Abstract:
A self-expanding display unit ( 1 ) comprising at least one display sheet ( 3, 5 ) of a substantially rigid and foldable material having a display face ( 7,9 ), a biasing means for bending the display face of the display sheet into a substantially convex shape, and bracing means ( 2 ) acting against the biasing means to limit the amount by which the display sheet ( 3, 5 ) bends. The display sheet comprises a plurality of panels, delimited from adjacent panels by crease lines. The bracing means ( 2 ) comprises a single, substantially rigid and foldable bracing sheet ( 2 ) having a plurality of bracing panels ( 50 ), each of which is delimited from an adjacent bracing panel by a fold line ( 52 ). The fold lines ( 52 ) and the crease lines are coincident with each other. Such a device is stable in operation and is efficient to use and manufacture.

Description:
RELATED APPLICATIONS 
     The subject application is a U.S. National Stage application that claims the priority of International Application No. PCT/EP2007/055271, filed on 30 May 2007, which claims the priority of Irish National Application Nos.: S2007/0279, filed on 17 Apr. 2007, S2007/0244, filed on 5 Apr. 2007, and S2006/0411, filed on 30 May 2006. 
     The present invention relates to a self-expanding display unit comprising at least one display sheet of a substantially rigid and foldable material, the display sheet having a display face, a biasing means for bending the display face of the display sheet into a substantially convex shape, the biasing means comprising one or more resiliently extensible members, and bracing means acting against the biasing means to limit the amount by which the display sheet bends. The display sheet comprises a plurality of panels, delimited from adjacent panels by crease lines. Such devices are commonly used as information displays in many areas of business, such as retail and marketing. 
     Self-expanding display units are directed towards satisfying a demand for temporary information displays. Such temporary information displays are typically used in retail locations as part of temporary promotional displays, such as those used to promote a new product or special offer. Similarly, temporary information displays are used at sales fairs, conferences and other situations where temporary, promotional signage is required. For these situations, marketing and sales personnel require temporary information displays that can be easily transported, easily set-up and that are relatively inexpensive. In order to satisfy these requirements, a number of display units constructed from cardboard, have been developed. Cardboard is lightweight, portable, inexpensive and, while quite rigid, can also be easily folded. This ability to be folded is very useful as it allows the display units to be folded substantially flat to a more compact shape and reduced size when not in use. 
     Typically, the temporary display units have a number of elastic bands that are arranged to cause the temporary display unit to maintain a particular shape when set up. Furthermore, the elastic bands are usually arranged to help the display unit self-expand from a folded, stored configuration to an expanded, operating configuration. The use of elastic bands allows the display units to be stored in a relatively flat state, thus stretching the elastic bands so that when the display unit is released from its folded position, the elastic bands relax and pull the cardboard display unit into the desired shape. When in use, the display unit can be a self-supporting three dimensional shape that does not require much adjustment once it has been set-up. 
     One such construction of foldable display unit is that disclosed in EP1395971 (l&#39;Hotel, François). This construction of foldable display unit comprises a display sheet connected to a plurality of smaller sheets or strips by way of a number of elastic bands. The display sheet bends under the action of the elastic bands until its edges abut against the edges of the strips. Thus the combination of the strips and elastic bands hold the display sheet in the bent position when the unit is in use. In this way the unit can take on a three dimensional shape when in use, and is somewhat self-supporting, generally with the use of one or more additional ground-engaging feet. The supporting strips are rigid and are not designed to be folded and therefore must be carefully positioned relative to the display sheet so as not to interfere with the folding of the unit. The display sheet comprises a number of crease lines, about which the unit folds when it is not in use. These crease lines define panels intermediate the crease lines. The supporting strips are placed so that they are positioned directly behind the panels. This ensures that the supporting strips are positioned away from the folding areas of the display unit, as defined by the crease lines. In this way, the supporting strips will not hinder the folding of the unit in any way. 
     While much effort has gone into the development of display units that are easily transported, easily set-up and relatively inexpensive to produce, there are some problems associated with the temporary display units in general. First of all, the manufacturing process can be relatively complex. The requirements that the display unit has means to keep the display sheet bent and that those means do not interfere with the folding of the display unit has heretofore meant that many individual elements were required to construct the display unit. The manufacture of the display unit therefore entails manufacture of a large number of pieces and their subsequent assembly. This can be a time-consuming and intricate operation to perform. 
     A further problem with the known display units is that many of the known types of display units are relatively unstable. The combination of one or two display sheets and a number of strips does not always provide a sufficiently stable body and it is necessary to provide additional ground-engaging supports or feet to ensure the unit remains upright when in use. Such ground-engaging supports further complicate the manufacturing process and can also cause difficulties when a user comes to erect the display unit. 
     It is an object therefore of the present invention to provide a self-expanding display unit that is simple to manufacture and construct. It is a further object of the invention to provide a self-expanding display unit that is stable in use. 
