Liquid back support pad for inclined surfaces

A pad for providing liquid support on inclined surfaces includes a membrane envelope having two large parallel faces a plurality of collapsible perforated ribs, horizontally oriented within the envelope securing the parallel relationship of the faces, and a plurality of sponge-like bars received between adjacent ribs within the envelope each bar having an uncompressed volume slightly greater than that defined between adjacent ribs and the faces. A liquid fills the capillary or wicking structure of the sponge-like bars within the envelope. The combination of the sponge-like bars, the flexible ribs and atmospheric pressure maintain a hexahedral configuration of the liquid filled pad on an inclined surface.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to a liquid filled enclosure for supporting the human 
body on an inclined surface. 
2. Description of the Prior Art 
Liquid support systems for human beings typically include a relatively 
rigid frame enclosing a flexible membrane envelope filled with a liquid. 
The supported body generally "floats" horizontally on the membrane of the 
envelope. 
The comfort and "therapeutic value" of such floatation systems are 
generally thought to relate to the degree which the supporting membrane of 
the envelope conforms to the surface of the supported body. The degree of 
conformity is primmarily determined by the relative ratio of liquid volume 
within the envelope to total envelope volume, i.e., the capacity of the 
envelope to accommodate liquid displaced by the supported body. In 
essence, the membrane envelope containing the liquid typically is not 
"liquid full" even when supporting a person. 
Such partially filled liquid floatation systems have been extensively 
developed for horizontal surfaces. In such systems, the vertical walls of 
the enclosure contain the fluid displaced by the supported body. The 
displacement occurs evenly across the horizontal surface. However, 
horizontal floatation systems are not suitable for inclined surfaces. 
In particular, on an inclined surface, gravity causes the liquid within the 
envelope to pool at the lowest point, a phenomenon that is referred to as 
"puddling". In essence, a liquid filled envelope will "flow" or "stream" 
down an inclined surface over any restaining wall. 
SUMMARY OF THE INVENTION 
A liquid support pad for inclined surfaces is described which includes a 
relatively inelastic membrane envelope having two large parallel faces, a 
plurality of collapsible perforated ribs within the envelope securing the 
parallel relationship of the faces of the envelope, and a plurality of 
sponge-like bars received between the adjacent ribs within the envelope 
and a liquid within the envelope having a volume less than that of the 
envelope, and means for bleeding vapor from the envelope volume such that 
atmospheric pressure compresses the faces of the membrane envelope against 
the sponge-like bars. 
The invented liquid support pad maintains a thin hexahedral configuration 
on an inclined surface without puddling, does not require any restaining 
barrier to prevent it from "flowing" or "streaming" down the inclined 
surface, and yet, allows sufficient flexibility to the faces of the 
envelope enabling them to conform to the surface of both the incline and 
the supported body. 
Particular embodiments of the invented liquid support pad include an upper 
chamber for receiving displaced liquid, a bottom reservoir chamber and 
means for securing a flexible heating pad adjacent one of the faces of the 
envelope. Also the components of the envelope membrane, the sponge-like 
bars, and/or the flexible support beam may be impregnated with an 
anti-bacterial agent. 
Finally, for particular applications, the exterior surface of the envelope 
membrane may be "wettable" to provide a "wet" thermal contact between the 
pad and the supported body. 
Still other advantages of the invented liquid support pad relate to its 
portability, its relative "thinness" and the latent properties of liquid 
to store and release thermal energy.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIG. 1, the invented liquid support pad 11 includes an 
envelope 12 held in a hexahedral configuration with two large parallel 
faces 13 by a plurality of collapsible perforated ribs 14 and a plurality 
of foam or sponge bars 16 between adjacent ribs. 
Each collapsible rib 14 is formed from two longitudinal strips 17 welded 
together along both longitudinal edges forming a hollow tube. Opposite 
longitudinal sides of the tube are welded to the interior surface of each 
face 13. Accordingly, each rib 14 will collapse when subjected to a 
compressive force. There are holes or performations 19 through the ribs 14 
to allow fluid to move from one region within the envelope to other 
regions. 
The foam/sponge bars 16 are placed between each pair of ribs 14. The 
sponge/foam bars 16 should provide very little resistance to compression, 
yet provide or define a good internal wicking or capillary structure for 
retaining or holding a liquid such as water. 
