GB2274013A - Sign panel framing. - Google Patents

Abstract

A fastener 95 fittable between adjacent sign frame members 92, 93 to secure the same together in an extruded sign frame comprises frame-engaging portions 109, 110 adapted to slidably engage with cooperating portions 107 of the adjacent frame members to secure them mutually together. At least one of the frame-engaging portions 109, 110 is provided with tooth means 112 projecting therefrom and arranged so as to offer relatively little resistance to engagement of the fastener with the respective frame member but to bite into a portion of the frame member to prevent or restrict subsequent disengagement of the fastener from the frame member. The fastener is suitable for use in a frame construction for use with top-hanging sign panels in which the panel is filled into the upper frame member 92 by inserting an upper edge of the panel, provided with a rib, from the front at an angle to the plane of the frame and then moving the panel into the suspended condition in which the rib rests on a flange 97 provided within the upper frame member. <IMAGE>

Description

SIGN PANEL FRAMING This invention relates to the framing of sign panels.

This application is divided from British Patent Application No. 2241601, to which reference is hereby directed under Rule 24(3) of the Patents Rules 1990 (as amended).

Extruded aluminium sign frames are known in which the frame members are secured together at each mitered corner by means of screws passing through holes drilled in one frame member and received in mutually inwardly-dirted longitudinal channels defined by formations provided on the other frame member. British Patent No. 2,113,885 (Fig. 1; reference numeral 16) describes an example of such a frame.

The use of screws in this way suffers from a number of disadvantages. In particular, it can be inconvenient to drill the necessary holes, and fitting the screws can be awkward and time-consuming, especially in a confined area British Patent No. 1,204,677 (Figs. 16A, 16B) describes a sign in which adjacent sign frame members are secured together without the need for screws by means of a rightangled plastics fastener (25) fitted between each frame member. The fastener is arranged to be force fitted into longitudinal tunnels in the frame members, by being provided with voids which confer resilience on the fastener and cause it to bear outwards against the tunnel walls after fitting.

The known plastics fasteners overcome some of the problems associated with screw securement, but nevertheless suffer from a number of disadvantages, which have prevented them from replacing screws in practice.

In particular, the fasteners are unsuitable for use in sign frames s he type described in British Patent No.

2,113,885 (i.e. having a pair of longitudinal channels spaced relatively widely apart and suitable also for receiving screws). The plastic construction and the voids weaken the structure of the fastener unacceptably and its resilience can deteriorate with time, leading to breakage or loosening of the fastener.

A resilient metal corner fastener for sign frames is described in British Patent Application No. 2180615 A.

The security of fixing by such known fasteners, however, is not as reliable as conventional screw fixing.

According to one aspect of the present invention, there is provided a fastener fittable between adjacent sign frame members to secure the same together in a sign frame, the fastener comprising frame-engaging portions adapted to slidably engage with cooperating portions of the adjacent frame members to secure them mutually together, wherein at least one of the frame-engaging portions is provided with tooth means projecting therefrom and arranged so as to cffer relatively little resistance to engagement of the fastener with the respective frame member but te bite into a portion of the frame member to prevent or restrict subsequent disengagement of the fastener from the frame member.

Where the frame member carries formations defining a pair of longitudinal mutually inwardly directed channels, the fastener is preferably of metal (e.g. steel) and the or each toothed engaging portion of the fastener preferably comprises a rectangular plate arranged to slide between both channels, each side of the plate being received in one of the channels. The plate sides preferably carry rows of teeth to resist disengagement of the fastener.

The configurations of the engaging portions may vary from one to another. In particular, in the case of a corner fastener to be positioned between a top (or bottom) frame member of a rectangular top-hanging sign frame in which a single-segment sign panel is to be mounted and the side frame member which is to be removed for mounting/ demounting of the panel, the fastener should have two plates arranged to engage one with the top (or bottom) frame member and the other with the side frame member, the first having no such teeth and adapted to be releasable from the top (or bottom) frame member for said mounting/demounting and the second having said teeth and being substantially non-releasable from the side frame member.

The angle between the frame-engaging portions of the fastener, and the material from which the fastener is constructed, are suitably chosen to provide a restoring force when the fastener is in place, urging the frame members towards one another. Typically, the angle will be 90" or somewhat less than 900 (e.g. between about 70" and 90 , suitably about 850).

The present invention enables sign frames to be assembled easily and cheaply, and is applicable to all types of sign, e.g. box signs or signs in which the frame is fixed directly to a planar support surface, including signs in which the sign panel is mounted to the frame by means of beads and sign in which the sign panel is suspended from within the upper frame member.

British Patent No. 1,386,409 describes a sign frame in which the frame members have longitudinal channels to receive the edges of the sign panel (e.g. panels made of acrylic material such as perspex (TM)), and the panel is suspended from within the upper frame member so that the panel edges lie invisible within the frame.

