"System and method for retaining a flexible sheet"

The present invention relates to a system and method for retaining a flexible sheet, especially but not exclusively for installing a large advertising sign or banner on a static site, such as a building, or an advertising hoarding, such as those seen by road sides.

Conventional roadside signs or advertisements comprise a number of sheets, which are glued together in sequence on a billboard. For different billboards, different numbers of sheets are used, but these typically range from six sheets to ninety-six sheets; a ninety-six sheet panel is typically 13 metres in horizontal width.

Such signs are inconvenient and time-consuming to install, and require one or more persons with ladders (the top of the billboard may be 6 metres high, for example). Also, when the sign needs to be changed, the original sign either has to be removed, or a new sign glued over it. When the old sign is removed, as it is covered in glue, it cannot be easily or fully recycled.

One possible alternative to gluing the sign to the billboard includes first making the sign, and then "finishing" it such that it can be attached to a frame mounted on the billboard. One way of doing this is to add edge strips to all four edges of the sign. The edge strips can include cylindrical protrusions, which can then be threaded into corresponding recesses in the frame, which is mounted on the billboard. This means that the sign can be installed on the billboard more easily, and also taken down, when it is needed to be replaced. However, this system requires both the sign to be specially "finished" at the creation stage by adding the edge strip, and the mounting requires people on ladders, so that they can be elevated to

the height of the top of the billboard, in order to thread the protrusion into the frame. Furthermore, an old sign cannot be easily or completely recycled, because the edge strip would first have to be removed.

According to a first aspect of the present invention there is provided a system for retaining a flexible sheet comprising: a support structure comprising at least one longitudinally extending channel provided with an inwardly extending detent; and at least one longitudinally extending insert member provided with an outwardly extending barb, the insert member being adapted to engage within the channel; wherein the barb and detent are formed so that, when a flexible sheet is interposed between the channel and insert member and the insert member is engaged within the channel, the barb is engaged behind the detent, to frictionally engage the flexible sheet between the channel and the insert member.

Optionally, the channel is generally U-shaped in cross-section, and the inwardly extending detent extends inwardly into the channel from one side wall of the channel in a direction towards the other side wall.

The detent may extend continuously along the full length of the side wall of the channel. Alternatively, a plurality of discrete detents may be distributed along the full length of the side wall of the channel.

Typically the channel forms part of a frame for the flexible sheet, and the channel is arranged on the support structure such that the detent is on the outermost side wall with respect to the frame.

Optionally, the system comprises at least two channels and at least one respective insert member per channel. Optionally, the system comprises four channels and at least one respective insert member per channel.

Typically, more than one insert member is provided for the or each channel.

A plurality of inserts members may be attached to each channel in pre- insertion positions. The insert members may be provided in a variety of lengths.

Optionally, the at least one channel is provided on a rail attached to the support structure.

Typically, the at least one insert member is releasably engageable within the or each channel.

Typically, the insert member is releasably engageable within the channel by means of a snap-fit arrangement.

Optionally, at least one property of the insert member is selected such that the insert member is relatively more resiliently deformable than the channel to facilitate the snap-fit arrangement, the at least one property being selected from the group consisting of: the shape of the insert member; the dimensions of the insert member; and the material from which the insert member is formed.

Typically, the insert member is generally U-shaped in cross-section and comprises two side walls, one of which is inclined relative to the other.

Optionally, the outwardly extending barb is provided on one of the inclined side walls.

The barb may extend continuously along the full length of the inclined side wall of the insert member. Alternatively, a plurality of discrete barbs may be distributed along the full length of the inclined side wall of the insert member.

According to a second aspect of the present invention, there is provided an assembly comprising: a system as claimed in any preceding claim; and a flexible sheet.

Typically, the flexible sheet has no peripheral finishing to facilitate its engagement with the channel.

Optionally, the flexible sheet comprises a sign. Optionally, the sign comprises an advertising sign.

The sign may comprise a sheet of printable material, for example polyethylene although any suitable sheet material may be used. Preferably, the material is recyclable.

Optionally, the entire flexible sheet is recyclable.

Typically, the insert member is independent of the flexible sheet.

According to a third aspect of the invention there is provided a method for retaining a flexible sheet comprising the steps of:

providing a longitudinally extending channel provided with an inwardly extending detent; providing a longitudinally extending insert member provided with an outwardly extending barb; interposing a flexible sheet between the channel and insert member respectively; and inserting the insert member within the channel such that the barb snaps into position behind the detent to fhctionally engage the flexible sheet between the channel and the insert member.

