Note: Descriptions are shown in the official language in which they were submitted.
SOLITON TRAVELING WAVE AIR MATTRESSES
BACKGROUND OF THE INVENTION
A. Field of the Invention
The present invention relates to mattresses of the type used to
support a recumbent human. More particularly, the invention relates to novel
air
mattresses which have an array of individually inflatable and deflatable air
bladder
cells that receive air pressure pulses in a timed sequence which results in a
soliton
traveling wave of body support force variation to traverse the surface of the
air
bladder cells. The soliton body support forces waves can be programmed to
travel
longitudinally, laterally or obliquely on the upper support surfaces of the
air bladder
cells, according to pre-determined patterns which can be used to minimize
formation of decubitus sores on a patient's body and alternatively to simulate
comforting motions such as floating on a rolling water wave, or rocking in a
boat,
which simulations may optionally be accompanied by appropriate music and/or
environment-simulating sounds.
B. Description of Background Art
Pressure sores, which are also known as decubitus ulcers or bed
sores occur in the outer tissues of a person's body if parts of the body are
subjected
to relatively large normal force pressure gradients, and/or tangential or
shear forces,
for long periods of time. Such sores are caused by reduction in blood
circulation
caused by surface force pressures which exceed the person's capillary blood
pressure. The problems with bed sores forming on the skin of persons with
medical
conditions which require them to be in relatively immobile positions on a
hospital
bed or in a wheel chair can be severe, resulting in painful, difficult to
treat
conditions, loss of limbs, or even death.
For the foregoing reasons, hospitals, nursing homes and other such
health care facilities which provide care giving to ailing or elderly people
are keenly
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aware of the necessity for carefully monitoring people under their care to
prevent
formation of bed sores. A commonly used method to minimize the possibility of
bed
sore formation is to turn the patient periodically, i.e, to re-adjust the
patient's
position on a bed mattress or in a wheel chair so that long-term normal force
pressure gradients, can be relieved from parts of a patient's body. However,
turning
invariably results in renewed higher pressures on other parts of the body, so
the
turning process must be repeated usually at least on a daily basis.
Presumably in response to a perceived need for reducing problems of bed
sore formation, a variety of devices and methods have been proposed to reduce
long-term, large force or pressure concentrations on a person's body. For
example,
Cottner et al, in U.S.Patent No. 5,243,723, September 17,1993, Multi-Chambered
Sequentially Pressurized Air Mattress With Four Layers discloses an air
mattress
which has two lower layers constantly pressurized at about 1 psi gauge, and
two
upper layers that each have serpentinely shaped, transversely disposed
interdigitated membrane areas which are cyclically and alternately pressurized
with
varying air pressure in a push-pull fashion which creates a standing wave of
variation in support force for a patient, with the intended purpose of
minimizing
formation of decubitus sores. The standing waves produced by alternate
inflation
and deflation of adjacent interdigitated members shifts support forces up and
down,
leaving the average maximum reaction support force concentrations on parts of
a
patient's body unchanged. Moreover, the continuous oscillating motion of the
interdigitated members exerts continuous reciprocating tangential or shear
forces on
parts of a body supported by adjacent interdigitated members, which shear
force
can collapse blood vessels and thus reduce blood circulation, which can
contribute
to the formation of shear-force induced decubitus sores.
The present invention was conceived of to provide air mattresses
which provide soliton traveling waves of support-forces for the body of a
person
supported by the mattress, which can reduce maximum force concentrations of
the
type that can lead to the formation of decubitus bed sores.
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OBJECTS OF THE INVENTION
An object of the present invention is to provide a soliton traveling wave
air mattress apparatus which includes an inflatable air mattress that has a
multiplicity of hermetically isolated air bladder cells and a pressure pulse
generator
which dynamically varies inflation pressures in the cells to thus create a
soliton
traveling wave of support-force which travels over the upper surface of the
mattress.
Another object of the invention is to provide a soliton traveling wave air
mattress apparatus which includes a mattress that has a multiplicity of
laterally
disposed, hermetically isolated air bladder cells, and an air pressure pulse
generator which sequentially varies air pressure in the cells to thus create
longitudinally traveling soliton body support-force waves on the upper
surfaces of
the air bladder cells.
Another object of the invention is to ;provide a soliton traveling wave
air mattress comprised of a planar matrix of air bladder cells which are
hermetically
isolated from one another, and a pressure pulse generator for varying air
pressures
in the cells by pressure pulses which are applied sequentially to individual
cells or
groups of cells to create on the upper surfaces of the cells soliton traveling
waves of
support-force for the body of a person supported by the mattress, the soliton
traveling waves being directable longitudinally, laterally, obliquely, or in
other
directions on the surface of the mattress.
Another object of the invention is to provide a soliton traveling wave air
mattress which has a matrix of air bladder cells, each of which has associated
therewith a surface reaction force-sensor, the sensors being useable to
calculate a
gradient vector of surface reaction forces measured by the sensors, and a
pressure
pulse generator for directing waves of negative pressure pulses to air bladder
cells
along the path of the gradient vector to thus create a soliton traveling wave
of
support force reduction which travels in the direction the gradient vector.
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Another object of the invention is to provide a soliton traveling wave air
mattress apparatus which has a multiplicity of individually inflatable and
deflatable
air bladder cells that are hermetically isolated from one another, and a wave
generator including a pressure pulse generator and air bladder selector valves
which introduces a wave of air pressure pulses into selected sequences of
cells to
thus create a traveling wave of body support force reduction directed along
the
gradient path.
Another object of the invention is to provide a soliton traveling wave air
mattress apparatus which has a multiplicity of individually inflatable and
deflatable
air bladder cells that are hermetically isolated from one another, and a wave
generator which includes a pressure pulse generator and a selector valve
mechanism which introduces pulses of air pressure sequentially into selected
air
bladder cells in a sequential fashion that produces a soliton traveling
pressure wave
in the air bladder cells which in turn causes the upper surfaces of the air
bladder
cells to produce thereon a corresponding soliton traveling wave of support
force for
a body supported on the upper surface of the air mattress.
Various other objects and advantages of the present invention, and its
most novel features, will become apparent to those skilled in the art by
perusing the
accompanying specification, drawings and claims.
It is to be understood that although the invention disclosed herein is
fully capable of achieving the objects and providing the advantages described,
the
characteristics of the invention described herein are merely illustrative of
the
preferred embodiments. Accordingly, I do not intend that the scope of my
exclusive
rights and privileges in the invention be limited to details of the
embodiments
described. I do intend that equivalents, adaptations and modifications of the
invention reasonably inferrable from the description contained herein be
included
within the scope of the invention as defined by the appended claims.
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SUMMARY OF THE INVENTION
Briefly stated, the present invention comprehends a method and
apparatus for alleviating formation of bed sores or decubitus sores on parts
of the
body of a person such as a medical patient who is supported in a relatively
immobile
recumbent position on a hospital bed for long periods of time. The apparatus
according to the present invention includes an air mattress which is
constructed
from individually inflatable and deflatable air bladder cells which are
arranged in a
rectangular array having an upper horizontal patient support surface. The
individual
air bladder cells are inflated to suitable quiescent pressure levels which
provide
comfortable support for the body of a recumbent patient. The quiescent or bias
pressure levels of the several air bladder cells may be individually adjusted
to
values which minimize the sum of maximum reaction force concentrations exerted
on the body of a patient, as measured by an array of force or pressure sensors
which may be associated with the array of air bladder cells.
According to the invention, air pressure in each of the cells is cyclically
varied in a manner which causes the support forces afforded by the mattress
for a
human body to have superimposed on quiescent static or bias values time-
varying
pressure components to thus produce soliton traveling waves of support force
superimposed on the static support forces. Soliton traveling wave components
of a
quiescent support force are produced by varying in a pre-determined time
sequence
air pressure in sequences of individual air bladder cells according to pre-
determined
programs which control pressurized air inlet to and exhausted from individual
air
bladder cells via electrically controlled valves.
For example, to produce a soliton traveling wave of support force
reduction which travels from the head-end towards the foot-end of the
mattress, air
pressure in a first laterally disposed zone of air bladder cells located at an
end of
the longitudinal axis of the mattress near the patient's head is momentarily
reduced
to produce a pressure reduction pulse, followed by a reduction of air pressure
in air
bladder cells located in longitudinal zones successively closer to the foot-
end of the
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mattress, and so forth, until a pressure reduction pulse occurs in a last
longitudinal
zone of air bladder cells near the foot-end of the mattress. The soliton
traveling
pressure wave pulse cycle and resultant soliton traveling support force wave
cycle
can be activated intermittently, such as once every hour, continuously in
groups of
several cycles periodically or in response to sensor measurements of reaction
forces exerted on a patient.
In one embodiment of the invention, the air bladder cell matrix will
have at least two and preferably three parallel longitudinally disposed zones
located side-by-side, and preferably have at least 3 and preferably 4 or more
laterally disposed zones. For example, a 3 column X 4 row array of 12 air
bladder
cells which has four longitudinally arranged, laterally disposed zones each
three-
cells wide enables soliton traveling support force waves to be propagated
longitudinally, i.e., head-to-foot, or foot-to-head, laterally, i.e., left-to-
right and right-
to-left, and obliquely.
Under computer program control, the air pressure in individual air
bladder cells, or in groups of cells, such as in all or some of the cells in a
row or
column, can be temporarily varied from quiescent values of air pressure in a
wide
variation of time sequences to thus produce a wide variety of soliton waves of
patient support forces which travel over the upper surface of the mattress.
The
traveling soliton support wave patterns can be optimized to alleviate or
minimize the
formation of decubitus sores which can result from long periods of large
static
support pressures on parts of a patient's body.
In a simple example, the pressure in all three of the laterally arranged
air bladder cells in the first, head-end longitudinal zone of a 3 X 4 matrix
air mattress
may be reduced from quiescent steady state values by a pulse of negative air
pressure input to the cells in that zone for a period of several seconds. At
the end
of the first air pressure pulse, air pressures in the cells may be restored to
their
original bias or quiescent values, which have been previously adjusted to
provide
comfortable support of a patient.
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After an initial pressure pulse has been applied to a first air bladder
cell or group of cells, similar pressure reduction pulses are applied
sequentially to
transverse zones 2, 3 and 4. This sequence of air pressure reduction pulses
results
in a soliton traveling wave of support forces reduction which travels
longitudinally
.. from the head-end to the foot-end of the mattress.
The traveling waves of air pressure reduction pulses in the air bladder
cells can be performed as a single cycle, at pre-determined times, repeated
for
several cycles, or performed continuously for pre-determined time periods.
Also,
the time interval between an air pressure reduction pulse in one zone of air
bladder
cells and the initiation of an air pressure pulse in a subsequent zone in a
pre-
selected spatial sequence need not be zero, as it would be in a traveling wave
which characterizes water waves, but may, for example, have a finite,
selectable,
value. In other words, the duty cycle of a pulse generator used to activate
air
pressure control valves to thus apply a sequence of air pressure pulses to a
sequence of air cell bladder zones can be as small as desired. Or, put another
way,
the time interval between successive pressure pulses applied to successive
cells or
group of cells, can be as long as desired.
