IMAGING LENS

Abstract

An imaging lens comprises, in order from an object side: a first lens having a positive refractive power;a second lens having a negative refractive power whose concave surface faces to the object; anda third lens having a positive refractive power and having a meniscus form that has a convex surface, facing to the object, in a portion at and around an optical axis of the imaging lens;wherein the first, second and third lenses have at least one aspheric surface, andwherein the imaging lens satisfies conditional expressions given below:

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a lens sectional view corresponding to an imaging lens according to example 1 of the present invention;

FIG. 2 is a lens sectional view corresponding to an imaging lens according to example 2 of the invention;

FIG. 3 is a lens sectional view corresponding to an imaging lens according to example 3 of the invention;

FIG. 4 is a lens sectional view corresponding to an imaging lens according to example 4 of the invention;

FIG. 5 is a lens sectional view corresponding to an imaging lens according to example 5 of the invention;

FIG. 6 is a lens sectional view corresponding to an imaging lens according to example 6 of the invention;

FIG. 7 is a lens sectional view corresponding to an imaging lens according to example 7 of the invention;

FIGS. 8A and 8B are figures showing the lens data of an imaging lens according to example 1 of the invention, wherein FIG. 8A shows the basic lens data and FIG. 8B shows the lens data concerning an aspheric surface;

FIGS. 9A and 9B are figures showing the lens data of an imaging lens according to example 2 of the invention, wherein FIG. 9A shows the basic lens data and FIG. 9B shows the lens data concerning an aspheric surface;

FIGS. 10A and 10B are figures showing the lens data of an imaging lens according to example 3 of the invention, wherein FIG. 10A shows the basic lens data and FIG. 10B shows the lens data concerning an aspheric surface;

FIGS. 11A and 11B are figures showing the lens data of an imaging lens according to example 4 of the invention, wherein FIG. 11A shows the basic lens data and FIG. 11B shows the lens data concerning an aspheric surface;

FIGS. 12A and 12B are figures showing the lens data of an imaging lens according to example 5 of the invention, wherein FIG. 12A shows the basic lens data and FIG. 12B shows the lens data concerning an aspheric surface;

FIG. 13 is a figure showing the basic lens data of the imaging lens according to example 6 of the invention;

FIG. 14 is a figure showing the lens data concerning aspheric surfaces of the imaging lens according to example 6 of the invention;

FIG. 15 is a figure showing the basic lens data of the imaging lens according to example 7 of the invention;

FIG. 16 is a figure showing the lens data concerning aspheric surfaces of the imaging lens according to example 7 of the invention;

FIG. 17 is a figure showing, collectively on each example, the values related to the conditional expressions;

FIGS. 18A to 18C are aberration diagrams showing the aberrations of the imaging lens according to example 1 of the invention, wherein FIG. 18A shows a spherical aberration, FIG. 18B shows an astigmatism and FIG. 18C shows a distortion;

FIGS. 19A to 19C are aberration diagrams showing the aberrations of the imaging lens according to example 2 of the invention, wherein FIG. 19A shows a spherical aberration, FIG. 19B shows an astigmatism and FIG. 19C shows a distortion;

FIGS. 20A to 20C are aberration diagrams showing the aberrations of the imaging lens according to example 3 of the invention, wherein FIG. 20A shows a spherical aberration, FIG. 20B shows an astigmatism and FIG. 20C shows a distortion;

FIGS. 21A to 21C are aberration diagrams showing the aberrations of the imaging lens according to example 4 of the invention, wherein FIG. 21A shows a spherical aberration, FIG. 21B shows an astigmatism and FIG. 21C shows a distortion;

FIGS. 22A to 22C are aberration diagrams showing the aberrations of the imaging lens according to example 5 of the invention, wherein FIG. 22A shows a spherical aberration, FIG. 22B shows an astigmatism and FIG. 22C shows a distortion;

FIGS. 23A to 23C are aberration diagrams showing the aberrations of the imaging lens according to example 6 of the invention, wherein FIG. 23A shows a spherical aberration, FIG. 23B shows an astigmatism and FIG. 23C shows a distortion; and

FIGS. 24A to 24C are aberration diagrams showing the aberrations of the imaging lens according to example 7 of the invention, wherein FIG. 24A shows a spherical aberration, FIG. 24B shows an astigmatism and FIG. 24C shows a distortion.

Claims

1. An imaging lens comprising, in order from an object side: a first lens having a positive refractive power;a second lens having a negative refractive power whose concave surface faces to the object; anda third lens having a positive refractive power and having a meniscus form that has a convex surface, facing to the object, in a portion at and around an optical axis of the imaging lens;wherein the first, second and third lenses have at least one aspheric surface, andwherein the imaging lens satisfies conditional expressions given below: 0.7<f1/f<1.3  (1)0.2<D2/f<0.6  (2)0.3<|f2/f<0.8  (3)0.5<f3/f<0.8  (4)

2. An imaging lens according to claim 1, wherein a conditional expression given below is further satisfied: 20<ν1−ν2  (5)

3. An imaging lens according to claim 1, wherein the first lens has an object-side surface having a convex form in a portion at and around the optical axis, andthe second lens has a double-concave form in a portion at and around the optical axis.

4. An imaging lens according to claim 1, wherein the first lens has an object-side surface having a convex form in a portion at and around the optical axis, andthe second lens has a meniscus form in a portion at and around the optical axis.

5. An imaging lens according to claim 2, wherein the first lens has an object-side surface having a convex form in a portion at and around the optical axis, andthe second lens has a double-concave form in a portion at and around the optical axis.

6. An imaging lens according to claim 2, wherein the first lens has an object-side surface having a convex form in a portion at and around the optical axis, andthe second lens has a meniscus form in a portion at and around the optical axis.