US Patent 7219710 Lifting mechanism for window shades

Provided is a lifting mechanism for a shade including a plurality of continuous slats and two lift cords. The mechanism comprises a winding assembly, and a hoisting assembly fixedly attached to an inner surface of a lowest slat, the hoisting assembly comprising an elongated, hollow member of rectangular section including a bottom rectangular opening and two holes on its upper surface proximate both ends of the opening, and a channel fitted in the hollow member, the channel including a plurality of rollers across two raised walls thereof. The winding assembly is fixedly attached to an outer surface of the lowest slat. Either lift cord has one end terminated at a left (or right) portion of a topmost slat and the other end terminated at the winding assembly by passing left (or right) portions of the slats.