The panel is fitted in the frame from the front by inserting an upper edge of the panel provided with a front rib into the channel of the upper frame member at an angle to the plane of the frame and then moving the panel into the suspended condition in which the rib rests on a flange provided within the channel.

Such frames can be fixed directly to a planar support surface (see Fig. 1 of GB 1,386,409) or can be incorporated in an extrusion for a box sign (see Figs. 2 and 3 of GB 1,386,409).

Such known frames suffer from a number of disadvantages.

In particular, as shown in Figure 1 of the accompanying drawings (which shows a vertical cross-section through the upper part of a prior art sign frame mounted directly to a planar support surface), the manner by which the panel 1 to be viewed from the right (i.e. the front) is suspended can cause the weight of a heavy panel to pull the upper frame member 2 downwards at the front. This can cause the member to buckle, which damages the frame and in turn can push the upper edge of the panel backwards, causing bending of the panel.

The resultant downwards bending of the flange 3 can also cause the sign panel to slip backwards. Such slipping is compounded by the natural tendency of the prior art sign panel to balance on the rear edge of the flange at a slight angle to the vertical so that the centre of gravity 4 of the panel is directly beneath the point of support 5. Any erosion of the rib material which might tend to round off the lower front corner of the rib 6 will further reduce the security of seating of the panel.

Apart from the unsightly effects of the distortion of the frame and the panel and the cost and trouble of repair or replacement of the damaged parts, there can be danger to members of the public standing underneath the sign, should parts of the frame or the panel break or come away, and in addition there can be danger if the bent panel suddenly springs forwards during cleaning or maintenance of the sign.

The above effects are found to be exaggerated by strong winds, and there have been reports of panels dislodging from such frames during severe storms.

It is found that wind blowing across the front of a sign panel can cause a relatively high pressure body of air to build up behind the panel, tending to bow the panel forwards to assume an aerofoil shape. The wind then can generate an aerodynamic "lift" force on the panel, similar in principle to the lift produced by an aircraft wing, tending to pull the panel out of the frame.

These effects can be compounded by particular circumstances. For example, in the case of multi-segment sign panels the wind can blow behind one segment as a gap opens between adjacent segments. In the case of gusty winds, even quite light gusts, if they are at or around a critical frequency, can set up resonance effects in the panel which can lead to very large movements of the panel.

The prior art signs are found to be particularly susceptible to such damage. British Patent Application No. 2241601, referred to above, describes and claims certain novel sign constructions which aim to go at least some way towards overcoming the above disadvantages while retaining the advantages of suspended sign mounting. The fasteners of the present invention are suitable for use with such signs.

According to a further aspect of the present invention, therefore, the fastener may be used in a sign in which sign frame members have longitudinal channels therein to receive the edges of a sign panel, the panel is suspended from within the upper frame member so that the panel edges normally lie invisible within the frame, and the panel is fittable in the frame from the front by inserting an upper edge of the panel, provided at or near the panel edge with a rearwardly projecting rib, into the channel of the upper frame member at an angle to the plane of the frame and then moving the panel into the suspended condition in which the rib rests on a flange provided within the channel.

This assembly enables the weight of the panel to be borne by the part of the upper frame member behind the panel and typically below the point of support of the upper frame member. That part of the frame member is shorter and less susceptible to bending than the other parts, and can bear the weight of the panel in such a way that any tendency to bend at the point of support or fixing is substantially reduced or eliminated. Thus, the assembly reduces the adverse effects of a heavy panel, in contrast to the signs known hitherto.

A further disadvantage of the known frames is the undesirable tendency for the suspended panel to move forwards or backwards on its supporting flange.

According to a further aspect of the present invention, the fastener may be used in a sign in which sign frame members have longitudinal channels therein to receive the edges of a sign panel, the panel is suspended from within the upper frame member so that the panel edges normally lie invisible within the frame, and the panel is fittable in the frame from the front by inserting an upper edge of the panel, provided at or near the panel edge with a projecting rib, into the channel of the upper frame member at an angle to the plane of the frame and then moving the panel into the suspended condition in which the rib rests on a flange provided within the channel, wherein the flange carries an upwardly projecting portion and the rib is adapted to engage with the upwardly projecting portion in such a way that the fitted panel is resistant to movement in one or more horizontal direction.

This further aspect, which is applicable both to frontand rear-hung sign panels, is found to dramatically improve the security of seating of the suspended panel on the supporting flange.

The signs described and claimed in British Patent Application No. 2241601 have enhanced resistance to the damaging effects of wind, compared to conventional signs, as will now be discussed with reference to Figure 2 of the accompanying drawings, which illustrates in vertical section: (a) and (b) a conventional front-hung sign in which the panel to be viewed from the right (the front) is hung from a front panel rib resting on a flat flange, and (c) a rear-hung sign in which the panel, also to be viewed from the right, is hung from a rear panel rib resting on a flange, which rib is adapted to engage with an upwardly projecting portion of the flange for seating the rib on the flange.

