Venetian blind, preferably a vertical blind

Abstract From the Canadian patent

A vertical venetian blind includes a driving shaft a plurality of slat travellers each having a driven member and a slip coupling for connecting the driving shaft to the driven member and a plurality of slats each connected to each driven member. The slip coupling includes a bushing mounted on the driving shaft to rotate with and to slide along the driving shaft, and a worm tightly enclosing the bushing and having a screw thread. The driven member includes a worm wheel and two stop cams for contacting ends of the screw thread. The worm can slip with respect to the bushing when the driving shaft rotates and one end of the screw thread contacts one of the cams or the other end of the screw …