Patent ID: 9013654
Filing Date: 2015-04-21
Classification: G02B

Abstract:
1. A planar illumination device, comprising: a light guide plate having a plurality of light guide sections each having a light-output surface provided in an active light-emitting region and an opposite surface opposite to the light-output surface, the respective light-output surfaces of the light guide sections all facing the same direction; and a group of light sources disposed along an edge face of the light guide plate such that one or a plurality of light sources are provided for each of the light guide sections, wherein, in the light guide plate, one of the following is satisfied: (i) an opposite surface of a first light guide section of the light guide sections is at a height greater than a light-output surface of a second light guide section adjacent to the first light guide section, height being defined with respect to a direction where light is outputted from the light-output surface; (ii) the opposite surface of the first light guide section and the light-output surface of the second light guide section adjacent thereto are at the same height as each other; or (iii) the opposite surface of the first light guide section is in a position at a height greater than an opposite surface of the second light guide section adjacent to the first light guide section, a light-output surface of the first light guide section is in a position at a height greater than the light-output surface of the second light guide section, the opposite surface of the first light guide section is in a position lower than the light-output surface of the second light guide section, and a difference in height between the opposite surface of the first light guide section and the light-output surface of the second light guide section is at most 35% of a difference in height between the light-output surface and the opposite surface of each one of the light guide sections, wherein the light guide plate has a first connective surface connecting the adjacent light-output surfaces, and a second connective surface connecting the adjacent opposite surfaces, and wherein an angle formed between the light-output surface and the first connective surface in the light guide plate, and an angle formed between the opposite surface and the second connective surface in the light guide plate are obtuse angles.