# US 12,222,581 B2 · Imaging lens

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- Number: US 12,222,581 B2
- Document ID: US12222581B2
- Status: Granted
- Kind: B2
- Application number: 17/456,518
- Filed: 2021-11-24
- Published: 2022-10-20
- Granted: 2025-02-11
- Earliest claimed: 2020-09-28
- Assignees: Tokyo Visionary Optics Co., Ltd.
- Applicants: Tokyo Visionary Optics Co., Ltd.
- Inventors: Masaki Yamazaki
- Web page: https://patentgrep.com/patent/US12222581B2

## CPC

- G02B 9/60: having five components only
- G02B 13/0045: {having five or more lenses}
- G02B 13/04: Reversed telephoto objectives
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

There is provided an imaging lens with excellent optical characteristics which satisfies demand of a low profile and a low F-number. An imaging lens comprises in order from an object side to an image side, a first lens with positive refractive power, a second lens with negative refractive power, a third lens, a fourth lens with positive refractive power, and a fifth lens with negative refractive power, wherein said first lens has an object-side surface being convex in a paraxial region, said third lens has an image-side surface being convex in a paraxial region, and said fifth lens is formed in a biconcave shape having an object-side surface being concave and an image-side surface being concave in the paraxial region, and predetermined conditional expressions are satisfied.

## Claims

### Claim 1

An imaging lens comprising, in order from an object side to an image side,
a first lens with positive refractive power,
a second lens with negative refractive power,
a third lens,
a fourth lens with positive refractive power, and
a fifth lens with negative refractive power,
wherein said first lens has an object-side surface being convex in a paraxial region, said third lens has an image-side surface being convex in a paraxial region, and said fifth lens is formed in a biconcave shape having an object-side surface being concave and an image-side surface being concave in a paraxial region, and the following conditional expressions (1), (2), (3), (4) and (21a) are satisfied:
−9.00<r3/r7/D2<−4.20 (1)
0.10<r5/r6 (2)
r7/T2<−9.00 (3)
0.50<r10/(D5−T4)<9.50 (4)
0.20<(f4/f)+(f5/f)<0.45 (21a)
where
r3: a paraxial curvature radius of an object-side surface of the second lens,
r7: a paraxial curvature radius of an object-side surface of the fourth lens,
D2: a thickness along the optical axis of the second lens,
r5: a paraxial curvature radius of an object-side surface of the third lens,
r6: a paraxial curvature radius of an image-side surface of the third lens,
T2: a distance along the optical axis from an image-side surface of the second lens to an object-side surface of the third lens,
r10: a paraxial curvature radius of an image-side surface of the fifth lens,
D5: a thickness along the optical axis of the fifth lens,
T4: a distance along the optical axis from an image-side surface of the fourth lens to an object-side surface of the fifth lens,
f4: a focal length of the fourth lens,
f5: a focal length of the fifth lens, and
f: a focal length of the overall optical system of the imaging lens.

### Claim 2 (depends on 1)

The imaging lens according to claim 1, wherein an image-side surface of said first lens is concave in a paraxial region.

### Claim 3 (depends on 1)

The imaging lens according to claim 1, wherein the following conditional expression (5) is satisfied:
17.00<vd3<34.00 (5)
where
vd3: an abbe number at d-ray of the third lens.

### Claim 4 (depends on 1)

The imaging lens according to claim 1, wherein the following conditional expression (6) is satisfied:
1.00<r2/D1<20.50 (6)
where
r2: a paraxial curvature radius of an image-side surface of the first lens, and
D1: a thickness along the optical axis of the first lens.

### Claim 5 (depends on 1)

The imaging lens according to claim 1, wherein the following conditional expression (7) is satisfied:
0.50<r1×r2/f<3.85 (7)
where
r1: a paraxial curvature radius of an object-side surface of the first lens,
r2: a paraxial curvature radius of an image-side surface of the first lens, and
f: a focal length of the overall optical system of the imaging lens.

### Claim 6 (depends on 1)

The imaging lens according to claim 1, wherein the following conditional expression (8) is satisfied:
0.01<r2/r5/r8<0.70 (8)
where
r2: a paraxial curvature radius of an image-side surface of the first lens,
r5: a paraxial curvature radius of an object-side surface of the third lens, and
r8: a paraxial curvature radius of an image-side surface of the fourth lens.

### Claim 7 (depends on 1)

The imaging lens according to claim 1, wherein the following conditional expression (9) is satisfied:
−14.50<r5/r2<−2.50 (9)
where
r5: a paraxial curvature radius of an object-side surface of the third lens, and
r2: a paraxial curvature radius of an image-side surface of the first lens.