Imaging lens and imaging device provided with the same

Patent metadata

Field	Value
Publication number	US-9335515-B2
Application number	US-201414488314-A
Country	US
Kind code	B2
Filing date	Sep 17, 2014
Priority date	Sep 20, 2013
Publication date	May 10, 2016
Grant date	May 10, 2016

Abstract

An imaging lens with five lenses arranged as, in order from the object side, a first lens with a positive refractive power and a meniscus shape with a convex surface directed toward the object side, a second lens with a biconcave shape, a third lens with a negative refractive power and a meniscus shape with a convex surface toward the image side, a fourth lens with a positive refractive power, and a fifth lens with a negative refractive power, where an image-side surface of the fifth lens includes a concave surface and at least one inflection point, and a predetermined conditional expression is satisfied that achieves a high imaging performance from a central angle of view to a peripheral angle of view, while achieving reduction of an entire length of the lens.

First claim

What is claimed is:

1. An imaging lens with five lenses, consisting of, ordered as follows from an object side:
a first lens having a positive refractive power and having a meniscus shape with a convex surface toward the object side;
a second lens having a biconcave shape;
a third lens having a negative refractive power and having a meniscus shape with a convex surface toward an image side;
a fourth lens having a positive refractive power; and
a fifth lens having a negative refractive power, wherein an image-side surface of the fifth lens includes a concave surface and at least one inflection point,
wherein the conditional expression below is satisfied:
0.2< f/f 4<1.38  (1),

where f is a focal length of the entire system, and f4 is a focal length of the fourth lens, and
wherein the conditional expression below is further satisfied:
−0.6<( L 1 r+L 2 f )/( L 1 r−L 2 f )<0.11  (3),

where L1r is a paraxial radius of curvature of an image-side surface of the first lens, and L2f is a paraxial radius of curvature of an object-side surface of the second lens.

2. The imaging lens as claimed in claim 1 , wherein the conditional expression below is further satisfied:
−0.86<( L 1 f−L 1 r )/( L 1 f+L 1 r )<−0.1  (2),

where L1f is a paraxial radius of curvature of an object-side surface of the first lens, and L1r is a paraxial radius of curvature of an image-side surface of the first lens.

3. The imaging lens as claimed in claim 2 , wherein the conditional expression below is further satisfied:
−0.85<( L 1 f−L 1 r )/( L 1 f+L 1 r )<−0.5  (2-1),

where L1f is a paraxial radius of curvature of the object-side surface of the first lens, and L1r is a paraxial radius of curvature of the image-side surface of the first lens.

4. The imaging lens as claimed in claim 3 , wherein the conditional expression below is further satisfied:
−0.84<( L 1 f−L 1 r )/( L 1 f+L 1 r )<−0.6  (2-2),

where L1f is a paraxial radius of curvature of the object-side surface of the first lens, and L1r is a paraxial radius of curvature of the image-side surface of the first lens.

5. The imaging lens as claimed in claim 1 , wherein the conditional expression below is further satisfied:
0.2< f/f 34<1.3  (4),

where f34 is a combined focal length of the third lens and the fourth lens.

6. The imaging lens as claimed in claim 5 , wherein the conditional expression below is further satisfied:
0.6< f/f 34<1.28  (4-1),

where f34 is a combined focal length of the third lens and the fourth lens.

7. The imaging lens as claimed in claim 1 , wherein the conditional expression below is further satisfied:
0.21< f/L 1 r< 1  (5),

where L1r is a paraxial radius of curvature of an image-side surface of the first lens.

8. The imaging lens as claimed in claim 1 , wherein the conditional expression below is further satisfied:
1.1< f/f 1234<1.42  (6),

where f1234 is a combined focal length of the first to the fourth lenses.

9. The imaging lens as claimed in claim 8 , wherein the conditional expression below is further satisfied:
1.2< f/f 1234<1.42  (6-1),

where f1234 is a combined focal length of the first to the fourth lenses.

10. The imaging lens as claimed in claim 1 , wherein the conditional expression below is further satisfied:
0.4< f ·tan ω/ L 5 r< 10  (7),

where ω is a half angle of view, and L5r is a paraxial radius of curvature of an image-side surface of the fifth lens.

11. The imaging lens as claimed in claim 10 , wherein the conditional expression below is further satisfied:
0.5< f ·tan ω/ L 5 r< 5  (7-1),

where ω is a half angle of view, and L5r is a paraxial radius of curvature of the image-side surface of the fifth lens.

12. The imaging lens as claimed in claim 1 , wherein the conditional expression below is further satisfied:
1.3< TTL /( f ·tan ω)<1.9  (8),

where TTL is a distance from an object-side surface of the first lens to an image plane, where a back focus portion of the distance is an equivalent air distance, and co is a half angle of view.

13. The imaging lens as claimed in claim 1 , wherein the fourth lens has a meniscus shape with a convex surface toward the image side.

14. The imaging lens as claimed in claim 1 , wherein the fifth lens has a meniscus shape with a concave surface toward the image side.

15. The imaging lens as claimed in claim 1 , wherein the conditional expression below is further satisfied:
0.6< f/f 4<1.34  (1-1).

16. The imaging lens as claimed in claim 1 , wherein the conditional expression below is further satisfied:
−0.45<( L 1 r+L 2 f )/( L 1 r−L 2 f )<0.105  (3-1),

where L1r is a paraxial radius of curvature of the image-side surface of the first lens, and L2f is a paraxial radius of curvature of the object-side surface of the second lens.

17. An imaging device comprising the imaging lens as claimed in claim 1 .

18. An imaging lens with five lenses, consisting of, ordered as follows from an object side:
a first lens having a positive refractive power and having a meniscus shape with a convex surface toward the object side;
a second lens having a biconcave shape;
a third lens having a negative refractive power and having a meniscus shape with a convex surface toward an image side;
a fourth lens having a positive refractive power; and
a fifth lens having a negative refractive power, wherein an image-side surface of the fifth lens includes a concave surface and at least one inflection point,
wherein the conditional expression below is satisfied:
0.2< f/f 4<1.38  (1),

where f is a focal length of the entire system, and f4 is a focal length of the fourth lens, and
wherein the conditional expression below is further satisfied:
0.23< f/L 1 r< 0.8  (5-1),

where L1r is a paraxial radius of curvature of the image-side surface of the first lens.

19. An imaging lens with five lenses, consisting of, ordered as follows from an object side:
a first lens having a positive refractive power and having a meniscus shape with a convex surface toward the object side;
a second lens having a biconcave shape;
a third lens having a negative refractive power and having a meniscus shape with a convex surface toward an image side;
a fourth lens having a positive refractive power; and
a fifth lens having a negative refractive power, wherein an image-side surface of the fifth lens includes a concave surface and at least one inflection point,
wherein the conditional expression below is satisfied:
1< f/f 4<1.32  (1-2)

where f is a focal length of the entire system, and f4 is a focal length of the fourth lens.

Assignees

• Fujifilm Corp

Inventors

• Ota Motoari
• Tanaka Takuya
• Nishihata Sumihiro
• Cho Michio

Classifications

• G02B9/60

  having five components only · CPC title

• G02B13/0045 Primary

  having five or more lenses · CPC title