Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to seats, and
particularly to a tilting seat.
It is estimated that between 65 and 75~ of days
lost from work is due to back ailmen-ts. More and more,
particularly wi-th the development of compu-ters, the worker
is required to spend a greater amount of -time si-tting at a
work station. On -the other hand, most conventional chairs
or seating arrangements presently u-tilized in the workplace
require the us~r to hunch forward in order to work at a
desk or table. By hunching forward, the stress on the
lumbar region ir, increased by 300~, resulting in premature
disin-tegration of the lower discs and vertebral arthritic
degeneration.
In recent years, a myriad of "ergonomically"
designed chairs have been developed, all of which use a
backward inclined seat. Although these chairs have proved
to be more "comfortable" in -the reclined position, the user
is s-till obliged -to hunch forward in order to work at a
desk or table. By hunching forward, the stress on the
lower spine (lumbar region) is increased some 300~; the
result being a premature disintegration of the lower discs
and vertebral arthritic degeneration.
Recent research has brought about a greater com-
prehension of the function of the lumbar spine and brings
into question the basic traditional seated work position.
sased on the sound physiological evidence as provided by
internationally recognized experts such as Doctors Keegan,
Nachemson, and Grandjean, the ideal seated work posture
should maintain a minimum curve in the lower spine
~lordosis). This position allows the efficient support of
body weight, with the least amount of work and s-tress. In
most cases, a person using a backward inclined seat,
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eradicates the lordosis by leaning forward to work. The
forward inclined seat compensates for this necessary move-
ment towards the work surface by allowiny the person to
tilt his whole body forward, thus elimina-ting -the rounding
of the back and the subsequen-t loss of the lordotic curve.
The forward incline makes it possible for a person -to
maintain this critical lordosis of the lumbar spine while
performing many different tasks.
Recent research has brought about a greater
unders-tanding of -the s-truc-ture and function of the lumbar
spine and brings into ~uestion the basic traditional seat-
ing and the position of the user. According to physiologi-
cal evidence, the ideal seated work pos-ture should maintain
a minimum lordotic curve in the lower spine. This position
allows the efficient support of the body weight with the
least amoun-t of stress.
It is an aim of the present invention to provide
a seat which would be comfortable in a res-t position, that
is, in a normal sitting position, and which would tilt for-
ward with the user as the user advances himself to the worktable, thereby generally maintaining an upright back posi-
tion with a slight lordotic curve of -the lumbar region.
It is also an aim of the present invention to
provide a seat which will be inclined forwardly when the
seat is advanced or tilted towards a work position and
allows the user to tilt his or her body forward, -thus
eliminating the hunching of the back and the subsequent
loss of lordosis in the lumbar spine.
A construction in accordance with the present
invention comprises a seat having a base, a stem pivotally
mounted on the base and tiltable relative to the base about
a pivot axis at the base, a buttocks support mounted on the
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front of the stem, the stem extending rearwardly at an
acute angle from a vertical plane containing the pivot axis
and adapted to pivot from a rest position to a forward
positlon where the s-tem is subs-tantially near rearward of
the vertical plane, the cen-ter of -the bu-t-tocks support
being substantially near the vertical plane in the rest
position and forward of the vertical plane in -the forward
position, and means on the base limiting the pivoting arc
of travel of the stem between the rest posi-tion and the
forward posi-tion.
In a more specific construction of the present
invention, the buttocks support is mounted -to -the fron-t of
the stem for llmi-ted pivotal movement relative to -the stem
about an axis parallel to -the tilting axis.
It has been found tha-t in a preferred embodiment
the stem in its rest posi-tion would be supported at an
angle of 21 from the vertical plane and at an angle of 9
from the vertical plane in its forward position such that
the total pivotal arc of travel of the s-tem is 12.
Thus, this construction allows the user to sit
back on the seat or chair when not working over a work desk
or table. However, when the user moves forward to work
over the table, the buttocks support and the stem would
merely follow the user and tilt forward allowing the user
to maintain a proper erect position with the proper
lordotic curve in the lumbar region. It is believed that
this would allow the user to work in a much more comfort-
able position with considerably less, stress on his back.
; The phenomenon is similar to the natural inclination,
particularly with youngsters, to sit on the edge of their
chair while working over a table. It has also been found,
in studies, that it is important to maintain a relatively
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open or obtuse angle between the -thighs and -the upper body.
With the embodiments described herein, thls ob-tuse angle
can be main-tained between the thighs and the upper body
even when the user is working over his work -table due to
the tilting ancl inclination of the bu-t-tocks suppor-t on the
seat. Using an ordinary chair, even if moving the chair
forward under the table while working over the table, the
thighs assume a closed or acute angle with respect to the
upper body when the user is hunched over the table.
