Light emitting module, a lamp, a luminaire and a display device

Abstract

A light emitting moduleemits light through a light exit windowand comprises a base, a solid state light emitterand a partially diffusive reflective layer. The basehas a light reflective surfacewhich faces towards the light exit window. The light reflective surfacehas a base reflection coefficient Rbase which i 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 emitteremits light of a first color range, comprises a top surfaceand 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 emitterand the amount of light that impinges on the top surfaceof the solid state light emitter. The light exit windowcomprises at least a part of the partially diffusive reflective layer. A solid state light emitter area ratio ρis defined as the ratio between the area of the top surface of the at least one solid state light emitter and the area of the light reflective surface of the base. A relatively efficient light emitting module is obtained if Rbase>R_SSL+c*(1−R_SSL) and the factor c is 0.2≦c≦1 for 0<ρ<0.1, 0.3≦c≦1 for 0.1≦ρ≦0.25, and 0.4≦c≦1 for ρ>0.25.