     STATEMENTS OF INVENTION 
     According to the invention there is provided a self-expanding display unit comprising at least one display sheet of a substantially rigid and foldable material, the display sheet having a display face; a biasing means for bending the display face of the display sheet into a substantially convex shape, the biasing means comprising one or more resiliently extensible members; and bracing means acting against the biasing means to limit the amount by which the display sheet bends, the display sheet comprising a plurality of panels, delimited from adjacent panels by crease lines characterised in that the bracing means comprises a single, substantially rigid and foldable bracing sheet having a plurality of bracing panels, each of which is delimited from an adjacent bracing panel by a fold line, the bracing sheet being positioned relative to the display sheet such that each fold line of the bracing sheet is coincident with a crease line of the display sheet; the display sheet and the bracing sheet being foldable together at their crease lines and fold lines respectively. 
     In this way, the display unit will comprise a small number of components, thereby greatly reducing the machining required in the manufacture of the display unit. Furthermore, reducing the number of components also reduces the time and complexity involved in assembling the components into the final structure. As the bracing means comprise a single component, it is a relatively simple matter to connect the bracing means and the display sheet together by way of the biasing means. Additionally, the use of a single bracing sheet will assist in the self-expanding action of the display unit. This is due in part to the extra layer of material present at each fold when which will result in an increased bias towards an unfolded state at each fold. Furthermore, it is believed that the biasing means acting on the bracing sheet will cause a force to act against not only the bracing panel to which it is connected but also to the adjacent bracing panels, thereby increasing the self-expanding action. This results in a display unit that is easier to expand from a folded configuration. 
     In one embodiment of the invention there is provided a self-expanding display unit in which the bracing sheet has an upper end, a lower end and two side edges, the lower end of the bracing sheet being coincident with a lower end of the display sheet such that the lower end of the bracing sheet and the lower end of the display sheet each form a ground-engaging support for the display unit. The provision of at least two ground-engaging members, in the form of the lower end of the display sheet and the lower end of the bracing sheet, provides improved stability to the display unit when it is in use. 
     In another embodiment of the invention there is provided a self-expanding display unit in which each bracing panel of the bracing sheet comprises at least one aperture for connecting the biasing means to the bracing sheet. This is a simple and efficient manner of providing for the connection of the biasing means to the bracing panel. 
     In one embodiment of the invention there is provided a self-expanding display unit in which each bracing panel of the bracing sheet comprises a plurality of apertures located at the side edges of the bracing sheet for connecting the biasing means to the bracing sheet. In this way, the apertures do not extend greatly into the sides of the bracing panels thereby allowing areas at the centre of the panels to be cut out without impeding the operation of the display unit. The cut out areas may then be used to accommodate the fitting of inserts such as shelving units or the like. 
     In another embodiment of the invention there is provided a self-expanding display unit in which the apertures comprise a narrow cut extending inwardly from the edge of the sheet and terminating in a circular aperture. In this way, the biasing means may be slid through the narrow cut to sit in the circular aperture. The circular aperture is particularly advantageous as the biasing means may exert a pull on the aperture and it is less likely to tear under normal operating conditions. 
     In a further embodiment of the invention there is provided a self-expanding display unit in which each bracing panel of the bracing sheet comprises a pair of crescent-shaped apertures for connecting the biasing means to the bracing sheet. This is a particularly effective way of providing for the connection of the bracing sheet to the biasing means. Additionally, the crescent-shaped cut-outs reduce the chance of the biasing means tearing the bracing sheet during the day to day operation of the display unit. 
     In a further embodiment of the invention there is provided a self-expanding display unit in which the bracing sheet comprises a further panel, forming a ground-engaging panel, which extends from the lower end of the bracing sheet and is delimited from the bracing panel adjacent the lower end of the bracing panel by a fold line. In this way, the ground-engaging panel will extend below the display sheet and in use, will rest flat on the ground, substantially orthogonal to the bracing sheet. The lower end of the display sheet will therefore rest on the ground-engaging panel while the display unit is in use. The ground-engaging panel will provide an increased footprint for the display unit, thereby providing increased stability. 
     In an alternative embodiment of the invention there is provided a self-expanding display unit in which the ground engaging panel is substantially semi-elliptical in shape. In this way, the shape of the ground-engaging panel will mirror the shape of the display faces when the display unit is in use. 
     In one embodiment of the invention there is provided a self-expanding display unit in which the ground-engaging panel is substantially the same width as the display face. In this way, the display unit comprising the ground-engaging panel will still fold in a compact manner and the size of the folded display unit will not increase. 
     In another embodiment of the invention there is provided a self-expanding display unit in which the bracing sheet comprises a pair of ground-engaging panels, both extending from the lower end of the bracing sheet. In this way, a further increased footprint may be provided to the display unit, thereby increasing stability. Additionally, the ground-engaging panels preferably extend below the display unit in opposite directions, again increasing the footprint of the unit and increasing stability. 
