EP0515459A1

EP0515459A1 - Display sign

Info

Publication number: EP0515459A1
Application number: EP19910903939
Authority: EP
Inventors: Michael Anthony Hobbs
Original assignee: AC Edwards PLC
Current assignee: AC Edwards PLC
Priority date: 1990-02-16
Filing date: 1991-02-14
Publication date: 1992-12-02
Also published as: PT96797A; AU7235391A; WO1991012604A1

Abstract

Une enseigne pour détaillants, du type à panneau-balançoire possède un cadre principal sous forme d'un moulage par injection à coeur gazeux, réalisé par exemple en polypropylène. Le coeur gazeux se présente comme une cavité simple qui s'étend le long du rail supérieur (1A), des montants latéraux (1B, 1C) et des parties extérieures du rail inférieur (1D) du cadre. Les régions creuses du cadre, vues en section transversale, sont convexes sur toute leur périphérie afin de faciliter le moulage et en particulier le centrage du coeur gazeux dans la structure moulée. La structure du cadre peut comporter des parties de connexion verticales pour des paires de pieds à pivotement (5) qui peuvent être déplacés depuis des positions perpendiculaires au cadre à des positions alignées avec les plans majeurs du cadre. L'utilisation d'un cadre de section généralement ovale ainsi que d'un rail inférieur (1D) qui n'est pas en contact avec le sol perment de disposer d'une structure qui résiste au renversement en cas de vents violents.A sign for retailers, of the swing panel type, has a main frame in the form of a gas-core injection molding, for example made of polypropylene. The gaseous core is presented as a simple cavity which extends along the upper rail (1A), lateral uprights (1B, 1C) and external parts of the lower rail (1D) of the frame. The hollow regions of the frame, seen in cross section, are convex over their entire periphery in order to facilitate molding and in particular the centering of the gaseous core in the molded structure. The frame structure may include vertical connecting portions for pairs of pivot feet (5) which can be moved from positions perpendicular to the frame to positions aligned with the major planes of the frame. The use of a frame of generally oval section as well as of a lower rail (1D) which is not in contact with the ground makes it possible to have a structure which resists overturning in the event of strong winds.

Description

DISPLAY SIGN

The present invention relates to a display sign, particularly one that has a sturdy and attractive appearance and can be used out of doors in heavy wind.

As is well known, retailers frequently want to advertise their products to passers-by by means of pavement signs. Such signs are desirably lightweight in order that they may be portable; and they need to have an attractive appearance less they detract from the message being presented. Many existing pavement signs are constructed of painted tubular metal (see GB-B-2112988 and GB-B-2155680). However, it is not practical to make tubular metal signs having tubing of non-circular cross section because of the problem in bending non-circular tubes to the required shape and this places a restriction on the freedom of the designer to select different sections for the frame of the sign. The paint on the tubular metal frames is also a problem because accident damage can cause the paint to chip off and bare metal to show. Many existing signs of the type having swinging panels supported in a ground-contacting frame are easily blown over. There are two causes for this which are firstly that the height of the sign is greater than its base dimensions because of the requirment to display a generally rectangular swinging panel with' its longer dimension vertical and secondly that the swinging panel is supported from the top of the sign and the panel therefore applies a higher turning moment to the frame in a wind.

Plastics materials have the advantage of being easily made self-coloured and are inexpensive to mould but they have not been used in pavement signs for the main or panel-supporting frame structure because they are difficult to make in the required dimensions, stiffness and torsional resistance, because there are problems of weight distribution, and because there are problems in making a unitary mould of the right size and properties. A further difficulty is in making the frame everywhere of the required mechanical strength, and in particular with sufficient fatigue strength to avoid cracks developing in the surface, and also there is a need to select a material that does not become brittle at low temperatures and hence liable to crack damage either as a result of accident or as a result of vandalism in icy conditions.

We have now found that a main frame for a display sign can be made as a single gas-cored moulding in plastics material, the gas core extending along a major proportion of or substantially the whole of the frame.

In one aspect, therefore, the invention provides a display sign comprising a ground-contacting base or feet, a frame upstanding from the base or feet, and a display panel supported by the frame, wherein the frame is of a plastics material which for a major part of the periphery of the frame (a) presents an unbroken outer surface, and (b) when viewed in section is void-free only adjacent its outer surface.