Referring to Figures 2(a) and (b), in which like parts are designated as for Figure 1, wind blowing upwards across the panel 1 mostly flows around the upper frame member 2 as shown by the solid arrows repIesenting streamlines. Under normal wind conditions the tendency of the wind te lift the panel 1 is slight (shown by the dotted arrow in Figure 2(a) representing a small leakage flow), but a strong gust or other effect causing the panel 1 to lift off the flange 3 (Figure 2(b)) immediately opens up a path within the frame along which a strong airstream 7 can develop. The lifting effect on the panel can then be considerable, as the flow velocity around the top of the panel will itself tend to provide an upward suction as well as the direct upward force on the rib 6.

Given a sufficient lifting effect and the aerodynamic pressure and resonance effects on the front face of the prior art panel as described above, tending to pull the panel out of the frame, panels mounted in the conventional frames can dislodge from the frame in a sequence of steps which can be thought of as generally the reverse of the normal mounting sequence described in GB 1,386,409.

In contrast, a rear-hung sign as described in British Patent Application No. 2241601 has generally a reduced tendency to admit wind flow into the top frame member (because of the reduced tendency to distort in the manner shown in Figure 1 for conventional frames), but if a small gap 8 does open (as shown in Figure 2(c)) the leakage flow (as shown by the dotted arrows) is small and in fact forces the rearward rib 6a more firmly into seating engagement on the rear flange 3a preventing reversal of the mounting sequence. Indeed, any minimal upwards lift on the panel that may occur only serves to increase the downward thrust on the top of the rib 6a, due to additional suction created if any air flows around the base of the flange 3a.

The fasteners of the present invention are applicable to all the general typos of sign frames, and in particular (i) to sign frames which are fixed directly to a planar support surface and (ii) to box signs. As will be well understood by those skilled in the art, and as described in GB 1,386,409 in relation to the frames taught therein, the sign panels may be single-segment or multi-segment panels. However, the method of mounting/demounting single-segment sign panels requires that one side frame member is fitted after the panel is mounted or is removed before the panel is demounted, to enable the margins of the panel to rest within all the frame members. A multisegment sign, on the other hand, is mounted/demounted segment by segment and can be mounted to/demounted from a complete frame if desired.

The following numbered paragraphs 1 to 3 describe in more detail certain forms of improved top-hung signs in which there may be used the fasteners according to the present invention 1. We mention firstly a form of such signs in which the upper frame member has a front wall and a back wall spaced apart by an interposed web to define the longitudinal channel, first and second flange means being provided, one of which may if desired comprise the aforementioned flange for supporting the panel, the said first flange means extending forwardly from the back wall into the channel, and the second flange means extending rearwardly from the front wall into the channel so that the said first and second flange means define between them a channel mouth for admitting the upper edge of the panel on fitting of the panel into the frame, the front flange means and front wall being adapted to at least partially shield the channel mouth from front-on view.

This feature provides an advantage, when the sign frame is incorporated into an internally illuminated box sign, of reducing the extent of the dark rim around the visible edge of the sign panel caused by the shadow thrown on the panel from the rear by the lower edge of the ear wall and the flange extending forwardly therefrom.

2. We mention secondly another form of such signs in which the upper frame member has front wall and a back wall spaced apart by an interposed web to define the longitudinal channel, and an additional wall is provided, generally upstanding (preferably substantially vertically) within the channel and spaced in front of the back wall, the said additional wall suitably rising from the upper side of flange means extending forwardly from the back wall into the opening of the channel. This feature provides an advantage of permitting a pin to be mounted in holes drilled from the front through both the upstanding and rear walls. During insertion of a multisegment sign panel into a sign frame carrying in a side frame member a resilient sign cushioning device (e.g. of the type described in British Patent Application No.

2241601), the pin is inserted in the holes immediately after inserting the first segment and keeps that segment pressed over into the channel of the side frame member, against the cushioning device, to permit insertion of the other segment(s). The pin is subsequently removed and the complete panel is moved back sideways a little way so that its edges then lie invisible within the frame.

3. We mention thirdly a still further form of such signs in which the frame members are formed of wall members and front beads releasably secured thereto to provide a box sign in which the bead of the upper frame member includes a first portion which overlies the front upper edge of the panel and a second portion which extends rearwardly of the panel and is releasably secured to the upper wall member, the said first bead portion and a front portion of said upper wall member being adapted to provide respectively a front wall and a back wall and the said second bead portion being adapted to provide a spacing web between the said front and back walls to define the longitudinal channel, the flange for suspending the sign panel preferably extending forwardly from said back wall into the opening of the channel.This feature provides an advantage of a box sign in which the sign panel can be inserted or removed by a choice of mechods, and even if the fixings securing the beads in position are inaccessible or otherwise cannot be released or secured.

