Patent Publication Number: US-7913709-B2

Title: Umbrella

Description:
TECHNICAL FIELD 
     This invention relates to umbrellas and in particular though not solely to canopy extension and tensioning mechanisms for umbrellas. 
     BACKGROUND ART 
     Umbrellas may be used to protect a user from the sun, wind or rain and may be portable or designed to be fixed to the ground (such as sun umbrellas having generally larger dimensions than portable rain umbrellas). 
     Fundamentally, the basic design of umbrellas has not changed in the past three centuries. Conventional umbrellas include a shaft to which a canopy is attached at one end and a handle is attached at the other end. A collapsible frame is included to support the canopy and which, when not in use, allows itself and the canopy to be lowered into a more compact state which may more easily be stored. 
     The collapsible frame consists of a number of ribs (usually eight ribs) evenly radially distributed about the shaft and pivotally connected at their inner ends to the canopy end of the shaft. The perimeter of the canopy is attached (often simply tied by threads) to the outer ends of each of the ribs. The end of each rib is generally exposed and provided with a stopper or other blunting device. In many umbrellas, in order to assist in raising/lowering the ribs and holding them in position, each rib is provided with a brace or strut which is pivotally connected at one of its ends to a point along the rib&#39;s length and at its other end it is pivotally connected to a slider which is slidable along the shaft. The slider is lockable in position near the canopy end of the shaft when in use. 
     Minor improvements have been made to the above described basic umbrella design for improved user convenience. Improvements include push-button self-erecting mechanisms usually incorporating a spring in which energy stored during collapsing of the umbrella is utilised to move the slider up the shaft to thereby erect the umbrella. Another relatively recent improvement is the provision of umbrellas which “fold down” to fit within a hand bag or briefcase for example. Umbrellas of this variety usually include a multi-segment shaft in which successive segments are a slide-fit within preceding segments. Further reductions in size are achieved by the use of multi-segmented canopy supporting ribs which are pivotally connected together and are collapsible in ‘V’ or ‘W’ shaped formations. 
     Problems with the above described conventional design (and its minor improvements) include the exposed rib ends which when in use, are positioned at or about eye level of passers-by and therefore pose a safety hazard. Also, in strong wind conditions the canopy may become detached from the frame while the frame has a tendency to turn inside-out, often resulting in irreparable damage to the umbrella frame and/or canopy. 
     It is also noted that in most if not all conventional umbrella designs, the canopy material is not optimally tensioned. This is because during erection of umbrellas having conventional frame designs, the vertical force provided by the user on the shaft slider is converted to compressive forces acting on the struts which in turn inefficiently convert the vertical force into a radially outwardly directed canopy tension. As the umbrella approaches its completely erect state, the struts (which support the ribs) approach the horizontal such that the majority of the effort being exerted by the user (the horizontal component of the strut force) is not being used while only a small proportion of the user&#39;s effort (the vertical component of the strut force) is usefully being employed in tensioning the canopy. This is readily observed when erecting conventional umbrellas in which resistance to shaft slider movement becomes increasingly apparent at the end of the slider&#39;s travel despite the rate of change of angle between rib and shaft reducing. Accordingly, in conventional umbrella designs, tension which could usefully be employed in the canopy is wasted in the ribs. 
     It would also be an advantage if an umbrella and/or umbrella frame could be developed in which the canopy could easily be replaced should it be desired or necessary. 
     It is therefore an object of the present invention to provide an umbrella and/or umbrella frame which will go at least some way towards overcoming the above disadvantages or addressing the above problems or which will at least provide the public with a useful choice. 
     All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinence of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country. 
     It is acknowledged that the term ‘comprise’ may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, the term ‘comprise’ shall have an inclusive meaning—i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements. This rationale will also be used when the term ‘comprised’ or ‘comprising’ is used in relation to one or more steps in a method or process. 
     DISCLOSURE OF INVENTION 
     Accordingly, in a first aspect the invention consists in an umbrella comprising: 
     a shaft, 
     a plurality of rib members, first ends of said rib members spaced about and pivotally connected at or adjacent a first end of said shaft, 
     a canopy including pocket means at or adjacent to the periphery of the canopy wherein an opening or openings in the pocket means is accessible from the direction of the central portion of the canopy, 
     a sliding means movable along the shaft to erect or collapse the umbrella, 
     a plurality of struts, each of which is pivotally connected between the sliding means and a rib member, and 
     force spreading means provided on a second end of each rib member, the force spreading means received within the pocket means of the canopy. 
     Preferably, the inside of the or each pocket means, at least opposite to the opening, is closed to provide a bearing surface upon which the force spreading means contacts. 