Typically, the step of inserting the insert member within the channel tensions the flexible sheet by pushing part of the flexible sheet into the channel.

Typically, the step of interposing the flexible sheet between the channel and the insert member comprises interposing a peripheral region of the flexible sheet.

Optionally, a plurality of insert members are inserted into the channel, along the length of the channel, and wherein the steps of inserting the insert members involve first inserting an insert member in a substantially central position within the channel and progressively inserting further insert members in stages in both directions towards the respective distal ends of the channel.

The further insert members may be shorter than the first, central, insert member.

Optionally, the step of progressively inserting the further insert members in both directions towards the respective distal ends of the channel involves progressively manually tensioning the sign prior to each insertion.

Alternatively, a plurality of insert members are inserted into the channel, along the length of the channel, and the steps of inserting the insert members involve firstly positioning three relatively short insert members at a central position and both distal ends of the channel, and then filling in the gaps with further, longer, insert members.

An embodiment of the invention will now be described, by way of example only, and with reference to the following drawings, in which:-

Fig 1 shows a perspective view of a support structure having four longitudinally extending rails mounted thereon: an upper rail, a lower rail and left and right side rails, each of which has a longitudinally extending channel;

Fig 2 shows a perspective view of the support structure of Fig 1 , having the four longitudinally extending rails in an alternative arrangement;

Fig 3 shows a partial perspective view of the upper rail of Fig 1 and a longitudinally extending insert member;

Fig 4 shows a sectional view of the upper rail and the longitudinally extending insert member of Fig 3, with an advertising sign interposed therebetween, prior to engagement of the insert member within a channel of the upper rail;

Fig 5 shows a sectional view of the upper rail and the insert member of Figs 3 and 4, with the advertising sign frictionally engaged between the insert member and the upper rail;

Fig 6 shows a sectional view of the lower rail of Fig 1 and a respective longitudinally extending insert member; and

Fig 7 shows a sectional view corresponding to Fig 6 of a similar embodiment, also including a hinged cover.

Referring now to Fig 1 , an upper rail 10, a lower rail 12, a left side rail 14 and a right side rail 16 are mounted on a support structure. The support structure can be a board of any suitable material, such as plywood or MDF, mounted to an existing structure such as a building or wall, or it can be an independent structure, such as a billboard hoarding, a mobile trailer or the like. In this embodiment, the support structure comprises a billboard 18.

The rails 10, 12, 14, 16 are arranged so that they form a rectangular frame on the billboard 18, with the top rail 10 forming the top edge of the frame, etc. The frame is suitable for displaying a flexible sheet, typically at the side of a road or railway, etc., as will be described. The flexible sheet may comprise a sign, such as an advertising sign.

The rails 10, 12, 14, 16 may be of uPVC, aluminium, alloy or any other suitable material, and are preferably formed by extrusion. The rails 10, 12, 14, 16 are fixed to the billboard 18 by any suitable fastening means, such as bolts, screws, adhesive, nails or the like (not shown). Although they are shown as continuous members, they may be formed from separate components which are joined together.

Fig 2 shows a very similar embodiment to Fig 1 , and like parts have the same reference numbers. The only difference is the arrangement of the rails 10, 12, 14, 16. In Fig 1 , the left and right side rails 14, 16 are located just beyond the ends of the upper and lower rails 10, 12, leaving gaps at the four corners of the frame. However, in Fig 2, the left and right side rails 14, 16 are located between respective ends of the upper and lower rails 10, 12, so that the frame is closed. Please note that Figs 1 and 2 are schematic only and are not to scale.

Figs 3 to 5 show the upper rail 10 in more detail. The other rails 12, 14, 16 are identical to the upper rail 10.

The upper rail 10 comprises a top longitudinally extending channel 258. The channel 258 is generally U-shaped and symmetrical in cross-section and is defined by a generally planar base wall 252a and two opposing generally planar side walls 252b, 252c each extending substantially perpendicularly from the base wall 252a.

An inwardly projecting detent 270 is provided on one side wall 252b and projects into the channel 258 towards the opposing side wall 252c from a position remote from the base wall 252a. The detent 270 therefore serves to narrow the entry of the channel 258.

