Note: Descriptions are shown in the official language in which they were submitted.
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Docket No. LAPD-201/CAN
PROGRESSIVELY CURVED LUMBAR SUPPORT
FOR THE BACK OF A CHAIR
BACKGROUND OF THE INVENTION
[00011 1. Technical Field
This invention relates to a lumbar support located inside the back of a chair
of the kind
which rocks back and forth, such as that commonly found in an office or home
so that a user
can be seated close to a work surface (e.g., a desk or a table). The lumbar
support is adapted to
progressively change its shape from an arced, convex configuration to a
substantially flat
configuration in response to a pressure applied to the chair back so as to
provide support and
maintain a proper posture of the user's back when the chair back stands
upright and the user's
back is erect and close to the work surface and when the chair back rocks
backwards and the
user reclines away from the work surface.
[0002] 2. Background Art
A wide variety of chairs have been used in an office or at home to enable a
user to be
seated adjacent a work surface. In this case, the user can access a computer,
a book, a writing
pad, etc. which lays upon the work surface so that the user can work while
seated. Some chairs
are adapted to rock back and forth in response to the user shifting his weight
backwards and
forwards. With the chair rocked forwards, the user's back is located close to
the work surface
during which work can be accomplished. When the chair rocks backwards, the
user's back is
correspondingly reclined and tilted away from the work surface to enable the
user to relax.
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[0003] A common problem with such conventional office and home chairs occurs
when the
chair rocks forward and the user tries to hold his back erect and close to the
work surface. In
particular, even when the back of the chair stands upright, the back of the
user is usually spaced
forwardly from the chair back. Therefore, the chair back offers little or no
support for the user's
lower back throughout those times when the user is working. Consequently, the
user's back
posture may suffer and, especially during long periods of work, the user may
experience lower
back pain and discomfort. What is even more, when the chair rocks back, the
back of the chair
typically retains its initial shape and is therefore unable to adjust for an
increased compressive
force generated by the user leaning against the chair back.
[0004] What would be desirable is a chair which overcomes these problems to
enable the user's
back to be adequately supported by the chair back so that a proper posture is
maintained and
comfort is enhanced when the chair rocks forward and back. Reference may be
made to my
published U.S. Patent Application No. US 2015/0102647 filed October 10, 2013
for an
example of a dynamic lumbar support located in the back of a chair to improve
posture and
comfort.
SUMMARY OF THE INVENTION
[0005] In general terms, a progressively curved lumbar support is disclosed to
be located inside
the back of a chair that has particular application for use in an office or a
home so that a user
can be seated adjacent a work surface (e.g., a desk or a table) with his back
erect. The chair is
of the kind that rocks back and forth when the user shifts his weight
backwards and forwards.
The progressively curved lumbar support herein disclosed is responsive to a
pressure applied
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Date Recue/Date Received 2022-03-10
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by the user against the chair back. That is, the lumbar support is adapted to
continuously
change its shape from an arced, convex configuration to a substantially flat
configuration as the
user shifts his weight against the chair back. By virtue of the foregoing, the
user's lower back
will be supported and a proper posture maintained when the chair rocks forward
and the back
of the chair stands upright and when the chair rocks back and the chair back
tilts away from the
work surface.
100061 The progressively curved lumbar support within the back of the chair
includes a rigid
(e.g., plywood) backing and a resilient (e.g., foam) cushion back support that
is located in front
of and spaced from the backing. The cushion back support has an initially
arced, protruding
configuration. A flexible posture-maintaining sheet is positioned against the
cushion back
support to urge the protruding back support towards the lower back of the
user. A pair of
inclined guide blocks having ramped surfaces are attached to the backing. A
tension strap runs
vertically through the chair back within the space between the backing and the
cushion back
support. One end of the tension strap is connected to a tilt pressure-
responsive rod which runs
horizontally across the chair back for receipt by the pair of inclined guide
blocks.
