The prior art embraces the use of a discrete type of reflector which is rigid in embodiment, or at least cannot be adapted to a curved surface, and designed to project sideways from an obstacle, or in any event to occupy a plane lying substan ially normal to the incident beam of light; reflectors of the type in question are fashioned from glass or plastic, and must be secured to the structure of the obstacle, sign or whatever object by means of screws, nails or bolts. Such reflectors have a low coefficient of refraction however, and certainly are not so effective that the outline or position of the structure to which they are attached can be made recognizable from a distance sufficient to afford an immediate warning and thus enable drivers to avoid the obstacle, especially at night time.

Given their especially small dimensions, moreover, neither are the reflectors in question sufficiently effective in providing a daytime warning, with the result that drivers may be uncertain as to what lies ahead, especially at dawn and dusk.

The prior art thus stands in need of improvement with regard to the possibility of overcoming the drawbacks outlined above• It will be discernible from the foregoing that the need exists for a reflector with a high refractive index, such as will give good night time visibility without projecting excessively from an obstacle, and thus avoid undesirable encroachment onto the carriageway; more exactly, the need exists for a refracting medium which can be associated with a fluorescent ground providing daytime visibility, and which can be produced at a sensible cost, made available in sizes larger than currently afforded in reflectors of the conventional type mentioned above, perhaps in continuous

strip format, and secured to any given surface, flat or otherwise, utilizing commonplace expedients such as nails in particular and/or adhesives where feasible.

The stated requirement is met, according to the invention, with a flexible refracting medium bonded or otherwise fixed to a metal backing layer and possessing a high coefficient of refrac ion; such a medium might comprise forma ions of microspherical metallic glass elements, for example, inscribed in hexagonal pockets of a heat-sealable resin matrix and overlaid with a transparent coating that will be plain, in the event that the refracted light is white, or tinted in the event that the refracted light is yellow, red or another colour, and could be associated with a film of fluorescent material in red, yellow or some other suitable colour to enhance the vision of obstacles in daylight hours. Seen in longitudinal section, the metallic backing layer exhibits a mixed linear profile composed of a rectilinear portion merging in succession with a portion in relief that appears as a half-undul tion or ridge exhibiting a pair of rectilinear flanks, converging vertically at an angle advan ageousl between 15X and 40x, of which the top ends are interconnected by an arc to a circle and the bottom ends joined likewise through interconnecting arcs to the rect linear por ions on either side; the rec ilinear portion thus allows better exploitation of the refractive surface in relief by.an incident beam of light, resulting in improved percep ibility of the obstacle per unit of distance. In a first embodiment of the invention the metallic backing layer supports a refractive film overlaid with a transparent coating that is either plain, or or tinted with uniform colouring across ^" the entire surface of the strip. In a second embodiment, the metallic backing layer supports two longitudinal parallel bands, the one refractive film with a plain or inted transparent coating, the other a film of coloured fluorescent material.

In a third embodiment, the metallic backing layer supports three longitudinal parallel bands, of which the two outermost are refractive film with a plain or tinted

transparent coating and the middle band is a film of coloured fluorescent material.

In a fourth embodiment, the metallic backing layer supports two transverse bands, each equal in length to approximately half the overall length of the backing layer, consisting in refractive films with different colour surfaces. In a fifth embodi ent, the metallic backing layer supports a refractive film with a plain or tinted transparent coating, which is overlaid in turn with transverse bands of a refractive coating different in colour, distributed according to the pitch of the undulated profile of the backing layer, and of individual width equal to half the pitch.

Advantages attributable to the invention are: the replacement of conventional reflectors fitted to hurters, quoins, posts, guard-rails, barriers and road signs in general, with lengths of the strip disclosed; ease of application to structures with a profile other than flat; the ready availability of refractive claddings with or without fluorescent colours, of small or notably large dimensions and in continuous strip format, in whatever shape may be considered most suitable, and without the need for special moulding dies; a more readily visible road sign.

The invention will now be described in detail, by way of example, with the aid of the five sheets of drawings attached, in which:

-fig 1 is a longitudinal section through a strip according to the invention, relative to the first three embodiments mentioned; -fig 2 is a perspective of the first embodiment of the strip according to the invention, comprising a refractive film faced with a plain or uniformly tinted transparent coating, which is shown mounted to a support and, in the interests of simplicity, without ^' any depiction of the hexagonal refraction elements;

-fig 3 is a plan of the strip of fig 2, showing the refraction elements;

-fig 4 is a perspective of the second embodiment of a strip

according to the invention, of which the surface is divided into two longitudinal bands, the one refractive and the other reflective, which is shown mounted to a support and, in the interests of simplicity, without any depiction of the hexagonal refraction elements;

