Optical path folding element, imaging lens module and electronic device

1. An optical path folding element, comprising:

an incident surface allowing a light ray to pass into the optical path folding element;

a path folding surface folding the light ray from the incident surface; and

an exiting surface allowing the light ray to pass through and depart from the optical path folding element;

wherein at least one of the incident surface and the exiting surface comprises:

an optical effective portion; and

at least one engaging structure symmetrically disposed around the optical effective portion and comprising:

an annular surface portion surrounding the optical effective portion; and

an inclined surface portion located between the annular surface portion and the optical effective portion;

wherein an angle between the annular surface portion and the inclined surface portion is θ 1 , and the following condition is satisfied:

95 degrees<θ1<130 degrees.

2. The optical path folding element of claim 1 , wherein the optical path folding element is made of a plastic material.

3. The optical path folding element of claim 2 , wherein the path folding surface comprises an aluminum metallic layer covered thereon.

4. The optical path folding element of claim 2 , wherein the angle between the annular surface portion and the inclined surface portion is θ 1 , and the following condition is satisfied:

100 degrees<θ1<120 degrees.

5. The optical path folding element of claim 2 , wherein an Abbe number of the optical path folding element is V, and the following condition is satisfied:

V<32.0.

6. The optical path folding element of claim 2 , wherein a width of the inclined surface portion is L 1 , and the following condition is satisfied:

0.07 mm<L1<0.35 mm.

7. The optical path folding element of claim 2 , wherein the light ray is folded by 90 degrees when passing through the path folding surface.

8. The optical path folding element of claim 2 , wherein a distance between a center of the incident surface and a center of the path folding surface is equal to a distance between the center of the path folding surface and a center of the exiting surface.

9. The optical path folding element of claim 2 , wherein an area occupied by the optical effective portion is equal to or more than 40% of a total area of the incident surface or the exiting surface.

10. An imaging lens module, comprising:

the optical path folding element of claim 1 .

11. The imaging lens module of claim 10 , wherein the imaging lens module comprises at least one lens element, and the lens element is engaged with the engaging structure.

12. The imaging lens module of claim 10 , wherein the imaging lens module comprises at least one opaque member, and the opaque member is engaged with the engaging structure.

13. An electronic device, comprising:

the imaging lens module of claim 10 .

14. An optical path folding element, comprising:

an incident surface allowing a light ray to pass into the optical path folding element;

a path folding surface folding the light ray from the incident surface; and

an exiting surface allowing the light ray to pass through and depart from the optical path folding element;

wherein at least one of the incident surface and the exiting surface comprises:

an optical effective portion; and

at least one engaging structure symmetrically disposed around the optical effective portion and comprising:

an annular surface portion surrounding the optical effective portion; and

a conical surface located between the annular surface portion and the optical effective portion;

wherein an angle between the annular surface portion and the conical surface is θ 2 , and the following condition is satisfied:

95 degrees<θ2<130 degrees.

15. The optical path folding element of claim 14 , wherein the optical path folding element is made of plastic material.

16. The optical path folding element of claim 14 , wherein the angle between the annular surface portion and the conical surface is θ 2 , and the following condition is satisfied:

100 degrees<θ2<120 degrees.

17. The optical path folding element of claim 14 , wherein the conical surface is a closed ring.

18. The optical path folding element of claim 14 , wherein a width of the conical surface is L 2 , and the following condition is satisfied:

0.07 mm<L2<0.35 mm.

19. The optical path folding element of claim 14 , wherein an Abbe number of the optical path folding element is V, and the following condition is satisfied:

V<32.0.

20. The optical path folding element of claim 14 , wherein an Abbe number of the optical path folding element is V, and the following condition is satisfied:

V<25.0.

21. The optical path folding element of claim 14 , wherein the light ray is folded by 90 degrees when passing through the path folding surface.

22. The optical path folding element of claim 14 , wherein a distance between a center of the incident surface and a center of the path folding surface is equal to a distance between the center of the path folding surface and a center of the exiting surface.

23. An imaging lens module, comprising:

the optical path folding element of claim 14 .

24. An electronic device, comprising:

the imaging lens module of claim 23 .