Imaging lens

Patent metadata

Field	Value
Publication number	US-10656387-B2
Application number	US-201816186689-A
Country	US
Kind code	B2
Filing date	Nov 12, 2018
Priority date	Aug 31, 2015
Publication date	May 19, 2020
Grant date	May 19, 2020

Abstract

An imaging lens includes a first lens group and a second lens group, arranged in this order from an object side to an image plane side. The first lens group includes a first lens, a second lens, and a third lens. The second lens group includes a fourth lens, a fifth lens having positive refractive power, a sixth lens having two aspheric surfaces, and a seventh lens having two aspheric surfaces. The imaging lens has a total of seven single lenses. The first to seventh lenses are arranged respectively with a space in between. The third lens is formed in a shape so that a surface on the object side is convex. The fourth lens is formed in a shape so that a surface on the object side is concave. The fifth lens is formed in a shape so that a surface on the image plane side is concave.

First claim

What is claimed is:

1. An imaging lens comprising:
a first lens group; and
a second lens group, arranged in this order from an object side to an image plane side,
wherein said first lens group includes a first lens, a second lens, and a third lens, arranged in this order from the object side to the image plane side,
said second lens group includes a fourth lens, a fifth lens having positive refractive power, a sixth lens having two aspheric surfaces, and a seventh lens having two aspheric surfaces, arranged in this order from the object side to the image plane side,
said imaging lens has a total of seven single lenses,
said first lens, said second lens, said third lens, said fourth lens, said fifth lens, said sixth lens, and said seventh lens are arranged respectively with a space in between,
said third lens is formed in a shape so that a surface thereof on the object side is convex near an optical axis thereof,
said fourth lens is formed in a shape so that a surface thereof on the object side is concave near an optical axis thereof,
said fifth lens has at least one aspheric surface, and
said fifth lens is formed in a shape so that a surface thereof on the image plane side is concave near an optical axis thereof.

2. The imaging lens according to claim 1 , wherein said fourth lens is formed in the shape so that the surface thereof on the object side has a curvature radius R4f so that the following conditional expression is satisfied:
−0.6< R 4 f/f<− 0.1,

where f is a focal length of a whole lens system.

3. The imaging lens according to claim 1 , wherein said first lens group is disposed away from the second lens group by a distance Da on an optical axis thereof so that the following conditional expression is satisfied:
0.05< Da/f< 0.3,
where f is a focal length of a whole lens system.

4. The imaging lens according to claim 1 , wherein said fourth lens has a focal length f4 so that the following conditional expression is satisfied:
−3< f 4/ f<− 1,

where f is a focal length of a whole lens system.

5. The imaging lens according to claim 1 , wherein said fifth lens has a focal length f5 so that the following conditional expression is satisfied:
3<| f 5|/ f< 60,
where f is a focal length of a whole lens system.

6. The imaging lens according to claim 1 , wherein said fourth lens has a focal length f4 and said sixth lens has a focal length f6 so that the following conditional expression is satisfied:
−1.3< f 4/ f 6<−0.6.

7. An imaging lens comprising:
a first lens group; and
a second lens group, arranged in this order from an object side to an image plane side,
wherein said first lens group includes a first lens, a second lens, and a third lens, arranged in this order from the object side to the image plane side,
said second lens group includes a fourth lens, a fifth lens having positive refractive power, a sixth lens having two aspheric surfaces, and a seventh lens having two aspheric surfaces, arranged in this order from the object side to the image plane side,
said imaging lens has a total of seven single lenses,
said first lens, said second lens, said third lens, said fourth lens, said fifth lens, said sixth lens, and said seventh lens are arranged respectively with a space in between,
said third lens is formed in a shape so that a surface thereof on the object side is convex near an optical axis thereof,
said fourth lens is formed in a shape so that a surface thereof on the image plane side is convex near an optical axis thereof, and
said fifth lens is formed in a shape so that a surface thereof on the image plane side is concave near an optical axis thereof.

8. The imaging lens according to claim 7 , wherein said fourth lens is formed in the shape so that the surface thereof on the image plane side has a curvature radius R4r so that the following conditional expression is satisfied:
−1.2< R 4 r/f<− 0.3,

where f is a focal length of a whole lens system.

9. The imaging lens according to claim 7 , wherein said first lens group is disposed away from the second lens group by a distance Da on an optical axis thereof so that the following conditional expression is satisfied:
0.05< Da/f< 0.3,
where f is a focal length of a whole lens system.

10. The imaging lens according to claim 7 , wherein said fourth lens has a focal length f4 so that the following conditional expression is satisfied:
−3< f 4/ f<− 1,

where f is a focal length of a whole lens system.

11. The imaging lens according to claim 7 , wherein said fifth lens has a focal length f5 so that the following conditional expression is satisfied:
3<| f 5|/ f< 60,
where f is a focal length of a whole lens system.

12. The imaging lens according to claim 7 , wherein said fourth lens has a focal length f4 and said sixth lens has a focal length f6 so that the following conditional expression is satisfied:
−1.3< f 4/ f 6<−0.6.

13. An imaging lens comprising:
a first lens group; and
a second lens group, arranged in this order from an object side to an image plane side,
wherein said first lens group includes a first lens, a second lens, and a third lens, arranged in this order from the object side to the image plane side,
said second lens group includes a fourth lens, a fifth lens having positive refractive power, a sixth lens having two aspheric surfaces, and a seventh lens having two aspheric surfaces, arranged in this order from the object side to the image plane side,
said imaging lens has a total of seven single lenses,
said first lens, said second lens, said third lens, said fourth lens, said fifth lens, said sixth lens, and said seventh lens are arranged respectively with a space in between,
said third lens is formed in a shape so that a surface thereof on the object side is convex near an optical axis thereof,
said fifth lens is formed in a shape so that a surface thereof on the image plane side is concave near an optical axis thereof, and
said first lens group is disposed away from the second lens group by a distance Da on an optical axis thereof so that the following conditional expression is satisfied:
0.05< Da/f< 0.3,

where f is a focal length of a whole lens system.

14. The imaging lens according to claim 13 , wherein said fourth lens has an Abbe's number νd4 so that the following conditional expression is satisfied:
15<ν d 4<35.

15. The imaging lens according to claim 13 , wherein said seventh lens is formed in a shape so that a surface thereof on the image plane side has a curvature radius R7r so that the following conditional expression is satisfied:
0.2< R 7 r/f< 0.6.

16. The imaging lens according to claim 13 , wherein said first lens group has a focal length F1 and said second lens has a focal length f2 so that the following conditional expression is satisfied:
−8< f 2/ F 1<−1.5.

17. The imaging lens according to claim 13 , wherein said fourth lens has a focal length f4 so that the following conditional expression is satisfied:
−3< f 4/ f<− 1.

18. The imaging lens according to claim 13 , wherein said fifth lens has a focal length f5 so that the following conditional expression is satisfied:
3<| f 5|/ f< 60.

19. The imaging lens according to claim 13 , wherein said fourth lens has a focal length f4 and said sixth lens has a focal length f6 so that the following conditional expression is satisfied:
−1.3< f 4/ f 6<−0.6.

20. The imaging lens according to claim 13 , wherein said second lens group has a focal length F2 and said

Assignees

• Kantatsu Co Ltd

Inventors

• Kubota Yoji
• Kubota Kenichi
• Hirano Hitoshi
• Fukaya Hisao

Classifications

• G02B9/64

  having more than six components · CPC title

• G02B13/0045 Primary

  having five or more lenses · CPC title

• G02B13/0015 Primary

  characterised by the lens design · CPC title