Imaging lens
AssigneeKantatsu Co., Ltd.
InventorsYoji KUBOTA, Kenichi KUBOTA, Hitoshi HIRANO, Hisao FUKAYA
Life of this patent
Estimating the term…
Abstract
An imaging lens includes a first lens having positive refractive power; a second lens having positive refractive power; a third lens; a fourth lens; a fifth lens; and a sixth lens, arranged in this order from an object side to an image plane side with spaces in between each of the lenses. The first lens is formed in a meniscus shape to have an object side convex surface. The sixth lens is formed in a meniscus shape to have an object side concave surface. The second lens has a specific focal length. The third lens has a specific focal length. The sixth lens has a specific Abbe's number.
Claims20
An imaging lens comprising:
- a first lens having positive refractive power;
- a second lens having positive refractive power;
- a third lens;
- a fourth lens;
- a fifth lens;
- and
- a sixth lens, arranged in this order from an object side to an image plane side with spaces in between each of the lenses,
- wherein said first lens is formed in a shape of a meniscus lens so that a surface thereof on the object side is convex toward the object side near an optical axis thereof,
- said sixth lens is formed in a shape of a meniscus lens so that a surface thereof on the object side is concave toward the object side near an optical axis thereof, and
- said second lens has a focal length f2, said third lens has a focal length f3, and said sixth lens has an Abbe's number νd6 so that the following conditional expressions are satisfied:
- 0.2<|f3/f2|<1.2,
- 35<νd6<75.
An imaging lens comprising:
- a first lens;
- a second lens having positive refractive power;
- a third lens;
- a fourth lens;
- a fifth lens;
- and
- a sixth lens, arranged in this order from an object side to an image plane side with spaces in between each of the lenses,
- wherein said second lens is formed in a shape of a meniscus lens near an optical axis thereof,
- said third lens is formed in a shape so that at least one surface thereof is aspheric,
- said fourth lens is formed in a shape so that at least one surface thereof is aspheric,
- said fifth lens is formed in a shape so that a surface thereof on the object side is convex toward the object side near an optical axis thereof,
- said sixth lens is formed in a shape so that two surfaces thereof are aspheric and the surface thereof on the image plane side is convex toward the image plane side near an optical axis thereof, and
- said second lens has an Abbe's number νd2 so that the following conditional expression is satisfied:
- 35<νd2<75.
An imaging lens comprising:
- a first lens having positive refractive power;
- a second lens;
- a third lens;
- a fourth lens;
- a fifth lens;
- and
- a sixth lens, arranged in this order from an object side to an image plane side with spaces in between each of the lenses,
- wherein said first lens is formed in a shape so that at least one surface thereof is aspheric,
- said third lens is formed in a shape so that at least one surface thereof is aspheric,
- said fourth lens is formed in a shape so that at least one surface thereof is aspheric,
- said fifth lens is formed in a shape so that two surfaces thereof are aspheric and the surface thereof on the object side is convex toward the object side near an optical axis thereof,
- said sixth lens is formed in a shape so that two surfaces thereof are aspheric and the surface thereof on the image plane side is convex toward the image plane side near an optical axis thereof, and
- said second lens has a focal length f2, said third lens has a focal length f3, said second lens has an Abbe's number νd2, and said fifth lens has an Abbe's number νd5 so that the following conditional expressions are satisfied:
- 0.2<|f3/f2|<1.2,
- 35<νd2<75,
- 35<νd5<75.
Dependencies are inferred from the claim text.