Optical connector

1. An optical connector comprising:

a ferrule comprised of a cylindrical body for supporting an optical fiber, and a flange member having an end portion connected to a first end of the cylindrical body, the cylindrical body having a second end formed into a convex surface inclined relative to a plane orthogonal to an axis of the optical fiber, and the flange member having a flange part projecting circumferentially from the end portion thereof;

a holding member supporting the ferrule in an assembled state of the optical connector to define an axis of the optical connector which is collinear with the optical fiber axis in the assembled state of the optical connector, the holding member having an engaging part;

a rotation positioning part formed in the flange part of the flange member for positioning the flange part relative to the holding member to provide a first clearance between the rotation positioning part and the engaging part of the holding member for restricting rotation of the ferrule about the fiber optical axis relative to the holding member; and

a rotation allowing part formed in the flange part of the flange member and spaced from the engaging part of the holding member to provide a second clearance therebetween greater than the first clearance for allowing rotational movement of the ferrule so as to permit the ferrule to incline in a direction transverse to the axis of the optical connector.

2. An optical connector according to claim 1 ; wherein the first clearance between the rotation positioning part and the engaging part of the holding member permits the ferrule to rotate about the optical fiber axis with respect to the holding member within a rotation angle of ±3 degrees or less.

3. An optical connector according to claim 2 ; wherein the rotation positioning part is disposed at an inclination angle of ±5 degrees or greater with respect to the optical fiber axis.

4. An optical connector according to claim 2 ; wherein the flange part of the flange member has a plurality of key grooves forming the rotation positioning part and the rotation allowing part; and wherein the engaging part comprises a plurality of projections projecting into the respective key grooves of the flange part.

5. An optical connector according to claim 1 ; wherein the first clearance between the rotation positioning part and the engaging part of the holding member permits the ferrule to rotate about the optical fiber axis with respect to the holding member within a rotation angle of ±2 degrees or less.

6. An optical connector according to claim 5 ; wherein the rotation positioning part is disposed at an inclination angle of ±5 degrees or greater with respect to the optical fiber axis.

7. An optical connector according to claim 5 ; wherein the flange part of the flange member has a plurality of key grooves forming the rotation positioning part and the rotation allowing part; and wherein the engaging part comprises a plurality of projections projecting into the respective key grooves of the flange part.

8. An optical connector according to claim 1 ; wherein the rotation positioning part is disposed at an inclination angle of ±5 degrees or greater with respect to the optical fiber axis.

9. An optical connector according to claim 8 ; wherein the flange part of the flange member has a plurality of key grooves forming the rotation positioning part and the rotation allowing part; and wherein the engaging part comprises a plurality of projections projecting into the respective key grooves of the flange part.

10. An optical connector according to claim 1 ; wherein the flange part of the flange member has a plurality of key grooves forming the rotation positioning part and the rotation allowing part; and wherein the engaging part comprises a plurality of projections projecting into the respective key grooves of the flange part.

11. An optical connector according to claim 10 ; wherein the cylindrical body of the ferrule has an outer diameter of substantially 2.5 mm.

12. An optical connector according to claim 10 ; wherein each of the key grooves has an axial length of 0.3 mm-0.5 mm.

13. An optical connector according to claim 10 ; wherein the holding member is configured for connection to an SC-type connector adapter.

14. An optical connector according to claim 1 ; wherein the rotation positioning part and the rotation allowing part are formed in an outer peripheral surface of the flange part of the flange member; and wherein the engaging part of the holding member comprises an engaging hole for engagement with the rotation positioning part and the rotation allowing part.

15. An optical connector according to claim 14 ; wherein the rotation allowing part comprises a taper surface of the flange part inclined toward the optical fiber axis.

16. An optical connector according to claim 15 ; wherein the taper surface of the flange part is inclined at an angle of 5 degrees with respect to the optical fiber axis.

17. An optical connector according to claim 15 ; wherein the outer peripheral surface of the flange part is generally disk-shaped.

18. An optical connector according to claim 14 ; wherein the cylindrical body of the ferrule has an outer diameter of substantially 1.25 mm.

19. An optical connector according to claim 18 ; wherein the rotation positioning part has an outer peripheral surface having an axial length of 0.4-0.6 mm.

20. An optical connector according to claim 14 ; wherein the holding member is configured for connection to an MU-type or LC-type connector adapter.

21. An optical connector according to claim 1 ; wherein the flange part of the flange member is generally disk-shaped.

22. An optical connector according to claim 1 ; wherein the flange part of the flange member is in the form of a polygon.

23. An optical connector comprising:

a ferrule having a body for supporting an optical fiber and having a first end formed into a convex surface inclined relative to a plane orthogonal to an axis of the optical fiber, and a flange member having an end portion connected to a second end of the body and a flange part projecting circumferentially from the end portion, the flange part having a plurality of grooves each having a first surface extending along a plane disposed at a first angle relative to the optical fiber axis and a second surface extending along a plane disposed at a second angle relative to the optical fiber axis different from the first angle; and

a holding member supporting the ferrule in an assembled state of the optical connector to define an axis of the optical connector which is collinear with the optical fiber axis in the assembled state of the optical connector, the holding member having a plurality of projecting portions corresponding to respective ones of the grooves of the flange part so that the first surface of each of the grooves is spaced from the corresponding projecting portion to provide a first clearance therebetween for restricting rotation of the ferrule about the fiber optical axis relative to the holding member and so that the second surface of each of the grooves is spaced from the corresponding projecting portion to provide a second clearance therebetween greater than the first clearance for allowing rotational movement of the ferrule so as to permit the ferrule to incline in a direction transverse to the axis of the optical connector.

24. An optical connector according to claim 23 ; wherein the first clearance between the first surface and the corresponding projecting portion permits the ferrule to rotate about the optical fiber axis with respect to the holding member within a rotation angle of ±3 degrees or less.

25. An optical connector according to claim 23 ; wherein the first clearance between the first surface and the corresponding projecting portion permits the ferrule to rotate about the optical fiber axis with respect to the holding member within a rotation angle of ±2 degrees or less.

26. An optical connector according to claim 23 ; wherein the first surface of each of the grooves of the flange part is disposed at an inclination angle of ±5 degrees or greater with respect to the optical fiber axis.

27. An optical connector according to claim 23 ; wherein the body of the ferrule comprises a cylindrical body having an outer diameter of substantially 2.5 mm.

28. An optical connector according to claim 23 ; wherein the body of the ferrule comprises a cylindrical body having an outer diameter of substantially 1.25 mm.

29. An optical connector according to claim 23 ; wherein each of the grooves of the flange part has an axial length of 0.3 mm-0.5 mm.

30. An optical connector according to claim 23 ; herein the second surface of the flange part is inclined toward the optical fiber axis at an angle of about 5 degrees relative to the optical fiber axis.