IMAGING LENS

• US 20080180817A1
• Filed: 10/31/2007
• Published: 07/31/2008
• Est. Priority Date: 09/29/2005
• Status: Active Grant

• Current Assignee: Jiangxi Ofilm Optical Company Limited
• Original Assignee: Minoru Taniyama
• Inventors: Taniyama, Minoru
• Granted Patent: US 7,535,658 B2
• Time in Patent Office: Days
• US Class Current: 359/774
• CPC Class Codes: G02B 13/004 having four lenses
• CPC Class Codes: G02B 9/34 having four components only

Abstract

An imaging lens is provided and includes: in order from an object side of the imaging lens, a first lens having a convex surface on the object side and having a positive power; a second lens having a concave surface on the object side and having a negative power; a third lens having a positive power; and a fourth lens having a convex surface on the object side near a paraxial axis and having a meniscus shape. The imaging lens satisfies conditional expressions specified in the specification.

Claims

1. An imaging lens comprising:

in order from an object side of the imaging lens,

a first lens having a convex surface on the object side and having a positive power;

a second lens having a concave surface on the object side and having a negative power;

a third lens having a positive power; and

a fourth lens having a convex surface on the object side near a paraxial axis and having a meniscus shape,

wherein the imaging lens has an air distance between the first lens and the second lens, and the imaging lens satisfies conditional expression (5);

1.9<

f3/f<

20 

 

(5)

wherein f designates a total focal length; and

f3 designates a focal length of the third lens.

2. The imaging lens according to claim 1, further satisfying conditional expression (1):

0.7<

f1/f<

1.1 

 

(1)

wherein f1 designates a focal length of the first lens.

3. The imaging lens according to claim 2, further satisfying conditional expressions (2) and (3):

1.45<

n1<

1.6 

 

(2)

ν

l>

60 (3)

wherein n1 designates a refractive index of the first lens at the d-line; and

ν

1 designates an Abbe number of the first lens at the d-line.

4. The imaging lens according to claim 2, further satisfying conditional expression (4);

0.8<

|f2/f|<

1.8 

 

(4)

wherein f2 designates a focal length of the second lens.

5. The imaging lens according to claim 1, further satisfying conditional expressions (2) and (3):

1.45<

n1<

1.6 

 

(2)

ν

1>

60 

 

(3)

wherein n1 designates a refractive index of the first lens at the d-line; and

ν

1 designates an Abbe number of the first lens at the d-line.

6. The imaging lens according to claim 5, further satisfying conditional expression (4):

0.8<

|f2/f|<

1.8 

 

(4)

wherein f2 designates a focal length of the second lens.

7. The imaging lens according to claim 1, further satisfying conditional expression (4):

0.8<

|f2/f|<

1.8 

 

(4)

wherein f2 designates a focal length of the second lens.

8. The imaging lens according to claim 1, wherein each of the second to fourth lenses includes at least one aspheric surface.

9. The imaging lens according to claim 1, wherein each of the second to fourth lenses is made of a resin material.

10. The imaging lens according to claim 1, wherein the first lens is made of an optical glass.

11. An imaging lens comprising:

in order from an object side of the imaging lens,

a first lens having a convex surface on the object side and having a positive power;

a second lens having a concave surface on the object side and having a negative power;

a third lens having a positive power; and

a fourth lens having a convex surface on the object side near a paraxial axis and having a meniscus shape,

wherein the imaging lens satisfies conditional expressions (1) and (5);

0.7<

f1/f<

1.1 

 

(1)

1.9<

f3/f<

20 

 

(2)

wherein f1 designates a focal length of the first lens;

f designates a total focal length; and

f3 designates a focal length of the third lens.

12. The imaging lens according to claim 11, further satisfying conditional expressions (2) and (3):

1.45<

n1<

1.6 

 

(2)

ν

1>

60 

 

(3)

wherein n1 designates a refractive index of the first lens at the d-line; and

ν

1 designates an Abbe number of the first lens at the d-line.

13. The imaging lens according to claim 11, further satisfying conditional expression (4):

0.8<

|f2/f1|<

1.8 

 

(4)

wherein f2 designates a focal length of the second lens.

14. The imaging lens according to claim 11, wherein each of the second to fourth lenses includes at least one aspheric surface.

15. The imaging lens according to claim 11, wherein each of the second to fourth lenses is made of a resin material.

16. The imaging lens according to claim 11, wherein the first lens is made of an optical glass.