According to the invention, soliton traveling waves of air pressure
pulses which decrease for pre-determined time intervals and repetition rate,
the
maximum reaction force concentrations on parts of a human body can be
programmed to travel longitudinally from head-to-foot, as described in the
simplified
example above, or in the opposite, foot-to-head longitudinal direction on the
mattress surface. As stated above, longitudinally traveling soliton body
support
force waves are produced by varying the air pressure simultaneously in each
air
bladder cell in a first transverse row of cells, subsequently varying the air
pressure
in the air bladder cells in a longitudinally adjacent row of cells, and so
forth, until the
soliton wave of support forces on parts of a patient's body has traversed the
entire
length or a selected segment of the length of the mattress.
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In an exactly analogous fashion, air pressure in laterally adjacent or
spaced apart longitudinally disposed columns of adjacent air bladder cells may
be
sequentially varied to produce laterally traveling waves of body support
forces.
Also, by sequentially varying air pressure in obliquely located air bladder
cells,
obliquely soliton traveling waves of body support forces may be generated
using the
soliton traveling wave air mattress according to the present invention.
According to another aspect of the present invention, an optional force
sensor array is optionally provided which has individual surface reaction
force
sensors associated with individual air bladder cells, in vertical alignment
with
individual cells. The array of reaction force sensors, which produce
electrical
signals proportional to reaction forces exerted by the mattress on various
parts of a
patient's body supported by the individual cells, may be used to create a map
of
body reaction force concentrations.
The measured values of reaction forces may also be used to create a
segmented measured reaction force gradient vector. The reaction force gradient
vector may hen be used to calculate a path sequence for producing a soliton
traveling wave of air pressure in a sequence of air bladder cells along the
reaction
force gradient vector.
Since a measured reaction force gradient vector may not necessarily
include all of the air bladder cells in an array, and may in some cases be
directed
between non-adjacent air bladder cells, soliton traveling waves of air
pressure may
be directed individually to only a small number of the total air bladder cells
in an
array, some or all of which cells may be non-adjacent. In this way, patient
body
support reaction forces exerted by the air mattress may be momentarily and
periodically reduced in an efficient manner which does not require varying air
pressure in all of the air bladder cells in an array.
For example, if reaction force sensors determine that a maximum
reaction force is exerted by a first cell, and the force gradient vector from
that
maximum is directed through three additional cells, some of which may be non-
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adjacent, an air pressure wave need be directed only to those four air bladder
cells
to thus create a soliton traveling support force reduction wave which travels
over just
the four cells. For reasons stated above, the four cells need not necessarily
be
vertically or horizontally aligned, or adjacent to one another.
According to the invention, a basic embodiment of the soliton traveling
wave air mattress, which need not have reaction force sensors, may also be
programmed to simulate relaxing motions. Thus, longitudinal traveling soliton
support pressure waves in the mattress may be programmed to simulate motions
corresponding to floating on a surf wave, and may be accompanied by surf
sounds.
Also, laterally traveling soliton support force pressure waves can be
programmed to
simulate gentle rolling or rocking motions of a boat and may be accompanied by
water sloshing sounds and/or sounds simulating creaking oarlocks.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a partly schematic, partly perspective view of a traveling
wave air mattress apparatus according to the present invention.
Figure 2A is a fragmentary, partly diagrammatic upper plan view of an
air mattress component of the air mattress apparatus of Figure 1.
Figure 2B is a fragmentary, partly diagrammatic upper plan view of a
first modification of the air mattress of Figure 2A.
Figure 3A is a timing diagram showing relative timing and amplitudes
of negative air pressure pulses for producing soliton traveling body support
force
waves ef in the apparatus of Figure 1.
Figure 3B is a timing diagram similar to Figure 3A but showing positive
pressure pulses for producing positive soliton traveling body support force
waves.
Figure 4 is a view similar to that of Figure 2B, but showing a second
modification of the air mattress of Figure 2A having a second arrangement of
individual inflatable air cells, in which each transversely disposed row
consists of
two cells.
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Figure 5 is a view similar to Figure 4, showing a third arrangement of
air cells in which each row consists of four cells.
Figure 6 is a partly schematic, partly perspective view of a modification
of the traveling wave air mattress apparatus of Figure 1, which is suitable
for use in
health care facilities.
Figure 7A is a partly diagrammatic upper plan view of an air mattress
component of the air mattress of Figure 6.
Figure 7B is a timing diagram showing relative timing of pressure
pulses and resulting traveling soliton body support force waves of the
apparatus of
Figure 6.
Figure 8 is a diagrammatic upper plan view of a two-column by six row
modification of the air mattress of Figure 7A, showing a hypothetical reaction
force
gradient vector thereon.
Figure 9 is timing diagram showing a sequence of negative air
pressure pulses applied to the mattress of Figure 8 in the direction of the
reaction
force gradient vector shown in Figure 8.
Figure 10 is a partly diagrammatic view of a soliton wave generator
for the apparatus shown in Figure 6, which includes a reciprocating air pulse
generator.
Figure 11A is a partly diagrammatic view of another embodiment of a
traveling wave air mattress apparatus according to the present invention,
which
includes a pressure/vacuum pump, showing valves of the apparatus configured
for
producing negative air pressure in pulses to air bladder cells of an air
mattress.
Figure 11B is a view similar to that of Figure 11A, but showing valves
configured for producing positive pressure variations in air bladder cells.
Figure 12 is a partly diagrammatic view of a third, modular
embodiment of a soliton traveling wave air mattress according to the present
invention.
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Figure 13 is a partly diagrammatic view of a soliton wave generator
and air pressure pulse generator module of the apparatus of Figure 12.
Figure 14 is a partly diagrammatic view of a first type mattress
interface module and inflatable air mattress which together with the soliton
wave
generator and air pressure pulse generator module of Figure 13 comprise a
third
embodiment of a soliton traveling wave air mattress according to the present
invention.
Figure 15 is a partly diagrammatic view of a second type mattress
interface module and inflatable air mattress which together with the soliton
wave
generator and air pressure pulse generator module of Figure 13 comprise a
first
variation of a third embodiment of a soliton traveling wave air mattress
according to
the present invention.
Figure 16 is a partly diagrammatic view of a third type of air mattress
interface module and inflatable air mattress which together with the soliton
wave
generator and air pressure pulse generator module of Figure 13 comprise a
second
variation of a third embodiment of a soliton traveling wave air mattress
according to
the present invention.
Figure 17 is a partly diagrammatic view of a fourth type of air mattress
interface module and inflatable air mattress which together with the soliton
wave
generator and air pressure pulse generator module of Figure 13 comprise a
third
variation of a third embodiment of a soliton traveling wave air mattress
according to
the present invention.
Figure 18 is a timing diagram showing a first, active-deflation operating
mode of the soliton wave generator of Figure 13.
Figure 19 is a timing diagram showing a second, passive-deflation
operating mode of the soliton wave generator module of Figure 13.
Figure 20 is a timing diagram showing relative timing and amplitudes
of a sequence of air pulses input sequentially into individual air bladder
cells of the
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air mattress of Figure 17, to thus produce a soliton traveling body support
force
wave on the upper surface of the air mattress.
Figure 21A is a fragmentary, partly diagrammatic side elevation view
of the air mattress of Figure 17, showing the mattress being inflated from an
initial
deflated state to a fully inflated state by a first sequence of deflating and
inflating
pulses of the type shown in Figure 20.
Figure 21B is a diagrammatic view similar to that of Figure 21A,
showing the progression of a soliton traveling support force-reduction wave
traveling
in a left-to-right, head-to-foot direction produced on the upper surface of
the air
bladder cells of the mattress resulting from a sequence of deflating and re-
inflating
pressure pulses of the type shown in Figure 20 being input to a series of
individual
laterally disposed air bladder cells of the air mattress beginning at the
left, head-end
of the mattress and ending at the right, foot-end of the air mattress.
Figure 21C is a partly diagrammatic view showing a body support
force-reduction wave produced on the surface of the air mattress of Figure 17
by
introducing a sequence of air pressure pulses of the type shown in Figure 20
to a
series of pairs of adjacent air bladder cells of the air mattress, beginning
at the left,
head-end of the air mattress and ending at the right, foot-end of the air
mattress.
Figure 21D is a view showing a downward, head-to-foot body support
force-production wave produced on the surface of the air mattress of Figure 17
in
which odd number air bladder cells 1, 3, . . . through 19 are deflated and re-
inflated
in a first soliton force-reduction wave, and even number air bladder cells 2,
4, . . .
through 20 are deflated and re-inflated in a second soliton body support force-
reduction wave.
Figure 21E is a view similar to Figure 21B but showing a soliton body
support force wave traveling in a toe-to-head direction produced on the
surface of
the air mattress by sequentially deflating and re-inflating air bladder cells
by
pressure pulses beginning at the foot-end of the air mattress, and ending at
the
head-end of the air mattress.
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Figure 21F is a view similar to Figure 21A, showing upwardly and
downwardly soliton traveling body support force waves being produced on the
surface of the air mattress by simultaneously introducing upwardly and
downwardly
traveling soliton waves of air pressure deflation/re-inflation pulses into the
air
.. bladder cells of the air mattress.
Figure 22 is a diagram showing plots of pressure versus time for
deflation/re-inflation cycles of a series of air bladder cells of the
traveling wave air
mattress of Figure 12.
Figure 23 is a diagrammatic view showing deflation pressure versus
time curves of an air bladder cell loaded with different body weights.
Figure 24 is a timing diagram showing a sequence of negative
pressure pulses applied to a sequence of air bladder cells of the air mattress
of
Figures 12 and 1-8 13, in which certain individual air bladder cells that have
been
determined during a previous soliton traveling wave pulse sequence to have
been
subjected to weight load forces below a pre-determined minimum value are
omitted
from the sequence of air bladder cells to which negative air pressure pulses
are
applied, thus decreasing the time intervals between which air bladder cells
that
support pre-determined minimum weight loads are deflated and re-inflated.
Figure 25 is a diagrammatic view of a first modification of the pressure
pulse generator component of the apparatus shown in Figure 13.
Figure 26 is a diagrammatic view of a second modification of the
pressure pulse generator component of the apparatus shown in Figure 13.
Figure 27 is a diagrammatic view of a third modification of the
pressure pulse generator component of the apparatus in Figure 13.
Figure 28 is a simplified upper plan view of a modification of the air
mattress of Figure 2A, which has concentric oval ring-shaped air bladder
cells.
Figure 29 is an upper plan view of a modification of the air mattress of
Figure 28, in which air bladder cells of the array are segmented into
quadrants.
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Figure 30 is a simplified upper plan view of another modification of the
air mattress of Figure 2A, which has concentric circular ring-shaped air
bladder
cells.
Figure 31 is an upper plan view of a modification of the air mattress of
Figure 30, in which air bladder cells of the array are segmented into
quadrants.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figure 1 is a perspective, partly diagrammatic view of a basic
embodiment 10 of a soliton traveling wave air mattress apparatus according to
the
present invention. The apparatus includes an air mattress 20 and a mattress
inflation control apparatus 27. As shown in Figure 1, mattress 20 has in upper
plan
view an outline shape similar to that of a typical hospital mattress, i.e., a
longitudinally elongated rectangle having a length of about 80 inches and a
width of
about 30 to 36 inches. However, the exact dimensions and shape of mattress 20
are not critical, and may differ from the example given.
