Folding chair with continuously variable self-balanced tilting action

Abstract: Chair comprising a seating unit (1) and two pairs of legs (4,6) made slidingly integral by means of couplings (2,3) attached to seating unit (1) and designed to engage the relevant inserts (4a,4b) located in such first pair of legs (4), which are made to slide in relation to the second pair of legs (6) by further couplings (7) located in further inserts (4c) provided on such legs (4), such couplings being designed to allow substantially continuous tilt adjustment of the seat and of the backrest relative to the seat, as a result of the relevant pushing action exerted by the user, the various positions assumed being stably balanced by the same action which has determined them.

Description: The object of this invention is to provide a folding chair especially intended for office use, designed for continuous tilt adjustment of the seat and backrest to assume at all times stable settings automatically balanced by the same action which has brought about such adjustment. It is known that there is an increasing need to alter the setting of chair, armchair and similar seats in relation to the various positions assumed by the user throughout the day. In the office environment particularly, following the widespread introduction of computer and word processing systems on desks, it is necessary to provide a chair enabling a comfortable and ergonomically correct position to be achieved both when writing normally at a table or desk and when using a computer keyboard, such keyboards usually being placed in a lower position relative to the desk top; it is also necessary to provide a slight backward tilt to the so-called active rest position. It is also known from DE-A-38 22 877 a non foldable chair able to change the position of the backrest in relation to the legs from an upper position to a reclined position. There is therefore posed the technical problem of developing a chair capable of allowing forward swivel of the seating unit as well as controlled swivel of the backrest relative to the seat so that the user may assume either a more favourable position far writing and/or typing or a slight backward tilt to the rest position. A further aim of this invention is to provide a chair capable of allowing substantially continuous adjustments to the setting of the seat and backrest as a result of the different positions assumed by the user at various times. The chair should moreover be of extremely compact dimensions and comprised of a small number of parts capable of being easily assembled and dismantled to facilitate routine or special maintenance tasks, and it should be capable of being folded when not in use in order to reduce its overall dimensions and facilitate both storage in a concealed position by the user and warehousing and transport by the manufacturer. Such results are obtained from the present invention as defined in independent Claim 1, with preferred embodiments defined in dependent claims 2 to 8. Further details will be apparent from the following description, with reference to the attached drawings in which are shown: In figure 1 : a perspective view in oblique projection of the chair according to the invention; In figure 2 : a partial diagrammatic section on plane II-II of figure 1; In figure 3 : a side view of the chair in fig. 1; In figure 4a: the chair in fig. 1 tilted forward; In figure 4b: the chair in fig. 1 with its backrest tilted rearward; In figure 5 : a diagrammatic side view of the chair in fig, 1 with the various movements depicted by broken lines and dotted lines for seat and backrest tilt respectively; In figure 6 : the chair in fig. 5 mounted on wheels; In figure 7 : an alternative version of the chair in fig. 1, and In figure 8 : a further alternative version of the chair in fig 1. As shown in figure 1, the chair according to the invention is substantially comprised of a seating unit 1 consisting of a slablike member folded along a curved line 1c to provide a substantially vertical backrest 1a and a substantially horizontal plane of seat 1b. Such seat 1b and backrest 1a are made rotationally integral with one another by means of a pair of hinges 100 consisting of two arms 100a and 100b respectively attached to backrest 1a and seat 1b. More particularly, the upper end of each arm 100a ends in a circular insert containing a pin 2 partly protruding from the edge of backrest 1a, whilst there protrudes from seat 1b the swivel pin 3 of hinge 100. Such pins 2 and 3 are designed to be inserted in a known manner into the appropriate slots 4a and 4b of a first pair of legs 4, located obliquely relative to seating unit 1 which are thus made slidingly integral with both backrest 1a and seat 1b; such legs 4 are then joined together by a crossbar 4d to form a substantially H-shaped first frame. Slots 4a and 4b are furthermore respectively located as follows: the first 4a is substantially inclined upward and rearward, and the second 4b is substantially vertical. The lower surface of the front end of seat 1b is moreover supported on a crossbar 6' for the attachment of a further pair of legs 6, the assembly of which forms a substantially "inverted U"-shaped second frame, linked in a sliding manner to seat 1b by means of a rail 5a or similar made integral with the lower surface of seat 1b and in which slides crossbar 6'. Legs 6 of such second pair are likewise linked in a sliding manner to the first pair of legs 4 by means of pins 7 inserted in a known manner into slots 4c which are provided in appropriate positions on legs 4. As is apparent from figures 1 and 2, the chair as used under normal conditions has its seat 1b located substantially horizontal, its backrest 1a substantially vertical and pins 2, 3 and 7 positioned respectively at the inner, lower and upper ends in slots 4a, 4b and 4c. When the user wishes to change his position he shifts his own centre of gravity so as to exert, with his own weight, a pushing action on the front end of seat 1b, thus bringing about a corresponding action on pins 7 which slide towards the lower end of slots 4c, whilst swivel pins 3, constituting the neutral axis, maintain their position relative to the lower end of slots 4c. On the other hand, should the user wish to assume an active rest position with the backrest tilted rearward, it will be sufficient to exert pushing action on backrest 1a which, rotating on pins 3 of hinge 100, will tilt rearward to shift pins 2 from the front end setting to the rear end setting of slot 4a and pins 3 themselves to the upper end setting of slot 4b. For a better understanding, figure 5 shows the various positions which may be assumed by the chair, namely: normal position with seat 1b horizontal and backrest 1a vertical, indicated by a continuous line; working position with seat 1b tilted forward but no change in the relative position of backrest 1a and seat 1b, indicated by a broken line; rest position with seat 1b horizontal and backrest 1a tilted rearward, indicated by a dotted line. It is furthermore apparent that pins 2, 3 and 7 may be positioned, within the relevant slots 4a, 4b, 4c, in any intermediate setting between the two end settings, as a result of the pushing action exerted by the user; all the settings are stable since they are balanced by the user's own weight and by the position assumed by his centre of gravity. The chair according to the invention may also be folded after use, to be placed, for example, in a less conspicuous position or in a cupboard; in order to reduce its overall dimensions seat 1b is swivelled clockwise, whereupon it moves upward and causes pins 5 to slide within guides 5a toward backrest 1a, thus causing legs 6 to swivel on pins 7 and to close in a position parallel to legs 4, whilst seat 1b is folded onto the backrest thus substantially reducing the chair to a parallelepiped the thickness of which is substantially contained within the width of legs 4. Figure 6 shows a first alternative version of the chair according to the invention in which the entire supporting structure is mounted on a column 8 which in turn is mounted on a star base (9) fitted with castors 10. In this case the lower ends of legs 4 and 6 are, in a known manner not described herein, made integral with column 8 by means of hinges 9a to enable backrest 1a and seat 1b to assume the same various positions previously described. Figure 7 shows in turn a second alternative version of the chair according to the invention in which legs 4 and 6 are replaced by a frame 104, substantially of channel section, with a first end still hinged at 5 and a second end extended upward and rearward to form an arm 110, which still includes slots 104a and 104b between which slide pins 2 and 3. In this case also it is possible to adjust both the rake of backrest 1a rearward and, in a limited manner, the forward tilt of seat 1b by elastic deformation around link 107, the movement of the pins within the slots being entirely similar to that previously described for the chair in fig. 1. The chair in fig. 7 may also be provided with two flat members constituting the sides of an armchair still made integral with seating unit 1 by means of pins 2, 3 and slots 4a, 4b, the operation required for tilt adjustment remaining unchanged. Figure 8 shows a further alternative version of the chair in which backrest 1a and seat 1b form a one-piece shell of suitable section to enable backrest 1a to swivel relative to seat 1b. In this case the chair can no longer be folded but seat adjusting movements can still be carried out as shown in figure 5. It is therefore apparent that the chair according to the invention makes it possible to obtain different settings of the seat and of the backrest as a result of the different positions assumed by the user and that such settings, which can be substantially adjusted in a continuous manner, are all substantially stable because they are balanced by the action exerted by the actual user. Many alternatives may be introduced in the technical development of the constructional details of the chair according to the invention without thereby departing from the scope thereof as defined in the appended claims. In particular, it will be possible to altar the length and arrangement of the various slots in order to change the extent to which the seat and backrest can be moved from the rest position and/or the higher or lower sliding friction of the pins in the slots determining the dynamic characteristics of movement, i.e. the greater or lesser ability of the chair to adjust the settings of the seat and backrest.

