Imaging lens

Abstract

An imaging lens is provided and includes: a positive first lens with a convex surface directed to the object side; a second lens having a negative meniscus shape with a concave surface directed to the image side; a third lens having a positive meniscus shape with a convex surface directed to the image side; a negative fourth lens with both surfaces being an aspheric surface and the image-side surface being concave in the proximity of the optical axis; and a positive or negative fifth lens with both surfaces being an aspheric surface, in order from the object side. The following conditional expressions are satisfied as for Abbe numbers vd1 and vd2 of the first lens and the second lens and Abbe number vd4 of the fourth lens.

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

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

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

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

FIG. 5 is a drawing to show lens data of the imaging lens according to example 1 of the invention; (A) shows lens data and (B) shows lens data concerning aspheric surfaces;

FIG. 6 is a drawing to show lens data of the imaging lens according to example 2 of the invention; (A) shows lens data and (B) shows lens data concerning aspheric surfaces;

FIG. 7 is a drawing to show lens data of the imaging lens according to example 3 of the invention; (A) shows lens data and (B) shows lens data concerning aspheric surfaces;

FIG. 8 is a drawing to show lens data of the imaging lens according to example 4 of the invention; (A) shows lens data and (B) shows lens data concerning aspheric surfaces;

FIG. 9 is a drawing to show the values concerning conditional expressions collectively about the examples;

FIG. 10 is an aberration drawing to show aberrations and distortion of the imaging lens according to example 1 of the invention; (A) shows spherical aberration, (B) shows astigmatism, and (C) shows distortion;

FIG. 11 is an aberration drawing to show aberrations and distortion of the imaging lens according to example 2 of the invention; (A) shows spherical aberration, (B) shows astigmatism, and (C) shows distortion;

FIG. 12 is an aberration drawing to show aberrations and distortion of the imaging lens according to example 3 of the invention; (A) shows spherical aberration, (B) shows astigmatism, and (C) shows distortion;

FIG. 13 is an aberration drawing to show aberrations and distortion of the imaging lens according to example 4 of the invention; (A) shows spherical aberration, (B) shows astigmatism, and (C) shows distortion; and

FIG. 14 is a schematic representation about conditional expressions.

Claims

1. An imaging lens comprising: in order from an object side of the imaging lens, a first lens of a positive lens with a convex surface directed to the object side thereof;a second lens having a negative refractive power and having a meniscus shape with a concave surface directed to an image side thereof;a third lens having a positive refractive power and having a meniscus shape with a convex surface directed to the image side thereof;a fourth lens with both surfaces being an aspheric surface, the fourth lens having a concave surface on the image side in the proximity of an optical axis thereof; anda fifth lens of a positive or negative lens with both surfaces being an aspheric surface,wherein the imaging lens satisfies conditional expressions: vd1>50   (1)vd2<30   (2)vd4<30   (3)

2. The imaging lens according to claim 1 wherein the fourth lens and the fifth lens satisfy conditional expressions: G4D(0.0)<G4D(0.7)<G4D(1.0)   (4)G45D(1.0)<G45D(0.0)   (5)G5MaxH<G4MaxH   (6)

3. The imaging lens according to claim 2, wherein an image-side surface of the fifth lens is concave in the proximity of the optical axis and convex in the periphery of the fifth lens.

4. The imaging lens according to claim 3, further satisfying conditional expressions |f2/f1|>1   (7)1.0<|f3×(1/f4+1/f5)|<1.5   (8)

5. The imaging lens according to claim 3, further comprising an aperture diaphragm closer to the object side than an image-side surface of the first lens.

6. The imaging lens according to claim 3, further comprising an aperture diaphragm between the first lens and the second lens.

7. The imaging lens according to claim 4, further comprising an aperture diaphragm closer to the object side than an image-side surface of the first lens.

8. The imaging lens according to claim 4, further comprising an aperture diaphragm between the first lens and the second lens.

9. The imaging lens according to claim 1, wherein an image-side surface of the fifth lens is concave in the proximity of the optical axis and convex in the periphery of the fifth lens.

10. The imaging lens according to claim 9, further satisfying conditional expressions |f2/f1|>1   (7)1.0<|f3×(1/f4+1/f5)|<1.5   (8)

11. The imaging lens according to claim 9, further comprising an aperture diaphragm closer to the object side than an image-side surface of the first lens.

12. The imaging lens according to claim 9, further comprising an aperture diaphragm between the first lens and the second lens.

13. The imaging lens according to claim 10, further comprising an aperture diaphragm closer to the object side than an image-side surface of the first lens.

14. The imaging lens according to claim 10, further comprising an aperture diaphragm between the first lens and the second lens.

15. The imaging lens according to claim 1, further satisfying conditional expressions |f2/f1|>1   (7)1.0<|f3×(1/f4+1/f5)|<1.5   (8)

16. The imaging lens according to claim 15, further comprising an aperture diaphragm closer to the object side than an image-side surface of the first lens.

17. The imaging lens according to claim 15, further comprising an aperture diaphragm between the first lens and the second lens.

18. The imaging lens according to claim 1, further comprising an aperture diaphragm closer to the object side than an image-side surface of the first lens.

19. The imaging lens according to claim 1, further comprising an aperture diaphragm between the first lens and the second lens.

20. The imaging lens according to claim 2, further satisfying conditional expressions |f2/f1|>1   (7)1.0<|f3×(1/f4+1/f5)|<1.5   (8)

21. The imaging lens according to claim 20, further comprising an aperture diaphragm closer to the object side than an image-side surface of the first lens.

22. The imaging lens according to claim 20, further comprising an aperture diaphragm between the first lens and the second lens.

23. The imaging lens according to claim 2, further comprising an aperture diaphragm closer to the object side than an image-side surface of the first lens.

24. The imaging lens according to claim 2, further comprising an aperture diaphragm between the first lens and the second lens.