Cordless retractable roller shade for window coverings

摘要

A cordless retractable shade including an operating system for the shade that varies a biasing force of a spring to counterbalance the shade. The bottom rail of a retractable shade can be raised or lowered, and due to the operating system remains in any selected position of the covering between fully extended and fully retracted, without the use of operating cords. The system includes a method of negating and reversing the spring bias effect at a strategic position whereby the flexible vanes of the shade can be adjusted between open and closed.

主权项

1. A cordless retractable shade comprising:
a rotatable roller; a shade material operably connected to the roller, wherein the shade material is wrappable about and unwrappable from the roller for retraction and extension of the shade material, respectively; a biasing component operably connected to the roller and configured to exert a variable biasing force on the roller in a retraction direction to at least counterbalance a weight of that portion of the shade material that is unwrapped from the roller, wherein the biasing component is configured to apply greater amounts of force to the roller as greater amounts of the shade material are unwrapped from the roller; a non-rotatable shaft positioned within the roller; and a nut mounted onto the non-rotatable shaft and keyed to the roller such that rotation of the roller translates the nut along a length of the non-rotatable shaft, wherein at an end point of travel of the shade material into an extended position, the nut engages a stop disposed on the non-rotatable shaft to restrict retraction of the shade material and wherein the nut is disengaged from the stop by movement of the roller in the retraction direction.