Patent ID: 8054404
Filing Date: 2011-11-08
Classification: G02B

Abstract:
1. A surface light source device comprising: a light source; a light guide plate having (i) two end parts in its length direction, at least one of which serves as an incident surface, and (ii) two end parts in its thickness direction which serve as an exit surface and a back surface, the light guide plate directing light, emitted from the light source, incident on the incident surface, so as to cause the light to exit from a substantially entire area of the exit surface; a first reflector for reflecting and directing the light, emitted from the light source, toward the incident surface; and a dichroic filter column including a plurality of dichroic filters, each reflecting light having a wavelength other than a specific wavelength so as to selectively allow light having the specific wavelength to pass through, the plurality of dichroic filters being arranged on the incident surface so as to have a cyclic permutation in which an identical permutation of dichroic filters each of which selectively allows light having a different wavelength to pass through is repeated in a width direction of the light guide plate, a plurality of light guide paths into which at least one of the two end parts of the light guide plate in the thickness direction is divided, in the width direction of the light guide plate, by a plurality of cutout grooves which are provided to extend in the length direction from portions of the incident surface which portions face respective boundaries between neighboring dichroic filters of the plurality of dichroic filters.