Wrap spring shade operator

Abstract

A profile positioning system employing a wrap spring clutch system, the system includes a shade operator, a shade roller and an unloaded end bracket for supporting the shade roller during installation. The shade operator consists of: a self-lubricating central stud around which a helical spring is coiled; a manually operated pulley mounted on the coiled spring; and a backing bush to ensure positive engagement of the above elements set. The center stud consists of a plastic or metal that allows the coil spring around the stud to rotate smoothly. The tang of the wrap spring protrudes substantially radially outward from the central axis of the spring and is shaped to accommodate the coefficient of friction between the stud and the spring. A first preferred spring configuration reduces the surface area of ​​the spring in contact with the stud. A second preferred spring configuration increases the surface area of ​​the spring in contact with the stud. In addition, a protrusion is provided on the bushing, and due to the gravity of the shade, the protrusion can be engaged with the winding spring. This engagement allows the spring to further grip the stud, preventing the pulley from rotating.

Description

technical field [0001] This invention relates to apparatus for operating and positioning a shade and, more particularly, to a manually operated shade positioning system incorporating a wrap spring clutch system. Background technique [0002] Various wrap spring clutch systems for operating shades have been developed and are familiar to those skilled in the art. These clutch systems typically employ: a fixed cylindrical central shaft or stud around which a coil spring is positioned; a rotating drive member that controls the inner diameter of the coil spring; and a bushing that ensures Engagement of shafts, springs and rotating members. During operation of a typical wrap spring system, rotation of the rotary drive member increases the inner diameter of the wrap spring, which reduces friction between the central shaft and the wrap spring, thereby optionally reducing or Raise the shade. [0003] US Patent No. 4,779,662, issued to Wilk on October 25, 1988, is a typical example...

AI Technical Summary

Problems solved by technology

A limitation of the Nisenson patent is that it uses a plastic coil spring structure which is generally not as robust and reliable over sustained periods of operation as clutch systems using metal springs

The lack of robustness and reliability inherent in plastic springs generally increases the slack spring inner diameter with continued use and thus increases the stair step effect

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