Patent ID: 6243211
Filing Date: 2001-06-05
Classification: G02B,H04N

Abstract:
A projection lens system for enlarging and projecting on a screen, an original image displayed on a fluorescent face of a projection tube, said projection lens system comprising, sequentially from the screen side:a first lens group including a meniscus lens having positive refractive power and having a profile of a central area thereof which is convex on the screen side;a second lens group including a lens having positive refractive power and having a profile of a central area thereof which has a convex lens surface on a projection tube side;a third lens group including a lens having positive refractive power;a fourth lens group including a lens having negative refractive power and a concave lens surface on the screen side;a fifth lens group including a lens having positive refractive power and having a profile of a central area thereof which has a convex lens surface on the projection tube side; anda sixth lens group including a lens having negative refractive power and a screen side surface which is concave;wherein said screen side surface of the lens of the sixth lens group is an aspheric surface, and provides refractive power at a marginal area adjacent a periphery of the lens which is weaker than refractive power at an optical axis part of the lens.