Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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B~fK~EST
FIELD OF INVENTION
This in~rention relates to backrests or suppvrts. Whilst
it is particularly described in relation to light, portable backrests
it is not necessarily restricted thereto.
B~CKGR0UND OF INVENTION
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Backache has keen aptly termed a univers~al affliction,
it bein~ estimated that sc~e 80 percent of the woI-ldsl population
experiences back problems at some period of their lives. In
Nbrth kmerica some 3 to 4 percent of the populace is said to ke
afflicted to an extent to be considered at least partially disabled.
Conventional treatments include the use of orthopedic braces to hold
the kack immobilel to a greater or lesser extent for prolonged
periods of time. Such braces vary from plaster o~ Paris body
casts, to hard leather devices which are strapped to t}le body, but
to which -the body conforms rather than the support conform mg to
the body unless custom fitted. Whilst is is considered to be
preferable that a kack support be structured to the bady measurements
of individual users, this is not prackical m relatively low cost
items,
2~ In the case of chronic suffers of kack problems correct
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posture can often offer relief. Uhfortunately most ch~ir bac~s
do not provide proper support, particularly in the lu~ar region
of the spine.
It is then, an object of this invention to p~-ovide a
backl^est which aids in providing good posture and supEc)rt for
the back.
It is a further object of the invention to provid~ a
light, portable backrest of the above type.
It is another object of the invention to provide a
backrest which has a resilience in lateral direction to conform
to various body shapes/ but which is relatively stiff in longitudinal
directions so as to support the back.
It is yet another object of the invention to provide a
backrest having adequate stiffness but which is ventilated to
enhance user comfort.
SUMM~F~V OF INVENTION
. . _
In accordance with one aspect of -the invention, a
backrest comprises a shell support havin~ in mediaL longitudinal
section a shaLlow S shape, and in later~L section a shal:Low concave
shape, the sheLl support being relatively stiff and unyielding in
medial longitudL~iL portions and relatively resilient in transverse
medi~L portions when subject t~ norn~Lly applied back pre!ssure,
so as to tend to conform to the girth of a user.
Preferably the shell support comprises a central portion
having oppos~d w mg portions projecting therefrom at each side
thereof in a unitary structure. Desirably the thickness of the
shell support reduces progressively in passing frGm the centr~L
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portion to the wing portions, so as to increase the lateral
resilience of the shell supportr although such resilience must
always be commensurate with the wing portions having adequate
stiffness to provide support to the back of a user of the backrest.
It is additionally preferred that the ~edial longitl~Lnal
p3rtions of the shell support ke proportioned 50 that the area
of inflexion of the S shape locates at about mid height o-f
such p~rtions.
In accordance with another aspect of the invention the
shell support is provided with a plurality of openlngs therein
to permit the escape of heat therethrough. Desirably a pair of
laterally e,longated window openings are pro~ided for this purpose,
these w mdow openings further serving to increase the resiliency
of the shell support in lateral planes. These laterally elongated
window openings intersect the longitudinc~l medial section of the
shell support akove and below the area of infle~ion xespecti~ely;
t~e backrest is normally used wh~rein the window openings o~erlay
mid sections of the thoracic vertebrae and mid sections of the
lumkar vertebrae respectively. As a corollary, non-wi ~ owed
sections of the shell support locate to support upper and lo~r
portions of the thoracic vertebxae clnd lumbar vertebrae
respectively.
In accordance with yet another aspect of the invention
the kack support :is up,holstered on the concave side thereof with
a soft, resilie,nt sponge material, this in turn being covered with
a cloth oover which is prefe,rably stretchable in a lateral direction,
the cloth cover sE~mning between the laterally o~posed margins of
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the back suppor~ ullder tension so as to be unsupported in madi,~l
portions thereof and ~reate an air pocket bet~een the cover cl~1
support, which air pocket is collapsible to expel air therefran and
ventilate the backrest.
The above objects and asp~cts of my invention will
made more clear, and still others and the advantages thereof
will become e~vident from the following disclosure of a preferred
embodiment of the invention, taken in conjunction with the
acccmpanying drawings.
BRIEF DESCRIPTION OF DRAWINGS
.
FIGo 1 ~ shows the backrest of the invention in a
frontal perspective view;
FIG~ 2 - shows the backrest of FIG. l rotated
through akout 180 about its longitudinal
axis;
FIG~ 3 - shows an interior shell frame of the
backrest in frontal perspective view;
FIG~ 4 ~ is similar to FIG~ 3, but shows an
alternative emkodiment of the shell frame;
FIG. 5 - is similar to FIG. 2, but shows the
upholstexy partially cut away to reveal
internal detail;
FIG~ 6 ~ is a view partly in section along 6-6 of FIG~
5;
~5 FIG~ 7 ~ is a sectional view along 7-7 of FIG~ 6, and
FIG~ 8 ~ sh~ws Ln side elevation a back support
in use.
