US Patent 10030442 Spring system for roller blinds

A spring assist module for window covering includes a stationary member, at least one torsion spring, and at least one rotatable member. The stationary member may be connectable to an operating member of the window covering. The at least one rotatable member may be keyable to a driven part of the window covering, such that rotation of the driven part rotates the at least one rotatable member. The at least one torsion spring may include a first end operatively coupled to the stationary member and a second end operatively coupled to the at least one rotatable member. The spring assist module may be pre-assembled as a self-contained unit.