IMAGING LENS, AND IMAGING DEVICE AND MOBILE TERMINAL APPARATUS USING THE SAME

• US 20100014175A1
• Filed: 12/21/2007
• Published: 01/21/2010
• Est. Priority Date: 12/22/2006
• Status: Active Grant

• Current Assignee: Seiko Precision Incorporated (Seiko Group Corp.)
• Original Assignee: Seiko Precision Incorporated (Seiko Group Corp.)
• Inventors: Nio, Junichi
• Granted Patent: US 7,880,980 B2
• Time in Patent Office: Days
• US Class Current: 359/773
• CPC Class Codes: G02B 13/004 having four lenses
• CPC Class Codes: G02B 9/34 having four components only

Abstract

A first lens (L1), a second lens (L2), a third lens (L3), and a fourth lens (L4) are arranged in this order from an object side. The first lens (L1) has a biconvex shape and a positive refracting power. The second lens (L2) has a meniscus shape that is convex toward the object side, and has a negative refracting power. The third lens (L3) has a meniscus shape that is convex toward an image side, and has a positive refracting power. The fourth lens (L4) has a meniscus shape that is convex toward the object side, and has a negative refracting power. A chromatic aberration generated by the first lens (L1) is corrected by the second lens (L2). A chromatic aberration generated by the third lens (L3) is corrected by the fourth lens (L4).

Claims

1. An imaging lens, comprising a first lens, a second lens, a third lens, and a fourth lens that are arranged in this order from an object side,

wherein the first lens has a biconvex shape and a positive refracting power,

the second lens has a meniscus shape that is convex toward the object side, and has a negative refracting power,

the third lens has a meniscus shape that is convex toward an image side, and has a positive refracting power, and

the fourth lens has a meniscus shape that is convex toward the object side, and has a negative refracting power.

2. The imaging lens according to claim 1, which satisfies the following conditional expressions (1) to (5), which are

1.3<

f/f1<

1.8 

 

(1),

1.1<

f/f3<

2.15 

 

(2),

−

0.006<

1/f1ν

1+1/f2ν

2<

0 

 

(3),

0<

1/f3ν

3+1/f4ν

4<

0.002 

 

(4), and

0.15<

T23/TTL<

0.25 

 

(5),

where

f;

integral focal length of an entire lens system,

f1;

focal length of the first lens,

f2;

focal length of the second lens,

f3;

focal length of the third lens,

f4;

focal length of the fourth lens,

ν

1;

Abbe number of a d-line of the first lens,

ν

2;

Abbe number of a d-line of the second lens,

ν

3;

Abbe number of a d-line of the third lens,

ν

4;

Abbe number of a d-line of the fourth lens,

T23;

air distance between the second lens and the third lens, and

TTL;

distance between an apex of the first lens and an image formation plane.

3. The imaging lens according to claim 1, comprising an aperture stop that is arranged closer to the object side than the first lens is.

4. The imaging lens according to claim 1, comprising an aperture stop that is arranged between the first lens and the second lens.

5. The imaging lens according to claim 1,

wherein an integral focal length f of the first lens to the fourth lens satisfies a condition of 4.426 mm≦

f≦

4.896 mm.

6. The imaging lens according to claim 1,

wherein an integral F-number of the first lens to the fourth lens satisfies a condition of 2.8≦

F≦

3.0.

7. The imaging lens according to claim 1,

wherein an integral field angle 2ω

of the first lens to the fourth lens satisfies a condition of 58.9°

≦

2ω

≦

67.9°

.

8. The imaging lens according to claim 1, comprising a parallel-plate glass that is arranged between the fourth lens and the image formation plane.

9. An imaging device, comprising:

the imaging lens according to claim 1; and

an imaging element that converts an object image formed by the imaging lens into an electric signal.

10. A mobile terminal apparatus, comprising the imaging device according to claim 9.