Patent ID: 6256447
Filing Date: 2001-07-03
Classification: G02B,Y10S

Abstract:
A backlight apparatus comprising:a collimating waveguide having a light input end, a top surface, a bottom surface opposite the top surface, opposing sides, a far end opposite the light input end, and a total internal reflection critical angle;a plurality of first facets in the bottom surface distributed along the collimating waveguide between the light input end and the far end and extending at least part way between the opposing sides;each of the first facets having a first facet bottom surface converging toward the top surface in a direction away from the far end at an angle .gamma. relative to the top surface of less than about 10.degree.;a light scattering and reflective surface disposed adjacent the far end of the collimating waveguide; andwherein the first facet bottom surfaces cause light rays entering the light input end to be totally internally reflected to the far end of the collimating waveguide, wherein the scattering and reflective surface at the far end reflects and scatters light rays incident thereon back toward the light input end, and wherein the first facet bottom surfaces cause light rays reflected from the far end to exit the top surface.