Patent ID: 8882324
Filing Date: 2014-11-11
Classification: G02B

Abstract:
1. A lighting device comprising: a light source; a light guide provided adjacent to the light source and including a light source light incident surface on which light emitted by the light source enters and a planar light emission surface from which planar light is emitted; and an optical sheet arranged to be opposed to the planar light emission surface of the light guide, including a planar light incident surface on which the planar light enters, and configured to change a traveling direction of the planar light emitted from the light guide because a light emission side of the optical sheet where the light entering from the planar light incident surface is emitted has a shape in which plural columnar prisms extending in parallel to the light source light incident surface are arranged side by side; wherein each of the plural columnar prisms has a plurality of distal surfaces, which are surfaces on a side relatively far from the light source when viewed from a ridgeline of the columnar prism, and a plurality of proximal surfaces, which are surfaces on a side relatively close to the light source when viewed from the ridgeline of the columnar prism; the plurality of distal surfaces and the plurality of proximal surfaces are inclined surfaces for forming an outer shape of the columnar prism; the plurality of distal surfaces incline such that a thickness of the optical sheet is decreased as the distal surfaces are farther away from the ridgeline; the plurality of proximal surfaces incline such that the thickness of the optical sheet is increased as the proximal surfaces are near the ridgeline; at least two of the plurality of distal surfaces have different inclination angles, the inclination angle of a respective distal surface being represented in a range of 0° to 90° and formed with the planar light incident surface by the respective distal surface; and each of the plurality of proximal surfaces is inclined at a larger inclination angle than an inclination angle of each of the plurality of distal surfaces, the inclination angle of a respective proximal surface being represented in a range of 0° to 90° and formed with the planar light incident surface by the respective proximal surface.