Umbrella

An umbrella (1) in which the canopy is supported, tensioned and retained on a frame without any external points. The ends of conventional ribs (6,7) are provided with force spreading components (8) which are located within pockets (9) at the periphery of the umbrella canopy (3). As the umbrella is erected, the force spreading components open to provide a surface which pushes outwardly against a bearing surface formed between a pocket and the canopy, which “spread” outwards. The spreading of the components (8) is initiated by the radially outward movement of slidable tubes (7) upon inner rods (6) attached at their inner ends to the shaft (2) of the umbrella. Inner rods (6) and outer tubes (7) together form the ribs or spokes of the umbrella which are supported and raised/lowered by primary struts (11) connected between the ribs and a primary shaft slider (12). Outward sliding movement of the outer tubes (7) over the inner rods (6) is assisted by secondary struts (13) which connect a secondary shaft slider (14) (positioned between the primary shaft slider (12) and the canopy end of the shaft) and a respective primary strut (11).

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'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'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'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.

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'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'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.

BEST MODES FOR CARRYING OUT THE INVENTION

With reference to the drawings and in particularFIGS. 1 and 2initially, an umbrella1according to the present invention is shown. Umbrella1includes a frame having a shaft2with a canopy3at or adjacent or proximate to one end and a handle4at the opposite end of the shaft. Shaft2may 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 shaft2, the structure of which is described below.

As most clearly shown inFIG. 2, at or near the canopy end of shaft2a rose or circular flange or washer5is provided. Washer5is axially fixed and non-slidable on shaft2. A plurality of ribs or spokes6are pivotally connected to and preferably equally radially spaced about washer5. 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 ribs6,7need be provided about washer5although more than six ribs may be provided.

Each rib comprises an inner rod6extending between washer5and a force spreading means or spreader8(not visible inFIGS. 1 and 2but explained below with reference toFIGS. 5A to 5E) which is hidden within pocket means such as individual pockets9spread evenly, or spaced corresponding to the spacing of the ribs, about the periphery of the underside of canopy3. Each pocket9has an opening to allow for the insertion/removal of a spreader8but at least the edge of pocket9along the periphery of cover3is 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 rib6,7and sized to allow entry of a (closed or compressed) spreader8.

Alternatively, pockets9could 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 rod6may 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 rod6may, for example, be of equal length.

An outer tube7is provided about and slidable along each inner rod6at or near its end furthest from shaft2. The inner rods6and outer tubes7should have a complimentary cross-sectional shape to allow the outer tube7to slide along the inner rod6. Preferably the inner rod6and outer tube7are circular in cross-section but other shapes such as square, hexagonal or octagonal could be used. The inner rod is preferably coaxial with outer tube7.

Each outer tube7is provided with a coupling10, which may be formed from polycarbonate, and which pivotally receives the outer end of a primary strut11. Coupling10is preferably positioned on or around each outer tube7at 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 coupling10could be positioned around 21 cm from the shaft end of the rib, on the outer tube7(when the umbrella is in its fully lowered or collapsed state). Although the inner end of each outer tube7could coincide with the location of coupling10, it is preferred that the outer tube extend inwards beyond the coupling10to reduce the length of exposed inner rod6. As will be appreciated from the ensuing description, the exposed section of inner rod6contacts the canopy3and therefore affects the appearance of the erected umbrella's profile and, from above the canopy, a discontinuity in the canopy's curve may be visible between outer tube7and rod6. More importantly however, allowing the inner ends of outer tubes7to coincide with the outer ends of primary struts11has been found to create a potential pivot point for the ribs6,7to 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's ability to withstand inversion. The inner ends of outer tubes7may 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 rods6with 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 washer5. The stiff tube would extend outwards sufficiently to always extend beyond the inner end of the outer tube7which 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 shaft2) of each primary strut11is pivotally connected by a coupling to an annulus12C about a primary sliding means or primary slider12which is slidable along shaft2. Movement of primary slider12(either manually or spring assisted in the case of “automatic” umbrellas) up and down shaft2causes the umbrella to be erected or collapsed respectively. Conventional locking means such as a spring-loaded shaft protrusion26may be provided on the shaft to enable sliding means12to be retained in position such that the umbrella may be locked in its erected state. It can be seen that primary slider12includes a lower cylindrical user gripping portion12A and an upper cylindrical spacing portion12B, the significance of which will be explained below.

In order to improve the ease with which the umbrella may be erected, a secondary strut13is connected between a substantially mid-point of each primary strut11and a secondary sliding means or slider14(not labelled inFIG. 1orFIG. 2) which is slidable on shaft2between washer5and primary slider12. The connection between secondary strut13and primary strut11allows relative pivotal movement therebetween. In the embodiment shown, a connection ring or tube15which may for example be formed from polycarbonate, polypropylene or high density polyethylene is fixed to the primary strut11about 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 strut13is forked with both prongs pivotally connected to connection ring15by a pin. The connection between secondary strut13and secondary slider14therefore allows pivotal relative movement therebetween.