     Preferably, said pocket means comprise a plurality of separate pockets spaced about the canopy&#39;s periphery, wherein one force spreading means is received within each pocket. 
     Preferably, a closed edge of each pocket lies along the periphery of the canopy and the opening in each pocket is in the form of a slit substantially aligned with its rib member. 
     Preferably, the periphery of each pocket is closed. 
     Preferably, a secondary sliding means movable along the shaft between said sliding means and the first end of said shaft, and a plurality of secondary struts each pivotally connected between said secondary sliding means and a respective strut are also provided. 
     Preferably, said secondary struts are about half as long as the struts. 
     Preferably, said secondary struts are about 15/26 times the length of the struts. 
     Preferably, each secondary strut is connected to a strut a pre-determined distance from its connection with said sliding means, wherein said pre-determined distance is substantially equal to the length of said secondary strut. 
     Preferably, the sliding means includes a spacing means above the position on the sliding means at which the struts are connected and which, during erection of the umbrella, contacts and pushes the secondary sliding means and once the umbrella has reached a fully erected state, fixes the spacing between the sliding means and secondary sliding means. 
     Preferably, during erection of the umbrella, holding means temporarily hold the secondary sliding means in position at a predetermined location along the shaft before releasing the secondary sliding means once the sliding means has moved a predetermined distance towards the secondary sliding means. 
     Preferably, each rib member includes an inner rod means extending between the shaft and a force spreading means and an outer tube slidable on said inner rod means wherein each outer tube is pivotally connected to a strut. 
     Preferably, each force spreading means includes a load spreading surface adapted to transfer radial force from the outer tube of said rib member to the periphery of said canopy via said pocket means. 
     Preferably, the amount of contact between said canopy and said load spreading surface increases during erection of said umbrella. 
     Preferably, said force spreading means comprises two legs pivotally connected together at a pivot region and forming a substantially ‘V’ shape when said umbrella is in a collapsed state and wherein said legs are spread apart and substantially aligned during erection of said umbrella, the two legs and the pivot region forming said load spreading surface. 
     Preferably, the outer end of an inner rod means contacts the pivot region of a force spreading means and the outer end of an outer tube is connected to both of the legs of said force spreading means. 
     Preferably, the outer end of an inner rod means is received within a longitudinal bore provided in a stopper connected to or forming a part of the pivot region of a force spreading means. 
     Preferably, each force spreading means includes first and second spreading members, each pivotally connected to a respective pivotally connected leg and non-pivotally connected to a tube mounting hub of said force spreading means, the tube mounting hub connected to the outer end of said outer tube, said inner rod means passing through the tube mounting hub. 
     Preferably, said force spreading means is formed from a plastics material and wherein living hinges form the pivotal connections therein. 
     Preferably, the inner rod means comprises more than one separate inner rod portion placed end to end within an outer tube. 
     Preferably, an inner rod portion furthest from the shaft has a lower weight per unit length than an inner rod portion closer to the shaft. 
     Preferably, no more than six rib members are provided about said shaft. 
     In a second aspect, the invention consists in an umbrella frame comprising: 
     a shaft, 
     a plurality of rib members, first ends of said rib members spaced about and pivotally connected at or adjacent a first end of said shaft, 
     a primary sliding means movable along the shaft to erect or collapse the umbrella frame, 
     a secondary sliding means movable along the shaft between the primary sliding means and the first end of the shaft, 
     a plurality of primary struts, each of which is pivotally connected between the primary sliding means and a rib member, and 
     a plurality of secondary struts, each of which is pivotally connected between the secondary sliding means and a primary strut. 
     Preferably, a force spreading means is provided on a second end of each rib member. 
     Preferably, said secondary struts are about half as long as the primary struts. 
     Preferably, said secondary struts are about 15/26 times the length of the primary struts. 
     Preferably, each secondary strut is connected to a primary strut a pre-determined distance from its connection with said primary sliding means, wherein said pre-determined distance is substantially equal to the length of said secondary strut. 
     Preferably, the primary sliding means includes a spacing means above the position on the primary sliding means at which the primary struts are connected and which, during erection of the umbrella frame, contacts and pushes the secondary sliding means and once the umbrella frame has reached a fully erected state, fixes the spacing between the primary sliding means and secondary sliding means. 
     Preferably, during erection of the umbrella frame, holding means temporarily hold the secondary sliding means in position at a predetermined location along the shaft before releasing the secondary sliding means once the primary sliding means has moved a predetermined distance towards the secondary sliding means. 
     Preferably, each rib member includes an inner rod means extending between the shaft and a force spreading means and an outer tube slidable on said inner rod means wherein each outer tube is pivotally connected to a primary strut. 
