Chair, in particular office chair

Abstract

Chair, more especially an office chair, comprising a seat plate (34) which is arranged on an undercarriage (12) and a backrest (14) which in the manner of a so called synchronous mechanism permit a synchronous movement of seat plate (34) and backrest (14), characterized in that the seat plate (34) is mounted laterally tiltable and the backrest includes two backrest supports (22, 24) whose lower ends are mounted pivotally independently of each other on the undercarriage (12) and are coupled in movement to the seat plate (34) in such a manner that by rearward pivoting of the support (22, 24) one side of the seat plate (34) is pressed down on the same side and the opposite side thereof is raised.

Claims

1. An office chair (10), comprising: a seat plate (34) which is arranged on an undercarriage (12); a backrest (14); and a synchronous mechanism permitting a synchronous movement of the seat plate (34) and the backrest (14), wherein the seat plate (34) is mounted laterally tiltable about a longitudinal tilt axis (B) that extends in a forward direction from the backrest, and the backrest includes two backrest supports (22, 24), the backrest supports having lower ends that are mounted pivotally independently of each other on the undercarriage (12) and are coupled in movement to the seat plate (34) in such a manner that by rearward pivoting of one of the supports (22, 24) a first side of the seat plate (34) is pressed down so as to be tilted about the tilt axis (B) to a position below the tilt axis (B) and a second side opposite the first side is raised to a position above the tilt axis (B), wherein a tilt shaft extends in a longitudinal direction along tilt axis (B) for the lateral tilting of the seat plate (34) and lies in a vertical plane between the backrest supports (22, 24).

2. The office chair according to claim 1, wherein the lower ends of the backrest supports (22, 24) are connected pivotally about a common horizontal pivot axis (A) to a base (20) of the undercarriage (12).

3. The office chair according to claim 2, wherein on the first side and the second side beneath the seat plate (34), a set of bearings (44) are provided in which the lower ends of the backrest supports (22, 24) lie in a region behind the pivot axis (A) thereof.

4. The office chair according to claim 3, wherein the seat plate (34) is pivotal together with the lower ends of the backrest supports (22, 24) about the pivot axis (A) thereof.

5. An office chair, comprising: a seat plate (34) which is arranged on an undercarriage (12); a backrest (14); and a synchronous mechanism permitting a synchronous movement of the seat plate (34) and the backrest (14), wherein the seat plate (34) is mounted laterally tiltable about a tilt axis (B) and the backrest includes two backrest supports (22, 24), the backrest supports having lower ends that are mounted pivotally independently of each other on the undercarriage (12) and are coupled in movement to the seat plate (34) in such a manner that by rearward pivoting of the support (22, 24) a first side of the seat plate (34) is pressed down so as to be tilted about the tilt axis (B) and a second side opposite the first side is raised, wherein the lower ends of the backrest supports (22, 24) are connected pivotally about a common horizontal pivot axis (A) to a base (20) of the undercarriage (12) and wherein a tilt shaft extends along tilt axis (B) for the lateral tilting of the of the seat plate (34) and lies in a vertical plane between the backrest supports (22, 24), wherein on the first side and the second side beneath the seat plate (34), a set of bearings (44) are provided in which the lower ends of the backrest supports (22, 24) lie in a region behind the pivot axis (A) thereof, wherein the seat plate (34) is pivotal together with the lower ends of the backrest supports (22, 24) about the pivot axis (A) thereof wherein in a rear region of the undercarriage (12) a bearing member (36) is mounted which is tiltable about the pivot axis (A) of the backrest supports (22, 24) and supports a tilt shaft aligned along the tilt axis (B) of the seat plate (34).

6. The office chair according to claim 5, wherein the seat plate (34) is arranged in a rear region of the seat surface and in a front region of the seat surface a front seat plate (32) is arranged, the front seat plate (32) having opposing sides, wherein a leg springs (48) extends rearwardly from each of said sides to support the rear seat plate (34) on both of the sides from below.

7. The office chair according to claim 6, wherein the front seat plate (32) is carried by a front bearing member (50), the front bearing member having a rear end that is articulately connected to a front end of the bearing member (36), the front bearing member having a front end that is articulately connected to the front end of the base (20) lying therebelow via a connection member (52) which in its rear end receives the horizontal pivot axis (A) of the supports (22, 24).

8. The office chair according to claim 1, wherein the lower ends of the backrest supports (22, 24) are formed by legs (30) angled forwardly in an L shape, the legs (30) having front portions (38) which are connected pivotally about substantially vertically directed axes (C) of rotation to the respective support (22, 24) and the legs (30) having front ends which accommodate the horizontal pivot axis (A) of the supports (22, 24).

