Patent ID: 8363327
Filing Date: 2013-01-29
Classification: G02B

Abstract:
1. A projection lens, comprising: a first lens group composed of a first lens, the first lens having a concave surface and a convex surface, and the convex surface facing a reducing side of the projection lens; a second lens group having positive refractive power and comprising a second lens having positive refractive power and a third lens having negative refractive power, the second lens being located between the first lens and the third lens, the second lens being a biconvex lens, and the third lens having a concave surface facing the reducing side; a third lens group composed of a fourth lens having positive refractive power, the third lens being located between the second lens and the fourth lens, and the fourth lens having a convex surface facing a magnifying side of the projection lens, wherein the first lens group, the second lens group, and the third lens group comprise at least two aspheric lenses; and an aperture stop disposed between the first lens and the second lens.