Patent ID: 8210732

Claim:
A light guide plate assembly, comprising: a light guide plate which includes a light exit plane for emitting a planar light and a light entrance end disposed in one end of the light exit plane and substantially orthogonal to the light exit plane, is formed into a shape having a thickness in a direction orthogonal to the light exit plane, the thickness being gradually larger as being farther from the light entrance end, and contains scattering particles dispersed therein; and a prism sheet which includes a plurality of prisms arrayed in parallel with each other, and is arranged so that vertex angles of the plurality of prisms face the light exit plane of the light guide plate, wherein: the scattering particles scatter light entering from the light entrance end and propagating in the light guide plate, which satisfy Expressions (1) and (2) below; when lengths of two straight lines sandwiching each of the vertex angles of the plurality of prisms of the prism sheet are equal to each other, an angle formed between the two straight lines of the equal lengths satisfies Expression (3) below; and when the lengths of the two straight lines sandwiching the each of the vertex angles of the plurality of prisms are different from each other, an angle formed between the straight lines of the different lengths satisfies Expression (4) below, 1.1≦ΦN p L G K C ≦8.2 (1) 0.005≦K c ≦0.1 (2) 55°≦θ≦80° (3) 0°≦θ 1 ≦15° and 30°≦θ 2 ≦45° (4) in Expressions (1) and (2), Φ represents a scattering cross section [m 2 ] of the scattering particles, N p represents a density [pieces/m 2 ] of the scattering particles, L G [m] represents a length extending from the light entrance end to a thickest part of the light guide plate in an entrance direction, and Kc represents a compensation coefficient, in Expression (3), θ represents the angle formed between the two straight lines of the equal lengths, and in Expression (4), θ 1 represents an angle formed between a perpendicular from a vertex of each of the vertex angles of the plurality of prisms with respect to a bottom of each of the plurality of prisms and one of the straight lines of the different lengths, and θ 2 represents an angle formed between the perpendicular and another of the straight lines of the different lengths.