# US 2014/0153116 A1 · Imaging lens

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- Number: US 2014/0153116 A1
- Document ID: US20140153116A1
- Status: Published application
- Kind: A1
- Application number: 14/090,464
- Filed: 2013-11-26
- Published: 2014-06-05
- Earliest claimed: 2012-11-30
- Assignees: Kantatsu Co., Ltd.; Optical Logic Inc.
- Applicants: Kantatsu Co., Ltd.; Optical Logic Inc.
- Inventors: Yoji KUBOTA; Kenichi KUBOTA; Hitoshi HIRANO; Tomohiro YONEZAWA
- Web page: https://patentgrep.com/patent/US20140153116A1

## CPC

- G02B 13/004: {having four lenses}
- G02B 9/34: having four components only
- G02B 27/0025: {for optical correction, e.g. distorsion, aberration}
- G02B 1/11: Anti-reflection coatings
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

An imaging lens includes a first lens having negative refractive power; a second lens having positive refractive power; a third lens having positive refractive power; a stop; and a fourth lens having positive refractive power arranged in the order from an object side to an image plane side. The first lens has an image plane-side surface having a positive curvature radius. The second lens has an image plane-side surface having negative curvature radius. The third lens has an image plane-side surface having a negative curvature radius. The fourth lens has an object-side surface having a positive curvature radius and an image plane-side surface having a negative curvature radius. The first lens has a specific focal length and a specific Abbe's number to satisfy specific conditional expressions.

## Claims

### Claim 1

An imaging lens comprising:
a first lens having negative refractive power;
a second lens having positive refractive power;
a third lens having positive refractive power;
a stop; and
a fourth lens having positive refractive power, arranged in this order from an object side to an image plane side,
wherein said first lens is formed in a shape so that a surface thereof on the image plane side have a positive curvature radius,
said second lens is formed in a shape so that a surface thereof on the image plane side have a negative curvature radius,
said third lens is formed in a shape so that a surface thereof on the image plane side has a negative curvature radius,
said fourth lens is formed in a shape so that a surface thereof on the object side has a positive curvature radius and a surface thereof on the image plane side has a negative curvature radius, and
said first lens has a focal length f1 and an Abbe's number νd1 so that the following conditional expressions are satisfied:
−75<f1/f<−5.0
45<νd1<70
where f is a focal length of a whole lens system.

### Claim 2 (depends on 1)

The imaging lens according to claim 1, wherein said first lens is formed in an aspheric shape so as the first lens has refractive power increasing from an optical axis thereof toward a periphery thereof.

### Claim 3 (depends on 1)

The imaging lens according to claim 1, wherein each of said first lens, said second lens, and said third lens has a focal length three times greater than that of the fourth lens.

### Claim 4 (depends on 1)

The imaging lens according to claim 1, wherein said fourth lens has a focal length f4 so that the following conditional expression is satisfied:
1.0<f4/f<2.5
where f is the focal length of the whole lens system.

### Claim 5 (depends on 1)

The imaging lens according to claim 1, wherein said second lens and said third lens have a composite focal length f23, and said fourth lens has a focal length f4 so that the following conditional expression is satisfied:
0.2<f4/f23<1.0.

### Claim 6 (depends on 1)

The imaging lens according to claim 1, wherein said first lens, said second lens, and said third lens have a composite focal length f123 so that the following conditional expression is satisfied:
2.0<f123/f<5.0
where f is the focal length of the whole lens system.

### Claim 7 (depends on 1)

The imaging lens according to claim 1, wherein said first lens is situated away from the second lens by a distance dA on an optical axis thereof so that the following conditional expression is satisfied:
0.3<dA/f<1.0
where f is the focal length of the whole lens system.

### Claim 8 (depends on 1)

The imaging lens according to claim 1, wherein said third lens has an Abbe's number νd3 and said fourth lens has Abbe's number νd4 so that the following conditional expressions are satisfied:
20<νd3<40
45<νd4<70