Driving mechanism for optical element

1. An optical element driving mechanism, comprising:

a fixed portion, comprising a base and a case, wherein the case has an opening;

a movable portion that is movable relative to the fixed portion, and is used for connecting to an optical element, wherein the movable portion comprises:

a connecting rod extending along a first direction and passing through the opening, wherein the connecting rod is used for connecting the optical element through the opening of the case;

a first recess extending in the first direction and recessing on a bottom surface of the movable portion, wherein the bottom surface faces the base; and

a plurality of third recesses extending in the first direction and recessing on the bottom surface of the movable portion;

a driving assembly disposed between the fixed portion and the movable portion for driving the movable portion to move relative to the fixed portion; and

a connecting assembly disposed between the fixed portion and the movable portion.

2. The optical element driving mechanism as claimed in claim 1 , wherein a receiving space is formed between the base and the case, and the movable portion and the driving assembly are disposed in the receiving space.

3. The optical element driving mechanism as claimed in claim 1 , wherein the connecting assembly directly connects the base to the movable portion.

4. The optical element driving mechanism as claimed in claim 1 , further comprising a position-sensing element disposed between the movable portion and the base, and the driving assembly surrounds the position-sensing element.

5. The optical element driving mechanism as claimed in claim 1 , wherein a diameter of the opening is greater than a diameter of the connecting rod.

6. The optical element driving mechanism as claimed in claim 1 , wherein the base comprises a recessed portion, and a sidewall of the recessed portion overlaps the movable portion when viewed from the first direction.

7. The optical element driving mechanism as claimed in claim 1 , wherein the base includes a second recess extending in the first direction.

8. The optical element driving mechanism as claimed in claim 7 , wherein the first recess and the second recess at least partially overlap each other when viewed from a second direction that is perpendicular to the first direction.

9. The optical element driving mechanism as claimed in claim 8 , wherein the base further includes two fourth recesses that extend in the first direction, and the third recesses and the fourth recesses at least partially overlap each other when viewed in the second direction that is perpendicular to the first direction.

10. The optical element driving mechanism as claimed in claim 9 , wherein a length of the first recess is greater than a length of any of the third recesses.

11. The optical element driving mechanism as claimed in claim 9 , wherein a length of the second recess is greater than a length of any of the fourth recesses.

12. The optical element driving mechanism as claimed in claim 9 , wherein the first recess extends along an extending line, and the third recesses are symmetrical to the extending line.

13. The optical element driving mechanism as claimed in claim 7 , wherein the connecting assembly is disposed in the first recesses and the second recess concurrently.

14. The optical element driving mechanism as claimed in claim 7 , wherein a length of the first recess is identical to a length of the second recess.

15. The optical element driving mechanism as claimed in claim 1 , wherein the movable portion includes two recesses, and opening directions of the recesses are opposite.

16. The optical element driving mechanism as claimed in claim 1 , wherein the connecting assembly comprises a first connecting element and a second connecting element, wherein both the first connecting element and the second connecting element are spherical, and a diameter of the first connecting element is different than a diameter of the second connecting element.

17. The optical element driving mechanism as claimed in claim 16 , wherein the connecting assembly further comprises another first connecting element, and the second connecting element is disposed between the two first connecting elements.

18. The optical element driving mechanism as claimed in claim 17 , wherein the diameter of the second connecting element is less than the diameter of any of the first connecting elements.