Imaging lens

• US 10,598,905 B2
• Filed: 07/30/2019
• Issued: 03/24/2020
• Est. Priority Date: 07/02/2014
• Status: Active Grant

• Current Assignee: Tokyo Visionary Optics Company Limited
• Original Assignee: Kantatsu Company Limited (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Kubota, Yoji, Kubota, Kenichi, Hirano, Hitoshi, Fukaya, Hisao
• Primary Examiner(s): Hasan, Mohammed A
• Application Number:
  US16/525,684
• Publication Number:
  US 20190353875A1
• Time in Patent Office: 238 Days
• Field of Search: 359694-713, 359811-830
• CPC Class Codes: G02B 13/0045 having five or more lenses
• CPC Class Codes: G02B 27/0025 for optical correction, e.g. distorsion, aberration
• CPC Class Codes: G02B 5/005 Diaphragms for cameras G03B9/02
• CPC Class Codes: G02B 9/62 having six components only

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, and a sixth lens. The second lens has a convex surface facing the image plane side near an optical axis thereof. The fifth lens has a concave surface facing the image plane side near an optical axis thereof. The sixth lens has a concave surface facing the object side near an optical axis thereof. The fifth lens has refractive power weaker than those of the fourth lens and the sixth lens. The second lens has a specific Abbe'"'"'s number.

Claims

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,

said second lens group includes a fourth lens, a fifth lens, and a sixth lens,

said second lens has a convex surface facing the image plane side near an optical axis thereof,

said fifth lens has a concave surface facing the image plane side near an optical axis thereof,

said sixth lens has a concave surface facing the object side near an optical axis thereof,

said fifth lens has refractive power weaker than those of the fourth lens and the sixth lens, and

said second lens has an Abbe'"'"'s number vd2 so that the following conditional expression is satisfied;

40<

vd2<

75.

2. The imaging lens according to claim 1, wherein said first lens group has positive refractive power and said second lens group has negative refractive power.

3. The imaging lens according to claim 1, wherein said first lens has a focal length f1 and said second lens has a focal length f2 so that the following conditional expression is satisfied:

0.3<

f1/f2<

0.9.

4. The imaging lens according to claim 1, wherein said first lens has an Abbe'"'"'s number vd1, said second lens has an Abbe'"'"'s number vd2, and said third lens has an Abbe'"'"'s number vd3 so that the following conditional expressions are satisfied:

40<

vd1<

75,

40<

vd2<

75,

15<

vd3<

35.

5. The imaging lens according to claim 1, wherein said first lens group has a focal length F1 so that the following conditional expression is satisfied:

0.8<

F1/f<

1.2,

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

6. The imaging lens according to claim 1, wherein said second lens has a focal length f2 so that the following conditional expression is satisfied:

1.0<

f2/f<

2.0,

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

7. The imaging lens according to claim 1, wherein said first lens has a focal length f1 and said third lens has a focal length f3 so that the following conditional expression is satisfied:

−

1.2<

f1/f3<

−

0.4.

8. The imaging lens according to claim 1, wherein said first lens group has a focal length F1 and said second lens group has a focal length F2 so that the following conditional expression is satisfied:

−

12<

F2/F1<

−

1.5.

9. The imaging lens according to claim 1, wherein said third lens is arranged away from the fourth lens by a distance D34 on an optical axis thereof so that the following conditional expression is satisfied:

0.05<

D34/f<

0.35,

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

10. The imaging lens according to claim 1, wherein said sixth lens has an Abbe'"'"'s number vd6 so that the following conditional expression is satisfied:

40<

vd6<

75.

11. The imaging lens according to claim 1, wherein said fourth lens has a focal length f4 and said fifth lens has a focal length f5 so that the following conditional expression is satisfied:

−

15<

f5/f4<

−

5.

12. The imaging lens according to claim 1, wherein said fifth lens and said sixth lens has a composite focal length f56 so that the following conditional expression is satisfied:

−

3<

f56/f<

−

0.8,

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

13. The imaging lens according to claim 1, wherein said sixth lens has a focal length f6 and said fifth lens and said sixth lens has a composite focal length f56 so that the following conditional expression is satisfied:

0.7<

f6/f56<

1.2.

14. The imaging lens according to claim 1, wherein said sixth lens has a focal length f6 so that the following conditional expression is satisfied:

−

3.5<

f6/f<

0.5,

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