Chairs and seats – Movable back
Patent
1999-03-02
2000-12-05
Nelson, Jr., Milton
Chairs and seats
Movable back
B60N 202
Patent
active
061556432
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a device for adjusting the height of the backrest of a seat back portion, in particular in office chairs.
BACKGROUND OF THE INVENTION
Office chairs are known comprising a spoke-type base with feet or wheels, a column mounted on said base and provided with a gas piston for adjusting the height of the sitting plane from the floor, and a seating portion which can be separate from a seat back portion or joined to it and supported by said column.
Generally the seat back portion consists of a pair of tubes which engage telescopically, one tube being rigid with the seating portion and the other tube being provided with a padded back-rest.
A known type of height adjustment device for the back-rest consists of a locking pin rigid with one of the tubes and slidable within a slotted hole provided in the other tube.
In another known device consists of a pin engagable in a hole provided in one tube and engagable elastically in a plurality of superposed holes provided in the other tube.
To another known type of adjustment device, one of the telescopic tubes comprises a plurality of notches in which a rigid tooth element elastically engages.
These known devices have however certain drawbacks, and in particular: in a substantial space requirement during transport,
DESCRIPTION OF THE PRIOR ART
GB-A-2.246.287 discloses a guide element rigid with the support plate of a seating portion, a slide for supporting the back rest and engageable with the guide element and slidable along it, and means rigid with the slide which are engageable elastically and selectively in a toothed portion provided on the guide element.
EP-A-0 210 584 discloses an adjusting mechanism for the step-wise height adjustment of the backrest of a workchair comprising two U-form guide bars embracing side edges of a rectangular support extending up from the seat of a chair.
SUMMARY OF THE INVENTION
An object of the invention is to provide a height adjustment device for the back-rest of a seat back portion, which can be easily and comfortably operated.
A further object of the invention is to provide a device having only a small number of components.
A further object of the invention is to provide a device enabling fine adjustment to be effected.
All these and further objects which will be apparent from the ensuing description are attained according to the invention by a device for adjusting the height of the back-rest of a seat back portion, in particular in office chairs, comprising: guide element and slidable along it, to ensure the stability of the position of said slide relative to said guide, flanks of teeth of a toothed portion during the raising of said back rest, and are locked by the active flanks after each passage over a tooth, and in that said elastic means, following their elastic reaction and for a predetermined position of said slide relative to said guide element, are disengagable from said teeth to hence enable said slide to slide by gravity relative to said guide element.
BRIEF DESCRIPTION OF THE DRAWINGS
A preferred embodiment of the present invention and a modification thereof are described in detail hereinafter, with reference to the accompanying drawings, on which:
FIG. 1 is a transparent section through the back-rest height adjustment device,
FIG. 2 is a longitudinal section therethrough on the line II--II of FIG. 1,
FIG. 3 is a cross-section therethrough on the line III--III of FIG. 1,
FIGS. 4-8 are views thereof during adjustment,
FIG. 9 is a schematic side view of a chair provided with the device according to the invention, and
FIG. 10 shows a different embodiment of the device.
DESCRIPTION OF PREFERRED EMBODIMENTS
As can be seen from the figures, the device of the invention is applied to a traditional office chair 1 comprising a spoke-type base 2 with feet 3 or wheels, on column 4 mounted on said base and a support plate 5 for the seating portion 6 and for the support slide 7 for the back-rest 8.
The support slide 7 for the back-rest 8 is formed from a first substantial
REFERENCES:
patent: 4639039 (1987-01-01), Donovan
patent: 5649741 (1997-07-01), Beggs
patent: 5685609 (1997-11-01), Miotto
patent: 5695249 (1997-12-01), Lotfi
Gorgi Claudio
Scagnellato Paolo
Imarc S.p.A.
Jr. Milton Nelson
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