Signs incorporating the fastener according to the invention may embody any one or more of the abovementioned aspects and forms of the invention described in British Patent Application No. 2241601, as desired.

The frame members and component parts thereof in accordance with the foregoing, including wall members and beads, are suitably extruded, conveniently from aluminium, and then cut to size.

If desired, any flanges or similar parts of frames can be adapted as to their effective length by fitting on an elongate sleeve of generally U-section and optionally thickened at the base of the U-section, which has the effect of bringing forward the operative front edge of the flange. Such a sleeve may typically be of plastics.

It should be noted that where expressions of direction or location, e.g. "front", "back", "upper", "lower" etc are used in pairs herein, they are, unless the context otherwise requires, to be understood as relative expressions.

For ease of understanding of the present invention, embodiments will now be described by way of example and without limitations, with reference to Figures 3 to 13 of the accompanying drawings, wherein: Fig. 3 shows a cross-sectional view through a top part of a sign; Fig. 4 shows a cross-sectional view through a top part of another sign; Fig. 5 shows a crcss-sectional view through a top part of a box sign; Fig. 6 shows a partial perspective view from below of a top wall of the box sign of Fig. 5; Fig. 7 shows an enlarged cross-sectional vrew of part of the box sign of Fig. 5; Fig. 8 shows a simplified perspective view from the front of the sign of Fig. 5 to illustrate a method of inserting the first segment of a multi-segment sign panel; Fig. 9 shows a schematic vertical cross-section of the view of Fig. 8 for greater clarity;; Fig. 10 shows an exploded and partially cut-away front view of part of a sign frame; Fig. 11 shows a sectional view along the line A-A of Fig. 10 looking in the direction of the arrows, and showing the sign in place; Fig. 12 shows a side view of part of the assembly illustrated in Fig. 10, looking in the direction of arrow B; and Figure 13 shows a perspective view of a modified form of the corner fastener appearing in Figs. 10 and 12, Referring to Figures 3 and 4, in which generally like parts are designated alike, the top part of the frame for displaying a panel 11 to be viewed from the left (i.e.

the front) is formed of an extruded aluminium upper frame member 12 of constant cross-section, mitered at the corners in conventional manner (not shown). The frame member has a back wall 13 from which extends forwardly a bottom flange 14, and a top wall 15 from the front of which depends a front wall 16, turned back as a front flange at 17, flanges 14 and 17 defining the opening or mouth 18 of a longitudinal channel in the frame member 12. The members forming the remainder of the frame (not shown) are of like construction.

The frame is fixed to a support 10 by means of a conventional screw 19 passing through a hole in back wall 12.

The display panel 11 is provided with a rearwardly projecting rib 20 along its upper edge. The rib 20 may alternatively be located slightly below the upper edge of the panel 11. In any event, the panel should rise above the bottom of the rib by a distance greater than the vertical height of the channel opening 18 so that panel edge lies invisible within the frame. The upper edge of the panel is inserted into the opening 18 at a suitable angle (e.g. from about 400 to about 50 , suitably about 45 , to the vertical), as shown by the dotted lines in Fig 3. Once the rib 20 has cleared the bottom flange 14 the panel is allowed to come into the vertical suspended position with the rib 20 resting on the flange 14.

To enhance the security of retention of the panel in the frame, the bottom flange 14 is turned up (e.g. at an angle of from about 203 to about 702, suitably about 40 , to the horizontal) to form a lip 21 at its front edge and the underside of the rib 2G correspondingly cut away.

The bottom flange 14 may conveniently carry strengthening webs (not shown), at the point at which the lip 21 starts and the corner where the bottom flange meets the back wall 13.

An elongate sleeve (not shown), typically of plastics (e.g. UPVC) and of generally U-section, and optionally thickened at the base of the U-section, may be fitted onto lip 21 from the front, by sliding the sleeve over the lip so that the lip is received in the sleeve channel formed by the U-section. In this way the frame can securely accommodate thinner panels 11, since the sleeve will bring the effective front edge of the lip forward by a distance corresponding to the thickness of the wall of the sleeve at the base of the U-section.

The top wall 15 is high enough above the opening 18 to permit the panel to be lifted sufficiently to bring its lower edge over the corresponding front wall 16 of the bottom frame member (not shown) and then dropped into the corresponding opening 18 of the bottom frame member. In the case of the side frame members, the spacing between the top wall 15 and the opening 18 allows the panels fitted in the frame to be slid sideways to facilitate insertion and removal of panels.

The top wall 15 extends forwardly from the back wall 13 beyond the plane of the panel 11 and the front wall 16 depends from the front of the top wall and in Fig. 3 angles back towards the panel. The arrangement and front appearance of the front wall 16 may be varied as desired, depending on the intended appearance of the frame when viewed from the front. As previously mentioned, the lower end of the front wall is turned back at 17 to meet the panel 11 normal to the panel front surface. This arrangement provides a pleasing appearance to the front of the frame, hides the margins of the panel from view, prevents dirt etc from entering the hollow interior of the frame members and assists in maintaining the panel in position on the bottom flange 14.