Each secondary strut13may be “U” shaped in cross-section or generally convex to allow its associated primary strut11to 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 couplings10when in the collapsed state. It will be appreciated that secondary struts13and secondary slider14reduce the effort required by a user in erecting the umbrella as they initiate the outwards sliding of the outer tubes7. However, other mechanisms for initiating this translational movement could be equally effective.

A biasing means such as spring23may be provided about the shaft2between washer5and secondary slider14. Spring23assists the operator to avoid “over-shooting” by pushing the primary slider12too 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' movement). The spring constant of spring23is 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.

Washer5, primary12and secondary14sliders may all be manufactured from rigid plastics material such as polypropylene, high density polyethylene or polycarbonate. Shaft2, primary struts11, inner rods6and outer tubes7may be formed from fibreglass pultrusion or folded/rolled metal. Preferably, inner rods6(and to a lesser extent outer tubes7) are manufactured from a flexible or elastically bendable material to allow the canopy to assume a curved shape once erected. As previously mentioned, inner rods6may include a less flexible inner portion formed for example from steel rod. Secondary struts13may be formed from a rigid plastics material or folded metal.

Canopy3may 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 pocket9is substantially equal to the distance from the shaft to the outermost point of a spreader8.

The operation of the canopy extending/retracting and tensioning mechanism of the umbrella will now be described with reference toFIGS. 3A to 3E,4A to4E,5A to5E and6A to6E.

With reference firstly toFIGS. 5A to 5Eit can be seen that each spreader8includes first16and second17legs pivotally connected at a pivot region22. In the umbrella's collapsed state as shown inFIG. 5A, legs16and17are positioned in a substantially “V” shaped formation. The outer end of outer tube7is held captive (by adhesive or a grub screw for example) within a tube mounting hub18having forked legs19and20bendably extending from the tube mounting hub18to their distal ends which pivotally connect to respective legs16and17. Tube mounting hub18includes a central passage through which the outer end of an inner rod6is passed before terminating in stopper21, the end of which is coterminous or integrally formed with the pivot region22between legs16and17. Stopper21is formed as an elongate member having a central longitudinal bore commensurate in diameter with the end of inner rod6. The end of inner rod6is preferably slidable within stopper21.

Spreader8may be integrally formed from a plastics material such as random copolymer polypropylene with each of the pivotal connections (between pivot22and legs16,17and between legs16,17and legs19,20) formed as living hinges.

As the outer end of outer tube7slides along inner rod6towards the outer end of the rib, it can be seen inFIGS. 5A to 5Ethat legs16and17are splayed or spread until inFIG. 5Ethe legs form a substantially straight line or a “T” shape with outer tube7when outer tube7reaches the end of its travel and tube mounting hub18contacts stopper21. Additional radial outwards movement of outer tube7will move the entire spreader outward with respect to inner rod6and shaft2until restrained by the canopy, thereby tensioning the canopy. In practice, legs16and17will bend in an arc or substantially “U” shape when acting to tension the canopy from within pockets9as the pockets are convex to allow tensioning force from spreader8to be smoothly applied to the canopy periphery. As previously mentioned, inner rod6slides within stopper21and it will be appreciated that in order for the stopper to be retained on the inner rod and for the spreading action illustrated inFIGS. 5A to 5Eto occur, a force must be applied radially inwardly at pivot region22and this is provided by the bearing or contact surface within the canopy pockets9.

InFIGS. 3A,4A and6A the umbrella is shown in its fully collapsed state with ribs6,7lying substantially against or adjacent to shaft2, canopy3removed for improved clarity and legs16and17of spreader8in a closed substantially “V” shaped formation.

InFIGS. 3B,4B and6B the primary slider12has been moved upwards along shaft2to around the mid-point of shaft2. It can be seen that the ribs6,7are being pivoted away from shaft2by primary struts11. Secondary slider14is still some distance away from but being pushed towards end washer5by secondary struts13. Legs16and17of spreader8have opened slightly when compared to their closed state shown inFIGS. 3A and 4A.

At this point spring23has been slightly compressed and is therefore providing some resistance to the upward movement of secondary slider14. Ideally, the resistance provided would be sufficient to temporally halt upwards movement of secondary slider14however, as previously mentioned, a large spring constant for spring23would increase the amount of effort required by the user. Accordingly, in one embodiment of the umbrella which will be described below with reference toFIGS. 7A to 7D, means are provided for actively ensuring a temporary halt to secondary slider14at or around the position shown inFIGS. 3B,4B and6B.

InFIGS. 3C,4C and6B secondary slider14is in the same position along the shaft as is shown inFIGS. 3B,4B and6B. Primary slider12is still being moved upwards towards its upper stop and therefore the ribs6,7are still rotating out from shaft2. However, the inner ends of secondary struts13are now effectively fixed in position (because secondary slider14is temporarily “fixed”) such that the secondary struts13are now limited to pivotal movement about their inner ends. The outer ends of secondary struts13therefore act as fulcrums to a substantially mid-point of primary struts11such that any further upward movement of primary slider12causes primary struts11to 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 struts11acting along the ribs6. This resultant force acts upon the outer tubes7via couplings10. It can also be seen that legs16and17of spreader8inFIGS. 3C and 6Chave opened further than inFIGS. 3B and 6B.

