Imaging lens

Patent metadata

Field	Value
Publication number	US-9599799-B2
Application number	US-201615048431-A
Country	US
Kind code	B2
Filing date	Feb 19, 2016
Priority date	May 31, 2013
Publication date	Mar 21, 2017
Grant date	Mar 21, 2017

Abstract

A compact high-resolution imaging lens which provides a wide field of view of 80 degrees or more and corrects various aberrations properly. Designed for a solid-state image sensor, the imaging lens includes constituent lenses arranged in the following order from an object side to an image side: a first positive (refractive power) lens having a convex object-side surface; a second negative lens having a concave image-side surface; a third positive lens as a double-sided aspheric lens having a convex object-side surface; a fourth positive lens having a convex image-side surface; a fifth lens as a double-sided aspheric lens having a concave image-side surface; and a sixth negative lens having a concave image-side surface. The image-side surface of the sixth lens has an aspheric shape with a pole-change point in a position off an optical axis.

First claim

What is claimed is:

1. An imaging lens for a solid-state image sensor, comprising in order from an object side to an image side of the imaging lens:
a first lens having positive refractive power and a convex surface facing the object side;
a second lens having negative refractive power and a concave surface facing the image side;
a third lens that is a double-sided aspheric lens having positive refractive power and a convex surface facing the object side;
a fourth lens having positive refractive power and a convex surface facing the image side;
a fifth lens that is a double-sided aspheric lens having a concave surface facing the image side; and
a sixth lens having negative refractive power and a concave surface facing the image side, an image-side surface of the sixth lens having an aspheric shape with a pole-change point separated from an optical axis of the imaging lens,
wherein the maximum field of view of the imaging lens is 80 degrees or more.

2. The imaging lens according to claim 1 , wherein when f is an overall focal length of the imaging lens, and ih is a maximum image height, a conditional expression (11b) below is satisfied:
0.87≦ih/ f≦ 1.04  (11b).

3. The imaging lens according to claim 1 , wherein when TTL is a distance along the optical axis from an image plane of the imaging lens to an object-side surface of an optical element located nearest an imaged object, and Σd is a distance along the optical axis from an object-side surface of the first lens to the image-side surface of the sixth lens, a conditional expression (9) below is satisfied:
0.65<Σ d /TTL<0.90  (9).

4. The imaging lens according to claim 3 , wherein when f is an overall focal length of the imaging lens, a conditional expression (10) below is satisfied:
TTL/ f< 1.6  (10).

5. The imaging lens according to claim 1 , wherein:
the first lens is a biconvex lens,
the second lens is a meniscus lens,
the fifth lens is a meniscus lens having negative refractive power and each of an object-side surface and an image-side surface of the fifth lens has an aspheric shape with a pole-change point separated from the optical axis, and
the sixth lens is a meniscus lens and an object-side surface of the sixth lens has an aspheric shape with a pole-change point separated from the optical axis.

6. The imaging lens according to claim 1 , wherein when f is an overall focal length of the imaging lens, and f 1 is a focal length of the first lens, a conditional expression (1) below is satisfied:
0.55 <f 1 /f< 1.7  (1).

7. The imaging lens according to claim 6 , wherein when f 2 is a focal length of the second lens, a conditional expression (2) below is satisfied:
−2.3 <f 2 /f<− 0.8  (2).

8. The imaging lens according to claim 7 , wherein when f 3 is a focal length of the third lens, a conditional expression (12) below is satisfied:
1.3 <f 3 /f< 7.0  (12).

9. The imaging lens according to claim 1 , wherein, when νd 1 is an Abbe number of the first lens at d-ray, and νd 2 is an Abbe number of the second lens at d-ray, conditional expressions (3) and (4) below are satisfied:
45<νd1<80  (3)

20<νd2<40  (4).

10. The imaging lens according to claim 1 , wherein, when νd 3 is an Abbe number of the third lens at d-ray, νd 4 is an Abbe number of the fourth lens at d-ray, νd 5 is an Abbe number of the fifth lens at d-ray, and νd 6 is an Abbe number of the sixth lens at d-ray, conditional expressions (5) to (8) below are satisfied:
50<νd3<75  (5)

50<νd4<75  (6)

20<νd5<40  (7)

50<νd6<75  (8).

