Patent ID: 8087420

Claim:
A gravity-powered, and self-opening umbrella system, comprising: a static component including a pole having a top portion; a dynamic component including a retractable umbrella covering having a center and an outer edge, the center attached to the top portion of the pole; a plurality of ribs for supporting the umbrella covering; a runner circumscribing the pole, adapted to slide vertically on the pole and coupled to the plurality of ribs through a plurality of stretchers; and, a user rope having a fixed-end and a user-end, the user end receiving a force, F 1 , applied by a user to close the umbrella covering, the fixed end of the user rope operably attached to the runner; a counterweight component to provide a gravitational force, F 2 , and, a compound pulley component including at least one class-1 pulley attached to the static component; at least one class-2 pulley attached to the dynamic component; and, a pulley rope (i) having a fixed end and a weighted end attached to the counterweight component, and (ii) in operable connection with the pulleys to provide a mechanical advantage to the umbrella system, the fixed end of the pulley rope operably attached to the static component above the class-2 pulley; wherein, F 2 is substantially greater than f t +0.5 F 3 for a self-opening of the umbrella covering; F 3 is an upward vertical force on the runner, in the absence of any friction, applied to open the umbrella covering; and, f t is the total frictional force in the system realized at the counterweight component.