To be more exact, the invention refers to a sofa-bed where the part which makes up the bed, that is to say, the horizontal support and the mattress associated therewith, can be folded back on itself and is normally housed in the lower part of the sofa.

Due to its structure and construction, the sofa-bed according to the invention can be made with extremely light materials, for example extruded aluminium profiles or even wood with the relative metal hinges, so as to have a very limited overall weight.

BACKGROUND OF THE INVENTION The state of the art includes a sofa-bed comprising a fixed structure, consisting of rigid, lateral supporting elements, to which the bed structure is hinged ; the bed structure consists of three main panels, substantially rigid, connected to each other to define, in the open position, the horizontal plane of the bed on which the mattress rests.

The three main panels are also suitable to be folded by 90° with respect to each other, to assume a second, closed position, in which the mattress is folded back on itself in its median zone.

In this closed position, the mattress is included and compressed between the two outer panels which are arranged substantially parallel to each other.

In this way, the mattress faces upwards only when the panels are in the open position, while it is packed between

the panels when they are in the closed position.

It is clear, therefore, that in the closed position, which corresponds to the position where the sofa-bed is functioning only as a sofa, the mattress does not perform any function as a seating or softening element, since there is a panel interposed between the mattress and the users of the sofa.

Moreover, in the closed position/sofa function, the mattress is in a compressed condition which, as time goes by, causes the mattress to be prematurely worn and to progressively lose its characteristics of elasticity and softness.

Furthermore, associated with the three main panels there is a mechanism consisting of a combination of springs and tie rods which makes the whole structure - and hence the sofa-bed in its entirety - very complex, complicated and costly.

Sofa-beds such as are known to the state of the art are generally not very stable in their extended condition, and entail problems and difficulties in the opening and closing operations.

The present Applicant has devised and embodied this invention to overcome these shortcomings and to obtain further advantages.

SUMMARY OF THE INVENTION The invention is set forth and characterised in the main claim, while the dependent claims describe other characteristics of the main embodiment.

The main purpose of the invention is to achieve a sofa-bed wherein the part which makes up the bed, that is to say, the support connected to the structure of the sofa and the relative mattress, can be folded back in a simple manner, without the need to include levers or other complex

auxiliary mechanisms.

A second purpose of the invention is to achieve a sofa-bed which has a structure, especially that of the bed part, which is very strong and suitable to support very high stresses.

Another purpose of the invention is to achieve a sofa-bed wherein the mattress of the bed, at least in part, always remains facing upwards, that is, towards the seat-part of the sofa, both when the bed is open and horizontal, and also when it is folded back and replaced inside the sofa, so that the mattress can constitute the element which the users sit upon.

Moreover, a further purpose is to keep the mattress, when it is folded up to function as the padding of the sofa, in a non-compressed condition, with limited stress.

The sofa-bed according to the invention comprises a fixed structure which constitutes the base resting on the floor and a folding structure constrained to the fixed structure by means of pin means.

The folding structure consists of at least two articulated elements associated with each other by means of hinge means and equipped with means to support the mattress.

In the preferential embodiment of the invention, the sofa- bed comprises three articulated elements associated with each other by means of respective hinge means, wherein at least one functions as a back-rest in the sofa configuration.

In the closed position of the sofa-bed, the articulated elements are folded back upon themselves, and housed inside the fixed structure, with at least a segment of the mattress arranged horizontal and facing upwards to constitute the padding of the seat-part of the sofa.

According to a variant, in the closed position at least a

second segment of the mattress is arranged vertical to constitute the padding of the back-rest of the sofa.

To take the sofa-bed to its open position, the folding structure is removed from the fixed structure, progressively extending the articulated elements with the relative mattress support means until the mattress assumes a horizontal arrangement.

In a preferential embodiment, the sofa-bed comprises guide means located on the fixed structure and mating sliding means associated with the folding structure which make the opening and closing operations of the sofa-bed extremely easy and convenient.

Similarly, the guide means can be arranged on the folding structure and co-operate with sliding means arranged on the fixed structure.

BRIEF DESCRIPTION OF THE DRAWINGS These and other characteristics of the invention will become clear from the following description of two preferential forms of embodiment, given as a non-restrictive example with reference to the attached drawings wherein : Fig. 1 is a schematic side view of a first form of embodiment of the sofa-bed according to the invention in the closed position ; Fig. 2 is a schematic side view of the sofa-bed shown in Fig. 1, in an intermediate position ; Fig. 3 is a schematic side view of the sofa-bed shown in Fig. 1, in the open position ; Fig. 4 is a section from A to A of Fig. 3 ; Fig. 5 is a schematic side view of another form of embodiment of the sofa-bed according to the invention in the closed position ; Fig. 6 is a schematic side view of the sofa-bed shown in Fig. 5, in a first intermediate position ;

Fig. 7 is a schematic side view of the sofa-bed shown in Fig. 5, in a second intermediate position ; Fig. 8 is a schematic side view of the sofa-bed shown in Fig. 5, in the open position.

