Lens module

1. A lens module comprising:

a first lens having positive refractive power;

a second lens having positive refractive power;

a third lens having refractive power;

a fourth lens having positive refractive power;

a fifth lens having refractive power; and

a sixth lens having negative refractive power and having an inflection point formed on an image-side surface thereof,

wherein the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are disposed in sequential order from the first lens to the sixth lens, and

wherein the lens module satisfies the following Conditional expressions:

0.36< SD/f< 0.48  [Conditional expressions]

V 4− V 5<5.0  [Conditional expressions]

where SD is a size of a stop opening and f is an overall focal length of the lens module,

where V4 is an Abbe number of the fourth lens, and V5 is an Abbe number of the fifth lens.

2. The lens module of claim 1 , wherein the third lens has negative refractive power.

3. The lens module of claim 1 , wherein the fifth lens has negative refractive power.

4. The lens module of claim 1 , wherein an object-side surface of the first lens is convex, and an image-side surface thereof is concave.

5. The lens module of claim 1 , wherein an object-side surface of the second lens is convex, and an image-side surface thereof is convex.

6. The lens module of claim 1 , wherein an object-side surface of the third lens is convex, and an image-side surface thereof is concave.

7. The lens module of claim 1 , wherein an object-side surface of the fourth lens is concave, and an image-side surface thereof is convex.

8. The lens module of claim 1 , wherein an object-side surface of the fifth lens is concave, and an image-side surface thereof is convex.

9. The lens module of claim 1 , wherein an object-side surface of the sixth lens is convex, and the image-side surface thereof is concave.

10. The lens module of claim 1 , wherein the sixth lens has an inflection point formed on an object-side surface thereof.

11. The lens module of claim 1 , wherein the lens module satisfies the following Conditional expressions:

1.1< TTL/f< 1.35  [Conditional expressions]

where TTL is a distance from an object-side surface of the first lens to an image surface of an image sensor, and f is an overall focal length of the lens module.

12. The lens module of claim 1 , wherein the lens module satisfies the following Conditional expressions:

| R 2|−| R 1|>0  [Conditional expressions]

where R1 is a radius of curvature of an object-side surface of the first lens, and R2 is a radius of curvature of an image-side surface of the first lens.

13. The lens module of claim 1 , wherein the lens module satisfies the following Conditional expressions:

SA<36°  [Conditional expressions]

where SA is a sweep angle of the image-side surface of the sixth lens.

14. A lens module comprising:

a first lens having positive refractive power;

a second lens having positive refractive power;

a third lens having refractive power;

a fourth lens having positive refractive power;

a fifth lens having refractive power; and

a sixth lens having negative refractive power,

wherein the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are disposed in sequential order from the first lens to the sixth lens, and

wherein the lens module satisfies the following Conditional expressions:

V 5<30  [Conditional expressions]

V 4− V 5<5.0  [Conditional expressions]

where V4 is an Abbe number of the fourth lens, and V5 is an Abbe number of the fifth lens.

15. The lens module of claim 14 , wherein the third lens has negative refractive power.

16. The lens module of claim 14 , wherein the fifth lens has negative refractive power.

17. The lens module of claim 14 , wherein an object-side surface of the first lens is convex, and an image-side surface thereof is concave.

18. The lens module of claim 14 , wherein an object-side surface of the second lens is convex, and an image-side surface thereof is convex.

19. The lens module of claim 14 , wherein an object-side surface of the third lens is convex, and an image-side surface thereof is concave.

20. The lens module of claim 14 , wherein an object-side surface of the fourth lens is concave, and an image-side surface thereof is convex.

21. The lens module of claim 14 , wherein an object-side surface of the fifth lens is concave, and an image-side surface thereof is convex.

22. The lens module of claim 14 , wherein an object-side surface of the sixth lens is convex, and an image-side surface thereof is concave.

23. The lens module of claim 14 , wherein the sixth lens has an inflection point formed on an object-side surface thereof.

24. The lens module of claim 14 , wherein the lens module satisfies the following Conditional expressions:

1.1< TTL/f< 1.4  [Conditional expressions]

where TTL is a distance from an object-side surface of the first lens to an image surface of an image sensor, and f is an overall focal length of the lens module.

25. The lens module of claim 14 , wherein the lens module satisfies the following Conditional expressions:

| R 2|−| R 1|>0  [Conditional expressions]

where R1 is a radius of curvature of an object-side surface of the first lens, and R2 is a radius of curvature of an image-side surface of the first lens.

26. The lens module of claim 14 , wherein the lens module satisfies the following Conditional expressions:

SA<36°  [Conditional expressions]

where SA is a sweep angle of an image-side surface of the sixth lens.

27. The lens module of claim 14 , wherein the lens module satisfies the following Conditional expressions:

0.36< SD/f< 0.48  [Conditional expressions]

where SD is a size of a stop opening and f is an overall focal length of the lens module.