# US 9,753,258 B2 · Imaging lens composed of seven optical elements

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- Number: US 9,753,258 B2
- Document ID: US9753258B2
- Status: Granted
- Kind: B2
- Application number: 14/952,573
- Filed: 2015-11-25
- Published: 2016-09-29
- Granted: 2017-09-05
- Earliest claimed: 2014-09-30
- Assignees: Kantatsu Co., Ltd.
- Applicants: Kantatsu Co., Ltd.
- Inventors: Masaya Hashimoto
- Web page: https://patentgrep.com/patent/US9753258B2

## CPC

- G02B 13/0045: {having five or more lenses}
- G02B 9/64: having more than six components
- G02B 13/0055: {employing a special optical element}
- G02B 27/0025: {for optical correction, e.g. distorsion, aberration}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A compact low-profile imaging lens which offers a wide field of view and corrects aberrations properly. It includes: a first positive (refractive power) lens having a convex object-side surface as a first optical element; a second negative meniscus lens having a concave image-side surface as a second optical element; a third lens having at least one aspheric surface as a third optical element; a fourth lens having at least one aspheric surface as a fourth optical element; a fifth lens having at least one aspheric surface as a fifth optical element; and a sixth double-sided aspheric lens having a concave image-side surface as a sixth optical element. The aspheric image-side surface of the sixth lens has pole-change points off an optical axis. As a seventh optical element, one double-sided aspheric aberration correction optical element with virtually no refractive power is located between the first lens and an image plane.

## Claims

### Claim 1

An imaging lens which forms an image of an object on a solid-state image sensor, the imaging lens comprising:
a first optical element that is a first lens having positive refractive power and a convex object-side surface;
a second optical element that is a second lens that is a meniscus lens having negative refractive power and a concave image-side surface;
a third optical element that is a third lens having positive or negative refractive power and at least one aspheric surface;
a fourth optical element that is a fourth lens having positive or negative refractive power and at least one aspheric surface;
a fifth optical element that is a fifth lens having positive or negative refractive power and at least one aspheric surface;
a sixth optical element that is a sixth lens that is a double-sided aspheric lens having positive or negative refractive power and a concave image-side surface with an aspheric shape, the image-side surface of the sixth lens having pole-change points separated from an optical axis of the imaging lens; and
a seventh optical element that is one double-sided aspheric aberration correction optical element with virtually no refractive power located between the first lens and an image plane,
wherein the first through sixth optical elements are arranged sequentially from an object side to an image side of the imaging lens, and
conditional expressions (1) to (3) below are satisfied:
0.05<TN/f<0.35 (1)
0.03<dN/f<0.25 (2)
45<νdN<65 (3)
where
f is an overall focal length of the imaging lens,
TN is a distance on the optical axis between lenses where the seventh optical element is located,
dN is a thickness of the seventh optical element on the optical axis, and
νdN is an Abbe number of the seventh optical element at d-ray.

### Claim 2 (depends on 1)

The imaging lens according to claim 1, wherein the seventh optical element is located between the first lens and the second lens.

### Claim 3 (depends on 1)

The imaging lens according to claim 1, wherein the seventh optical element is located between the second lens and the third lens.

### Claim 4 (depends on 1)

The imaging lens according to claim 1, wherein the seventh optical element is located between the third lens and the fourth lens.

### Claim 5 (depends on 1)

The imaging lens according to claim 1, wherein the seventh optical element is located between the fourth lens and the fifth lens.

### Claim 6 (depends on 1)

The imaging lens according to claim 1, wherein the seventh optical element is located between the fifth lens and the sixth lens.

### Claim 7 (depends on 1)

The imaging lens according to claim 1, wherein the seventh optical element is located between the sixth lens and the image plane.

### Claim 8 (depends on 1)

The imaging lens according to claim 1, wherein a conditional expression (4) below is satisfied:
f/EPD<2.40 (4)
where
EPD is an entrance pupil diameter.

### Claim 9 (depends on 1)

The imaging lens according to claim 1,
wherein there are no intervening lenses between the first lens and the second lens, the second lens and the third lens, and the fourth lens and the fifth lens,
composite refractive power of the first lens, the second lens, and the third lens is positive,
composite refractive power of the fourth lens and the fifth lens is positive, and
the refractive power of the sixth lens is negative.

### Claim 10 (depends on 1)

The imaging lens according to claim 1,
wherein there are no intervening lenses between the first lens and the second lens, and the second lens and the third lens, and
a conditional expression (5) below is satisfied:
0.5<f123/f<2.0 (5)
where
f123 is a composite focal length of the first lens, the second lens, and the third lens.

### Claim 11 (depends on 1)

The imaging lens according to claim 1, wherein the fourth lens has positive refractive power, the fifth lens has negative refractive power, and a conditional expression (6) below is satisfied:
2.0<|f5|/f4<10.0 (6)
where
f4 is a focal length of the fourth lens, and
f5 is a focal length of the fifth lens.

### Claim 12 (depends on 1)

The imaging lens according to claim 1, wherein the fourth lens has negative refractive power and the fifth lens has positive refractive power, and a conditional expression (7) below is satisfied:
0.5<|f4|/f5<5.0 (7)
where
f4 is a focal length of the fourth lens, and
f5 is a focal length of the fifth lens.

### Claim 13 (depends on 1)

The imaging lens according to claim 1, wherein a conditional expression (8) below is satisfied:
−1.2<f6/f<−0.5 (8)
where
f6 is a focal length of the sixth lens.

### Claim 14 (depends on 1)

The imaging lens according to claim 1, wherein conditional expressions (9) to (12) below are satisfied:
25<νd1−νd2<40 (9)
45<νd3<65 (10)
20<|νd4−νd5|<40 (11)
45<νd6<65 (12)
where
νd1 is an Abbe number of the first lens at d-ray,
νd2 is an Abbe number of the second lens at d-ray,
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.

### Claim 15 (depends on 1)

The imaging lens according to claim 1, wherein conditional expressions (13) and (14) below are satisfied:
0.5<f1/f<1.5 (13)
−1.6<(r1+r2)/(r1−r2)21 −0.5 (14)
where
f1 is a focal length of the first lens,
r1 is a curvature radius of the object-side surface of the first lens, and
r2 is a curvature radius of an image-side surface of the first lens.

### Claim 16 (depends on 1)

The imaging lens according to claim 1, wherein a conditional expression (15) below is satisfied:
2.0<(r3+r4)/(r3−r4) <10.0 (15)
where
r3 is a curvature radius of an object-side surface of the second lens, and
r4 is a curvature radius of the image-side surface of the second lens.

### Claim 17 (depends on 1)

The imaging lens according to claim 1, wherein a conditional expression (16) below is satisfied:
−0.8<(r11+r12)/(r11−r12) <1.50 (16)
where
r11 is a curvature radius of an object-side surface of the sixth lens, and
r12 is a curvature radius of the image-side surface of the sixth lens.

### Claim 18 (depends on 1)

The imaging lens according to claim 1,
wherein there are no intervening lenses between the first lens and the second lens, the second lens and the third lens, and the fourth lens and the fifth lens,
conditional expressions (17) and (18) below are satisfied:
0.02<f123/f45<1.5 (17)
−22.0<f45/f6<−1.0 (18)
where
f123 is a composite focal length of the first lens, the second lens, and the third lens,
f45 is a composite focal length of the fourth lens and the fifth lens, and
f6 is a focal length of the sixth lens.