9. An office chair, comprising: a seat plate (34) which is arranged on an undercarriage (12); a backrest (14); and a synchronous mechanism permitting a synchronous movement of the seat plate (34) and the backrest (14), wherein the seat plate (34) is mounted laterally tiltable and the backrest includes two backrest supports (22, 24), the backrest supports having lower ends that are mounted pivotally independently of each other on the undercarriage (12) and are coupled in movement to the seat plate (34) in such a manner that by rearward pivoting of the support (22, 24) a first side of the seat plate (34) is pressed down and a second side opposite the first side is raised, wherein the backrest supports (22, 24) are connected in an upper region by a transverse member (54), the transverse member having ends that are articulately connected to the backrest supports (22, 24), the ends forming connection points (56, 58) between the backrest supports (22, 24) and the transverse member, wherein a spacing is defined between the connection points (56, 58), the articulate connection of the transverse member to the backrest supports (22, 24) keeping the spacing between the connection points (56, 58) constant without otherwise restricting a relative movement of the backrest supports (22, 24) with respect to each other.

10. The office chair according to claim 9, wherein the transverse member (54) is formed as a rod with variable length for adjusting the spacing between the connection points (56, 58) at which the rod (54) is connected by ball joints (60) to the backrest supports (22,24).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a perspective view of an office chair illustrating a preferred embodiment of the present invention;

(2) FIGS. 2 and 3 show the office chair or FIG. 1 in different positions;

(3) FIG. 4 is a side view of the office chair according to the present embodiment in a position corresponding to FIG. 1;

(4) FIG. 5 shows the office chair in a side view on assuming a position corresponding to FIG. 2;

(5) FIGS. 6, 7 and 8 are rear views of the office chair of the preceding Figures;

(6) FIG. 9 is a detail view of the mechanism of the present preferred embodiment of the office chair according to the invention; and

(7) FIG. 10 is an exploded view of some of the mechanical components illustrated in FIG. 9.

DETAILED DESCRIPTION

(8) The chair illustrated in FIGS. 1 to 7 is an office chair 10 which comprises in conventional manner an undercarriage 12 which bears a seat surface, and a backrest 14 which is mounted at the rear side of the chair 10. The terms front and rear as well as lateral are with reference to the usual position of use of the chair. The undercarriage 12 is provided in usual manner with a ring of rollers 16 which are mounted on arms extending from a vertically adjustable central column 18. The components of the undercarriage 12 are known and are not part of the present invention.

(9) Mounted at the upper end of the central column 18 is a substantially plate-shaped base 20 of the undercarriage 12, said base being connected to further movable components of the chair 10. The backrest 14 is pivotally connected to the rear end of the base 20 so that the backrest 14 can be pivoted rearwardly with respect to the rear end of the base 20 as is illustrated in FIGS. 2 and 5. The pivot axis of the backrest 14 is designated in the drawings by the letter A. The axis A extends horizontally in the transverse direction of the chair 10.

(10) The backrest 14 includes in detail two backrest supports 22, 24 which are connected by a common backrest surface 26. Said backrest area 26 has a certain elasticity which does not fundamentally impair the pivoting of the two backrest supports 22,24 on both sides of the chair 10 but merely somewhat limits the pivoting range. This does not impair the function according to the invention of the chair 10.

(11) The backrest supports 22, 24 on both sides of the chair 10 are mounted on separate pivot bearings on the horizontal pivot axis A. Said pivot bearings are located at the rear side of the base 20 directly adjacent each other, as will be explained in more detail hereinafter, but on the common axis A. The supports 22, 24 can thus assume different angles of inclination. Each of the supports is formed substantially

(12) L-shaped and has a rear vertical leg 28 and a lower leg 30 which in FIGS. 1 and 4 is substantially horizontal and the front end of which leads to the respective pivot bearing. The length of the horizontal leg 30 provides a rearward offsetting of the backrest surface 26 with respect to the seat surface and the axis A and thus for an adequately comfortable sitting position. Moreover, it is obvious that the backrest area 26 can be cushioned or configured in any other desired manner to ensure adequate sitting comfort.

(13) The seat area of the chair 10 is formed by two seat plates, that is a front seat plate 32 arranged at the front edge of the chair 10 and a rear seat plate 34 located between the front seat plate 32 and the backrest 14. Whereas the front seat plate 32 is substantially stationary, the rear seat plate 34 is movable to a great extent, as will be explained in detail hereinafter. It is disposed above the horizontal pivot axis A and bridges the entire width of the seat surface.

(14) On a rearward inclination of the backrest 14 the rear seat plate 34 is tilted rearwardly and downwardly, as can be seen clearly in FIGS. 2 and 5. The seat plate 34 thus follows the movement of the backrest supports 22, 24 and is coupled in movement to the latter. Thus, like the backrest 14 the seat plate 34 is pivoted about the horizontal pivot axis A.

(15) The perspective rear view in FIG. 9 and the exploded illustration in FIG. 10 show how the seat plate 34 is coupled in movement to the backrest supports 22, 24. The seat plate 34 is mounted laterally tiltable, i.e. in the left-right direction, about a tilt axis B. The tilt axis B extends directly beneath the actual seat area and lies in a vertical symmetry plane of the chair 10 which in turn is perpendicular to the horizontal pivot axis A of the backrest 14. In the inoperative position of the chair in FIGS. 1, 4 and 7 the tilt axis B is horizontal.