As shown in Figure 1, mattress 20 has a generally flat rectangular
base panel 21 which may be made of a sheet of a durable flexible plastic
material
such as polyurethane or polyvinyl. Base panel 21 has protruding upwards
therefrom a longitudinally arranged series of laterally elongated, rectangular
plan
view air bladder cells 22. As shown in Figure 1, each air bladder cell 22
extends
from the left-hand longitudinally disposed edge 23 to the right-hand edge 24
of
mattress 20. As is also shown in Figure 1, when air bladder cells 22 are
inflated,
e.g., to a pressure of about 1 psi gauge, the cells have in a vertical
longitudinal
sectional view generally the shape of a laterally elongated semi-cylinder
which has
an arcuately curved, convex upper semi-cylindrical surface 25 that extends
upwards
from base panel 21.
Although the transverse cross-sectional shape and size of air bladder
cells 22 is not critical, a typical size and shape for use in a 80 inch X 36
inch
mattress having 6 laterally disposed air cells would be a semi-cylinder having
a
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base diameter of about 13 inches and a length of about 36 inches, as shown in
Figures 1 and 2A.
Confronting laterally disposed edges 26 of the air bladder cells 22 may
contact each other, or as shown in Figures 1 and 2A, edges 26 may optionally
be
spaced longitudinally apart a short distance, e.g., 1 inch.
Referring to Figure 1, it may be seen that traveling wave air mattress
apparatus 10 includes a mattress inflation control apparatus 27 for inflating
and
deflating air bladder cells 22 to individual pressure levels which provide
comfortable
support for a person supported by mattress 20. Apparatus 10 also includes a
wave
generator apparatus 44 for varying air pressure in inflatable air bladder
cells 22 in a
manner which results in a soliton traveling wave of support-force to propagate
on
the upper surface 28 of the mattress formed by the upper surfaces 25 of air
bladder
cells 22. Preferably mattress 20 is enclosed by a soft fabric mattress cover,
and an
optional thin layer of foam rubber between the upper surface of air bladder
cells 22
and an inside surface of the mattress cover.
According to the invention, wave generator apparatus 44 is used to
produce a soliton traveling wave of support force for the body of a person
supported
on the upper surface 28 of mattress 20 by sequentially varying the air
pressure in
selected paths of individual air bladder cells 22, for example from the head-
end to
the foot-end of the mattress, in predetermined time sequences.
As shown in Figure 1, mattress inflation level control apparatus 27
includes a source of pressurized air 30, which is preferably an air compressor
but
may optionally be a tank containing a pressurized gas such as air or nitrogen.
Air
pressure source 30, which is preferably a compressor driven by an electric
motor
55, has an outlet port 31 connected through an outlet tube 32 to the inlet
port 33 of
a selector manifold 34. Selector manifold 34 has multiple outlet ports 35,
e.g., six
outlet ports 35-1, 35-2, 35-3, 35-4, 35-5 and 35-6, which are individually
connected
through tubes to the inlet ports 36-1 through 36-6 of a group of cell selector
valves
37-1 through 37-6.
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Each cell selector valve 37, which may be a simple on/off gate valve,
has an outlet port 38 which is connected to a first, e.g., upper inlet tube
port 39 of a
Y-tube coupler 40. Each Y-tube coupler 40 has a second, lower inlet tube port
41
and an outlet tube port 42 which is connected to an inflation port 43 of an
individual
air bladder cell 22. Thus for example, outlet tube port 42-1 of Y-tube coupler
40-1
is connected with air pressure-tight fittings to air inlet port 43-1 of the
first, head-end
air bladder cell 22-1 of traveling wave air mattress 20, and so forth.
As will be explained in further detail below, each cell inflation selector
valve 37 is controlled by electrical signals issued by an electronic control
module 51
to inflate and deflate individual air bladder cells 22 to quiescent values
which
provide comfortable support for a person reclining on mattress 20.
Referring still to Figure 1, it may be seen that wave generator
apparatus 44 includes a pressure pulse generator 45 for creating negative and
optionally positive pulses of air pressure in an outlet port 46 which are
conducted to
second, lower inlet port tubes 41 of Y-tube couplers 40. The output port 46 of
pressure pulse generator 45 communicates with a source of pressurized air,
such
as a closed chamber part of a cylinder located on a side of a piston or
diaphragm
which is longitudinally movable in the cylinder in response to forces exerted
on the
piston by a linear actuator.
Wave generator apparatus 44 includes a wave generator controller
44A for issuing electrical command signals to pressure pulse generator 45 and
other components of the wave generator apparatus. Wave generator controller
44A
is preferably a computer, microprocessor, or programmable logic controller
(PLC),
and preferably communicates with or is optionally replaced by a computer 52 of
inflation control apparatus 27.
The magnitude of the negative air pulses need not be any greater than
the maximum intended inflation pressure of any air bladder cell 22. For
example, if
the intended maximum inflation pressure of any of air bladder cells 22-1
through 22-
6 is 1 psi, the negative pulse-generating capability of pressure pulse
generator 45
¨ 16 -
CA 2939545 2018-01-19
should be sufficient to draw all of the air from an air bladder cell 22, e.g.,
about 1.38
cubic feet, within a pre-determined maximum time limit, e.g., 10 seconds. In
actuality, the exhaustion rate of pressure pulse generator 45 may be less,
since
some modes of operation of the invention envision only a fractional reduction
of the
pressure in an air bladder cell 22 from a quiescent value, e.g., one-half.
According to the invention, after a negative pressure pulse has been
applied to an air bladder cell 22, the air pressure in that cell may be
changed to a
quiescent or bias valve different than pressure at the beginning of the pulse,
but is
typically restored to the original bias pressure valve. In either case, a
single
pressure pulse generator 45 within wave generator 44 may be used in
conjunction
with pulse selector valve array 47 to route negative or positive pulses of air
pressure
to selected air bladder cells 22. Thus, as shown in Figures 1 and 2, pressure
pulse
generator 45 has a single outlet port 46 which is connected through a manifold
48
and pressure pulse selector valves 49 of valve array 47 to second, lower inlet
port
tubes 41 of selectable Y-tube couplers 40. Each pulse selector valve 49, which
may
be a simple on/off gate valve, is controlled by electrical signals issued by
wave
generator controller 44A.
Referring to Figure 1, it may be seen that mattress inflation control
apparatus 27 includes an electronic control module 51 for adjusting the static
or
quiescent inflation pressure levels of air bladder cells 22 to values which
provide
comfortable support to a person lying on the upper surface 28 of air mattress
20,
and for controlling functions of wave generator 44.
As shown in Figure 1, electronic control module 51 preferably includes
a computer 52 or a similar programmable electronic component such as a
microprocessor or programmable logic controller (PLC) which emits through an
interface module 53 command signals for actuating various components of the
apparatus 27, such as compressor 30, cell inflation selector valves 37 and
optionally
pulse selector valves 49. Computer 52 may also receives through interface
module
¨ 17 -
CA 2939545 2018-01-19
53 various feedback signals such as valve configuration and compressor outlet
pressure from a pressure transducer 54, etc.
Depending upon whether mattress system 10 is to be configured as a
relatively inexpensive, relaxation-inducing system, or a precision therapeutic
system
for use in hospitals and similar locations, the system 10 may include less or
more
complexity and cost-increasing components. For example, while a low-cost
soliton
traveling wave mattress 20 intended for recreational or relaxation purposes
according to the present invention would not require body support-force
sensors,
embodiments of the invention intended for use in hospital environments would
desirably include a force sensor array that used at least one force sensor
associated with each air bladder cell of the mattress, to monitor reaction
support
forces exerted by the air bladder cells on the body of a patient.
Figure 2B illustrates a modification 10B of the traveling wave air
mattress 10 according to the present invention. As shown in Figure 2B, each of
the
air bladder cells 22B of modified air mattress 20B has in addition to inlet
port 43 a
second inlet port 43B for connection directly to a separate pulse selector
valve 49.
This construction eliminates a requirement for Y-tube couplers 40, since each
cell
pulse selector valve 37 may be connected directly to a separate bladder cell
inflation port 43B. However, the embodiment which employs Y-couplers as shown
.. in Figures 1 and 2A is preferred, because it minimizes the number of tubes
connected to mattress 20.
Figure 3A is a timing diagram showing a typical pattern of variation of
air pressure in individual transverse rows of air bladder cells 22 of the
basic,
relaxational embodiment of soliton traveling wave air mattress system 10 shown
in
Figures 1 and 2A.
Referring to Figure 3A, mattress inflation control apparatus 27 is first
directed by computer 52 to switch on electrical power to drive motor 55 of air
compressor 30. By employing command signals issued from computer 52 through
interface module 53t0 air bladder cell selector valves 37, individual air
bladder cells
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22-1, 22-2, 22-3, 22-4, 22-5 and 22-6 may be inflated to pre-determined air
pressure values monitored by compressor pressure transducer 54. As shown in
Figure 7B, the initial quiescent or bias values of pressure to which
individual air
bladder cells 22 are inflated need not all be the same.
After the individual air bladder cells 22-1 through 22-6 have been inflated
to pre-determined quiescent values, command signals may be initiated by
computer 52
and issued through interface module 53 and a wave generator controller 44A to
initiate
operation of wave generator 44. For example, a first step in the operation of
wave
generator 44 would be to actuate a first pressure pulse selector valve 49 of
pressure
pulse generator 45 to thus provide an air flow path between outlet port 46 of
pressure
pulse generator 45 through lower inlet port tube 41-1 of Y-tube coupler 40-1
to air inlet
port 43-1 of first air bladder cell 22-1.
Next, as shown in line 1 of Figure 3A, pressure pulse generator 45 is
powered on at a time T1 in response to a command signal from computer 52. As
may be understood by referring to Figure 10, applying power to pressure pulse
generator 45 causes a solenoid, pneumatic actuator cylinder or stepper motor-
driven linear actuator to move a diaphragm or piston 183 in a closed cylinder
180
which has on a first active side 188 of the piston 183 a port 146 connected
through
a pulse selector valve 215 of pulse selector valve array 47 to the second,
lower inlet
port tube 41-1 of Y-junction coupler 40-1 connected to inflation port 43-1 of
air
bladder cell 22-1. Pressure pulse generator 45 may also have located on a
second,
down-stroke side 181 of piston 183 a second, storage chamber 61, which may be
optionally connected through air-tight fittings and an optional valve to a
pneumatic
accumulator 62.
As shown in Figure 3A, a first air pressure pulse 63-1 emitted by
pressure pulse generator 45 and conducted to a first air bladder cell 22-1 has
generally an amplitude which varies as a function of time as the negative half
of a
sine wave. However, the shape of air pressure pulse 63 may optionally be
varied
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under computer control to approximate that of a rectangle, trapezoid,
triangle, or
other such shape.
The magnitude of air pressure pulse 63 is variable under computer
control to a desired value, but typically would be about half or less than the
maximum quiescent or bias pressure level in a given air bladder cell or group
of air
bladder cells. For example, for a quiescent air pressure level of 1 psi in a
cell 22 of
mattress 20, the amplitude of air pressure pulse 63 would typically be about
0.5 psi
or less.
