Patent ID: 8727598

Claim:
A planar light source device, comprising: a light emitting portion including an element array surface on which a plurality of light emitting elements are arrayed; and a light guide plate having both flat surfaces, the light guide plate being stacked on the element array surface and structured to cause light which is emitted by the plurality of light emitting elements to an incident-side surface to propagate inside the light guide plate so as to extract the light from an exit-side surface which is opposite to the incident-side surface, wherein: the element array surface of the light emitting portion has a plurality of recess portions for accommodating the plurality of light emitting elements therein; a non-total reflection region within the exit-side surface of the light guide plate is processed so that at least a part of light emitted from the plurality of light emitting elements toward the exit-side surface is reflected, the non-total reflection region being positioned to oppose each of the plurality of light emitting elements and in the non-total reflection region an incident angle of the light being smaller than a critical angle; the incident-side surface of the light guide plate is processed so as to diffuse and reflect light; wherein the light guide plate comprises white reflective films formed on the exit-side surface and the incident-side surface as the processing for the exit-side surface and the incident-side surface; wherein the white reflective film formed on the incident-side surface changes in surface density depending on a distance from each of the plurality of light emitting elements so that intensity of light emission from the exit-side surface becomes uniform irrespective of the distance; and wherein an area covered by the white reflective film formed on the exit-side surface in the non-total reflection region is less than the non-total reflection region.