Imaging lens and imaging apparatus provided with the same

Patent metadata

Field	Value
Publication number	US-2016004034-A1
Application number	US-201514850927-A
Country	US
Kind code	A1
Filing date	Sep 10, 2015
Priority date	Mar 29, 2013
Publication date	Jan 7, 2016
Grant date	—

Abstract

An imaging lens consists of five lenses consisting of, in order from the object side, a first lens having a positive refractive power and having a shape with a convex surface toward the object side, a second lens having a biconcave shape, a third lens having a biconvex shape, a fourth lens having a positive refractive power, and a fifth lens having a negative refractive power, having a shape with a concave surface toward the image side, and having at least one inflection point on the image-side surface thereof. The imaging lens satisfies a given condition expression.

First claim

What is claimed is:

1 . An imaging lens consisting of five lenses consisting of; in order from an object side:
a first lens having a positive refractive power and having a shape with a convex surface toward the object side; a second lens having a biconcave shape; a third lens having a biconvex shape; a fourth lens having a positive refractive power; and a fifth lens having a negative refractive power, having a shape with a concave surface toward the image side, and having at least one inflection point on the image-side surface thereof, wherein the condition expressions below are satisfied:
0.13< d 45/ f 1234<0.3   (1), and

0.5< f ·tan ω/ R 5 r< 10   (5),

where d 45 is a distance between the fourth lens and the fifth lens along an optical axis, f 1234 is a combined focal length of the first to the fourth lenses, f is a focal length of the entire system, ω is a half angle of view, and R 5 r is a radius of curvature of the image-side surface of the fifth lens.

2 . The imaging lens as claimed in claim 1 , wherein the condition expression below is further satisfied:
0.11< d 45/ f< 0.3   (2),

where d 45 is a distance between the fourth lens and the fifth lens along the optical axis, and f is a focal length of the entire system.

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

where R 2 f is a paraxial radius of curvature of the object-side surface of the second lens, R 2 r is a paraxial radius of curvature of the image-side surface of the second lens, and |R 2 f |>|R 2 r|.

4 . The imaging lens as claimed in claim 1 , wherein the condition expression below is further satisfied:
−1<( R 5 f+R 5 r )/( R 5 f−R 5 r )<0.08   (4),

where R 5 f is a paraxial radius of curvature of the object-side surface of the fifth lens, and R 5 r is a paraxial radius of curvature of the image-side surface of the fifth lens.

5 . The imaging lens as claimed in claim 1 , wherein the condition expression below is further satisfied:
0.7< f/f 12<1.2   (6),

where f is a focal length of the entire system, and f 12 is a combined focal length of the first lens and the second lens.

6 . The imaging lens as claimed in claim 1 , wherein the condition expression below is further satisfied:
0.8< f/f 1<2.5   (7),

where f is a focal length of the entire system, and f 1 is a focal length of the first lens.

7 . The imaging lens as claimed in claim 1 , wherein the condition expression below is further satisfied:
−2.5< f/f 5<−1.2   (8),

where f is a focal length of the entire system, and f 5 is a focal length of the fifth lens.

8 . The imaging lens as claimed in claim 1 , wherein the condition expression below is further satisfied:
−2.5< f/f 2<−0.7   (9),

where f is a focal length of the entire system, and f 2 is a focal length of the second lens.

9 . The imaging lens as claimed in claim 1 , further comprising an aperture stop disposed on the object side of the object-side surface of the second lens.

10 . The imaging lens as claimed in claim 1 , wherein the condition expression below is further satisfied:
0.14< d 45/ f 1234<0.25   (1-1),

where d 45 is a distance between the fourth lens and the fifth lens along the optical axis, and f 1234 is a combined focal length of the first to the fourth lenses.

11 . The imaging lens as claimed in claim 1 , wherein the condition expression below is further satisfied:
0.11< d 45/ f< 0.25   (2-1),

where d 45 is a distance between the fourth lens and the fifth lens along the optical axis, and f is a focal length of the entire system.

12 . The imaging lens as claimed in claim 1 , wherein the condition expression below is further satisfied:
0.1<( R 2 f+R 2 r )/( R 2 f−R 2 r )<0.35   (3-1),

where R 2 f is a paraxial radius of curvature of the object-side surface of the second lens, R 2 r is a paraxial radius of curvature of the image-side surface of the second lens, and |R 2 f |>|R 2 r|.

13 . The imaging lens as claimed in claim 1 , wherein the condition expression below is further satisfied:
−0.5<( R 5 f+R 5 r )/( R 5 f−R 5 r )<0.07   (4-1),

where R 5 f is a paraxial radius of curvature of the object-side surface of the fifth lens, and R 5 r is a paraxial radius of curvature of the image-side surface of the fifth lens.

14 . The imaging lens as claimed in claim 1 , wherein the condition expression below is further satisfied:
0.7< f ·tan ω/ R 5 r< 3   (5-1),

where f is a focal length of the entire system, ω is a half angle of view, and R 5 r is a radius of curvature of the image-side surface of the fifth lens.

15 . The imaging lens as claimed in claim 1 , wherein the condition expression below is further satisfied:
0.8< f/f 12<1   (6-1)

where f is a focal length of the entire system, and f 12 is a combined focal length of the first lens and the second lens.

16 . The imaging lens as claimed in claim 1 , wherein the condition expression below is further satisfied:
1< f/f 1<2   (7-1),

where f is a focal length of the entire system, and f 1 is a focal length of first lens.

17 . The imaging lens as claimed in claim 1 , wherein the condition expression below is further satisfied:
−2< f/f 5<−1.4   (8-1),

where f is a focal length of the entire system, and f 5 is a focal length of the fifth lens.

18 . The imaging lens as claimed in claim 1 , wherein the condition expression below is further satisfied:
−1.3< f/f 2<−0.8   (9-1),

where f is a focal length of the entire system, and f 2 is a focal length of the second lens.

19 . An imaging apparatus comprising the imaging lens as claimed in claim 1 .

Assignees

• Fujifilm Corp

Inventors

• Nishihata Sumihiro
• Cho Michio

Classifications

• G02B9/60 Primary

  having five components only · CPC title

• G02B13/0045 Primary

  having five or more lenses · CPC title

• G02B13/18

  with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration {(G02B13/002 takes precedence)} · CPC title