WO2007093871A1

WO2007093871A1 - Collapsible frames

Info

Publication number: WO2007093871A1
Application number: PCT/IB2007/000316
Authority: WO
Inventors: Ritchie James Buttle
Original assignee: Ritchie James Buttle
Priority date: 2006-02-13
Filing date: 2007-02-12
Publication date: 2007-08-23
Also published as: ZA200807854B

Abstract

A collapsible frame is provided comprising at least two primary composite frames (10) of generally polygonal shape in the erected condition and each of which is composed of a plurality of crossed pairs of struts (12, 19) pivotally attached to each other by means of a median pivot (15, 20) in a central region of the length thereof with the ends of the struts being pivotally attached to a strut of a contiguous pair by means of inner and outer pivots (13, 14) to form a lazy tong construction. The median pivots connecting the struts of at least two adjacent pairs are inner median pivots (15) (as defined) such that the extended primary composite frame member adopts a polygonal shape in an erected terminal condition. The primary composite frames are connected by pivotally attached pairs of crossed connecting struts (11) extending in the longitudinal direction so as to extend and retract in lazy tong fashion in unison with the struts of the primary composite frame members but in a plane at generally right angles thereto. The entire assembly is configured, such that in an erected condition the struts of the comer defining struts that are connected by the inner pivot (13) extend at an angle to each other of at least 240 degrees with respect to an angle of from 5 to 15 degrees at which they extend to each other in the collapsed terminal condition of the collapsible frame.

Description

COLLAPSIBLE FRAMES

FIELD OF THE INVENTION

This invention relates to collapsible frames that collapse in three directions whilst the component frame members remain connected to each other thereby avoiding any appreciable dismantling of the frame for transport and storage purposes.

The invention also relates to structures that utilise such collapsible frames. Such structures may be used to form a support for one or more panels of flexible sheet material in order to exhibit advertising displays, typically in the form of a banner or the like; to form small shelters in which the panels define one or more side walls, a roof, sun shield, barrier or other cover. Preferably, but not necessarily, the panels of flexible sheet material may remain attached to the frame when it is collapsed so that the structure is capable of rapid deployment for use, and collapsing for transport and storage purposes.

Structures of particular interest are those that are required for intermittent use, for example, at sports or other public events that are convened from time to time in different locations. Such structures are preferably easily erected and collapsed by a minimum number of persons in order that they can be easily and swiftly deployed for use when necessary and similarly, easily and swiftly collapsed for transport and storage purposes.

BACKGROUND TO THE INVENTION

Numerous different collapsible frames and structures have been proposed and are available on the market. Many of them are costly and relatively difficult to erect and collapse. Many of them employ a collapsible frame that involves at least partial removal of the flexible sheet panels; at least partial dismantling of multiple frame members; or both. Some structures have one or, typically, three, four, or more supporting uprights that may be telescopically extensible, foldable, or not collapsible at all. Such uprights are often difficult to handle, and to transport and store.

Some structures that do not require dismantling do not collapse in three directions (other than structures having the general configuration of an umbrella). One full- scale dimension such a structure remains in the extended condition and the collapsed structure is often still excessively large for many applications. In particular, such collapsed structures may be too large to be stored in the luggage compartment or on the back seat of a motor car.

Of particular interest to the present invention is collapsible frames composed of a series of crossed pairs of levers or struts (hereinafter referred to as struts) wherein the members of each pair are pivotally attached to each other in a central region, but somewhat off-centre in the lengthwise direction, with each end of a strut being pivotally attached to a member of the next contiguous pivotally connected pair to form a criss-crossed arrangement referred to herein as a lazy tong construction. However, unlike in the case of a conventional lazy tong arrangement in which the members of each pair are pivotally attached to each other at their centres, with the resultant extended frame being straight, the off-centre pivot results in composite frames that are of generally curved arch shape in the erected condition.

Examples of these that collapse only in the planes of the arch shaped erected frame are described in prior US patents 3,559,353 to Partridge; Re31 ,565 to Beaulieu; and 3,375,624 to Mikulin. Examples of this type of frame that collapses in three directions are described in US patent 5,761 ,871 to Atake and published US patent application number US2003/00782845.