The inwardly projecting detent 270 is on the uppermost side of the upper rail 10, as shown in Figs 1 to 5. Therefore, with respect to the frame formed by the four rails 10, 12, 14, 16, the detent 270 is on the outermost side wall of the channel 258.

The detent 270 is provided with an inclined surface 270a which facilitates the insertion of a longitudinally extending insert member 300 into the channel 258 as described further below. The insert member 300 is also generally U-shaped in cross-section and is provided with two side walls 352b, 352c. One of the side walls 352b is provided with a ramp surface 352d which is inclined relative to the other side wall 352c. The respective side walls 352b, 352c converge at a position which is offset towards the side wall 352c such that the insert member 300 is asymmetric in cross- section.

The ramp portion 352d of side wall 352b terminates in an outwardly extending barb 352e the function of which is described below. Outwardly directed sign engaging flanges 360a, 360b are provided at the distal ends of each side wall 352b, 352c. The barb 352e and flange 360a define a recessed portion 370 which is dimensioned to accommodate the detent 270 of the upper rail 10 as described below.

The upper rail 10 and its detent 270 are formed, preferably by extrusion, as one integral piece. The upper rail 10 is typically aluminium. However, it will be appreciated that other suitable materials may equally be employed, for example, uPVC or a different plastics material or alloy.

Similarly, the insert member 300 and its barb 352e are formed, preferably by extrusion, as one integral piece. The insert 300 typically comprises uPVC, typically of calcium zinc type. However, it will be appreciated that a different plastics material, aluminium, other metals, alloys or any other suitable materials may equally be employed.

Referring now to Fig 4, a flexible sheet comprising a sign 112 is shown interposed between the upper rail 10 and the insert 300. Only an upper

peripheral region of the sign 112 is shown in Fig 4. The sign 112 is planar and rectangular and has width and height dimensions. The sign 112 consists of polyethylene, which is 100% recyclable, although other suitable materials can be used, such as paper or other plastic sheet material. The sign 112 may have printed markings provided on the periphery thereof, which can be used to align the upper peripheral region with longitudinally extending channel 258, thereby ensuring the installed sign 112 is horizontal.

Fig 4 shows the upper rail 10, the sign 112 and the insert 300 in a pre- insertion position, whilst Fig 5 shows these components in an engaged position. The sign 112 has a main portion 112m and an upper edge flap 112f. The main portion 112m is below the upper rail 10 and the upper edge flap 112f is above the upper rail 10.

During insertion of the insert member 300 into the channel 258, the ramp surface 352d engages the inclined surface 270a of the detent 270, the respective surfaces 352d, 270a facilitating a cam action. During insertion of the insert member 300 from the position shown in Fig 4 towards the position shown in Fig 5, the side wall 352b of the insert member 300 resiliently pivots towards its opposing side wall 352c. Once the barb 352e passes beyond the detent 270, the side wall 352b snaps back to its original position thereby positioning the barb 352e within the channel 258 behind the detent 270, the detent 270 being received in the recessed portion 370. The insert member 300 is thereby securely engaged within the channel 258.

Fig 6 shows an insert 300 and the lower rail 12 in situ on a lower end of the billboard 18. The lower rail 12 is attached directly to the billboard 18,

e.g. by bolts, screws, adhesive, nails or any other suitable fastening means.

The lower rail 12 may be of uPVC, a different plastics material, aluminium, alloy, or any other suitable material, and is preferably formed by extrusion. In this embodiment, the lower rail 12 is formed from uPVC, of the calcium zinc type.

The lower rail 12 is the same as the top rail 10, and like parts have like reference numbers, which commence with "400". The insert 300 is the same as the insert 300 described with reference to Figs 3 to 5. The lower rail 12 and the insert 300 are reversed in orientation, as compared to the top rail 10 and insert 300 shown in Figs 3 to 5. That is, the inwardly projecting detent 470 and the outwardly extending barb 352e are on the lowermost sides of the lower rail 12 and the insert 300 respectively.

Therefore, with respect to the frame formed by the four rails 10, 12, 14, 16, the detent 470 is on the outermost side wall.

The flexible sheet (e.g. an advertising sign) is not shown in Fig 6, but the lower end of this would be interposed between the insert 300 and the lower rail 12, and the sheet would extend upwards from the lower rail 12 to cover the surface of the billboard 18.

