Imaging lens

Patent metadata

Field	Value
Publication number	US-2016306143-A1
Application number	US-201615099152-A
Country	US
Kind code	A1
Filing date	Apr 14, 2016
Priority date	Apr 14, 2015
Publication date	Oct 20, 2016
Grant date	—

Abstract

A compact high-resolution imaging lens which meets the demands for low-profileness, a low F-value and a wide field of view and corrects aberrations properly. It includes, in order from the object side: a first positive lens having a convex object-side surface; a second negative lens having a convex object-side surface; a third lens; a fourth positive lens; and a fifth negative double-sided aspheric lens having a concave image-side surface. When Fno denotes F-number, ih maximum image height, TTL total track length, f45 the composite focal length of the fourth and fifth lenses, r5 and r6 the curvature radii of the third lens object-side and image-side surfaces, r7 and r8 the curvature radii of the fourth lens object-side and image-side surfaces, and r9 and r10 the curvature radii of the fifth lens object-side and image-side surfaces, respectively, it satisfies the following conditions: Fno≦2.4; TTL/2ih<0.9; f45<0; 0<r5/r6<4.0; 0.5<(r7+r8)/(r7−r8)<3.0; and 0.4<(r9+r10)/(r9−r10)<4.0.

First claim

1 . An imaging lens which forms an image of an object on a solid-state image sensor, comprising, in order from an object side to an image side:
a first lens with positive refractive power having a convex surface on the object side; a second lens with negative refractive power having a convex surface on the object side; a third lens with positive or negative refractive power; a fourth lens with positive refractive power; and a fifth lens with negative refractive power as a double-sided aspheric lens having a concave surface on the image side, wherein conditional expressions (1) to (6) below are satisfied:
Fno≦ 2.4  (1)

TTL/ 2 ih< 0.9  (2)

f 45<0  (3)

0< r 5/ r 6<4.0  (4)

0.5<( r 7+ r 8)/( r 7− r 8)<3.0  (5)

0.4<( r 9+ r 10)/( r 9− r 10)<4.0  (6)

where Fno: F-number ih: maximum image height TTL: total track length
f45: composite focal length of the fourth lens and the fifth lens
r5: curvature radius of the object-side surface of the third lens
r6: curvature radius of the image-side surface of the third lens
r7: curvature radius of the object-side surface of the fourth lens
r8: curvature radius of the image-side surface of the fourth lens
r9: curvature radius of the object-side surface of the fifth lens
r10: curvature radius of the image-side surface of the fifth lens.

2 . The imaging lens according to claim 1 ,
wherein a conditional expression (7) below is satisfied:
3.0<| f 3/ f|   (7)

where f: focal length of an overall optical system of the imaging lens
f3: focal length of the third lens.

3 . The imaging lens according to claim 1 ,
wherein a conditional expression (8) below is satisfied:
0.4< f 4/ f< 1.5  (8)

where f: focal length of an overall optical system of the imaging lens
f4: focal length of the fourth lens.

4 . The imaging lens according to claim 1 ,
wherein a conditional expression (9) below is satisfied:
−1.2< f 5/ f<− 0.2  (9)

where f: focal length of an overall optical system of the imaging lens
f5: focal length of the fifth lens.

5 . The imaging lens according to claim 1 ,
wherein a conditional expression (10) below is satisfied:
0.08< T 3/ TTL< 0.16  (10)

where
T3: distance on an optical axis between the image-side surface of the third lens and the object-side surface of the fourth lens.
TTL: total track length.

6 . The imaging lens according to claim 1 ,
wherein a conditional expression (11) below is satisfied:
0.5< f 1/ f< 2.0  (11)

where f: focal length of an overall optical system of the imaging lens
f1: focal length of the first lens.

7 . The imaging lens according to claim 1 ,
wherein a conditional expression (12) below is satisfied:
1.5< r 3/ r 4<50  (12)

where
r3: curvature radius of the object-side surface of the second lens
r4: curvature radius of the image-side surface of the second lens.

8 . The imaging lens according to claim 1 , wherein the fourth lens has a convex surface on the image side.

9 . The imaging lens according to claim 1 , wherein the fifth lens has a pole point off an optical axis on the image-side surface.

10 . The imaging lens according to claim 1 , wherein a conditional expression (13) below is satisfied:
20<ν d 1−ν d 2<40  (13)
where νd1: Abbe number of the first lens at d-ray νd2: Abbe number of the second lens at d-ray.

11 . The imaging lens according to claim 10 , wherein a conditional expression (14) below is satisfied:
50<ν d 3<70  (14)
where νd3: Abbe number of the third lens at d-ray.

12 . The imaging lens according to claim 1 , wherein a conditional expression (15) below is satisfied:
0.70< ih/f< 1.0  (15)
where f: focal length of an overall optical system of the imaging lens
ih: maximum image height.

Assignees

• Kantatsu Co Ltd

Inventors

• Hashimoto Masaya
• Fukaya Hisao

Classifications

• G02B27/0025

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

• G02B13/0045 Primary

  having five or more lenses · CPC title

• G02B9/60 Primary

  having five 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

• G02B13/06

  Panoramic objectives; So-called "sky lenses" {including panoramic objectives having reflecting surfaces} · CPC title