Patent ID: 7246933
Filing Date: 2007-07-24
Classification: G02B,G02F

Abstract:
1. A spread illuminating apparatus comprising: a light conductive plate having a light exit surface provided with a plurality of prisms which define one extension direction, have respective configurations different from one another in cross section taken along a line orthogonal to the extension direction, and which have their respective ridges located on a common virtual plane; at least one point light source disposed at a side surface of the light conductive plate; and a prism sheet having a prism surface provided with a plurality of prisms which define one extension direction, the prism sheet being disposed on the light conductive plate such that the prism surface faces the light exit surface of the light conductive plate, and that the extension direction of the prisms of the prism sheet is oriented substantially orthogonal to the extension direction of the prisms of the light conductive plate; wherein the prisms of the light conductive plate have respective circular arc configurations with a common curvature in cross section taken the line orthogonal to the extension direction thereof; wherein two tangential angles at respective butting ends of adjacent two of the prisms of the light conductive plate are equal to each other; and wherein overall tangential angles at respective ends of the prisms of the light conductive plate are arranged to vary irregularly within a range of 40 to 70 degrees.