DETAILED DESCRIPTION OF PREFERRED FORMS OF EMBODIMENT With reference to the attached Figures, a sofa-bed 10 according to the invention, shown in two preferential forms of embodiment respectively in Figs. 1-4 and 5-8, can assume a closed position in which it constitutes a sofa (Figs. 1 and 5) and an open position in which it constitutes a bed (Figs. 3 and 8), in this case a double bed.

In the case that the sofa-bed is long enough, for example at least two or three places, it can be used in the bed configuration both in a longitudinal and in a transverse direction.

The sofa-bed 10 comprises a fixed structure 11, resting on the floor 25, and a folding structure 12 suitable to be folded back to be contained inside the fixed structure 11 in the closed position of the sofa-bed 10 and to be removed and extended in its open position.

In the embodiment shown in Figs. 1-4, the fixed structure 11, shown with a line of dashes, comprises a back-rest 13 and two lateral sides 14 of the sofa and remains substantially unchanged in the two positions of the sofa-bed 10.

The folding structure 12, which is suitable to define the seat-part of the sofa in the closed position and the whole bed in the open position, comprises two articulated beam elements 16 each consisting of three distinct segments, 116, 216,316, which, in this case, are made from tubular metal profiles, for example extruded aluminium.

The articulated beam elements 16 can also be made of other material, such as for example wood, plastic or other

suitable material, provided it is of a substantially rigid type and can be associated with hinges or other type of articulated metal joint.

Each articulated beam element 16 comprises a first segment 116, hinged at one end in the inner part of one side 14 of the sofa-bed 10 to end pins 19 ; and, at the other end, to a relative second segment 216 which in turn is hinged to a mating third segment 316.

Support elements 26 are also assembled on the fixed structure 11 and are suitable to co-operate with the first segments 116 to support them in the horizontal position.

Thanks to this composition, the articulated beam elements 16 can assume a plurality of folded back positions wherein the segments 116,216, 316 are angled with respect to each other in a variable manner (Figs. 1 and 2) and an extended position wherein the same segments 116,216, 316 are aligned longitudinally and can be clamped in this position (Fig. 3).

Respective legs 20 are also associated with the third segments 316, by means of pins 22, and are connected to each other by means of a transverse rod 21 which has a stiffening function.

In the embodiment shown in Figs. 1-4, the legs 20 can be folded, so that they can be arranged, in the closed position shown in Fig. 1, inside the fixed structure 11 without causing interference or occupying space.

The folding legs 20 can assume a retracted position in which they are accommodated inside the third segment 316 and a position in which they are suitable to be clamped outside it.

With each segment 116,216, 316 one or more bracket elements 17 are associated, protruding towards the inside of the sofa-bed 10, and are aligned with each other in the extended position of the articulated beam elements 16.

Between the corresponding segments 116,216, 316 of the two articulated beam elements 16, attached to the bracket elements 17, there are supporting panels 18 suitable to support a mattress 15.

To be more exact, with each pair of corresponding segments 116, 216,316 a supporting panel 18 is associated which has base sizes corresponding respectively to the length of the relative segment, 116 or 216 or 316, and to the distance between the two articulated beam elements 16.

The thickness of the supporting panels 18 is less than that of the articulated beam elements 16, so that the mattress 15 resting thereon is at least partly contained laterally by the articulated beam elements 16.

The supporting panels 18 can be constrained to the articulated beam elements 16 by elastic shock-absorber means.

In a preferential form of embodiment, the supporting panels 18 are made of multi-layer wood and include longitudinal through grooves suitable to make the supporting panels 18 more flexible.

In the closed position of the sofa-bed 10, the folding structure 12 has the articulated beam elements 16 with the respective first segments 116 in a substantially horizontal position, resting on the supporting elements 26, and the second 216 and third 316 segments folded back respectively into a position underneath and behind the first segments 116 (Fig. 1).

In this position, the first segments 116, the relative supporting panel 18 and the portion of the mattress 15 supported thereby define the seat-part of the sofa.

The remaining part of the mattress 15, that is to say the part in correspondence with the second 216 and third 316 segments, is arranged resting on the bottom 23 and on the

rear 24 of the sofa.

To take the sofa-bed 10 to its open position, and hence into its bed configuration, it is sufficient to lift the folding structure 12, making it rotate in correspondence with the end pins 19 (Fig. 2).

