Imaging lens and imaging apparatus equipped with the imaging lens

Patent metadata

Field	Value
Publication number	US-2016004048-A1
Application number	US-201514857759-A
Country	US
Kind code	A1
Filing date	Sep 17, 2015
Priority date	Mar 26, 2013
Publication date	Jan 7, 2016
Grant date	—

Abstract

An imaging lens is constituted essentially by six lenses, including, in order from the object side to the image side: a first lens having a positive refractive power and a convex surface toward the object side; a second lens having a negative refractive power; a third lens having a positive refractive power and is of a biconvex shape; a fourth lens having a positive refractive power; a fifth lens having a negative refractive power and a concave surface toward the object side; and a sixth lens having a negative refractive power, of which the surface toward the image side is of an aspherical shape which is concave in the vicinity of the optical axis and convex at the peripheral portion thereof. Predetermined conditional formulae are satisfied.

First claim

What is claimed is:

1 . An imaging lens consisting of six lenses, including, in order from the object side to the image side:
a first lens having a positive refractive power and a convex surface toward the object side; a second lens having a negative refractive power; a third lens having a positive refractive power and is of a biconvex shape; a fourth lens having a positive refractive power; a fifth lens having a negative refractive power and a concave surface toward the object side; and a sixth lens having a negative refractive power, of which the surface toward the image side is of an aspherical shape which is concave in the vicinity of the optical axis and convex at the peripheral portion thereof; the conditional formulae below being satisfied:
0.55< f/f 3<1   (1)

0.7< f/f 1<0.95   (3-1)

wherein f is the focal length of the entire lens system, f 1 is the focal length of the first lens, and f 3 is the focal length of the third lens.

2 . An imaging lens as defined in claim 1 , in which the conditional formula below is further satisfied:
1.28< f/f 34<1.62   (7)
wherein f 34 is the combined focal length of the third lens and the fourth lens.

3 . An imaging lens as defined in claim 1 , in which the conditional formula below further is satisfied:
−2.1< f/f 56<−1.1   (2)
wherein f 56 is the combined focal length of the fifth lens and the sixth lens.

4 . An imaging lens as defined in claim 1 , in which the conditional formula below is further satisfied:
0.25< f/f 23456<0.25   (4)
wherein f 23456 is the combined focal length of the second lens through the sixth lens.

5 . An imaging lens as defined in claim 1 , in which the conditional formula below is further satisfied:
0<( R 3 r+R 3 f )/( R 3 r−R 3 f )<0.4   (5)
wherein R3f is the paraxial radius of curvature of the surface of the third lens toward the object side, and R3r is the paraxial radius of curvature of the surface of the third lens toward the image side.

6 . An imaging lens as defined in claim 1 , wherein:
the second lens is a meniscus lens having a convex surface toward the object side.

7 . An imaging lens as defined in claim 1 , wherein:
the fourth lens is a meniscus lens having a concave surface toward the object side.

8 . An imaging lens as defined in claim 1 , in which the conditional formula below is further satisfied:
−3.5<( R 4 r+R 4 f )/( R 4 r−R 4 f )<−1.8   (6)
wherein R4f is the paraxial radius of curvature of the surface of the fourth lens toward the object side, and R4r is the paraxial radius of curvature of the surface of the fourth lens toward the image side.

9 . An imaging lens as defined in claim 1 , in which the conditional formula below is further satisfied:
0.57< f/f 3<0.9   (1-1).

10 . An imaging lens as defined in claim 1 , in which the conditional formula below is further satisfied:
0.58< f/f 3<0.8   (1-2).

11 . An imaging lens as defined in claim 1 , in which the conditional formula below is further satisfied:
−2< f/f 56<−1.2   (2-1)
wherein f 56 is the combined focal length of the fifth lens and the sixth lens.

12 . An imaging lens as defined in claim 1 , in which the conditional formula below is further satisfied:
−1.8< f/f 56<−1.25   (2-2)
wherein f 56 is the combined focal length of the fifth lens and the sixth lens.

13 . An imaging lens as defined in claim 1 , in which the conditional formula below is further satisfied:
0.8< f/f 1<0.9   (3-2).

14 . An imaging lens as defined in claim 1 , in which the conditional formula below is further satisfied:
−0.25< f/f 23456<0   (4-1)
wherein f 23456 is the combined focal length of the second lens through the sixth lens.

15 . An imaging lens as defined in claim 1 , in which the conditional formula below is further satisfied:
0<( R 3 r+R 3 f )/( R 3 r−R 3 f )<0.3   (5-1)
wherein R3f is the paraxial radius of curvature of the surface of the third lens toward the object side, and R3r is the paraxial radius of curvature of the surface of the third lens toward the image side.

16 . An imaging lens as defined in claim 1 , in which the conditional formula below is further satisfied:
−3.4<( R 4 r+R 4 f )/( R 4 r−R 4 f )<−1.9   (6-1)
wherein R4f is the paraxial radius of curvature of the surface of the fourth lens toward the object side, and R4r is the paraxial radius of curvature of the surface of the fourth lens toward the image side.

17 . An imaging apparatus comprising the imaging lens as defined in claim 1 .

18 . An imaging lens consisting of six lenses, including, in order from the object side to the image side:
a first lens having a positive refractive power and a convex surface toward the object side; a second lens having a negative refractive power; a third lens having a positive refractive power and is of a biconvex shape; a fourth lens having a positive refractive power; a fifth lens having a negative refractive power and a concave surface toward the object side; and a sixth lens having a negative refractive power, of which the surface toward the image side is of an aspherical shape which is concave in the vicinity of the optical axis and convex at the peripheral portion thereof; the conditional formula below being satisfied:
1.28< f/f 34<1.62   (7)

wherein f is the focal length of the entire lens system, and f 34 is the combined focal length of the third lens and the fourth lens.

19 . An imaging lens as defined in claim 18 , in which the conditional formula below is further satisfied:
0.6< f/f 1<1   (3)
wherein f 1 is the focal length of the first lens.

20 . An imaging apparatus comprising the imaging lens as defined in claim 18 .

Assignees

• Fujifilm Corp

Inventors

• Noda Takayuki
• Shinohara Yoshikazu
• Ishii Yoshiaki

Classifications

• G02B13/18

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

• G02B5/005

  Diaphragms (for cameras G03B9/02) · CPC title

• G02B27/0025

  for optical correction, e.g. distorsion, aberration · CPC title

• G02B13/0045 Primary

  having five or more lenses · CPC title

• G02B9/62

  having six components only · CPC title