The invention also provides a method for making a frame for a display sign from a polymeric material, which comprises injecting the polymer into a mould together with a fluid that causes the polymer material of the frame to be hollow. Preferably a major part of the periphery of the frame is tubular and preferably it is also of non-circular cross section. In the latter case, the frame when viewed in section preferably has a dimension in its major direction that is from one 1.5 to 3 times its dimension in the minor direction, the major direction being at right angles to the plane of the display panel.

In this case, the longer direction of the frame is aligned in that direction in which a high wind resistance is to be most avoided which is a direction generally perpendicular to the plane of the display panel. We have found that significantly higher wind speeds can be tolerated when using a frame of generally oval cross section. The word "oval" is used here in the a general sense to include not only a regular ellipse but also an egg-shape, shapes in which there is a straight parallel sided central region and rounded ends, or a symmetrical shape having continuous convexity about its periphery with gently radiused or curved sides and sharply radiused or curved ends. It is preferred, however, that the tubular parts of the frame when viewed in transverse section are convex throughout the whole of their periphery because this convexity assists in ^'- 5 - positioning the frame tube within the mould cavity and tends to center the gas core within the mould so as to avoid the development of regions of local wall thinness during moulding that could give rise to inadequate strength and cracking in the finished frame. A shape having curved sides and curved ends defining two pairs of differently curved regions with the radius of curvature of the sides being e.g. 3.8 and preferably about 5 times the radius of curvature of the ends may conveniently be adopted and give an attractive appearance.

The frame is preferably substantially rectangular with rounded corners (radius e.g. 100mm in a typical frame) and is arranged with its long side vertical.

Thus the frame structure is made up of a top rail, two

• side posts and a bottom rail all joined together to form a unitary structure. The hollow space or gas core within the frame is preferably continuous and extends along the whole of the top rail, down the side posts and along outer regions of the bottom rail towards the centre thereof. A short central region of the bottom rail is of non-tubular structure and is of arcuate or aerofoil-like cross section. The frame is preferably formed at its lower corners with integral depending formations for attachment to the frame of the ground-contacting base or feet and the internal void or gas core of the frame preferably extends from the side posts into these depending formations. The depending formations are preferably larger in their cross-sectional dimensions than the frame side posts both to accomodate the means that fastens the frame to the base or legs and also to resist the torsional and other loads transmitted from the frame into the base, and they are tapered smoothly into the side posts to avoid development of local stress concentrations.

It is surprising that such a large frame structure having a non-linear cavity can be formed by gas-cored injection moulding and that the internal cavity that defines the core can be made of such a substantial volume, of such substantial area and length. Thus the internal cavity can be made to extend along the top rail, to extend around the two corners necessary to lead it into side posts and further extend around the two corners that lead it into the bottom rail, and that during this process no regions of local thinness develop which could lead to local material deficiency in the finished moulding and hence cracking thereof in the service. The continuously convexly curved section of the frame referred to above is believed to assist in centering the gas core within the plastics moulding and hence contributes to the avoidance of such regions of material deficiency. The ability to achieve continuation of the core beyond enlarged spaces where the depending formations join the bottom rail is also a surprising feature of the invention.

The sign may be provided with ground contacting feet provided with upstanding spigots, and the depending formations may have sockets in which the spigots on the feet are received. The feet conveniently occur in pairs with each foot being less than half the width of the frame, and the feet may be rotatable between a first position where they are substantially parallel to the plane of the frame and a second position where they are substantially perpendicular to or are oblique to the plane of the frame. Biassing means preferably position the feet preferentially in their first and/or second positions. This biassing means is associated with each foot and comprises a spring loaded detent in one of the spigot and socket and a recess in the other of the spigot and socket at each of the two positions, so that the detent is forced out of the recess against the bias as the foot is rotated from each of the first and second positions. The foot may also be tubular and moulded in plastics material and it may have a ballast core of relatively dense material e.g. concrete present in the internal space of the tube. In that case the free end of each foot is covered by a cap which conceals and retains the core.

The frame preferably includes a top rail parallel to the ground and the display panel is a sheet that is attached to the frame only by a pivotal suspension from the top rail. The top rail may have on its lower face at least two formation spaced apart therealong each having an aperture extending therethrough directed normal to the top rail. The display panel will normally then be suspended from the top rail by means of at least two straps that pass through apertures adjacent to the top edge of the panel and that are received in apertures extending through the formations, though any other known pivoted suspension for a swinging panel may be used instead is so desired. The swinging panel may be pivotted to vertical sides of the frame partway towards the top of the frame with a fixed infill panel above it. Alternatively it may be pivotted at a central position to top and bottom rails of the frame so as to be free to revolve.

