OPTICAL LENS SYSTEM FOR IMAGE TAKING

• US 20130120859A1
• Filed: 04/03/2012
• Published: 05/16/2013
• Est. Priority Date: 11/11/2011
• Status: Active Grant

• Current Assignee: Largan Precision Co Limited (Largan Precision)
• Original Assignee: Largan Precision Co Limited (Largan Precision)
• Inventors: Tsai, Tsung-Han, Chou, Ming-Ta
• Granted Patent: US 8,724,239 B2
• Time in Patent Office: Days
• US Class Current: 359/716
• CPC Class Codes: G02B 13/0035 having three lenses
• CPC Class Codes: G02B 13/06 Panoramic objectives; So-called "sky lenses" including panoramic objectives having reflecting surfaces
• CPC Class Codes: G02B 13/18 with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration G02B13/002 takes precedence

Abstract

An optical lens system for image taking includes, in order from an object side to an image side, a first lens element with negative refractive power having a concave object-side surface and a concave image-side surface, a second lens element with positive refractive power having a convex image-side surface, and a third lens element with negative refractive power having a concave image-side surface of the third lens element near an optical axis and a convex image-side surface of the third lens element away from the optical axis. Both the object-side surface and the image-side surface of the third lens element are aspheric. The third lens element is made of plastic.

Claims

1. An optical lens system for image taking comprising, in order from an object side to an image side:

a first lens element with negative refractive power comprising a concave object-side surface and a concave image-side surface;

a second lens element with positive refractive power comprising a convex image-side surface; and

a third lens element with negative refractive power comprising an object-side surface, a concave image-side surface near an optical axis and a convex image-side surface away from the optical axis, both the object-side surface and the image-side surface being aspheric, and the third lens element being made of plastic;

the optical lens system for image taking satisfying the following condition;

0<

T₂₃/T₁₂<

0.7; and

0<

(R₅+R₆)/(R₅−

R₆)<

4.0;

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, R₅ is the curvature radius of the object-side surface of the third lens element, and R₆ is the curvature radius of the image-side surface of the third element.

2. The optical lens system for image taking according to claim 1, wherein the second lens element comprises an object-side surface and the optical lens system for image taking satisfies the following condition:

0<

(R₃+R₄)/(R₃−

R₄)<

2.0;

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.

3. The optical lens system for image taking according to claim 2, wherein the optical lens system for image taking satisfies the following condition:

28<

V₂−

V₃<

45;

wherein V₂ is the Abbe number of the second lens element, and V₃ is the Abbe number of the third lens element.

4. The optical lens system for image taking according to claim 2, wherein the optical lens system for image taking satisfies the following condition:

0<

T₂₃/T₁₂<

0.35;

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.

5. 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<

f/f₂₃<

1.3;

wherein f is the focal length of the optical lens system for image taking, and f₂₃ is the combined focal length of the second lens element and the third lens element.

6. The optical lens system for image taking according to claim 2, wherein the optical lens system for image taking satisfies the following condition:

75°

(degree)<

FOV<

140°

;

wherein FOV is the maximal field of view of the optical lens system for image taking.

7. 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:

2.5<

TTL/CT₂<

5.5;

wherein TTL is the axial distance between the object-side surface of the first lens element and the image plane, and CT₂ is the central thickness of the second lens element.

8. The optical lens system for image taking according to claim 1, wherein the optical lens system for image taking satisfies the following condition:

0.8 (millimeter, mm)<

TD<

3.0 mm;

wherein TD is the axial distance between the object-side surface of the first lens element and the image-side surface of the third lens element.

9. The optical lens system for image taking according to claim 1, wherein there are a concave object-side surface of the first lens element near the optical axis and a convex object-side surface of the first lens element away from the optical axis.

10. The optical lens system for image taking according to claim 9, wherein the optical lens system for image taking satisfies the following condition:

1.70<

TD/f<

3.0;

wherein TD is the axial distance between the object-side surface of the first lens element and the image-side surface of the third lens element, and f is the focal length of the optical lens system for image taking.

