Chairs and seats – Back movement resiliently opposed in operating position – Back and seat adjust simultaneously
Reexamination Certificate
2000-06-19
2003-02-04
Mai, Lanna (Department: 3635)
Chairs and seats
Back movement resiliently opposed in operating position
Back and seat adjust simultaneously
C297S300400, C297S298000, C297S320000
Reexamination Certificate
active
06513874
ABSTRACT:
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The invention relates to a chair, in particular an office chair, having a backrest which is arranged such that it can be rotated about a first point of rotation in relation to a seat carrier and which can be inclined from a rest position, and having a seat surface which is connected to the backrest such that it can be rotated about a second point of rotation and which can be inclined synchronously with the backrest.
Such a chair is known, for example, from European Patent Application EP 0 888 739 A2. In the known chair, both the backrest and the seat surface, which is connected rotatably thereto, are designed such that they can be inclined rearward from a rest position. The inclination movement, which runs in a vertical movement plane, is controlled by a linkage in the form of a quadrilateral linkage as a guide mechanism. In this case, a seat carrier, which is connected to a stand, forms a base link and a seat surface, which runs above said seat carrier, approximately parallel thereto, forms a seat link.
At their ends, said links are connected to one another in each case via a front link and a rear link for the purpose of forming the quadrilateral linkage. In this case, as far as the inclination movement is concerned, the rear link is fixed to the backrest, with the result that the first point of rotation is provided by the axis of rotation between the seat carrier or base link and the rear link. Correspondingly, the second point of rotation is provided by the axis of rotation between the rear link and the seat surface or the seat link.
Similarly, in a chair known from EP 0 250 207 B1, the inclination movement of the backrest and the seat surface, which is guided synchronously therewith, is controlled via a quadrilateral linkage. In this chair, the quadrilateral linkage, which controls the inclination movement of the chair, is subjected to the action of a pneumatic spring, which has its ends articulated on the front articulation of the seat link and on the stand, in order to move the seat link back in each case from a rearwardly inclined position into the rest position.
PCT WO 83/00610 also discloses a chair of the type mentioned in the introduction. In this chair, the guide mechanism provided for the inclination movement is likewise a linkage, but in this case in the form of a slider crank, that is to say a three-bar linkage with two rotary articulations and with a rotary/sliding articulation. In this chair too, a pneumatic spring moves the seat link back in each case from a rearwardly inclined position into the rest position. For this purpose, the compression spring, which has one end articulated on the stand or seat carrier, has its other end acting on the rear articulation of the seat link, where the latter is connected to the rear link, which bears the backrest.
SUMMARY OF THE INVENTION
The object of the invention is to develop a chair of the abovementioned type such that a particularly pronounced inclination movement of the backrest with an inclination of, for example, up to 40°—in relation to the starting position of the backrest—is also made possible without the chair tilting rearward via its center of gravity. Furthermore, it is also the intention, even if the backrest is inclined to a particularly great extent of more than 40°, to avoid as far as possible the situation where an individual seated on the chair feels as if he/she is about to topple over.
This object is achieved according to the invention in that, in the rest position, the first point of rotation is positioned at approximately the same height as, or higher than, the second point of rotation.
The invention takes as its departure point the consideration that, in the known chair, the tendency to tilt is promoted, and the angle of inclination which can be achieved by the backrest is thus reduced, in that, as the backrest is inclined rearward, the center of gravity of the chair is likewise displaced rearward to a particularly pronounced extent. This is accentuated, in particular, in that, as the backrest is inclined rearward and downward, the seat surface, which is guided synchronously therewith, is likewise displaced rearward. For just a low tendency to tilt, the chair should thus be designed such that, even as the backrest is inclined rearward to a relatively pronounced extent, the center of gravity is displaced rearward only to a slight extent. Rearward displacement of the center of gravity can be kept to a particularly low level in that, as the backrest is inclined rearward, the seat surface is displaced synchronously forward rather than rearward. This is achieved by the abovementioned arrangement of the first and second points of rotation relative to one another.
The chair is advantageously designed such that, as the backrest is inclined rearward and downward, the second point of rotation moves forward and downward. A rearward and downward inclination of the backrest is accompanied by a forward displacement of the seat surface and lowering of the same. As seen in relative terms, in this case, the first point of rotation (which is stationary in relation to the seat carrier) moves upward in relation to the seat surface, whereas this second point of rotation moves downward in the direction of the seat carrier. Such an arrangement can achieve a particularly comfortable movement sequence during the inclination for the individual using the chair.
In addition, for a particularly straightforward construction, the chair is expediently designed such that the second point of rotation is located level with the seat surface and thus the axis of rotation between the seat surface and backrest, said axis of rotation being defined by said point of rotation, is located in the seat surface.
In a further advantageous configuration, the first point of rotation is located higher than the bottom edge of the seat surface. In addition, for a particularly comfortable feeling of movement for the individual using the chair, a further expedient configuration provides, in the rest position, for the second point of rotation, for appropriate adaptation to the points of rotation in the body, to be arranged approximately beneath a position provided for the ischial tuberosities of the seated individual.
In a particularly, advantageous configuration, the chair is designed such that, as far as the inclination movement is concerned, the synchronism ratio between the seat surface and backrest is approximately 1:3. As the backrest is inclined by approximately 40° in relation to its starting position, this gives an inclination of the seat surface of approximately 13° or 14° in relation to its starting position, the inclination advantageously resulting from a corresponding lowering of the seat surface.
For a design which is particularly favorable in terms of ergonomics, the seat surface, in particular in terms of its dimensions in relation to the position of the first and second points of rotation, is expediently dimensioned such that, as the backrest is inclined rearward and downward, the front edge of the seat surface moves forward and downward.
For a mechanical support and in order to allow the inclination movement of the seat surface, said seat surface is expediently connected to the seat carrier such that it can be rotated about a third point of rotation. In order to allow the forward and downward movement of the seat surface provided during the inclination movement of the backrest, the third point of rotation is expediently guided positively. The positive guidance is advantageously such that, as the backrest is inclined rearward and downward, the third point of rotation moves forward and downward. The positive-guidance dimensions make it possible to adjust the synchronism ratio between the seat surface and the backrest as well as the extent of the forward movement of the seat surface during the inclination of the backrest.
For a particularly straightforward construction, a slotted guide is provided for the positive guidance of the third point of rotation. In this case, an axis of rotation
Potrykus Martin
Sander Armin
Greenberg Laurence A.
Konig & Neurath AG
Locher Ralph E.
Mai Lanna
Stemer Werner H.
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