# US 2013/0155528 A1 · Optical lens system for image taking

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- Number: US 2013/0155528 A1
- Document ID: US20130155528A1
- Status: Published application
- Kind: A1
- Application number: 13/445,260
- Filed: 2012-04-12
- Published: 2013-06-20
- Earliest claimed: 2011-12-19
- Assignees: Largan Precision Co., Ltd.
- Inventors: Tsung-Han Tsai; Ming-Ta Chou
- Web page: https://patentgrep.com/patent/US20130155528A1

## CPC

- G02B 13/0035: {having three lenses}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

An optical lens system for image taking includes, in order from an object side to an image side, a first lens element with positive refractive power having a convex object-side surface, a second lens element with negative refractive power having a concave object-side surface and a concave image-side surface with the at least one surface being aspheric, and a third lens element with positive refractive power having a convex object-side surface and a concave image-side surface with the at least one surface being aspheric. The image-side surface of the third lens element includes at least one inflection point. By adjusting spacing between any two lens elements, the optical lens system for image taking has a desirable space allocation and can effectively correct the Petzval Sum in order to obtain superior imaging quality.

## Claims

### Claim 1

An optical lens system for image taking comprising, in order from an object side to an image side:
a first lens element with positive refractive power comprising a convex object-side surface;
a second lens element with negative refractive power comprising a concave object-side surface and a concave image-side surface, and at least one of the object-side surface and the image-side surface being aspheric; and
a third lens element with negative refractive power comprising a convex object-side surface and a concave image-side surface, at least one of the object-side surface and the image-side surface being aspheric, and the image-side surface comprising at least one inflection point;
the optical lens system for image taking satisfying the following condition:
0.6<T12/T23<2.55;
wherein T12 is the axial distance between the first lens element and the second lens element, and T23 is the axial distance between the second lens element and the third lens element.

### Claim 2 (depends on 1)

The optical lens system for image taking according to claim 1, wherein the optical lens system for image taking satisfies the following condition:
0.85<f/f1<1.65;
wherein f is the focal length of the optical lens system for image taking, and f1 is the focal length of the first lens element.

### Claim 3 (depends on 2)

The optical lens system for image taking according to claim 2, wherein the optical lens system for image taking satisfies the following condition:
−0.8<R3/R4<0;
wherein R3 is the curvature radius of the object-side surface of the second lens element, and R4 is the curvature radius of the image-side surface of the second lens element.

### Claim 4 (depends on 3)

The optical lens system for image taking according to claim 3, wherein the first lens element comprises an image-side surface and the optical lens system for image taking satisfies the following condition:
−2.0<(R1+R2)/(R1−R2)<−0.5;
wherein R1 is the curvature radius of the object-side surface of the first lens element, and R2 is the curvature radius of the image-side surface of the first lens element.

### Claim 5 (depends on 3)

The optical lens system for image taking according to claim 3, wherein the optical lens system for image taking satisfies the following condition:
0.7<T12/T23<1.8;
wherein T12 is the axial distance between the first lens element and the second lens element, and T23 is the axial distance between the second lens element and the third lens element.

### Claim 6 (depends on 3)

The optical lens system for image taking according to claim 3, wherein the optical lens system for image taking satisfies the following condition:
0.2<R6/f<0.8;
wherein R6 is the curvature radius of the image-side surface of the third lens element, and f is the focal length of the optical lens system for image taking.

### Claim 7 (depends on 3)

The optical lens system for image taking according to claim 3, wherein the optical lens system for image taking satisfies the following condition:
−1.05<f/f2<−0.1;
wherein, f is the focal length of the optical lens system for image taking, and f2 is the focal length of the second lens element.

### Claim 8 (depends on 3)

The optical lens system for image taking according to claim 3, wherein the first lens element comprises an image-side surface, the object-side surfaces and the image-side surfaces of the first, second, and third lens elements are aspheric, and the first, second, and third lens elements are made of plastic.

### Claim 9 (depends on 2)

The optical lens system for image taking according to claim 2, wherein the optical lens system for image taking satisfies the following condition:
29<V1−V2<50;
wherein V1 is the Abbe number of the first lens element, and V2 is the Abbe number of the second lens element.