The frame member additionally carries formations of generally C-shaped cross-section defining channels 23, 24, respectively at the corner between the front wall 16 and the top wall 15, and at the corner between the top wall 15 and the back wall 13. These formations can receive screws for joining adjacent frame members at the mitered corners in conventional manner, or other corner fixings as described in more detail below with reference to Figures 11 to 14.

Referring next to Figures 5 to 9 of the drawings, a box sign for displaying a sign panel 31 to be viewed from the left (the front) is formed of extruded aluminium wall members 32 and extruded aluminium beads 33, mitered at the corners in conventional manner (not shown). The members forming the remainder of the box sign (not shown) are of like construction.

Depending from the wall member are a pair of ribs 3d,35 of unequal length, defining between them a channel 36 In which an extruded aluminium cross-brace 37 is received for internally bracing the box sign, as shown in Fig. 6.

The cross-brace 37 extends between the top and bottom walls of the sign.

The extruded length from which the cross-brace 37 is cut is configured so as to provide also diagonal bracing elements 38 for further bracing the cross-brace 37 to the box walls (in the drawings only the top bracing element 38 is shown).

More particularly, the extruded length for forming parts 37 and 38 includes a central portion "B" of channel cross-section to serve as the operative part of cross brace 37 and end portions "C" and "D" (of lesser transverse width than portion "B") provided with flanges 39,40,41 the first two of which receive rivets and/or screws to serve as the operative parts of diagonal bracing element 38. Portion "C" is cranked at an angle oG of about 147 , which has been found to provide particularly efficient bracing with minimal force on the box elements. Flange 39 is received in the front one 42 of a pair of mutually inwardly directed channels 42,43 defined by formations extending from ribs 34,44 depending from the wall member 32. The upper edge of flange 41 abuts against the lower edge of rib 34.

At the mitered corners of the box sign, channels 42 and 43 receive one limb 45 of a corner-angle (e.g. a right angle) connecting piece 46 in the manner shown generally in Fig. 6. The other limb of the piece 46 would be received in the corresponding channels of the frame side member (not shown) and the fixing made secure by screwing or riveting from within the box in conventional manner.

Extending forwardly from rib 44 is a formation 47 of complex cross-sectfc, of which part 48 defines with rib 44 and front portion 49 of the wall member 32 a slot 50 for receiving the tcp limb 51 of the bead 33. A screw 52 secures the bead 33 to the wall member 32, the bead profile being thinned at this point to facilitate screwing. The front limb 51a of bead 33 depends in front of formation 47 and these parts constitute respectively a front wall and a back wall to define between them a longitudinal channel 53 having an opening or mouth 54 for receiving the top edge of the panel 31.

The lower portion 55 of formation 47 carries a forwardly extending flange 56, turned up to form a lip 57 at its front edge and provided on its upper surface with a relatively thin upstanding wall 58 spaced in front of the portion 55, the function of which will be described later with particular reference to Figs. 8 and 9. Ribs 59,60 (see Fig. 7) provided at the rear of formation 47 define a longitudinal slot for receiving connecting plates (not shown) to enable two such wall members to be secured end to end for forming a large box sign.

The front limb 51a of bead 33 carries a rearwardly extending flange 61 turned up to an angle , suitably about 20-30 , to form a lip 62 at its rear edge. Lips 57 and 62 define between them the margins of the channel mouth 54 for admitting the upper edge of the panel 31, the front limb 51a of bead 33, the flange 61 and lip 62 being arranged to shield the upper region of the channel mouth from front-on view.

In this way, the visible area of shadow "A" (shown by dots in Fig. 5) cast on the panel 31 from behind when the box sign is internally illuminated is minimised, and additionally the upwardly pointing configuration of lip 62 limits the passage of dirt and moisture into the channel 53 in the event that a gap opens up between the lip 62 and the panel 31.

The panel 31 is provided with a rearwardly projecting rib 64 along its upper edge. The panel rises above the bottom of the rib 64 by a distance greater than the vertical height of the channel opening 54 so that the panel edge lies invisible within the frame.

To insert the panel 31 while the bead 33 is in place, the upper edge of the panel is inserted into the opening 54 at a suitable angle, as shown by the dotted lines in Fig.

5. Once the rib has cleared lip 57 the panel is allowed to come into the vertical position with the rib 64 resting on the lip 57. To remove the panel while the bead 33 is in place, the procedure is reversed.

Alternatively, the bead 33 can be removed and panel 31 mounted and demounted in conventional manner. The arrangement illustrated enables a choice of mounting/demounting methods, to cater for local circumstances such as inaccessibility of the screw 52.