In the case of a rectangular framed sign it is preferred that the base or foot structure should support the frame with its lower rail at a clearance from the ground, thereby decreasing the effective wind resistance of the frame by providing an air passage underneath the lower rail.

The sign may be of any convenient size, but we have found that it is particularly useful in connection with signs having display panels that are approximately A-l in size. The resulting frames are generally rectangular with short sides from 30 to 90, and especially 50 to 70 cm in length and long sides from 40 to 160 especially 70 to 90 cm in length. The display panel may conveniently be a sheet of aluminum or other suitable metal which may be printed or otherwise provided with a design. The panel may be suspended by means of straps that pass through upper slots in the panel and are secured to a top rail of the frame. Opposite ends of the strap may be secured together and retained within strap-retaining means on the underside of the top rail which can conceal the ends of the strap and give the strap the appearance of a continous band. The frame may be made by a variety of methods but it is much preferred that it be moulded e.g. by foaming in situ using a blowing agent or more preferably by gas injection. Preferred moulding techniques include blow and injection moulding and in particular gas-core injection moulding. In this latter process a fluid e.g. a gas such as nitrogen is introduced through a sprue into the mould. In alternative methods, gas can be introduced into the component in more than one location through a sprue or it may be introduced directly into the component either in one position or in multiple positions. Introduction of such a gas drives the moulding material outwards to the surface of the mould leaving a passage or core through the middle and resulting in a hollow structure. Preferably the gas injection is began shortly after polymer injection is began. A moulding technique of this type that is known by the trade mark "CINPRES" and is available from Cinpres Limited, Apollo, Lichfield Road Industrial Estate, Tamworth, Staffordshire BA79 7TA, England. The process is described, for example, in US Patent Nos 4824732, 4740150 and 4489860 and in many of the references cited therein, the disclosures of which are incorporated herein by reference. A variety of moulding materials may be used of which polypropylene is preferred. The material may be mixed with a filler such as from 15 to 45% preferably 35 to 42% by weight, based on the weight of the moulding material, of an inert filler such as chalk or talc. Preferably, however, the moulding material is an unfilled grade of polypropylene or other polymer pigmented with e.g. titanium dioxide and containing an anti-static additive, a UV stabiliser and a nucleating agent to equalise the grain size of the polymer in different parts of its section as moulded frame cools. The polymer should be selected to have a suitable low temperature performance e.g. its secondary glass

transition temperature should not be above -20 C in order that the polymer should not be converted into a brittle phase at any temperature in which it is likely to encounter in its external environment. A suitable material is an unreinforced block co-polymer of polypropylene with ethylene available under the trade name NOVOLENE 2000 grade 2340Px which contains a nucleating agent, from BASF AG. The preferred grade has a melt flow index of about 15 measured according

to the test procedure in ISO 1133 or DIN 5375 at 230°C and a load of about 2.16 kilograms. The invention also provides a portable outdoor sign assembly comprising a unitary substantially vertical frame having a transverse member at its top and vertical sockets (generally two pairs) at the bottom respectively on opposite sides of the frame, L-shaped support members (generally four) respectively allocated to the sockets with substantially vertical limbs rotatable or otherwise movable in the sockets and feet projecting perpendicular to the limbs, so that each foot can either be positioned substantially perpendicular to the plane of the frame or parallel to the plane, means optionally being concealed in each socket for automatically locking the associated support member in each of the at least two positions and a sign panel extending from the transverse top member, preferably allowing it to swing backwards and forwards therefrom.

The invention will now be further described, by way of example only with reference to the accompanying drawings in which:

Figure 1 is a perspective view of a sign assembly with its feet extended; Figure 2 is a view similar to figure 1 but showing the feet folded away;

Figures 3 and 4 are respectively a front elevation and a plan of the assembly of figure 1;

Figure 5 is cross section of a lower part of the frame showing a detail of one of the legs on which the frame stands and a socket in which it is received;

Figure 6 is an elevation on an enlarged scale of a top part of the assembly of Figures 1 to 4;

Figure 7 is a plan view of a strap by which the swinging display panel is attached to the frame of the sign assembly;

Figure 8 is an elevation of the strap of figure 7;

Figures 9A and 9B are an elevation and view from below of a preferred frame, figures 9C and 9D are cross sections on the lines C-C and D-D respectively of figure 9A and figures 9E and 9F are respectively a scrap underneath view and a section on the line E-E of figure 9E of a second form of lower rail forming part of the frame; Figures 10A and 10B are a cross section and a view from below of sockets at the base of a frame similar to that shown in figure 9;

Figure 11 shows a support member that fits into a socket of figure 10; and

Figure 12 is a diagram of a mould cavity.