In this instance, longitudinal lazy tong struts are employed to space the arch shaped frames apart and the longitudinal lazy tongs struts are pivoted together centrally of their length. The result is a tunnel shaped frame of constant cross- section. The disclosure of the latter two prior publications is specifically included herein by reference. It is to be noted that, with this construction, the inner ends of the struts of one crossed pair rotate relative to the pivotally attached inner end of the associated strut of an adjacent crossed pair from a collapsed terminal position in which the pivotally attached struts extend at about 5 to 15 degrees relative to each other to an erected terminal position in which they have rotated through an angle of about 120 to 160 degrees corresponding to the extended condition of the particular pair of crossed struts.

This type of frame assembly, typically such as that disclosed in the patent application referred to above, operate effectively in particular applications. However, none of the proposals disclosed enables walls or banners to be supported by them in a generally flat condition, a condition in which they are most effectively viewed when used for promotional purposes. The reason is the generally curved arch shape of the composite frame members in the erected condition. Thus, for example, these proposals do not lend themselves to constructing a frame having a generally A-frame configuration, or an erected frame of polygonal, in particular square or triangular shape in cross-section. In addition, there is a danger, in the latter proposals that a flexible cover panel can become jammed between the struts as they pivot towards each other in order to move to positions corresponding to the collapsed condition of the frame.

OBJECT OF THE INVENTION

It is, accordingly, one object of this invention to provide a collapsible frame of the general lazy tong type indicated above that overcomes certain disadvantages of the prior art frames, at least to some extent.

DEFINITIONS

In order to facilitate further description and definition of the present invention the following terms are intended to have the following meanings: -

"outer pivot" means a pivot that interconnects the ends of two struts of two connected crossed pairs thereof wherein that pivot is located on the outside of the composite frame in the erected condition; "inner pivot" means a pivot that interconnects the ends of two struts of two connected crossed pairs thereof that is to be located on the inside of the composite frame in the erected condition;

"outer median pivot" means a pivot that interconnects the two struts of a crossed pair thereof in the instance that the median pivot is closer to its directly associated outer pivot than it is to its associated inner pivot; and,

"inner median pivot" means a pivot that interconnects the two struts of a crossed pair thereof in the instance that the median pivot is closer to its directly associated inner pivot than it is to its associated outer pivot;

"transverse" as regards direction with respect to the erected collapsible frame means the direction or plane in which the primary composite frames extend and collapse; and,

"longitudinal" as regards direction with respect to the erected collapsible frame means the direction in which the primary composite frames are spaced apart with respect to each other.

SUMMARY OF THE INVENTION

In accordance with one aspect of this invention there is provided a collapsible frame comprising at least two primary composite frames of operatively generally polygonal shape in the erected condition and each of which is composed of a plurality of crossed pairs of struts wherein the struts of each pair are pivotally attached to each other by means of a median pivot in a central region of the length thereof with operatively inner and outer ends of the struts (other than those forming terminal ends of the composite frame member) being pivotally attached to a strut of a contiguous pivotally connected pair by means of inner and outer pivots to form a lazy tong construction and wherein the median pivots connecting the struts of at least two adjacent pairs thereof are inner median pivots (as defined) such that the extended primary composite frame member adopts said operatively polygonal shape in an erected terminal condition, and wherein the inner and outer pivots of each primary composite frame are provided with formations defining nodes to which inner and outer ends of a pair of crossed connecting struts extending in the longitudinal direction are pivotally attached by means of pivots having their axes at generally right angles to those of the said inner and outer pivots of the primary composite frame member and wherein the connecting struts of a pair thereof are pivotally attached to each other in a central region of their length so that the connecting struts extend and retract in lazy tong fashion in unison with the struts of the primary composite frame members but in a plane at generally right angles thereto as the collapsible frame is moved from a collapsed terminal condition to an erected terminal condition and vice versa, the collapsible frame being characterised in that said two adjacent pairs of pivotally connected struts constitute comer defining struts in the erected condition of the collapsible frame and the median pivots are positioned, and the entire assembly is configured, such that in an erected terminal condition of the frame the struts of the corner defining struts that are connected by the inner pivot extend at an angle to each other of at least 240 degrees with respect to an angle of from 5 to 15 degrees at which they extend to each other in the collapsed terminal condition of the collapsible frame.

