According to another aspect of the present invention there is provided a foldable self-supporting structure comprising a series of at least three frame members, each frame member being hingedly connected to at least one other frame member, said frame members being arrangeable in either a folded state where the frame members lie next to one another such that there is substantially no void space between adjacent frame members, or in an erect state to form a self-supporting structure.

There is preferably an odd number of members, with all except the last member being frame members, the size of the members reducing progressively from first to last. The last member may also be a frame member.

The hinged connections between adjacent members preferably lie on parallel axes.

The members may be all cut from a single piece of stock material which may save wastage of material in production. The members may be rectangular, although it will be appreciated that other shapes can be used.

The hinged connections of a particular member are preferably spaced apart such that the connection with a larger member is at one end of the particular member and the connection with a smaller member is at an opposite end.

The members may be planar, and the members when folded are preferably coplanar.

Each member preferably has a flange to ensure that it may only be unfolded in one direction.

With five or more members, the foldable structure preferably takes the form of a truss having trihedral sections of reducing dimensions between the first section and the last section.

The structure may act as a first structure onto which further structures may be added.

When the members of the structure are arranged to form a self-supporting structure i.e. when they are unfolded, the structure may be three dimensional and there may be provided a releasable locking means to maintain the integrity of the structure.

According to a further aspect of the invention, there is provided a folding chair including a foldable self-supporting structure according to the invention having five hingedly connected members movable between an erect position in which the members form a bi-trihedral truss and a folded position in which the members are coplanar, seating means extending across one of the frame members.

The five members are preferably all frame members, and preferably rectangular, although the smallest member may not be.

The second frame member is preferably hingedly connected at or adjacent a first edge to the first frame member at or adjacent one edge thereof, the third frame member is preferably hingedly connected at or adjacent a first edge to the second frame member at or adjacent an edge opposite the first edge thereof, the fourth frame member is preferably hingedly connected at or adjacent a first edge to the third frame member at or adjacent an edge opposite the first edge thereof, and the fifth

member is preferably hingedly connected at one edge to the fourth frame member at an edge opposite the first edge thereof.

The chair preferably includes a releasable locking means for holding the members in the erect position.

The seating means may be an area of flexible material, such as fabric, or may comprise a base portion and a back portion hingedly connected together. The hinged connection may consist of flexible tapes or may include a suitable sliding means as described hereinafter.

The seating means may extend across the second frame member.

In the erect position, the arrangement is preferably such that the first frame member provides a rear, substantially upright portion, the second frame member slopes downwardly and forwardly from the top of the first frame member, the third frame member extends between the lower end of the second frame member and the lower end of the first frame member, the fourth frame member extends forwardly from the lower end of the third frame member, and the fifth member extends between the forward end of the fourth frame member and the lower end of the second frame member to provide support therefor.

According to a further aspect of the present invention there is provided a folding table including a foldable self-supporting structure according to the invention having five hingedly connected members movable between an erect position in which the members form a bi-trihedral truss and a folded position in which the members are coplanar, table surface means being provided by one of the members.

Four of the five members are preferably all frame members and preferably rectangular.

The first frame member is covered on one side to provide the table surface. The first frame member is preferably hingedly connected at or adjacent two edges to the second frame member at or adjacent a first edge thereof, the third frame member is preferably hingedly connected at or adjacent a first edge to the second frame member at or adjacent an edge opposite the first edge thereof, the fourth frame member is preferably hingedly connected at or adjacent a first edge to the second frame member at or adjacent the first edge thereof, and the fifth member is preferably hingedly connected at one edge to the fourth frame member at an edge opposite the first edge thereof. The table preferably includes a releasable locking means for holding the members in the erect position.

In the erect position, the arrangement is preferably such that the first frame member provides a top, substantially horizontal surface, the second frame member slopes downwardly and forwardly from the hinged connection with the first frame member, the third frame member provides a bottom, substantially horizontal base extending backwardly from the second frame member, the fourth frame member slopes downwardly and backwardly from the hinged connection with the second frame member to the third frame member, the fifth frame member extends upwardly from the fourth frame member to the first frame member to provide support therefor.

