Patent ID: 9348122
Filing Date: 2016-05-24
CPC Classification: G02B,G03B

Claim Text:
1. A projection lens, comprising: a first lens group, comprising a first spherical lens and a first aspheric lens, wherein an image beam is formed by a light valve passes through the first lens group to form an intermediate image with a first tangential field curvature; and a second lens group, comprising a second spherical lens, a second aspheric lens, a third aspheric lens, a fourth aspheric lens and a twelfth spherical lens; wherein refractive-powers of the third aspheric lens, the fourth aspheric lens, the second spherical lens, the twelfth spherical lens and the second aspheric lens are sequentially negative, positive, positive, negative and negative, wherein the first lens group is located between the light valve and the second lens group, and a lens in the first lens group closest to the second lens group is the first aspheric lens and the intermediate image is formed between the first aspheric lens and the second lens group, wherein the intermediate image with the first tangential field curvature passes through the second lens group to produce a second tangential field curvature, and one of the first tangential field curvature and the second tangential field curvature is a positive tangential field curvature while the other one is a negative tangential field curvature.