LIGHTING DEVICE AND IMAGE DISPLAY UNIT AND LIGHT GUIDE PROVIDED WITH IT

摘要

A lighting device comprising a light source (10), and a light guide (20) having an incident surface (20a) for receiving a light emitted from the light source (10) and an output surface (20c) for outputting a light entered via the incident surface (20a). The light guide (20) has a polarization selection layer (22) for selectively outputting via the output surface (20c) a light in a specific polarization direction (first polarization) out of lights incident via the incident surface (20a), and a polarization conversion layer (24) for converting a second polarization different in polarization direction than the first polarization into the first polarization. The polarization selection layer (22) substantially reflects the first polarization toward the output surface (20c) side only.