Chairs and seats – Back movement resiliently opposed in operating position – Back and seat adjust simultaneously
Reexamination Certificate
2000-07-05
2003-02-25
Cuomo, Peter M. (Department: 3636)
Chairs and seats
Back movement resiliently opposed in operating position
Back and seat adjust simultaneously
C297S300500, C297S300300, C297S301300
Reexamination Certificate
active
06523896
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to a chair having a seating platform, having a seat carrier that carries the seating platform and is connected to a central chair column or a plurality of chair legs, and having a rest carrier that proceeds toward the back under the seating platform and upward behind the seating platform and carries a backrest, whereby the seating panel, close to its front edge, is hinged to the seat carrier pivotable around a transversely proceeding, first swivelling axis and, offset therefrom toward the back, is hinged to the rest carrier pivotable around a parallel, second swivelling axis, whereby the rest carrier is hinged to the seat carrier pivotable around a third swivelling axis that proceeds between the first and second swivelling axis and parallel thereto, and whereby a compression spring arrangement that exerts a pre-stress force acting upwardly on the seating platform and toward the front on the back rest is provided under the seating platform and is supported thereat.
DE 43 13 301 C2 discloses a chair of the type just described. It is thereby specifically provided that supports that are downwardly directed in pairs are rigidly secured to the underside of the seating platform in the front and back region thereof, whereby the lower ends of the front supports are pivotably connected to downwardly directed guide members pivotably secured to the seat carrier, and the lower ends of the rear supports are pivotably connected to the rest carrier, and that the compression spring-arrangement is arranged between the seating platform and the seat carrier. What is referred to as a synchronous mechanism is achieved with this design of the chair, whereby, when the back part of the seating platform is loaded, the platform is lowered toward the back and the backrest is simultaneously pivoted toward the back, whereby the swivel angle of the backrest is usually greater than the swivel angle of the seating platform. The relationship of the swivel angle to one another is defined by the interacting lever lengths.
What is considered disadvantageous about this known chair is that the pre-stressing force of the back rest is dependent only on the strength of the compression spring arrangement and the lever effect determined in the design of the chair, so that an adaptation of the pre-stressing force of the backrest to different body weights of different users is not possible at all. Although an influencing of the pre-stressing force of the backrest would be possible by employing an adjustable or biasable compression spring arrangement, the user of the chair must manually implement the adjustment for this purpose, which represents an undesirably high outlay, particularly when a chair is used by different users that differ in weight. Moreover, it is not assured that the user will find the suitable setting, as a result whereof settings of the pre-stressing force of the backrest can derive that are incorrect and that may even be harmful to health under certain circumstances.
SUMMARY OF THE INVENTION
An object of the present invention is therefore to create a chair of said species that avoids the disadvantages that have been presented and whereby, in particular, an automatic adaptation of the pre-stressing force of the backrest to users differing in weight is achieved.
The features of the chair that are present in a preferred embodiment of the invention are that the seating platform is moved down given use by a heavy user, this necessarily leading to a tensing of the compression spring arrangement. Since the compression spring arrangement is supported on the extension of the rest carrier, the compression spring arrangement exerts a lever moment on the rest carrier that leads to an increase in the pre-stressing force of the backrest. A chair user having a high body weight thus experiences an increased support of his or her back by the backrest, as is desired and ergonomically meaningful. When a lighter weight user sits on the chair, the seating platform assumes a position that lies further up and wherein the compression spring arrangement is tensed less; correspondingly, a slighter pre-stressing force of the backrest necessarily follows, so that a lighter weight user also experiences an appropriately lesser supporting force of the backrest against his or her back in conformity with the lower body weight. At the same time, however, the synchronous adjustment of seating platform and backrest is preserved to its full extent, so that the seating platform and the backrest are also swivelled in a predetermined relationship relative to one another given changes in the sitting position. Despite the synchronous mechanism and the automatic adaptation of the pre-stressing force of the backrest to different user body weights, the chair has a surprisingly simple design, so that the manufacture of the chair is relatively simple and cost-beneficial.
In order to achieve a compact structure that occupies little space, it is preferably provided that the second swivelling axis proceeds under the seating platform close to the longitudinal center thereof. The mechanism required for the chair movements can thus be concentrated under the front half of the seating platform, which simplifies the manufacture of the chair and which yield an attractive appearance of the chair and, in particular, of its motion mechanism arranged under the seating platform.
It is also provided that the underside of the seating platform comprises at least one respective front and back bearing support through which the first, front swivelling axis and the second, back swivelling axis proceeds. As a result of these bearing supports, the first and the second swivelling axes are lent a desired spacing from the seating platform. Moreover, different seating platforms can be connected to the bearing supports in the simplest way, so that different embodiments and designs of the chair with a different seating platform are possible with little outlay.
A technically simple and, at the same time, functionally dependable solution for achieving the aforementioned vertical motional latitude of the seating platform relative to the seat carrier and/or the rest carrier is comprised therein that the bearing supports each comprise an oblong hole through which a first, front and second, back bearing pin rigidly connected to the seat carrier respectively proceeds, whereby the oblong holes proceed on a radius around the respectively non-appertaining, other bearing pin. As a result of said course of the oblong holes, a swivelling of the seating platform both around the front, first swivelling axis as well as around the back, second swivelling axis is possible without seizing, so that the seating platform can effortlessly adapt to different sitting postures of the chair user.
It is further proposed that, for forming a motion detent of the rest carrier, the second, back bearing pin also proceeds through an essentially vertically directed oblong hole in the rest carrier. Separate means for limiting the movement of the rest carrier are eliminated in this way, this being a further contribution to the simplification of the mechanical design of the chair. At the same time, said oblong hole, in interaction with the second, back bearing pin, serves for coupling the seating platform and rest swivel within the synchronous mechanism.
One embodiment of the chair, which can be preferably employed as an office swivel chair, provides that the seat carrier, proceeding in longitudinal direction of the seating platform, is arranged thereunder in the transverse center thereof, and has its back end connected to the chair column; that a respective rest carrier having a respective, appertaining compression spring arrangement is provided to the left and right of the seat carrier and symmetrically relative thereto; that two respective, front and back bearing supports are present; and that a respective, through, front and back bearing pin is attached to the seat carrier.
An alternative embodiment of the chair, which is essentially suitable as a co
Cuomo Peter M.
Harris Stephanie
Roder Peter
Sonnenschein Nath & Rosenthal
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