| 摘要 |
PROBLEM TO BE SOLVED: To provide a concealment structure which makes the optical deflection element of a light guide plate invisible and improves front luminance.SOLUTION: The surface light source device 2 of a liquid crystal display device 1 makes light emitted from a light source 11 enter from an end face of a light guide plate 10 and deflects it to an emitting face by an optical deflection element 13. The optical deflection element 13 is arranged by a first pitch Pin a first direction q1 of the optical deflection face 12 and by a second pitch Pin a direction orthogonal to this. The concealment structure 3 has a plurality of first unit lenses 16 formed on the light emission face side 15a and a directional diffusion layer 17 having a function which diffuses more strongly to the second direction q2 than the first direction q1 formed on the light incident face side 15b. In the constitution of the concealment structure having no first unit lenses 16, when the angular distribution of intensity of light in which collimating light is made vertically enter from the light incident face side 15b and emitted from the light emission face side 15a is measured, the half-value angle of the angular distribution of the intensity of light to the second direction q2 is 3 degrees or more and less than 10 degrees. |
