Imaging lens

Abstract

An imaging lens is provided and includes: in order from an object side of the imaging lens, a first lens having a convex surface directed to the object side on an optical axis and having a positive power; an aperture diaphragm placed between a top position of an object-side surface of the first lens and a position of an image-side surface of the first lens on the optical axis; a second lens having a meniscus shape with a concave surface directed to the object side on the optical axis; and a third lens having a meniscus shape with a convex surface directed to the object side on the optical axis. Further, the imaging lens satisfies specific conditional expressions.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the invention will appear more fully upon consideration of the exemplary embodiment of the invention, which are schematically set forth in the drawings, in which:

FIG. 1 shows a first example of an imaging lens as one exemplary embodiment of the invention and is a sectional view corresponding to example 1;

FIG. 2 shows a second example of an imaging lens as one exemplary embodiment of the invention and is a sectional view corresponding to example 2;

FIG. 3 shows a third example of an imaging lens as the embodiment of the invention and is a sectional view corresponding to example 3;

FIG. 4 shows a fourth example of an imaging lens as the embodiment of the invention and is a sectional view corresponding to example 4;

FIG. 5 shows a fifth example of an imaging lens as the embodiment of the invention and is a sectional view corresponding to example 5;

FIG. 6 shows a sixth example of an imaging lens as the embodiment of the invention and is a sectional view corresponding to example 6;

FIG. 7 shows a seventh example of an imaging lens as the embodiment of the invention and is a sectional view corresponding to example 7;

FIG. 8 shows lens data in the imaging lens in example 1;

FIG. 9 shows data concerning aspheric surfaces in the imaging lens in example 1;

FIG. 10 shows lens data in the imaging lens in example 2;

FIG. 11 shows data concerning aspheric surfaces in the imaging lens in example 2;

FIG. 12 shows lens data in the imaging lens in example 3;

FIG. 13 shows data concerning aspheric surfaces in the imaging lens in example 3;

FIG. 14 shows lens data in the imaging lens in example 4;

FIG. 15 shows data concerning aspheric surfaces in the imaging lens in example 4;

FIG. 16 shows lens data in the imaging lens in example 5;

FIG. 17 shows data concerning aspheric surfaces in the imaging lens in example 5;

FIG. 18 shows lens data in the imaging lens in example 6;

FIG. 19 shows data concerning aspheric surfaces in the imaging lens in example 6;

FIG. 20 shows lens data in the imaging lens in example 7;

FIG. 21 shows data concerning aspheric surfaces in the imaging lens in example 7;

FIG. 22 shows the numeric values corresponding to conditional expressions (1) to (7) in the imaging lenses in examples 1 to 7;

FIG. 23 shows spherical aberration, astigmatism, and distortion in the imaging lens of example 1;

FIG. 24 shows spherical aberration, astigmatism, and distortion in the imaging lens of example 2;

FIG. 25 shows spherical aberration, astigmatism, and distortion in the imaging lens of example 3;

FIG. 26 shows spherical aberration, astigmatism, and distortion in the imaging lens of example 4;

FIG. 27 shows spherical aberration, astigmatism, and distortion in the imaging lens of example 5;

FIG. 28 shows spherical aberration, astigmatism, and distortion in the imaging lens of example 6; and

FIG. 29 shows spherical aberration, astigmatism, and distortion in the imaging lens of example 7.

Claims

1. An imaging lens comprising: in order from an object side of the imaging lens, a first lens having a convex surface directed to the object side on an optical axis and having a positive power;an aperture diaphragm placed between a top position of an object-side surface of the first lens and a position of an image-side surface of the first lens on the optical axis;a second lens having a meniscus shape with a concave surface directed to the object side on the optical axis; anda third lens having a meniscus shape with a convex surface directed to the object side on the optical axis,whereinthe imaging lens satisfies all conditional expressions (1) to (3): 0.5<f1/f<2.0  (1)0.5<(|R2|−R1)/(R1+|R2|)≦1.0  (2)0.5<|f2/f|<3.0  (3)

2. The imaging lens according to claim 1, further satisfying conditional expression (4): 0.9<f3/f<3.0  (4)

3. The imaging lens according to claim 2, wherein the second lens has a negative power, and the imaging lens satisfies conditional expression (7): v1−v2>20  (7)

4. The imaging lens according to claim 3, further satisfying conditional expression (5): bf/TL>0.2  (5)

5. The imaging lens according to claim 4, further satisfying conditional expression (6): TL/(2×Ih)<1.2  (6)

6. The imaging lens according to claim 5, wherein the aperture diaphragm is placed between the top position of the object-side surface of the first lens and an edge position of the object-side surface of the first lens on the optical axis.

7. The imaging lens according to claim 3, wherein the aperture diaphragm is placed between the top position of the object-side surface of the first lens and an edge position of the object-side surface of the first lens on the optical axis.

8. The imaging lens according to claim 2, further satisfying conditional expression (5): bf/TL>0.2  (5)

9. The imaging lens according to claim 8, further satisfying conditional expression (6): TL/(2×Ih)<1.2  (6)

10. The imaging lens according to claim 9, wherein the aperture diaphragm is placed between the top position of the object-side surface of the first lens and an edge position of the object-side surface of the first lens on the optical axis.

11. The imaging lens according to claim 2, wherein the aperture diaphragm is placed between the top position of the object-side surface of the first lens and an edge position of the object-side surface of the first lens on the optical axis.

12. The imaging lens according to claim 1, wherein the second lens has a negative power, and the imaging lens satisfies conditional expression (7): v1−v2>20  (7)

13. The imaging lens according to claim 12, further satisfying conditional expression (5): bf/TL>0.2  (5)

14. The imaging lens according to claim 13, further satisfying conditional expression (6): TL/(2×Ih)<1.2  (6)

15. The imaging lens according to claim 14, wherein the aperture diaphragm is placed between the top position of the object-side surface of the first lens and an edge position of the object-side surface of the first lens on the optical axis.

16. The imaging lens according to claim 12, wherein the aperture diaphragm is placed between the top position of the object-side surface of the first lens and an edge position of the object-side surface of the first lens on the optical axis.

17. The imaging lens according to claim 1, further satisfying conditional expression (5): bf/TL>0.2  (5)

18. The imaging lens according to claim 17, further satisfying conditional expression (6): TL/(2×Ih)<1.2  (6)

19. The imaging lens according to claim 18, wherein the aperture diaphragm is placed between the top position of the object-side surface of the first lens and an edge position of the object-side surface of the first lens on the optical axis.

20. The imaging lens according to claim 1, wherein the aperture diaphragm is placed between the top position of the object-side surface of the first lens and an edge position of the object-side surface of the first lens on the optical axis.