Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
BACXGROUND O~ THE INVE~ITION
This invention relates to chairs having
significa~tly greater comfort than conventional chairs in a
wide variety of sitting postures assumed by the user, yet
providing these functional features by way of unique and less
costly structures. More particularly, the invention concerns
chairs having a seat which is movable back and forth and a
back which is mounted so that it pivots, independently of
the movement of the seat, between upright and inclined
positions,
A substantial improvement in the comfort of chairs
over chairs with fixed geometry may be afforded by the chair
described above insofar as it allows the user to assume various
sitting postures and the chair will conform thereto.
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In chairs in which the seat has little or no
padding, further comfort may be afforded where the seat
supports of the seat supporting structure and the sleeves
are made upwardly concavely arcuate (i.e., curved about a
center of curvature located some distance vertically above
the coincident axes of the respective sleeves and seat
supports) so that the rake of the seat increases, the
farther forward it is on the supports. In chair seats that
are relatively heavily padded, the seat supports and sleeves
need not be curved, inasmuch as the padding will provide
comfortable support to a person sitting in the chair in all
~ositions of forward and backward movement, even though
the shifting of the seat to a more forward position, as
the person leans back to a relaxed position in the chair,
requires the imposition by the seat to the person of a
greater horizontal force component so that the person does
not have the feeling that he will slide off the seat.
Heavy padding provides the necessary change in geometry
that is present when curved sleeves and supports are used
i~ lightly padded or unpadded seats.
The present invention provides an improved or
modified form of the chair described in
Canadian Application Serial No. 241,721 filed December 15, 1975.
The chair of that prior application has either legs or a
pedestal, a frame mounted on the legs or pedestal, and a
seat and a back mounted separately on the frame and is
characterized in that the seat has a pair of spaced-apart
elongated sleeves of uniform internal cross-section extending
lengthwise in parallel vertical planes and is mounted on
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spaced-apart lengthwise forwardly extending cantilevered
seat supports, preferably tubular members, of uniform
external cross-section substantially matching the internal
cross-section of the sleeves. The seat supports receive the
sie_ves in telescoping and slidi~g relation such that the
seat is slidable backward and forward. The back is mounted
on back supports of the chair frame to tilt backward
independently of the position of the seat from a resiliently
restrained relatively upright position to a backward tilted
position.
SUMMARY OF THE INVENTION
The present invention comprises a chair having
either legs or a pedestal, a frame mounted on the legs or
~edestal, and a seat and a back mounted separately on the
frame and is characterized in that the seat has on its under-
side a pair of closely spaced-apart elongated sleeves of
uniform internal cross-section extending lengthwise in
parallel vertical planes and is mounted on a generally
centrally located seat-supporting structure, which seat-
supporting structure has a lengthwise fonwardly extending
cantilevered portion and closely spaced-apart seat supports
of uniform external cross-section substantially matching
the internal cross-section of the sleeves, the sleeves of
the seat being received in telescoping and sliding relation
on the seat supports of the seat supporting structure such
that the seat is slidable backward and fonYard, and in that
the back is mounted on a generally centrally located back
support of the chair frame to tilt backward independently of
the position of the seat from a resiliently restrained
relatively upright position to a backward tilted position.
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Other features and advantages of the present
invention will be readily apparent from the following
detailed description of a preferred embodiment thereof
taken in conjunction with the accompanying drawings.
DESCRIPTION OF THE DRAWINGS
Figs. 1 and 2 are side elevational and front
elevational views of a chair according to the present
invention;
Fig. 3 is a side cross-sectional view of the
seat supporting structure of the chair of Figs. 1 and 2;
Fig. 4 is a top cross-sectional view of the
seat supporting structure taken generally along the lines
23-23 of Fig. 3 and in the direction of the arrows;
Figs.5 to 9 are cross-sectional views taken at
the locations indicated by the lines 24-24, 25-25, 26-26, 27-27
; and 28-28, respectively, of Fig. 3 and in the direction of
the arrows;
Fig. 10 is a side cross-sectional view of the
back of the chair of Figs. 1 and 2 taken generally along
the lines 29-29 of Fig. 2 and in the direction of the
arrows; and
Fig. 11 is a fragmentary, cross-sectional view
of the back mounting structure taken along the lines 30-30
of Fig. 10 and in the direction of the arrows.
DETAILED DESCRIPTION
In the illustrated embodiment of the invention,
a chair, as shown in Figs. 1 to 11, has a five-legged
pedestal base 400 that supports at the height of a chair
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seat a generally "L"-shaped (as viewed from the side) frame
assembly 402. The frame assembly in~ludes a tubular piece 404
of generally rectangular cross-section bent to provide a
ge~erally vertical leg 406 that supports the back 408 of
the chair and a generally horizontal leg 4io that receives
telescopically a tongue 412 (Figs. 3 and 4) that extends
rearwardly from a seat supporting structure 414.
Referring to Figs. 3 to 9, the seat supporting
structure 414 comprises a main body portion 416 that extends '~
lengthwise of the chair and has a dependent boss 418 that
receives the post 420 of the pedestal base 400 (Figs. 3 and 6).
The seat supporting structure 414 has extending longitudinally
along each side and projecting outwardly a pair of laterally
spaced-apart flanges forming seat supports 422, each of
which receives an elongated, generally cup-shaped anti-friction
bearing element 424, for example, an element made of "Teflon"
or nylon. The seat supports 422 are received in telescoping
relation within a pair of laterally spaced-apart sleeves 426
that extend lengthwise under the chair seat 428, the sleeves
being defined by a mounting unit 43Q which is fastened, such
as by screws 432 ~Fig. 9), to bosses 434 molded on the under-
side of the seat 428. The mounting unit 430 is assembled,
such as by rivets 436 (Fig. 8), from a plate 438 which abuts
the underside of the seat 428 and a pair of elongated members
440 of genPrally "Zn-shaped cross-section. The sleeves 426
defined by the plate 438 and the members 440 receive telescopicall
the seat supports 4~2 with a clearance adequate to permit the
seat to slide relatively freely backward and forward on the
seat supports.
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The seat 428 is spring-loaded toward the
rearwardmost position (the position shown in Figs. 3 to 9J
by a coil spring 442 connected under tension between a pin 444
that extends up into a cavity 446 formed in the body portion
416 of the seat supporting structure 414 and a pin 448 that
projects down into the cavity 446 from the plate 438 of the
mounting unit 430. The limit position of backward movement
of the seat 428 is established by engagement of a rubber bumper
450 that is mounted on a rib 452 extending down into the cavity ~,
446 with a pair of ribs 454 on the body portion 416 of the seat
supporting structure that project into the cavity 446. The
forward limit position is established by engagement of the
rubber bumper 450 with the front wall 456 of the body portion 416.
As best shown in Figs. 10 and 11, the back 408 of
the chair of Figs. 1 to 11 is mounted on an extension 458 of the
back support portion 404 by means of a coupling 460 that is
received telescopically in the back support portion 404 with a
clearance that permitsit to be slided up and down to adjust the
height of the back 408. The back is locked at the desired
height by a lock screw 462.
The extension 458 is received in a sleeve 464
molded into the back wall of the chair back 408, and the back
408 is mounted to tilt between the relatively upright position
shown in Fig. 10 and an inclined position (not shown) by a
pivot coupling that is provided by an axle 466 that extends
through holes in the extension 458 and in the sleeve 464.
The back is spring-loaded into the relatively upright position
by a torsion spring 468 of generally the mousetrap type. The
'` forward or upright limit position of tilting of the back 408 is
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established by engagement between the upper part of the back
face of the extension 458 and the inside face of the back
wall of the sleeve 464 in the region marked by the numeral
470 and by engageme~t between the upper end of the front
face of the extension 458 and the part of the back face of
th~ chair back 408 adjacent thereto. The rearward or inclined
limit position of the tilting of the back 408 is established
by engagement of the part of the back of the chair within the
sleeve 464 with the upper edges 472 of the side walls of the
extension 458, which are cut at an angle to provide the
desired limit of tilting of the back. The lower end of the
back wall of the sleeve 464 angles away from the extension
458 to accommodate rearward tilting of the back and may
engage the back wall of the extension 458, further to assist
in supporting the back at the limit of inclined tilting.
The chair described above and shown in the drawings
operates on the principle of independent forward and backward
- movement of the seat and tilting of the back such that the
chair will automatically adopt a configuration that will
provide excellent anatomical support to a person sitting in
the chair. The chair provides optimal distribution of body
weight and excellent sacro-lumbar support in all configurations.
When a person sitting in the chair sits upright, the seat will
be in the rearward position and the back in an upright position.
When the person wants to lean back into a relaxed position in
the chair, the seat will slide forward and the back will
incline, such adjustments in the configuration of the chair
being substantially solely responsive to the sitting posture
of the individual. Except in those cases when the seat is
heavily padded, the increased rake of the seat play an important
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role in supporting the body properly when the person
relaxes back in the chair.
The above-described embodiment of the invention
is intended to be merely exemplary and numerous variations
and modifications may be made without departing from the
spirit and scope of the invention. All such variations and
mcd~fications are intended to be included within the scope
of the invention as defined in the appended claims.
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