US Patent 11492846 Window blind assembly having transmission assist structure

A window blind assembly includes a frame, an input shaft rotatably disposed in the frame, a blind unit, a winding unit for placing the blind unit in a retracted state when the input shaft is rotated in a first rotational direction and for shifting the blind unit to an expanded state when the input shaft is rotated in a second rotational direction, a control unit operable to drive rotation of the input shaft in the first and second rotational directions, a force-assisting unit having a spring capable of exerting a spring force on the control unit to resist the weight of the blind unit acting thereon, and a brake unit connected to the input shaft and generating a frictional force to resist rotation of the input shaft in the second rotational direction.