Differential signal transmission cable

1. A differential signal transmission cable comprising:

a pair of conductors arranged to be distant from each other and parallel to each other;

an insulator covering the pair of conductors, the insulator having an outer periphery shape of a transversal cross section in that a plurality of curved lines with different curvature radiuses are combined; and

a shield conductor wound around the insulator, the shield conductor having an inner periphery shape of a transversal cross section in that the plurality of curved lines are combined in accordance with the outer periphery shape of the insulator,

wherein the shield conductor comprises a seam or an overlapping region along a longitudinal direction of the insulator.

2. The differential signal transmission cable according to claim 1 , wherein a minimum value of the curvature radiuses of the plurality of curved lines is 1/20 or more and ¼ or less of a maximum value of the curvature radiuses of the plurality of curved lines.

3. The differential signal transmission cable according to claim 2 , wherein the outer periphery shape of the transversal cross section of the insulator comprises an elliptical shape, and a minor axis of the transversal cross section is preferably 0.37 times or more and 0.63 times or less of a major axis of the transversal cross section.

4. The differential signal transmission cable according to claim 1 , further comprising:

a jacket member coating the shield conductor,

wherein the shield conductor comprises an insulating member and an electrically conductive film provided on the insulating member at a surface facing to the jacket member.

5. The differential signal transmission cable according to claim 4 , wherein the shield conductor comprises a seam or an overlapping region along a longitudinal direction of the insulator, and the jacket member comprises a seam or an overlapping region spirally on the shield conductor.

6. The differential signal transmission cable according to claim 4 , wherein the shield conductor comprises a seam or an overlapping region on the insulator, and the jacket member comprises a braid.

7. The differential signal transmission cable according to claim 1 , wherein the insulator comprises a foam material.

8. The differential signal transmission cable according to claim 7 , wherein the insulator comprises an outer layer having a foaming degree smaller than a foaming degree of a portion interior to the outer layer.

9. The differential signal transmission cable according to claim 1 , wherein the shield conductor continuously contacts an outer periphery of the insulator at the transversal cross section thereof.

10. The differential signal transmission cable according to claim 1 , wherein the shield conductor is disposed on the insulator such that air gaps between the shield conductor and insulator are absent.

11. A differential signal transmission cable comprising:

a pair of conductors arranged to be distant from each other and parallel to each other;

an insulator covering the pair of conductors, the insulator having an outer periphery shape of a transversal cross section in that a plurality of curved lines with different curvature radiuses are combined; and

a shield conductor wound around the insulator, the shield conductor having an inner periphery shape of a transversal cross section in that the plurality of curved lines are combined in accordance with the outer periphery shape of the insulator,

wherein a drain wire is absent from the differential signal transmission cable.

12. The differential signal transmission cable according to claim 11 , wherein the insulator is continuous within the outer periphery shape thereof except for the pair of conductors.

13. The differential signal transmission cable according to claim 11 , wherein the shield conductor comprises a seam or an overlapping region along a longitudinal direction of the insulator.

14. The differential signal transmission cable according to claim 11 , further comprising:

a jacket member coating the shield conductor,

wherein a drain wire is absent within the jacket member.

15. The differential signal transmission cable according to claim 11 , wherein the shield conductor continuously contacts an outer periphery of the insulator at the transversal cross section thereof.

16. A differential signal transmission cable comprising:

a pair of conductors arranged to be distant from each other and parallel to each other;

an insulator covering the pair of conductors, the insulator having an outer periphery shape of a transversal cross section in that a plurality of curved lines with different curvature radiuses are combined; and

a shield conductor wound around the insulator, the shield conductor having an inner periphery shape of a transversal cross section in that the plurality of curved lines are combined in accordance with the outer periphery shape of the insulator,

wherein a distance between the pair of conductors is less than distances from the pair of conductors to the shield conductor.

17. The differential signal transmission cable according to claim 16 , wherein the distances from the pair of conductors to the shield conductor are measured along a plane passing through the pair of conductors.

18. The differential signal transmission cable according to claim 16 , wherein the pair of conductors and the shield conductor are configured so as to allow differential signals of 10 Gbs.

19. The differential signal transmission cable according to claim 16 , wherein the shield conductor continuously contacts an outer periphery of the insulator at the transversal cross section.

20. The differential signal transmission cable according to claim 16 , wherein the shield conductor is under tension so as to apply a normal force around an entire circumference thereof.