Patent ID: 8553336

Claim:
An image lens for imaging an object on an image plane, in the order from the object side to the image side thereof, comprising: a first lens having positive refraction power and comprising a first surface facing the object side and a second surface facing the image side; and a second lens having negative refraction power and comprising a third surface facing the object side and a fourth surface facing the image side; wherein the image lens satisfies the following formulas: FB/TTL>0.38; (1) R 11/ F 1>2.23; (2) Z/Y> 0.11; (3) Z/T< 0.42; (4) R 23/ F 2< R 12/ F 2< R 24/ F 2; (5) wherein FB is a distance between the fourth surface and the image plane along an optical axis of the image lens, TTL is a total length of the image lens, Z is a distance from a central point of the fourth surface to an outer edge of the fourth surface along the optical axis of the image lens, Y is a distance from the central point of the fourth surface to the outer edge of the fourth surface along a direction perpendicular to the optical axis of the image lens, T is a thickness of the second lens on the optical axis, R 23 is a curvature radius of the third surface, R 24 is a curvature radius of the fourth surface, R 11 is a curvature radius of the first surface; R 12 is a curvature radius of the second surface, and F 2 is a focal length of the second lens.