     In a further embodiment of the invention there is provided a self-expanding display unit in which the area of the bracing panel adjacent the upper end of the bracing sheet is less than that of the other bracing panels of the bracing sheet. This reduces the amount of material required to form the bracing sheet, reducing the cost of materials used in the manufacture of the display unit. Furthermore, as the uppermost panel of the bracing sheet is not as large as the other panels, it will not reach the top of the display sheet and will be less likely to be seen when looking at the upper panel of the display sheet. This configuration of bracing sheet is therefore more aesthetically pleasing than a bracing sheet having a full size upper panel. Additionally, it may be possible to use the spare material omitted from the uppermost panel of the bracing sheet elsewhere in the manufacture of the display unit. Finally, by reducing the weight of the bracing panel adjacent the top of the display unit, the display unit will have a greater proportion of its weight located lower down thereby providing a more stable display unit. 
     In one embodiment of the invention there is provided a self-expanding display unit in which each panel of the display sheet is delimited from an adjacent panel by a pair of spaced-apart substantially parallel crease lines. In a further embodiment each bracing panel of the foldable bracing sheet is delimited from an adjacent bracing panel by a pair of spaced-apart substantially parallel fold lines. In this way, simple and convenient folding of the display unit may be facilitated. Due to the inherent thickness and rigidity of the material, a fold where the material will completely double back on itself i.e. a 180° fold is better accommodated by two crease lines, essentially allowing two folds, each of approximately 90°. Additionally, as there are at least two layers of the substantially rigid and foldable material used to form the bracing and display sheets present at each fold, the fold will have a certain width associated with it and a certain amount of space is required to accommodate this material at the fold. This space is advantageously provided by using two, slightly spaced-apart crease lines at each fold. This presence of the pair of slightly spaced apart crease lines gives a squared edge to the fold when the display unit is in the folded, storage configuration, which allows the display unit to fold in a more compact manner. 
     In a further embodiment of the invention there is provided a self-expanding display unit in which the bracing sheet has a tab along one side edge thereof for engagement with a complimentary slot formed in the display sheet to limit relative movement therebetween. Ideally, there are provided a pair of tabs and a pair of complimentary slots, the tabs being located adjacent the lower end of the bracing sheet. The use of a tab and complimentary slot allows the position of the bracing sheet relative to the display sheet to be substantially fixed. The presence of the tab in the slot prevents longitudinal movement of the bracing sheet relative to the display sheet. This ensures that the crease lines of the bracing sheet will always be coincident with the fold lines of the display sheet, allowing the easy folding of the display unit when required. Furthermore, placing the tabs adjacent the lower end of the bracing sheet allows them to be less visible than if they were higher up the bracing sheet. 
     In an alternative embodiment of the invention there is provided a self-expanding display unit in which the display face has at least two edges, substantially vertical in use, and the slots are formed therein. In this way, the tabs and slots do not interfere with the main area of the display face, thereby allowing information to be printed easily on the display face and maximising the effectiveness of this information. 
     In one embodiment of the invention there is provided a self-expanding display unit in which there are two pairs of slots, one pair adjacent an upper end of the display sheet and the other pair adjacent the lower end of the display sheet. This facilitates ease of assembly of the display unit as the display sheet does not have a top or bottom section until the bracing sheet has been fitted. The display sheet is symmetrical and can have the bracing sheet fitted with the tabs at either end. Furthermore, when in use, the spare pair of slots may be used to support additional elements such as a holder for leaflets or other such material. In some cases, one pair or slots may be particularly adapted to facilitate fitting additional parts to the display unit. 
     In another embodiment of the invention there is provided a self-expanding display unit in which there are provided a pair of display sheets each having a display face and a plurality of panels delimited from an adjacent panel by crease lines, the display sheets being connected together adjacent the side edges thereof with their display faces back-to-back, the display sheets thereby, in use, forming a structure substantially elliptical in horizontal cross-section, the crease lines of the first display sheet being coincident with the crease lines of the second display sheet. In this way, a versatile display unit is provided, having two displays faces, both of which may have promotional content or the like printed thereon. Additionally, the provision of an additional display sheet provides an additional ground engaging member, thereby increasing the stability of the display unit. 
     Furthermore, a display unit of this construction will be substantially symmetrical about a vertical axis, thereby increasing its usefulness and stability. 
