Patent ID: 8371739
Filing Date: 2013-02-12
Classification: G02B

Abstract:
1. A backlight unit comprising: a light source; a light guide guiding light from the light source; an optical sheet formed in a substantially rectangular shape and disposed on the light guide; an inner frame having side walls defining an opening therebetween for housing the optical sheet; and a lower frame housing the above; wherein a peripheral portion of the optical sheet has a first projection at each of a pair of longitudinal sides of the optical sheet, a side wall of the inner frame has substantially flat inner surface and defines a projection insertion region partially at the flat inner surface to house the first projection, the peripheral portion of the optical sheet further has a second projection at an other position than that of the first projection, and both the first projection and the second projection are disposed at each of the pair of longitudinal sides of the optical sheet, the second projection is formed smaller than the first projection, one of the first projections or one of the second projections on the one longitudinal side of the optical sheet is disposed to be shifted from the other first projection or the other second projection on the other longitudinal side of the optical sheet, in a longitudinal direction of the optical sheet, and the second projection is disposed in the opening of the inner frame to oppose the flat inner surface of the side wall, the flat inner surface extending from outside of the projection insertion region, while the first projection is engaged in the projection insertion region defined in the side wall.