By way of example, three embodiments, a chair, a table, and a larger structure, of a self-supporting foldable structure according to the invention will now be ^• described with reference to the accompanying drawings, in which:

Figure 1 is a plan view of a chair in a erect position;

Figure 2 is a front view of the chair of Figure 1;

Figure 3 is a side view of the chair of Figures 1 and 2;

Figure 4 is an isometric view of the chair of Figures 1 to 3;

Figure 5 is a view illustrating the chair when folded;

Figure 6 is a side view of the seat of the chair showing the connection of the base to the back of the seat;

Figure 7 is a plan view of the underside of a table in the folded position;

Figure 8 is a plan view of a table in an erect position with some of the first frame member and the table surface cut away;

Figure 9 is a side view of the table of Figure 8;

Figure 10 is an end view of the table of Figures 8 and 9;

Figure 11 is an isometric view of the table of Figures 8 to 10; and

Figure 12 is a sketch view of an alternative structure in an open position.

Figures 1 to 6 show one specific embodiment of a foldable, self-supporting structure according to the invention. The structure in this embodiment takes the form of a chair with the structure itself having five members which, in an erect position, support a seating portion.

The configuration of the members is perhaps best seen initially in Figure 3 where a first frame member 10 forms a rear, substantially upright portion of the chair, a second frame member 11 is hingedly connected at 12 to the first frame member 10 and extends forwardly and downwardly therefrom. A third frame member 13 is hingedly connected at 14 to the second frame member 11 and extends downwardly and rearwardly therefrom to abut a lower portion of the first frame member 10 along a line 15.

Locking means such as a catch are provided to hold together the first and third frame members 10 and 13 at the line 15. A fourth frame member 16 is hingedly connected to the third frame member 13 at 17 and extends substantially forwardly therefrom with a leading edge 18 lying on the ground, floor or other surface on which the chair sits. A fifth member 19, in this case a frame member also _r is hingedly connected to the fourth frame member 16 at 20 and extends upwardly therefrom to support a lower portion of the second frame member 11 along line 21. Further locking means in the form of a catch or the like are provided to hold the fifth frame member 19 to the second frame member 11 or indeed the third frame 13 at the line 21.

Mounted on the second frame member 11 is a seating assembly having a base 25 hingedly connected to the second frame member 11 along the edge 26 and a back portion 27 hingedly connected to the second frame member 11 at edge 28. The base 25 and the back portion 27 are connected by flexible coupling links 29 which take the form of lengths of fabric or other flexible but substantially inextensible material. This arrangement allows the seat portion to be hinged upwardly above the plane of the second frame member 11 when it is wished to fold the chair.

Figures 1, 2 and 4 show other views of the chair, from which it will be seen that the frame members 10, 11, 13, 16 and 19 are all rectangular,, the dimensions being such that their external dimensions are progressively reduced so that the smallest frame member 19 can fit inside the fourth frame member 16 which in turn can fit inside the third frame member 13 which in turn can fit inside the second frame member 11 which in turn can fit inside the first frame member 10. The seating portion is well illustrated, particularly in Figure 4 which shows how the base 25 is connected to the back portion 27 by coupling links 29 of fabric or other flexible but substantially inextensible material.

Figure 5 shows the chair in a folded state viewed from the side away from that no which the seat portion lies, the position occupied by the base 25 and back portion 27 being shown in chain lines in Figure 5.

To transform the chair from the folded position of Figure 5 to the erect position of Figures 1 to 4, the following sequence is adopted:-

(1) the second frame member 11 is swung out from the first frame member 10 to approximately its final position

(2) the third frame member 13 is swung downwardly from the second frame member 11 and.held on to the first frame member 10

(3) the fourth frame member 13 is lowered from the third frame member 11 until it touches the ground or floor

(4) the fifth frame member 19 is raised and held against the second frame member 11 or the third frame member 13

(5) the base 25 of the seat is pushed downwardly into the position shown in Figure 4 if it has not fallen there due to gravity.

This sequence is reversed to fold the chair, although it will be appreciated that other sequences might be used.

It will be appreciated that variations as to the precise manner of construction of the chair may be made. For example, variations can be made to the precise positions at which the frame members are locked together. Also instead of using coupling links 29 a single coupling link of flexible but substantially inextensible material may be used.