    
    
     
       DETAILED DESCRIPTION OF THE INVENTION 
       The invention will now be more clearly understood from the following description of some embodiments thereof, given by way of example only, with reference to the accompanying drawings in which: 
         FIG. 1  is a front view of a self-expanding display unit according to the invention in an operating configuration; 
         FIG. 2  is top plan view of the display unit shown in  FIG. 1 ; 
         FIG. 3  is a side view of the display unit; 
         FIG. 4  is a side view of the display unit in a storage configuration; 
         FIG. 5  is a front view of the bracing sheet; 
         FIG. 6  is a front view of a display sheet; 
         FIG. 7  is a front view of an alternative embodiment of bracing sheet; 
         FIG. 8  is a front view of an alternative embodiment of a self-expanding display unit according to the invention in an operating configuration; 
         FIG. 9  is top plan view of the display unit shown in  FIG. 8 ; 
         FIG. 10  is a side view of the display unit in  FIG. 8 ; 
         FIG. 11  is a side view of the display unit in  FIG. 8  in a storage configuration; 
         FIG. 12  is a front view of the bracing sheet used in the display unit of  FIG. 8 ; 
         FIG. 13  is a front view of a display sheet used in the display unit of  FIG. 8 ; 
         FIG. 14  is a front view of an alternative embodiment of bracing sheet to be used in the display unit of  FIG. 8 ; 
         FIG. 15  is a front view of an alternative embodiment of a self-expanding display unit according to the invention in an operating configuration; 
         FIG. 16  is top plan view of the display unit shown in  FIG. 15 ; 
         FIG. 17  is a side view of the display unit in  FIG. 15 ; 
         FIG. 18  is a diagrammatic side view representation of the display unit in  FIG. 15  in a storage configuration; 
         FIG. 19  is a detail of the circled section in  FIG. 18 ; 
         FIG. 20  is an exploded view of a bracing sheet used in the display unit of  FIG. 15 ; 
         FIG. 21  is an exploded view of an alternative embodiment of bracing sheet to be used in the display unit of  FIG. 15 ; 
         FIG. 22  is a front view of an alternative embodiment of bracing sheet; and 
         FIG. 23  is a front view of an alternative embodiment of self-expanding display unit. 
     
    
    
     Referring to the drawings, and initially to  FIGS. 1 to 3  thereof, there is shown a display unit, indicated generally by the reference numeral  1 , comprising an elongate bracing sheet (not shown) and a pair of elongate display sheets  3 ,  5 , each having a display face  7 ,  9 . Each display sheet  3 ,  5  is divided into four panels  11   a ,  11   b ,  11   c ,  11   d  by pairs of crease lines  13   a ,  13   b  (shown as dashed lines). The crease lines  13   a ,  13   b  are formed during the manufacture of the display unit  1 , and allow the substantially rigid material used to construct the display unit to fold easily at those lines. At each longitudinal edge of each display face, there is provided a pair of slots  15 , one slot in the uppermost panel  11   a  and one in the lowermost panel  11   d . Each of the slots  15  in the lowermost panel  11   d  engage with one of a pair of complimentary tabs  17  on the bracing sheet. Therefore, the bracing sheet  2  may be connected to the display sheet  3  so that tabs  17  engage slots  15  on the uppermost panel  11   a  or on the lowermost panel  11   d.    
     Referring now to  FIG. 4 , there is shown a diagrammatic representation of the display unit  1  when folded. It can be seen that when folded the display unit  1  takes on a substantially serpentine shape, with the pairs of crease lines  13   a ,  13   b  defining the area where the display unit  1  folds. The display unit will fold through substantially 180° at each pair of crease lines  13   a ,  13   b  such that the panels  11   a ,  11   b ,  11   c ,  11   d  will lie substantially parallel to each other, one on top of the other. The 180° fold comprises a combination of two 90° folds, one fold at each crease line  13   a ,  13   b.    
     Referring now to  FIG. 5 , there is shown the elongate bracing sheet  2 , having four bracing panels  50   a ,  50   b ,  50   c ,  50   d  delimited by pairs of fold lines  52   a ,  52   b . The bracing sheet is not shown to scale. The fold lines are formed during the manufacture of the display unit  1 , and allow the substantially rigid material used to construct the display unit to fold easily at those lines. The top panel  50   a  is smaller in area than the remaining panels and has an arcuate cut  54  in its top edge. Each of the lower bracing panels  50   b ,  50   c ,  50   d  has a plurality of apertures  56  in their edges for connection to the display sheets by elastic bands (not shown). The top panel  50   a  has two standard apertures  56  in the side edge and two smaller apertures  58  in the top edge. The bracing sheet  2   56 ,  58  therefore comprises sixteen apertures, seven in each side and two in the top. Each rectangular bracing panel  50   b ,  50   c ,  50   d  comprises four standard apertures  56 , two in each side. The standard apertures  56  take the form of a thin cut in the material of the bracing sheet, the thin cut having a straight portion extending inwardly from the edge and substantially orthogonal thereto, and a curved portion extending from the straight portion in a substantially hook shape. The standard aperture  56  then terminates in a substantially circular portion  57 , in which the elastic band (not shown) will sit when fitted. 
     For each of the rectangular bracing sheets  50   b ,  50   c ,  50   d , on each side the curved portions of the two standard apertures  56  curve towards each other in that the upper aperture in a standard bracing panel curves downward and the lower aperture curves upwards. The smaller apertures  58  take the form of a thin cut having a straight portion extending inwardly from the edge and substantially orthogonal thereto which terminates in a substantially circular portion  59  in which the elastic band will sit. The bottom panel  50   d  of the bracing sheet  2  has a pair of tabs  17  for engagement with the slots  15  on the display sheets  3 ,  5 . It will be understood that the straight and curved portions of these apertures  56 ,  58  may comprise a simple cut in the material of the bracing panel and will therefore have no substantial width. Alternatively, these portions may comprise cut-out portions having a narrow width of the order of 2 to 5 mm, preferably between 3 mm and 5 mm. The substantially circular portions  57 ,  59  will comprise a cut-out shape. 