100071 As the user leans back and the chair rocks backwards, a compressive
force is applied by
the user's back against the cushion back support, whereby the flexible posture-
maintaining
sheet is flexed. At the same time, the tension strap bends back and the
horizontally extending
tilt pressure-responsive rod connected thereto is simultaneously pushed along
the cushion back
support and down the ramped surfaces of the pair of inclined guide blocks. The
movement of
the tilt pressure-responsive rod over the inclined guide blocks in response to
the pressure
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generated by the user's back controls the curvature of the cushion back
support. More
particularly, the initially arced, convex cushion back support will be
progressively and
continuously flattened as the tilt pressure-responsive rod rides down the
guide blocks and along
the back support. When the compressive force is terminated and the chair rocks
forwards, the
tension strap recovers, and the tilt pressure-responsive rod is
correspondingly pulled up the
ramped surfaces of the inclined guide blocks. Accordingly, the previously
flattened cushion
back support returns to its initial arced, convex configuration to once again
protrude towards
and support the lower back of the user.
[0008] The respective tops of the rigid backing and the cushion back support
of the
progressively curved lumbar support inside the chair back are pivotally
connected to one
another by means of hinges. By virtue of the foregoing, the back support is
rotatable relative to
the backing during manufacture of the chair from a folded closed position
lying opposite the
backing to an unfolded open position standing upwardly from the backing. The
hinges also
permit the cushion back support to pivot and shift relative to the backing
when the tilt pressure-
responsive rod is being pushed and pulled over the pair of inclined guide
blocks.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a side view of a chair having a progressively curved lumbar
support according
to a preferred embodiment located inside the chair back and including a
cushion back support
having an initial arced, convex shape when a user leans forward and sits erect
in the chair
adjacent a work surface;
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[0010] FIG. 2 is a side view of the chair of FIG. 1 with the cushion back
support of the
progressively curved lumbar support being compressed and flattened when the
user leans back
in the chair and reclines away from the work surface;
[0011] FIG. 3 is a perspective view of the chair of FIGs. 1 and 2 showing the
progressively
curved lumbar back support inside the chair back between a rigid backing
thereof and the
cushion back support;
[0012] FIG. 4 shows the cushion back support rotated at a set of hinges to an
open unfolded
condition standing upwardly from the backing to permit access to the
progressively curved
lumbar support during manufacture and assembly of the chair; and
[0013] FIG. 5 is an enlarged detail of the progressively curved lumbar support
shown in FIG.
4; and
[0014] FIGs. 6 and 7 shows the cushion back support of the progressively
curved lumbar
support rotated to the open unfolded condition at a different set of hinges by
which the cushion
back support is pivotally coupled to the backing inside the chair back.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0015] Referring concurrently to FIGs. 1-5 of the drawings, a progressively
curved lumbar
support 1 is shown and disclosed for use at the back of a chair 3. The chair 3
is preferably one
that rocks back and forth and is of the kind that would commonly be found in
an office or at
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home to provide a seat for one working at a desk, a table or a similar work
surface. However,
the specific use of the chair 3 is not to be regarded as a limitation of this
invention.
[0016] Like a typical chair, the chair 3 shown in FIGs. 1-5 includes a seat 5
to support the
weight of a user. The chair seat 5 is held above the ground by a base 6 having
a set of
outstretched legs 7 to which respective rollers 9 are attached to permit the
chair 3 to be moved
from place-to-place. A gas cylinder 10 extends between the base 6 and a gas
cylinder receiver
12 that projects downwardly from a seat plate 14. A lever arm (designated 15
in FIGs. 3 and 4)
cooperates with the gas cylinder 10 to enable the elevation of the seat 5 to
be adjusted to suit
the needs of the user. A tension adjustment knob 16 is accessible below the
seat plate 14. The
tension adjustment knob 16 is rotated to adjust the spring tension of the seat
5 depending upon
the size and weight of the user.
[0017] The progressively curved lumbar support 1 is located within the back 20
of the chair 3.
