This invention relates to picture frames for displaying photographs, drawings, graphic artworks in general, licenses, price lists, menus and alike, in which the graphic artwork document is completely sealed and held within the frame.

Picture frames are objects of every day use or sight. Their esthetic appearance and construction are areas of constant innovation and design. A typical example of picture frames for use on a horizontal surface is the classic photograph holder stand to be placed on a table, on a work-desk or on a shelf. A simplest example of picture frame to be hanged on a wall may be represented by a back panel and a front glass panel joined together by a number of elastic clips.

Commonly, these objects are relatively heavy, often frangible when falling on the floor, and made with materials that to a large extent may be qualified as not recyclable. Metallic assembly hardware and/or metal brackets or eyelets for hanging the picture frame to a nail or similar fastener on a wall are commonly employed. In other cases, stability in an upright position on a horizontal rest surface is provided by a relatively large thickness and weight of the picture frame.

Because of the materials that are used and/or for the relative laboriousness of fabrication, the cost of these objects in many of the innumerable forms in which ■ there realized, are not negligible and very seldom they may considered low.

. Fabrications costs, environmental impacts of the material used weight are important characteristics that for a large number of .applications should advantageously be reduced as far as possible.

A picture frame for use on a table or for hanging on a wall of outstandingly light weight, entirely made of recyclable material, generally of a sole material, substantially by a single operation, that does not require any assembly hardware or parts of different material has been found to respond to the above noted objectives. The new novel picture frame of this invention couples to appreciable characteristic of rigidity and stability of shape an unsuspected lightness. Generally its weight is orders of manitude smaller than that of similar picture frames made according to the known fabrication designs and techniques and may be a slow as few grams per square decimeter of overall projected surface of the picture frame, generally comprised between 5 grams and few tens of grams per dm2.

By virtue of such an outstanding lightweightness, even considering the weight of the graphic artwork to be inserted in the picture frame, whether a photograph, a drawing, a paper document or alike, the whole assembly of a so-framed picture may be stably sustained for an indefinite time on the surface of a vertical wall by using a piece or short segment of commercially available bi-adhesive tape.

In practice, a picture frame destined to stand on a horizontal surface or to be hanged on a wall is, according to the present invention, fabricated from relatively thin sheet of a thermoplastic material, typically produced in ribbon, and lacking, per se, self-supporting capability, by hot deep drawing the thermoplastic sheet in a drawin Όg die.

The picture frame of this invention is composed of two similar semi-shells of deep drawn sheet of thermoplastic material, at least one of which or front semi-shell is transparent and stackable onto the other or rear semi-shell.

The rear semi-shell may itself be transparent and made of the same material of the front semi-shell, or more preferably is made with a sheet of bulk colored thermoplastic material and/or serigraphed or decorated in any other manner.

The shape of each deep drawn semi-shell of thermoplastic sheet is such to define a central portion or panel portion having a substantially flat surface that may be planar or cylindrical, contoured by a perimetral portion in the form of a channel shaped perimetral portion, salient in respect to the front surface of the planar or cylindrical surface of the central portion or panel. During the deep-drawing operation of the semi-shells in a suitably defined drawing die using a co-operating counterpunch of the thin sheet of thermoplastic material, a plurality of details (e.g. spaced undercuts, projections or inflexions, buttons, cut out wings and alike) in the salient channel shaped perimetral portions of both semi-shells are formed, such to cooperate in establishing by the eventual locking together of couples of said features, a stable union of the two semi-shells upon stacking one on the other without substantially leaving any void space there between.

Of course, the photograph or graphic artwork or document is placed between the two semi-shells before stacking one on the other and joining them stably together by press locking the cooperating details formed in the channel-shaped perimetral frame portion, and remains completely sealed and protected from atmospheric agents.

In any case, the press lockable joining details to stably fix together the two semi- shells, are all easily disengageable, if necessary by forcing therebetween a flat object or blade in order to exert a light diverging action, to permit substitution of the photograph or other graphical artwork held in the picture frame. Similarly, a window or hole may be present through the central flat portion of the rear semi- shell to permit to exert a separating force by pocking a finger therethrough.

Both sheets of thermoplastic material used for forming the rear or back semi- shell and the transparent front semi-shell are of a recyclable plastic material and preferably of a material having a low environmental impact in case of dispersion in the environment or burning.

