Patent ID: 6081387
Filing Date: 2000-06-27
Classification: G02B

Abstract:
A projection lens for projecting an image onto a screen, comprising 5 lenses in 5 groups including: a first-group lens that is a positive lens; a second-group lens that is a positive lens having the largest positive power in the whole lens system; a third-group lens that is a positive lens; a fourth-group lens that is a positive lens; and a fifth-group lens that is negative lens with a concave surface facing a screen side, in order from the screen side, wherein each said lens of the first, third, fourth and fifth groups has at least one aspheric surface, no intervening lens is present between the third group lens and the fourth group lens, and conditions(1) 0.0<f0/f1<0.2,(2) 0.6<f0/f2<0.9,(3) 0.6<.vertline.f5/f34.vertline.<0.8, and(4) 0.0<d2/f0<0.2,whereinf0 is a focal length of the whole projection lens system,f1 is a focal length of the first-group lens,f2 is a focal length of the second-group lens,f5 is a focal length of the fifth-group,f34 is a synthesized focal length of the third group lens and the fourth group lens, andd2 is an air space between the first-group lens and the second-group lens, are satisfied.