Patent ID: 8210230

Claim:
A winding shaft for a roller blind device having a winding tube and having a torsional tensioning device which is coupled with a first end to the winding tube so as to be rotatable with respect to the winding tube, wherein the torsional tensioning device is coupled at least with a second end to the winding tube so as to be rotationally fixed and movable in a longitudinal direction with respect to the winding tube, such that the torsional tensioning device remains undistorted in the axial direction; wherein the rotationally fixed and longitudinally movable coupling takes place by means of a splined shaft profile, and wherein the torsional tensioning device consists of curved spring wire wherein one end of the curved spring wire is slidably disposed within at least one spline groove on an inner side of the winding tube so as to be longitudinally movable and rotationally fixed with respect to the winding tube.