In other words, the struts of the corner defining pairs thereof that are connected by the inner pivot rotate, during the erection procedure, through an angle of in excess of 180 degrees thereby enabling the general planes of the corner defining struts to extend at an angle of less than about 120 degrees to each other (corresponding to relative pivotal movement of the struts connected by the inner pivot through an angle of about 250 degrees), typically at about 90 degrees to each other, or in the case of a triangular or A-frame type of arrangement, at only about 30 to 50 degrees to each other (corresponding to relative pivotal movement through an angle of about 300 to 320 degrees). These angles of movement are quite different from those associated with the known arrangement in which the struts connected by the relevant inner pivot move angularly relative to each other through an angle of only about 120 to about 160 degrees. It is a particular feature of the invention that any additional crossed pairs of struts connected directly to one of said two corner defining pairs of struts be interconnected by outer median pivots (as herein defined) and any additional crossed pairs of struts connected to those be interconnected by inner median pivots, and so on, alternately, so that the plane of an expanded portion of the frame extending from a corner is generally flat. It will be understood that in the case of an A-frame type of structure only one corner is provided in which instance the same number of additional crossed pairs of struts may be added to each of the corner defining pairs thereof. Most conveniently, a low height A-frame structure may be provided using only the two pairs of corner defining struts and any larger version would conveniently use one or more additional pairs of crossed struts associated with each of the corner defining pairs of struts.

Of course, the length of the erected frame will simply be determined by the number of primary composite frames that are employed and the consequent number of connecting struts employed to hold them in spaced relationship in the longitudinal direction of the erected terminal condition.

Further features of this aspect of the invention provide for each of said nodes to assume the form of a right angled bracket having one flange attached to the inner or outer end of the associated strut by means of the inner or outer pivot, as the case may be, and the other flange of the bracket pivotally attached to the associated end of the connecting strut; for the free end of an operatively ground engaging strut to be extended beyond the pivot and provided with a ground engaging foot; for the inner and outer pivots connecting the corner defining pairs of crossed struts to be provided, in appropriate instances, with handgrips whereby they can be manipulated to erect the collapsible frame; for the free ends of operatively ground engaging struts to be provided, in appropriate instances, with handgrips for lifting and manipulating the frame from its erected condition to its collapsed condition; for flexible cover panels to be releasably or permanently attached to the operatively outer ends of the struts, the operatively inner ends of the struts, or both, conveniently, and preferably, by way of separate dedicated supports; and for means to be provided for releasably fixing or arresting the positions of the pivotally inter-connected struts in their terminal operative positions.. Typically all corresponding inner and outer nodes of the primary composite frame members are inter-connected by means of pairs of connecting struts with appropriate pairs of connecting struts being omitted in order to provide any required access apertures or to reduce the cost when the relevant strength is not required.

The invention thus provides, in particular, collapsible frames of A-frame style of display structures; habitable enclosures that, with flexible side walls, a flexible roof, or both, can be used to form a collapsible gazebo, kiosk, changing booth, or other temporary habitable facility. It is to be noted that, in the operative orientation of the erected frame, the primary composite frames are not necessarily orientated in a generally vertical plane and could be orientated in a generally horizontal plane in which instance the length defined above extends in a generally vertical direction.

In accordance with a second aspect of the invention there is provided a support for a cover for a collapsible frame as defined above the support comprising a rigidly flexible web having an anchorage formation at each end thereof adapted for attachment to an end region of a strut of a frame as defined above with the web adopting the operative configuration of a flexible arch over the outer ends of the pivotally attached struts.

Further features of this aspect of the invention provide for the anchorage formation to include perforated flange formations adapted to receive the associated outer pivot passing therethrough; and for the support to be cut from a suitable sheet material, in particular, a suitable rigidly flexible plastics material.

In accordance with a third aspect of the invention there is provided a deflector of elongate shape and made of generally rigidly flexible material, the deflector having anchorage formations at each end thereof adapted for attachment to the side edge of each of two struts of a pivotally connected crossed pair thereof and elongate slots for accommodating the struts with a strut passing through the slot with the deflector being directed towards the outer ends of the slats and the anchorage formations attached to the inner edge thereof such that the central region of the deflector is directed towards the outside of the frame in both the collapsed and erected terminal positions of the frame. The invention also provides a collapsible frame as defined above having installed in association with each of the outer pivots thereof a support as defined above, or a deflector as defined above, or both.