     Referring now to  FIG. 6 , there is shown a drawing of one elongate display sheet, indicated generally by the reference numeral  3 , wherein like parts have been given the same numerals as before. Each display sheet  3  comprises four panels  11   a ,  11   b ,  11   c ,  11   d  and has an elongate display face  7  and a pair of flaps  29  at the side edges of the display sheet  3 . The flaps  29  have a plurality of notches  31  therein for engagement with elastic bands (not shown) thereby allowing the display sheet  3  to be connected to the bracing sheet  2  and another display sheet. The notches  31  comprise a thin cut curving from the outside edge of the flap and terminating in a circular portion, in which the elastic band (not shown) will sit when fitted. Each panel  11   a ,  11   b ,  11   c ,  11   d  of the display sheet  3  comprises four notches, two on each side. The curve of each notch forms a semi-circle, with the upper notch in a panel initially curving upwards from the outside edge of the flap  29  before curving downwards and terminating in the circular portion, while the lower notch curves downwards initially from the outside edge of the flap and then curves upwards before terminating in the circular portion. The flaps  29  also have Vee-shaped notches  33  at the crease lines  13   a ,  13   b  to facilitate folding at these areas. The display face of the display sheet is wider than the bracing sheet. 
     Referring now to  FIG. 7 , there is shown an alternative embodiment of an elongate bracing sheet indicated generally by the reference numeral  60 , having four bracing panels  62   a ,  62   b ,  62   c ,  62   d  delimited by pairs of fold lines  64 ,  64   b . The fold lines are formed during the manufacture of the display unit  1 , and allow the substantially rigid material used to construct the display unit to fold easily at those lines. Each of the bracing panels  62   a ,  62   b ,  62   c ,  62   d  has a pair of crescent-shaped cut-outs  66  for engagement with elastic bands (not shown) thereby allowing the bracing sheet  60  to be connected to the display sheets  3 ,  5 . The points of the crescent-shaped cut-outs  66  face the edges of the bracing sheet  60  and effectively form notches for the reception of the elastic bands. The bottom panel  62   d  of the bracing sheet  60  has a pair of semi-circular tabs  17  for engagement with the corresponding slots  15  on the display sheets  3 ,  5 . 
     To assemble the self-expanding display unit  1  of the invention, the flaps  29  of each display sheet  3 ,  5  are folded back on themselves along the lines marked X-X and the two display sheets  3 ,  5  and the bracing sheet  2 ,  60  are connected together using elastic bands (not shown) so that the flaps  29  of one display sheet  3  abut the flaps on the other display sheet  5 , with the display faces  7 ,  9  facing outwards. The elastic bands will be connected between the notches  31  of the display sheets  3 , 5  and the apertures  56 ,  58 , or crescent shaped cut-outs  66  of the bracing sheet  2 ,  60 . In general, two elastic bands (not shown), one at each side, will be used to connect a bracing panel  50 ,  62  of the bracing sheet  2 ,  60  to the corresponding panels  11  of the two display sheets  3 ,  5 . The elastic bands (not shown) are chosen such that they will be slightly stretched when the display sheets and bracing sheets are lying flat against each other in a stored configuration. Therefore, a single elastic band will be looped through the pair of notches  31  nearest a bracing panel and the elastic band will then be looped through the two apertures  56  (or  56  and  58  for the top panel) or the crescent  66  of the bracing panel adjacent the notches  31 . Another elastic band will be provided along the other edge of the bracing panel to engage the notches and apertures nearest the other edge of the bracing panel. Each bracing panel will have a pair of elastic bands, one along either edge of the bracing sheet. 
     In use, when no external force is exerted on the display unit  1 , the elastic bands, which are slightly stretched, will attempt to contract to their resting shape. In doing so they will pull the edges of the display sheets inwards until they abut the edges of the bracing sheet. At this point the elastic bands can contract no further, as the movement of the display sheets is limited by the bracing sheet. As the edges of display sheets  3 ,  5  are pulled inwards, the display faces  7 ,  9  of display sheets  3 ,  5  are forced into a convex shape thereby forming a structure having a substantially elliptical horizontal cross-section. In order to store the display unit, the unit may be collapsed inwardly by pressing on the display faces  7 ,  9  so that the elastic bands (not shown) are stretched once more and the display sheets  3 ,  5  are flattened against the bracing sheet  2 . The display unit  1  may now be folded about the crease lines  13   a ,  13   b  into the substantially serpentine shape shown in  FIG. 4 . Depending on the force of the elastic bands and the weight of the material used to construct the bracing and display sheet, the display unit may require some form of constraint to keep it folded, however, the weight of the materials in the display unit may be sufficient to keep the device folded. To expand the device, it suffices to hold onto the side edges of one of the upper panels of the display unit and lift it off the ground. The elastic bands will contract once more, bending the display sheets to create a self-supporting display unit. 
