Background Art Chairs, particularly office chairs, in which it is possible to adjust the height of the seat and/or the inclination of the back are already known.

These chairs are substantially composed of a base for resting on the floor, generally provided with castors and from which a column rises upwardly and supports a rigid shell which forms the seat, which is padded in an upward region.

An L-shaped arm protrudes from the shell to the rear and ends with a rigid shell which forms the back, which is conveniently padded at the front.

The height adjustment of the seat and the tilting of the back occur respectively by virtue of the extension of the vertical column, normally including a gas-filled cylinder which can be operated by means of a lever, and by tilting the L-shaped support of the back by virtue of spring elements and knobs.

The adaptability of the chair to the posture of the user is therefore at present the result of adjustments which the user can perform by means of levers and/or knobs, while comfort is closely linked to the quality of the padding of the seat and/or back.

However, current chairs cannot vary their overall configuration continuously and automatically during use according to the various positions and postures assumed by the user in the possibly long periods for which he remains seated.

Disclosure of the Invention The aim of the present invention is to provide a seat with a structure which can change its shape and its configuration continuously according to the position and posture assumed by the user without requiring direct intervention of the user.

Within this aim, a consequent primary object of the invention is to improve seating comfort for the user.

Another important object of the invention is to provide a chair which can adapt without problems to users having different body weights.

Another object of the invention is to provide a chair which in any case integrates the height and back inclination adjustments provided in current chairs.

This aim and these and other objects which will become better apparent hereinafter are achieved by a chair characterized in that it comprises a seat supported by deformable elastomeric arms which connect it to a rigid support provided with means for resting on the floor.

Advantageously, the chair comprises a back being supported by deformable elastomeric arms for connection to a rigid support which is associated with said seat support.

Brief description of the drawings Further characteristics and advantages of the chair according to the present invention will become better apparent from the following detailed description of some embodiments thereof, illustrated only by way of non- limitative example in the accompanying drawings, wherein: Figure 1 is a perspective view of a chair with armrests according to the present invention; Figure 2 is a rear view of the back of the chair of Figure 1; Figure 3 is a partially sectional enlarged-scale perspective view of a detail, in a region for the coupling of the back to the corresponding support; Figure 4 is a side view of the chair of Figure 1, showing its configuration adjustment movements in dashed lines; Figure 5 is an enlarged-scale view of a detail of the front part of the seat; Figure 6 is a partially sectional exploded perspective view of the detail of Figure 3; Figure 7 is a sectional view of the elements of Figure 6 in the assembled

condition; Figure 8 is a perspective view of a detail of the chair; Figures 9 and 10 are respectively a rear view and a side view of a second embodiment of the chair with adjustable-height armrests.

Ways of carrying out the invention With reference to the figures, a chair according to the invention is generally designated by the reference numeral 10 and comprises a seat 11 being supported by four deformable elastomeric arms 12 which are arranged so as to outline a quadrilateral and connect the seat to a rigid support 13 (for example made of metal) provided with means for resting on the floor being constituted by a base 14 with castors and a corresponding column 15 of the telescopic type, which is per se known.

Advantageously, the back 16 is supported by four deformable elastomeric arms 17 which connect it to a rigid support 18 (for example made of metal) being associated with the rigid support 13 of the back 11 by means of a pair of rigid parallel shaped rods 19 which also are made for example of metal.

The elastomeric arms 12 and 17 are fixed at their ends, at the seat 11 or at the back 16, by means of snap-acting couplings, generally designated by the reference numeral 20, which comprise a dome-shaped end 21 of the arm 12 or 13 in which a central seat 22 having a noncircular cross-section is formed axially and peripheral seats 23 are provided which form undercuts 24 for engagement.

A complementarily shaped pin 25 can be inserted in the seat 22, protrudes from a plate 26 and is surrounded by hook-shaped protrusions 27 which can flex elastically and can be inserted with a snap action in the peripheral seats 23 by elastic deformation and subsequent coupling to the undercuts 24, as shown in Figure 7.

The elastomeric arms 12 and 17 taper from the region for coupling to the rigid supports 13 or 18 to the region for coupling to the seat 11 or to the

back 16.

This is done so that their response to the forces applied by the user, for example due to his weight, is gradual, in that the regions closest to the seat 11 or back 16 start to deform first, as shown in particular in Figure 5.

The figures further show that the arms 12 and 17 have a central configuration which is substantially parallel to the resting plane of the seat 11 or back 16, so that the deformation applied to them is predominantly flexural.

The seat 11 and the back 16 are preferably made of an elastomeric gel in which the plates 26 are embedded; the plates can also be made of the same material but with a higher density.

As an alternative, padded structures can also be provided.

The chair 10 is provided with armrests 28 which protrude from the rigid support 13.

It is also possible to provide, as in Figures 1 and 8, a front part 29 of the seat 11 which can slide longitudinally by being rigidly coupled to two parallel rods 30 being slidingly coupled to guides, not shown, which are integrated in the rigid support 13.

With reference now to Figures 9 and 10, the armrests, now designated by the reference numeral 31, can protrude from the rods 19 and be slidingly coupled thereto in order to allow to adjust their height.

Accordingly, sliding sleeves 32 are provided which surround the rods 19 and from which the armrests 31 protrude.

The intended position can be set by means of screws.

It is also possible to provide a lumbar cushion 33 which is rigidly coupled at the front of the support 18 of the back 16 and whose height can be adjusted by being slidingly coupled to the support.

As to operation, the chair 10 can be adjusted as regards the height of its seat and the inclination of its back in the conventional manner by adjusting the column 15 and tilting inclination of the rods 19.

This adjustment is"rigid", in that it can be performed only if the user acts on knobs or levers and maneuvers them.

In use, however, there is a continuous adjustment which adapts the configuration of the seat 11 and the back 16 to the various forces that act thereon, which can be both symmetrical and asymmetrical.

The arms 12 and 17 in fact flex according to the load applied thereto and therefore the corresponding part of the seat 11 or back 16 adapts accordingly.

The seat and back are made entirely of deformable material, for example elastomeric gel, and therefore adapt to the configurations set by the arms 12 and 17.

In practice it has been observed that the intended aim and objects of the present invention have been achieved.

The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept.

All the details may further be replaced with other technically equivalent elements.

In practice, the materials employed, so long as they are compatible with the contingent use, as well as the dimensions, may be any according to requirements.

The disclosures in Italian Patent Application No. PD2000A000076 from which this application claims priority are incorporated herein by reference.