     Preferably, a force spreading means is provided on a second end of each rib member, each force spreading means including a load spreading surface adapted to transfer radial force from the outer tube of said rib member to the periphery of a canopy adapted to be supported by the umbrella frame. 
     Preferably, the effective length or contact area of said load spreading surface increases during erection of said umbrella frame. 
     Preferably, said force spreading means comprises two legs pivotally connected together at a pivot region and forming a substantially ‘V’ shape when said umbrella frame is in a collapsed state and wherein said legs are spread apart and substantially aligned during erection of said umbrella frame, the two legs and the pivot region forming said load spreading surface. 
     Preferably, the outer end of an inner rod means contacts the pivot region of a force spreading means and the outer end of an outer tube is connected to both of the legs of said force spreading means. 
     Preferably, the outer end of an inner rod means is received within a longitudinal bore provided in a stopper connected to or forming a part of the pivot region of a force spreading means. 
     Preferably, each force spreading means includes first and second spreading members, each pivotally connected to a respective pivotally connected leg and non-pivotally connected to a tube mounting hub of said force spreading means, the tube mounting hub connected to the outer end of said outer tube, said inner rod means passing through the tube mounting hub. 
     Preferably, said force spreading means is formed from a plastics material and wherein living hinges form the pivotal connections therein. 
     Preferably, the inner rod means comprises more than one separate inner rod portion placed end to end within an outer tube. 
     Preferably, an inner rod portion furthest from the shaft has a lower weight per unit length than an inner rod portion closer to the shaft. 
     Preferably, no more than six rib members are provided about said shaft. 
     In a third aspect, the invention consists in an umbrella frame comprising: 
     a shaft, 
     a plurality of rib members spaced about said shaft, each rib member including a first portion pivotally connected at or adjacent a first end of said shaft and a second portion freely slidable relative to said first portion, 
     a sliding means movable along the shaft to erect or collapse the umbrella frame, and 
     a plurality of struts, each of which is pivotally connected between the sliding means and the second portion of said rib member. 
     Preferably, a secondary sliding means movable along the shaft between said sliding means and the first end of said shaft, and a plurality of secondary struts each pivotally connected between said secondary sliding means and a respective strut are also provided. 
     Preferably, said secondary struts are about half as long as the struts. 
     Preferably, said secondary struts are about 15/26 times the length of the struts. 
     Preferably, each secondary strut is connected to a strut a pre-determined distance from its connection with said sliding means, wherein said pre-determined distance is substantially equal to the length of said secondary strut. 
     Preferably, the sliding means includes a spacing means above the position on the sliding means at which the struts are connected and which, during erection of the umbrella frame, contacts and pushes the secondary sliding means and once the umbrella frame has reached a fully erected state, fixes the spacing between the sliding means and secondary sliding means. 
     Preferably, during erection of the umbrella frame, holding means temporarily hold the secondary sliding means in position at a predetermined location along the shaft before releasing the secondary sliding means once the sliding means has moved a predetermined distance towards the secondary sliding means. 
     Preferably, a force spreading means is provided on the end of each rib member furthest from the shaft. 
     Preferably, the first portion of each rib member includes an inner rod means extending between the shaft and a force spreading means and an outer tube slidable on said inner rod means wherein each outer tube is pivotally connected to a strut. 
     Preferably, each force spreading means includes a load spreading surface adapted to transfer radial force from the outer tube of said rib member to the periphery of a canopy adapted to be supported by the umbrella frame. 
     Preferably, the effective length or contact area of said load spreading surface increases during erection of said umbrella frame. 
     Preferably, said force spreading means comprises two legs pivotally connected together at a pivot region and forming a substantially ‘V’ shape when said umbrella frame is in a collapsed state and wherein said legs are spread apart and substantially aligned during erection of said umbrella frame, the two legs and the pivot region forming said load spreading surface. 
     Preferably, the outer end of an inner rod means contacts the pivot region of a force spreading means and the outer end of an outer tube is connected to both of the legs of said force spreading means. 
     Preferably, the outer end of an inner rod means is received within a longitudinal bore provided in a stopper connected to or forming a part of the pivot region of a force spreading means. 
     Preferably, each force spreading means includes first and second spreading members, each pivotally connected to a respective pivotally connected leg and non-pivotally connected to a tube mounting hub of said force spreading means, the tube mounting hub connected to the outer end of said outer tube, said inner rod means passing through the tube mounting hub. 
     Preferably, said force spreading means is formed from a plastics material and wherein living hinges form the pivotal connections therein. 
     Preferably, the inner rod means comprises more than one separate inner rod portion placed end to end within an outer tube. 