Polystyrenes (PS, OPS), polyesters (A-PET, PET-G, G-A-G- '•> PET), polypropylenes, polycarbonates, polyacrylics, multilayer laminated sHeets (PE- PET, PE-PS, PE-PP) and PVC are example of flexible thermoplastic materials that may be produced in thin ribbon form and that are satisfactorily used for making picture framed according to the present invention. The deep drawing process through which the two semi-shells are geometrically defined, coupled to the fact that the two semi- shells are stacked one on the other, in practice without leaving any internal void space apart from the volume occupied by the photograph or artwork that is eventually sandwiched between the surfaces of the two central relatively flat portions of the two stacked semi-shell confers to the complete assembly coexistent characteristics of rigidity and of lightweightness that are absolutely inimitable in picture frame of more traditional make

Preferably, the central panel or flat portion of the two semi-shells does not have a planar surface but rather a cylindrical surface such to confer to the picture frame a slightly convex aspect, because such a preferred shape further enhances rigidity of the picture frame

The generally flat central portion of the rear or back semi-shell may be subject to a localized deep drawing such to define a protrusion on the rear side of the picture frame that is geometrically shaped and dimensioned such to serve either as stand of the picture frame when placed on a horizontal surface or to provide for an abutment surface against a vertical wall, thus eliminating the need of any further fabrication step following the shaping and geometrically defining of the semi- shells in respective deep drawing dies

The invention is defined in the annexed claims

The different features, advantages and details of the invention will become even more evident through the following detailed description of several preferred embodiments, referring to the attached drawings, wherein:

Figure 1 is a three-dimensional exploded view of two stackable semi-shells forming a picture frame for wall hanging made according to the present invention;

Figure 2 shows the two semi-shells stacked and joined together to form the picture frame, Figure 3 is an enlarged detail view of cooperating press lockable details;

Figure 4 is a profile view of the picture frame of Figures 1 and 2 sustained on a wall by interposition of a piece of bi-adhesive tape;

Figure 5 is a photographic view of the picture frame of the preceding figures;

Figures 6, 7, 8 and 9 illustrate an alternative embodiment of a picture frame in a self-standing form for use on a table or other flat or horizontal surfaces.

The Figures from 1 to 5 illustrate a picture frame according to the present invention destined to be supported by a piece of bi-adhesive tape on a wall (in an easily removable manner without leaving marks or holes in the wall surface) while the Figures from 6 to 9 illustrate an alternative embodiment of the picture frame destined to be placed in a self-standing position on a horizontal surface.

In both embodiments, the material used for the rear semi-shell was a sheet of bulk colored polyethylene (A-PET) having a thickness of 0.4 mm and a density of 1.35 kg/dm3.

The transparent front semi-shell was also made of polyethylene (A-PET) but uncolored and transparent, having a thickness of 0.4 mm and a density of 1.35 kg/dm1

In case of the picture frame for wall hanging (Figures 1-5), the projected area of the picture frame had the shape of an upside down trapezium for a total 3.85 dm2. The central panel 3 and 4 of semi-shells 1 and 2, respectively, was not planar but slightly curved, as a matter of fact its surface was cylindrical, such to confer to the object and in particular to the graphic artwork displayed a slightly convex aspect and at the same time enhancing the rigidity of the picture frame assembly.

As may be observed in the exploded view of Figure 1 and in the profile view of Figure 4, a portion, that is the top portion of the central panel was deep drawn to form a protrusion 5 on the rear side of the picture frame, shaped in a way to define a planar abutment surface against a wall, onto which a piece or segment of commercially availably bi-adhesive tape of expanded polyurethane (not shown in the figure) is eventually applied.

Both semi-shells 1 and 2 are hot deep drawn in order to form a perimetral portion or channel-shaped frame portion, respectively 7 and 6, which is salient with respect to the front surface of the central portion or panel. The cross-section profile of the perimetral portions 6 and 7 is generally a broken line defining a channel-shaped cross section of an irregular triangular form, the longer side of which, 6a, 7a, joins with the cross section line of the central portion and the shorter side of which, 6b, 7b, has a bent edge, 6c, 7c, that projects in a direction orthogonal to the surface of the central portion.

• Preferably, as shown, the hot drawing profile of the channel shaped salient .••perimetral portion does not have constant dimensions but they gradually vary from minimum dimensions, that in the depicted example are along the bottom side of the picture frame, to maximum dimensions along the top side of the picture frame.

In any case, the average ratio of deep drawing, that may be defined in terms of depth (p) and length of the considered side of the picture frame, was in the depicted example, of about 0.35.

Tests conducted for establishing the practical limits of the deep drawing ratio of the thermoplastic sheets such to ensure a perfect stability of form and rigidity, indicate in 0.1 the minimum limit of the average ratio of deep drawing for the type of thermoplastic sheet used.

Of course, the upper limit of such a ratio is more tied to esthetic considerations such to confer to the picture frame pleasant geometrical proportions than to produce an augmented technical effect of conferring a sufficient rigidity.

Even the shape of the salient perimetral frame 6 and 7 that is defined by hot deep drawing the sheets of thermoplastic material may be different from the one shown in the example (which is substantially of triangular form). Indeed the channel- shaped frame portion may have a broken line profile or a rounded profile. In any case, even in function of the geometry of the profile of the salient perimetral frame portion, the average ratio of deep drawing must be sufficiently large as to ensure a substantial rigidity and stability of form of the picture frame.