U.S. patent number 3,794,382 [Application Number 05/196,484] was granted by the patent office on 1974-02-26 for support systems for the seated human body.
This patent grant is currently assigned to British Railways Board. Invention is credited to Jack Bloomfield, Paul Branton, Kenneth Grange.
United States Patent |
3,794,382 |
Bloomfield , et al. |
February 26, 1974 |
SUPPORT SYSTEMS FOR THE SEATED HUMAN BODY
Abstract
A support system for the seated human body comprising a
two-dimensional material such as a length of netting constrained
under tension to define a three-dimensional support form including
in an upwardly extending length of the material a localised
forwardly projecting support portion for the upper pelvic/lumbar
area of the human body, the tension in the forwardly projecting
support portion being preferably higher than in the remainder of
the upwardly extending length of the material. In a generally
horizontally extending seat portion the tension in a zone
immediately forward of the ischial tuberosities supporting zone is
preferably higher than the tension in the ischial tuberosities
supporting zone itself.
Inventors: |
Bloomfield; Jack (London,
EN), Branton; Paul (London, EN), Grange;
Kenneth (London, EN) |
Assignee: |
British Railways Board (London,
EN)
|
Family
ID: |
26262912 |
Appl.
No.: |
05/196,484 |
Filed: |
November 8, 1971 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
878849 |
Nov 21, 1969 |
|
|
|
|
Foreign Application Priority Data
|
|
|
|
|
Nov 27, 1968 [GB] |
|
|
56,324/68 |
Jul 16, 1969 [GB] |
|
|
35,924/69 |
|
Current U.S.
Class: |
297/452.13;
297/440.11; 297/452.3 |
Current CPC
Class: |
A47C
7/029 (20180801); A47C 7/282 (20130101) |
Current International
Class: |
A47C
7/02 (20060101); A47c 007/02 (); A47c 001/08 () |
Field of
Search: |
;297/216,217,196,445,452,456,457 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
1,433,694 |
|
Aug 1966 |
|
FR |
|
810,441 |
|
Mar 1937 |
|
FR |
|
774,614 |
|
Dec 1934 |
|
FR |
|
Primary Examiner: Gilliam; Paul R.
Attorney, Agent or Firm: Vande Sande; George
Parent Case Text
This is a continuation of application Ser. No. 878,849, filed Nov.
21, 1969 now abandoned.
Claims
We claim:
1. A support system for the upright seated human body
comprising,
a supporting frame including back support means,
a flexible web material constrained under tension on said back
support means to define a three-dimension back support form,
said back support means including pelvic-lumbar support means at
the upper pelvic-lumbar area of the human body,
said pelvic-lumbar support means supporting said flexible web
material with a configuration such that said back support form
defines a first support portion which extends laterally of said
back support form and is positioned forwardly of the rest of the
flexible web material forming the back support form,
said first support portion of said back support form being
constrained in tension across its width by said pelvic-lumbar
support means,
said back support means having additional means at second and third
locations which are respectively above and below said first support
portion which constrains said flexible web material so that the
upwardly extending length of said material extends both upwardly
and rearwardly and also downwardly and rearwardly from said first
portion to define thereby said back support form,
said flexible web material being unsupported across the width of
the back support form by said back support means between said
additional means at said first and third locations.
2. A support system as claimed in claim 1, wherein the tension of
said flexible web material in said first support portion is higher
than in the remainder of said upwardly extending length of said web
material.
3. A support system as claimed in claim 1 wherein in a generally
horizontally extending seat portion the tension in a zone
immediately forward of the ischial tuberosities supporting zone is
higher than the tension in said ischial tuberosities supporting
zone.
4. A support system as claimed in claim 3 wherein forward of said
zone of higher tension up to the front edge of said seat portion
the tension of said material is less than in said zone of higher
tension.
5. A support system as claimed in claim 1, wherein the supporting
structure includes two side frames provided with slits in which the
side-edges of the material are trapped.
6. A support system as claimed in claim 5, wherein the spacing of
said side frames is adjustable in order to vary the transverse
tension in said material.
7. A support system as claimed in claim 6, wherein said side frames
are interconnected through a lead-screw arrangement enabling the
adjustment of said side frames.
Description
This invention relates to support systems for the seated human
body.
