Patent ID: 8708024
Filing Date: 2014-04-29
Classification: E06B,Y10T

Abstract:
1. A method for operating a window cover, the method comprising: providing an extendable window cover comprising a first rail, a second rail, and a pair of lift cords, wherein the first and second rails of the window cover are movable relative to each other; providing a spring drive system that is operably coupled to the lift cords, wherein the spring drive system comprises a lift cord pulley shaft coupled to a pair of spaced apart lift pulleys, wherein the lift cords are operably coupled to the lift cord pulleys, a spring drive unit having a beveled gear system with a first gear that is meshed with a second gear, wherein the lift cord pulley shaft extends through the second gear and is configured to rotate therewith, and wherein the spring drive unit is positioned between the two lift pulleys; moving at least one of the first rail and the second rail in a first direction to cause the lift cords to unwind from the lift cord pulleys, thereby rotating the lift cord pulley shaft and the first and second gears; and moving at least one of the first rail and the second rail in a second direction to cause the lift cords to wind on the lift cord pulleys, with the lift cord pulley shaft rotating in an opposite direction, and with the spring drive unit assisting with the movement by applying torque to the first gear.