     Preferably, an inner rod portion furthest from the shaft has a lower weight per unit length than an inner rod portion closer to the shaft. 
     Preferably, no more than six rib members are provided about said shaft. 
     In a further aspect, the invention consists in an umbrella including a canopy supported by an umbrella frame according to the second or third aspects. 
     Preferably, the canopy includes pocket means at or adjacent to the periphery of the canopy wherein an opening or openings in the pocket means is accessible from the direction of the central portion of the canopy. 
     Preferably, the inside of the or each pocket means, at least opposite to the opening, is closed to provide a bearing surface upon which the force spreading means contacts. 
     Preferably, a force spreading means is provided on the end of each rib member furthest from the shaft, wherein said pocket means comprise a plurality of separate pockets spaced about the canopy&#39;s periphery, and wherein one force spreading means is received within each pocket. 
     Preferably, a closed edge of each pocket lies along the periphery of the canopy and the opening in each pocket is in the form of a slit substantially aligned with its rib member. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Further aspects of the present invention will become apparent from the following description which is given by way of example only and with reference to the accompanying drawings in which: 
         FIG. 1  is a perspective view from beneath of an umbrella according to a preferred embodiment of the present invention; 
         FIG. 2  is an enlarged perspective view of the main components of the canopy extending and tensioning means or mechanism of the umbrella of  FIG. 1 , 
         FIGS. 3A to 3E  are a series of perspective views from the front and slightly above of the umbrella of  FIG. 1  without its canopy, showing the actions of the components of the canopy extending and tensioning mechanism at various stages during erection of the umbrella, 
         FIGS. 4A to 4E  are a series of side elevational views corresponding to  FIGS. 3A to 3E  showing the action of a single rib and its associated struts and sliders at various stages during erection of the umbrella of  FIG. 1 , and 
         FIGS. 5A to 5E  are a series of perspective views of the force spreading means of the umbrella of  FIG. 1  at various stages during erection of the umbrella of  FIG. 1 , 
         FIGS. 6A to 6E  are a series of front elevational views corresponding to  FIGS. 3A to 3E  and  4 A to  4 E showing the action of a single rib and its associated struts during erection of the umbrella of  FIG. 1 , and 
         FIGS. 7A to 7D  are a series of close-up perspective views of the shaft, struts and sliders at various stages during erection of the umbrella of  FIG. 1 . 
     
    
    
     BEST MODES FOR CARRYING OUT THE INVENTION 
     With reference to the drawings and in particular  FIGS. 1 and 2  initially, an umbrella  1  according to the present invention is shown. Umbrella  1  includes a frame having a shaft  2  with a canopy  3  at or adjacent or proximate to one end and a handle  4  at the opposite end of the shaft. Shaft  2  may be solid or hollow and may be cylindrical or have an alternative cross-sectional shape such as square, hexagonal or octagonal. The frame includes a canopy extending/retracting and tensioning means or mechanism at the canopy end of shaft  2 , the structure of which is described below. 
     As most clearly shown in  FIG. 2 , at or near the canopy end of shaft  2  a rose or circular flange or washer  5  is provided. Washer  5  is axially fixed and non-slidable on shaft  2 . A plurality of ribs or spokes  6  are pivotally connected to and preferably equally radially spaced about washer  5 . Due to the added structural strength provided by the construction of the present invention (as will be evident from the ensuing description), even for large “golfing”-type umbrellas, no more than six ribs  6 , 7  need be provided about washer  5  although more than six ribs may be provided. 
     Each rib comprises an inner rod  6  extending between washer  5  and a force spreading means or spreader  8  (not visible in  FIGS. 1 and 2  but explained below with reference to  FIGS. 5A to 5E ) which is hidden within pocket means such as individual pockets  9  spread evenly, or spaced corresponding to the spacing of the ribs, about the periphery of the underside of canopy  3 . Each pocket  9  has an opening to allow for the insertion/removal of a spreader  8  but at least the edge of pocket  9  along the periphery of cover  3  is closed to provide a bearing line or surface for each spreader to contact. The pocket openings face the central portion of the canopy so that a spreader may be positioned within the pocket. For example, the opening may be formed as a slit in the pocket with the slit substantially aligned with a rib  6 , 7  and sized to allow entry of a (closed or compressed) spreader  8 . 
     Alternatively, pockets  9  could be replaced by a single pocket extending about the entire periphery of the canopy. Such a pocket could for example simply be formed by sewing a thin strip (for example, a few centimeters wide) to the underside of the canopy around the periphery of the canopy. 