InFIGS. 3D,4D and6D it can be seen that the primary slider12has been moved further up shaft2towards end washer5, secondary slider14has still not moved any further upward, ribs6have pivoted out further from shaft2and outer tubes7have been further displaced or slid along their respective inner rod6, away from shaft2. It can also be seen that legs16and17of spreader8are practically fully splayed so that the canopy (not shown) will be tensioned due to the radial force acting along outer tubes7. It will also be noted that this radial force will be transferred to the canopy periphery (via a seam formed in each pocket9along the canopy's perimeter) along a line or load-spreading surface formed by legs16and17of spreader8rather than at a point as in conventional umbrellas.

InFIGS. 3E,4E and6E it can be seen that secondary slider14has now moved further up shaft2and that the spring23is further compressed. This is the fully erected state of the frame and primary slider12has now caught up to and moved secondary slider14into its final position. The frame may be held or locked in this fully erected position by a conventional spring loaded shaft protrusion26which is withdrawable into the shaft to allow passage of primary slider12in the known way. Protrusion26then provides a backstop to downwards movement of primary slider12until depressed by a user.

The upper cylindrical spacing portion12B of primary slider12acts to push secondary slider14upwards 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 washer5. In the fully erect state shown inFIG. 4Eit will be noted that the secondary strut13is substantially parallel with rib6,7and that the shaft, primary strut11and secondary strut13form 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 slider12is converted into tension in the canopy as the entire spreader8attempts to move radially outward, effectively attempting to increase the length of the umbrella'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 struts11to rotate or move upwards which movement is resisted by secondary struts13. In this position the periphery of the canopy3is tightened radially thereby increasing the strength of the umbrella structure and improving the rain-resistance ability of some canopy materials. Furthermore, because the outer tubes7are in compression they are less likely to buckle sideways which is required for the structure to invert.

With reference now toFIGS. 7A to 7D(note that the mechanism is also visible inFIGS. 6A to 6E), one embodiment of means for temporarily restraining upward movement of secondary slider14will 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 rods6through outer tubes7. For example, secondary slider14could be temporarily restrained at about 10 cm from end washer5.

InFIGS. 7A to 7D, only a single primary strut11and single secondary strut13have been shown so that primary12and secondary14sliders include cavities which would ordinarily be occupied by ends of further struts.FIG. 7Acorresponds toFIGS. 3A,4A and6A in which the frame is completely collapsed. A clip24is shown extending downwards from the lower surface of secondary slider14. The clip24is preferably formed from an elastically resilient material such as a spring steel rod and is biased inwards towards shaft2so that a hook portion25contacts the outer surface of the shaft. Hook portion25is substantially “c” shaped although its upper section is substantially flat and a curved or camming section depends downwardly therefrom.

FIG. 7Bcorresponds toFIGS. 3B and 3C,4B and4C, and6B and6C. InFIG. 7Bthe hook portion25of clip24has slid upwards along shaft2until it has entered a slot27. Due to the inwardly directed bias on clip24the hook is pushed into slot27and the upper, flat section of the hook catches on the upper edge of the slot, arresting movement of secondary slider14(which was moving upwards through the vertical component of force imparted via secondary strut13from its connection to primary strut11and primary strut12).

FIG. 7Ccorresponds toFIGS. 3D,4D and6D wherein the upper cylindrical spacer12of primary slider12reaches the hook portion25of clip24and through camming action along the downwardly directed curved section of the hook, dislodges the hook portion25from slot27so that secondary slider14is once again freely movable upwards on the shaft. Once the hook is dislodged the outer tubes7will have been radially displaced along their inner rods6before additional frictional drag is introduced by curved outer tubes/inner rods.

FIG. 7Dcorresponds toFIGS. 3E,4E and6E, wherein the umbrella is fully erected and the upper cylindrical spacer12B has slid completely beneath clip24and is bearing against (and has moved upwardly) secondary slider14.

During collapsing of the umbrella, the lower curved surface of hook portion25(which projects forward, past the axis of the clip) rides along the surface of the shaft and re-enters the slot27but 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 protrusion26is also utilised during collapsing of the umbrella to stop the downwards movement of the secondary slider14which thereby initiates the retraction of the outer ribs along the inner rods6. For this purpose the upper edge of protrusion26may be provided with a flat portion parallel to the lower surface of secondary slider14. This allows secondary slider14to rest against protrusion26without 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 protrusion26is preferably curved or cam-shaped to allow the primary slider12to pass the protrusion during umbrella erection, thereby retracting it within shaft12.

As previously mentioned, canopy3is primarily attached to the umbrella frame by virtue of spreaders8being located within purpose-built pockets9provided at equally spaced locations around the periphery of the canopy. Additionally, the canopy could be fixed to the end of shaft2(to washer5for example) and/or connected to ribs6,7at 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.