The second 216 and third 316 segments are then made to rotate to take the articulated beam elements 16 to their extended position, while the folding legs 20 are also rotated and clamped in a position resting on the floor 25 (Fig. 3).

In this position the articulated beam elements 16 are thus supported by the sides 14 by means of the end pins 19 and the folding legs 20, while the supporting panels 18, aligned with each other, support the mattress 15 in a horizontal position.

To return to the closed position of the sofa-bed 10 according to the invention the steps are followed in reverse.

To make the operations to change the configuration of the sofa-bed 10 more convenient, the bottom 23 can be of the flexible type, so that it can also be temporarily deformed to allow the folding structure 12 to pass more easily.

Moreover, the third segments 316 can be kept constrained, by means of suitable spacer means, for example of the rod or belt type, in a pre-defined position with respect to the second segments 216 in their removal stage.

In the embodiment shown in Figs. 5-8, the fixed structure 11 of the sofa-bed 10 comprises two sides 14, a rear panel 27 which functions as a back-rest 13 and a bottom 23 which functions as a base.

Inside each of the two sides 14 there is a frame 30 on which a polygonal guide 29 is attached, with a closed, substantially trapezoid development.

To be more exact, the polygonal guide 29 comprises a closed end 29a, a first long segment 29b and a second, shorter ascending segment 29c, a third plane segment 29d and a fourth, descending segment 29e connected to the first segment 29b by means of an outlet aperture 29f made on the upper part of the latter.

Two vertical guides 28, closed in correspondence with their lower ends 28a, are attached to the lateral ends of the rear panel 27.

In a preferential form of embodiment, the pairs of guides 28 and 29 are made with C-shaped metal profiles, the open side of which reciprocally faces the other open side and also the inside of the sofa-bed 10.

The folding structure 12 also comprises in this case two articulated beam elements 16, each associated with a respective side 14.

Each articulated beam element 16 comprises three segments hinged together : a first segment 116, a second segment 216 and a third segment 316.

The first segment 116 has at a first end a sliding element, in this case a roller 31, free to slide inside the vertical guide 28.

At the other end, the first segment 116 has a pin or hinge 32 to which a plate 33 is associated solid with a first end of the second segment 216.

A sliding element, in this case a roller 34, is attached to the plate 33 and is free to slide inside the respective polygonal guide 29 ; also attached to the plate 33 there is an abutment element 37, suitable to co-operate with a fixed striker plate 38 associated with the third segment 29d of the polygonal guide 29.

The second segment 216 is thus hinged to the first segment 116 and constrained to the guide 29 in correspondence with

one of its first ends, while at the other end it is connected to the third segment 316 by means of a hinge 35.

A leg 36, in this case of the fixed type, is associated with the third segment 316 and is suitable to rest on the floor 25 in the open position of the sofa-bed 10 (Fig. 8).

Each pair of corresponding segments 116,216, 316 has means to support the mattress 15, which are not shown in the drawings, for example consisting of wooden staves, panels, metal round pieces or other suitable elements.

The mattress 15 is advantageously constrained to these supporting means or to the articulated beam elements 16, possibly free to slide partly in a longitudinal direction to facilitate the movements to remove and close the folding structure 12.

In the closed position of the sofa-bed 10 (Fig. 5), the first segments 116 are arranged substantially in an erect position, slightly inclined, resting on the rear panel 27 with the rollers 31 in co-operation with the upper end of the vertical guide 28 ; the part of the mattress 15 attached to the supporting means supported by the first segments 116 faces forwards and defines the padding of the back-rest of the sofa configuration.

The second segments 216 and the third segments 316, on the contrary, are folded back on each other between the sides 14, substantially superimposed, with the mattress 15 in an outer position which, with its part in correspondence with the second segments 216, defines the padding of the seat- part of the sofa.

The two segments of mattress 15, respectively associated with the second segments 216 and the third segments 316, are separated from the respective support means, in such a way as not to cause any compression and reciprocal crushing.

The segment of folding structure 12 in correspondence with

the third segments 316 rests on the bottom 23 of the sofa- bed 10 and has the legs 36 housed in appropriate seatings made between the rear panel 27 and the segment of the mattress 15 associated with the first segments 116 and defining the padding of the back-rest.

The rollers 34 on the plates 33 abut against the closed ends 29a of the polygonal guides 29.

This configuration, with the rollers 31 and 34 arranged in co-operation with the ends of the respective guides 28 and 29, gives great solidity and stability to the folding structure 12 in its closed position even when there are strong stresses.

To arrange the sofa-bed 10 in its open position, the folding structure 12 is raised making the second segments 216 rotate initially around the respective pins 32 towards the rear panel 27 to remove the third segments 316 and the legs 36 (Fig. 6).