(16) The seat plate 34 is mounted tiltable about the axis B on a bearing member 36 which itself is tiltable about the pivot axis A. The seat plate 34 is therefore pivotal both about the horizontal axis A and about the tilt axis B, The tilt axis B is itself tilted out of the horizontal position when the bearing member 36 is pivoted about the pivot axis A.

(17) The articulate connection between the backrest supports 22, 24 and the stationary part 20 of the undercarriage 12 is effected via front portions 38 of the forwardly angled legs 30 of the supports 22, 24. These front portions 38 are formed as pairs of plates 40, 42 (see FIG. 10) which are arranged parallel above each other and which enclose from above and below the forwardly directed ends of the remaining portions of the horizontal legs 30. As can be seen in particular in FIG. 7 the front portions 38 are articulately connected to the remaining portion of the respective support 22, 24, this being done via vertically disposed rotation axes C. In particular the vertical legs 28 of the supports 22, 24 are thus pivotally mounted at the rear side of the chair 10. The horizontal pivot axis A of the backrest 14 extends through the front ends of the portions 38.

(18) Provided on both sides beneath the seat plate 34 are bearings 44 which are configured as members formed L-shaped at the underside of the seat plate 34. The horizontal legs of these members point towards each other and engage laterally into the portions 38 between the upper and lower plates 40 and 42. The upper plates 42 thus lie in the bearings 44, that is on pads 46 provided there for dampening.

(19) Since the portions 38 can be pivoted independently of each other about the axis A, on the two sides of the chair 10 a different pressure can be transmitted via the bearing means 44 to the seat plate 34 and this leads to the seat plate 34 being tilted laterally about the tilt axis B due to this one-sided load. If for example in accordance with FIGS. 3 and 7 the right backrest support 22 is pivoted rearwardly, its horizontal leg 30 will be pressed downwardly. When this happens, via the upper plate 42 the front portion 38 of the leg 30 exerts a pressure on the on the right bearing member 44 of the seat plate 34 so that said seat plate 34 is pressed down on this side whilst the opposite left side of the seat plate is raised. In other words the rearward pivoting of a support 22, 24 on one side of the chair 10 involves a pressing down of the rear seat plate 34 on the same side and a raising of the opposite end of the seat plate 34 on the other side. The backrest supports 22, 24 hereby assume different inclination positions. FIG. 8 shows the situation when a pressure is exerted on the left side of the seat plate 34.

(20) The unilateral lowering of the seat plate takes place against the pressure of one end of a leg spring 48 which extends laterally rearwardly from the front seat plate 34 and on which the respective end of the rear seat plate 34 is mounted. Thus, the seat plate 34 on reduction of the pressure from above has the tendency to return to its horizontal position.

(21) According to FIG. 10 a central part of the leg spring 48 is mounted in a front bearing member 50 which also carries the front seat plate 32 and is formed integrally with the latter. The rear end of said front bearing member 50 is connected pivotally about a horizontal pivot axis D to a front end of the bearing member 36 which carries the rear seat plate 34. At its front end the front bearing member 50 is articulately connected via a connector 52 to the front end of the base 20, lying therebelow, of the undercarriage 12. The articulation axis for connecting the front upper end of the connector 52 to the front bearing member 50 is denoted by the letter E whilst the articulation axis between the connector 52 and the base 20 is denoted by F. The axes A, D, E and F define a quadrilateral which approximately forms a parallelogram. This construction effects that on tilting of the bearing member 36 together with the rear seat plate 34 a tensile force is exerted on the front bearing member 50 with the front seat plate 32 and the latter is slightly raised, as becomes clear on comparison of FIGS. 4 and 5. The front seat plate however retains its horizontal position here.

(22) Although the lower ends of the backrest supports 22, 24 are mounted independently of each other about the pivot axis A, in their upper region the supports 22,24 are coupled in movement; this is done according to FIGS. 6 to 9 by a transverse member 54 whose ends 56, 58 are articulately connected to the vertical legs 28 of the supports 22, 24 at about half the height of the backrest 14. This articulate connection is by ball joints 60. The transverse member 54 ensures that the distance between the connection points 56, 58 to the supports 22, 24 is kept constant without otherwise restricting the movement of the supports 22, 24 relative to each other. In particular, the pivoting of the supports 22, 24 in opposite directions remains possible. The transverse member 54 here assumes an inclined position and the vertical legs 28 of the supports 22, 24 can come closer to each other. This is made possible by a slight pivoting of the rear portions of the supports 22, 24 about the vertical pivot axes C with respect to the front portions 38.

(23) In the movement sequence described above during the use of the chair 10 the distance between the articulation points of the transverse member 54 remains constant. However, the length of the transverse member 54 can be adjusted by the user employing a suitable mechanism so that the tension between the backrest supports 22, 24 is variable, This mechanism may for example include a spindle drive inside the transverse member 54.