Image lens system

• US 8,792,185 B2
• Filed: 08/24/2012
• Issued: 07/29/2014
• Est. Priority Date: 05/18/2012
• Status: Active Grant

• Current Assignee: Largan Precision Co Limited (Largan Precision)
• Original Assignee: Largan Precision Co Limited (Largan Precision)
• Inventors: Hsu, Chih-Wen, Chou, Ming-Ta, Tsai, Tsung-Han
• Primary Examiner(s): Jones, James
• Application Number:
  US13/594,197
• Publication Number:
  US 20130308206A1
• Time in Patent Office: 704 Days
• Field of Search: 359/714
• US Class Current: 359/714
• CPC Class Codes: G02B 13/0045 having five or more 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 image lens system includes, in order from an object side to an image side, a first lens element with negative refractive power including a concave image-side surface; a second lens element with positive refractive power including a convex object-side surface; a third lens element with negative refractive power including an object-side surface and a concave image-side surface, the object-side surface and the image-side surface being aspheric; a fourth lens element with positive refractive power including a convex object-side surface and a convex image-side surface; and a fifth lens element with negative refractive power including a convex object-side surface and a concave image-side surface, the object-side surface and the image-side surface being aspheric, the fifth lens element having at least one inflection point.

Claims

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

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

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

a third lens element with negative refractive power comprising an object-side surface and a concave image-side surface, the object-side surface and the image-side surface being aspheric;

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

a fifth lens element with negative refractive power comprising a convex object-side surface and a concave image-side surface, the object-side surface and the image-side surface being aspheric, the fifth lens element having at least one inflection point;

the image lens system satisfying the following condition;

0≦

R₆|R₅|<

1.0

wherein 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 lens element.

2. The image lens system according to claim 1, wherein the image lens system satisfies the following condition:

|R₆/R₇|<

0.9

wherein R₆ is the curvature radius of the image-side surface of the third lens element, and R₇ is the curvature radius of the object-side surface of the fourth lens element.

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

0≦

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.

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

0.3<

R₂/T₁₂<

1.6

wherein R₂ is the curvature radius of the image-side surface of the first lens element, and T₁₂ is the axial distance between the first lens element and the second lens element.

5. The image lens system according to claim 2, wherein the image lens system satisfies the following condition:

1.5<

(V₄+V₃)/(V₄−

V₃)<

3.0

wherein V₃ is the Abbe number of the third lens element, and V₄ is the Abbe number of the fourth lens element.

6. The image lens system according to claim 2, wherein the object-side surface of the third lens element is convex.

7. The image lens system according to claim 1, wherein the image lens system satisfies the following condition:

0<

(R₇+R₈)/(R₇−

R₈)<

1.0

wherein R₇ is the curvature radius of the object-side surface of the fourth lens element, and R₈ is the curvature radius of the image-side surface of the fourth lens element.

8. The image lens system according to claim 7, wherein the image lens system satisfies the following condition:

1.7<

(R₉+R₁₀)/(R₉−

R₁₀)<

5.3

wherein R₉ is the curvature radius of the object-side surface of the fifth lens element, and R₁₀ is the curvature radius of the image-side surface of the fifth lens element.

9. The image lens system according to claim 7, wherein at least two of the first lens element, the second lens element, the third lens element, the fourth lens element and the fifth element are made of plastic.

10. The image lens system according to claim 7, wherein the image lens system satisfies the following condition:

80(degrees;

deg.)<

FOV<

160(deg.)

wherein FOV is the maximal field of view in the image lens system.

11. The image lens system according to claim 7, wherein the first lens element comprises an object-side surface and the image lens system satisfies the following condition:

0.15<

Dr₅r₁₀/TD<

0.40

wherein Dr₅r₁₀ is the axial distance between the object-side surface of the third lens element and the image-side surface of the fifth lens element, and TD is the axial distance between the object-side surface of the first lens element and the image-side surface of the fifth lens element.

12. The image lens system according to claim 1, wherein the image lens system satisfies the following condition:

0.3<

f/f₁₂<

1.0

wherein f is the focal length of the image lens system, and f₁₂ is the composite focal length of the first lens element and the second lens element.