The sign assembly shown in the drawings comprises a frame 1 within which a display panel 2 is suspended so as to be able to swing backwards and forwards relative to the frame. The frame 1 is a hollow 1-piece moulding in plastics material and is generally rectangular with rounded corners. At its lower corners there are provided depending or downwardly facing substantially vertical sockets 3, two in tandem on each side, in each of which are mounted four similar L-shaped or other support members 4 each comprising a substantially horizontal foot 5 and a substantially vertical limb 6 (see Figure 11). The support members fit into the sockets 3 and can be rotated about substantially vertical axes thereof. Thus each support member 4 can be rotated in a substantially horizontal plane between a position in which the foot projects outwards as shown in Figure 1 and a folded position shown in Figure 2.

The frame structure is shown in more detail in figures 9A to 9D and is a moulding in polypropylene homopolymer or copolymer as aforesaid. A suitable polymer is NOVOLENE 2000 unreinforced block copolymer of polypropylene with ethylene as aforesaid. The overall height of the frame is about 820mm and its overall width is about 600mm giving an aspect ratio of about 1.3 - 1.4. The ratio of the radius of curvature of the corners to the shorter dimension of the frame is about 1:0.14 and ratios of from 1:0.1 to 1:0.2 are conveniently used for ease of moulding and attractiveness of appearance. The section of the frame is shown in Figures 9C and 9D from which it is apparent that the external surface of the tubular parts of the frame are formed by continuous convex curves, the curvature being relatively slight at the sides of the section and relatively sharp at the ends of the section as shown. The major dimension of the frame when viewed in transverse section is 54mm and the minor dimension is 27mm. The external apparently oval shape may be formed from two opposite pairs of curved regions smoothly joined to one another, the side regions having e.g. a 54mm radius of curvature and the end regions have e.g. 10mm radius of curvature. The tubular parts of the frame have a single generally oval internal cavity which substantially coincides with the external shape of the frame and defines therewith a relatively thick wall tube, the wall thickness being greatest adjacent the sharply curved ends of the frame and least adjacent the less steeply curving sides of the frame. In the embodiment shown the wall thickness is adjacent the ends is about 0.75cm and the wall thickness in the middle of the sides is 0.3cm. This wall thickness may vary depending upon the particular material from which the section is moulded, and could be, for example, from 0.15-0.5cm at the short axes to 0.5 to 1cm at the long axes.

The frame structure comprises a top rail 1A, side posts IB and 1C and a bottom rail ID as shown. The posts and rails of the frame have a single continuous cavity which extends the length of the top rail 1A, down the side posts IB and 1C and inwardly partway across the bottom rail ID, where it appears marked 24 in the lower left hand corner of figure 9A. A central region 21 of the rail ID is of hollow open form rather than tubular form as shown by reference number 22, the region 21 presenting a smoothly curved top surface which is continuous with the top surfaces of the tubular region and an open lower surface as shown. As will be explained below, the polymer material from which the frame is moulded is injected into the mould cavity at the mid point of top rail 1A, flows down cavities defining the side posts IB and 1C and meets again midway along the cavity defining the bottom rail ID. There is a tendency for weakness to develop where the two oppositely flowing streams of polymer meet, which happens in the region 21 of the lower rail ID, and in order to avoid such potential weakness having a harmful effect on the mechanical properties of the frame, the hollow underneath region 22 of the rail ID can be reinforced with one or more moulded-in longitudinal or transverse reinforcing ribs (not shown).