Referring now to FIGS. 1 and 2, at the respective top and bottom ends of 
the pad are chambers 21 and 22 which do not include sponge/foam bars 16. 
The top chamber includes an port 23 through which liquid can be introduced 
into or expelled from the pad 11. The port 23 should include a bleed valve 
mechanism 24 to allow vapor to be expelled from the envelope. The lower 
chamber 22 acts as a liquid reservoir. The upper chamber 21 acts as a 
liquid expansion volume. 
A wide flexible sheet 26 is secured across one of the faces 13 of the pad 
11 providing a sleeve 27 appropriately dimensioned for receiving a 
conventionally sized electrical heating pad 28. 
The pad 11 is filled with a liquid material 29 such as water to 
approximately the level of the port 23. Then by squeezing the pad, air is 
bled from the upper chamber 21 utilizing the bleed valve mechanism 24 
(shown schematically in FIG. 2). 
The combination of the collapsible ribs 14, the sponge/foam bars 16, and 
atmospheric pressure maintain the thin hexahedral configuration of the pad 
11 on surfaces inclined near vertical such as a car seat. In particular, 
after the air is bled from the envelope 12, (accomplished by compressing 
the pad squeezing liquid from the capillary structure of the foam/sponge 
bar into the upper chamber 21 displacing the air or vapor) the pad is 
released whereupon the capillary structure of the bars 16 wicks up almost 
all of the liquid effectively reducing pressure within the envelope to 
slightly less than atmospheric. The sponge bars 16 expand outwardly 
against the envelope faces 13 held by atmospheric pressure. The expansion 
of the foam/sponge bars against atmospheric pressure effectively maintains 
a semi-rigid structure within the pad. In effect, the tendency of the 
liquid to puddle at the bottom of the envelope is effectively 
counter-acted by the syringe-like effect of the foam/sponge bars 16. The 
ribs 14 maintain the faces 13 of the envelope parallel. Accordingly, the 
envelope cannot "flow" or "stream" down an inclined surface. 
Referring now to FIGS. 2 and 3, ideally the ribs 14 and foam/sponge bars 16 
are oriented horizontally. However, the horizontal orientation of the bars 
and ribs 14 and 16 respectively only adds slightly to the integrity of the 
pad. 
When the pad is supporting a body, the flexibility of its faces 13 allows 
them to conform to the surfaces between which it is placed. In particular, 
when compressed between two surfaces, envelope volume decreases to the 
volume of the liquid in the envelope, i.e. the envelope becomes liquid 
full. Under such conditions, the liquid flows through the capillary 
structure of the foam bars 16 and via the perforations 19 through the ribs 
14 to different regions within the envelope. The liquid expelled from the 
capillary structure of the foam/sponge bars 16 is received in the upper 
chamber 21. 
A heating pad 28 can be connected to an appropriate source of electrical 
current or other source of thermal energy to provide heat. The heat warms 
the liquid within the pad. In particular, the liquid within the pad forms 
a large thermal reservoir capable of storing a substantial increment of 
thermal energy. The thermal energy stored by the liquid within the pad is 
then available for release to the supported body by thermal conduction. 
Also, the described pad may be laid across the surface of a body where the 
body supports the pad rather than vice versa. The weight of the liquid 
material in the pad conforms the face 13 of the pad to the surface 
supporting it. 
To enhance the thermal conduction from the pad to the supported or 
supporting body, the exterior surface of the envelope may be wettable to 
establish a "wetted" contact between the exterior surface of the pad and 
the supported or supporting body. 
The invented liquid support pad 11 is also extremely portable. In 
particular, while the pad when filled with a liquid may be quite heavy, 
the liquid can be expelled from the pad by simply removing the electrical 
heating pad 28 opening the port 23 and rolling the pad up beginning at the 
lower chamber 22. In this fashion the liquid is expelled from the 
capillary structure of the foam/sponge bars 16 into the upper chamber 21 
and out the port 23. The pad can then be tied or secured in the rolled-up 
position and carried about easily. 
Also to prevent bacterial growth, any component of the liquid support pad 
may be impregnated with an anti-bacterial agent. 
While the invented liquid support pad has been described in context of a 
particular embodiment, variations and modification of the pad may be made 
without departing from the scope of the invention as set forth in the 
appended claims.