Patent ID: 7330318

Claim:
An imaging lens comprising an aperture diaphragm S 1 , a first lens L 1 , a second lens L 2 , and a third lens L 3 , and constituted such that said aperture diaphragm S 1 , said first lens L 1 , said second lens L 2 , and said third lens L 3 are arranged in succession from an object side toward an image side, wherein said first lens L 1 is a lens having a positive refractive power and convex surfaces facing said object side and said image side, said second lens L 2 is a lens having a negative refractive power, a meniscus shape, and a convex surface facing said image side, and said third lens L 3 is a lens having a positive refractive power and convex surfaces facing said object side and said image side, both surfaces of said first lens L 1 are aspherical, both surfaces of said second lens L 2 are aspherical, and both surfaces of said third lens L 3 are aspherical, and said imaging lens satisfies the following conditions: 0.55< |r 2 /r 3 |<0.70 (1-1) 0.08< d 3 /f< 0.12 (1-2) 0.140≦ d 4 /f< 0.270 (1-3) 0.24< d 6 /f< 0.40 (1-4) 0.90< L/ 2 Y< 1.10 (1-5) 0.40< b f /f< 0.52 (1-6) 2.70<F NO <3.60 (1-7) where f is a combined focal length of said imaging lens, r 2 is a radius of curvature (optical axial radius of curvature) of said object-side surface of said first lens L 1 in the vicinity of the optical axis, r 3 is a radius of curvature (optical axial radius of curvature) of said image-side surface of said first lens L 1 in the vicinity of the optical axis, d 3 is an interval on the optical axis between said first lens L 1 and said second lens L 2 , d 4 is a thickness at the center of said second lens L 2 , d 6 is a thickness at the center of said third lens L 3 , L is a distance on the optical axis from said object-side surface of said first lens L 1 to an imaging surface (optical length), 2Y is an image height (effective diagonal length of the image surface), b f is a distance on the optical axis from said image-side surface of said third lens L 3 to said imaging surface, and F NO is an aperture ratio (F number).