As shown in Figure 3A, first air pressure pulse 63-1 is a negative-
going pulse that temporarily reduces the air pressure in air bladder cell 22-
1. It is
envisioned that for use of mattress 20 in hospital beds or other such
therapeutic
applications, the pulse of air pressure produced by pressure pulse generator
45
would typically be negative, to thus temporarily reduce the reaction force
exerted on
a patient's body by a particular air bladder cell 22 or a group of air bladder
cells 22.
However, as shown in Figure 3B, the pulse generator 45 can be configured and
commanded to alternatively produce positive-going pressure pulses 64, for
applications such as relaxational uses of mattress 20.
The period of pulse 63 may be adjusted to any suitable value under
computer control. Thus, the time interval between the beginning, T1 and the
end, T2
of pressure pulse 63 shown in line 1 of Figure 3A can be any desired value,
e.g.,
several seconds to several minutes or longer.
Referring now to the graph in line 2 of Figure 3A, it may be seen that
pulse generator 45 is used to apply a second air pressure pulse 63-2 in a
sequence
of air pressure pulses to a second air bladder cell 22-2 at a programable time
T3.
Beginning time T3 of second pulse 63-2 may be coincident with the end of pulse
63-
1, or delayed to occur at any desired programmable time period later than T2,
e.g.,
1 second, several seconds, or longer. In exactly the same manner, successive
air
pressure pulses 63-3, 63-4, 63-5, and 63-6 may be applied to air bladder cells
22-3,
¨ 20 -
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22-4, 22-5 and 22-6, which cells are located progressively further towards the
foot-
end of air mattress 20 from the head-end air bladder cell 22-1.
As shown in graphs in lines 1-6 of Figure 3A, a negative pressure
wave is produced in a continuous sequence of air bladder cells 22-1 through 22-
6 to
thus produce a soliton traveling wave of reduction in support force for the
body of a
person supported by air mattress 20. As may be understood by referring to
Figure
2A, air bladder cells 22-1 through 22-6 of air mattress 20 span a first
(lateral) area
dimension of mattress 20 and the soliton traveling wave of body support force
reduction travels in a direction parallel to a second (longitudinal) area
dimension of
the mattress. However, it should be understood that characteristics of the
traveling
pressure wave produced by pressure pulse generator 45 of pressure wave
generator 44 and hence characteristics of soliton traveling body force support
waves may readily be modified in real time by suitably programming computer
52.
For example, referring to Figures 2A and 9, the traveling pressure wave may be
programmed to skip over selected air bladder cells, such as even cells 22-2,
22-4,
by not applying negative pressure pulses to those cells. In fact, apparatus 10
may
be programmed to produce sequences of air pressure pulses which travel in any
arbitrary path between air bladder cells 22.
As may be readily understood by viewing Figure 3B, the pressure
pulses produced by pressure pulse generator 45 may optionally be positive-
going
(64-1 through 64-6) rather than negative-going, provided the quiescent
pressure
levels of air bladder cells 22 are initially adjusted to values less than
maximum
inflation levels.
Also, pressure wave generator 44 may optionally be directed by
computer 52 to produce overlapping pressure pulses, parts of which are applied
simultaneously to more than two cells or zones of cells to thus produce an
overlapping soliton body support-force wave. For example, referring to Figure
3A,
the initiation time T3 of a of second air pressure pulse 63-2 may occur
between
beginning and ending times Ti and T2 of first air pressure pulse 63-1, to thus
- 21 -
CA 2939545 2018-01-19
produce a composite soliton traveling support wave pulse which begins at Ti
and
ends at T4, and is longer than the individual pulses shown in Figure 3A.
As shown by the dashed lines in Figures 3A and 3B, the pulse
generator 45 may be programmed to cause some or all of the air bladder cells
22
that have received a pulse of air pressure variation to retain the pressure
level in the
cell at its maximum changed value, or at a value intermediate between the
initial
quiescent level and the maximum changed level.
Pressure wave generator 44 may also be directed by computer 52 to
produce two or more traveling support force waves which travel simultaneously
on
the upper surface 28 of mattress 20. Thus, for example, by programming
computer
52 to direct wave generator 44 to sequentially apply air pressure pulses to
longitudinally descending and ascending pairs of air bladder cells, a first
soliton
traveling wave of support force may be launched on upper surface 28 an air
mattress
20, which travels from the head-end to the foot-end of the mattress, and a
second
soliton traveling wave of support force launched simultaneously, which travels
from
the foot-end to the head-end of the mattress. The foregoing pair of
simultaneous
traveling soliton support waves may be produced by simultaneously applying
pulses
of air pressure to the following pairs of cells; (22-1 and 22-6), (22-2 and 22-
5), (22-3
and 22-4), (22-3 and 22-4), (22-2 and 22-5), and (22-1 and 22-6).
Figure 4 illustrates a second modification 20C of air mattress 20 shown
in Figures 1 and 2A, which has a series of six longitudinally arranged,
transversely
disposed rows, each having 2 side-by-side air bladder cells 22C, for a total
of 12 air
bladder cells.
Figure 5 illustrates another modification 20D of air mattress 20 shown
in Figures 1 and 2A, which has six transversely disposed rows of 4 side-by-
side air
bladder cells 22D, for a total of 24 air bladder cells.
As discussed above, the soliton traveling wave air mattress apparatus
according to the present invention may be programmed to launch pairs of
soliton
support force waves which travel simultaneously in opposite directions on the
upper
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surface of the air mattress. From this discussion, it will be readily
understood that
pressure wave generator 44 may be directed by computer 52 to produce laterally
moving soliton traveling support force waves on the surface of an air mattress
having multiple columns of air bladder cells, such as the mattresses shown in
Figures 4 and 5. Moreover, it will be readily understood that according to the
present invention, two or more traveling soliton support waves may be
simultaneously launched on the mattresses having multiple columns, and these
waves can include simultaneously existing pairs of longitudinally traveling
waves,
laterally traveling waves, or combinations of simultaneous longitudinally and
laterally
traveling waves.
As shown in Figure 1, wave generator apparatus 44 may be used as
an accessory with an existing air mattress apparatus which includes a multi-
cell air
mattress 20 and an associated inflation control apparatus 27, by
interconnecting the
wave generator apparatus to the inflation control apparatus using Y-couplers
40. In
this accessorized configuration, computer 51 of inflation controls module 51
can
provide a signal to wave generator controller 44A indicating when adjustment
of
quiescent air pressures in air bladder cells 22 has been achieved by the
inflation
control apparatus 27, whereupon pulse pressure sequences causing soliton
traveling wave support force waves may be initiated by pressure pulse
generator 45.
Figures 6 and 7A illustrate an embodiment 110 of a soliton traveling
wave air mattress according to the present invention, which is a modification
of the
basic embodiment 10 and is suitable for use in hospitals, nursing homes and
similar
facilities.
As shown in Figures 6 and 7A, modified soliton traveling wave
apparatus 110 includes a mattress 120 which may be similar in construction to
the
basic mattress embodiment 20 shown in Figure 1 and described above. For ease
of
explanation, the mattress shown in Figures 6 and 7 is shown to have 6
transversely
disposed, non-subdivided air bladder cells. However, mattress 120 actually
includes a rectangular matrix of air bladder cells 122 as shown in Figures 4
and 5,
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rather then a single column of transversely disposed rows of air bladder
cells, which
enables air pressure and hence body support forces to vary only in a single,
longitudinal head-to-toe direction.
According to the invention, air mattress 120 intended for use in
hospitals would have as shown in Figure 4 at least two and preferably three,
four, or
more separate laterally disposed columnar zones of air bladder cells, as shown
in
Figure 5.
As shown in Figure 5, 6 and 7A, an example air mattress 120 has six
different transversely disposed, longitudinally ordered zones which span the
head-
to-toe length of the mattress. Each of the six transversely disposed rows of
air
bladder cells 122 is partitioned into four rectangular air bladder cells, each
of which
is hermetically isolated from all other air bladder cells.
Thus, in the example embodiment of air mattress 120 shown in
Figures 5 and 6, there is a rectangular matrix array of 24 rectangularly-
shaped air
bladder cells 122-1 through 122-24, each of which is hermetically isolated
from all of
the other air bladder cells in the array. This construction enables each of
the air
bladder cells 122-1 through 122-24 to be separately inflated and deflated to
individually adjustable bias or quiescent levels.
Apparatus 110 also has an inflation control apparatus 127 and a
pressure wave generator 144 that enables air pressure pulses to be applied to
individual air bladder cells 122 or groups of cells, in any desired
combination and
sequence.
Preferably, as shown in Figure 6, traveling wave air mattress 110
includes a force sensor array 170. Force sensor array 170 is comprised of a
group
of individual flexible surface reaction force sensors 171-1 through 171-24,
each of
which is fastened in vertical alignment with a separate one of air bladder
cells 122-1
through 122-24. Each sensor 171-1 through 171-24 is a two-terminal device
which
has a first output terminal 172-1 - 172-24 that is connected to an individual
lead wire
173-1 through 173-24. Each sensor 171 also has a second output terminal 174-1 -
¨ 24 -
CA 2939545 2018-01-19
174-24 which is connected to an individual lead wire 175-1 though 175-24.
Alternatively, the sensors 171-1 through 171-24 may be interconnected in an X-
Y
matrix, using 6 row-connector lead wires 176-1 through 176-6, and 4 column-
connector lead wires 177-1 through 177-4. In either arrangement, the lead
wires
are used to connect sensors 171 to a sensor interface module 176 of inflation
control apparatus 127.
Sensors 171-1 through 171-24 of sensor array 170 are used to
monitor reaction support forces exerted on various parts of the body of a
person
supported by air bladder cells 122-1 through 122-24 of traveling wave air
mattress
120.
Monitoring of reaction support forces exerted on a patient's body is
performed when a patient first lies down on mattress 120, and the air bladder
cells
122-1 through 122-24 are inflated to quiescent or bias values which provide
comfortable support to the patient; ideally by reducing reaction support
forces which
are above a certain desired maximum by reducing air pressure in some cells and
increasing air pressure in other cells.
At a pre-determined time after initial adjustment of quiescent air
pressure levels in air bladder cells 122-1 through 122-24, computer 152 of
inflation
control apparatus 127 generates pre-determined patterns of pressure pulses
which
when applied to the air bladder cells, result in production of soliton
traveling waves
of patient body-support forces that travel on the upper surface 28 of the
mattress.
The magnitude, shape, timing and other characteristics of air pressure
pulses generated by pressure pulse generator 145 may in general be similar to
those of the pulses described above for the basic embodiment 10 of the
traveling
wave air mattress. However, since the air bladder cells 122-1 through 122-24
of air
mattress 120 have distinct laterally separated as well as longitudinally
separated
locations, traveling pressure waves and hence traveling soliton body support-
force
variation waves can be directed laterally and obliquely as well as
longitudinally on
the surface of the mattress. Moreover, as will be explained in detail below,
surface
¨ 25 ¨
CA 2939545 2018-01-19
reaction force sensor array 170 of air mattress apparatus 110 may be used to
calculate in real time paths for reaction force support waves which can
minimize
long-term large-magnitude reaction forces which might be exerted on a
patient's
body, and thus further aid in preventing formation of decubitus sores.
An example of calculating a beneficial path of a traveling pressure
support wave in response to reaction force measurements using sensor array 170
may be understood by referring to Figure 8 and Table 1.