Bead 33 carries ribs 65,66 defining a pair of mutually inwardly directed channels 67,68 under the top limb 51.

These channels receive sign cushioning devices (not shown) in the manner described in more detail below, with reference to Figures 15 to 17. It may occasionally be desirable also for corner-fixing pieces (not shown) to be inserted into channels 67,68 at the mitered corners in the manner described in more detail below with reference to Figures 11 to 14.

With reference particularly to Figs. 8 and 9, the purpose of wall 58 will be described in more detail. Where it is desired to insert a multi-segment panel 31 into a sign frame carrying in a side frame member a resilient sign cushioning device (e.g. the leaf spring device described below with reference to Figs. 15 to 17), the first inserted segment must be pushed hard over into the channel of the side frame member (not shown), to the left as seen in Fig. 8, in order that the next segment may be inserted for hanging on the lip 57.To keep the first segment pressed over to the side, against the restoring force of the cushioniny device, small through-holes 69,70 are previously drilled at the correct point along wall 58 and lower portion 55 of formation 47 and a pin 71 inserted into the holes after the panel segment has been positioned, to keep the segment in position while the remaining segments are inserted. After the complete panel is inserted, the pin 71 is removed and the panel adjusted so that all its margins lie invisible within the sign frame.

Referring now to Figs. 10 to 13, the top of a frame for displaying a panel 91 is formed by extruded aluminium upper 92 and side 93 frame members of constant crosssection, mitered at the corner region 94 in conventional manner, retained together by a fastener 95 interposed between the frame members 92,93 in the corner region 94.

Referring particularly to the top frame member 92, this has a back wall 96 from which extends forwardly a bottom flange 97, and a top wall 98 from the front of which depends a front wall 99, turned back as a front flange at 100, flanges 97 and 100 defining the opening or mouth 101 of a longitudinal channel in the frame member 92. Side frame member 93 and the members forming the remainder of the frame (not shown) are of like construction.

The frame is fixed to a support 90 by means of a conventional screw 102 passing through a hole in back wall 96.

The display panel 91 is provided with a rearwardly projecting rib 103 along its upper edge. The upper edge of the panel is inserted into the opening 101 at a suitable angle to the vertical, as shown by the dotted lines in Figure 12. Once the rib 103 has cleared the bottom flange 97 the panel is allowed to come into the vertical suspended position with the rib 103 resting on the flange 97.

To enhance the security of retention of the panel in the frame, the bottom flange 97 is turned up and the underside of the rib 103 correspondingly cut away The top wall 98 extends forwardly from the back wall 96 beyond the plane of the panel 91 and the front wall 99 depends from the front of the top wall. As previously mentioned, the lower end of the front wall is turned back at 100 to meet the panel 91 normal to the panel front surface. This arrangement provides a pleasing appearance to the front of the frame, hides the margins of the panel from view, prevents dirt etc from entering the holiow interior of the frame members and assists in maintaining the panel in position on the bottom flange 97.

The frame member additionally carries formations defining channels 106, 107 of generally C-shaped cross-section, respectively at the corner between the front wall 99 and the top wall 98, and the corner between the top wall 98 and the back wall 96.

The channels 106, 107 are directed mutually inwardly, and each cooperates with part of the fastener 95 in the corner region 94 to secure the upper and side frame members together.

The fastener 95 is formed of a single rectangular piece of zinc plated spring steel bent round in the centre to form a piece of generally L-shaped configuration having a central heel portion 108 and two portions 109, 110 extending therefrom at a relative angle of about 85".

The terminal portions of the fastener 95 have chamfered corners 111 to assist in guiding the sides of each portion 109, 110 into sliding engagement with the Cchannels 106, 107 of respectively the upper 92 and side 93 frame members.

The fastener 95 shown in Figs. 10 and 11 is arranged to be push-fittable into said engagement with the frame members, but is provided at each side with rearwardly directed tangs 112 extending alternately to different sides of the relevant C-channel, the tangs 112 offering relatively little resistance to assembly of the fastener and the frame members and relatively great resistance to corresponding disassembly.

Fig. 13 illustrates a modified form of the fastener 95 with like parts designated as for Figs. 10 to 12. One portion 110, for inserting into a side frame member, carries tangs 112 as before, but the other portion 109, for inserting into a top or bottom frame member, takes the form of a plate without tangs but folded so as to have transverse ridges 113 and valleys 114 to rest in the C-channels 106,107. A split screw hole 115 is provided on the centre line of the portion 109 to take a self tapping screw after insertion of the fastener into the frame member, the screw thereby releasably locking the fastener in the frame member. The arrangement enables a side frame member to carry at each end a corner fastener so as to present tangless portions 109 for insertion into the top and bottom frame members.The side frame member is thus made releasable from the remainder of the frame, which as previously explained is necessary for framing a top-hanging single-segment sign panel in systems where the panel is inserted into the frame from the front at an angle to the plane of the frame and then brought into the suspended condition.

