OPTICAL LENS SYSTEM

• US 20120087020A1
• Filed: 11/22/2011
• Published: 04/12/2012
• Est. Priority Date: 10/06/2010
• Status: Active Grant

• Current Assignee: Largan Precision Co Limited (Largan Precision)
• Original Assignee: Largan Precision Co Limited (Largan Precision)
• Inventors: Tang, Hsiang Chi, Tsai, Tsung Han, Huang, Hsin Hsuan
• Granted Patent: US 8,508,860 B2
• Time in Patent Office: Days
• US Class Current: 359/714
• CPC Class Codes: G02B 13/0045 having five or more lenses

Abstract

The present invention provides an optical lens system comprising, 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; a third lens element with positive refractive power having a convex object-side surface and a convex image-side surface; a fourth lens element; and a fifth lens element having a convex object-side surface and a concave image-side surface, the object-side and image-side surfaces thereof being aspheric and at least one inflection point being formed on the image-side surface. Such arrangement of optical elements can effectively minimize the size of the optical lens system, lower the sensitivity of the optical system, and obtain higher image resolution.

Claims

1. An optical lens system comprising, 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;

a third lens element with positive refractive power having a convex object-side surface and a convex image-side surface;

a fourth lens element; and

a fifth lens element having a convex object-side surface and a concave image-side surface, the object-side and image-side surfaces thereof being aspheric and at least one inflection point being formed on the image-side surface,

wherein the optical lens system is further provided with a stop disposed between an object and the third lens element, and an electronic sensor disposed at an image plane for the image formation of the object;

a focal length of the optical lens system is f;

a focal length of the third lens element is f3;

a distance on an optical axis between the stop and the electronic sensor is SL;

a distance on the optical axis between the object-side surface of the first lens element and the electronic sensor is TTL; and

they satisfy the following relations;

0.00<

f/f3<

1.90, and

0.7<

SL/TTL<

1.2.

2. The optical lens system according to claim 1, wherein the fourth lens element has a concave object-side surface and a convex image-side surface, at least one of the object-side and image-side surfaces of the fourth lens element is aspheric, and the fifth lens element is made of plastic.

3. The optical lens system according to claim 2, wherein the second lens element has a concave image-side surface.

4. The optical lens system according to claim 3, wherein the focal length of the optical lens system is f, a focal length of the first lens element is f1, and they satisfy the following relation:

1.00<

f/f1<

2.30.

5. The optical lens system according to claim 4, wherein the focal length of the optical lens system is f, the focal length of the first lens element is f1, and they satisfy the following relation:

1.30<

f/f1<

2.00.

6. The optical lens system according to claim 3, wherein the focal length of the optical lens system is f, the focal length of the third lens element is f3, and they satisfy the following relation:

0.00<

f/f3<

0.80.

7. The optical lens system according to claim 3, wherein an Abbe number of the first lens element is V1, an Abbe number of the second lens element is V2, and they satisfy the following relation:

28.0<

V1−

V2<

42.0.

8. The optical lens system according to claim 1, wherein an Abbe number of the second lens element is V2, an Abbe number of the third lens element is V3, and they satisfy the following relation:

|V2−

V3|<

12.0.

9. The optical lens system according to claim 3, wherein a thickness of the second lens element on the optical axis is CT2, the focal length of the optical lens system is f, and they satisfy the following relation:

0.02<

CT2/f<

0.15.

10. The optical lens system according to claim 3, wherein a radius of curvature of the object-side surface of the first lens element is R1, a radius of curvature of the image-side surface of the first lens element is R2, and they satisfy the following relation:

−

0.80<

R1/R2<

0.50.

11. The optical lens system according to claim 3, wherein a radius of curvature of the object-side surface of the fifth lens element is R9, a radius of curvature of the image-side surface of the fifth lens element is R10, and they satisfy the following relation:

|R10/R9|<

1.3.

12. The optical lens system according to claim 11, wherein the radius of curvature of the object-side surface of the fifth lens element is R9, the radius of curvature of the image-side surface of the fifth lens element is R10, and they satisfy the following relation:

|R10/R9|<

0.8.

