Mobile device and optical imaging lens thereof

1. An optical 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, each of the lens elements comprising refractive power;

wherein the lens elements are arranged sequentially from an object side to an image side along an optical axis;

wherein each of the lens elements comprises an object-side surface facing toward the object side and an image-side surface facing toward the image side;

wherein the object-side surface of the first lens element comprises a convex surface;

wherein the object-side surface of the second lens element comprises a convex portion in a vicinity of the optical axis and a convex portion in a vicinity of a periphery of the second lens element;

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

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

wherein the refracting power of the fourth lens element is positive, and the image-side surface of the fourth lens element comprises a convex portion in a vicinity of the optical axis; and

wherein the image-side surface of the sixth lens element comprises a concave portion in a vicinity of the optical axis and a convex portion in a vicinity of a periphery of the sixth lens element;

wherein an air gap between the third lens element and the fourth lens element along the optical axis is represented by AG34, a sum of all five air gaps from the first lens element to the sixth lens element along the optical axis is represented by AAG, and AG34 and AAG satisfy the equation:

AAG/AG 34≤3.5;

a central thickness of the second lens element along the optical axis is represented by T2, an air gap between the fifth lens element and the sixth lens element along the optical axis is represented by AG56, and T2 and AG56 satisfy the equation:

2.0≤ T 2/ AG 56≤9.5;

the optical imaging lens as a whole comprises only the six lens elements each comprising refracting power.

2. The optical imaging lens according to claim 1 , wherein a central thickness of the fifth lens element along the optical axis is represented by T5, an air gap between the first lens element and the second lens element along the optical axis is represented by AG12, and T5 and AG12 satisfy the equation:

T 5/ AG 12≤5.5.

3. The optical imaging lens according to claim 2 , wherein a central thickness of the sixth lens element along the optical axis is represented by T6, a sum of the thickness of all six lens elements along the optical axis is represented by ALT, and T6 and ALT satisfy the equation:

5.0≤ ALT/T 6≤10.0.

4. The optical imaging lens according to claim 3 , wherein a central thickness of the third lens element along the optical axis is represented by T3, and T3 and AG12 satisfy the equation:

T 3/ AG 12≤2.6.

5. The optical imaging lens according to claim 2 , wherein AG12 and AAG satisfy the equation:

AAG/AG 12≤11.0.

6. The optical imaging lens according to claim 5 , wherein a central thickness of the first lens element along the optical axis is represented by T1, a central thickness of the sixth lens element along the optical axis is represented by T6, and T1 and T6 satisfy the equation:

0.85≤ T 1/ T 6≤1.5.

7. The optical imaging lens according to claim 6 , wherein T2 and T5 satisfy the equation:

1.0≤ T 2/ T 5≤3.0.

8. The optical imaging lens according to claim 1 , wherein an air gap between the first lens element and the second lens element along the optical axis is represented by AG12, and AG12 and AAG satisfy the equation:

AAG/AG 12≤11.0.

9. The optical imaging lens according to claim 8 , wherein a central thickness of the sixth lens element along the optical axis is represented by T6, a sum of the thickness of all six lens elements along the optical axis is represented by ALT, and T6 and ALT satisfy the equation:

5.0≤ ALT/T 6≤10.0.

10. The optical imaging lens according to claim 9 , wherein a central thickness of the third lens element along the optical axis is represented by T3, and T3 and AAG satisfy the equation:

3.0≤ AAG/T 3≤6.0.

11. The optical imaging lens according to claim 1 , wherein a central thickness of the sixth lens element along the optical axis is represented by T6, a sum of the thickness of all six lens elements along the optical axis is represented by ALT, and T6 and ALT satisfy the equation:

5.0≤ ALT/T 6≤10.0.

12. The optical imaging lens according to claim 11 , wherein an air gap between the first lens element and the second lens element along the optical axis is represented by AG12, an air gap between the second lens element and the third lens element along the optical axis is represented by AG23, an air gap between the fourth lens element and the fifth lens element along the optical axis is represented by AG45, and AG12, AG23 and AG45 satisfy the equation:

( AG 23+ AG 45)/ AG 12≤4.5.

13. The optical imaging lens according to claim 12 , wherein a central thickness of the fifth lens element along the optical axis is represented by T5, and T5 and AG34 satisfy the equation:

T 5/ AG 34≤2.5.

14. The optical imaging lens according to claim 12 , wherein a central thickness of the fifth lens element along the optical axis is represented by T5, and T5 and AAG satisfy the equation:

2.2≤ AAG/T 5≤5.0.

15. The optical imaging lens according to claim 11 , wherein an air gap between the first lens element and the second lens element along the optical axis is represented by AG12, and T6 and AG12 satisfy the equation:

T 6/ AG 12≤5.0.

16. The optical imaging lens according to claim 1 , wherein the object-side surface of the sixth lens element comprises a convex portion in a vicinity of a periphery of the sixth lens element.

17. A mobile device, comprising:

a housing; and

a photography module positioned in the housing and comprising:

the optical imaging lens as claimed in claim 1 ;

a lens barrel for positioning the optical imaging lens;

a module housing unit for positioning the lens barrel; and

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