Fig 7 shows a modification of the Fig 6 embodiment, in which a lower flange 454 of the lower rail 12 terminates in an elongate protrusion 456 of c-shaped cross-section. Engaged with (and rotatably mounted on) the elongate protrusion 456 is a correspondingly shaped end 46Oe of a hinged cover 460. The hinged cover 460 is elongate, with a substantially L- shaped cross-section.

In Fig 7, the hinged cover 460 is in a closed position, in which it (together with part of the lower rail 12) substantially surrounds the channel 458. Specifically, a longitudinal rib 462 extends perpendicularly from the inner side of the hinged cover 460, and substantially meets the upper end of the lower rail 12. Thus, in the closed position, the channel 458 and insert 300 are not accessible (e.g. to vandals).

A lock (not shown) is provided such that the hinged cover 460 can be locked in the closed position. To open the hinged cover 460, it is unlocked, and the hinged cover 460 is rotated through about 90 degrees relative to the elongate protrusion 456, to provide access to the channel 458.

Although only illustrated in respect of the lower rail 12, a similar hinged cover 460 could also be provided for one or more of the upper rail 10, the left side rail 14 and the right side rail 16.

The left and right side rails 14, 16 shown in Fig 1 and 2 are identical to the upper and lower rails 10, 12 and are attached to the billboard 18 in the same way. The left and right side rails 14, 16 are also orientated such that, with respect to the frame formed by the four rails 10, 12, 14, 16, their respective detents 270 are on the outermost side walls of their respective channels.

An advertising sign is installed on the billboard 18 of Fig 1 as follows.

An operative arrives on site with the advertising sign 112 either rolled or folded horizontally with the top of the advertising sign 112 exposed on its outside edge. Other than optional printed indicia on the advertising sign 112 to assist in the placement of insert members 300 (as described

below), the sign 112 requires no modification or "finishing" prior to its installation. If the apparatus is provided with one or more hinged covers 460, the operative folds this/these down after unlocking any necessary retaining means.

The operative un-rolls or unfolds enough of the advertising sign 112 such that a central portion of its upper peripheral edge extends beyond the longitudinally extending channel 258 of the upper rail 10. If present, the printed markings provided on the periphery of the sign 112 are used to properly align the upper peripheral region with longitudinally extending channel 258 thereby ensuring the installed sign 112 is horizontal. It will be appreciated that the word periphery is used to denote the region of the advertising sign 112 at or near its respective edges.

The operative then inserts a relatively short longitudinally extending insert member 300 into a central portion of the channel 258 to thereby frictionally engage the sign 112 between the upper rail 10 and the insert 300 respectively. Again, if present, printed markings on the periphery of the sign 112 are used to ensure that the first short insert member 300 is positioned centrally. The operative then progressively inserts further insert members 300 on alternate sides of the central insert member 300 using the printed markings (if present) as a guide until the entire upper periphery of the sign 112 is engaged within the channel 258. The longer the insert member 300, the more difficult it is to properly tension and align the sign 112 and so insert members 300 of appropriate lengths are selected to overcome this difficulty.

An alternative method may involve firstly positioning three shorter insert members 300 at a central position, and both distal ends of each channel 258, (using the printed markings as a guide, if present), and then filling in

the gaps between the central insert member 300 with further insert members 300, which may be longer than the first three insert members 300.

Conveniently, the snap-fit arrangement of each insert member 300 within the channel 258 avoids the need to thread the sign 112 into engagement with the upper rail 10 from one end thereof. Therefore, lateral clearance at the side of the billboard 18 is not required.

Insertion of the insert member 300 into the channel 258 pushes the sign 112 into the channel 258. Specifically, the main portion of the sign 112m is pulled up into the channel 258, which tensions the sign 112.

It will be appreciated from Fig 5 that the arrangement of the insert member 300 within the channel 258 acts to resist any downward forces applied to the sign 112. This is important to ensure that an operative may apply a downward tensioning force to the advertising sign 112 during installation without the sign 112 detaching from the upper rail 10.

Downward forces applied to the sign 112 (e.g. to tension the sign 112) cause the insert member 300 to tend to rotate counter-clockwise about a pivot point 352f on the barb 352e. As the counter-clockwise rotation commences:

(i) the vertical face of the barb 352e pivots away from the inner vertical face of the detent 270;

(ii) the base of the recessed portion 370 pivots toward the inclined surface 270a of the detent 270; and

(iii) the side flange 360a pivots toward the exterior surface of the detent 270.