Figure 8 is a diagrammatic upper plan view of a two-column by six row
modification or part of air mattress 120. As shown in Figure 5, there are
twelve air
bladder cells 122-1 through 122-12, each of which has attached to and in
vertical
alignment therewith a separate one of an array of surface reaction force
sensors
171-1 through 171-12, which are used to produce a pressure map of surface
reaction forces exerted on a patient's body. Hypothetical example values of
measured patient body support reaction forces are listed in Table 1. As shown
in
Figure 8, a surface reaction force gradient vector is constructed using the
pressure/force map values of Table 1. The tail end of the gradient vector is
located
in air bladder cell number 122-1, since the highest surface reaction force,
1.5
kilopascals (kPa) was measured by sensor 171-1 in cell 122-1.
The second highest reaction force of 1.4 kPa was measured in cell
number 122-4, so the first segment of the gradient vector V is directed from
cell
122-1 to cell 122-4.
The third highest reaction force of 1.3 kPa was measured in cell
number 122-7, so the second segment of gradient vector V is directed from cell
122-4 to cell 122-7.
The fourth highest reaction force of 1.1 kPa was measured in cell
number 122-12, so the third segment of gradient force vector V is directed
from cell
122-7 to cell 122-12.
According to the invention the segmented gradient force vector V
measured and calculated as above is used to direct computer 52 to generate a
¨26 -
CA 2939545 2018-01-19
pressure reduction wave which is applied consecutively to air bladder cells
122-1,
122-4, 122-7 and 122-12, thus producing a soliton traveling surface support
reaction
force reduction wave which follows the measured reaction force gradient.
TABLE 1
CELL NUMBER MAX REACTION FORCE, kPa
1 1.5
2 1.0
3 0.9
4 1.4
5 0.8
6 0.8
7 1.3
8 0.9
9 0.9
0.9
11 1.0
12 1.1
5
Figure 9 illustrates an example of a pressure pulse wave 163 which is
applied by wave generator apparatus 144 to traveling wave air mattress 120
along
the path of a gradient vector V calculated by computer 152 from reaction
forces
exerted on a patient's body and measured by sensors 171.
10 As shown in Figure 9, traveling pressure pulse ware 163 is
created by
applying a first pulse 163A of negative pressure created by pressure pulse
generator 145 to air bladder cell 122-1 between times T1 and T2. At a time T3
following T1 which optionally precedes T2, a second pulse of negative pressure
163B is applied to air bladder 122-4 and continued until 14. In an exactly
- 27 -
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analogous fashion, a third negative air pressure pulse 163C is applied to air
bladder
cell 7 between times T5 and T6, and a fourth and final negative air pressure
pulse
163D is applied to air bladder cell 122-12 between times T7 and T8.
As can readily be envisioned by referring to Figures 6-9, the sequence
of four negative air pressure pulses 163A, 163B, 1630 and 163D applied to air
bladder cells 122-1, 122-4, 122-7 and 122-12, respectively, creates a soliton
traveling wave of patient body support-force reduction. As described above,
the air
bladder cell air pressure reduction soliton traveling wave is directed to
follow the
patient reaction support force gradient vector. Accordingly, by temporarily
reducing
the inflation pressure of air bladder cells which are exerting the greatest
support
force concentrations on a patient's body, these forces, which could cause
decubitus
sores if left unabated for long periods of time, will be substantially reduced
for time
periods proportional to the product of the length of pressure reduction pulse
163
and the number of times per day that the traveling pressure pulse wave cycle
is
repeated.
In general, during the generation of a soliton traveling body support-
force variation wave by a sequence of pressure reduction pulses applied to air
bladder cells 122, pressures exerted on a patient's body by other air bladder
cells,
in contrast to total support forces, may increase, since the total support-
forces are
proportional to the fixed weight of a patient supported by the mattress and
hence
are constant over time intervals. Moreover, the soliton traveling wave of
support-
force reduction, or patient movement may shift the distribution of body
reaction
support-forces at the end of a soliton traveling wave cycle. For the foregoing
reasons, sensor array 170 would desirably be used to continuously monitor body
support reaction forces over the entire surface of mattress 120, to thus
determine
whether an initially measured force gradient has shifted location, whereupon
successive cycles of soliton traveling support force reduction may be
propagated
along the paths of newly determined body support -force gradient vectors.
¨ 28 -
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Figure 10 is a partly diagrammatic view of pressure wave generator
144, which may be substantially similar in construction to pressure wave
generator
44.
As shown in Figure 10, pressure wave generator 144 includes a
pressure pulse generator 145 that has a longitudinally elongated, hollow
circular
cross-section cylinder 180 which has disposed through its length a coaxial
cylindrical inner bore 181. Bore 181 is sealed at a first, head-end of
cylinder 180 by
a transversely disposed circular disk-shaped cylinder head 182, which has
disposed
through its thickness dimension an air passageway which comprises an outlet
port
.. 146.
As shown in Figure 10, bore 181 of pressure wave generator cylinder
180 has therewithin a circular disk-shaped piston 183. Piston 183 has an outer
wall
surface 184 which longitudinally slidably contacts in a hermetic seal the
inner
cylindrical wall surface 185 of cylinder 180.
As shown in Figure 10, that side of cylinder bore 181 located between
a head-end transverse surface 186 of piston 183 and the inner surface 187 of
cylinder head 182 forms a cylindrically-shaped, head-space active chamber 188
which is positively pressurizable by longitudinal motion of the piston 183
towards the
cylinder head 182, and negatively pressurizable by longitudinal motion of the
piston
.. towards the transverse base or end wall 189 of cylinder 180.
As shown in Figure 10, piston 183 of pressure pulse generator 145
has extending longitudinally away from base end surface 190 of the piston a
tubular
drive shaft 191 which extends longitudinally outwards of lower transverse
annular
base or end wall 189 of cylinder 180.
Pressure pulse generator 145 includes a force actuator 192 to drive
piston drive shaft 191 and piston 183 longitudinally rearward within cylinder
180 to
thereby produce within active chamber 188 of the cylinder a negative pressure
pulse. Force actuator 192 also has the capability of moving piston drive shaft
191
forward within bore 181 of cylinder 180 to thus restore piston 183 to its
original
¨ 29 -
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longitudinal location within bore 181 of cylinder 180. Thus, if piston drive
shaft 191
is pivotably joined to piston 183, force actuator 192 may consist of a rotary
motor
coupled to the outer end 193 of piston drive shaft 191 by an eccentric coupler
such
as a crank. However, in a preferred embodiment of pressure pulse generator
144,
force actuator 192 has a different design and construction which provides more
control of the characteristics of pressure pulses produced by movement of
piston
183 in cylinder 180.
Thus, as shown in Figure 10, piston drive shaft 191 of pressure pulse
generator 145 has a hollow tubular construction which includes an elongated
circular cross-section bore 194 that extends through the outer, rear
transverse
annular end wall 195 of the piston drive shaft. The piston drive shaft 191 has
fixed
within the lower end of bore 194 thereof a cylindrically-shaped follower or
jack screw
nut 195 which has through its thickness dimension a coaxial threaded bore 196.
Bore 196 of follower or jack screw nut 195 receives thread ingly therein an
elongated
threaded lead-screw or jack-screw 197 which is rotatably driven by a stepper
motor
198.
Stepper motor 198 receives drive signals from a stepper motor drive
electronic module 199 of a wave generator controller 144A which receives
command signals from computer 152. This construction of the pressure wave
force
actuator facilitates repositioning the rest position of piston 183 within
cylinder bore
181 to a rearward or retracted position, so that the piston drive shaft 191
and piston
183 can be extended forward to produce positive pressure pulses in outlet port
146,
followed at the end of a pulse by retraction to a rearward quiescent position
which
reduces pressure in an air bladder cell to its quiescent pressure value.
Preferably, as shown in Figure 10, pressure pulse generator 145
includes optional components which enable it to introduce negative or positive
air
pressure pulses into individually selectable air bladder cells 122 that may be
initially
inflated to different quiescent pressures, and restore the inflation level to
the initial
quiescent pressure level at the end of a pressure pulse. Thus, as shown in
Figure
- 30 -
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10, outlet port 146 of pressure pulse generator 145 is connected through a
cylinder
isolation valve 200 through a tubular connector fitting 201 to the inlet port
202 of a
pulse selector valve array manifold 203. Cylinder isolation valve 200 has a
value
actuator control input terminal lead 215 which is connected to a command
signal
output terminal of wave generator controller 144A.
The pressure pulse generator 145 includes a cell pressure sampling
pressure transducer 204 which has a pressure probe 205 that communicates with
a
hollow cylindrical bore space 206 of tubular fitting 201 that is located
between pulse
selector valve array manifold 203 and cylinder isolation valve 200. Cell
pressure
transducer 204 has an output terminal lead 207 which is connected to wave
generator controller 144A, which has a command signal output terminal that is
connected to stepper motor electronic drive module 199. Wave generator
controller
144A. is also connected to a signal input interface port of computer 152, to
provide
coordination between the computer and wave generator controller.
As shown in Figure 10, pressure pulse generator 145 also has a pulse
generator cylinder pressure sampling transducer 208 which has a pressure probe
209 that communicates with active chamber head space 188 of bore 181 of
cylinder
180. Cylinder pressure sampling transducer 208 has an output terminal lead 210
which is connected to a signal input interface port of wave generator
controller
144A.
As is also shown in Figure 10, pressure pulse generator 145 has a
cylinder bleed valve 211 which has an inlet port 212 that communicates with
active
chamber 188 of cylinder 181, an outlet port 213 which communicates with the
atmosphere, and an electrical valve actuation control input terminal lead 214
which
is connected to a command signal output interface terminal of wave generator
controller 144A.
Optionally, as shown in Figure 10, pulse generator may include a
manifold isolation valve 216 between tubular fitting 201 and pulse selector
manifold
203.
¨ 31 -
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Operation of pressure pulse generator 145 constructed and configured
as shown in Figure 10 is as follows.
First, computer 152 issues a command which is transmitted through
wave generator controller 144A to open a selected one of pulse selector valves
149
that is connected to a selected air bladder cell 122 which is to receive a
pulse of air
pressure, and to open optional manifold isolation valve 216.
Second, cell pressure sampling transducer 204 is used to measure the
value of quiescent air pressure in the selected air bladder cell 122.
Third, cylinder air pressure sampling transducer 208 is used to
measure cylinder air pressure in active chamber 188 of cylinder 180.
Fourth, the difference in air pressures measured by air bladder cell
pressure transducer 204, and cylinder air pressure measured by cylinder air
pressure transducer 208 is computed by wave generator controller 144A or
computer 152. If the measured air pressure in cylinder active chamber 188 is
less
than the quiescent air pressure in a selected air bladder cell 122, a command
signal
is issued to stepper motor controller 199 which causes piston drive shaft 191
and
piston 183 to be extended forward within cylinder 180 to increase air pressure
in
active chamber 188 of the cylinder until it is equal to the quiescent air
pressure in
the selected air bladder cell 122.
