Patent ID: 8033193

Claim:
An actuating system for a roller blind, the actuating system comprising: a first shaft; and a device for limiting a number of rotations of the first shaft to control a first and a second end-of-travel position of the roller blind, the device comprising a second shaft rotating together with the first shaft, two elongated elements, each elongated element being substantially parallel to the second shaft, one of the elongated elements having a thread that comprises a different thread direction than a thread of the other elongated element, two female-threaded elements, each female-threaded element being mounted respectively on the threads of the respective elongated element, each female-threaded element being engaged with the second shaft and, when rotating with the second shaft, being free to move along the respective thread of one of the elongated element in an opposite direction to the other female-thread element into one of the end-of-travel positions; a support for supporting said second shaft and said elongated elements; a means for stopping a revolution of said first shaft, the means being provided on said support and actuated by said female-thread elements when they reach one of the end-of-travel position on said elongated elements; wherein said female-thread elements or said elongated elements being adapted to undergo momentary deformation upon reaching one of the end-of-travel position with an effect of being disengaged from the thread of the other element; wherein said deformation is obtained by means of at least one groove formed in either each of the elongated elements or each of the female-thread elements.