The following experiment has been performed to investigate the aerodynamic performance of the signs of the type shown generally in Figure 4 (referred to below as "Sign I"), in comparison with the conventional signs of the type shown generally in Figure 2(a) (referred to below as "Sign II").

Introduction/Method An experiment was perforiaed at in order to determine whether there was any aerodynamic advantage between Signs I and II. Two nominally identical perspex panels were attached to a central section of the appropriate mounting frame.

This experiment assumed that the frictional retarding force acting between the perspex panel sliding over the extruded aluminium frame is the same for each test configuration. Since these forces were identical, any panel movement induced by blowing high pressure air around the frame can be seen as a measure of the aerodynamic susceptibility of the frame design.

The panel and frame arrangements were placed, windward face up on a flat surface so that the panel could slide about horizontally over the lips of the frame. By raising the height of the frame part corresponding to the bottom of the sign frame, an angle of inclination was found which had the same retarding friction force for both signs.

A small 40 psi (2.8 kg/cm2) jet of compressed air was blown around the frame part corresponding to the top of the sign frame. Observations were taken of panel movements induced in this manner, which enabled a comparison of their aerodynamic performance to be made.

Observations/Discussion Separate tests showed that the friction coefficients and the frictional forces were identical within the accuracy of the experimental method. As a result, the aerodynamic performance of the frames can be compared with confidence.

The two signs were initially set so that the mounting strip was placed in contact with the lip of the frame.

No movement of either panel was observed, even after placing the air jet as close as possible to the mounting strip, and angled from every frontal direction. However, when both panels were set to simulate about 5mm of vertical movement away from the lip of the frame, the Sign II panel could be moved rapidly with the air jet positioned about 60mm from the frame. The Sign I panel could only be moved by moving the jet closer to the frame, and at 30mm a slow movement of the panel was observed. The rate of panel movement remained about the same, even when the air jet was positioned as close as possible to the Sign I frame.

Conclusion Sign I is less susceptible to aerodynamic lifting forces than Sign II.

Claims (20)

1. A fastener fittable between adjacent sign frame members to secure the same together in a sign frame, the fastener comprising frame-engaging portions adapted to slidably engage with cooperating portions of the adjacent frame members to secure them mutually together, wherein at least one of the frame-engaging portions is provided with tooth means projecting therefrom and arranged so as to offer relatively little resistance to engagement of the fastener with the respective frame member but to bite into a portion of the frame member to prevent or restrict subsequent disengagement of the fastener from the frame member.

2. A fastener according to claim 1 for use with a frame member which carries formations defining a pair of longitudinal mutually inwardly directed channels, the fastener being of metal and each engaging portion of the fastener comprising a substantially rectangular plate arranged to slide between both channels, each side of the plate being received in one of the channels and at least one side of the plate carrying the tooth means to resist disengagement of the fastener.

3. A fastener according to claim 1 or 2, when present in a sign in which sign frame members carry formations defining a pair of longitudinal mutually inwardly directed channels, the fastener being of metal and each engaging portion of the fastener comprising a substantially rectangular plate arranged to slide between both channels, each side of the plate being received in one of the channels and at least one side of the plate carrying the tooth means to resist disengagement of the fastener.

4. A fastener according to claim 1 or 2, when present in a sign in which sign frame members have longitudinal channels therein to receive the edges of a sign panel, the sign panel is suspended from within the upper frame member so that the panel edges normally lie invisible within the frame, and the panel is fittable in the frame from the front by inserting an upper edge of the panel, provided at or near the panel edge with a rearwardly projecting rib, into the channel of the upper frame member at an angle to the plane of the frame and then moving the panel into the suspended condition in which the rib rests on a flange provided within the channel.

5. A fastener according to claim 1 or 2, when present in a sign in which sign frame members have longitudinal channels therein to receive the edges of a sign panel, the panel is suspended from within the upper frame member so that the panel edges normally lie invisible within the frame, and the panel is fittable in the frame from the front by inserting an upper edge of the panel, provided at or near the panel edge with a projecting rib, into the channel of the upper frame member at an angle to the plane of the frame and then moving the panel into the suspended condition in which the rib rests on a flange provided within the channel, wherein the flange carries an upwardly projecting portion and the rib is adapted to engage with the upwardly projecting portion in such a way that the fitted panel is resistant to movement in one or more horizontal direction.

6. A fastener according to claim 1 or 2, when present in a sign in which sign frame members have longitudinal channels therein to receive the edges of a sign panel, the panel is suspended from within the upper frame member so that the panel edges normally lie invisible within the frame, and the panel is fittabie in the frame from the front by inserting an upper edge of the panel, provided at or near the panel edge with a projecting rib, into the channel of the upper frame member at an angle to the plane of the frame and then moving the panel into the suspended condition in which the rib rests on a flange provided within the channel, wherein the upper frame member has a front wall and a back wall spaced apart by an interposed web to define the longitudinal channel, first and second flange means being provided, the said first flange means extending forwardly from the back wall into the channel and the said second flange means extending rearwardly from the front wall into the channel so that the said first and second flange means define between them a channel mouth for admitting the upper edge of the panel on fitting of the panel into the frame, the said second flange means and front wall being adapted to at least partially shield the channel mouth from front-on view.