The absolute limit of the counter-clockwise rotation is dictated by the angle of the inclined surface 270a and/or the length of the side flange 360a and its clearance from the exterior surface of the detent 270. As soon as any counter-rotation of the insert member 300 occurs, a pinching action is created at the pivot point 352f such that the insert member 300 tightens its engagement with the interposed sign 112. The engagement force between the side walls 252c, 352c, and between the side flange 360a and the exterior surface of the detent 270 may also increase.

Hence, tensioning the sign 112 by pulling down on the body of the sign 112 after attachment to the upper rail 10 does not cause the insert member 300 to fall out, but instead actually causes the insert member 300 to engage the sign 112 more strongly in the channel 258.

Conversely, a sufficient upward force applied to the sign 112 causes the kink in the sign 112 caused by the presence of the barb 352e and the detent 270 to attempt to straighten out along the upper side wall 352b of the insert member 300. The resultant downward force applied to the barb 352e causes the side wall 352b to pivot clockwise towards the opposing side wall 352c until the upper end of the barb 352e disengages from behind the detent 270, thereby releasing the insert member 300 and the sign 112 from the channel 252.

The operative may then repeat the aforementioned steps by engaging the lower edge of the sign 112 between the lower rail 12 and by inserting additional insert members 300 into the channel 458.

Starting at a central portion of the sign 112, the operative manually tensions the sign 112 by exerting a downward force until the printed markings (if present) on its peripheral region align with the lower rail 12. The operative then inserts a relatively short longitudinally extending insert member 300 into a central portion of the lower channel 458 to thereby frictionally engage the sign 112 between the lower rail 12 and the insert 300 respectively. The operative then progressively inserts further insert members 300 on alternate sides of the central insert member 300 in equal stages using the printed markings (if present) as a guide until the entire lower periphery of the sign 112 is engaged within the lower rail 12. As each insert member 300 is inserted, the operative manually tensions the sign 112 to ensure the printed markings (if present) are properly aligned such that the sign 112 is horizontal.

The act of inserting the insert members 300 into the channel 458 tensions the sign 112. Specifically, the lower peripheral region of the sign 112 experiences an upwards tensioning force due to the sign 112 already being engaged with the upper rail 10 and due to the insert 300 pressing the sign 112 into the channel 458. This causes the main portion 112m of the sign 112 to be pulled down into the channel 458, tensioning the sign 112.

Since the orientation of the lower rail 12 and its insert member 300 are reversed as compared to the upper rail 10 and its respective insert member 300, the action of forces applied to the sign 112 will also be reversed. Therefore, in Fig 6, the arrangement of the insert member 300 within the lower rail 12 acts to resist any upward forces applied to the sign 112. This ensures that the advertising sign 112 will not detach from the lower rail 12 during installation, despite the sign 112 being under tension. However, applying a sufficient downwards force to a lower edge flap of the

sign 112 causes the kink in the sign 112 caused by the presence of the barb 352e and the detent 470 to attempt to straighten out, thereby releasing the insert member 300 and the sign 112 from the lower rail 12.

The operative may then repeat the aforementioned steps to engage the left and right edges of the sign 112 with the left and right side rails 14, 16 respectively, using further insert members 300, so that all four edges of the sign 112 are secured to the billboard 18, with the sign 112 being correctly tensioned.

Since the orientation of the left side rail 14 on the billboard 18 is such that the detent 270 is on the outermost side wall of its channel with respect to the frame, the arrangement of the insert member 300 within the left side rail 14 acts to resist any forces to the right applied to the sign 112. This ensures that the advertising sign 112 will not detach from the left side rail 14 during installation, even if the sign 112 is under tension. Specifically, the left edge of the sign 112 typically experiences a tensioning force to the right. The tensioning force to the right may be due to (a) the right side rail being already engaged with the sign 112 prior to the left side, (b) the upper and lower rails 10, 12, if already engaged will provide lateral tensioning and/or (c) an additional operative tensioning the sign 112. In all cases, inserting an insert member 300 into the channel 258 of the left side rail 14 pushes the main portion 112m of the sign 112 further into the channel 258, tensioning the sign 112. The tensioning causes the insert member 300 to grip the sign 112 more strongly in the channel 258.

However, applying a sufficient force in the left direction to the left hand flap of the sign 112 causes the kink in the sign 112 caused by the presence of the barb 352e and the detent 270 to attempt to straighten out, thereby releasing the insert member 300 and the sign 112 from the left side rail 14.