In order that the above and other features of the invention may be more fully understood various embodiments of the invention will now be described with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:-

Figure 1 is a front elevation taken of a nested, collapsed frame according to the prior art;

Figure 2 is the same view as Figure 1 and shows a primary composite frame member in a preliminary stage of extension during erection of the frame;

Figure 3 shows about one half of the primary composite frame member in a fully erected condition;

Figure 4 is the same view as Figure 1 but showing a simple embodiment of the present invention;

Figure 5 is a side elevation of the collapsed frame illustrated in Figure 4 showing the interconnection of the primary composite frames by means of crossed pairs of connecting struts;

Figure 6 is the same as Figure 4 showing the primary composite frame in a preliminary stage of erection;

Figure 7 is the same as Figure 4 showing the primary composite frame in an advanced degree of erection; Figure 8 is the same as Figure 4 showing the primary composite frame in the fully erected condition;

Figure 9 is a side elevation corresponding to Figure 5 showing two sets of connecting struts holding three primary composite frames in spaced relationship in the longitudinal direction;

Figure 10 is a plan view showing the pivotal connections of the top ends of two longitudinally spaced pairs of struts of two primary composite frames and an interconnecting crossed pair of connecting struts;

Figure 11 is a plan view of a diecut support unit for a cover for the frame of Figures 4 to 10;

Figure 12 is an elevation of the support of Figure 11 in the installed condition;

Figure 13 is a side elevation of the installed support with the associated struts making an obtuse angle of each other;

Figure 14 is a similar side elevation with the associated struts in their collapsed condition and extending generally parallel to each other;

Figure 15 is a plan view of a diecut deflector blank for installation on the frame illustrated in Figures 4 to 9;

Figure 16 illustrates the deflector installed on a pair of struts that make an obtuse angle with each other corresponding to the erected terminal position of the frame;

Figure 17 is similar to Figure 16 with the pair of struts making an acute angle with each other corresponding generally to the collapsed terminal condition of the frame; Figure 18 is a front elevation corresponding to Figure 4 and showing two additional pairs of crossed struts on each side of the two corner defining pairs thereof;

Figure 19 is a front elevation showing the fully erected terminal condition of the frame illustrated in Figure 18;

Figure 20 is a is a plan view of one form of the second variation of frame according to the invention;

Figure 21 is a schematic isometric view of the erected frame illustrated in Figure 20 and showing a broken away cover in position to enclose the frame; and,

Figures 22 and 23 are plan views similar to Figure 20 but illustrating two different polygonal shapes of erected frame.

DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS

Firstly, referring to Figures 1 to 3 of the drawings, a prior art collapsible, generally tunnel shaped frame structure is based on primary composite frame members, indicated by numeral (1), each of which is composed of an identical arrangement of crossed pairs of struts (2) with each pair being interconnected in a central region by means of a roughly central median pivot (3). It is to be noted that, in the drawings, for purposes of clarity, the struts that are located in a forward plane are shown in solid lines whilst those in a rearward plane are shown in dotted lines.

The free ends (4) of each of the struts (other than the free terminal ends (4a)) are connected to corresponding ends of the struts of an adjacent pair by means of inner pivots (5) and outer pivots (6), as the case may be, in order to form the well-known lazy tong configuration. However, the central pivots are located slightly closer to the inner pivots than to the outer pivots so that, upon extension of the lazy tong structure from the condition illustrated in Figure 1 , the inner pivots move apart by a somewhat smaller distance than do the outer pivots. In consequence of this, the entire extended composite frame member assumes an arched configuration, as illustrated in Figure 3.

During the erection procedure, it will be seen that the inner ends of the struts connected by the inner pivots move angularly relative to each other from a position in which they make a small acute angle "α" with each other to one in which they make an obtuse angle "β" with each other. These struts therefore rotate about the inner pivot through an angle of appreciably less than 180 degrees.