A second form of lower rail structure is shown in figure 9E and figure 9F. As is apparent from figure 9E the open downwardly facing region 22A at the underside of the lower rail ID is made smaller to provide a pair of relatively thick walls 40, 41 bounding the space 22A which overlap one another at the knit line 28 (see also fig 12) and lead into thinner downwardly facing wall portions 42 and 43. Each relatively thick region 40, 41 may be formed with a gas core 44, 45 which is a continuation of the respective gas core 24 at the respective outer portion of the lower rail IB. The cavities 44, 45 may extend beyond the knit line 28 so that they overlap, or they may extend only partway along each of the thick wall portions 40, 41 terminating short of the knit line 28. The walls 40, 41 provide overlapping tubular reinforcing regions adjacent the knit line 28 which serve to resist cracking adjacent to the knit line.

The frame is also formed with depending socket formations 25 that originate where the posts IB, 1C meet the bottom rail ID and face downwardly as shown, extending below the bottom rail ID. The socket formations 25 are of larger size than the side posts IB, 1C of which they otherwise appear to be a smooth continuation, and this both serves to define the pairs of tandem sockets 3 and also to provide adequate mechanical strength at the junction between the frame 1 and the support members 5 so that undue stress concentrations leading to cracking of the frame do not arise where the upper frame 1 is joined to the support members 4. As is best seen in Figure 10A the internal hollow space or air core 24 of the frame 1 extends downwardly from the side post IB into the relatively thick junction region between the post IB and the - 19 - socket formation 25 and actually into a region 24A between the walls of the sockets 3. The ability to form relatively large regions of the internal space 24 where the posts IB join the socket formations 25 and at the same time to form the cavity 24 at the outer ends of the bottom rail ID which is generally the same size as the internal cavity elsewhere in the frame is a further surprising feature of the invention.

Figure 12 is a diagram of the mould cavity in which the movement of the plastics material and gas being injected into the mould is indicated diagrammatically by arrows. The polymer and gas are injected into a sprue 27 leading to the blind or underside of a region 30A of the mould cavity to form the top rail 1A. The polymer and gas streams then split to left and right as shown to travel through regions of the mould cavity defining the top corners of the frame and through regions 30B, 30C defining the side posts of the frame. At locations defining the lower corners of the frame the flow of gas and polymer split, part of it going into a region 30D of the mould cavity defining the lower rail where the two now convergent streams meet at a knit line 28 where the polymer stream become bonded together. A gas vent (not shown) may be provided at the line 28. The remainder of the polymer and gas at the lower ends of the posts 30B and 30C flow into regions 30E of the mould cavity defining the socket regions 25. Thus there is effectively in the region of each of the two socket regions 25 a bulb of plastic of enlarged diameter into which the internal cavity of substantially constant cross section leads and from which an extension of the constant cross-section cavity extends to define the region of the internal cavity 24 within the lower rail 30D.

The frame 1 is supported by two pairs of support members 4, each pair of the support members 4 facing away from one of the two opposite faces of the frame 1. Each support member 4 comprises a vertical limb 6 and a hollow foot 5. The vertical limb 6 has in it an arcuate groove 13A for receiving pin 13 to retain the limb 6 in the socket 3. Each foot 5 of the support member is weighted by means of a filling of concrete, cement, metal or other ballast. Where concrete or other settable ballast is used, it may be inserted into the foot 5 and allowed to set in situ, or it may be pre-cast in a shape complementary to the internal shape of the foot 5 and introduced as a preformed component into the foot 5. The free end of each foot 5 has projections or other means that serve to retain a cap of rubber or other suitable material that both can conceal and serves to retain the ballast within the leg. A projecting rib is provided adjacent each of the connections which serves to deflect obstructions on the fjoor from the cap of rubber or other suitable material and assists in preventing the cap from being forced off..

Each support member 4 may be latched in each of its supporting and folded positons by a mechanism that may be completely concealed within the respective socket 3. A preferred mechanism is shown in Figure 5 from which it is apparent that the socket 3 is formed with two arcuate recesses 7 spaced apart by 90 degrees about the socket axis. The 90 degree angle is not critical, and other angles may be chosen, however, since the legs 5 need not extend perpendicular to the panel 2 in order to provide the required support for the frame 1. The limb 6 of the support member may be hollow and may contain a diametral bearing 8 for a reciprocal detent member 9 having a head 10 that fits into each recess 7. When the foot 5 is moved from one of its stable positions to another, rotation of the limb 6 causes the head 10 to be cammed out of whichever recess 7 it then occupies. This depresses detent member 9 against the bias of leaf spring 11. The spring 11 may be retained by, for example, ledges or other support 12 located within the limb 6. The head 10 can slide over the socket wall and when it reaches a recess, the spring 11 returns the detent member 9 to its latching position. Each limb 6 may be retained in its socket 3 by means such as a permanently or otherwise secured pin as shown at 13 in Figure 3. The pin 13 may project into an arcuate groove 13A (Fig 11) in the limb 6, the groove 13A having sufficient ambit to allow the desired rotation of the limb.

