At the present time, there are known some seats suitable for maintaining the body of a seated person in a correct position but always in movement, that is by forcing said person to have a so- called ergonomic and/or active seat.

A first type of chair is constituted by a support structure, which is leant on to the ground with two vertical arcs equal and parallel to each other, in such a way as to create an oscillating movement, which structure is adapted to support on the upper part of the back end portions of said arcs a seat, in such a way that the same be inclined frontally downward, and on to each one of the front end portions of said arcs there are supported a relative flat element inclined at the back side downward, which is adapted to lean the knees or the feet thereon. To said support structure, it is possible to fix to the back part a seatback that follows the physiological curves of the spine of the person seated thereon.

A second type of chair is constituted by a support structure formed by a cylinder provided with a central vertical through hole, which cylinder is leant on to the ground through small feet or wheels fixed at the lower side along its circumference, and at the back side such a structure is provided with a backseat that follows the physiological curves of the spine of the person seated thereon. In the interior of and on the upper part of the hole of said cylinder it is positioned a ball, with a diameter greater than that one of the hole in such a way that the ball fits therein, thereby remaining stationary, said ball being constituted by a spherical ball made of elastic polymeric material, preferably PVC filled with air or gas in a quantity suitable to confer to it the desired weight strength.

It is easy to note that, with the two above described types of chairs, the persons sitting thereon are staying always in an unstable position, therefore their body must be always activated for finding and staying in a balanced position.

However, such types of seats are very complicated to be manufactured, and require a complicated design and then are very cumbersome and also have very high production and selling costs.

The object of the present invention is to realize a portable device for a seat, adapted to be applied on to any plane onto which a person may seat himself, in such a way that the seat be ergonomic and/or active, and that eliminates the above described problems.

This portable device for a seat is realized with the constructive characteristics that will be described, given by way of a not limitative example only and with reference to the accompanying drawings, in which :

- Fig. 1 shows a perspective view of the portable device for a seat wherein there are visible its substantial component elements, according to the invention ;

- Fig. 2 shows a perspective side view of a first component element of the device of Fig. 1 ;

- Fig. 3 shows a perspective view from top of a first component element of the device of Fig. 1 ;

- Fig. 4 shows a perspective side view of a second component element of the device of Fig. 1 ;

- Fig. 5 shows a perspective view from top of a second component element of the device of Fig. 1;

- Fig. 6 shows a perspective side view of the two component of Figs. 2-5 coupled to each other, in a possible rest position thereof;

- Fig. 7 shows a perspective side view of the two component of Figs. 2-5 coupled to each other, in a first possible working position thereof ;

- Fig. 8 shows a perspective side view of the two component of Figs. 2-5 coupled to each other, in a second possible working position thereof ;

- Fig. 9 shows the device of Fig. 1 in a first working position thereof ;

- Fig. 10 shows the device of Fig. 1 and 9 in a further working position thereof .

The present invention relates to a portable device for a seat, adapted to be applied on to any plane onto which a person may seat himself, in such a way that the seat be ergonomic and/or active. As it is visible in the Fig. 1, such a portable device for seat 10 is constituted substantially by a first support component element 11, a second support component element 12 and a third containing element component 13, adapted to contain said first and second component elements.

Said first and second component elements 11, 12 are both made of stiff material, such as for example wood or plastic material.

By referring to the Figs. 2, 3, it is noted that the first support element 11 is constituted by a flat body 14, preferably with a circular base, having two horizontal flat surfaces, upper 17 and lower ones 17' joined to each other by two joining parts, upper 15 and lower one 15', and of which one of two said surfaces 17, 17' is provided centrally with a small curved hollow 16.

By referring to the Figs. 4, 5, it is noted that the second support component element 12 is constituted by a flat body 18 with shape and dimensions identical to the ones of the first flat body 14, having two horizontal flat surfaces, upper 21 and lower 21 'ones, joined to each other by upper and lower joining parts 19, 19', and of which one of the two surfaces 21, 2 is provided centrally with a semi-sphere 20.

Such first and second component elements 11, 12 are coupled to each other in such a way that the external end portion of the semi- sphere 20 be into contact with the curved hollow 16, so that the two component elements be arranged coaxial to each other, as it is show in the Figs. 6-8.

So coupled to each other, the two component elements 11, 12 are inserted into the third containing component element 13, constituted by a container 22 with a shape identical to the base of the two flat bodies 14, 18, which is made of soft material, such as for example cloth or rubber, and provided with a side opening 23 that may be closed by a zipper or Velcro or the like, adapted to the introduction and the removal of said two elements 11, 12 coupled to each other.

Such a cylindrical container 22 has also such a diameter and height that the two first and second component elements 11, 12 may not be uncoupled to each other when they are introduced in the interior of said container, but however they are independent to each other during the oscillating movements determined by coupling the semi-sphere 20 and the curved hollow 16, as it is shown in the Figs. 9 and 10.

Said portable device for a seat 10, assembled in the above manner, once it is resting by means of one of the external horizontal surfaces 17 or 21 of one of the two support elements 11, 12 on to any support plane, such as for example a seat of a chair, a stool, an arm-chair, or on to the floor, or on to the upper plane of a small wall, a pedestal, a cut tree trunk, etc..., is arranged with the support element 11 or 12 positioned on the upper part that, thanks to the instability provided by coupling the sphere 20 and the hollow 16, tends to stay oblique, by resting with a part of its external circumference onto the external circumference of the other support element positioned in the lower position.

A person who seats himself onto the support element 11 or 12 positioned on the upper part of the device 10 arranged onto said support plane, with the other its support element 11 or 12 positioned in a lower position, is capable of obtaining an active seat when is trying to balance himself, in such a way that the two support elements 11 and 12 be positioned and remain parallel to each other (See Figs. 7, 8, 10), or the person is capable of obtaining an ergonomic seat for facilitating the posture during the seating phase, by inclining frontally the support element 11 or 12 that is arranged in the upper part and by letting it to rest in front of the other lower support element 11 or 12 (See Figs. 6, 9), so that the weight of the body of the same seated person be unloaded both on to the back bottom and on to the legs, thereby unloading the spine thereby maintaining a correct curvature and position of the physiological curves of the same spine, or is capable of obtaining a relaxed seat by inclining the upper support element 11 or 12 backward, so that this latter rests on to the back part of the other lower support element 11 or 12 (See Figs. 6, 9), in such a way that the back of the same seated person rests on to the possible seatback and the weight of the entire body be distributed mainly along the entire spine. Consequently, one can note that with the present portable device for a seat, it is possible to obtain advantageously an ergonomic and/or active seat everywhere there is a plane, therefore without being in possession of one of the types of chairs known until now and described in the preamble of the present description and having the above mentioned drawbacks.

Finally, one stuffing element 25 may be positioned onto one or both the external surfaces 17 and/or 21 for increasing the seating comfort, that consequently is also contained into the containment element 13.