Chairs and seats – Back movement resiliently opposed in operating position – Back adjusts independent of seat
Patent
1999-04-13
2000-11-21
Nelson, Jr., Milton
Chairs and seats
Back movement resiliently opposed in operating position
Back adjusts independent of seat
2973011, A47C 1024
Patent
active
061492361
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a chair, in particular a swivel chair for the office, with a height-adjustable seat surface and a backrest which can be adjusted in terms of inclination and is articulated in the plane of the seat surface so as to provide a fixed region for the thigh support and pivotable region for the posterior support. This gives a pivot axis which runs over the width of the seat surface and is obtained by articulation connections on the frame. The padded covering of the seat surface extends from the front edge to beyond the pivot axis. The entire chair mechanism is arranged beneath the seat. Both the height adjustment and the inclination adjustment are realized by means of springs, preferably pneumatic springs, arranged in the frame. In order to optimize the inclination-movement sequence and to set a level of prestressing along with the pneumatic spring, it is common practice to provide an additional helical compression spring. The pneumatic springs are actuated via adjusting levers which are positioned beneath the seat surface and to which the user has access when seated
Depending on the previous position of the spring used for the inclination, the actuation of said spring either locks the current position of the back rest, which is lengthened, as it were, up to the pivot axis in the seat surface, or cancels the locking action. Once the locking action of the inclination adjustment has been released, it is possible for one to change the position of the backrest within an adjustment range by shifting one's body weight, the posterior support following the adjustment. Chairs which are fitted out in this way allow sitting postures from a forwardly inclined position (writing position), via a central position (basic position), to a rearwardly inclined position (relaxing position). Chairs of this type provide increased comfort for the user since the backrest and posterior support are advantageously adapted in ergonomic terms to the sitting posture assumed in each case.
PRIOR ART
The principle of subdividing the seat surface into a fixed thigh support and a pivotable posterior support, which passes into the backrest, is known from CH-A-568 738. The subdivision is realized using hinge elements which are arranged in the side parts of the supporting frame.
A chair of the relevant type is disclosed in CH-A-582 498. However, this design is likewise restricted to the pivotability of the backrest, which is connected to the posterior support, it being additionally proposed here for the covering of the seat surface to be continued, beyond the pivot axis, as far as the rear part of the frame. A pneumatic spring is indeed used for the inclination adjustment, but no provision is made for the possibility of height adjustment, an integrated, complete adjusting mechanism and a frame structure and padded covering which satisfy current production requirements and esthetic considerations.
OBJECT OF THE INVENTION
The object of the invention, for a chair with a pivot axis running over the seat surface, is thus to provide an improved frame structure and a combined adjusting mechanism which makes all modern functions possible. In terms of its basic structure, the chair mechanism is intended to be as straightforward as possible, functionally reliable, low maintenance and convenient to operate. Furthermore, the adjusting mechanism which is to be proposed is to be concealed, as a compact structure, in the chair. In the development, the padded covering in functional interaction with the frame structure has particular significance, i.e. it results in rational and cost-effective production and fitting in series manufacturing while at the same time fulfilling current, creative esthetic requirements.
SUMMARY OF THE INVENTION
The seat support of the chair frame is positioned on the conical tip of a pneumatic spring which is arranged vertically and centrally in an underframe which is known per se, the pneumatic spring being provided for the height adjustment and being referred to her
REFERENCES:
patent: 4408800 (1983-10-01), Knapp
patent: 4521053 (1985-06-01), De Boer
patent: 4589697 (1986-05-01), Bauer et al.
patent: 5069496 (1991-12-01), Kunh et al.
patent: 5577804 (1996-11-01), Tedesco
patent: 5725276 (1998-03-01), Ginat
Jr. Milton Nelson
Vitra Patents AG
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