Optical system for ultrathin projection TV

摘要

A rear projection optical system that performs enlarged projection from the primary image plane on the reduction side to the second image plane on the enlargement side without forming an intermediate real image has: a refractive lens group including an aperture; a bending mirror that rotates the optical axis for the optical system after said bending mirror by approximately 90 degrees; for performing enlargement projection from a primary image surface located on the reduction side to a secondary image surface located on the enlargement side has, from the secondary image surface side, at least two reflective surfaces. Of the first and the second reflective surface counted from the secondary image surface side, at least one has a negative optical power. At least one Fresnel reflective surface having a positive or negative optical power is disposed within the entire projection optical system.