For example, piston 183 may be extended forward in cylinder bore 181
from position 3 to position 2 in Figure 10. This longitudinal position of
piston 183,
where the pressures in cylinder 180 and a selected air bladder cell 122 are
equalized, is defined as a first home position for the piston, prior to
production of a
pulse of pressurized by air pressure pulse generator 145, and introduction of
the
pulse of pressurized air into a selected air bladder cell 122. Cylinder bleed
valve
211 may also receive command signals from wave generator controller 144A to
enable air flow between cylinder chamber 188 and the atmosphere, to thus
facilitate
pressure equalization.
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Fifth, as shown in Figure 10, cylinder isolation valve 200 is opened in
response to a command signal issued through waves generator controller 144A by
computer 152, which also causes a command signal to issue to stepper motor
driver
199. If the command signal from computer 152 is to reduce air pressure in a
selected air bladder cell 122 by producing a negative pressure pulse, piston
183 is
retracted to a position such as positions 3, 4 or 5. If the command signal
from
computer 152 is to increase pressure in a selected air bladder cell 122,
piston 183 is
extended forward to a longitudinal location such as position 1 in Figure 10.
In either
case, cylinder isolation valve 200 and optional manifold isolation valve 216
remain
open during the initial movement of piston 183.
Sixth, at a predetermined time at which a pulse of air pressure into an
air bladder cell is to be terminated, piston 183 is commanded to move in a
direction
opposite to its direction at the beginning of an air pressure pulse. For
example, if
the air pressure in a selected air bladder cell is to be restored to the value
which it
had at the beginning of a pressure pulse, piston 183 would be returned to the
initial
home position, such as location 2 in Figure 10. However, if it is desired to
return the
air pressure in a selected air bladder cell 122 to a new quiescent value
different
from an original quiescent value, piston 183 is moved to a different location
at the
end of a pressure-pulse cycle.
Seventh, at a predetermined time period after piston 183 has ceased
movement at the end of a pressure pulse cycle, pulse selector valve 149,
optional
manifold isolation valve 216, and cylinder isolation valve 200 are closed in
response
to command signals received from wave generator controller 144A.
As shown in Figure 10, the output port of each pulse selector valve
149 is coupled to the inlet port 143 of an air bladder cell 122 through the
input tube
141 and a Y-coupler 140 which also has an input tube 139 which is coupled to
an
inflation control apparatus 127 that is used to initially inflate the air
bladder cells to
initial quiescent pressure values which provide comfortable support to a
patient.
However, pressure pulse generator 145 may optionally be used to inflate and
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deflate air bladder cells 122 to initial quiescent pressure values prior to
initiation of
the seven-step wave generation process described above.
With this optional configuration, pulse selector valves 149 perform a
dual function, initially adjusting quiescent pressure levels in individual air
bladder
cells 122, and subsequently introducing a sequence of pressure pulses into the
air
bladder cells to create a traveling support force wave. Thus, with this
optional
configuration, the requirement for a separate inflation control apparatus 127
and Y-
couplers 140 is eliminated, and each pulse selector valve 149 is connected
directly
to the port 143 of an air bladder cell 122.
The pressure pulse generator 145 of the pressure wave generator 144
described above requires a piston/cylinder displacement volume at least as
large as
the maximum volume of air which is intended to be simultaneously input to or
removed from one or more air bladder cells 22 or 122. Consequently, pressure
pulse generator 145 is ideally suited for use with air mattresses having a
relatively
.. large number e.g., 12 to 24 or more, of relatively small air bladder cells.
However,
for air mattresses which have a relatively small number, e.g., 4 to 6 of
relatively
large air bladder cells, the displacement requirements for single piston
stroke
deflation or inflation of one or more air bladder cells may require that the
displacement volume and hence size of cylinder 180 of air pulse generator be
undesirably large for some applications.
For example, for an air mattresses 20 of the type shown in Figure 1
which has 6 air bladder cells 22 which have a semi-cylindrical shape when
inflated
to a normal bias pressure of 14.7 lbslin2 (101.3 kPascals), i.e., 1
atmosphere, a
diameter of 13 inches and a lateral length of 3 feet, the volume of each air
bladder
cell would be about 1.276 cubic feet. Therefore, the volume of cylinder 180 of
air
pulse generator 185 shown in Figure 10 would need to be 1.276 cubic feet or
larger,
if operation of the pulse generator required complete deflation or re-
inflation of a
single air bladder cell 22 with a single stroke of piston 183 within cylinder
180. An
embodiment of a wave generator of the present invention which is useful for
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creating traveling support force waves in air mattresses having relatively
large air
bladder cells is shown in Figures 11A and 11B.
As shown in Figures 11A and 11B, an embodiment of wave generator
244 useful for deflating and re-inflating air bladder cells 22 of a relatively
large air
mattress 20 of the type shown in Figure 1 has an air pulse generator 245 that
includes an air pump 280 which has a vacuum inlet port 281 and a pressure
output
port 282. An example of a suitable type of air pump 280 for use in the present
application is a linear air pump which uses a magnet moving in response to
time
varying electromagnetic force fields produced by an alternating current to
drive a
piston in a reciprocating motion within a cylinder. Such pumps are described
in
further detail in "Mechanisms And Mechanical Devices Sourcebook." 51h Edition
by
Neil Sclater, McGraw-Hill, New York 2011, page 374.
As can be envisioned by referring to Figures 11A and 11B, when a
piston (not shown) moves inwardly within a cylinder (not shown) of air pump
280 in
response to an attractive electromagnetic force, a negative pressure occurs in
pump
inlet port 281, which may draw air through the inlet port 281 and past an
inlet flapper
valve 284 into the head-space 285 between the piston 286 and the inlet port.
During this first, inlet part of the air pump cycle, negative pressure within
head
space 285 of air pump 280 also draws an outlet flapper valve 288 inwardly to a
closed position which seals off communication between the pump head-space and
outlet port 282.
Conversely, when the piston moves outwardly in response to a
repulsive electromagnetic force, a positive pressure pulse is produced in head
space 285 of cylinder 283. The positive pressure closes input flapper valve
284 and
opens output flapper valve 287, through which a pulse of air at positive
pressure is
expelled through outlet port 282 of the air pump.
From the foregoing description, it can be readily understood that
powering air pump 280 with alternating current at a 60 Hz line frequency
results in
60 pulses per second of negative air pressure occurring in inlet port 281 of
the
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CA 2939545 2018-01-19
pump, and positive pulses of air pressure occurring in outlet port 282 at the
same
frequency but shifted 180 degrees in phase from the negative air pulses at
inlet port
281.
As shown in Figures 11A and 11B, soliton traveling wave generator
244 includes a pressure pulse routing assembly 290 comprised of routing valves
and air conduits which are interconnected between linear air pump 280 of air
pulse
generator 245, and pulse selector valves 249 on pulse selector manifold 246.
Pressure-pulse routing assembly 290 connects negative air pressure inlet port
281
of air pump 280 to a selected air bladder cell 22 during the initial, negative-
going
part of a negative pressure pulse applied to an air bladder cell, and connects
the air
bladder cell to positive pressure at outlet port 282 of the pump during the
final,
positive-going part of a negative pressure pulse.
As is also shown in Figures 11A and 11B, pressure-pulse routing
assembly 290 includes three 2-way or diverter-type valves which are all
similar in
construction and function. Thus, as shown in Figures 11A and 11B, wave
generator
apparatus 244 includes a first, pump inlet router valve 291 which has an
output port
292 that is connected to inlet port 281 of pump 280 by a tubular pressure-
tight tube
293. Pump inlet router valve 291 has a first, upper selector-manifold inlet
port 294
which is connected to a second, selector manifold router valve 311. Selector
manifold router valve 311 is connected to inlet port 246 of manifold 248 by a
tubular
pressure-tight tube 297. Pump inlet router valve 291 also has a second, supply-
air
inlet port 298.
Also shown in Figures 11A and 11B, pump inlet router valve 291 has
an internal valve plate 299 which is pivotably movable by a solenoid actuator
300 in
response to an electrical control signal input to an input terminal 301 of the
actuator,
which is connected by an electrical wire to a first valve control output port
302 of
wave generator controller 244A.
Referring still to Figures 11A and 11B, it may be seen that valve plate
299 has a first pivotable position in which the valve plate is pivoted
counterclockwise
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to block air flow to supply-air inlet port 298, and to permit air flow between
selector
manifold inlet port 294 and outlet port 292 of the valve. In this position,
negative air
pressure pulses at inlet port 281 of pump 280 are transmitted through pump
inlet
router valve 291, through selector manifold router valve 311, and through a
pulse
selector valve 249 of pulse selector manifold 248 to a selected air bladder
cell 22,
thus enabling air to be withdrawn from the air bladder cell through the port
43 of the
air bladder cell, which is connected to the selector valve during the first,
negative
going part of a negative pressure pulse produced by air pump 280.
Since, as pointed out above, the air pump 280 produces a sequence
of pressure pulses at a line frequency rate, e.g., 60 Hz, a negative pressure
pulse
selected by wave generator controller 244A to have a length of 1 second, for
example, will actually consist of 1 second long pulse modulated at 60 Hz,
i.e., a
one-second long train of 60 pulses.
As shown in Figure 11A, air flow from a selected air bladder cell 22
and pulse selector valve 249 is routed through selector manifold router valve
311.
Pulse selector manifold router valve 311 has a common outlet port 312 which is
connected by a hermetically sealed coupling to input port 246 of pulse
selector
manifold 248. Pulse selector manifold router valve has a first, upper outlet
port 313
which is connected to upper inlet port 294 of pump inlet router valve 201 by a
tubular pressure-tight coupler 314. Pulse selector manifold router valve 311
also
has a second, lower outlet port 315.
As shown in Figures 11A and 11B, pulse selector manifold router
valve 311 has an internal valve plate 319 which is pivotably moveable by a
solenoid
actuator 320 in response to an electrical control signal input to an input
terminal 321
of the actuator which is connected by an electrical wire to a second valve
control
output port 322 of wave generator controller 244A.
As shown in Figures 11A and 11B, valve plate 319 has a first pivotable
position in which the valve plate is pivoted clockwise to block air flow
between lower
output pulse selector manifold port 246 and lower port 315 of pulse selector
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manifold router valve 311. As shown in Figure 11A, with valve plate 319 in
this
position, there is an unobstructed air flow path between manifold output port
246,
through valve 311 to input port 294 of pump inlet valve 291, and thence into
inlet
port 281 of pump 280,
Referring to Figure 11A, it may be seen that pulse routing assembly
290 of wave generator 244 includes a third, pump outlet router valve 331 which
has
an inlet port 332 that is connected to outlet port 282 of pump 280 by a
tubular
pressure-tight tube 333. Pump outlet router valve 331 has a first, upper
outlet port
334 which is connected by a tubular pressure-tight tube 335 to the lower inlet
port
315 of pulse selector manifold router valve 311. Pump outlet router valve 331
also
has a second, lower exhaust outlet port 336.
As shown in Figures 11A and 11B, pump outlet router valve 331 has
an internal valve plate 339 which is pivotably moveable by a solenoid actuator
340
in response to an electrical control signal input to an input terminal 341 of
the
actuator, which is connected by an electrical wire to a third valve controller
output
port 342 of wave generator controller 244A.
As also shown in Figures 11A and 11B, valve plate 339 has a first
pivotable position in which the valve plate is pivoted clockwise to block air
flow
between outlet port 282 of pump 280 and lower input port 315 of pulse selector
manifold router valve 311. In this position, there is an unobstructed air flow
path
between pump outlet port 282 and lower outlet port 336 of pump outlet router
valve
331.
