Optical imaging lens system

• US 8,310,768 B2
• Filed: 11/22/2010
• Issued: 11/13/2012
• Est. Priority Date: 09/16/2010
• Status: Active Grant

• Current Assignee: Largan Precision Co Limited (Largan Precision)
• Original Assignee: Largan Precision Co Limited (Largan Precision)
• Inventors: Lin, Ming Ching, Huang, Hsin Hsuan
• Primary Examiner(s): Collins, Darryl J
• Application Number:
  US12/951,428
• Publication Number:
  US 20120069455A1
• Time in Patent Office: 722 Days
• Field of Search: 359/708, 359/713, 359/714, 359754-758, 359763-766
• US Class Current: 359/714
• CPC Class Codes: G02B 13/0045 having five or more lenses

Abstract

This invention provides an optical imaging lens system including five lens elements with refractive power, in order from an object side toward 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 having a convex object-side surface and a concave image-side surface, a fourth lens element having both surfaces being aspheric, a fifth lens element having a concave image-side surface with at least one inflection point formed thereon. By such arrangement, the total track length and the sensitivity of the optical imaging lens system can be reduced while achieving high image resolution.

Claims

1. An optical imaging lens system comprising five lens elements with refractive power, 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 having a convex object-side surface and a concave image-side surface;

a fourth lens element having both surface being aspheric; and

a fifth lens element having a concave image-side surface with at least one inflection point formed thereon;

wherein the optical imaging lens system further comprises a stop and an electronic sensor on which an object is imaged;

wherein a focal length of the optical imaging lens system is f, a focal length of the first lens element is f1, a focal length of the fourth lens element is f4, a thickness of the fourth lens element on the optical axis is CT4, a thickness of the fifth lens element on the optical axis is CT5, a distance on the 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 relation;

0.28≦

f/f1−

f/f4<

1.5;

0.8<

CT4/CT5<

1.5; and

0.7<

SL/TTL<

1.1.

2. The optical imaging lens system according to claim 1, wherein the object-side and image-side surfaces of the third lens element are both aspheric, and the fourth lens element has a concave object-side surface and a convex image-side surface.

3. The optical imaging lens system according to claim 2, 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 relation:

30<

V1−

V2<

42.

4. The optical imaging lens system according to claim 3, wherein an on-axis spacing between the second lens element and the third lens element is T23, a thickness of the second lens element on the optical axis is CT2, and they satisfy the relation:

0.9<

T23/CT2<

2.0.

5. The optical imaging lens system according to claim 2, 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 the diagonal length of the effective pixel area of the electronic sensor is ImgH, and they satisfy the relation:

TTL/ImgH<

1.80.

6. The optical imaging lens system according to claim 2, wherein at least one inflection point is formed on at least one surface of the object-side and image-side surfaces of the third lens elements, and the third and fifth lens elements are made of plastic.

7. The optical imaging lens system according to claim 6, wherein the second lens element has a concave image-side surface.

8. The optical imaging lens system according to claim 7, wherein the focal length of the optical imaging lens system is f, a focal length of the third lens element is f3, and they satisfy the relation:

−

0.5<

f/f3<

0.6.

9. The optical imaging lens system according to claim 8, wherein an air clearance exists between each lens element, and the focal length of the optical imaging lens system is f, the focal length of the third lens element is f3, and they satisfy the relation:

−

0.2<

f/f3<

0.5.

10. The optical imaging lens system according to claim 9, 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 relation:

−

0.3<

R1/R2<

0.3.

11. The optical imaging lens system according to claim 8, 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 relation:

0.8<

SL/TTL <

1.0.

12. The optical imaging lens system according to claim 11, wherein the focal length of the optical imaging lens system is f, the focal length of the fourth lens element is f4, a focal length of the fifth lens element is f5, and they satisfy the relation:

1.8<

|f/f4|+|f/f5|<

3.0.

13. The optical imaging lens system according to claim 8, the intersection of the image-side surface of the fourth lens element and the optical axis is T2, the farthest point of the effective light entry area on the image-side surface of the fourth lens element is P2, the distance on the optical axis between T2 and the vertical projection of P2 on the optical axis is SAG42, the vertical distance between P2 and the optical axis is Y42, and they satisfy the relation:

0.4<

SAG42/Y42<

0.7.

14. An optical imaging lens system comprising five lens elements with refractive power, 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 having a concave image-side surface;

a fourth lens element with positive refractive power, at least one of the object-side and image-side surfaces thereof being aspheric; and

a fifth lens element with negative refractive power having a concave image-side surface, and at least one of the object-side and image-side surfaces thereof being aspheric;

wherein the optical imaging lens system further comprises a stop and an electronic sensor on which an object is imaged;

wherein a focal length of the optical imaging lens system is f, a focal length of the fourth lens element is f4, a focal length of the fifth lens element is f5, an on-axis spacing between the second lens element and the third lens element is T23, a thickness of the second lens element on the optical axis is CT2, a distance on the 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 relation;

1.8<

|f/f4|+|f/f5|<

3.0;

1.16≦

T23/CT2<

2.5; and

0.7<

SL/TTL<

1.1.

15. The optical imaging lens system according to claim 14, wherein the focal length of the optical imaging lens system is f, a focal length of the third lens element is f3, and they satisfy the relation:

−

0.5<

f/f3<

0.6.

16. The optical imaging lens system according to claim 15, wherein the third lens element has a convex object-side surface, and at least one inflection point is formed on at least one of the object-side and image-side surfaces of the fifth lens element.

17. The optical imaging lens system according to claim 16, wherein at least one inflection point is formed on at least one of the object-side and image-side surfaces of the third lens element, the fourth lens element has a concave object-side surface and a convex image-side surface, and the fifth lens element is made of plastic.

18. The optical imaging lens system according to claim 17, wherein a thickness of the fourth lens element on the optical axis is CT4, a thickness on the optical axis of the fifth lens element is CT5, and they satisfy the relation:

0.8<

CT4/CT5<

1.5.

19. The optical imaging lens system according to claim 17, wherein the focal length of the optical imaging lens system is f, the focal length of the third lens element is f3, and they satisfy the relation:

−

0.2<

f/f3<

0.5.

20. The optical imaging lens system according to claim 17, the intersection of the image-side surface of the fourth lens element and the optical axis is T2, the farthest point of the effective light entry area on the image-side surface of the fourth lens element is P2, the distance on the optical axis between T2 and the vertical projection of P2 on the optical axis is SAG42, the vertical distance between P2 and the optical axis is Y42, and they satisfy the relation:

0.4<

SAG42/Y42<

0.7.

21. The optical imaging lens system according to claim 17, wherein the focal length of the optical imaging lens system is f, a focal length of the first lens element is f1, the focal length of the fourth lens element is f4, and they satisfy the relation:

0<

f/f1−

f/f4<

1.5.