13. The image lens system according to claim 1, wherein the image lens system satisfies the following condition:

0<

f₁₂/f₃₄₅<

1.0

wherein f₁₂ is the composite focal length of the first lens element and the second lens element, and f₃₄₅ is the composite focal length of the third lens element, the fourth lens element and the fifth lens element.

14. An image lens system comprising, in order from an object side to an image side:

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

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

a third lens element with negative refractive power comprising an object-side surface and a concave image-side surface, the object-side surface and the image-side surface being aspheric;

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

a fifth lens element with negative refractive power comprising a convex object-side surface and a concave image-side surface, the fifth lens element being made of plastic, the object-side surface and the image-side surface being aspheric, the fifth lens element having at least one inflection point;

the image lens system satisfying the following condition;

0≦

R₆/|R₅|<

1.0;

0.5(millimeters;

mm)<

f/tan(HFOV)<

3.0(mm)

wherein R₅ is the curvature radius of the object-side surface of the third lens element, R₆ is the curvature radius of the image-side surface of the third lens element, f is the focal length of the image lens system, and HFOV is a half of the maximal field of view in the image lens system.

15. The image lens system according to claim 14, wherein the image lens system satisfies the following condition:

0.30<

f/f₁₂<

1.0

wherein f is the focal length of the image lens system, and f₁₂ is the composite focal length of the first lens element and the second lens element.

16. The image lens system according to claim 14, wherein the image lens system satisfies the following condition:

0<

f₁₂/f₃₄₅<

1.0

wherein f₁₂ is the composite focal length of the first lens element and the second lens element, and f₃₄₅ is the composite focal length of the third lens element, the fourth lens element and the fifth lens element.

17. The image lens system according to claim 14, wherein the object-side surface of the third lens element is convex.

18. The image lens system according to claim 14, wherein the second lens element comprises an image-side surface and the image lens system satisfies the following condition:

0≦

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.

19. The image lens system according to claim 14, wherein the fourth lens element comprises an object-side surface and the image lens system satisfies the following condition:

|R₆/R₇|<

0.9

wherein R₆ is the curvature radius of the image-side surface of the third lens element, and R₇ is the curvature radius of the object-side surface of the fourth lens element.

20. The image lens system according to claim 14, wherein the image lens system satisfies the following condition:

1.5<

(V₄+V₃)/(V₄−

V₃)<

3.0

wherein V₃ is the Abbe number of the third lens element, and V₄ is the Abbe number of the fourth lens element.

21. An image lens system comprising, in order from an object side to an image side:

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

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

a third lens element with negative refractive power comprising a convex object-side surface and a concave image-side surface, the object-side surface and the image-side surface being aspheric;

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

a fifth lens element with negative refractive power comprising a convex object-side surface and a concave image-side surface, the fifth lens element being made of plastic, the object-side surface and the image-side surface being aspheric, the fifth lens element having at least one inflection point;

the image lens system satisfying the following condition;

0≦

R₆/|R₅|<

1.0

wherein 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 lens element.

22. The image lens system according to claim 21, wherein fourth lens element comprises an object-side surface and the image lens system satisfies the following condition:

0<

(R₇+R₈)/(R₇−

R₈)<

1.0

wherein R₇ is the curvature radius of the object-side surface of the fourth lens element, and R₈ is the curvature radius of the image-side surface of the fourth lens element.

23. The image lens system according to claim 21, wherein the fourth lens element comprises an object-side surface and the image lens system satisfies the following condition:

|R₆/R₇|<

0.9

wherein R₆ is the curvature radius of the image-side surface of the third lens element, and R₇ is the curvature radius of the object-side surface of the fourth lens element.

24. The image lens system according to claim 21, wherein the second lens element comprises an image-side surface and the image lens system satisfies the following condition:

0≦

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.

25. The image lens system according to claim 21, wherein the image lens system satisfies the following condition:

0.30<

f/f₁₂<

1.0

wherein f is the focal length of the image lens system, and f₁₂ is the composite focal length of the first lens element and the second lens element.

26. The image lens system according to claim 21, wherein the image lens system satisfies the following condition:

0<

f₁₂/f₃₄₅<

1.0

wherein f₁₂ is the composite focal length of the first lens element and the second lens element, and f₃₄₅ is the composite focal length of the third lens element, the fourth lens element and the fifth lens element.