As indicated by the arrow-headed lines in Figure 11A, with the three
router valves 291, 311 and 331 configured as shown in Figure 11A and described
above, operation of pump 280 causes air to be withdrawn from a selected air
bladder cell 22 into pump inlet 281 and discharged from pump outlet port 282
through output port 336 of pump outlet router valve 331.
Outlet port 336 of pump outlet router valve 331 may optionally open
directly to the atmosphere. Preferably, however, as shown in Figures 11A and
11B,
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outlet port 336 is connected to a first port 341 of a three-way tubular Y-
junction or T-
junction coupler 340. A second port 342 of coupler 340 is coupled through a
tube
344 to lower input port 298 of pump inlet router valve 291. A third port of
coupler
340 is coupled through a tube 345 to the inlet port 246 of a pneumatic
accumulator
or receiver 347. Thus, as shown in Figure 11A, during the initial, negative-
going half
of a negative air pressure pulse applied to an air bladder cell 22 to withdraw
air and
reduce the inflation pressure of the cell, withdrawn air is routed into
accumulator
347. Optionally, accumulator 347 may consist of one or more separate air
bladder
cells which are similar in construction to the individual air bladder cells 22
of air
mattress 20. The additional air bladder cells which are used as an accumulator
may
be located remotely from the air mattress or optionally at either or both the
foot end
and head end of the mattress.
Figure 11B illustrates valve configuration and resulting air flow paths
directed by wave generator controller 244A during the second half of a
negative
pressure pulse, in which a volume of air is re-introduced into an air bladder
cell 22
to thus partially or fully re-inflate the cell to a new or original quiescent
value of
pressure, respectively.
As may be understood by referring to Figure 11B, a positive-going part
of a pressure pulse applied to an air bladder cell 22 is created by directing
air flow
from outlet port 282 of pump 280 to inlet port 246 of pulse selector manifold
248,
and thence through a selected valve 249 to a selected air bladder cell 22.
Thus, as
shown in Figure 11B, valve plate 339 of pump outlet router valve 331 receives
a
signal from wave generator controller 244A to pivot to a position which allows
air
flow from pump outlet port 282 and through upper outlet port 334 of valve 331,
and
thence through inlet port 315 of pulse selector manifold router valve 311,
through
the port 312 of the manifold router valve, and finally through a selector
valve 249 to
a selected air bladder cell 22.
As shown in Figure 11B, during the positive-going part of an air
pressure pulse to be delivered to an air bladder cell 22, valve plate 319 of
pulse
¨ 39 -
CA 2939545 2018-01-19
selector manifold router valve 311 is positioned by a command signal from wave
generator 244A to block air flow through port 313 of valve 311. As is also
shown in
Figure 11B, during the positive-going part of an air pressure pulse, valve
plate 299
of pump inlet routing valve 291 is positioned by a command signal from wave
generator 244A to block air flow through port 294 of valve 291. In this
position,
there is created an unobstructed air flow path for air which was pressurized
in
accumulator 347 during the negative-going part of an air pressure pulse,
through
pump inlet router valve 291 and thence into inlet port 281 of pump 280.
Referring to Figures 11A and 11B, it may be seen that wave generator
244 preferably includes a pressure transducer 348 which communicates with
inlet
port 246 of pulse selector manifold 248. With valve plate 319 of selector
manifold
router valve 311 in a clockwise, closed position as shown in Figure 11A, and
valve
plate 249 of pump inlet router valve 299 in a clockwise, closed position as
shown in
Figure 11B, opening a selector valve 249 connected to the port 243 of a
selected air
bladder call 222 results in equalization of pressure between the interior
volume of
the selected air bladder cell and the much smaller volume of a space located
between the valve plate 249 and the input port 246 of the pulse selector
manifold.
Probe 349 of pressure transducer 348 communicates with this space and thus
produces at an output terminal 350 of the transducer an electrical signal
which is
proportional to air pressure within a selected air bladder cell 222, which
signal is
conducted by an electrical wire 351 to wave generator controller 244A.
Listed below is a typical sequence of operations of wave generator
244 and configurations of router valves 291, 311 and 331 during the various
steps
of pulse generator 245 in response to electrical control signals issued by
wave
generator controller 244A to effect pre-programmed sequences of pressure pulse
generation which result in soliton traveling support force waves on the
surface of air
mattress 20. Table 2 following the operational sequence summary lists the
configurations of router valves 291, 311 and 331 during the various steps of a
pulse
generation sequence.
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WAVE GENERATOR OPERATION SEQUENCE
1. Initialize System.
2. Receive command to begin wave.
3. Open selector valve 249 to select a first air bladder cell 22.
4. Measure pressure in selected cell via pressure transducer 348 connected
to
inlet port 246 of selector manifold 248.
5. Input pressure measurement value to wave generator controller 244A.
6. Open pump inlet router valve 291.
7. Turn vacuum/pressure pump 280 on to withdraw air from selected cell.
8. Leave pump 280 on until negative pressure-peak measured by transducer
348 and input to controller 244A is achieved.
9. Close pump inlet router valve 291.
10. Shut pump 280 off.
11. Allow time period equal to desired negative peak pressure dwell time
period
to elapse.
12. Open pump outlet router valve 331.
13A. Turn pump on to input air into selected cell 22.
13B. Open selector manifold router valve 311 to input air into selected cell
22.
14. Leave pump on until pressure measured by transducer 348 increases to
original or new desired bias level.
15A. Close selector manifold router valve 311.
15B. Close pump outlet router valve 331.
16. Shut pump off.
.. Repeat steps 3-16 for additional selected air bladder cells in a sequence
required
for a desired wave cycle.
17. Repeat steps 1-16 for each additional wave cycle commanded by wave
generator controller 244A.
¨ 41 -
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TABLE 2
SEQUENCE VALVE 1, VALVE 2, VALVE 3,
STEPS PUMP INLET SELECTOR PUMP
OUTLET
(291) MANIFOLD (331)
(311)
Clockwise (CW),
1-5 CW, Closed CW, Closed
Closed
Counterclockwise
6 -8 (CCW) CW, Closed CW, Closed
Open
9 -11 CW, Closed CW, Closed CW, Closed
12 -14 CCW, Closed CCW, Open CCW, Open
15 -16 CW, Closed CW, Closed CW, Closed
Figures 12-24 illustrate the construction of a third embodiment of a
soliton traveling wave air mattress apparatus 400 according to the present
invention.
As will be explained in detail, soliton traveling wave air mattress 400 has a
modular
construction which facilitates manufacture and use of a range of traveling
wave air
mattress apparatuses having different degrees of complexity, cost, and
features
suitable for use both in preventing the formation of bedsores, and for
relaxation
purposes.
Referring to Figure 12, modular soliton traveling wave air mattress
apparatus 400 may be seen to include a wave generator module 401 and an air
mattress module 402. The air mattress module 402 includes an air mattress 403
comprised of an array of generally semi-cylindrically shaped, individually
inflatable
air bladder cells 404, which are made of air impervious material such as thin
vinyl
plastic sheeting. An example embodiment of mattress 403, which was found
suitable for both health care and relaxational applications, consists of 20
laterally
¨42 -
CA 2939545 2018-01-19
disposed tubes that were arranged in a side-by-side array, each of the tubes
having
a diameter of about 4 inches and a length of about 34 inches. Thus the
mattress
403 had a length of about 80inches and a width of about 34 inches, which is of
a
suitable size for placement on supporting surfaces such as a standard size bed
mattress or a portable air mattress.
As shown in Figure 12, air mattress module 402 includes an air
mattress interface module 405. Air mattress interface module 405 has on an
outlet
side 406 thereof a row of twenty individual outlet ports 407-1 through 407-20
for
pressurized air, which are connected through flexible tubes 408-1 through 408-
20 to
inlet ports 409-1 through 409-20 of air bladder cells 404-1 through 404-20.
As is also shown in Figure 12, wave generator module 401 includes a
wave sequence generator 410 which is connected through an elongated flexible
15-
conductor cable 411 to 15 individual electrical port terminals 412 of an
electrical
interface port side 413 of air mattress interface module 405.
Referring still to Figure 12, it may be seen that wave generator module
401 includes an air pressure pulse generator 414 which has an outlet port 415.
Air
pressure outlet port 415 is connected through a single flexible air tube 416
to an
inlet port 417 located on a side 418 of air mattress interface module 403.
As shown in Figure 12, wave generator module 401 includes a control
electronics module 419 which is connected to wave sequence generator module
410 and air pressure pulse generator 414. Wave generator module 401 also
includes a power supply 420 for converting 115-volt A.C. power input to the
wave
generator module 401 on a power cord 422 terminating in a power plug 421
plugged into a mains power source, into 12-volt D.C. power for operating
control
electronics module 419, pressure pulse generator 414 and wave sequence
generator 410.
In a preferred embodiment of soliton traveling wave apparatus 400,
wave generator module 410 may be located some distance from a bed, portable
mattress, or other support on which air mattress 403 is placed, and connected
to air
¨ 43 -
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mattress module 402 by single flexible cable 411 which contains insulated
conductors operating at an electrical potential of no more than 12 volts D.C.,
and by
a parallel flexible air tube 416. Desirably, air mattress interface module 405
may be
positioned near the foot-end of air mattress 403, and connected to air bladder
cells
404-1 through 404-20 of the air mattress by relatively short, flexible
electrically
insulating air tubes 408-1 through 408-20.
Figure 13 illustrates in more detail the construction of wave generator
module 401 of soliton traveling wave air apparatus 400.
As shown in Figure 13, wave sequence generator 410 of wave
generator module 401 has 10 electrical output terminals 423-1 through 423-10
and
a common ground terminal 424. Wave sequence generator 410 contains electronic
circuitry which is powered by 12-volt D.C. power supplied to +12-volt and
ground
terminals 425, 426, respectively, of the wave generator module from +12-volt
and
ground output terminals 427, 428 of D.C. power supply 420. Wave sequence
generator 410 emits sequentially on output terminals 423-1 through 423-10
thereof
12-volt square-wave like air bladder cell selector pulses 429-1 through 429-
10, as
shown in Figures 18 and 19. As shown in Figure 13, wave sequence generator 410
has an input control port 430 which is connected to an output control port 431
of
control electronics module 419. Control electronics module 419 has Mode and
Frequency control input ports 432, 433 which may be connected to manually
operable switches, or to a data port such as an RS 232 port or a USB port.
In response to Mode and Frequency select control signals input to
control electronics module 419 on input terminals 432 and 433 thereof, the
frequency and sequencing pattern of bladder selector pulses 429 emitted on
terminals 423-1 through 423-10 of the wave sequence generator 410 can be
varied
by a user of apparatus 400. Thus, for example, a first, basic operating mode
of
apparatus 400 may consist of a first "downward" (head-to-foot) sequence of
bladder
selector pulses 429-1 through 429-10 emitted sequentially on terminals 423-1
through 423-10 of wave sequence generator 410, as shown in line 1 of Figure
18.