11. An optical lens system for image taking comprising, in order from an object side to an image side:

a first lens element with negative refractive power comprising a concave object-side surface of the first lens element near an optical axis and a convex object-side surface of the first lens element away from the optical axis;

a second lens element with positive refractive power comprising a convex object-side surface and a convex image-side surface; and

a third lens element with negative refractive power comprising an object-side surface, a concave image-side surface near the optical axis and a convex image-side surface away from the optical axis, both the object-side surface and the image-side surface being aspheric, and the third lens element being made of plastic;

the optical lens system for image taking satisfying the following condition;

0<

T₂₃/T₁₂<

0.7; and

0<

(R₅+R₆)/(R₅−

R₆)<

4.0;

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, R₅ is the curvature radius of the object-side surface of the third lens element, and R₆ is the curvature radius of the image-side surface of the third element.

12. The optical lens system for image taking according to claim 11, wherein the optical lens system for image taking satisfies the following condition:

0<

(R₃+R₄)/(R₃−

R₄)<

1.0;

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.

13. The optical lens system for image taking according to claim 12, wherein the first lens element comprises an image-side surface and the optical lens system for image taking satisfies the following condition:

−

1.0<

(R₁+R₂)/(R₁−

R₂)<

1.0;

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.

14. The optical lens system for image taking according to claim 12, wherein the optical lens system for image taking satisfies the following condition:

1.70<

TD/f<

3.0;

wherein TD is the axial distance between the object-side surface of the first lens element and the image-side surface of the third lens element, and f is the focal length of the optical lens system for image taking.

15. The optical lens system for image taking according to claim 12, wherein the optical lens system for image taking satisfies the following condition:

75°

(degree)<

FOV<

140°

;

wherein FOV is the maximal field of view of the optical lens system for image taking.

16. The optical lens system for image taking according to claim 15, wherein the optical lens system for image taking satisfies the following condition:

0.8 (millimeter, mm)<

TD<

3.0 mm;

wherein TD is the axial distance between the object-side surface of the first lens element and the image-side surface of the third lens element.

17. The optical lens system for image taking according to claim 15, wherein the optical lens system for image taking satisfies the following condition:

0<

T₂₃/T₁₂<

0.35;

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.

18. An optical lens system for image taking comprising, in order from an object side to an image side:

a first lens element with negative refractive power comprising a concave object-side surface of the first lens element near an optical axis and a convex object-side surface of the first lens element away from the optical axis;

a second lens element with positive refractive power comprising a convex image-side surface; and

a third lens element with negative refractive power comprising a concave object-side surface, a concave image-side surface near the optical axis and a convex image-side surface away from the optical axis, both the object-side surface and the image-side surface being aspheric, and the third lens element being made of plastic;

the optical lens system for image taking satisfying the following condition;

0<

T₂₃/T₁₂<

0.7;

0<

(R₅+R₆)/(R₅−

R₆)<

1.0; and

0.8 (millimeter, mm)<

TD<

3.0 mm;

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, TD is the axial distance between the object-side surface of the first lens element and the image-side surface of the third lens element, R₅ is the curvature radius of the object-side surface of the third lens element, and R₆ is the curvature radius of the image-side surface of the third element.

19. The optical lens system for image taking according to claim 18, wherein the first lens element comprises an image-side surface, and the optical lens system for image taking satisfies the following condition:

−

1.0<

(R₁+R₂)/(R₁−

R₂)<

1.0;

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.

20. The optical lens system for image taking according to claim 18, wherein the optical lens system for image taking satisfies the following condition:

75°

(degree)<

FOV<

140°

;

wherein FOV is the maximal field of view of the optical lens system for image taking.

21. The optical lens system for image taking according to claim 18, wherein the optical lens system for image taking satisfies the following condition:

0.8<

f/f₂₃<

1.3;

wherein f is the focal length of the optical lens system for image taking, and f₂₃ is the combined focal length of the second lens element and the third lens element.

22. The optical lens system for image taking according to claim 18, wherein the optical lens system for image taking satisfies the following condition:

1.70<

TD/f<

3.0;

wherein TD is the axial distance between the object-side surface of the first lens element and the image-side surface of the third lens element, and f is the focal length of the optical lens system for image taking.