fig1 shows the preferred embodiment of this invention in its most frequently deployed position . an umbrella 20 is mounted to a stand 21 to support a central pole 22 with the axis in an upright position . instead of a stand , sockets or other types of support can as readily be used . persons 23 and objects such as tables and chairs can conveniently be sheltered under the umbrella . a table 24 is suggested by a broken line in fig1 . as shown in fig1 , the umbrella includes a canopy 25 which is preferably rectangular so that when deployed it will form a dihedral angle with a ridge 26 ( more properly , an “ edge ” of a dihedral ) with a pair of rectangular faces 27 , 28 . it is a feature of this invention that the dihedral angle between the faces can be adjusted , even to the extent that it is 180 degrees ( a flat plane ). more usually the dihedral will be on the value of about 120 degrees . it is of interest that with this rectangular arrangement , a 9 foot by 9 foot square umbrella can provide as much shade as an 11 foot diameter round umbrella . this can provide important advantages when placing tables and umbrellas in rows , giving them as much shade with minimized side interference and greater uniformity . the canopy is made of flexible material so it can be bent or folded . most common fabrics have some limited elasticity , which assists the canopy to form flat panels when stretched at the corners . woven fabric is a recognized material for such fabrics . the canopy ( shown as a flat layout in fig3 ) has outer edges 31 , 32 , 33 and 34 , generally arrayed as a rectangle or square although there may occasionally be reasons to form them other than as straight lines . these edges form four corners 35 , 36 , 37 and 38 . in the center of the canopy an open vent port 40 is formed . as will be evident , it is convenient for it to be formed as a rectangle or square but this is not a limitation on the invention . preferably in plan view it is disposed at a 90 degree angle to the outside perimeter of the canopy . the vent port has edges 41 , 42 , 43 and 44 . a vent cover 50 rests stop the canopy , with a perimeter 51 geometrically similar to the vent port , but with larger lateral dimensions so that it will overhang the vent port , especially when the umbrella is deployed . it is made of material similar to the canopy and is locally attached to the canopy at places to be described below . of particular interest is that a triangular cover panel 52 , 53 is formed loosely on each side of the ridge line 26 with corners 55 and 56 farthest from the ridge line . a cap 60 is attached to the pole above the canopy and vent cover so as to cover and protect the first hub and the pole from drainage . except at its center it is loose from the vent cover , and is not relied on for a venting function . as shown in fig2 , which illustrates the retracted condition , the cap , vent cover and canopy are all suspended in various direct and indirect ways from the pole . deployment is accomplished by selective movement of the second and third hubs whose movement along the pole deploys or retracts these flexible sheets . deployment and retraction are accomplished by changing the axial location of hubs along the pole . a first hub 65 is fixed at or near the top of the pole . as best shown in fig4 - 7 , which show the actuator structure without the canopy or vent cover for clarity , this first hub provides hinges for eight rods . ridge former rods 66 and 67 are hinged at one end for vertical movement ( as do all of the rods described herein ) and extend radially away from one another . when deployed they will be horizontal and will form the ridges the canopy and vent cover draping over them . two pairs of canopy rods 70 , 71 , 72 , 73 are hinged to the first hub and extend away in the direction of canopy corners , as will become apparent . one pair of vent cover rods 74 , 75 is hinged to the first hub , extending in the direction of cover corners . a second hub 80 is slidably fitted on the pole for movement up and down along it . this hub is for the purpose of controlling the ridge former rods . two ridge former struts 81 and 82 are hingedly connected to the second hub and to a mid location on respective ridge former rods . thus , up and down movement of the second hub will move the struts to cause the ridge former rods to deploy to form the ridge or retract to collapse the umbrella . a third hub 90 is similarly slidably fitted on the pole . it is for the purpose of controlling the position of the canopy rods and the vent cover rods . this hub is effective when the second hub is raised . for this purpose , two pairs of canopy struts 91 , 92 , 93 , 94 are hingedly mounted at one end to the third hub and at the other end to mid positions on the canopy rods . up and down movement of the second hub raises and lowers the ridge former rods . a pair of vent cover struts 96 , 97 are also hingedly attached to the third hub at one of their ends . their other end is hingedly attached to a mid point on a respective vent cover rod . these struts pass through the vent port to move the vent cover rods . for clarity of disclosure the canopy and vent cover are either omitted from some drawings , or shown only in thin line . the umbrella is assembled by attaching rods to the canopy and vent cover and attaching the vent cover to the canopy at the ridge , as will be disclosed . there are three basic conditions of this umbrella . the retracted condition is shown in fig2 . the first hub is fixed , the second and third hubs are at their lowest position . all struts and rods have been retracted and brought toward the pole . the fabric material ( canopy and vent cover ) are sufficiently attached that all hangs down loosely , but are suspended . to deploy the umbrella to the position of fig1 , both the second and third hubs rise together and stop at the position shown in fig3 and 4 . the second hub ( for the ridge former rods ) will always stop here . a stop such as a pin or other mechanism ( not shown ) to restrain them from lowering will be supplied for this . to raise the canopy further , the third hub must be raised higher , leaving the second hub where it is . if the height of the third hub is at an inconvenient reach , a wand 100 may be attached to it , hanging down where it can be grasped and pushed upwardly to raise the third hub . a handle 101 is provided for this . also , if desired a restraint 102 can be provided to rest on the second hub when the canopy is flat , to hold the third hub in its raised position at that time . a comparison of fig5 and 7 illustrates the differences in positions of the rods and struts in the two deployed conditions . what is of most importance is that the vent cover moves when the canopy moves , and is always under positive position control . as to attachment of the canopy and vent cover to the rods , the remote , second ends of the canopy rods will be placed in pockets , or otherwise attached to the canopy near its corners . the vent cover rods will be placed in pockets or otherwise attached to the vent cover near the “ points ” removed from the ridge . attachment of the canopy to the ridge former rods is done to assure that the canopy is properly placed on the ridge and does not slide away when the umbrella is retracted . fasteners ( not shown ) along the ridge will usually be used . the vent cover must stay with the canopy , so it may be stitched or otherwise fastened to the canopy at suitable places along the ridge . positions intermediate between the dihedral of fig1 and the flat plane of fig7 may be used provided means is present to hold the third hub at a selected height between the two positions . this invention provides a versatile and attractive umbrella with advantages of shape and deployed conditions , easy storage , and a rugged assembly . the various parts may be such as aluminum tubing and extrusions and plastic parts where advantageous , such as for hubs and hinges . this invention is not to be limited by the embodiment shown in the drawings and described in the description , which is given by way of example and not of limitation , but only in accordance with the scope of the appended claims .
an umbrella assembly providing a dihedral shelter atop a pole which can be deployed to different dihedral angles and retracted to a compact configuration . it further includes a vent port in a cavity which is overhung by a positively positioned vent port cover .