The object of this invention is to provide a support system for the
seated human body which is of lightweight construction and which
stabilises effectively certain parts of the seated human body
without the use of conventional upholstery whilst providing for
optimal sitting comfort.
According to this invention in its broadest aspect, a support
system for the seated human body comprises a substantially
two-dimensional tensionable material constrained under tension by a
supporting structure to define a three dimensional support form
including in an upwardly extending length of said material a
localised forwardly projecting support portion for the upper
pelvic/lumbar area of the human body.
Since in accordance with the present invention the human body is
not supported through padding or the like but simply by the said
material under tension, dissipation of heat generated at the
interface between the body and the support system is facilitated
and can be further improved if said material is, for example, in
the form of netting.
In the ideal support system in accordance with the invention said
localised forwardly projecting portion provides a sacral support
region, but as will be appreciated hereafter from the description
with reference to FIG. 1 of the accompanying drawings, because of
the variation in size of human beings the upward extent of said
localised forwardly projecting portion will extend into the lumbar
area of some human beings.
For an understanding of the present invention it must be recognised
that the human body is essentially a system of open-chain links
and, particularly in the seated posture, is inherently unstable
without the intervention of muscle activity. Head, trunk, arms and
legs are flexibly linked and within these body parts there are yet
further flexible links, notably that between the pelvic bone and
the lumbar vertebrae. Scientific investigation has shown that in
the sitting posture the pelvis normally rocks over the ischial
tuberosities unless the uppermost backward extension of the pelvis
itself is stabilised by leaning against a surface relatively
rigidly connected to the surface on which the ischial tuberosities
rest. Furthermore, unless the pelvis is restrained from rocking or
rotating slowly, the ischial tuberosities will tend to slide
forward on the seat due to the weight of trunk, head and arms, so
that the lumbar spine is no longer supported by the back-rest. This
is considered by most orthopaedic authorities an unhealthy posture
contributing to lower back complaints.
By achieving stabilisation is not meant complete immobilisation of
the pelvis in one specific posture but that a stable effect is
obtained over a range of positions normally considered as
sedentary. The main reasons for seeking such stability are firstly
on health grounds it is undesirable that the spinal ligaments
should be subjected to the strain imparted to them by the said
rocking or rotation of the pelvis. Secondly, on grounds of sitting
comfort stability of the pelvis saves muscle effort and hence
encourages relaxation.
In further development of the present invention, said material is
more highly tensioned immediately forward of its ischial
tuberosities supporting portion than at the latter portion in order
to assist in restraining the human body from sliding forward.
The invention will now be further explained with the aid of the
accompanying drawings, in which:
FIG. 1 shows in side view the basic profile of the support
system,
FIGS. 2 and 3 are front and rear perspective views of one
embodiment of the invention,
FIG. 4 shows a side view of a second embodiment,
FIG. 5 shows the adjustability of two side frames of the embodiment
of FIG. 4,
FIG. 6 shows a detail of the side frames,
FIG. 7 shows the adjustment arrangement for the side frames
and,
FIGS. 8 and 9 show alternative ways of trapping the netting in the
side frames.
In the embodiments shown in FIGS. 2 to 9 the support system for the
seated human body comprises a single length of netting material
held along its lateral edges and along its upper and lower edges
under tension in a supporting structure to define a generally
horizontal seat portion and an upwardly extending back supporting
portion. In FIG. 1 is seen in side view one example of the contour
which a length of material follows in accordance with the
invention, the chain-dotted lines indicating generally the way in
which the material would be deformed along its centre-line (i.e. at
the mid-width of the material) by a seated person in the sacral
supporting zone and in the ischial tuberosities supporting
zone.
On FIG. 1 have been indicated the distances x, y, z.sub.1, z.sub.
2, and z.sub.3. For 90-95 percent of the adult population seated in
the support system, if the distance x is five inches and the
distance y is six inches and the distances z.sub.1 and z.sub. 2 are
about four inches, their ischial tuberosities will rest in the zone
defined by z.sub.1 and their sacrum will rest in the zone defined
by z.sub.2. In accordance with the invention therefore it is in the
zone z.sub.2 that the forwardly projecting portion of the upwardly
extending length of material is provided and advantageously the
tension of the material at least in the upper part of this zone is
higher than in the remainder of the upwardly extending portion. As
regards the area below the zone z.sub.2 it is essential that the
material sweeps backwardly as shown so that this does not come up
against a seated person and tend to push him forwardly. Also in
order to assist in restraining the body from sliding forwardly the
material in the zone defined by z.sub.3 and immediately forwards of
the ischial tuberosities zone z.sub.1 will be at a higher tension
than in the zone z.sub.1. The tension of the zone forward of the
zone z.sub.3 is advantageously fairly low in order to provide
comfort under the knees of the sitter. Likewise the tension in the
material above zone z.sub.2 is advantageously sufficiently low for
the material to wrap to some extent around the back of the sitter
to provide lateral stabilisation.
