US Patent 10138678 Spring system for roller blinds

A method of selecting one or more springs for a roller blind is provided. The method may include determining one or more parameters of the blind, determining a torque curve of the blind based on the one or more parameters of the blind, and selecting one or more springs having a wire diameter and a spring diameter. The method may further include determining a length of the one or more springs based on the torque curve, the wire diameter of the one or more springs, and the spring diameter of the one or more springs to ensure the blind operates with a constant operating force.