Patent ID: 7419292
Filing Date: 2008-09-02
Classification: G02B

Abstract:
1. An illuminating device comprising: a light source; an optical waveguide that has a wedge shape in sectional view and that includes a light incident surface, an emission surface, and a reflective surface, the emission surface and the reflective surface being opposite from each other, the emission surface emitting light from the light source and the reflective surface having an inclination angle that is smaller than 5° with respect to the emission surface; and a prism sheet that is provided on the emission surface side of the optical waveguide, wherein the following relationship is established between a refractive index x of the prism sheet and an apex angle y of prisms in the prism sheet: wherein x is 1.7 to 1.8 and y is 42.93° to 53.72°.