     Each inner rod  6  may be made of a single rod or may comprise a plurality of (for example two) contiguous or abutable but separate rods in touching contact, end to end. In this way, a first inner rod having particular physical properties (such as relative inflexibility) such as a 2 mm diameter steel rod can form the section of inner rod closest to the shaft but a more lightweight and flexible rod material (such as fiberglass) may form the section of inner rod furthest from the shaft where greater bending force is expected. In this way, overall weight can be reduced by selecting a material for the outer rod portion with a lower weight per unit length than the inner rod portion. The two or more sections of inner rod  6  may, for example, be of equal length. 
     An outer tube  7  is provided about and slidable along each inner rod  6  at or near its end furthest from shaft  2 . The inner rods  6  and outer tubes  7  should have a complimentary cross-sectional shape to allow the outer tube  7  to slide along the inner rod  6 . Preferably the inner rod  6  and outer tube  7  are circular in cross-section but other shapes such as square, hexagonal or octagonal could be used. The inner rod is preferably coaxial with outer tube  7 . 
     Each outer tube  7  is provided with a coupling  10 , which may be formed from polycarbonate, and which pivotally receives the outer end of a primary strut  11 . Coupling  10  is preferably positioned on or around each outer tube  7  at a distance from the shaft which is about the same or slightly shorter that the length of a primary strut. For example, if each primary strut had a length of about 26 cm then the coupling  10  could be positioned around 21 cm from the shaft end of the rib, on the outer tube  7  (when the umbrella is in its fully lowered or collapsed state). Although the inner end of each outer tube  7  could coincide with the location of coupling  10 , it is preferred that the outer tube extend inwards beyond the coupling  10  to reduce the length of exposed inner rod  6 . As will be appreciated from the ensuing description, the exposed section of inner rod  6  contacts the canopy  3  and therefore affects the appearance of the erected umbrella&#39;s profile and, from above the canopy, a discontinuity in the canopy&#39;s curve may be visible between outer tube  7  and rod  6 . More importantly however, allowing the inner ends of outer tubes  7  to coincide with the outer ends of primary struts  11  has been found to create a potential pivot point for the ribs  6 , 7  to invert. In comparison, by having a continuous stiffness through this potential pivot point (by extending the outer tube inwards of the outer end of the primary strut) the ribs are less likely to pivot thereby increasing the umbrella&#39;s ability to withstand inversion. The inner ends of outer tubes  7  may be provided with end caps (as shown in the drawings) to resist the inner ends of the tubes catching on the canopy fabric as they slide over it. The end caps will of course require a central hole to allow for passage of the inner rod therethrough. 
     It may also be desirable to cover the exposed inner portions of the inner rods  6  with a relatively stiff tube, formed from example 8 mm diameter polycarbonate tubing. The stiff tube could simply be an extension of a moulding coupling the inner rod to washer  5 . The stiff tube would extend outwards sufficiently to always extend beyond the inner end of the outer tube  7  which would be slidable within the stiff tube. It is anticipated that the stiff tube would provide an improvement in the continuity of the curve of the canopy between the shaft and the outer rods. 
     The inner end (that is closest to shaft  2 ) of each primary strut  11  is pivotally connected by a coupling to an annulus  12 C about a primary sliding means or primary slider  12  which is slidable along shaft  2 . Movement of primary slider  12  (either manually or spring assisted in the case of “automatic” umbrellas) up and down shaft  2  causes the umbrella to be erected or collapsed respectively. Conventional locking means such as a spring-loaded shaft protrusion  26  may be provided on the shaft to enable sliding means  12  to be retained in position such that the umbrella may be locked in its erected state. It can be seen that primary slider  12  includes a lower cylindrical user gripping portion  12 A and an upper cylindrical spacing portion  12 B, the significance of which will be explained below. 
     In order to improve the ease with which the umbrella may be erected, a secondary strut  13  is connected between a substantially mid-point of each primary strut  11  and a secondary sliding means or slider  14  (not labelled in  FIG. 1  or  FIG. 2 ) which is slidable on shaft  2  between washer  5  and primary slider  12 . The connection between secondary strut  13  and primary strut  11  allows relative pivotal movement therebetween. In the embodiment shown, a connection ring or tube  15  which may for example be formed from polycarbonate, polypropylene or high density polyethylene is fixed to the primary strut  11  about half way along (more preferably, between about 0.5 and 0.6 of the way along and even more preferably, about 15/26 of the way along) its length and the outer end of secondary strut  13  is forked with both prongs pivotally connected to connection ring  15  by a pin. The connection between secondary strut  13  and secondary slider  14  therefore allows pivotal relative movement therebetween. 