As will soon be explained, and as an important advantage of this invention,
the lumbar support
1 initially has an arced, convex configuration that protrudes against and
supports the user's back
so as to maintain a proper posture and enhance comfort when the chair 3 rocks
forward and the
chair back 20 stands upright to enable the user to sit erect and close to the
work surface (best
shown in FIG. 1). The lumbar support 1 is also adapted to undergo a
progressive change of
shape from the arced, convex configuration (of FIG. 1) to a relatively
flattened configuration as
the user reclines and the chair rocks backwards so that the back 20 of the
chair tilts away from
the work surface (best shown in FIG. 2).
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[00181 The back 20 of the chair 3 within which the progressively curved lumbar
support 1 is
located stands upwardly from the seat 5 . The chair back 20 is surrounded by a
protective
cover or upholstery (not shown). The back 20 includes a cushion back support
22 that lies
inside the back cover and is preferably manufactured from a resilient material
(e.g., foam) to
provide support for the user's back at all times whether the user leans
forward or back in the
chair. The cushion back support 22 initially has the aforementioned convex
configuration
shown in FIG. 1 so as to protrude towards and against the user's back when the
chair back 20
stands upright to enable the user to be seated comfortably and close to the
work surface. The
chair back 20 also includes a rigid (e.g., plywood) backing 24 that lies
inside the back cover.
When the chair 3 is in use, the backing 24 is spaced from and lies opposite
the cushion back
support 22.
[0019] The chair 3 is shown having a pair of arms 26 and 28 (best shown in
FIGs. 3 and 4)
located at opposite sides of the seat 5. The arms 26 and 28 are attached to
the chair back 20 at
opposing brackets 30 and 32 that are affixed to opposite sides of the rigid
backing 24 (best
shown in FIG. 4). However, the arms 26 and 28 may also be connected to the
seat 5 or to each
of the back 20 and the seat 5. An arm rest 34 is attached atop each of the
pair of arms 26 and
28 upon which the arms of the user may be laid.
[00201 Details of the progressively curved lumbar support 1 for the chair 3
are now described
while continuing to refer to FIGs. 1-5 of the drawings. According to a
preferred embodiment of
this invention, the lumbar support 1 includes a posture-maintaining sheet 40
that is attached
(e.g., adhesively bonded) to the underside of (i.e., behind) the cushion back
support 22 within
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the chair back 20. The posture-maintaining sheet 40 is manufactured from a
relatively stiff but
flexible material such as wood, plastic, metal or the like so as to have a
spring memory. The
sheet 40 is positioned against the cushion back support 22 to maintain the
back support in its
initially convex configuration (of FIG. 1) when the user sits erect and the
chair back 20 stands
upright. That is, the posture-maintaining sheet 40 urges the cushion back
support 22 to
protrude towards and into engagement with the user's lower back. The posture-
maintaining
sheet 40 is adapted to flex to enable the convex cushion back support 22 to
progressively
change its shape to the relatively flattened configuration (of FIG. 2) in
response to a
compressive force generated thereagainst when the user reclines and leans back
against the
chair back 20.
[0021] The progressively curved lumbar support 1 also includes a pair of
inclined guide blocks
42 and 44 that are affixed to opposite sides of the rigid backing 24 of the
chair back 20 (best
shown in FIGs. 4 and 5). When the cushion back support 22 is rotated to a soon-
to-be
described folded and closed position as shown in FIGs. 1 and 2 at which to lie
opposite and
cover the backing 24 of the chair back 20, the inclined guide blocks 42 and 44
project from the
backing 22 towards the back support 22. Each of the pair of inclined guide
blocks 42 and 44
includes a flat surface 46 and 48 that ramps downwardly towards the top of the
backing 24. As
is best shown in FIGs. 2 and 5, a stop 49 and 50 is formed at the highest end
(relative to the
backing 24) of each ramped surface 46 and 48 of each of the pair of inclined
guide blocks 42
and 44. The guide blocks 42 and 44 may be manufactured from any wear-resistant
material,
such as wood, plastic or the like.