7. A fastener according to claim 1 or 2, when present in a sign in which sign frame members have longitudinal channels therein to receive the edges of a sign panel, the panel is suspended from within the upper frame member so that the panel edges normally lie invisible within the frame, and the panel is fittable in the frame from the front by inserting an upper edge of the panel, provided at or near the panel edge with a projecting rib, into the channel cf the upper frame member st an angle to the plane of the frame and then moving the panel into the suspended condition in which the rib rests on a flange provided within the channel, wherein the upper frame member has a front wall and a back wall spaced apart by an interposed web to define the longitudinal channel, and an additional wall is provided, generally upstanding within the channel and spaced in front of the back wall.

8. A fastener according to claim 1 or 2, when present in a sign in which sign frame members have longitudinal channels therein to receive the edges of a sign panel, the panel is suspended from within the upper frame so that the panel edges normally lie invisible within the frame, and the panel is fittable in the frame from the front by inserting an upper edge of the panel, provided at or near the panel edge with a projecting rib, into the channel of the upper frame member at an angle to the plane of the frame and then moving the panel into the suspended condition in which the rib rests on a flange provided within the channel, wherein the frame members are formed of wall members and front beads releasably secured thereto to provide a box sign in which the bead of the upper frame member includes a first portion which overlies the front upper edge of the panel and a second portion which extends rearwardly of the panel and is releasably secured to the upper wall member, the said first bead portion and a front portion of said upper wall member being adapted to provide respectively a front wall and a back wall and the said second bead portion being adapted to provide a spacing web between the said front and back walls to define the longitudinal channel.

9. A fastener and sign assembly according to any of claims 5 to 8, wherein the sign panel is provided with a rearwardly projecting rib and the flange on which the rib rests is provided within the channel so as to be to the rear of the fitted sign panel.

10. A fastener and sign assembly according to any preceding claim other than claim 1, 2 or 5, to the extent that such preceding claim is not dependent on claim 5, wherein the flange on which the rib rests is an upwardly projecting portion and the rib is adapted to engage with the upwardly projecting portion in such a way that the fitted panel is resistant to movement in one or more horizontal direction.

11. A fastener and sign assembly according to claim 5 or 10, wherein the upwardly projecting portion of the flange on which the rib rests in an upwardly sloping lip of the flange and the rib is correspondingly cut away along its underside.

12. A fastener and sign assembly according to any preceding claim other than claim 1, 2 or 6, to the extent that such preceding claim is not dependent on claim 6, wherein the upper frame member has a front wall and a back wall spaced apart by an interposed web to define the longitudinal channel, first and second flange means being provided, the said first flange means extending forwardly from the back wall into the channel and the said second flange means extending rearwardly from the front wall into the channel so that the said first and second flange means define between them a channel mouth for admitting the upper edge of the panel on fitting of the panel into the frame, the said second flange means and front wall being adapted to at least partially shield the channel mouth from front-on view.

13. A fastener and sign assembly according to claim 6 or 12, wherein the second flange means and front wall are adapted to shield only the upper region of the channel mouth from front-on view.

14. A fastener and sign assembly according to any preceding claim other than claim 1, 2 or 7, to the extent that such preceding claim is not dependent on claim 7, wherein the upper frame member his a front wall and a back wall spaced apart by an interposed web to define the longitudinal channel, and an additional wall is provided, generally upstanding within the channel and spaced in front of the back wall.

15. A fastener and sign assembly according to claim 7 or 14, wherein the said additional wall rises from the upper side of flange means extending forwardly from the back wall into the opening of the channel.

16. A fastener and sign assembly according to any preceding claim other than claim 1 or 2, when in the form of a box sign, wherein the box is internally braced by means of at least one cross-brace and diagonal bracing element each cut from extrusions of substantially identical cross-section.

17. A fastener and sign assembly according to any preceding claim other than claim 1 or 2, wherein the sign panel is a multi-segment panel fittable into the frame segment by segment.

18. A fastener and sign assembly according to any one of claims 3 to 16, wherein the sign panel is a singlesegment panel and a side frame member is capable of being detached to permit the panel to be fitted into the frame and subsequently replaced to enable the edges of the fitted panel to lie invisible within the frame.

19. Fasteners, substantially as herein described with reference to Figures 10, 12 and 13 of the accompanying drawings.

20. Fastener and sign assemblies, substantially as herein described with reference to Figures 3 to 13 of the accompanying drawings.