Patent ID: 7303286

Claim:
A projection display device, comprising: a relay lens for converting a flux that is emitted from a light source into a parallel flux for illuminating an image display element; and a single total internal reflection prism that both guides the flux that is emitted from said relay lens to said image display element and directs the flux that is reflected by said image display element toward a projection lens, said total internal reflection prism shaped as an isosceles triangular prism having a first side surface, a second side surface, and a third side surface, said first side surface forming a total internal reflection surface, said second side surface being arranged facing said image display element, and said third side surface being arranged facing said projection lens; wherein said total internal reflection prism is arranged on a light path between said relay lens and said image display element, and said relay lens is a plano-convex lens having a planar surface and flat portions that are made by cutting at least a part of a circumference of said plano-convex lens, said planar surface is arranged on said total internal reflection surface of said total internal reflection prism opposite to each other at an interval.