     Referring now to  FIGS. 8 to 14 , there is shown an alternative embodiment of the display unit in which like parts have been the same reference numerals as before. Referring initially to  FIGS. 8 to 10  there is shown a display unit indicated generally by the reference numeral  100  comprising an elongate bracing sheet  120 , a pair of elongate display sheets  3 ,  5  each having a display face  7 ,  9  respectively. The display unit  100  further comprises a ground-engaging foot  110 . The ground engaging foot  110  is shown being substantially a trapezium shape having a section removed from its base. The ground engaging foot is fitted through slots  112  in each display sheet  3 ,  5  and bracing sheet  120 ,  160  such that its base will rest on the ground when the display unit  100  is in use. The slot  112  is substantially triangular in shape, tapering towards its upper end and has a horizontal slit at its apex and the slots in each display sheet and bracing sheet will be aligned such that the ground engaging foot  110  will be oriented substantially orthogonally to the bracing sheet  120 ,  160  in use. The ground-engaging foot  110  lies flat against the display faces  130 ,  150  of the display unit  100  when the display unit  100  is in its folded storage configuration. It is envisaged that a number of slots  112  and ground engaging feet  110  may be provided if desired. Preferably, these would be spaced evenly across the width of the display sheet and bracing sheet. For example, two or three feet may be provided if desired. 
     Referring now to  FIGS. 15 to 19 , there is shown an alternative embodiment of the display unit in which like parts have been given the same reference numerals as before. Referring initially to  FIGS. 15 to 17  there is shown a display unit indicated generally by the reference numeral  200  having a ground-engaging support  210  which protrudes slightly below the lowermost panels  11   d  of the elongate display sheets  3 ,  5 . The ground engaging support  210  could however lie flush with the lowermost panels  11   d  of the elongate display sheets when in an operating position splayed outwardly. The ground-engaging support  210  is formed from two flat ground-engaging panels  210   a ,  210   b  each being substantially semi-circular in shape and having one straight edge and one arcuate edge. The ground-engaging panels  210   a ,  210   b  will rest on the ground, substantially orthogonal to the display unit  200 .  FIG. 16  shows the increased footprint of the display unit having the ground-engaging panels, giving rise to increased stability. The footprint will be substantially elliptical in shape, with the major axis of the ellipse defined by the straight edge of the ground-engaging panels and the minor axis of the ellipse defined by the depth of the ground-engaging support formed by the two ground-engaging panels. 
     Referring now to  FIG. 18 , there is shown a side view of the display unit  200  in a folded configuration. It can be seen that when folded the display unit  200  takes on a substantially serpentine shape, with the pairs of crease lines  13   a ,  13   b  defining the area where the display unit will fold. The display unit will fold through substantially 180° at each pair of crease lines  13   a ,  13   b  such that the panels  11   a ,  11   b ,  11   c ,  11   d  will lie substantially parallel to each other. Each ground-engaging panel  210   a ,  210   b  protrudes beyond the end of the lowermost panels of the display sheets  3 ,  5  and is folded 180° so that one ground-engaging panel  210   a  will lie along one display sheet  5  while the other ground-engaging panel  210   b  will lie along the other display sheet  3 . A more detailed view of the circled area in  FIG. 18  is shown in  FIG. 19 . For the sake of clarity  FIG. 19  shows the side edges of the display sheets  3  and  5  slightly spaced apart however in reality they will abut each other. The two ground-engaging panels  210   a ,  210   b  protrude from the ends of the display sheets and are folded back so as to lie along the display faces  7 ,  9  of the display sheets  3 ,  5 . The side edges of the display sheets  3 ,  5  shown in  FIG. 19  correspond to the edges formed when the flaps  29  of the display sheet are folded over. As the ground-engaging panels  210   a ,  210   b  are attached to the bracing sheet  202  forming a unitary body and as the bracing sheet  202  will in general lie on one side of the two flaps, the ground-engaging panels are therefore shown protruding from the edge of one display sheet. 
     Referring now to  FIG. 20  in which like parts have been given the same reference numerals as previously, there is shown the elongate bracing sheet  220 , having four rectangular bracing panels  50   a ,  50   b ,  50   c ,  50   d  delimited by pairs of fold lines  52   a ,  52   b . and a ground-engaging panel  210   a , the bracing panels being delimited from each other by pairs of fold lines  52   a ,  52   b  and the ground-engaging panel  210   a  being delimited from the lowermost bracing panel  50   d  by a single fold line  252 . The fold lines are formed during the manufacture of the display unit  1 , and allow the substantially rigid material used to construct the display unit to fold easily at those lines. Each of the bracing panels  50   a ,  50   b ,  50   c ,  50   d  has a plurality of apertures  56  in their edges for connection to the display sheets by elastic bands (not shown). The bracing sheet  220  therefore comprises sixteen apertures. Each rectangular bracing panel  50   a ,  50   b ,  50   c ,  50   d  comprises four standard apertures  56 , two in each side. The standard apertures  56  take the form of a thin cut in the material of the bracing sheet, the thin cut having a straight portion extending inwardly from the edge and substantially orthogonal thereto, and a curved portion extending from the straight portion. The standard aperture  56  then terminates in a substantially circular portion, in which the elastic band (not shown) will sit when fitted. For each of the rectangular bracing sheets  50   a ,  50   b ,  50   c ,  50   d , on each side the curved portions of the two standard apertures  56  curve towards each other in that the upper aperture in a standard bracing panel curves downward and the lower aperture curves upwards. The lowermost bracing panel  50   d  of the bracing sheet  2  may comprise a pair of tabs (not shown), similar to the embodiments described above, for engagement with the slots  15  on the display sheets  3 ,  5 . The lowermost bracing panel  50   d  of the bracing sheet  220  further mounts the ground-engaging panel  210   a  which corresponds in shape to a segment of a circle, wherein its chord defines the base of the lowermost bracing panel  50   d  and extends beyond the width of the bracing sheet  220 . 