11. An imaging lens for a solid-state image sensor, comprising, in order from an object side to an image side of the imaging lens:
a first lens having positive refractive power and convex surfaces facing the object side and the image side;
a second lens having negative refractive power, a convex surface facing the object side, and a concave surface facing the image side;
a third lens that is a double-sided aspheric lens having positive refractive power and a convex surface facing the object side;
a fourth lens having positive refractive power and a convex surface facing the image side;
a fifth lens that is a double-sided aspheric lens having a concave surface facing the image side; and
a sixth lens that is a double-sided aspheric lens having a concave surface facing the image side, an image-side surface of the sixth lens having an aspheric shape with a pole-change point separated from an optical axis of the imaging lens,
wherein a composite refractive power of the fifth and sixth lenses is negative.

12. The imaging lens according to claim 11 , wherein when f is an overall focal length of the imaging lens, and ih is a maximum image height, a conditional expression (11) below is satisfied:
0.8<ih/ f< 1.2  (11).

13. The imaging lens according to claim 11 , wherein when TTL is a distance along the optical axis from an image plane of the imaging lens to an object-side surface of an optical element located nearest an imaged object, and Σd is a distance along the optical axis from an object-side surface of the first lens to the image-side surface of the sixth lens, a conditional expression (9) below is satisfied:
0.65 <Σd /TTL<0.90  (9).

14. The imaging lens according to claim 13 , wherein when f is an overall focal length of the imaging lens, a conditional expression (10) below is satisfied:
TTL/ f< 1.6  (10).

15. The imaging lens according to claim 11 , wherein:
the fifth lens is a meniscus lens having negative refractive power and each of an object-side surface and an image-side surface of the fifth lens has an aspheric shape with a pole-change point separated from the optical axis, and
the sixth lens is a meniscus lens and an object-side surface of the sixth lens has an aspheric shape with a pole-change point separated from the optical axis.

16. The imaging lens according to claim 11 , wherein when f is an overall focal length of the imaging lens, and f 1 is a focal length of the first lens, a conditional expression (1) below is satisfied:
0.55 <f 1 /f< 1.7  (1).

17. The imaging lens according to claim 16 , wherein when f 2 is a focal length of the second lens, a conditional expression (2) below is satisfied:
−2.3 <f 2 /f<− 0.8  (2).

18. The imaging lens according to claim 17 , wherein when f 3 is a focal length of the third lens, a conditional expression (12) below is satisfied:
1.3 <f 3 /f< 7.0  (12).

19. The imaging lens according to claim 11 , wherein when νd 1 is an Abbe number of the first lens at d-ray, and νd 2 is an Abbe number of the second lens at d-ray, conditional expressions (3) and (4) below are satisfied:
45<νd1<80  (3)

20<νd2<40  (4).

20. The imaging lens according to claim 11 , wherein when νd 3 is an Abbe number of the third lens at d-ray, νd 4 is an Abbe number of the fourth lens at d-ray, νd 5 is an Abbe number of the fifth lens at d-ray, and νd 6 is an Abbe number of the sixth lens at d-ray, conditional expressions (5) to (8) below are satisfied:
50<νd3<75  (5)

50<νd4<75  (6)

20<νd5<40  (7)

50<νd6<75  (8).

Assignees

• Kantatsu Co Ltd

Inventors

• Sekine Yukio

Classifications

• G02B13/16

  for use in conjunction with image converters or intensifiers {, or for use with projectors, e.g. objectives for projection TV} · CPC title

• G02B9/62

  having six components only · CPC title

• G02B27/0025

  for optical correction, e.g. distorsion, aberration · CPC title

• G02B13/002

  having at least one aspherical surface · CPC title

• G02B3/04

  with continuous faces that are rotationally symmetrical but deviate from a true sphere {, e.g. so called "aspheric" lenses} · CPC title