Patent ID: 7740392

Claim:
A surface illumination apparatus comprising: a laser light source which emits a substantially parallel laser beam; and a light guide plate comprising: a first main-surface portion; a second main-surface portion opposite said first main-surface portion; a first end-surface portion; and a second end-surface portion located opposite said first end-surface portion, wherein: a laser beam emitted from the laser light source is incident at an inclination angle to the first main-surface portion such that it enters into said light guide plate and the beam is thereafter incident on the second main-surface portion, in said light guide plate, after the direction of an optical path thereof is changed by the first main-surface portion and the beam is reflected within said light guide plate by said first main-surface portion, and the beam is kept polarized and emitted as a substantially parallel beam from the second main-surface portion out of the light guide plate; the first main-surface portion inclines such that the light guide plate becomes thinner from the first end-surface portion toward the second end-surface portion opposite to the first end-surface portion; the first main-surface portion is formed with a plurality of first curved-surface portions from the first end-surface portion toward the second end-surface portion, and the first curved-surface portions reflect the laser beam incident on the first end-surface portions toward of the second main-surface portion; the second main-surface portion is formed with a plurality of second curved-surface portions in positions respectively corresponding to the plurality of first curved-surface portions from the first end-surface portion toward the second end-surface portion, and the second curved-surface portions have a curvature for emitting the laser beam reflected by the first curved-surface portions as a substantially parallel beam from the second main-surface portion; and the laser beam incident on the first end-surface portion of the light guide plate is emitted as a substantially parallel beam from the second main-surface portion of the light guide plate after the direction of the optical path thereof is changed by the first and second curved-surface portions.