Umbrella

Abstract

An umbrella includes a runner slidably mounted on a central shaft to spread and collapse rib-and-stretcher units to which a canopy is mounted. Each rib-and-stretcher unit includes a support rib, a stretcher, and an extension rib. When the runner is moved from an upper position to an uppermost position, each extension rib is driven to slide outwardly relative to a corresponding support rib via a pivot connection between a corresponding stretcher and the extension rib, and a main portion of the canopy is moved together with the extension ribs to outwardly draw a central portion of the canopy, which movably surrounds the central shaft, to partially cover each support rib.

What is claimed  is: 
     
         1 . An umbrella comprising:
 a central shaft extending in an axial direction;   a hub unit mounted to an end of said central shaft;   a runner surrounding said central shaft and movable relative to said central shaft in the axial direction between an upper position and a lower position;   a plurality of angularly spaced-apart rib-and-stretcher units surrounding said central shaft, each of said rib-and-stretcher units including
 a support rib that has a first end pivotally connected to said central shaft at a position adjacent to said hub unit and a second end opposite to said first end, 
 an extension rib that has a proximate end slidably connected to said support rib adjacent to said second end of said support rib, and a distal end that is opposite to said proximate end; and 
 a stretcher that has a first end pivotally connected to said runner and a second end opposite to said first end of said stretcher and pivotally connected to said proximate end of said extension rib, 
   a canopy mounted on said rib-and-stretcher units and including
 a main portion, that covers said support ribs and said extension ribs and that is connected fixedly to said distal end of said extension rib of each of said rib-and-stretcher units, and 
 a central portion that interconnects said main portion of said canopy and said hub unit and that surrounds movably said central shaft; 
   wherein, when said runner is moved from the lower position to the upper position, said support rib and said extension rib of each of said rib-and-stretcher units are driven to spread relative to said central shaft via the pivot connections among said central shaft, said runner and said rib-and-stretcher units; and   wherein, when said runner is further moved along said central shaft from the upper position toward said end of said central shaft to an uppermost position, said extension rib of each of said rib-and-stretcher units is driven to slide outwardly relative to said support rib of a corresponding one of said rib-and-stretcher units via the pivot connection between said stretcher of the corresponding one of said rib-and-stretcher units and said proximate end of said extension rib, and said main portion of said canopy is moved together with said extension ribs to draw said central portion outwardly to partially cover said support ribs; and   a positioning mechanism disposed on said central shaft for positioning said support ribs relative to said central shaft during movement of said runner between the upper and uppermost positions.   
     
     
         2 . The umbrella as claimed in  claim 1 , wherein said hub unit includes:
 a housing mounted fixedly to said end of said central shaft and receiving a portion of said central shaft therein;   an abutment member disposed in said housing, connected fixedly to said central portion of said canopy, and slidable relative to said portion of said central shaft in the axial direction; and   a biasing member disposed in said housing and connected to said abutment member for biasing said abutment member toward said end of said central shaft.   
     
     
         3 . The umbrella as claimed in  claim 2 , wherein said housing includes a main wall mounted to said end of said central shaft and a ring-shaped wall connected to a bottom end of said main wall, said portion of said central shaft extending through said ring-shaped wall into said housing, and said biasing member having opposite ends that abut respectively against said abutment member and said ring-shaped wall. 
     
     
         4 . The umbrella as claimed in  claim 3 , wherein said biasing member is a compression spring. 
     
     
         5 . The umbrella as claimed in  claim 2 , wherein said housing includes a main wall receiving said portion of said central shaft and having a top wall section that is mounted to said end of said central shaft, said biasing member having opposite ends that are connected respectively to said abutment member and said top wall section. 
     
     
         6 . The umbrella as claimed in  claim 5 , wherein said biasing member is an extension spring. 
     
     
         7 . The umbrella as claimed in  claim 1 , further comprising a handle and a telescopic shaft unit interconnecting said handle and an opposite end of said central shaft that is opposite to said end of said central shaft in the axial direction so that a distance between said handle and said central shaft is adjustable.