Patent ID: 7492533

Claim:
An imaging lens system for forming an optical image of an object on a light receiving surface of a solid-state image sensor, comprising, in order from an object side: an aperture diaphragm; a first lens element having a positive optical power and a convex surface on an image side; a second lens element having a negative optical power and being a meniscus lens whose object side has a concave shape; and a third lens element having a positive optical power and being a meniscus lens whose object side has a convex shape, wherein following conditional expressions are satisfied: 1.9 <|fd/f 2 d|< 3.5 0.9 <|fd/f 3 d|< 2.0 −2.5<( r 201 +r 202 )/( r 201 −r 202 )<−1.4 −1.7<( r 301 +r 302 )/( r 301 −r 302 )<−1.0 wherein, fd is a focal length of an entire lens system to a d-line in mm, f2d is a focal length of the second lens element to the d-line in mm, f3d is a focal length of the third lens element to the d-line in mm, r 201 is a radius of curvature of an object side surface of the second lens element in mm, r 202 is a radius of curvature of an image side surface of the second lens element in mm, r 301 is a radius of curvature of an object side surface of the third lens element in mm, and r 302 is a radius of curvature of an image side surface of the third lens element in mm.