FREE-FORM SURFACE LENS, METHOD OF DESIGNING FREE-FORM SURFACE LENS, FREE-FORM SURFACE MIRROR, METHOD OF DESIGNING FREE-FORM SURFACE MIRROR, AND PROJECTION TYPE VIDEO DISPLAY APPARATUS

摘要

A free-form surface lens is made of a transparent resin forming an oblique projection optical system including a free-form surface mirror in a projection type video display apparatus, this lens includes a lens effective region having a surface on which a predetermined free-form surface is formed, and an edge surface formed to surround the lens effective region, the lens effective region and the edge surface in a part of a circumference surrounding the lens effective region where the edge surface is not formed are joined to each other by at least either one of a curved surface and a flat surface set so as not to change a direction of a tilt of the lens effective region in vicinity of the lens effective region, and an end surface including at least either one of the curved surface and the flat surface is set as a tapered surface.