Imaging lens, camera module, and imaging apparatus

1. An imaging lens comprising: in order from an object side of the imaging lens,

a first lens having a positive power;

a second lens having a negative power, wherein the second lens has a meniscus shape in which a convex surface is directed toward the object side;

a third lens having a positive power and having a convex surface on an image side thereof; and

a fourth lens having a negative power and having a concave surface or a flat surface on the object side at the optical axis of the imaging lens, and

a stop on the optical axis between a vertex of an object side surface of the first lens and a vertex of an image side surface of the first lens,

the imaging lens satisfying conditional expressions (1′) and (6):

0.470≦| f 4/ f| <0.60   (1′)

0.1< D 4/ f< 0.3   (6)

wherein f is a focal length of the imaging lens, f4 is a focal length of the fourth lens, and D4 is a space on the optical axis between the second lens and the third lens.

2. The imaging lens according to claim 1 , further satisfying conditional expressions:

0.5<| f 2/ f|< 3   (3)

0.2< f 3/ f< 1.5   (4)

wherein f2 is a focal length of the second lens, and f3 is a focal lenth of the third lens.

3. The imaging lens according to claim 1 , further satisfying conditional expression:

20< v 1− v 2   (5)

wherein v1 is an Abbe number of the first lens at the d-line, and v2 is an Abbe number of the second lens at the d-line.

4. The imaging lens according to claim 1 , wherein the first lens has a biconvex shape.

5. The imaging lens according to claim 1 , further satisfying conditional expression:

| R 5|> |R 6|  (7)

wherein R5 is a radius of curvature of an object side surface of the third lens, and R6 is a radius of curvature of an image side surface of the third lens.

6. The imaging lens according to claim 1 , wherein each of the first lens, the second lens, the third lens, and the fourth lens includes at least one aspheric surface.

7. The imaging lens according to claim 1 , wherein each of the first lens, the second lens, the third lens, and the fourth lens is made of resin.

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

9. The imaging lens according to claim 1 , wherein the stop is disposed on the optical axis between the vertex of the object side surface of the first lens and an end edge of the object side surface of the first lens.

10. A camera module comprising:

an imaging lens according to claim 1 : and

an imaging device that outputs an imaging signal based on an optical image formed by the imaging lens.

11. An imaging apparatus comprising a camera module according to claim 10 .

12. The imaging lens according to claim 1 , further satisfying conditional expression:

0.50< f 1/ f< 1.10   (2)

wherein f is a focal length of the imaging lens, and f1 is a focal length of the first lens.

13. The imaging lens according to claim 1 , wherein the object side surface of the third lens is formed as a concave surface in the vicinity of the optical axis.

14. The imaging lens according to claim 1 , wherein the image side surface of the fourth lens has a shape which is concave toward the image side in the vicinity of the optical axis and convex toward the image side in the periphery thereof.

15. The imaging lens according to claim 1 , further satisfying conditional expression:

0.30< |f 4/ f|< 0.59   (1A )

wherein f is a focal length of the imaging lens, and f4 is a focal length of the fourth lens.

16. The imaging lens according to claim 1 , further satisfying conditional expression:

0.50< f 1/ f< 1.00   (2A)

wherein f is a focal length of the imaging lens, and f1 is a focal length of the first lens.

17. The imaging lens according to claim 1 , further satisfying conditional expression:

0.7< |f 2/ f|< 2.7   (3A)

wherein f is a local length of the imaging lens, and f2 is a focal length of the second lens.

18. The imaging lens according to claim 1 , further satisfying conditional expression:

0.3< f 3/ f< 1.1   (4A)

wherein f is a focal length of the imaging lens, and f3 is a focal length of the third lens.

19. The imaging lens according to claim 1 , further satisfying conditional expression:

20< v 1− v 2<±  (5A )

wherein v1 is an Abbe number of the first lens at the d-line, and v2 is an Abbe number of the second lens at the d-line.

20. The imaging lens according to claim 1 , further satisfying conditional expression:

0.14 < D 4 /f< 0.25   (6A)

wherein D4 is a space on the optical axis between the second lens and the third lens.

21. An imaging lens comprising: in order from an object side of the imaging, lens,

a first lens having a positive power;

a second lens having a negative power, wherein the second lens has a meniscus shape in which a convex surface is directed toward the object side;

a third lens having a positive power and having a convex surface on an image side thereof: and

a fourth lens having a negative power and having a concave surface or a flat surface on the object side and in a vicinity of an optical axis thereof, and

a stop on the optical axis between a vertex of an object side surface of the first lens and a vertex of an image side surface of the first lens,

the imaging lens satisfying conditional expressions (1) and (6):

0.28< |f 4/ f| <0.60   (1)

0.1< D 4/ f< 0.3   (6)

wherein f is a focal length of the imaging lens, f4 is a focal length of the fourth lens, and D4 is a space on the optical axis between the second lens and the third lens,

wherein the object side surface of the third lens is formed as a convex surface in the vicinity of the optical axis.