     Each secondary strut  13  may be “U” shaped in cross-section or generally convex to allow its associated primary strut  11  to be accommodated therein when the umbrella is in its collapsed state in order to minimise the volume of the collapsed frame. Cut out portions may also be provided in the secondary struts to accommodate couplings  10  when in the collapsed state. It will be appreciated that secondary struts  13  and secondary slider  14  reduce the effort required by a user in erecting the umbrella as they initiate the outwards sliding of the outer tubes  7 . However, other mechanisms for initiating this translational movement could be equally effective. 
     A biasing means such as spring  23  may be provided about the shaft  2  between washer  5  and secondary slider  14 . Spring  23  assists the operator to avoid “over-shooting” by pushing the primary slider  12  too far during erection of the umbrella but also may assist in avoiding any loose movement of the sliders (that is, the spring will effectively take up any “slack” in the sliders&#39; movement). The spring constant of spring  23  is therefore not required to be very large, especially as the spring must be compressed during erection of the umbrella and it is desired that the user need not exert excessive force to compress the spring. 
     Washer  5 , primary  12  and secondary  14  sliders may all be manufactured from rigid plastics material such as polypropylene, high density polyethylene or polycarbonate. Shaft  2 , primary struts  11 , inner rods  6  and outer tubes  7  may be formed from fibreglass pultrusion or folded/rolled metal. Preferably, inner rods  6  (and to a lesser extent outer tubes  7 ) are manufactured from a flexible or elastically bendable material to allow the canopy to assume a curved shape once erected. As previously mentioned, inner rods  6  may include a less flexible inner portion formed for example from steel rod. Secondary struts  13  may be formed from a rigid plastics material or folded metal. 
     Canopy  3  may be formed from any conventional wind/rain/sun-proof fabric such as canvas or nylon. The dimensions of the canopy are arranged so that the distance from the centre of the canopy to the furthest point within each pocket  9  is substantially equal to the distance from the shaft to the outermost point of a spreader  8 . 
     The operation of the canopy extending/retracting and tensioning mechanism of the umbrella will now be described with reference to  FIGS. 3A to 3E ,  4 A to  4 E,  5 A to  5 E and  6 A to  6 E. 
     With reference firstly to  FIGS. 5A to 5E  it can be seen that each spreader  8  includes first  16  and second  17  legs pivotally connected at a pivot region  22 . In the umbrella&#39;s collapsed state as shown in  FIG. 5A , legs  16  and  17  are positioned in a substantially “V” shaped formation. The outer end of outer tube  7  is held captive (by adhesive or a grub screw for example) within a tube mounting hub  18  having forked legs  19  and  20  bendably extending from the tube mounting hub  18  to their distal ends which pivotally connect to respective legs  16  and  17 . Tube mounting hub  18  includes a central passage through which the outer end of an inner rod  6  is passed before terminating in stopper  21 , the end of which is coterminous or integrally formed with the pivot region  22  between legs  16  and  17 . Stopper  21  is formed as an elongate member having a central longitudinal bore commensurate in diameter with the end of inner rod  6 . The end of inner rod  6  is preferably slidable within stopper  21 . 
     Spreader  8  may be integrally formed from a plastics material such as random copolymer polypropylene with each of the pivotal connections (between pivot  22  and legs  16 ,  17  and between legs  16 ,  17  and legs  19 ,  20 ) formed as living hinges. 
     As the outer end of outer tube  7  slides along inner rod  6  towards the outer end of the rib, it can be seen in  FIGS. 5A to 5E  that legs  16  and  17  are splayed or spread until in  FIG. 5E  the legs form a substantially straight line or a “T” shape with outer tube  7  when outer tube  7  reaches the end of its travel and tube mounting hub  18  contacts stopper  21 . Additional radial outwards movement of outer tube  7  will move the entire spreader outward with respect to inner rod  6  and shaft  2  until restrained by the canopy, thereby tensioning the canopy. In practice, legs  16  and  17  will bend in an arc or substantially “U” shape when acting to tension the canopy from within pockets  9  as the pockets are convex to allow tensioning force from spreader  8  to be smoothly applied to the canopy periphery. As previously mentioned, inner rod  6  slides within stopper  21  and it will be appreciated that in order for the stopper to be retained on the inner rod and for the spreading action illustrated in  FIGS. 5A to 5E  to occur, a force must be applied radially inwardly at pivot region  22  and this is provided by the bearing or contact surface within the canopy pockets  9 . 
     In  FIGS. 3A ,  4 A and  6 A the umbrella is shown in its fully collapsed state with ribs  6 , 7  lying substantially against or adjacent to shaft  2 , canopy  3  removed for improved clarity and legs  16  and  17  of spreader  8  in a closed substantially “V” shaped formation. 
