Imaging lens

Patent metadata

Field	Value
Publication number	US-9810884-B2
Application number	US-201615390241-A
Country	US
Kind code	B2
Filing date	Dec 23, 2016
Priority date	May 31, 2013
Publication date	Nov 7, 2017
Grant date	Nov 7, 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 convex surfaces facing the object side and the image side;
a second lens having 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;
a fourth lens that is a double-sided aspheric lens having positive refractive power;
a fifth lens that is a double-sided aspheric lens having negative refractive power and a convex surface facing the object side; and
a sixth lens that is a double-sided aspheric lens, at least one of an object-side surface and an image-side surface of the sixth lens having a pole-change point separated from an optical axis of the imaging lens.

2. The imaging lens according to claim 1 , wherein the second lens has negative refractive power, and the third lens has a convex surface facing the object side.

3. The imaging lens according to claim 1 , wherein the fourth lens has a concave surface facing the object side and a convex surface facing the image side,
the fifth lens has a concave surface facing the image side, at least one of an object-side surface and an image-side surface of the fifth lens having a pole-change point separated from the optical axis, and
the sixth lens has negative refractive power and a concave image-side surface.

4. The imaging lens according to claim 1 , wherein when f is an overall focal length of the imaging lens, and f1 is a focal length of the first lens, a conditional expression (1) below is satisfied:
0.55< f 1/ f< 1.7.  (1)

5. The imaging lens according to claim 2 , wherein when f is an overall focal length of the imaging lens, and f2 is a focal length of the second lens, a conditional expression (2) below is satisfied:
−2.3< f 2/ f<− 0.8.  (2)

6. The imaging lens according to claim 1 , wherein when νd1 is an Abbe number of the first lens at d-ray, and νd2 is an Abbe number of the second lens at d-ray, conditional expressions (3) and (4) below are satisfied:
45<ν d 1<80  (3)

20<ν d 2<40.  (4)

7. The imaging lens according to claim 1 , wherein when νd3 is an Abbe number of the third lens at d-ray, νd4 is an Abbe number of the fourth lens at d-ray, νd5 is an Abbe number of the fifth lens at d-ray, and νd6 is an Abbe number of the sixth lens at d-ray, conditional expressions (5) to (8) below are satisfied:
50<ν d 3<75  (5)

50<ν d 4<75  (6)

20<ν d 5<40  (7)

50<ν d 6<75.  (8)

8. 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)

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

10. 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:
0.8< ih/f< 1.2.  (11)

11. The imaging lens according to claim 1 , wherein when f is an overall focal length of the imaging lens, and f3 is a focal length of the third lens, a conditional expression (12) below is satisfied:
1.3< f 3/ f< 7.0.  (12)

12. 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 a convex surface facing the object side and concave surface facing the image side;
a third lens that is a double-sided aspheric lens;
a fourth lens that is a double-sided aspheric lens having a concave surface facing object 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, at least one of an object-side surface and an image-side surface of the sixth lens having 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.

13. The imaging lens according to claim 12 , wherein the second lens has negative refractive power, and the third lens has positive refractive power and a convex surface facing the object side.

14. The imaging lens according to claim 12 , wherein
the fourth lens has positive refractive power and a convex surface facing the image side,
the fifth lens has a convex surface facing the object side, at least one of an object-side surface and an image-side surface of the fifth lens having a pole-change point separated from the optical axis,
the sixth lens has negative refractive power and a concave image-side surface.

15. The imaging lens according to claim 12 , wherein when f is an overall focal length of the imaging lens, and f1 is a focal length of the first lens, a conditional expression (1) below is satisfied:
0.55< f 1/ f< 1.7.  (1)

16. The imaging lens according to claim 13 , wherein when f is an overall focal length of the imaging lens, and f2 is a focal length of the second lens, a conditional expression (2) below is satisfied:
−2.3< f 2/ f<− 0.8.  (2)

17. The imaging lens according to claim 12 , wherein when νd1 is an Abbe number of the first lens at d-ray, and νd2 is an Abbe number of the second lens at d-ray, conditional expressions (3) and (4) below are satisfied:
45<ν d 1<80  (3)

20<ν d 2<40.  (4)

18. The imaging lens according to claim 12 , wherein when νd3 is an Abbe number of the third lens at d-ray, νd4 is an Abbe number of the fourth lens at d-ray, νd5 is an Abbe number of the fifth lens at d-ray, and νd6 is an Abbe number of the sixth lens at d-ray, conditional expressions (5) to (8) below are satisfied:
50<ν d 3<75  (5)

50<ν d 4<75  (6)

20<ν d 5<40  (7)

50<ν d 6<75  (8).

Assignees

• Kantatsu Co Ltd

Inventors

• Sekine Yukio

Classifications

• G02B13/002

  having at least one aspherical surface · CPC title

• G02B13/16

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

• G02B13/0045 Primary

  having five or more lenses · CPC title

• G02B9/62

  having six components only · 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