Since the orientation of the right side rail 16 on the billboard 18 is such that the detent 270 is on the outermost side wall with respect to the frame, the arrangement of the insert member 300 within the right side rail 16 acts to resist any forces to the left applied to the sign 112. This ensures that the advertising sign 112 will not detach from the right side rail 16 during installation, despite the sign 112 being under tension (specifically, the right edge of the sign 112 typically experiences a tensioning force to the left). However, applying a sufficient force to the right to the right hand flap of the sign 112 causes the kink in the sign 112 caused by the presence of the barb 352e and the detent 270 to attempt to straighten out, thereby releasing the insert member 300 and the sign 112 from the right side rail 16.

If present, the cover plate(s) 460 can then be brought into their closed positions (see Fig 7) and optionally locked, to conceal the rails 10, 12, 14, 16 from view.

If and when the sign 112 needs to be taken down and replaced with an alternative sign (e.g. with a different advertisement thereon), the above steps can be reversed.

The apparatus described above allows the posting of advertising signs which require no adaptation or "finishing" of their peripheral regions prior to installation. That is, the sign 112 does not include any clips, edge strips or other "finishing means". Hence the sign 112 is inexpensive and simple to produce. Accordingly, media owners can employ regular printers to print their signs thus avoiding costs associated with bespoke printing and finishing of a sign. The sign can therefore be installed and removed very quickly in a controlled manner regardless of weather conditions.

When removing and recycling/disposing of a sign, there is no need to first remove any added "finishing means", e.g. clips, edge strips. Hence, the sign 112 is very easy to dismount and replace, and this can also be done by a single person.

The sign 112 can consist entirely of polyethylene, so that it can be 100% recycled, which is beneficial for the environment.

Modifications and improvements may be incorporated without departing from the scope of the invention. For example, although the term "advertising sign" is used, the invention encompasses any sign, or indeed any flexible sheet. The sign may carry advertising material, but is not limited to an advertising use, and may carry information or decorative subject matter.

Although the channels and insert members are preferably formed by extrusion, they may equally be formed by injection moulding.

Although the insert member 300 shown in Figs 3-7 is shown as a separate component which is independent of the rails 10, 12, 14, 16, one or more of the respective insert members 300 may be permanently linked to their respective rails 10, 12, 14, 16 by means of a cord, and end hinge, hinge arrangement, or any other suitable means, optionally running longitudinally along the length of the rail 10, 12, 14, 16. This ensures that the insert member 300 is not misplaced and is always conveniently located ready for insertion within the channel of its respective rail 10, 12, 14, 16. In this way, an operative need only pivot the or each insert member 300 into a snap-fit engagement with the rail 10, 12, 14, 16. By providing a plurality of

insert members 300 along the length of the channel, the operative can progressively tension and attach a sign 112 as described above.

In an alternative embodiment the sign 112 (or other flexible sheet) comprises polyethylene but does not consist solely of polyethylene. In other embodiments, the sign 112 can be paper, toughened paper, laminated paper, fabric, a woven fabric mesh, or made from any other suitable material. In some embodiments, part of the sign 112 could be rigid whereas other parts could be flexible.

The components which are formed of uPVC could alternatively be formed of PVC or any other suitable plastic (or other) material.

The four rails 10, 12, 14, 16 may be engaged with the flexible sheet in any order.

Although in the illustrated embodiment, the channel and insert system is used on all four edges of the advertising sign 112, this is not necessarily the case. Optionally, only one edge of the flexible sheet may be secured in this way. Alternatively, only top and bottom edges may be secured in this way. The tensioning provided by just the upper and lower channels can be efficient enough so that it is not necessary to also tension and secure the left and right edges in the same way. The other edges of the flexible sheet may be secured in any suitable way, e.g. by clips.

In an alternative embodiment, it is not necessary for the rails 10, 12, 14, 16 to be permanently secured on the billboard 18 as shown. For example, the upper rail 10 could be attached to a pulley system for raising and lowering. In this way, the upper rail 10 can be lowered to ground level for attachment and removal of the sign 112. Such embodiments can avoid

operatives having to climb ladders, risking an accident, when installing and removing a sign 112 on a large billboard 18.

There is no need for the frame to be rectangular. Optionally, the frame could be any required shape, for example square, pentagonal, hexagonal, octagonal, T-shaped, etc. The rails 10, 12, 14, 16 can be formed in any required length, for any required shape.