Lens module

1. A lens module comprising:

a first lens, an object-side surface thereof being concave;

a second lens, an object-side surface thereof being convex, and an image-side surface thereof being convex;

a third lens, an object-side surface thereof being concave;

a fourth lens having refractive power;

a fifth lens having refractive power, an object-side surface thereof being concave; and

a sixth lens having one or more inflection points on an image-side surface thereof;

wherein the first to sixth lenses are sequentially disposed in numerical order from the first lens to the sixth lens starting at an object side of the lens module.

2. The lens module of claim 1 , wherein an image-side surface of the first lens is convex.

3. The lens module of claim 1 , wherein an image-side surface of the third lens is convex.

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

5. The lens module of claim 1 , wherein an image-side surface of the fifth lens is convex.

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

7. A lens module comprising:

a first lens having negative refractive power;

a second lens, an object-side surface thereof being convex, and an image-side surface thereof being convex;

a third lens, an object-side surface thereof being concave, and an image-side surface thereof being convex; concave;

a fourth lens having refractive power;

a fifth lens, an image-side surface thereof being concave; and

a sixth lens having one or more inflection points on an image-side surface thereof;

wherein the first to sixth lenses are sequentially disposed in numerical order from the first lens to the sixth lens starting at an object side of the lens module; and

TTL/D 23 <11.0 is satisfied,

where TTL is a distance from an object-side surface of the first lens to an image plane of the lens module, and

D 23 is a distance from the image-side surface of the second lens to the object-side surface of the third lens.

8. The lens module of claim 7 , wherein the third lens has positive refractive power or the fourth lens has negative refractive power.

9. The lens module of claim 7 , wherein the fifth lens has positive refractive power or the sixth lens has negative refractive power.

10. The lens module of claim 7 , wherein 0.7<f 12 /f<0.9 is satisfied,

where f 12 is a composite focal length of the first and second lenses, and

f is an overall focal length of an optical system comprising the first to sixth lenses.

11. The lens module of claim 7 , wherein BFL/f<0.3 is satisfied,

where BFL is a distance from the image-side surface of the sixth lens to the image plane, and

f is an overall focal length of an optical system comprising the first to sixth lenses.

12. The lens module of claim 7 , wherein 0.4<r 3 /f is satisfied,

where r 3 is a radius of curvature of the object-side surface of the second lens, and

f is an overall focal length of an optical system comprising the first to sixth lenses.

13. The lens module of claim 7 , wherein 30<|V 1 −V 2 |<40 is satisfied,

where V 1 is an Abbe number of the first lens, and

V 2 is an Abbe number of the second lens.

14. The lens module of claim 7 , wherein −0.1<(r 9 −r 10 )/(r 9 +r 10 ) is satisfied,

where r 9 is a radius of curvature of an object-side surface of the fifth lens, and

r 10 is a radius of curvature of the image-side surface of the fifth lens.

15. The lens module of claim 7 , wherein −0.4<(r 1 −r 2 )/(r 1 +r 2 )<0.6 is satisfied,

where r 1 is a radius of curvature of the object-side surface of the first lens, and

r 2 is a radius of curvature of an image-side surface of the first lens.

16. The lens module of claim 7 , wherein SL/TTL<0.85 is satisfied,

where SL is a distance from a stop to the image plane, and

TTL is a distance from the object-side surface of the first lens to the image plane.

17. The lens module of claim 16 , wherein the stop is disposed between the first lens and the second lens.