A plurality of primary composite frames of this nature that extend in the transverse direction are interconnected with crossed pairs of connecting struts (7) that extend in the longitudinal direction. The pairs of connecting struts are pivotally attached to the sites of the inner and outer pivots so that the spacing between adjacent primary composite frames increases as the frame is moved to its erected terminal condition illustrated in Figure 3.

Turning now to the simplest embodiment of the present invention, and with particular reference to Figures 4 to 10, four primary composite frames, generally indicated by numeral (10), are interconnected by three sets of crossed centrally pivoted connector struts (11). Each primary composite frame is, in this instance, composed of only two crossed pairs of struts, being corner defining struts (12). In this format the structure is particularly aimed at providing a low height support structure for an advertising banner or other display.

The ends of the two pairs of corner defining struts (12) are connected together at an inner pivot (13) and outer pivot (14) whilst the struts of each of the crossed pairs thereof are interconnected by inner median pivots (15). In this particular embodiment of the invention the distance between the inner and outer pivots is about 850 millimetres and the distance of the inner median pivot from the inner pivot is about 370 millimetres thus representing about 44 percent of the distance between the inner and outer pivots. The length of the struts can obviously be chosen according to requirements. As a general rule, it is envisaged that a length of strut of form about 800 mm (about 31 inches) to 1200 mm (about 47 inches) will be appropriate with a maximum length of about 1 m (about 39 inches) being envisaged. A collapsed frame made up of struts of such a length should be capable of being accommodated in almost any conventional motor car luggage compartment.

In contradistinction to the offset of the median pivots, the crossed pairs of connecting struts (11) are connected together by pivots (16) located centrally of their length. The free ends of the crossed pairs of connecting struts (11) are each pivotally attached to one limb of a right angled bracket (17) by means of pivots (18) having their axes at right angles to those of the inner and outer pivots with the other limb of each of the brackets being attached to the inner or outer pivot (14) or (13) itself, as the case may be. This construction is shown most clearly in Figure 10. In the instance of the terminal or free ends of the corner defining struts (12) the brackets are attached to the corner defining struts at similar positions by means of pivots indicated by numerals (14a) and (13a) as no other strut is pivotally attached thereto. The distance between the pivots (18) at the opposite ends of a connecting strut is the same as that of the corner defining struts of the primary composite frames namely, in the specific example given, 850 millimetres.

It is to be noted that, if increased height with respect to the width of the A-frame is required, this can be achieved by reversing a first pair of additional crossed struts

(19) (see Figures 18 and 19) in so far as the struts thereof are interconnected by an outer median pivot (20) and a subsequent pair of additional crossed struts (21) are interconnected by an inner median pivot (22). More alternate pairs of struts may be added in a similar manner. By alternating the arrangement of pairs of struts in this manner, identical pairs of pivoted struts can be used to create effectively straight sections to the erected frame assembly simply by alternating from inner to outer median pivots.

In order to impart desirable handling properties to the collapsible structure, the struts are preferably made of a lightweight material such as glass fibre reinforced resins and aluminium or titanium based extrusions, most appropriately, tubular extrusions. However, any other material can be employed to manufacture the struts. The collapsible frame described above can be erected from the condition illustrated in Figures 4 and 5 to the condition illustrated in Figures 8 and 9 in a generally continuous or discontinuous movement by exerting force on the nodes defined by the inner and outer pivots (13) and (14) connecting the corner defining crossed pairs of struts. In order to facilitate this, handgrips (23) may be associated with each of the inner pivots and optionally the outer pivots of the two composite frames at two ends of the frame. Erection is achieved simply by lifting the handgrip associated with the inner pivot and moving it towards the associated outer pivot. The result is that the entire frame is caused to move from its collapsed condition to its fully erected condition. At the same time, the crossed pairs of connector struts expand in the normal lazy tongs fashion and the upper set of these are shown in a fully extended position in Figure 9 in which they space the primary composite frames longitudinally. Additional handgrips (24) may be provided at the terminal ends of the outermost and lowermost struts, typically in the middle of the frame, so that they can be lifted and manipulated by moving opposite handgrips apart and then towards each other in order to collapse the frame from the erected condition.