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[0022] A tension strap 52 runs vertically through the back 20 of the chair 3
within the space
that separates the cushion back support 22 from the backing 24 when the back
support 22 is
rotated to its aforementioned folded and closed position. The top of the
tension strap 52 is
connected to a soon-to-be described tilt pressure-responsive rod 64 by means
of an upper
bracket 54 such that the top of strap 52 is positioned between the pair of
inclined guide blocks
42 and 44. The opposite bottom of the tension strap 52 is connected to a first
end of a
stationary strap support plate 56. The approximate midpoint of the tension
strap 52 is secured
to the backing 24 by means of a lower bracket 58 which holds the tension strap
52 close to
backing 24.
[0023] The first end of the strap support plate 56 which is connected to the
vertical tension
strap 52 runs below the seat plate 14 at the bottom of the chair seat 5. The
opposite end of the
strap support plate 56 is attached to the previously-described gas cylinder
receiver 12 of the
chair 3 which extends downwardly from seat plate 14. By way of example, the
opposite end of
the strap support plate 56 has a coupling ring 60 shown in FlGs. 1 and 2 which
is located in
surrounding engagement with the gas cylinder receiver 12 during the
manufacture or assembly
of the chair 3. The strap support plate 56 is preferably manufactured from a
rigid material such
as steel or the like.
[0024] A tilt pressure-responsive rod 64 is affixed (e.g., welded) across the
top of the vertical
tension strap 52 so as to extend horizontally through the back 20 of the chair
3. The tilt
pressure-responsive rod 64 has a length so that the opposite ends thereof are
received against
respective ones of the ramped surfaces 46 and 48 of the pair of inclined guide
blocks 42 and 44
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(best shown in FIG. 5) so as to be adapted to slide therealong in a manner
that will soon be
explained. A relatively wide end cap 66 is attached to each of the ends of the
tilt pressure-
responsive rod 64 to prevent the rod from sliding off the guide blocks 42 and
44. In this same
regard, rod retention straps 68 and 70 are disposed above the ramped surfaces
46 and 48 of
inclined.guide blocks 42 and 44 to hold the tilt pressure-responsive rod 64
against the guide
blocks 42 and 44. To accomplish the foregoing, a first end of each rod
retention strap 68 and
70 is fastened to the backing 24, and the opposite end of each strap 68 and 70
is fastened to
highest end of the inclined guide blocks 42 and 44. In this manner, the rod
retention straps 68
and 70 will engage the tilt pressure-responsive rod 64 as the rod rides up and
down over guide
blocks 42 and 44 for an advantage that will soon be described.
[0025] An optional friction-reducing sheet 71 is affixed (e.g., adhesively
bonded) to the
underside of (i.e., behind) the posture-maintaining sheet 40 which is attached
to the underside
of the cushion back support 22. The sheet 71, which is manufactured from
plastic, or the like,
has a width that is sized to fit between the pair of inclined guide blocks 42
and 44 when the
cushion back support 22 is rotated to its folded and closed position opposite
the backing 24 of
seat back 20. Thus, the tilt pressure-responsive rod 64 will engage and move
along the optional
friction-reducing sheet 71 (or the posture-maintaining sheet 40) at the same
time that the rod
rides up and down over the inclined guide blocks 42 and 44.
100261 As an important feature of this invention, the curved cushion back
support 22 of the
back 20 of the chair 3 is hingedly connected to the rigid backing 24. In this
manner, the
cushion back support 22 is rotatable relative to backing 24 between its
aforementioned folded
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and closed position lying opposite the backing 24 (best shown in FIGs. 1-3) so
as to cover the
tilt pressure-responsive rod 64 and the pair of guide blocks 42 and 44 when
the chair 3 is in use
at a home or office and an unfolded and open position lying above the backing
(best shown in
FIG. 4) to expose and permit access to rod 64 and guide blocks 42 and 44 to
facilitate the
assembly and repair thereof during manufacture of the chair 3.
