largest linear length, LED surface area, base area, wall area, and reflective coefficients of the various elements.

Abstract: A light emitting module (150) emits light through a light exit window (104) and comprises a base (110), a solid state light emitter (154, 158) and a partially diffusive reflective layer (102). The base (110) has a light reflective surface (112) which faces towards the light exit window (104). The light reflective surface (112) has a base reflection coefficient Rbase which is defined by a ratio between the amount of light that is reflected by the light reflective surface and the amount of light that impinges on the light reflective surface. The solid state light emitter (154, 158) emits light of a first color range (114), comprises a top surface (152, 158) and has a solid state light emitter reflection coefficient R_SSL which is defined by a ratio between the amount of light that is reflected by the solid state emitter (154,156) and the amount of light that impinges on the top surface (152, 158) of the solid state light emitter (1154, 156).