Patent ID: 8029160

Claim:
A projection illumination device, comprising: a light source disposed on an axis and transversely crossing the axis at a radiating point thereof, wherein the axis is an optical axis; a lens assembly disposed on the axis, comprising at least two biconvex lenses comprising a front convex side facing the light source, a vertical assist line passing through the radiating point of the light source and utilized to geometrically define the light source and the lens assembly being composed of a first line segment and a second line segment vertically intersected with the first line segment at a corner point, wherein the first line segment is perpendicular to the axis and passes through the radiating point of the light source, and the second line segment is parallel to the axis and tangent to an outermost end of the lens assembly with respect to the axis; and a reflector comprising a continuous reflective surface disposed on the axis and concave to the front convex side of the at least two biconvex lenses of the lens assembly to enclose the lens assembly therein, the corner point of the vertical assist line being located within the reflector, wherein the light source is disposed between the continuous reflective surface of the reflector and the front convex side of the at least two biconvex lenses of the lens assembly, and wherein the light source, the lens assembly and the reflector are arranged such that initial light beams directly radiating to the front convex side of the at least two biconvex lenses without being subject to reflection by the continuous reflective surface of the reflector become refracted light beams traveling parallel to the axis, and initial light beams directly radiating from the radiating point of the light source and reflected by the continuous reflective surface of the reflector become reflected light beams traveling parallel to the axis, wherein the reflected light beams do not impinge upon the lens assembly.