100271 To enable the cushion back support 22 to rotate between the folded and
unfolded
positions as just described, and according to one example, the top of each of
the cushion back
support 22 and the rigid backing 24 are pivotally coupled to one another by
means of a pair of
conventional hinges 72. The hinges 72 are connected between backing 24 and the
opposing
flexible sheet 40 carried by back support 22.
[0028] The operation of the progressively curved lumbar support 1 and the
compression of the
cushion back support 22 thereof within the back 20 of the chair 3 for
maximizing the comfort
and enhancing the posture of one sitting in the chair 3 are now described
while continuing to
refer to FIGs. 1-5 of the drawings. In FIG. 1, the user is sitting erect in
the chair 3, the chair
back 20 is tilted forwards and standing upright from the seat 5, and the
cushion back support 22
is rotated downwardly to its folded and closed position lying opposite the
rigid backing 24.
The tension adjustment knob 16 which lies below the seat plate 14 includes a
spring (not
shown) which automatically biases the chair back 20 to the upstanding position
shown in FIG.
1. In this
case, the resilient cushion back support 22 of the lumbar support 1 to which
the
flexible posture-maintaining sheet 40 is bonded is at rest, and little
compressive force is applied
thercagainst by the user's back.
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[0029] In its at-rest condition shown in FIG. 1, the resilient cushion back
support 22 has an
initially arced, convex shape which protrudes forwardly from the chair back 20
towards the
user seated in the chair 3 so as to fit comfortably within and provide support
for the user's lower
back. As previously explained, the posture-maintaining sheet 40 helps to urge
the back support
22 towards and into engagement with the user's back. By virtue of the
foregoing, the arced,
convex cushion back support 22 maintains a proper back posture as the user is
working
adjacent the work surface. At the same time, the tilt pressure-responsive rod
64 that is affixed
to and extends horizontally across the top of the tension strap 52 is held at
the highest end of
the ramped surfaces 46 and 48 of the pair of inclined guide blocks 42 and 44,
and the tension
strap 52 stands vertically and at full tension inside the chair back 20.
[0030] FIG. 2 shows the chair 3 rocked backwards after the user has reclined
and shifted his
weight against the chair back 20, so that the chair back 20 tilts away from
the work surface. In
this case, a compressive force is generated by the user's back against the
chair back 20 to cause
the resilient cushion back support 22 to be compressed. In its compressed
condition as shown
in FIG. 2, the shape of the formerly at-rest cushion back support 22 changes
from being arced
and convex to a shape which is now substantially flattened so as to provide
continuous support
for the user's lower back. The flexible posture-maintaining sheet 40 attached
to the underside
of the cushion back support 22 follows the shape of the user's back so as to
be pushed back and
become slightly bent. That is to say, the compressive force generated by the
user's back
against back support 22 stresses the flexible posture-maintaining sheet 40,
such that the sheet is
now flexed and energy is stored.
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[0031] In FIG. 2, when the user reclines and shifts his weight to generate a
compressive force
against the cushion back support 22 to cause the chair back 20 to tilt
backwards, the vertical
tension strap 52 to which the tilt pressure-responsive rod 52 is affixed is
correspondingly bent
backwards (i.e., in a counterclockwise direction) relative to the stationary
strap support plate 56
below the chair seat 5. At the same time that the cushion back support 22 is
compressed and
the tension strap 52 is bent, the horizontally-extending tilt pressure-
responsive rod 64 at the top
of the rod 64 is pushed backwards so as to ride down the ramped surfaces 46
and 48 of the pair
of inclined guide blocks 42 and 44. It may be appreciated that the tilt
pressure-responsive rod
64 is responsive to the compressive force generated by the user's back against
the chair back 20
and to the backwards tilt of the chair back so that the movement of rod 64
controls the
curvature of the cushion back support 22. Therefore, the initially arced,
convex cushion back
support 22 will be progressively and continuously flattened as the tilt
pressure-responsive rod
64 rides down the inclined guide blocks 42 and 46 and against the opposing
friction-reducing
sheet 71 at the underside of back support 22.
