Patent ID: 7438443
Filing Date: 2008-10-21
Classification: H04N

Abstract:
1. A lighting device comprising: an illumination face that reflects and/or absorbs light and including a length and a width; a light-emitting element including a light emitting diode and a light-ray-releasing face, a maximum length of which light-ray-releasing face is equal to or less than the width of the illumination face; and a light-source unit that has an optical element which changes the direction of light rays released from the light-emitting element to be directed to the illumination face, wherein the optical element has a concave-face reflecting unit including a cross section that is shaped into a quadratic curve or a pseudo quadratic curve (hereinafter, “a quadratic curve”), which is placed at least on one portion thereof, and a luminance distribution on the illumination face has a flat portion that is substantially equal to the width of the illumination face, the concave-face reflecting unit being constituted by a curve that is located on one side when viewed from the vicinity of an apex of the quadratic curve and a symmetric axis of the quadratic curve.