Mobile device and optical imaging lens thereof

1. An optical imaging lens, sequentially from an object side to an image side along an optical axis, comprising an aperture stop, and first, second, third, fourth and fifth lens elements, each of said first, second, third, fourth and fifth lens elements having refracting index, an object-side surface facing toward the object side and an image-side surface facing toward the image side and a central thickness defined along the optical axis, wherein:

said image-side surface of said first lens element comprises a convex portion in a vicinity of a periphery of the first lens element;

said image-side surface of said second lens element comprises a concave portion in a vicinity of a periphery of the second lens element;

said object-side surface of said third lens element comprises a concave portion in a vicinity of a periphery of the third lens element;

said object-side surface of said fourth lens element comprises a convex portion in a vicinity of the optical axis, and said image-side surface of said fourth lens element comprises a concave portion in a vicinity of the optical axis;

said object-side surface of said fifth lens element comprises a concave portion in a vicinity of the optical axis;

the optical imaging lens comprises no other lenses having refracting index beyond the five lens elements; and

an air gap between the fourth lens element and the fifth lens element along the optical axis is represented by G45, a sum of central thicknesses of all five lens elements is represented by ALT, and G45 and ALT satisfy the inequality:

10.667 ≧ALT/G 45≧5.6; and

an air gap between the second lens element and the third lens element along the optical axis is G23, and G23 and ALT satisfy the inequality:

5.53 ≧ALT/G 23≧3.2.

2. The optical imaging lens according to claim 1 , wherein a central thickness of the second lens element is represented by CT2, a central thickness of the fourth lens element is represented by CT4, and CT2 and CT4 satisfy the inequality:

0.84≧CT2/CT4≧0.42.

3. The optical imaging lens according to claim 2 , wherein a central thickness of the third lens element is represented by CT3, an air gap between the second lens element and the third lens element along the optical axis is represented by G23, and CT3 and G23 satisfy the inequality:

1.66≧CT3 /G 23≧0.5.

4. The optical imaging lens according to claim 1 , wherein a central thickness of the third lens element is represented by CT3, a central thickness of the fifth lens element is represented by CT5, and CT3 and CT5 satisfy the inequality:

2.14≧CT3/CT5≧0.75.

5. The optical imaging lens according to claim 4 , wherein a central thickness of the first lens element is represented by CT1, a central thickness of the fourth lens element is represented by CT4, and CT1 and CT4 satisfy the inequality:

1.88≧CT1/CT4≧1.2.

6. The optical imaging lens according to claim 1 , wherein a central thickness of the fourth lens element is represented by CT4, and CT4 and ALT satisfy the inequality:

6.72 ≧ALT /CT4≧3.8.

7. The optical imaging lens according to claim 6 , wherein a central thickness of the first lens element is represented by CT1, a central thickness of the third lens element is represented by CT3, and CT1 and CT3 satisfy the inequality:

1.04≧CT3/CT1≧0.65.

8. The optical imaging lens according to claim 1 , wherein a sum of all four air gaps from the first lens element to the fifth lens element along the optical axis is represented by Gaa, and G45 and Gaa satisfy the inequality:

4.72 ≧Gaa/G 45≧3.7.

9. The optical imaging lens according to claim 8 , wherein a central thickness of the first lens element is represented by CT1, a central thickness of the third lens element is represented by CT3, and CT1 and CT3 satisfy the inequality:

1.04≧CT3/CT1≧0.53.

10. The optical imaging lens according to claim 1 , wherein a central thickness of the first lens element is represented by CT1, an air gap between the second lens element and the third lens element along the optical axis is represented by G23, and CT1 and G23 satisfy the inequality:

1.61≧CT1 /G 23≧0.8.

11. The optical imaging lens according to claim 10 , wherein a central thickness of the third lens element is represented by CT3, a central thickness of the fourth lens element is represented by CT4, and CT3 and CT4 satisfy the inequality:

1.82≧CT3/CT4≧0.6.

12. The optical imaging lens according to claim 1 , wherein a central thickness of the first lens element is represented by CT1, and CT1 and G45 satisfy the inequality:

3.1≧CT1 /G 45≧1.65.

13. The optical imaging lens according to claim 12 , wherein a central thickness of the second lens element is represented by CT2, and CT2 and ALT satisfy the inequality:

11.33 ≧ALT /CT2≧9.5.

14. The optical imaging lens according to claim 1 , wherein a central thickness of the second lens element is represented by CT2, a central thickness of the third lens element is represented by CT3, and CT2 and CT3 satisfy the inequality:

3.4≧CT3/CT2≧1.4.

15. The optical imaging lens according to claim 1 , wherein a sum of all four air gaps from the first lens element to the fifth lens element along the optical axis is represented by Gaa, and Gaa and ALT satisfy the inequality:

2.87 ≧ALT/Gaa≧ 1.75.

16. The optical imaging lens according to claim 15 , wherein a central thickness of the third lens element is represented by CT3, an air gap between the second lens element and the third lens element along the optical axis is G23, and CT3 and G23 satisfy the inequality:

1.66≧CT3 /G 23≧0.8.

17. A mobile device, comprising:

a housing; and

a photography module positioned in the housing and comprising:

an optical imaging lens, sequentially from an object side to an image side along an optical axis, comprising an aperture stop, first, second, third, fourth and fifth lens elements, each of said first, second, third, fourth and fifth lens elements having refracting index, an object-side surface facing toward the object side and an image-side surface facing toward the image side and a central thickness defined along the optical axis, wherein:

said image-side surface of said first lens element comprises a convex portion in a vicinity of a periphery of the first lens element;

said image-side surface of said second lens element comprises a concave portion in a vicinity of a periphery of the second lens element;

said object-side surface of said third lens element comprises a concave portion in a vicinity of a periphery of the third lens element;

said object-side surface of said fourth lens element comprises a convex portion in a vicinity of the optical axis, and said image-side surface of said fourth lens element comprises a concave portion in a vicinity of the optical axis;

said object-side surface of said fifth lens element comprises a concave portion in a vicinity of the optical axis;

the optical imaging lens comprises no other lenses having refracting index beyond the five lens elements; and

an air gap between the fourth lens element and the fifth lens element along the optical axis is represented by G45, a sum of the central thicknesses of all five lens elements is represented by ALT, and G45 and ALT satisfy the inequality:

10.667 ≧ALT/G 45≧5.6; and

an air gap between the second lens element and the third lens element along the optical axis is G23, and G23 and ALT satisfy the inequality:

5.53 ≧ALT/G 23≧3.2;

a lens barrel for positioning the optical imaging lens;

a module housing unit for positioning the lens barrel;

a substrate for positioning the module housing unit; and

an image sensor positioned at the image side of the optical imaging lens.