     Also shown in  FIG. 20  is a complementary panel  212  comprising the ground-engaging panel  210   b , which corresponds in shape and size to the ground-engaging panel  210   a  of the bracing sheet  220 . The complementary panel  212  further comprises a rectangular additional bracing panel  219 , delimited from the ground-engaging panel  210   b  by a fold line  254 , wherein the chord of the ground-engaging panel  110   b  defines the base of the additional bracing panel  119  and the fold line  120 . Furthermore the additional bracing panel  219  is the same width as the bracing panels  50   a ,  50   b ,  50   c ,  50   d  and comprises four standard apertures  256  positioned such that when the two ground-engaging panels  210   a ,  210   b  are arranged in line with each other, the standard apertures  256  of the additional bracing panel  219  will be co-located with the standard apertures  56  of the lowermost bracing panel  50   d  of the bracing sheet  220 . Indeed, the additional bracing panel may be permanently affixed by glue or other means to the bracing sheet panel  50   d.    
     To assemble the bracing sheet  220 , the complementary panel  212  is secured to the bracing panel  50   d  such that the two ground-engaging panels  210   a ,  210   b  are arranged in line with each other and that four standard apertures  256  of the additional bracing panel  219  will be co-located with four standard apertures  56  of the lowermost bracing panel  50   d  of the bracing sheet  220 . In this way an elongate unitary body is formed having four bracing panels and two ground-engaging panels  210   a ,  210   b . In use, the bracing sheet  220  will form an inverted T-shape, with each ground-engaging panel  210   a ,  210   b  lying flat along the ground and the bracing panels standing upright and orthogonal to the ground-engaging panels. 
     Referring now to  FIG. 21  in which like parts have been given the same reference numerals as before, there is shown an elongate bracing sheet  260 , having four bracing panels  62   a ,  62   b ,  62   c ,  62   d  and a ground-engaging panel  210   a , the bracing panels being delimited from each other by pairs of fold lines  64   a ,  64   b  and the ground-engaging panel  210   a  being delimited from the lowermost bracing panel  62   d  by a single fold line  264 . The fold lines are formed during the manufacture of the display unit  200 , and allow the substantially rigid material used to construct the display unit to fold easily at those lines. Each of the bracing panels  62   a ,  62   b ,  62   c ,  62   d  has a pair of crescent-shaped cut-outs  66  for engagement with elastic bands (not shown) thereby allowing the bracing sheet  220  to be connected to the display sheets  3 ,  5 . The points of the crescent-shaped cut-outs  66  face the edges of the bracing sheet  260  and effectively form notches for the reception of the elastic bands. The lowermost bracing panel  50   d  of the bracing sheet  260  has a pair of tabs  17  for engagement with the slots  15  on the display sheets  3 ,  5 . In this instance, the tabs are substantially rectangular in shape. The lowermost bracing panel  50   d  of the bracing sheet  2  further mounts the ground-engaging panel  210   a  which corresponds in shape to a segment of a circle, wherein its chord defines the base of the lowermost bracing panel  19   d  and extends beyond the width of the bracing sheet  260 . 
     Also shown in  FIG. 21  is a complementary panel  272  comprising the ground-engaging panel  210   b , which corresponds in shape and size to the ground-engaging panel  210   a  of the bracing sheet  260 . The complementary panel  272  further comprises a rectangular additional bracing panel  279 , delimited from the ground-engaging panel  210   b  by a crease line  280 , wherein the chord of the ground-engaging panel  210   b  defines the base of the additional bracing panel  279  and the crease line  280 . Furthermore the additional bracing panel  279  is the same width as the bracing panels  62   a ,  62   b ,  62   c ,  62   d  and comprises a pair of crescent shaped cut-outs  266  positioned such that when the two ground-engaging panels  210   a ,  210   b  are arranged in line with each other, the crescent shaped cut-outs  266  of the additional bracing panel  279  will be co-located with the crescent-shaped cut-outs  66  of the lowermost bracing panel  50   d  of the bracing sheet  260 . 
     To assemble the bracing sheet  260 , the complementary panel  272  is secured to the bracing panel  62   d  such that the two ground-engaging panels  210   a ,  210   b  are arranged in line with each other and that the crescent shaped cut-outs  266  of the additional bracing panel  279  will be co-located with the crescent-shaped cut-outs  66  of the lowermost bracing panel  62   d  of the bracing sheet  260 . In this way an elongate unitary body is formed having four bracing panels and two ground-engaging panels  210   a ,  210   b.    