     In  FIGS. 3B ,  4 B and  6 B the primary slider  12  has been moved upwards along shaft  2  to around the mid-point of shaft  2 . It can be seen that the ribs  6 , 7  are being pivoted away from shaft  2  by primary struts  11 . Secondary slider  14  is still some distance away from but being pushed towards end washer  5  by secondary struts  13 . Legs  16  and  17  of spreader  8  have opened slightly when compared to their closed state shown in  FIGS. 3A and 4A . 
     At this point spring  23  has been slightly compressed and is therefore providing some resistance to the upward movement of secondary slider  14 . Ideally, the resistance provided would be sufficient to temporally halt upwards movement of secondary slider  14  however, as previously mentioned, a large spring constant for spring  23  would increase the amount of effort required by the user. Accordingly, in one embodiment of the umbrella which will be described below with reference to  FIGS. 7A to 7D , means are provided for actively ensuring a temporary halt to secondary slider  14  at or around the position shown in  FIGS. 3B ,  4 B and  6 B. 
     In  FIGS. 3C ,  4 C and  6 B secondary slider  14  is in the same position along the shaft as is shown in  FIGS. 3B ,  4 B and  6 B. Primary slider  12  is still being moved upwards towards its upper stop and therefore the ribs  6 , 7  are still rotating out from shaft  2 . However, the inner ends of secondary struts  13  are now effectively fixed in position (because secondary slider  14  is temporarily “fixed”) such that the secondary struts  13  are now limited to pivotal movement about their inner ends. The outer ends of secondary struts  13  therefore act as fulcrums to a substantially mid-point of primary struts  11  such that any further upward movement of primary slider  12  causes primary struts  11  to act as levers about these fulcrum points. As a result a mechanical advantage produces a resultant radial force at the outer ends of the primary struts  11  acting along the ribs  6 . This resultant force acts upon the outer tubes  7  via couplings  10 . It can also be seen that legs  16  and  17  of spreader  8  in  FIGS. 3C and 6C  have opened further than in  FIGS. 3B and 6B . 
     In  FIGS. 3D ,  4 D and  6 D it can be seen that the primary slider  12  has been moved further up shaft  2  towards end washer  5 , secondary slider  14  has still not moved any further upward, ribs  6  have pivoted out further from shaft  2  and outer tubes  7  have been further displaced or slid along their respective inner rod  6 , away from shaft  2 . It can also be seen that legs  16  and  17  of spreader  8  are practically fully splayed so that the canopy (not shown) will be tensioned due to the radial force acting along outer tubes  7 . It will also be noted that this radial force will be transferred to the canopy periphery (via a seam formed in each pocket  9  along the canopy&#39;s perimeter) along a line or load-spreading surface formed by legs  16  and  17  of spreader  8  rather than at a point as in conventional umbrellas. 
     In  FIGS. 3E ,  4 E and  6 E it can be seen that secondary slider  14  has now moved further up shaft  2  and that the spring  23  is further compressed. This is the fully erected state of the frame and primary slider  12  has now caught up to and moved secondary slider  14  into its final position. The frame may be held or locked in this fully erected position by a conventional spring loaded shaft protrusion  26  which is withdrawable into the shaft to allow passage of primary slider  12  in the known way. Protrusion  26  then provides a backstop to downwards movement of primary slider  12  until depressed by a user. 
     The upper cylindrical spacing portion  12 B of primary slider  12  acts to push secondary slider  14  upwards but also to fix the final spacing of the primary and secondary sliders. It can be seen that the secondary slider is positioned at about mid way between the primary slider and end washer  5 . In the fully erect state shown in  FIG. 4E  it will be noted that the secondary strut  13  is substantially parallel with rib  6 ,  7  and that the shaft, primary strut  11  and secondary strut  13  form or approximate an isosceles triangle. It has been found that this resulting construction provides significant structural rigidity. 
     In this fully erected position, any additional upwards force on primary slider  12  is converted into tension in the canopy as the entire spreader  8  attempts to move radially outward, effectively attempting to increase the length of the umbrella&#39;s ribs. Equally, any external force such as a gust of wind acting beneath the canopy will find it difficult to invert (or blow inside-out) the umbrella because to do so would require primary struts  11  to rotate or move upwards which movement is resisted by secondary struts  13 . In this position the periphery of the canopy  3  is tightened radially thereby increasing the strength of the umbrella structure and improving the rain-resistance ability of some canopy materials. Furthermore, because the outer tubes  7  are in compression they are less likely to buckle sideways which is required for the structure to invert. 
