"A CHAIR WITH AN ELASTIC, COUNTER-REACTING, RECLINING SEAT BACK' DESCRIPTION This invention relates to a chair as those used to sit at a table (that may be a dining table or other) allowing adaptation, that can be gradual as required, to increase comfort and especially relaxation by means of a maneuver that is particularly simple and easy. Additionally, the chair structure is particularly cost-effective to make, without cumbersome or unsightly components. These and other purposes and advantages will result from the following text.

Essentially, in the chair according to this invention-comprising a frame, a seat and a seat back-the seat back is jointed to the frame at an intermediate height while the front of the seat can slide on the frame and the back of the seat is suspended by means of a joint under the seat back.

A spring-such as, preferably, a traction spring, reacting between the frame and the seat under the seat-stresses the seat in such a way that the seat back is taken to the minimum tilt position with respect to a vertical line.

Spring tension can be adjusted by means of a screw or in another way.

In practice, the front of the seat can slide on two wheels arranged on two respective rolling bars which are part of the frame, the bars being slightly slanted forward and upward. The supports of the wheels or other sliding devices can fasten the lower part of the seat underneath the rolling bars.

Suitable stops limit the movements of the seat and/or the seat back.

This invention will be illustrated with reference to a preferred embodiment as non-limiting examples in the enclosed drawings, whereas: Figure 1 illustrates a side view of the chair with the seat back in minimum tilt position; Figure 2 is similar to Figure 1, but partially in a section view and illustrates the seat back in a more tilted position; Figure 3 is a partial section view according to ttt-ttt of Figure 1 with parts removed; Figure 4 illustrates a local enlarged section according to IV-IV of Figure

2; Figure 5 illustrates a detail of a different form of embodiment.

As illustrated in the enclosed drawing, 1 generically indicates a main supporting frame of the chair with front legs 1A and rear legs 1 B, connecting cross bars such as 1C, 1D, 1E and, in particular, two longitudinal bars 1F which are parallel and symmetric with respect to the longitudinal symmetry plane for the purposes illustrated hereof. The frame and, in particular, the rear legs 1 B present two upward extensions 1 G, which rise by the sides of the seat back 3 of the chair; this seat back is jointed by means of pins 5 to the upper ends of the two extensions 1 G, in such a way that the seat back 3 can rock on the common axis of pins 5, which axis is in an intermediate position with respect to the development of the seat back in height. Reference 7 indicates the seat which is slightly tilted upward and forward, as shown in particular in Figures 1 and 2. The back of the seat 7 is suspended by means of joint hinges 9 (Figures 1 and 2) to the lower end or, in any case, to the lower part of the seat back 3, while the front part of the seat 7 is slidingly supported on the two bars 1 F of the frame 1, which bars are also slightly slanted upward and forward.

Two supports 10, which are part of a stiff component 11 fastened under the seat 7, are arranged on the bars 1 F to support and slide the seat 7 on the bars 1F; each support 10 engages a wheel 12 which can turn, the wheel being contoured advantageously and, in any case, in such a way to allow supporting and rolling on the corresponding bar 1F. The supports 10 are contoured to encompass the lower part of the bars 1 F and prevent the seat 7 from being lifted off the bars 1 F while ensuring that the seat is free to move by effect of the rolling wheels 12 when these wheels are on the bars 1 F; shims 13 (Figure 4) prevent direct contacts between the supports 10 and the bars 1F.

As a result, the seat can essentially move according to the double arrow f7 in a direction approximately corresponding to that of the bars 1 F, seat back 3 tilting on hinges 5 as the seat 7 moves. Consequently, the seat and the seat back can reach different positions, in particular, a series of positions

included between the two extremes delimited, for example, by cross bars 1 D and 1E which correspond, respectively, to the minimum and maximum tilt of seat back 3 with respect to a vertical line. These extremes can be delimited- alternatively-by suitable stops either of the oscillation of the seat back with respect to the frame 1 or of the excursion of supports 10 with respect to the bars 1 F with possibility of adjustment.

A suitable elastic device is arranged to apply stress on the seat and the seat back holding the seat back in the less tilted position with respect to a vertical line, which is the position of the chair for use at a table, such as a dining table or other. In particular, a traction spring 14 may be arranged, the spring being anchored to cross bar 1C and to an appendix 11 A of the component 11 fastened to the seat 7 to pull the seat 7 to its most backward position, i. e. towards the left in Figures 1 to 3. Consequently, the elastic device 14 stresses the arrangement 7,3 in the position shown in Figure 1, while the user of the seat-sitting on seat 7-can push the upper part of the seat back 3 with his back, overcoming the action of the elastic device 14 and the action of gravity, to increase the tilt of seat back 3 with respect to the vertical line in order to reach more and more tilted positions with respect to the vertical line of the seat back 3 to reach the position shown in Figure 2 which is a relaxing position allowed by the chair herein illustrated; during these movements, the seat 7 moves slightly only in the direction approximately of the double arrow f7, with a slight variation in tilt due to the circumferential trajectory of the hinges 9 around the center defined by the pins 5 joining the seat back 3 to the frame 1.

Armrests as those referred to as 16 of any suitable shape mainly engaging the base formed by the frame 1 and the ends of the extensions of the cross bar 1 D of said frame can be fitted on the chair.

In a different form of embodiment illustrated in Figure 5, equivalent parts are indicated with the same references 1C and 14 of the previous example. According to this embodiment, the spring 14 is anchored to the cross bar 1 C in an ajustable fashion so to vary the tension of the spring 14.

The spring 14 is fastened to a hole 40 in a partially threaded rod 42 which can

slide without turning inside a tubular bushing 44 welded to the cross bar 1 C of the frame 1; the rod 42 can present a lengthwise groove 42A in which a prong 44A made on the bushing 44, or welded to it, can penetrate. A knob 46 is arranged and can turn against the end 44B of the tubular bushing 44, the knob being fastened on the threading of the rod 42. The tension of spring 14 can be varied by turning the knob 46.