The display panel 2 may be made of any suitable rigid material capable of withstanding outdoor conditions. Preferably the panel 2 is of a material that can be readily printed with information to be displayed, and the use of a flat aluminum sheet is preferred because it is readily screen printable. The panel 2 is in this form of the sign formed with a pair of slots 15 adjacent its upper edge through which straps 14 are passed, the straps entering passages 16 (Fig 6) in formations depending from a lower face of the top rail 1A. The ends of each strap 14 have complementary integrally formed latch members 17 as shown in figure 7. When the ends of the strap are inserted into opposite ends of the passges 16 (i.e. from opposite sides of the frame) planar upper regions of the strap 14 in which the latch members 17 are formed are held against the top of the passage 16 by ribs 18 upstanding from the lower part of the formations defining the passages 16.

When the ends of the strap 14 are pushed into the passage 16 from opposite ends thereof, the inclined surfaces 19 slide over one another until the abutment surfaces 20 of the respective latch members 17 pass one another, after which the latching members are engaged with one another to prevent the ends of the strap from being pulled out of the passage 16 and to allow the strap 14 to take the weight of the panel 2. The passage 16 has to be wider than the strap 17 to allow the two latch members 17 to move past one another and then snap home into their latching position. The resulting connection can be released by forcing the ends of the strap laterally apart so that the surfaces 20 are no longer in abutment with one another, or alternatively the strap can simply be cut, removed and replaced by a fresh strap when it is desired to change the display panel suspended from the frame. An advantage of the above strap structure is that the joint in the strap is concealed giving a neat appearance. A frame as illustrated has been subjected to wind-tunnel tests in a 15 foot (457cm) wind tunnel. The frame as previously stated was generally rectangular with an outside size of 60cm (horizontal) by about 80cm (vertical) with rounded corners, the frame being supported on four concrete-filled support members of length about 15cm. Two of the support members 4 extend perpendicular to the frame at each end of the lower rail ID, one in each direction. The support member 4 held the lower rail ID about 7cm above the ground. The frame was provided with a substantially rigid panel 2 pivotally connected as to its horizontal edges so that it could swing. The panel size was about 50cm by 72cm, leaving a gap of about 2.5cm between the panel and the inner edges of the frame (in general a gap of from 1 to 5cm is sufficient). The above sign withstood wind speeds of 60mph (96kph), with some rocking at speeds over 40mph (64kph). Prior art signs of similar size toppled at about 33mph (53kph).

Various modifications to the embodiment described above may be made without departing from the invention. For example, the outline of the frame could be similar to the outline of the Ultrasign display sign made by A C Edwards PLC (see GB-B-2155680). In case the main frame structure of the sign is generally C-shaped and the main frame is connected to a ground contacting base which in Ultrasign and signs of similar appearance is in the shape of a rectangle with rounded corners. In Ultrasign itself the base is formed in two halves to either side of the main frame which may be rotated downwardly to bring the two halves of the base into substantially the same plane as the main frame for storage thereof. In less expensive variants of Ultrasign made by third parties there is provided a single rectangular frame with rounded corners without the ability to fold, an inverted U-shaped main frame being simply welded to the ground contacting base. Versions of both forms of this display sign could be made with the main frame and optionally the base moulded in plastics material so as to form gas-cored structures.

The inverted U-shaped main frame structure would be relatively simple to mould as an air-core moulding with the core extending along the whole length of the frame and with integral fastening formations at the end of the U for attachment to the base. There would be no need in this structure to provide a fourth cross limb or lower rail because the dimensional stabillity at the ends of the U-shaped main frame is provided by attachment of the frame to the base itself which is a rigid structure not prone to dimensional change widthwise of the sign. A retail display sign generally similar to the SWINGSIGN (patent number GB-B-2112988) with an open frame could also be provided as a one piece gas cored moulding in plastics and because of the inherent flexibility of plastics compared to metal it is possible that the sign could be constructed with the ability to be erected and collapsed without the need for the slit along the underside of the top rail that is present SWINGSIGN. Other shapes of display sign having gas cored moulded frames e.g. so called A-boards will be apparent to those skilled in the retail display sign art.