~laving thus generally descrlbed the na-ture of -the
inven-tion, re~erence will now be made to the accompanying
drawings, showing by way of illustration, a preferred
embodiment thereof, and in which:
Figure 1 is a perspective view of one embodiment
of the seat in accordance with the
present invention;
Figure 2 is a side elevation of the seat shown in
Figure l;
Figure 3 is a fron-t eleva-tion of a seat showing
another embodiment of -the present inven-
tion;
Figure 4 is a vertical cross-section taken along
line 4-4 in Figure 3;
Figure 5 is a fragmentary enlarged cross-section
taken along line 5-5 in Figure l;
Figure 6 is an enlarged fragmentary cross-section
taken along line 6-6 of Figure 3;
Figure 7 is a fragmentary top plan view of a
detail of the present invention;
Figure 8 is a schematic view showing the
different positions of the seat;
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Figure 9 is a front elevation of the base in
accordance with an embodimen-t of the
present inven-tion;
Figure 10 is a side elevation of the base shown
in Figure 9;
Figure 11 is a vertical cross-section taken
through a detail similar to that shown
in Figure S, of another differen-t
embodiment thereof;
Figure 12 is a fragmentary enlarged cross-section
of a detail similar -to tha-t shown in
Figure 5 but of a different embodiment
thereof;
Figure 13 is an enlarged fragmentary sectional
view along line 13-13 of Figure 12;
Figure 14 is a bottom plan view of the base shown
in Figure 9;
Figure 15 is a cross-sec-tional view taken along
line 15-15 of Figure 14; and
Figure 16 is a cross-sectional view, sim~lar to
Figure 15, bu-t showing a detail thereof
in a different operative posi-tion.
Referring now to the drawings, there is shown in
Figures 1 and 2, a first embodiment of a seat 10 including
a base 12, a stem 14, and a buttocks support 16.
The base 12 and stem 14 in this embodiment are
integral, and as s:hown in Figure 2, the base 12 describes
an acute angle with the stem 14 extending over -the base 12
at an angle of 71. The buttocks support 16 is made of
rnolded plastics material and may have a shell 18 and a soft
interior 20. The buttocks support 16 is pivotally mounted
at 22 on a bracket 24 which can be adjustably located along
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the longitudinal axis of -the stem 14.
The stem 14 is in the form of an elonga-ted member
having a track 26 in the form of an elongated slo-t having a
T-shaped cross-section. As shown in Figure 5, -the bracket
24 lncludes a carr:iage 28 sliding in the track 26. The
carriage 28 i.s provided with a series of spaced-apart
apertures 30 wi-th each aperture having a radial flange 32.
The back of the stem 14 is provided with a bore 34.
A locking pin 36, including a rounded knob 38 and
an L-shaped pin 40, passes through the bore 34. The lock-
ing pin 36 also includes a spring 42 in the recessed part
of -the bore 34. The L-shaped pin 40 is adapted to engage
in apertures 30 of the carriage 28 to lock the carriage in
a selected position.
When it is required to release -the carriage 28
from a given position, the carriage must be moved upwardly
slightly to disengage the L-shaped pin 40 from -the flange
32. The~ pin 40 is then retracted agains-t the spring 42
into the recessed portion 34, and -the carri.age 28 is then
free to move t:o a new adjusted vertical position. The
spring 42 will be effective to move the locking pin 40 to a
new aperture 30 on the carriage 28 when such aperture is
aligned therewith.
As also seen in Figure 5, the seat 16 is pivotally
mounted on the pivot shaft 22 in the bracket 24, and the
; pivoting movement of the seat is restricted by a limit pin
44 which is fixed to the seat 16 and travels in an arcuate
slot 46.
The stem 14 merges with the base 12 forming an
acute angle with reference to the embodiment in Figures 1
and 2, and the angled surface 48 formed at the forward part
: of the base 12 is rounded, allowing the seat t;o he pivoted
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or tilted along the rounded surface 48 which defines a
tilting axis of the seat 10.
As shown in Figures 1 and 2, the seat 10 is illus-
trated in a res-t position. A user may sit on the seat in
this position and be comfortably erec-t. If the user wishes
to move forwardly to a work position within -the arc between
the position shown in full lines and that shown in do-tted
lines in Figure 2, he need merely move himself forward
(i.e., over a table), and -the seat 10 will -tilt forward
:L0 with him. In the case of -the embodimen-t shown in Figures 1
and 2, the seat will tilt about the axis defined by the
surface 48, moving the center of gravity of -the user from
a position over or behind the vertical plane containing the
axis of tilting to a position shown in dot-ted lines in
Figure 2 where the buttocks support 16 is well ahead of -the
vertical plane so defined. The user's forward movemen-t
also brings the center of gravity thereof beyond the verti-
cal plane including the tilting axis, and the natural
inclination to maintain an open obtuse angle f of the
-thighs -to the upper body will cause the buttocks support 16
to pivot abou-t the shaft 22 through a possible angle d of
45. The angle f may vary from 130 in the rest position
to 105 in the forward position. Thus, as seen in Figure
8, when the seat is tilted forwardly, the lordotic curve in
the lumbar region of the spine is maintained.
The tilt:ing of the seat will normally be through
an arc a in the drawings which may be in the area of 20,
although -this arc may vary 5 either way.
It is also seen that if the user were to lean
back from the table, the seat 10 will, because of its stable
position, tilt back to a rest position as shown in Figures
1 and 2 in full lines.
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.
Another embodiment of the seat is shown in
Figures 3, 4 and 6, in which -the base 50 is in the form of
a turntable, including a sub-base 51. The sub-base 51 may
have a rubber or soft plas-tic molded coverlng 52 over -the
edge of a skirt 54 extending from an annulus 56 which is in
a horizontal plane. A lower bearing race 58 is mounted to
the annulus 56 and supports ball bearings 60 as shown in
Figure 6. An upper base portion 62 is provided which mounts
an upper race 64 which cooperates with -the lower race 58
and the ball bearings 60. The upper base portion 62 has an
overhanging skirt 66. The upper base por-tion 62 moun-ts a
pair of ups-tanding journals 68 and 70 which receive an
arcuate lower member 72 of the stem 74. The journals have
a rearward stop 76 and a forward stop 78 which limit -the
pivoting or tilting movement of the stem 74 relative to the
base. The arc may be limited to 20. The arc, iden-tified
by -the letter c, is actually 12 with the forward position
at 9 from the vertical plane through the pivo-t axis and
the rest posit::ion at 21 from the vertical plane.
In -t:he preferred embodiment, the stem 14 does not
pass the vertical plane -through the pivot axis of the stem,
but rather its movement terminates in a forward position
slightly behind the vertical plane. As can be seen, however,
the buttocks support 16 in the rest position has its center
position in the vertical plane or just slightly behind the
vertical plane, while in the forward position, the buttocks
support 16 is in front of the vertical plane. The user of
the seat as described supports its i.ull weigh-t on the seat
both in the rest position and the forward position, as shown
in Figure 8 of the drawings.
Thus, in the embodiment shown in Figures 3 ~nd 4,
the user has the advantage of the tilting seat previously
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described and may rota-te -the seat on the -turntable.
Figures 7 and 8 represen-t the eEfec-t on -the body
and in particular as represen-ted by a skeleton diagram in
these drawings. The bu-ttocks suppor-t 16 is provided wi-th
an enlarged mound 80 forward and central of -the support
which influences the thigh bones to ro-tate outwardly in the
direction of the arrows shown in Figure 7, -to provide a
more natural and comfortable seating. Figure 8 represents
the position of the lumbar region of -the spine in both the
rest position and the tilting position of -the seat 10.
A different embodiment of -the base is illus-
trated in Figures 9, 10, and 14 through 16. The base 110
includes a turntable por-tion 112 and an upstanding pedestal
114. As shown in Figure 10, the pedestal 114 includes a
slot defined by a pair of abutments 116 and 118 which limit
the pivoting arc of travel of the stem 14. The s-tem 14
includes two ears 120 which are ~ournaled on a pivot shaft
122. The abutment surface 116 is provided with a bellows
type resilient device 124 while the abutmen-t 118 is pro-
vided with a resilient stop 126. The base, as best shownin Figures 14 through 16, includes a sub-frame 128 mounted
by means of a rubber or plastic suspension device 130 to
the shell 132. The shell 132 includes a skirt 134 surroun-
ding the periphery of the sub-frame 128. The sub-frame 128
is provided with a series of openings 136. A leg 138 is
integrally molded at 140 to the sub-frame 128 or may be
otherwise fixed thereto. The other end of the leg 138
includes a head 1~2 defining a spherical socket mounting a
ball 144. The legs 138 are chosen of a material and size
such that when there is no weight on the seat, the balls
144 are in contact with the ground or floor, but as soon as
a weight is applied to the seat, the legs 138 will flex to
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allow the sub-frame 128 to rest on the floor and thereby
prevent the rolling movement of the base.
Referring now to Figures 12 and 13, there is
shown a stem 14 having a carriage 150 sliding in -the track
152. The carriage 150, which is similar to carriage 28,
mounts a bracket 154. A pivot shaft 156 is fixed to the
bracket 15~, and a pair of downwardly extending ears 158
are pivotally mounted to -the shaft 156. The ears 158 mount
the shell 160 of the buttocks support. A small resilien-t
pad 162 :is provided on the upper surface of -the bracket 154
to act as a stop for the rearward pivoting movement of the
buttocks support 16.
Figure 11 illus-tra-tes another embodiment of the
locking pin 36. The embodimen-t in Figure 11 has reference
numeral~; raised by 200 which correspond with the numerals
in Figure 5. The carriage 228 in this embodiment is made
in the i.orm of a U-shaped channel with apertures 230 pro-
vided Oll one side thereof. The carriage 228 slides in -the
track 226. The locking pin 236 includes an L-shaped pin
240 moving in a sleeve 241 against the spring 242. A pin
244 acts as a forward limit for the pin 240. The ball or
knob 238 is retained on the pin 240 by means of a ball
retainer nut 246 fixed to the pin 240. The sleeve 241
includes flanges 243 on the interior of the track 226, as
illustrated. The operation of the locking pin 236 is the
same as the locking pin 36.
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