If required, at least selected struts can be locked relative to another strut in order to lock the frame assembly in its erected condition. Typically, the free strut ends that lie in the same horizontal plane in the erected condition can be locked together such as by a releasable tie or the like. In this embodiment of the invention, a releasable tie (25) is provided. It is to be noted that a slight amount of stress may be imposed on the frame assembly to bring it to its most narrow A-frame configuration and, if this is done, appreciable rigidity is achieved of the frame.

In this particular embodiment of the invention feet (26) are provided on the ends of short extensions (27) to the lowermost terminal ends of the ground engaging struts in the erected condition, so that the A-frame can stand thereon.

In this particular embodiment of the invention the collapsible frame is particularly configured to support, in a generally flat condition, a flexible panel in the form of a banner (28). It is an important feature that the banner may be left in situ on the frame both in its collapsed and erected conditions. This being so, supports (29) illustrated in Figures 11 to 14 are provided at the outer ends of the struts. Each support is die cut from a flexible sheet of plastics material to the shape shown in Figure 11 in which it comprises a flexible web (30) having an anchorage formation

(31) at each end thereof. The anchorage formation includes lateral flanges (32) having perforations (33) that can be bent at right angles to the plane of the sheet and secured to the outer pivot (14) or, as the case may be the inner pivot. The anchorage formation can also be attached to the associated strut (12) by a pop rivet

(34). In the installed condition, the web defines said flexible arch that is bowed over the pivot and spaced therefrom so that the banner can be attached to it, for example by means of a loop or strap (35).

In order to ensure that the fabric of the banner does not become caught between struts when they scissors towards a closed condition, a deflector (36) (see in particular Figures 15 to 17) of elongate shape may be attached to each of the pairs of crossed struts on the outside of the median pivot. The deflector has anchorage formations (37) at each end thereof adapted for attachment to the inner side edge of each of the struts of a crossed pair thereof. Elongate slots (38) accommodate the strut so that the deflector is located on the opposite side of the strut from that to which the anchorage formation is attached. The strut thus passes through the slot with the deflector being directed towards the outer ends of the such that the central region (39) of the deflector is directed towards the outside of the frame in both the collapsed and erected terminal positions. The central region of the deflector can be provided with a permanent set urging it to project outwards rather than to fold inwards. The deflector can be configured such that its outermost central region in the erected condition is generally coplanar with that of the supports. The banner may thus also be attached to the deflector by means of loops or straps. As shown in Figures 16 and 17, the central region of the deflector thus moves outwards as the struts are moved to their positions in which the frame is in its collapsed condition and lifts the fabric panel away from the gap between the closing struts.

Turning now to the embodiment of the second variation of the invention, that is illustrated in Figures 20 and 21 , four crossed pairs of struts (40) having median pivots (41) configured so that the primary composite frame members indicated by numeral (42) assume a closed polygonal shape in the erected condition whilst assuming the usual nested configuration indicated in Figures 4 and 5 in the collapsed condition.

In this case there are four primary composite frame members (42) that are adapted to be operatively in spaced parallel horizontal planes and are interconnected by pairs of connecting struts (43) that, in this case, provide the height (longitudinal direction as discussed above) to the erected frame assembly. Figure 21 also illustrates the omission of one pair of transverse struts (indicated by numeral (44)) that may be required to form an access aperture.

The frame illustrated in Figure 21 is covered with a suitable flexible sheet material (45) and can thus be used to form a three-dimensional display structure to which advertising or other communications media may be applied in any required manner.

Alternatively, or in addition, the erected structure could serve as a container, in particular a large container, for holding loose articles, or for receiving refuse, as the case may be. The free edges (46) of the flexible sheet material can be releasably connected together along an operatively vertical edge, typically using a fastener system such as the hook and loop system widely known by the registered trademark ¹¹VELCRO" or a slide fastener.

As indicated in Figures 22 and 23, the primary composite frame members (47) and (48) could be configured to form, in the erected condition, an alternative polygonal shape such as a closed triangle (Figure 22) using only three crossed pairs of struts; or a closed pentagon (Figure 17) using five pairs of crossed struts. An hexagonal configuration is also envisaged.

It will be understood that numerous variations may be made to the various embodiments of the invention described above without departing from the scope hereof that is only limited to a collapsible framework of this general nature that can be used to form generally flat support structures for banners or walls with relatively sharp corners to the planes of the surfaces or walls.