     With reference now to  FIGS. 7A to 7D  (note that the mechanism is also visible in  FIGS. 6A to 6E ), one embodiment of means for temporarily restraining upward movement of secondary slider  14  will now be described. It has been found that it is desirable to temporarily restrain the secondary slider before the canopy induces bending in the ribs and thereby increasing the frictional drag on the inner rods  6  through outer tubes  7 . For example, secondary slider  14  could be temporarily restrained at about 10 cm from end washer  5 . 
     In  FIGS. 7A to 7D , only a single primary strut  11  and single secondary strut  13  have been shown so that primary  12  and secondary  14  sliders include cavities which would ordinarily be occupied by ends of further struts.  FIG. 7A  corresponds to  FIGS. 3A ,  4 A and  6 A in which the frame is completely collapsed. A clip  24  is shown extending downwards from the lower surface of secondary slider  14 . The clip  24  is preferably formed from an elastically resilient material such as a spring steel rod and is biased inwards towards shaft  2  so that a hook portion  25  contacts the outer surface of the shaft. Hook portion  25  is substantially “c” shaped although its upper section is substantially flat and a curved or camming section depends downwardly therefrom. 
       FIG. 7B  corresponds to  FIGS. 3B and 3C ,  4 B and  4 C, and  6 B and  6 C. In  FIG. 7B  the hook portion  25  of clip  24  has slid upwards along shaft  2  until it has entered a slot  27 . Due to the inwardly directed bias on clip  24  the hook is pushed into slot  27  and the upper, flat section of the hook catches on the upper edge of the slot, arresting movement of secondary slider  14  (which was moving upwards through the vertical component of force imparted via secondary strut  13  from its connection to primary strut  11  and primary strut  12 ). 
       FIG. 7C  corresponds to  FIGS. 3D ,  4 D and  6 D wherein the upper cylindrical spacer  12  of primary slider  12  reaches the hook portion  25  of clip  24  and through camming action along the downwardly directed curved section of the hook, dislodges the hook portion  25  from slot  27  so that secondary slider  14  is once again freely movable upwards on the shaft. Once the hook is dislodged the outer tubes  7  will have been radially displaced along their inner rods  6  before additional frictional drag is introduced by curved outer tubes/inner rods. 
       FIG. 7D  corresponds to  FIGS. 3E ,  4 E and  6 E, wherein the umbrella is fully erected and the upper cylindrical spacer  12 B has slid completely beneath clip  24  and is bearing against (and has moved upwardly) secondary slider  14 . 
     During collapsing of the umbrella, the lower curved surface of hook portion  25  (which projects forward, past the axis of the clip) rides along the surface of the shaft and re-enters the slot  27  but is not trapped therein because the end of the hook will always project out of the slot. The lower curved surface of the hook then contacts the lower edge of the slot and emerges from the slot to continue its slide down along the shaft. 
     The spring loaded shaft protrusion  26  is also utilised during collapsing of the umbrella to stop the downwards movement of the secondary slider  14  which thereby initiates the retraction of the outer ribs along the inner rods  6 . For this purpose the upper edge of protrusion  26  may be provided with a flat portion parallel to the lower surface of secondary slider  14 . This allows secondary slider  14  to rest against protrusion  26  without any component of force being applied to the protrusion in a direction which would initiate retraction of the protrusion (that is, no force is directed towards the shaft). In contrast, the lower surface of protrusion  26  is preferably curved or cam-shaped to allow the primary slider  12  to pass the protrusion during umbrella erection, thereby retracting it within shaft  12 . 
     As previously mentioned, canopy  3  is primarily attached to the umbrella frame by virtue of spreaders  8  being located within purpose-built pockets  9  provided at equally spaced locations around the periphery of the canopy. Additionally, the canopy could be fixed to the end of shaft  2  (to washer  5  for example) and/or connected to ribs  6 , 7  at some point along their length by for example ties (not shown) sewn into the underside of the canopy which may be tied or connected about each of the ribs. A preferred connection system could incorporate VELCRO® releasable fasteners comprising loops and hooks provided on respective opposing tie surfaces to allow the canopy to be easily removed should it be necessary or convenient to do so. Accordingly, a user could regularly replace or select a particular canopy for use with the umbrella frame according to the present invention which could easily be fitted or removed by the user without tools. 
     It will be appreciated that the present invention is applicable to rain umbrellas, sun or beach umbrellas and parasols and that the invention is equally applicable to collapsible shaft umbrellas or fixed shaft umbrellas. It should also be noted that aspects of the invention could be incorporated into other umbrella-like devices in which support ribs or arms are generally radially attached to a central post or pole such as in collapsible rotary clothes lines, tents or awnings/sun shades. In the case of collapsible rotary clothes line it would of course not be necessary to incorporate features such as the spreader at the end of each rib. 
     Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof.