Chairs and seats – Movable bottom – Tiltable
Patent
1985-04-03
1986-12-09
Aschenbrenner, Peter A.
Chairs and seats
Movable bottom
Tiltable
297300, A47C 300
Patent
active
046276629
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATION(S)
This United States application stems from PCT International Application No.PCT/GB84/00272 filed Aug. 8, 1984.
This invention relates to an improved tilting mechanism for a chair of the kind disclosed in our P.C.T. Application Number PCT/GB82/00307 (Early published No. WO 83/01562).
In said PCT application the chair has a seat portion to the underside of which is secured a frame part having a socket member into which the top of a conventional support post of the chair is fitted. To the seat portion, a backrest part is pivotally connected so that by pivotting the backrest relative to the seat portion the angle between the backrest and seat portion can be varied. A mechanism is described for allowing said required degree of tilt and for locking the backrest in the desired position relative to the seat portion.
However in recent times doctors have expressed the opinion that an arrangement where the backrest is tiltable to a fixed seat portion could be disadvantageous because of the fixed position of the seat portion irrespective of the angle of the backrest. If with the seat portion horizontal, a person sitting on the chair leans forward, the person's stomach muscles become compressed and the muscles at the rear of the thighs become stretched. However if the seat portion of the chair could tilt to accommodate the person's action in leaning forward, such harmful muscle compression and stretching could be avoided.
An object of the invention is thus to provide a tilting mechanism for a chair, which, in use, allows the seat portion to tilt.
According to the invention there is provided a tilting mechanism for a chair comprising a first part for connection, in use, to a seat portion of the chair, a second part, for connection, in use, to a backrest portion of the chair, and a third part for connection, in use, to a base of the chair, said first and second parts being pivotally connected together for relative pivotal movement about a horizontal axis, in use, said first and third parts being pivotally connected together by a horizontal axis so that said first part can move pivotally, in use, about said third part, and there being means for adjusting the relative angular positions of the first and second parts, and the first and third parts, and for releasably locking them in said chosen relative angular positions.
The invention will not be described, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is a schematic underneath view of part of a tilting mechanism of the invention,
FIG. 2 is a schematic, fragmentary view with one side of the mechanism removed,
FIG. 3 is a front view of a key plate which is disposed at one side of the mechanism for controlling a manually operable lever for adjusting the tilt of the chair seat and/or the backrest,
FIG. 4 is a section through the key plate of FIG. 3,
FIG. 5 is a front view of an index plate which is disposed at the other side of the mechanism also for controlling said lever,
FIG. 6 is a section through the index plate of FIG. 5,
FIG. 7 is a fragmentary view of one side of the mechanism,
FIG. 8 is a view of the manually operable tilt adjusting lever, together with the key plate, a spring cup, a compression spring, a cam and an index pin for controlling said adjustment,
FIGS. 9A to 9C are opposite end views and a longitudinal sectional view of the cam of FIG. 8, and
FIGS. 10A to 10C show alternative positions of the cam as the tilt adjusting lever is operated.
The type of chair to which the mechanism of the present invention is usually applied is that conventionally referred to as a typists' chair. Such a chair is illustrated in FIG. 1 of our PCT application referred to in the introduction to the specification. As shown therein the chair has a base comprising a multiplicity of castor-supporting legs extending radially outwardly from the bottom of an upright cylindrical support column. At the top of the column there is a conventional gas-spring height adjustment means for raising or lowering a seat of the
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Bailey Malcolm J.
Carter David E.
Willatts Brian A.
Aschenbrenner Peter A.
Pledge Office Chairs Limited
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