The light source device of a display device according to the present invention has an optical waveguide, a cone sheet, and a light source disposed along the side surface of the optical waveguide. The light-emitting surface of the optical waveguide is flat, and a tilted surface that is tilted towards the light source with respect to the light-emitting surface is formed on the light-diffusing surface. The cone sheet has a flat plate and a plurality of circular cones arranged two-dimensionally on the light-incident surface of the flat plate. The central axes of the circular cones are parallel to each other. The invention provides a light source device that can be made thin and is capable of increasing the directivity of emitted light in two dimensions.

 
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> Back light module having concave-down luminance distribution

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