-fig 5 is a plan of the strip of fig 4, showing the refraction elements;

-fig 6 is a perspective of the third embodiment of a strip according to the invention, of which the surface is divided into three longitudinal bands, the middle band reflective and the two outermost refractive, which is shown mounted to a support and, in the interests of simplicity, without any depiction of the hexagonal refraction elements; -fig 7 is a plan of the strip of fig 6, showing the refraction elements;

-fig 8 is a longitudinal section through the fourth embodiment of a strip according to the invention, which has a refractive surface divided transversely into two parts of different colour; "fi 9 is a perspective of the strip of fig 8, shown mounted to a support and, in the interests of simplicity, without any depiction of the hexagonal refraction elements; -fig 10 is a plan of the strip of fig 8, showing the refraction elements; -fig 11 is a longitudinal section through the fifth embodiment of a strip according to the invention, which has a refractive surface divided up into alternating transverse bands of different colour; -fig 12 is a perspective of the strip of fig 11, shown mounted to a support and, in the interests of simplicity, without any depiction of the hexagonal refraction elements; -fig 13 is a plan of the strip of fig 11, showing the refraction elements. Referring to the drawings, 1 denotes a refractive film for road signs, comprising a plain or tinted transparent surface coating, and to advantage, with refraction elements 2 of hexagonal shape (shown in figs 3, 5, 7, 9 and 12) that are metallic grey in colour and inscribed in white hexagonal

borders; the film is secured, for example with a layer of adhesive 3, to a metallic backing strip 4 which when seen in longitudinal section exhibits a mixed profile consisting in flat portions alternated with portions in relief appearing as half-undula ions or ridges.

The backing strip 4 might be embodied, for example, in annealed aluminium, brass or tin plate.

5 denotes a further layer of adhesive by means of which the metallic backing strip is secured to an additional backing layer of silicon paper 6, if envisaged, and 7 denotes an interfacing support, likewise if envisaged, embodied in plastic or metal and secured to the refractive strip with adhesive or other suitable means, by means of which the strip is applied to the structure of the road sign or obstacle.

In figs 1, 8 and 11, the letter A denotes the pitch of the strip profile, for example 15 mm, which is composed of a rectilinear portion B approximately 8 mm in length and a portion C in relief exhibiting the shape of a half- undulation or ridge, measuring approximately 7 mm in length when viewed in plan; the letter D denotes the angle ^■ formed between the converging flanks of the ridge, which to advantage is between 15 and 40 ; R denotes the radius, 2.5 mm approx, of the arc interconnecting the two flanks and incorporating the crest of the ridge, whilst r denotes the radius, 1mm approx, at the connection between each flank of the ridge and the adjoining rectilinear portion; H denotes the height of the ridge at its crest, which is 4 mm approx. In figs 4, 5, 6 and 7 of the drawings, 8 denotes a fluorescent film that might be red, yellow or any given colour and is fixed to the metallic backing strip 4, for example by means of the adhesive 3 aforementioned. In the second embodiment of the invention (figs 4 and 5), the metallic backing strip 4 is faced with two longitudinal and parallel bands of material, the one consisting in refractive film 1, the other in fluorescent film 8, of which the respective widths equal approximately half the width of the strip overall. In the third embodiment (figs 6 and 7), the

metallic backing strip 4 is faced with three longitudinal and parallel bands, the middle of which in fluorescent film 8 and the two outermost in refractive film 1.

In figs 8, 9 and 10, which illustrate the fourth embodiment of the invention, 9 denotes a second refract ve film different in colour to the film denoted 1, applied to the metallic backing strip 4 in such a way that the finished strip is divided into two full-width bands of contrasting colour and substantially identical length. In figs 11, 12 and 13, which illustrate the fifth embodiment of the invention, 10 denotes one of a plurality of bands of transparent paint different in colour to the refractive film 1 and disposed parallel to the ridges of the backing strip 4; the bands 10 in quest on are silkscreened direct onto the film 1 and spaced according to the pitch A of the mixed linear profile (fig 11).

The undeveloped depth A/2 of the single band 10 is equal to half the pitch A of the strip profile, and its position compassed by the median transverse axis of a flat portion B and the crest of an adjacent ridge C

In practice, the materials, the design details, and the nature, shape and dimensions of the refraction elements may require adaptation to the different applications encountered, likewise the proportional ratios between the rectilinear and curved portions of the strip profile and their relative dimensional values; accordingly, a final embodiment may differ from those no ionally described and illustrated while remaining equivalent in terms of the art and by no means straying from the bounds of protection afforded by the appended claims.