Referring now to the first embodiment shown in FIGS. 2 and 3 the
support system has a supporting structure comprising a curved spine
1 from which extend various frame members which define arm rests 2,
back frame 3 and head-rest frame 4.
Netting 5 is suspended from the arm rests 2 and is constrained by
cords 6 or shaped by stitching. The netting continues upwards to
form the back rest and has a forwardly projecting portion which is
held taut by back frame 3 in such a way that firm support is given
in the upper pelvic/lumbar area. The netting 5 also forms the head
rest on the head-rest frame 4.
The spine 1 extends to the floor. It may be hinged to tilt the seat
backwards. It is essential in this embodiment that the tilting
should not cause the leading edge of the seat to be raised. Recline
may be controlled hydraulically. In an alternative construction,
where the framing continues down to the floor on both sides of the
seat, another method of reclining the seat would have to be
adopted.
Referring now to the second embodiment shown in FIGS. 4 to 9 of the
drawings, the length of netting 30 forming the body support system
has the general contour shown in FIG. 1 and is supported between
two side frames 11 and 12. Each side frame 11 and 12 is slidably
supported on a cross beam 13 so that in constructing the seat the
spacing between the side frames 11 and 12 can be adjusted. To
effect this adjustment a lead screw arrangement 14 is provided
between inwardly extending members 15 of the side frames 11 and
12.
Each side frame 11, 12 has a curved hollow metal or plastics
extruded member 16 for example of aluminum, formed with a
continuous slit 17 along it opening into the interior of the
extrusion. Secured to the lower end of the member 16 is arm rest
member 18.
Each side frame 11, 12 also has hollow aluminum extruded member 19
bent to angular form so that it extends from the front to the back
of the seat portion and then extends upwardly to join with the
curved member 16. At the front of the seat portion the member 19 is
attached to the arm rest member 18. The member 19 also has a
continuous slit 20 extending along it. As can be best seen from
FIG. 5 at the front of the seat the slit 20 aligns with a slit 21
formed in the arm rest 8 and which curves generally downwardly.
The length of netting 30 extends between the two side frames 11 and
12 and has its side edges trapped in the various slits mentioned.
Thus proceeding from the front of the seat, the side edges of
netting 30 follow slits 21 and 20 to the rear of the seat portion.
They then leave members 19 through slots 22 and extend to members
16, into the slits 17 of which they are entered through slots 23.
Thereafter the side edges of the length of netting follow the slits
17 up the back portion of the support system. At the top of the
back portion the end edge of the netting is trapped in cross member
24.
The side edges of the netting 30 may be trapped in the members 16
and 19 in the manner shown in FIG. 8. Thus a cord 35 is threaded
through a hem in each side edge of the netting, the cord being
wider than the slits 17 and 20. Alternatively it may be trapped in
the manner shown in FIG. 6 where a side runner 26 of PVC is heat
sealed to the side edges of the netting 30, the side runner 26
having a portion 27 trapped in the hollow of the extruded member
16, 19.
To fit the netting 30, the side frames 11 and 12 are initially
spaced apart a distance less than their spacing in the finished
seat. The netting is then fitted in the side frames 11 and 12 and
to the cross member 24. Afterwards the net is transversely
tensioned by the lead screw arrangement 14 which moves the side
frames 11 and 12 apart.
Finally the cross member 24 is fitted. It can be arranged by
careful tailoring of the length of netting 30 that when the spacing
of the frames 11 and 12 corresponds to the finished dimensions of
the seat, the netting 30 is correctly tensioned.
To provide zones of different tension in the length of netting 30
the latter may be cut on the bias in predetermined zones.
Alternatively the netting may have a different composition in
predetermined zones, or provided with reinforcement.
* * * * *