PROJECTION OPTICAL SYSTEM, PROJECTOR AND IMAGE READING DEVICE

摘要

A projection optical system which has a short total length but can project a high quality and large image. The projection optical system projects the displayed image on an image displaying surface onto a projection surface, and includes a lens system having a plurality of lenses, and one or more curved mirrors. Light flux of an enlarged image shooting out from the lens system to the projection surface is incident onto a mirror surface of the one of the curved mirrors first of all. A distance OAL and a distance Y satisfy a requirement (1) 20<OAL/Y<30, OAL being the distance between the image surface and the surface of the curved mirror nearest the projection surface and along an optical path shared by the most lenses of the lens system, and on the image surface, and the distance Y being the distance between the optical axis shared by the most lenses and an edge of the image surface which is farthest from the optical axis shared by the most lenses.