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DESCRIPTION OF P~EFERR~D EMBODDMENT
__ _
Referring -to the drawings in detail~ a backrest is
indicated generally therein by the numeral 10. Backrest 10
comprises a shell support 12 h~ving a central portion 14 and
opposed wing portions 16 which project frcm each side thereof~
the wing portions increasing generally in their lateral dimension
on approach to the lower areas of the backrest. Shell support 12
is generally arcuately forme~ with a shallow concave section taken
laterally, as seen in Fig. 7. In medial longitudinal section shell
support 12 is a shallow S shape, best seen in Fig. 6, corresponding
generally to the normal curvature of the spine of a person in an erect
position taken betwee~ the lower lumbar ~ertebrae and about the
fourth upper most thoracic vertebrae, the area of infle~i~n 18 of
the S shape thereb~ locating at about mid height of central portion 14.
The sh~llow S shape of the shell support extends outwardly to the
lateral margLns 20 of the shell support, as seen best in Fig. 3.
Shell support 12 has a pair of relatively large
laterally elongated window openings 22,24 which extend from
adjacent ~pposed lateral margins 20 respectively thereby forming
three relatively broad horizont~lly spaced back support areas or
bands 26,28,30, band 28 being generally coincident with zone of
inflexion 18 at least in medial portions of the shell support.
Shell support 12 is typically moulded in a plastic
material having a relatively high shear modulus,polycarbonate
res~n and glass fibre reinforced thermosetting polyester resins
having been found to be particularly satisfactory because of the
relatively high stifEness afforded by m~derately thin sections
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thereof. T~pically ~dial sections of shell support 12 will have a
thickness of sane 3.5 to 4 mm, this decreasing by some 20 percent on
approach to lateral margins 20.
Shell support 12 is upholstered with a layer of sp~ngy foam
material 32 adhered to the concave side of the support, a th mner layer
34 of spongy foam material on the backside of the support completing the
envelope. Preferably foam material layers 32,34 are open celled to pe~mlt
the passage of air and moisture vapour therethroughO A fabric cover 36 in
its turn envelopes the foam layer. Fabric cover 36 is stretched
relatively tightly between the lateral margins 20 of shell support 12, to
leave an air space 38 bekween the cover and foam layer 32. Fabric cover
is preferably of a knitted material cut so as to be prefera!bly stretchable
in the lateral direction. Cover 36 is provided with a lateral separable
seam 40 joined by a Velcro fastener or the likeO
Velcro is a trade mark for a nylon material made with both a
surface of tiny hooks an~ a ccmplementary surface of an adhesive pile
that can be pressed together or pulled apart for easy faste~ing or
unfastening.
In a further embodlment of the invention shown in Fig. 4, a
shell support 112 is provided with a plurality of openings 114 the~ein
distributed generally uniformly over the surface of -the support within
the margins t~lereof, shell support 112 being otherwise identical to
shell support 12.
Havin~ descriked the structure of backrest 10 the nkmner of
use will now b~ clescribed- Backrest 10 is typically in-terposed be~-ween
the back of a p~t-son and a support mg chair back 42, where the person
is seated, as s~wn in Fig. 8. It will be appatent that kackresk 10
cc)uld be ~mified with the seating portion 44 of the chair, or otherwise
be integratecl into the structure of the chair or indeed any other structure
upon which the frame of a pexson is reposed. A~vantages of the separable
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structure reside in its portability, and also the ease of
adjustment. Desirably when used ~ackrest 10 is positioned so
that horizontal support areas 26,28,30 of shell support 12 support
upper portions of the thoracic spine, :Lo~er portions of the lumbar
5 spine, and the vertebrae where the thoracic spine and lum~ar
spine meet.
When ~ack pressure is initiaLly applied to cover 36 the
cover stretches in conformity with the users' back, thereby
assisting in delocalizing pressure thereon. As the pressure applied
to backrest 10 increases, -the concavity of shell suppoxt 12 is
proyressively decxeased; LateraL margins 20 thereby moving apart.
This movement of the lateraL m~rgins in its turn further stretches
cover 36, still further assisting in the delocaLization of
pressure experienced on spinaL areas of the back of a user, with
somewhat increased pressuxe being experienced in the wing æ eas.
It will be appreciated that whilst foam layer 32 acts to delocalize
pressure, it is of assistance in reducing relative ~v~ment between
cover 36 and shell support 12 adjacent margins 20 of the shell
support. Cover 36 also assists in ventilating backrest 10. m us
as pressure is alternately applied to and released frcm cover 36
the volume of air space 38 will vary, with air being alternately
expelled fram ~nd aspirated into the air space, air thus being
caused to circulate through the cover and through the open celIed
foam layers 32 and 34.
Whilst in the illustrated emkodiments presently preferred
fe~atures of the invention have been put forward, it is to be
understood that the invention is not li~ited to the precise forms
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illustrated, and that changes may be ~ade thereto without
departing from the spirit and substance of the invention.
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