     It will be understood that the embodiment of the display unit  200  described in relation to  FIGS. 15 to 21  use the same display sheet as described in relation to  FIGS. 1 to 7 . 
     Referring now to  FIG. 22 , in which like parts have been given the same reference numerals as before, there is shown a further embodiment of elongate bracing sheet indicated generally by the reference numeral  320 . The elongate bracing sheet is substantially similar to that illustrated in  FIG. 12  except that the uppermost bracing panel  350   a  is substantially rectangular in shape and is therefore substantially similar to the other bracing panels. Additionally, each of the upper three bracing panels  350   a ,  350   b ,  350   c  comprises a substantially rectangular cut-out  352   a ,  352   b ,  352   c  in the centre of the bracing panel. Such cutouts  352   a ,  352   b ,  352   c , when combined with similar cut-outs in the display panels, allow inserts such as shelving units or display elements to be placed in the display unit  1 ,  100 ,  200 . It will be noted that the use of such inserts is allowed by the use of a single bracing sheet having apertures  56  as described in relation to  FIGS. 5 ,  12  and  20 . 
     Referring now to  FIG. 23 , there is shown an alternative embodiment of display sheet, indicated generally by the reference numeral  370 . The display sheet  370  has a pair of display sheets  373 ,  375 , for use with the bracing sheet  320  of  FIG. 22 . The display sheets  373 ,  375  are shown as one piece. However, the skilled person will understand that by cutting along the line A-A, two identical display sheets can be made. The display sheets are substantially similar to those described in relation to  FIG. 6  except that each of the three uppermost panels  380   a ,  380   b ,  380   c ,  380   d  comprise substantially rectangular cut-outs  385   a ,  385   b ,  385   c  in the centre of the panel. This allows the insertion of various inserts which increase the functionality of the display unit. 
     It is envisaged that the arrangement of the bracing sheet  60 ,  160 ,  260  having crescent-shaped cut-outs  66 ,  266  located as described and shown in combination with the display sheets will provide a particularly effective self-expanding action for the display unit  1 ,  100 ,  200 . It is envisaged that the display unit will expand with increased speed, ease and reliability. 
     It will be understood that the bracing sheet is formed from a material of greater stiffness than the display sheet. This provides greater stability to the display unit. Furthermore this ensures that the force exerted on the bracing sheet by the elastic securing means will not cause the bracing sheet to bend. Preferably, the bracing sheet is manufactured from a stiff card such as corrugated cardboard, while the display sheets are manufactured from the less stiff material such as paperboard. 
     Ideally, there will be provided a pair of display sheets, each having a display surface. The display sheets may be made from a single sheet of material bended in half or from two separate pieces of material and this will depend largely on the limitations of the cutting equipment and the size of sheet that the cutting equipment is able to handle. The display sheets will be mounted back to back thereby forming an ellipse in horizontal cross-section and the bracing sheet will be located intermediate the two sheets. It is envisaged that the width of the bracing sheet will be of the order of between 70% and 90% of the width of the display sheet (that is, the width of the display face visible when in normal use and excluding any flaps  29  along the edges of the display face). Preferably, the width of the bracing sheet will be of the order of between 80% and 90% of the width of the display sheet. Ideally, the width of the bracing sheet will be of the order of between 82% and 88% of the width of the display sheet. Furthermore, the height of the bracing sheet at it maximum extension will be of the order of between 85% and 100% of the height of the display sheet. Preferably, the height of the bracing sheet will be of the order of between 90% and 100% of the height of the display sheet. Ideally, the height of the bracing sheet will be of the order of between 92% and 98% of the height of the display sheet. Typically, the display may be provided in a variety of sizes with different widths and heights to suit the individual needs. However, the display as shown in  FIGS. 1 to 7  has a display face with a height of the order of 153 cm and a display face width (when flat in a stored configuration) of 50 cm. The bracing sheets  2 ,  60  have a height at the edges (the common maximum point) of 145 cm and a maximum width (excluding the tabs  17 ) of 42 cm. The flaps  29  have a width of the order of 4.5 cm. 
     The presence of slots in both endmost panels of the display sheets makes the display sheets symmetrical. In other words, either end panel may be the top panel or the bottom panel and therefore the orientation of the panels relative to the bracing sheets during assembly is irrelevant. This reduces the complexity of the assembly process as it is not necessary to ensure that the display sheets are the right way up before commencing assembly. It will be understood that by altering the width of the bracing sheets relative to the display sheets, the curvature of the display sheets when the display unit is in use can also be altered. 
     Throughout the specification, the term elastic and elasticated has been used in reference to elements that return to their original shape or configuration after they have been deformed. It will be understood by the person skilled in the art that elements other than elastic bands could be used for this purpose. These elements could include springs and other resilient components. 
     In the specification the terms comprise, comprises, comprised and comprising or any variation thereof and the terms include, includes, included or including or any variation thereof are considered to be totally interchangeable and they should all be afforded the widest possible interpretation. 
     The invention is not limited to the embodiment herein described, but may be varied in both construction and detail within the terms of the claims.