### Claim 10 (depends on 2)

The optical lens system for image taking according to claim 2, wherein the optical lens system for image taking satisfies the following condition:
1.00<f/f1<1.47;
wherein f is the focal length of the optical lens system for image taking, and f1 is the focal length of the first lens element.

### Claim 11 (depends on 2)

The optical lens system for image taking according to claim 2, wherein the optical lens system for image taking further comprises an image plane and the optical lens system for image taking satisfies the following condition:
TTL/ImgH<2.0;
wherein TTL is the axial distance between the object-side surface of the first lens element and the image plane, and ImgH is a maximal image height of the optical lens system for image taking.

### Claim 12

An optical lens system for image taking comprising, in order from an object side to an image side:
a first lens element with positive refractive power comprising a convex object-side surface;
a second lens element with negative refractive power comprising a concave object-side surface and a concave image-side surface, and both the object-side surface and the image-side surface being aspheric; and
a third lens element comprising a convex object-side surface and a concave image-side surface, and both the object-side surface and the image-side surface being aspheric;
the optical lens system for image taking satisfying the following condition:
0.6<T12/T23<2.55;
−0.8<R3/R4<0;
−1.05<f/f2<−0.1; and
0<|f/f3|<0.55;
wherein T12 is the axial distance between the first lens element and the second lens element, T23 is the axial distance between the second lens element and the third lens element, R3 is the curvature radius of the object-side surface of the second lens element, R4 is the curvature radius of the image-side surface of the second lens element, f is the focal length of the optical lens system for image taking, f2 is the focal length of the second lens element, and f3 is the focal length of the third lens element.

### Claim 13 (depends on 12)

The optical lens system for image taking according to claim 12, wherein the second lens element and the third lens element are made of plastic, and the image-side surface of the third lens element comprises at least one inflection point.

### Claim 14 (depends on 13)

The optical lens system for image taking according to claim 13, wherein the optical lens system for image taking satisfies the following condition:
1.00<f/f1<1.47;
wherein f is the focal length of the optical lens system for image taking, and f1 is the focal length of the first lens element.

### Claim 15 (depends on 13)

The optical lens system for image taking according to claim 13, wherein the optical lens system for image taking satisfies the following condition:
0<|f/f3|<0.45;
wherein f is the focal length of the optical lens system for image taking, and f3 is the focal length of the third lens element.

### Claim 16 (depends on 14)

The optical lens system for image taking according to claim 14, wherein the optical lens system for image taking satisfies the following condition:
0.7<T12/T23<1.8;
wherein T12 is the axial distance between the first lens element and the second lens element, and T23 is the axial distance between the second lens element and the third lens element.

### Claim 17 (depends on 15)

The optical lens system for image taking according to claim 15, wherein the optical lens system for image taking satisfies the following condition:
−0.25<R3/R4<0.0;
wherein R3 is the curvature radius of the object-side surface of the second lens element, R4 is the curvature radius of the image-side surface of the second lens element.

### Claim 18 (depends on 15)

The optical lens system for image taking according to claim 15, wherein the first lens element comprises a convex image-side surface.

### Claim 19 (depends on 13)

The optical lens system for image taking according to claim 13, wherein the optical lens system for image taking satisfies the following condition:
29<V1−V2<50;
wherein V1 is the Abbe number of the first lens element, and V2 is the Abbe number of the second lens element.

### Claim 20 (depends on 13)

The optical lens system for image taking according to claim 13, wherein the optical lens system for image taking satisfies the following condition:
N2>1.60; and
V2<25;
wherein N2 is the refractive index of the second lens element, and V2 is the Abbe number of the second lens element.

### Claim 21 (depends on 13)

The optical lens system for image taking according to claim 13, wherein the optical lens system for image taking further comprises an image plane and the optical lens system for image taking satisfies the following condition:
TTL/ImgH<2.0;
wherein TTL is the axial distance between the object-side surface of the first lens element and the image plane, and ImgH is a maximal image height of the optical lens system for image taking.