13. The optical lens system according to claim 2, wherein the focal length of the optical lens system is f, the focal length of the third lens element is f3, a focal length of the fourth lens element is f4, a focal length of the fifth lens element is f5, and they satisfy the following relation:

|(f/f3)+(f/f4)+(f/f5)|<

0.5.

14. The optical lens system according to claim 3, wherein the second lens element has a concave object-side surface.

15. The optical lens system according to claim 3, wherein the distance on the optical axis between the stop and the electronic sensor is SL, the distance on the optical axis between the object-side surface of the first lens element and the electronic sensor is TTL, and they satisfy the following relation:

0.8<

SL/TTL<

0.98.

16. The optical lens system according to claim 1, wherein the distance on the optical axis between the object-side surface of the first lens element and the electronic sensor is TTL, half of a diagonal length of an effective pixel area of the electronic sensor is ImgH, and they satisfy the following relation:

TTL/ImgH<

2.10.

17. An optical lens system comprising, 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;

a third lens element with positive refractive power having a convex object-side surface and a convex image-side surface;

a fourth lens element with positive refractive power; and

a fifth lens element with negative refractive power having a convex object-side surface and a concave image-side surface, both of the object-side and image-side surfaces thereof being aspheric and at least one inflection point being formed on the image-side surface,

wherein the optical lens system is further provided with a stop disposed between an object and the third lens element, and an electronic sensor disposed at an image plane for the image formation of the object;

a focal length of the optical lens system is f;

a focal length of the first lens element is f1;

a distance on an optical axis between the stop and the electronic sensor is SL;

a distance on the optical axis between the object-side surface of the first lens element and the electronic sensor is TTL; and

they satisfy the following relations;

1.00<

f/f1<

2.30, and

0.7<

SL/TTL<

1.2.

18. The optical lens system according to claim 17, wherein the fourth lens element has a concave image-side surface and a convex image-side surface, at least one of the object-side and image-side surfaces of the fourth lens element is aspheric, and the fifth lens element is made of plastic.

19. The optical lens system according to claim 18, wherein the focal length of the optical lens system is f, the focal length of the first lens element is f1, and they satisfy the following relation:

1.30<

f/f1<

2.00.

20. The optical lens system according to claim 18, wherein the focal length of the optical lens system is f, a focal length of the third lens element is f3, and they satisfy the following relation:

0.00<

f/f3<

0.80.

21. The optical lens system according to claim 18, wherein an Abbe number of the first lens element is V1, an Abbe number of the second lens element is V2, and they satisfy the following relation:

28.0<

V1−

V2<

42.0.

22. The optical lens system according to claim 18, wherein a focal length of the fourth lens element is f4, a focal length of the fifth lens element is f5, and they satisfy the following relation:

0.4<

|f4/f5|<

1.6.

23. The optical lens system according to claim 18, wherein the focal length of the optical lens system is f, a focal length of the third lens element is f3, a focal length of the fourth lens element is f4, a focal length of the fifth lens element is f5, and they satisfy the following relation:

|(f/f3)+(f/f4)+(f/f5)|<

0.5.

24. The optical lens system according to claim 18, wherein the distance on the optical axis between the stop and the electronic sensor is SL, the distance on the optical axis between the object-side surface of the first lens element and the electronic sensor is TTL, and they satisfy the following relation:

0.8<

SL/TTL<

0.98.

25. The optical lens system according to claim 18, wherein a radius of curvature of the object-side surface of the fifth lens element is R9, a radius of curvature of the image-side surface of the fifth lens element is R10, and they satisfy the following relation:

|R10/R9|<

0.8.

26. The optical lens system according to claim 17, wherein the second lens element has a concave object-side surface and a concave image-side surface.

27. The optical lens system according to claim 17, wherein the distance on the optical axis between the object-side surface of the first lens element and the electronic sensor is TTL, half of a diagonal length of an effective pixel area of the electronic sensor is ImgH, and they satisfy the following relation:

TTL/ImgH<

2.10.