Claims

CLAIMS:

1. A collapsible frame comprising at least two primary composite frames (10) of operatively generally polygonal shape in the erected condition and each of which is composed of a plurality of crossed pairs of struts (12, 19) wherein the struts of each pair are pivotally attached to each other by means of a median pivot (15, 20) in a central region of the length thereof with operatively inner and outer ends of the struts (other than those forming terminal ends of the composite frame member) being pivotally attached to a strut of a contiguous pivotally connected pair by means of inner and outer pivots (13, 14) to form a lazy tong construction and wherein the median pivots connecting the struts of at least two adjacent pairs thereof are inner median pivots (15) (as defined) such that the extended primary composite frame member adopts said operatively polygonal shape in an erected terminal condition, and wherein the inner and outer pivots of each primary composite frame are provided with formations (17) defining nodes to which inner and outer ends of a pair of crossed connecting struts (11) extending in the longitudinal direction are pivotally attached by means of pivots (18) having their axes at generally right angles to those of the said inner and outer pivots of the primary composite frame member and wherein the connecting struts of a pair thereof are pivotally attached (16) to each other in a central region of their length so that the connecting struts extend and retract in lazy tong fashion in unison with the struts of the primary composite frame members but in a plane at generally right angles thereto as the collapsible frame is moved from a collapsed terminal condition to an erected terminal condition and vice versa, the collapsible frame being characterised in that said two adjacent pairs of pivotally connected struts (12) constitute corner defining struts in the erected condition of the collapsible frame and the median pivots (15) are positioned, and the entire assembly is configured, such that in an erected terminal condition of the frame the struts of the corner defining struts that are connected by the inner pivot (13) extend at an angle to each other of at least 240 degrees with respect to an angle of from 5 to 15 degrees at which they extend to each other in the collapsed terminal condition of the collapsible frame.

2. A collapsible frame as claimed in claim 1 in which any additional crossed pairs of struts (19) connected directly to one of said two corner defining pairs of struts are interconnected by outer median pivots (20) (as herein defined) and any additional crossed pairs of struts connected to those are interconnected by inner median pivots (22), and so on, alternately.

3. A collapsible frame as claimed in either one of claims 1 or 2 in which the frame is of an A-frame type of structure.

4. A collapsible frame as claimed in any one of the preceding claims in which each of said nodes is in the form of a right angled bracket (17) having one flange attached to the inner or outer end of the associated strut by means of the inner or outer pivot, as the case may be, and the other flange of the bracket is pivotally attached to the associated end of the connecting strut.

5. A collapsible frame as claimed in any one of the preceding claims in which the free end (27) of an operatively ground engaging strut is extended beyond the pivot and provided with a ground engaging foot (26).

6. A collapsible frame as claimed in any one of the preceding claims in which the inner and outer pivots connecting the corner defining pairs of crossed struts are provided, in appropriate instances, with handgrips (23) whereby the frame can be manipulated to erect the collapsible frame.

7. A collapsible frame as claimed in any one of the preceding claims in which the free ends of operatively ground engaging struts are provided, in appropriate instances, with handgrips (24) for lifting and manipulating the frame from its erected condition to its collapsed condition.

8. A collapsible frame as claimed in any one of the preceding claims in which flexible cover panels (28) are releasably or permanently attached to the operatively outer ends of the struts, the operatively inner ends of the struts, or both, by way of separate dedicated supports (29).

9. A collapsible frame as claimed in any one of the preceding claims in which means (25) are provided for releasably fixing or arresting the positions of the pivotally inter-connected struts in their terminal operative positions.

10. A collapsible frame as claimed in any one of the preceding claims in which all corresponding inner and outer nodes of the primary composite frame members are inter-connected by means of pairs of connecting struts with appropriate pairs of connecting struts being omitted in order to provide any required access apertures or to reduce the cost when the relevant strength is not required.

11. A collapsible frame as claimed in any one of the preceding claims in which a deflector (36) of elongate shape and made of generally rigidly flexible material is attached to the side edge of each of two struts of a pivotally connected crossed pair thereof such that the central region of the deflector is directed towards the outside of the frame in both the collapsed and erected terminal positions of the frame.