Patent ID: 7909049

Claim:
An operating mechanism used in an umbrella comprising a hub and rib assembly, a runner, a plurality of stretchers pivotally connected between ribs of said hub and rib assembly and said runner, and a canopy stretched on said hub and rib assembly, said operating mechanism being operable to move said runner against said stretchers to further force said ribs of said hub and rib assembly to open/close said canopy, said operating mechanism comprising a first screw rod, a second screw rod, a third screw rod, a first screw nut, a second screw nut, a third screw nut, a telescopic shaft and a transmission mechanism, wherein: said first screw nut and said second screw nut are respectively fixedly mounted inside said telescopic shaft at different elevations; said third screw nut is fixedly mounted in said runner; said first screw rod is threaded through said first screw nut and inserted into said second screw rod, said first screw rod having a gear fixedly located on one end thereof and meshed with said transmission mechanism and a longitudinal sliding groove for guiding axial movement of said second screw rod relative to said first screw rod; said second screw rod is threaded through said second screw nut, said second screw rod comprising a longitudinal sliding groove for guiding axial movement of said third screw rod relative to said second screw rod; said third screw rod is threaded through said third screw nut, said third screw rod comprising a longitudinal rib axially slidably coupled to the longitudinal sliding groove of said second screw rod; said telescopic shaft comprises a plurality of tubular shaft elements numbered from 1 through 5 and set to slide one inside another, the fifth tubular shaft element of said telescopic shaft being inserted through said runner; said transmission mechanism is connected to one end of said first screw rod and operable to rotate said first screw rod.