US 8,508,648 B2Granted

Imaging lens

AssigneesOptical Logic Inc., Kantatsu Co., Ltd.

InventorsYoji Kubota, Kenichi Kubota, Hitoshi Hirano, Ichiro Kurihara, Yoshio Ise, Sumio Fukuda

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Abstract

An imaging lens includes an aperture stop ST, a first lens L1 that is shaped to form a meniscus lens that directs a convex surface to the object side near an optical axis and has positive refractive power, a second lens L2 that is shaped to form a meniscus lens that directs a convex surface to the object side near the optical axis and has negative refractive power, a third lens L3 that is shaped to form a meniscus lens that directs a concave surface to the object side near the optical axis and has positive refractive power, and a fourth lens L4 that is shaped to form a meniscus lens that directs a convex surface to the object side near the optical axis, arranged in this order from an object side to an image side. When the first lens L1 has a focal length f1 and the second lens L2 has a focal length f2, the imaging lens is configured such that a relationship 0.3<|f1/f2|<0.7 is satisfied.

Claims18

Dependent claims

An imaging lens comprising:

a first lens having positive refractive power;
a second lens having negative refractive power;
a third lens having positive refractive power;
and
a fourth lens arranged in this order from an object side to an image side,
wherein said first lens is formed so that both a curvature radius of a surface thereof on the object side and a curvature radius of a surface thereof on the image side are positive;
said second lens is formed in a shape so that both a curvature radius of a surface thereof on the object side and a curvature radius of a surface thereof on the image side are positive;
said third lens is formed in a shape so that both a curvature radius of a surface thereof on the object side and a curvature radius of a surface thereof on the image side are negative;
said fourth lens is formed in a shape so that both a curvature radius of a surface thereof on the object side and a curvature radius of a surface thereof on the image side are positive;
when the first lens has a focal length of f1 and the second lens has a focal length f2, the imaging lens is configured to satisfy the following conditional expression:
0.3<|f1/f2|<0.7, and
when the whole lens system has a focal length f and composite focal length of the second lens and the third lens is f23, the imaging lens is configured to satisfy the following conditional expression:
1.5<f23/f<9.0.

10 more elements

An imaging lens comprising:

a first lens having positive refractive power;
a second lens having negative refractive power;
a third lens having positive refractive power;
and
a fourth lens arranged in this order from an object side to an image side,
wherein said first lens is formed so that both a curvature radius of a surface thereof on the object side and a curvature radius of a surface thereof on the image side are positive;
said second lens is formed in a shape so that both a curvature radius of a surface thereof on the object side and a curvature radius of a surface thereof on the image side are positive;
said third lens is formed in a shape so that both a curvature radius of a surface thereof on the object side and a curvature radius of a surface thereof on the image side are negative;
said fourth lens is formed in a shape so that both a curvature radius of a surface thereof on the object side and a curvature radius of a surface thereof on the image side are positive;
when the first lens has a focal length of f1 and the second lens has a focal length f2, the imaging lens is configured to satisfy the following conditional expression:
0.3<|f1/f2|<0.7, and
when a domposite focal length of the first lens and the second lens is f12 and a composite focal length of the second lens and the third lens is f23, the imaging lens is configured to satisfy the following conditional expression:
0.2<f12/f23<1.0.

10 more elements

An imaging lens comprising:

a first lens having positive refractive power;
a second lens having negative refractive power;
a third lens having positive refractive power;
a fourth lens arranged in this order from an object side to an image side;
and
an aperture stop arranged on the object side of the first lens;
wherein said first lens is formed so that both a curvature radius of a surface thereof on the object side and a curvature radius of a surface thereof on the image side are positive;
said second lens is formed in a shape so that both a curvature radius of a surface thereof on the object side and a curvature radius of a surface thereof on the image side are positive;
said third lens is formed in a shape so that both a curvature radius of a surface thereof on the object side and a curvature radius of a surface thereof on the image side are negative;
said fourth lens is formed in a shape so that both a curvature radius of a surface thereof on the object side and a curvature radius of a surface thereof on the image side are positive;
when the first lens has a focal length of f1 and the second lens has a focal length f2, the imaging lens is configured to satisfy the following conditional expression:
0.3<|f1/f2|<0.7, and
said aperture stop has an aperture diameter D and the whole lens system has a focal length f so that the imaging lens is configured to satisfy the following conditional expression:
1.5<f/D<2.8.

11 more elements

Dependencies are inferred from the claim text.