Imaging lens, and electronic apparatus including the same

1. An imaging lens comprising a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element and a sixth lens element arranged in order from an object side to an image side along an optical axis of said imaging lens, each of said first lens element, said second lens element, said third lens element, said fourth lens element, said fifth lens element and said sixth lens element having a refractive power, an object-side surface facing toward the object side, and an image-side surface facing toward the image side, wherein:

said first lens element has a positive refractive power;

said second lens element has a negative refractive power, said object-side surface of said second lens element has a convex portion in a vicinity of the optical axis and an outermost portion of said object-side surface of said second lens element for passage of imaging light is a concave portion, and an outermost portion of said image-side surface of said second lens element for passage of imaging light is a concave portion;

said image-side surface of said third lens element has a convex portion in a vicinity of the optical axis;

said fourth lens element has a negative refractive power, said object-side surface of said fourth lens element has a concave portion in a vicinity of the optical axis;

an outermost portion of said image-side surface of said fifth lens element for passage of imaging light is a convex portion;

said image-side surface of said sixth lens element has a concave portion in a vicinity of the optical axis and an outermost portion of said image-side surface of said sixth lens element for passage of imaging light is a convex portion; and

said imaging lens does not include any lens element with a refractive power other than said first lens element, said second lens element, said third lens element, said fourth lens element, said fifth lens element and said sixth lens element, satisfying (G 23 +G 56 )/(G 12 +G 45 )≦3.80 and 9≧EFL/T 3 ≧5.50, where G 12 represents an air gap length between said first lens element and said second lens element at the optical axis, G 23 represents an air gap length between said second lens element and said third lens element at the optical axis, G 45 represents an air gap length between said fourth lens element and said fifth lens element at the optical axis, G 56 represents an air gap length between said fifth lens element and said sixth lens element at the optical axis, EFL represents a system focal length of said imaging lens, and T 3 represents a thickness of said third lens element at the optical axis.

2. The imaging lens as claimed in claim 1 , satisfying Gaa/T 6 ≦3.75, where Gaa represents a sum of five air gap lengths among said first lens element, said second lens element, said third lens element, said fourth lens element, said fifth lens element and said sixth lens element at the optical axis, and T 6 represents a thickness of said sixth lens element at the optical axis.

3. The imaging lens as claimed in claim 2 , further satisfying T 1 /(G 12 +G 45 )≦2.40, where T 1 represents a thickness of said first lens element at the optical axis.

4. The imaging lens as claimed in claim 3 , further satisfying 2.6≧BFL/(G 12 +G 23 )≧1.90, where BFL represents a distance at the optical axis between said image-side surface of said sixth lens element and an image plane at the image side.

5. The imaging lens as claimed in claim 2 , further satisfying 1.6≧T 6 /T 1 ≧1.00, where T 1 represents a thickness of said first lens element at the optical axis.

6. The imaging lens as claimed in claim 5 , further satisfying 15≧EFL/T 5 ≧6.40, where T 5 represents a thickness of said fifth lens element at the optical axis.

7. The imaging lens as claimed in claim 2 , further satisfying T 3 /G 45 ≦15.00.

8. The imaging lens as claimed in claim 7 , further satisfying 2.9≧BFL/T 1 ≧2.20, where BFL represents a distance at the optical axis between said image-side surface of said sixth lens element and an image plane at the image side, and T 1 represents a thickness of said first lens element at the optical axis.

9. The imaging lens as claimed in claim 1 , further satisfying 2.5≧BFL/T 3 ≧1.70, where BFL represents a distance at the optical axis between said image-side surface of said sixth lens element and an image plane at the image side.

10. The imaging lens as claimed in claim 1 , satisfying (G 34 +G 56 )/G 45 ≦21.50, where G 34 represents an air gap length between said third lens element and said fourth lens element at the optical axis.

11. The imaging lens as claimed in claim 10 , further satisfying (G 23 +G 56 )/T 6 ≦2.10, where T 6 represents a thickness of said sixth lens element at the optical axis.

12. The imaging lens as claimed in claim 11 , further satisfying 2.9≧BFL/T 1 ≧2.20, where BFL represents a distance at the optical axis between said image-side surface of said sixth lens element and an image plane at the image side, and T 1 represents a thickness of said first lens element at the optical axis.

13. The imaging lens as claimed in claim 11 , further satisfying 4≧BFL/T 5 ≧1.75, where BFL represents a distance at the optical axis between said image-side surface of said sixth lens element and an image plane at the image side, and T 5 represents a thickness of said fifth lens element at the optical axis.

14. The imaging lens as claimed in claim 13 , further satisfying 0.5≦T 1 /(G 12 +G 45 )≦2.40, where T 1 represents a thickness of said first lens element at the optical axis.

15. The imaging lens as claimed in claim 10 , further satisfying ALT/T 6 ≦7.20, where ALT represents a sum of thicknesses of said first lens element, said second lens element, said third lens element, said fourth lens element, said fifth lens element and said sixth lens element at the optical axis, and T 6 represents the thickness of said sixth lens element at the optical axis.

16. The imaging lens as claimed in claim 15 , further satisfying 4≧BFL/T 5 ≧1.75 and 1.6≧T 6 /T 1 ≧1.00, where BFL represents a distance at the optical axis between said image-side surface of said sixth lens element and an image plane at the image side, T 1 represents the thickness of said first lens element at the optical axis, and T 5 represents the thickness of said fifth lens element at the optical axis.

17. An electronic apparatus comprising:

a housing; and

an imaging module disposed in said housing, and including an imaging lens as claimed in claim 1 , a barrel on which said imaging lens is disposed, a holder unit on which said barrel is disposed, and an image sensor disposed at the image side of said imaging lens.