Patent ID: 8885118

Claim:
An illumination device, comprising: a point light source; and a light guide plate having a lateral face serving as a light entrance surface opposed to said point light source, and a main surface serving as a light exit surface, wherein said light entrance surface of said light guide plate is provided with unevenness formed by arraying at predetermined pitches a plurality of first protrusions each projecting from said light entrance surface and extending in a direction perpendicular to said light exit surface, said unevenness has first top surfaces, and second top surfaces, and side surfaces, each of said first and second top surfaces being in the direction perpendicular to said light exit surface, each of said first top surfaces being closer than each of said second top surfaces to a center of said light exit surface, each of said first top surfaces being in between said plurality of first protrusions, each of said side surfaces connecting said first top surface and said second top surface, each of said first and second top surfaces being provided with a plurality of second protrusions, each of said plurality of second protrusions extending in the direction perpendicular to said light exit surface and having a height smaller than each of said plurality of first protrusions, the position of each of tips of said second protrusions in the direction vertical to said light entrance surface is aligned, and each of said side surfaces is flat by means of not being provided with said plurality of second protrusions.