[0032I When the user shifts his weight forwards in the chair 3 and the
compressive force being
applied to the chair back 20 teiniinates, the previously-bent tension strap 52
will automatically
rotate (in a clockwise direction) back to its original position within the
chair back, and the tilt
pressure-responsive rod 64 will be simultaneously pulled by the tension strap
52 up the ramped
surfaces 46 and 48 of the pair of inclined guide blocks 42 and 44 until the
rod 64 is engaged by
the stops 49 and 50. At the same time that the tilt pressure-responsive rod 64
rides up the guide
blocks 42 and 44, the slightly bent posture-maintaining sheet 40 will release
its stored energy
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and recover, and the previously flattened cushion back support 22 will
progressively regain its
arced, convex configuration as shown in FIG. 1 to once again protrude towards
and support the
user's lower back.
[0033] As was previously described, should an adjustment or repair of the
lumbar support be
required during manufacture of the chair 3, an uplifting rotational force is
applied to the
cushion back support 22. In this case, the back support 22 will rotate
upwardly at the hinges 72
in a counter-clockwise direction relative to the backing 24 from the folded
closed position of
FIG. I lying opposite backing 24 to the unfolded open position of FIG. 4
standing upwardly
from the backing 24. Likewise, the hinges 72 permit the cushion back support
22 to pivot and
shift relative to the rigid backing 24 when the back support is in its folded
closed position and
the tilt pressure-responsive rod 64 is being pushed and pulled up and down
over the inclined
guide blocks 42 and 44 in response to the chair back 20 tilting back and
forth.
[0034] Turning now to FIGs. 6 and 7 of the drawings, the inclined guide blocks
42 and 44 and
the hinges 72 of the chair 3 described while referring to FIGs. 1-5 are
replaced by a pair of
combination one-piece inclined rod guides and couplers 80. The one-piece
combinations 80
facilitate the movement of a horizontally-extending tilt pressure-responsive
rod 82 through the
chair back 84 of a chair 3-1 in response to the chair back tilting backwards
and forwards and a
compressive force being applied to the cushion back support 22 thereof.
[0035] In particular, each of the combinations 80 includes a base plate 86
affixed to the top of
the rigid backing 24 of the chair back 84 and a guide plate 88 which bends
upwardly from the
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base plate 86. The base plate 86 has a sloping or ramped slot 90 formed
therein. In the
assembled chair configuration of FIG. 6, opposite ends of the tilt pressure
responsive rod 82 are
adapted to slide up and down the sloping slots 90 as the tension strap 52 to
which the tilt
pressure-responsive rod 82 is connected rotates to correspondingly push or
pull the rod in the
manner previously described when referring to FIGs. 1-5. The sloping slots 90
have a
generally oval shape to surround and thereby retain the ends of the tilt
pressure-responsive rod
82 therewithin as the rod slides therethrough. The tilt pressure-responsive
rod 82 is
surrounded by a set of rollers 91 to facilitate the movement of rod 82 along
the optional
friction-reducing sheet 71 or the posture-maintaining sheet 40. The tilt
pressure-responsive rod
82 also has removable end caps 92 to permit the opposite ends thereof to be
located within the
sloping slots 90 formed in the guide plates 88 of the pair of combinations 80.
The end caps 92
may be mated to the rod 82 so as to be received by and roll along slots 90.
[0036] The base plate 86 of each combination inclined rod guide and coupler 80
has a hollow
cylindrical sleeve 94 formed at one end thereof. A pair of bracket plates 96
are affixed to the
top of the cushion back support 22. Each bracket plate 96 has a hollow
cylindrical sleeve 98 at
one end thereof. The respective hollow sleeves 94 and 98 of the base plates 86
and the bracket
plates 96 are axially aligned with one another, and coupling pins 100 are
inserted therethrough.
The coupling pins 100 pivotally connect the cushion back support 22 to the
rigid backing 24 of
the chair back 84 so that the back support 22 can be rotated between its
aforementioned folded
closed and unfolded open positions as has been previously disclosed.
