# US 11,994,747 B2 · Imaging lens with positive-negative-negative-positive refractive power lenses on object side

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- Number: US 11,994,747 B2
- Document ID: US11994747B2
- Status: Granted
- Kind: B2
- Application number: 17/391,890
- Filed: 2021-08-02
- Published: 2021-11-18
- Granted: 2024-05-28
- Earliest claimed: 2019-01-28
- Assignees: Tokyo Visionary Optics Co., Ltd.
- Applicants: Tokyo Visionary Optics Co., Ltd.
- Inventors: Hitoshi Hirano
- Web page: https://patentgrep.com/patent/US11994747B2

## CPC

- G02B 9/64: having more than six components
- G02B 13/0045: {having five or more lenses}
- G02B 13/002: {having at least one aspherical surface}
- G02B 13/005: {having spherical lenses only}
- G02B 15/14: by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

An imaging lens includes a first lens having positive refractive power; a second lens having negative refractive power; a third lens having negative refractive power; a fourth lens having positive refractive power; a fifth lens; a sixth lens; a seventh lens; an eighth lens; and a ninth lens having negative refractive power, arranged in this order from an object side to an image plane side. The ninth lens is formed in a shape so that a surface thereof on the image plane side has an aspherical shape having an inflection point.

## Claims

### Claim 1

An imaging lens comprising:
a first lens having positive refractive power;
a second lens having negative refractive power;
a third lens having negative refractive power;
a fourth lens having positive refractive power;
a fifth lens;
a sixth lens;
a seventh lens;
an eighth lens; and
a ninth lens having negative refractive power, arranged in this order from an object side to an image plane side,
wherein said ninth lens is formed in a shape so that a surface thereof on the image plane side has an aspherical shape having an inflection point,
the first lens to the ninth lens are arranged with air intervals between adjacent ones of the first lens to the ninth lens, and
all of the nine lenses that compose the imaging lens are made of plastic materials.

### Claim 2 (depends on 1)

The imaging lens according to claim 1, wherein said second lens has a focal length f2 and said third lens has a focal length f3 so that the following conditional expression is satisfied:
0.1<f2/f3<1.2.

### Claim 3 (depends on 1)

The imaging lens according to claim 1, wherein said eighth lens is disposed away from the ninth lens by a distance D89 so that the following conditional expression is satisfied:
0.05<D89/f<0.15,
where f is a focal length of a whole lens system.

### Claim 4 (depends on 1)

The imaging lens according to claim 1, wherein said ninth lens is formed in the shape so that the surface thereof on the image plane side has a paraxial curvature radius R9r so that the following conditional expression is satisfied:
0.2<R9r/f<0.6,
where f is a focal length of a whole lens system.

### Claim 5 (depends on 1)

The imaging lens according to claim 1, wherein said ninth lens has a focal length f9 so that the following conditional expression is satisfied:
−2<f9/f<−0.2,
where f is a focal length of a whole lens system.