Claims: Chair of the type comprising a seating unit (1) consisting of a seat (1b), a backrest (1a) and first and second pairs of legs (4, 6) in which said seat and backrest are rotationally joined to one another by means of hinges (100) and in which said pairs of legs (4, 6) and said seating unit (1) are slidingly joined to one another by means of couplings (2, 3) attached to said seating unit (1) and engaging appropriate inserts (4a, 4b) located in said first pair of legs (4) whereby further couplings (7) integral with said second pair of legs (6) and engaging further relative inserts (4c) located in said first pair of legs (4) are provided and in that said inserts (4a, 4b, 4c) substantially consist of slots made in the said first pair of legs (4), the first slot (4a) extending in a substantially oblique direction on the upper end of the legs and the other slots (4b, 4c) extending in a substantially vertical direction on the central upper part of said first legs, there being also provided means of guidance (5a) for the sliding of said second pair of legs (6) in relation to the said seat (1b), said combination allowing a substantially continuous tilt adjustment both of said seat (1b) and of said backrest (1a) relative to said seat (1b) as a result of the relevant pushing action exerted by a user, as well as opening and closing of the actual chair. Chair according to claim 1 characterised in that said couplings are substantially comprised by first and second pins (2, 3) respectively integral with said backrest (1a) and said seat (1b) and projecting therefrom in a substantially horizontal direction, said first pin (3) constituting also the swivel pin of said hinge (100), the upper arm of which has its end rotationally integral with said second pin (2). direction. Chair according to claim 1 characterised in that said second pair of legs (6) is connected by a crossmember (6') the end of which is of "inverted U" shape, such crossmember being capable of sliding within guides (5a). Chair according to claim 1 characterised in that said first and second pairs of legs consist of a channel section structure (104) the upper free ends of which are respectively joined with said seat (1b) and backrest (1a). Chair according to claim 1 characterised in that said second pair of legs (6) consists of a flat member of inverted "U" shape. Chair according to claim 1 characterised in that said second pair of legs (4) has upper ends joined to the front end of said seat (1b) by means of hinges (5) of substantially horizontal axis. Chair according to claims 1 and 6 characterised in that said second pair of legs consists of two flat members constituting the sides of the chair or similar. Chair according to claims 1 and 6 characterised in that said seating unit (1) consists of a one-piece shell curved to form the seat (1b) and backrest (1a). Chair according to claim 1 characterised in that said first and second pairs of legs (4,6) have lower supporting ends hinged to a vertical support (8) integral with a star base (9) running on castors (10).

Inventors: KAUFMAN YAACOV, KAUFMAN, YAACOV
Applicants: KAUFMAN YAACOV, KAUFMAN, YAACOV
Application year: 1991
Main classification: A47C1
IPC codes: A47C4, A47C1, A47C3