Imaging lens and imaging apparatus equipped with the imaging lens

Patent metadata

Field	Value
Publication number	US-9541732-B2
Application number	US-201514712930-A
Country	US
Kind code	B2
Filing date	May 15, 2015
Priority date	May 23, 2014
Publication date	Jan 10, 2017
Grant date	Jan 10, 2017

Abstract

An imaging lens is constituted by six lenses, including: a first lens having a positive refractive power and a convex surface toward the object side; a second lens having a negative refractive power and a convex surface toward the object side; a third lens having a positive refractive power; a fourth lens having a positive refractive power; a fifth lens having a positive refractive power and a convex surface toward the object side; and a sixth lens having a negative refractive power, provided in this order from the object side. The imaging lens satisfies a predetermined conditional formula.

First claim

What is claimed is:

1. An imaging lens consisting of six lenses, including:
a first lens having a positive refractive power and a convex surface toward the object side;
a second lens having a negative refractive power and a convex surface toward the object side;
a third lens having a positive refractive power;
a fourth lens having a positive refractive power;
a fifth lens having a positive refractive power and a convex surface toward the object side; and
a sixth lens having a negative refractive power, provided in this order from the object side;
the imaging lens satisfying the following conditional formulae:
f 23/ f<− 2.5  (1);

2< f 34/ f< 4.5  (2)

wherein f 23 is the combined focal length of the second lens and the third lens, f 34 is the combined focal length of the third lens and the fourth lens, and f is the focal length of the entire system.

2. An imaging lens as defined in claim 1 , wherein:
the third lens has a convex surface toward the image side.

3. An imaging lens as defined in any claim 1 that further satisfies the conditional formula below:
−7.8< f 56/ f<− 1.2  (3)

wherein f 56 is the combined focal length of the fifth lens and the sixth lens, and f is the focal length of the entire system.

4. An imaging lens as defined in claim 1 that further satisfies the conditional formula below:
−1.75< f 2/ f<− 1.3  (4)

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

5. An imaging lens as defined in claim 1 that further satisfies the conditional formula below:
15< f 4/ f< 120  (6)

wherein f 4 is the focal length of the fourth lens, and f is the focal length of the entire system.

6. An imaging lens as defined in claim 1 that further satisfies the conditional formula below:
−5< f 3/ f 2<−1  (7)

wherein f 3 is the focal length of the third lens, and f 2 is the focal length of the second lens.

7. An imaging lens as defined in claim 1 that further satisfies the conditional formula below:
1< CT 3/ CT 4<6  (9)

wherein CT 3 is the thickness of the third lens along the optical axis, and CT 4 is the thickness of the fourth lens along the optical axis.

8. An imaging lens as defined in claim 1 that further satisfies the conditional formula below:
1.7< CT 5/ CT 6<5  (10)

wherein CT 5 is the thickness of the fifth lens along the optical axis, and CT 6 is the thickness of the sixth lens along the optical axis.

9. An imaging lens as defined in claim 1 that further satisfies the conditional formula below:
2.3<( L 3 r−L 3 f )/( L 3 r+L 3 f )<8.5  (11)

wherein L 3 r is the paraxial radius of curvature of the surface of the third lens toward the image side, and L 3 f is the paraxial radius of curvature of the surface of the third lens toward the object side.

10. An imaging lens as defined in claim 1 that further satisfies the conditional formula below:
−20<( L 6 r−L 6 f )/( L 6 r+L 6 f )<−3.5  (12)

wherein L 6 r is the paraxial radius of curvature of the surface of the sixth lens toward the image side, and L 6 f is the paraxial radius of curvature of the surface of the sixth lens toward the object side.

11. An imaging lens as defined in claim 1 , further comprising:
an aperture stop positioned at the object side of the surface of the second lens toward the object side.

12. An imaging lens as defined in claim 1 that further satisfies the conditional formula below:
0.5< f ·tan ω/ L 6 r< 20  (13)

wherein f is the focal length of the entire system, ω is half the maximum angle of view when focused on an object at infinity, and L 6 r is the paraxial radius of curvature of the surface of the sixth lens toward the image side.

13. An imaging lens as defined in claim 1 that further satisfies the conditional formula below:
f 23/ f<− 2.8  (1-1)

wherein f 23 is the combined focal length of the second lens and the third lens, and f is the focal length of the entire system.

14. An imaging lens as defined in claim 1 that further satisfies the conditional formula below:
2.2< f 34/ f< 4.2  (2-1)

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

15. An imaging lens as defined in claim 1 that further satisfies the conditional formula below:
−6.8< f 56/ f<− 2.2  (3-1)

wherein f 56 is the combined focal length of the fifth lens and the sixth lens, and f is the focal length of the entire system.

16. An imaging apparatus equipped with an imaging lens as defined in claim 1 .

17. An imaging lens consisting of six lenses, including:
a first lens having a positive refractive power and a convex surface toward the object side;
a second lens having a negative refractive power and a convex surface toward the object side;
a third lens having a positive refractive power;
a fourth lens having a positive refractive power;
a fifth lens having a positive refractive power and a convex surface toward the object side; and
a sixth lens having a negative refractive power, provided in this order from the object side;
the imaging lens satisfying the following conditional formulae:
f 23/ f<− 2.5  (1);

2< f 3/ f< 9  (5)

wherein f 23 is the combined focal length of the second lens and the third lens, f 3 is the focal length of the third lens, and f is the focal length of the entire system.

18. An imaging lens consisting of six lenses, including:
a first lens having a positive refractive power and a convex surface toward the object side;
a second lens having a negative refractive power and a convex surface toward the object side;
a third lens having a positive refractive power;
a fourth lens having a positive refractive power;
a fifth lens having a positive refractive power and a convex surface toward the object side; and
a sixth lens having a negative refractive power, provided in this order from the object side;
the imaging lens satisfying the following conditional formulae:
f 23/ f<− 2.5  (1);

1.15< f 1/ f 5<3  (8)

wherein f 23 is the combined focal length of the second lens and the third lens, f is the focal length of the entire system, f 1 is the focal length of the first lens, and f 5 is the focal length of the fifth lens.

Assignees

• Fujifilm Corp

Inventors

• Sun Ping

Classifications

• G02B13/0045

  having five or more lenses · CPC title

• G02B9/62 Primary

  having six components only · 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