With this movement the sliding elements 34 slide partly upwards along the first segment 29b of the respective guides 29, slightly lifting the whole folding structure 12, while the rollers 31 progressively descend until they abut on the lower ends 28a of the respective vertical guides 28.

Subsequently (Fig. 7), the second segments 216 and the third segments 316 are rotated with respect to each other around the hinges 35 and distanced from the rear panel 27 to progressively take the folding structure 12 to its extended position.

With this movement of rotation, after having followed the second ascending segment 29c of the respective guide 29, which further lifts the folding structure 12 with respect to the fixed structure 11, the rollers 34 move into correspondence with the substantially plane third segment 29d of the same guide 29.

The abutment elements 37 are positioned against the relative striker elements 38, defining the position of the rollers 34 in the extended condition of the folding structure 12.

The roller 31 is free to slide vertically along the relative guide 28 according to the position assumed by the first segment 116 during the progressive extension of the second 216 and third 316 segment.

The articulated beam elements 16 are finally aligned longitudinally, with the leg 36 resting on the floor 25, so that the mattress 15 and the relative supporting means are taken to the horizontal defining the open position of the sofa-bed 10 (Fig. 8).

To obtain this alignment the first segment is lowered to a substantially horizontal position, taking the roller 31 to abut again on the lower end 28a of the vertical guide 28.

In this extended position too, the positioning of the rollers 31 and 34, one abutting against the lower end of the guide 28 and the other in co-operation with the striker elements 38, gives considerable stability to the folding structure 12.

In this extended position, the hinge 35 performs a bearing function which supports the whole structure in the bed configuration, therefore eliminating the need for structural connection elements, such as levers, brackets or similar, between the fixed structure 11 and the movable structure 12 and thus liberating the whole underlying space outside the fixed structure 11.

Moreover, the presence of fixed legs 36 increases the stability and solidity of the whole structure of the sofa- bed 10 in the extended position of the folding structure 12.

To take the sofa-bed 10 back to the closed position, the cycle of movement is repeated in the opposite sequence from

Fig. 8 to Fig. 5.

The third segments 316 are folded back with respect to the second segments 216, rotating them around the respective hinges 35, partly rotating the first segments 116 thanks to the upward sliding of the roller 31 inside the vertical guide 28.

The third segments 316 are pushed back towards the rear panel 27 so that the roller 34 follows the descending fourth segment 29e of the polygonal guide 29.

At the end of the fourth segment 29e, the roller 34 returns to the first segment 29b through the outlet aperture 29f and then abuts against the closed end 29a of the polygonal guide 29.

From this it can be seen how during the whole cycle to remove and close the folding structure 12, the roller 34 completes the whole travel along the relative guide 29, returning every time to the start-of-cycle position.

According to a variant which is not shown here, in correspondence with the outlet aperture 29f, the polygonal guide 29 has a little panel or fin kept elastically in a closed position and suitable to open downwards.

As it passes through the outlet aperture 29f, the roller 34 opens the panel which elastically closes again immediately afterwards, thus preventing the re-ascent of the roller 34, which returns to the starting position located at the beginning of the first segment 29b.

From the partly folded position shown in Fig. 6, during the progressive insertion of the third segment 316 below the respective second segment 216, helped by the descending sliding of the rollers 34 along the guides 29, the legs 36 engage with the first segment of the folding structure 12, that is to say the part supporting the mattress 15 included between the first segments 116.

Continuing to fold the third segment 316, the legs 36 progressively push the first segment of the folding structure 12 to rotate until it is taken into correspondence with the substantially erect position shown in Fig. 5, wherein the first segment acts as a back-rest in the sofa configuration.

The folding structure 12 is then folded back between the sides 14 of the fixed structure 11, returning the sofa-bed 10 to the sofa configuration.

The movement of the folding structure 12 in this embodiment is always guided due to the presence of the rollers 31, the sliding elements 34 and the corresponding guides 28 and 29 which make the operations to open/close the sofa-bed 10 easier at every step.

In the folded back position shown in Fig. 5, the front curved part of the mattress 15 and the corresponding support elements pass over the front part of the fixed structure 11, so that it is not necessary to provide front boards or appropriate means to contain the structure 11.

By using extruded profiles to make the articulated beam elements 16, it is already possible during the production step to make holes or attachment elements to clamp the upholstery or coverings which cover the mattress 15 and make the sofa-bed 10 aesthetically pleasing, particularly in its bed configuration.

It is obvious that modifications and/or additions may be made to the sofa-bed 10 described heretofore, but these shall remain within the field and scope of the invention.

For example, the composition of the articulated beam elements 16 may include a different number of segments 116, 216,316, the legs 20 and 36 may also be of the telescopic type, the pins/hinges 32,35 may be replaced by articulated joints or similar, or otherwise.