Another manner in which the base 25 may be connected to the back 27 is provided by a hinged means in combination with a sliding link attached to the back 27, as illustrated in Figure 6. — _

Figures 7 to 11 show another specific embodiment of a foldable, self-supporting structure according to the invention. The structure in this embodiment takes the form of a table with the structure itself having five members which, in an erect position, provide a table surface.

The configuration of the members is perhaps best seen initially in Figure 9 where a first frame member 52 forms the top, substantially horizontal portion of the table, a second frame member 53 is hingedly connected at 54 to the first frame member 52 and extends forwardly and downwardly therefrom. A third frame member 55 is hingedly connectd at 56 to the second frame member 53 and forms a bottom, substantially horizontal portion of the table extending backwardly therefrom. A fourth frame member 57 is hingedly connected at 58 to the second frame member 53 and extends backwardly and downwardly therefrom to abut a back portion of the third frame member 55 along a line

59. Locking means such as a catch are provided to hold together the third and fourth frame members 55 and 57 respectively at the line 59. The fifth member 60, in this case a framed member also, is hingedly connected to the fourth frame member 57 at 61 and extends upwardly therefrom to support the first frame member 52 along the line 62. Further locking means in the form of a catch or the like are provided to hold the fifth frame member 60 to the first frame member 52 at the line 62.

Figures 7, 8, 10 and 11 show other views of the table, from which it will be seen that the frame members

60, 57, 55, 53 and 52 are all rectangular and can fit inside the first frame member 52, to which the table top is attached.

Figure 7 shows the underside of the table in the folded state.

To transform the table from the folded position of Figure 7 to the erect position of Figures 8 to 11, the following sequence is adopted:-

(1) the third frame member 55 is swung out from the first frame member 52;

(2) the fourth frame member 57 is swung out from the second frame member 53 and held onto the third frame member 55 at the line 59;

(3) the first frame member 52 is swung away from the second frame member 53 and the fifth frame member 60 is swung out from the fourth frame member 57 and held onto the first frame member at the line 62.

This sequence is reversed to fold the table, although it will be appreciated that other sequences might be used.

It will be appreciated that variations as to the precise manner of construction of the table may be made. For example, variations can be made to the precise positions at which the frame members are locked together.

Merely as an illustration. Figure 12 shows a larger structure which includes a plurality of members hingedly connected together but capable of fitting inside one another. All except for the smallest member are frame members and the smallest member may also be a frame member. The connection sequence is as follows:-

Largest member 40 is connected to second largest member 41 which is connected to third largest member 42 which is connected to fourth largest member 43 which is connected to fifth largest member 44, which is connected to sixth largest member 45 which is connected to seventh largest member 46 which is connected to eighth largest member 47 which is connected to ninth largest member 48 which is connected to tenth largest member 49 which is connected to eleventh largest member 50 which is connected to smallest member 51. The structure produced has a multitude of uses, for example, a temporary mast, scaffolding, a bridge support, a car ramp, ladder or steps, or a tower crane. The structure may be fitted to a

lorry or trailer. If this is done, when the structure is folded its planar surface may be used as a deck. Many other possibilities exist and the advantage associated with the structure is that it is capable of holding within itself to occupy no more space than the largest frame member.

A structure according to the invention also has many applications for other pieces of furniture, as well as the chair and table described with reference to Figures 1 to 11. With different configurations, a structure according to the invention could be used as the supporting portion of a stool or a light holder or as a folding bed or a folding clothes horse, or indeed a shelving system or a variety of different chairs, tables or settees. All these structures could have the aforementioned advantage of being able to fold within the dimensions of the largest frame member.

A structure according to this invention can of course be made from many materials, such as plastics, wood, metal, tubular steel etc., depending on the circumstances in which it is to be employed.

The members of the structure may be either tight fitting or loose fitting. A locking means could be a pin on one member and a sunken tube with a spring-loaded catch on another, so that the two members may be held firmly together.

Means may be provided for maintaining the structure in the folded position.

It will be appreciated that the foregoing description is by way of example only and that variations and modifications may be made within the scope of the invention.