Patent ID: 9664838
Date: 2017-05-30
CPC Classifications: F21S,F21Y,G02B

Claim:
1. An edge-light type illumination device comprising: a light-guide plate; and a primary light source installed on the side of at least one side face of the light-guide plate, in which the light-guide plate has an emission surface, a bottom surface opposed to the emission surface, and a light-receiving end face for receiving light emitted from the primary light source provided on the side of the at least one side face, wherein a normal line of an X-Y plane constituted of an X-axis and a Y-axis orthogonal to the X-axis is represented as a Z-axis, the primary light source is arranged parallel to the X-axis, the light-guide plate is arranged parallel to the X-Y plane, and the light-receiving end face of the light-guide plate is parallel to an X-Z plane, the light-guide plate has a plurality of concave-streak patterns formed at a predetermined pitch on the bottom surface and parallel to an X-axis direction and a plurality of convex-streak patterns formed at a predetermined pitch on the emission surface and parallel to a Y-axis direction, an average intensity of light to be emitted from the emission surface of the light-guide plate is E the total light intensity E wherein an angle θ of the light to be emitted from the emission surface of the light-guide plate relative to the Z-axis direction is 20° and an angle φ of the light to be emitted from the emission surface relative to the X-axis direction is 0°, and the total light intensity E wherein the angle θ of the light to be emitted from the emission surface of the light-guide plate relative to the Z-axis direction is 20° and the angle φ of the light to be emitted from the emission surface relative to the X-axis direction is 90°, the light to be emitted from the emission surface of the light-guide plate also fulfils a condition (2) shown below such that the light emitted from the emission surface of the light guide plate has the following high luminance and anisotropy to luminance distribution conditions: provided that the ΔPi (θ, φ) is a light flux emitted into a minute solid angle of Δω from each compartment in a (θ, φ) direction when the emission surface of the light-guide plate is partioned to a plurality of minute compartments, and Σ is a sum of the plurality of minute compartments of the emission surface of the light-guide plate.