Claims

1. A display sign comprising a ground contacting base or feet, a frame upstanding from the base or feet, and a display panel supported by the frame, wherein the frame is of plastics material which for a major part of the periphery of the frame (a) presents an unbroken outer surface, and (b) when viewed in section is void-free only adjacent its outer surface.

2. A display sign according to claim 1, wherein the major part of the periphery of the frame is tubular.

3. A display sign according to claim 1 or 2, wherein the major part of the periphery of the frame is of non-circular cross section.

4. A display sign according to claim 3 which when viewed in section has a dimension in its major direction that is from 1.5 to 3 times its dimension in the minor direction.

5. A display sign according to claim 4, wherein the major direction is at right angles to the plane of the display panel.

6. A display sign according to any preceding claim, in which a major part of the periphery of the frame is oval when viewed in cross section.

7. A display sign according to any preceding claim, wherein the frame is closed and lies in a single plane.

8. A display sign according to claim 7, wherein the frame is generally rectangular with rounded corners.

9. A display sign according to claim 8, wherein the height of the frame is greater than its width.

10. A display sign according to claim 8 or 9, where each lower corner of the frame has an integral depending formation for attachment to the frame of the ground-contacting base or feet.

11. A display sign according to claim 10, wherein the depending formations have internal voids.

12. A display sign according to claim 10 or 11, wherein the sign has ground contacting feet provided with upstanding spigots, and the depending formations have sockets in which the spigots on the feet are received.

13. A display sign according to claim 12, wherein the feet occur in pairs each foot being less than half the width of the frame, and the feet are rotatable between a first position where there are substantially parallel to the plane of the frame and a second position where they ere substantially perpendicular to or are oblique to the plane of the frame.

14. A sign according to claim 13, further comprising biassing means for positioning the feet preferentially in their first and/or second positions.

15. A display sign according to claim 14, wherein biassing means associated with each foot comprises a spring loaded detent in one of the spigot and the socket and a recess in the other of the spigot and the socket at each of two positions so that the detent is forced out of the recess against the bias as the foot is rotated from each of the first and second positions.

16. A display sign according to any preceding claim, wherein the ground-contacting portion of each foot is in the form of tube, and a core of a relatively dense material is present in the internal space of the tube.

17. A display sign according to claim 16, wherein the free end of each foot is covered by a cap for concealing and retaining the core.

18. A sign according to any of claims 13 to 17, wherein the feet are of a plastics material, cast iron or cast aluminium.

19. A display sign according to any preceding claim, wherein the frame includes a top rail parallel to the ground, and the display panel is a sheet that is attached to the frame only by pivotal suspension from the top rail.

20. A display sign according to claim 19, wherein the top rail has on its lower face at least two formations spaced apart therealong and each having an aperture extending therethrough directed normal to the top rail, and the display panel is suspended from the top rail by means of at least two straps that pass through apertures adjacent to the top edge of the panel and are received in the apertures extending through the formations.

21. A display sign according to any preceding claim, wherein the display panel is approximately A-l size.

22. A display sign comprising a ground contacting base or feet, a frame upstanding from the base or feet, and a display panel supported by the frame, wherein the frame is of plastics material and is a gas-cored injection moulding, the hollow core extending along a major part of the periphery of the frame.

23. A display sign according to claim 22, wherein the frame is generally rectangular with rounded corners when viewed in elevation to define a top rail, side rails and a bottom rail, and the gas core extends continuously along the top rail, the side rails and into part of the bottom rail.

24. A display sign according to any preceding claim, in which the frame comprises polypropylene or a copolymer thereof.

25. A display sign according to claim 24, in which the frame comprises polypropylene filled with from 15 to 25% by weight, based on the weight of the polypropylene of a filler.

26. A sign according to claim 25, wherein the filler is chalk.

27. A display sign according to any preceding claim wherein the polymer of the frame has a glass

transition temperature of not more than -20 C.

28. A display sign according to any preceding claim where the polymer has a melt index of about 15

measured according to DIN53735 at 230°C under a load of 2.16Kg.

29. A method of making a polymeric frame for a display sign, which comprises injected a polymer into a mould together with a fluid that causes the polymeric frame to be hollow.