Ball joint base and twist lock for slideable concentric members adapted for use in umbrellas with extensible canopy ribs

1. An umbrella comprising:

a canopy supported by a plurality of ribs;

an upper pole having an upper end carrying the canopy;

a lower pole having a lower end connected to a base, said upper pole and lower pole being concentric sliding members interfitting concentrically in a slidable fashion;

stretchers extending outward from the upper pole and supporting a plurality of ribs; and

a twist lock for engaging concentric sliding members;

wherein the twist lock comprises a mechanism on a first exterior member having:

a top cap threaded on the interior to receive a bottom cap threaded on the exterior and having a downward facing normal interior surface and downward facing inclined interior surface;

a base support received within the top cap having an upward facing normal surface below the downward facing inclined interior surface and upward facing inclined surface below the downward facing normal interior surface;

a lock ring biased to a normal position intermediate the upward and downward facing surfaces;

a longitudinally moveable post extendable through the upward facing normal surface; and

the bottom cap having an upward facing portion that restrains and pushes on a base of the post.

2. The umbrella of claim 1 wherein the first exterior member overfits a second interior member and the tightening of the top and bottom cap members on the first exterior member urges a lock ring held within the top cap into angled engagement with the second interior member, fixing its position relative to the first exterior member.

3. The umbrella of claim 2 wherein the base has a ball joint.

4. The umbrella of claim 2 wherein the base has a plurality of openings that receive spikes.

5. The umbrella of claim 2 wherein the base has an anchor.

6. The umbrella of claim 2 wherein the canopy has a width in excess of eight feet, and the plurality of ribs are extensible ribs formed of at least two longitudinal rib parts, each having a length of less than 45 inches, that are joined together to form a rib having a length in excess of 48 inches.

7. An umbrella comprising:

a canopy supported by a plurality of ribs;

an upper pole having an upper end carrying the canopy;

a lower pole having a lower end connected to a base, said upper pole and lower pole being first and second concentric sliding members interfitting concentrically in a slidable fashion;

stretchers extending outward from the upper pole and supporting a plurality of ribs; and

a twist lock for engaging concentric sliding members;

the lower end of the lower pole comprising a ball stud having a generally spherical end and a longitudinally protruding stud;

wherein the base has a ball sleeve with a spherical surface receiving the spherical end of the ball stud and

wherein the twist lock comprises a housing with an inner fitting split wedge collar associated with first concentric sliding member and a threaded shim with an interior angled surface positioned interior the housing and over the split wedge collar, said threaded shim being connected with second concentric sliding member.

8. The umbrella of claim 7 wherein the spherical end has a plastic surface with a Shore A durometer of between about 85 and 110.

9. The umbrella of claim 7 wherein a top friction race, with a segment of spherical inner surface and a central opening through which the protruding stud passes, is fastened to the ball sleeve so that the spherical end is constrained between the ball sleeve and friction race, and the size of the central opening and protruding stud are optimized to allow at least 30 degrees of angular movement by the protruding stud from the vertical toward the horizontal.

10. The umbrella of claim 7 wherein the ball sleeve has a threaded outer portion and a collar with inner threads and a central opening overfits the top friction race and fastens the friction race to the ball sleeve.

11. The umbrella of claim 7 wherein engaging and tightening the inner threads of the collar with the threaded outer portion of the ball sleeve applies a frictional grip to the spherical end of the ball stud so that the ball stud resists movement when a force of at least 60 newtons applied to the lower pole at a distance of one meter above the base.

12. The umbrella of claim 7 wherein the plurality of ribs are extensible ribs formed of at least two longitudinal rib parts.

13. The umbrella of claim 7 wherein the ball sleeve is fabricated from aluminum.