¨44 -
CA 2939545 2018-01-19
As indicated by the numbers in parentheses in line 1 of Figure 18, a
second operating mode of wave sequence generator 410 may be selected which
causes a second, "upward" sequence of bladder selector pulses 429 to be
emitted
sequentially in terminals 423-10 through 423-1 of wave sequence generator 410.
As will be described in detail below, wave sequence generator 410 desirably is
controllable to output other sequential patterns of pulses 429.
According to the invention, wave sequence generator 410 is also
controllable in response to signals input to frequency control port 433 of
control
electronics module 419 and conveyed to wave generator control port 430 to vary
the
repetition rate frequency of bladder selector pulses 429 emitted by the wave
sequence generator. As will be explained in detail, a typical range of periods
of
bladder selector pulses 429-1 through 429-10 on the ten output terminals 423-1
through 423-10 of wave sequence generator 410 of apparatus 400 would be from
about one to two seconds to about Ito 10 minutes. Thus, the total time period
for
emitting a sequence of 10 equal length pulses 429-1 through 429-10 on
terminals
423-1 through 423-10 of wave sequence generator 410 may vary over a typical
range of about 10 to 20 seconds to 20 to 100 minutes.
From the foregoing description of functions of wave sequence
generator 410 and control electronics module 419, those skilled in the art
will
recognize that those functions may be readily implemented by a suitably
programmed microprocessor, micro controller, programmable logic controller
(PLC)
or similar programmable electronic controller device. In an example embodiment
of
the present invention which was tested, wave sequence generator 410 included a
PIC model 16C58B Programmable Interrupt Controller, the ten output ports of
which
were connected to input terminals of ten transistor driver switches. As will
be
described in detail below, bladder selector pulses 429 on output terminals 423-
1
through 423-10 of wave sequence generator 410 are used to actuate individual
solenoid valves to an ON configuration for time periods based on the duration
of the
bladder selector pulses. Thus those skilled in the art will recognize that the
current
¨ 45 -
CA 2939545 2018-01-19
and voltage drive characteristics of wave sequence generator 410 are dependent
on
the number and electrical characteristics of the solenoid valves used in
apparatus
400. The example embodiment of the invention tested used12-volt solenoid
valves
having a coil resistance of about 120 ohms.
As shown in Figure 13, output terminals 423-1 through 423-10 of wave
sequence generator 410 are also connected to input ports 435-1 through 435-10
of
control electronics module 419. Control electronics module 419 includes
electronic
circuitry for processing bladder selector pulses 429 emitted from wave
sequence
generator 410 and input to input terminals 435-1 through 435-10 of the control
electronics module, and for emitting valve control signals V1-V7 on output
terminals
436-1 through 436-7, and solenoid valve drive signals SV1-SV7 on output
terminals
437-1 through 437-7. As shown in Figure 13, control electronics module 419 has
a
Deflation Pulse Width-adjust input port 438, and an Inflation Pulse Width-
adjust
input port 439. As is also shown in Figure 13, control electronics module 419
may
optionally have a pressure transducer signal input port 440, a rapid-deflate
command input port 441, and a rapid-inflate command input port 442.
As may be understood by referring to Figures 13 and 18, control
electronics module 419 produces on output ports thereof electrical control
signals, in
response to command and status signals input to various input ports of the
module.
As will be clear from the ensuing discussion of other functions of control
electronics
module 419, the circuitry of that module may be implemented as a micro
controller,
microprocessor, or PLC. An embodiment of control electronics module 419 which
was constructed to test various embodiments of a traveling wave air mattress
apparatus 400 according to the present invention employed a combination of
separate integrated circuit modules, relays, and semiconductor logic and
driver
components.
Referring to Figure 13, it may be seen that air pressure pulse
generator module 414 of soliton traveling wave air mattress apparatus 400
according to the present invention includes a pressure/vacuum pump 444, which
¨ 46 -
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has a vacuum inlet port 445, and a pressure outlet port 446. Vacuum inlet port
445
and pressure outlet port 446 are connected through an arrangement of valves V1-
V7 and coupling tubes to pressure/vacuum outlet port 415 of air pressure
generator
module 414 of wave generator module 401, which is in turn connected through
air
inlet tube 416 to manifold inlet port 417 of air mattress interface module
405, as
shown in Figure 12.
As shown in Figure 13, valves V1-V7 of air pressure pulse generator
414 of wave generator module 401 may be identical, normally OFF (NO), two-way
solenoid actuated air valves. Thus, for example, valve V1, reference
description
number 477-1 in Figure 13, has a solenoid activator SV1 (448) which has a
ground
return terminal 449-1 and a 12-volt actuation terminal 450-1, which is
connected to
SV1 drive terminal 437-1 of control electronics module 419. A 12-volt signal
level
on solenoid valve drive terminal SV1 (437-1) of control electronics module 419
actuates valve SV1 to an ON position, in which air passes freely between first
and
second opposed ports 451A, 451B of the valve. Conversely, when the 12-volt
actuating signal is removed from solenoid terminal SV1, valve V1 returns to a
closed, OFF position, in which air flow between the ports of the valve is
blocked.
Table 3 lists the valves V1-V7 shown in Figure 13, and identifies the function
of
each valve.
TABLE 3
VALVE ELEMENT FUNCTION
NUMBER
V1 447 Manifold vacuum
V2 453 Manifold pressure
V3 459 Pump recirculate/bypass
V4 465 Pump vacuum inlet
V5 471 Pump exhaust to atmosphere
V6 477 Vacuum
inlet from/exhaust to atmosphere
V7 483 Pressure regulator bypass
¨ 47 -
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As shown in Figure 13, valves V1-V7 (reference designation numbers
477-1, 453, 459, 465, 471, 477, 483) are interconnected through an arrangement
of
Tee-couplers and tubes between pressure/vacuum pump 444 and pressure/vacuum
outlet port 415 of air pressure pulse generator 414. The Tee-couplers include
five
couplers 489, 490, 491, 492, 493. When an optional pressure transducer 494 is
included in apparatus 400, it is connected to pressure/vacuum outlet port 415
of
wave generator module 401 through a sixth Tee-coupler 495.
Air pressure pulse generator 414 of wave generator module 401 is
used to introduce pulses of air into individually selectable air bladder cells
404 of air
mattress 403 (see Figure 12) in a manner which is described in detail below.
The
construction and functions of apparatus 400 which enable transmission of air
pressure pulses to selected air bladder cells 404 may be best understood by
referring to Figure 14 in addition to Figures 12, 13, and 18.
As shown in Figure 14, air mattress interface module 405 includes a
distributor manifold 496 what has an inlet port 417 for pressurized air which
is
connected through a single flexible air tube 416 to air pressure pulse
generator 414
of wave generator module 401, as shown in Figure 12 and previously described.
Distributor manifold 496 has a series, e.g., ten, of air outlet ports 497-1
through 497-
10. Each air outlet port 497 is connected through a flexible air tube to a
first port
.. 498 of a solenoid air bladder cell valve 499. Each solenoid air bladder
cell valve
499 is a normally OFF valve that permits passage of air between first port 498
and a
second port 500 thereof, only when solenoid actuator 501 of the valve is
actuated
by a 12-volt signal impressed on input terminal 502, and return terminal 503
of the
solenoid is connected to a ground return through ground return conductor RTN1
(504).
As may be understood by referring to Figures 12 and 13 in addition to
Figure 14, each solenoid drive terminal 502-1 through 502-10 of the solenoid
valves
499-1 through 499-10 is connected through a separate insulated conductor 505-1
through 505-10 of interface cable 411 to a separate output terminal 423-1
through
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423-10 of wave sequence generator module 410. Also, common ground conductor
line 504 of air mattress interface module 405 is connected through a separate
conductor of cable 411 to ground return output terminal 424 of wave sequence
generator 410.
From the foregoing description, it will be understood that when a 12-
volt D.C. actuating signal is emitted from an output terminal, e.g., 423-1 of
wave
sequence generator 410, a corresponding air bladder cell valve, e.g., 499-1 of
air
mattress interface module 405, will be actuated to an ON configuration. In
this ON
configuration, there is pneumatic communication between second port 500 of the
valve 499 and pressure/vacuum outlet port 415 of air pressure pulse generator
414
of wave generator module 401. Thus, as shown in Figure 14, air pressure pulses
in
pressure/vacuum outlet port 415 of air pressure pulse generator 414 are
conducted
to outlet port 501-1 of valve 499-1, which may be connected to inlet port 409
of an
individual air bladder cell 404.
Optionally, as shown in Figure 14, the second port of an air bladder
cell inflation valve 499 may be coupled to a pair of air bladder cells through
a Tee-
coupler 506. Thus, as shown in Figure 14, a first Tee-coupler 506-1 enables
air
pulses to be conveyed simultaneously to a pair of adjacent air bladder cells
404-1,
404-2. With this arrangement, a 10-outlet port distributor manifold 490 and
ten air
bladder cell inflation valves 499 may be used to convey air pressure pulses to
all 20
of the air bladder cells of a 20-cell air mattress.
As may be understood by referring to Figures 12, 13, and 14, in
response to electrical control signals input to air pressure pulse generator
414 from
wave sequence generator 410 and control electronics module 419, the air
pressure
pulse generator produces in pressure/vacuum outlet port 415 air pulses which
are
conveyed through air mattress interface module 405 to selected air bladder
cells
404-1 through 404-20. As shown in Figure 20, each air pulse 510 consists of a
negative differential pressure component beginning at time Ti and ending at
time
T2 of the pulse. The negative differential pressure component T1-T2 here
refers to
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a reduction of pressure at the inlet port 409 of an air bladder cell 404 that
causes
the air bladder cell to partially or fully deflate.
In a first, active deflation mode of operation of pressure pulse
generator 414, pressure reduction component T1-T2 of air pulse 510 is produced
by
actuating valves of apparatus 400 in a manner which connects the inlet port
409 of
an air bladder cell 404 through valves and tubes to the vacuum or suction
inlet port
445 of pressure/vacuum pump 444. In a second, passive deflation mode of
operation of air pressure pulse generator 414, the deflation component T1-T2
of air
pulse 510 is produced by actuating valves of the apparatus 400 in a manner
which
creates a path for air under pressure in an air bladder to be exhausted to the
atmosphere.
As shown in Figure 20, air pressure pulse 510 includes a second, re-
inflation component during the time interval T2-T3. The re-inflation component
T2-
T3 is produced by actuating valves of apparatus 400 in a manner which creates
a
pathway for pressurized air discharged from pressure outlet port 446 of
pressure/vacuum pump 444 to the inlet port 409 of an air bladder cell 404.
Details of the operation of air pressure pulse generator 414 which are
effective in producing a sequence of air-pressure pulses 510 of the type shown
in
Figure 20, and conveying the pulses to an air mattress 403, of the type shown
in
Figure 14 may be best understood by referring to Figures 13 and 18.
As may be understood by referring to Figures 13 and 18, control
electronics 419 contains circuitry which produces a sequence of control
signals
SV1-SV7 for valves V1-V7 upon receiving a bladder selector pulse 429 from any
one of the ten output ports 423-1 through 423-10 of wave sequence generator
410,
which ports are connected to input ports 435-1 through 435-10 of control
electronics
module 419. For example, as shown in Figure 18, control electronics module 419
produces in response to the leading, positive-going edge of a first bladder
selector
pulse 429-1 on output in terminal 423-1 of wave sequence generator 410 the
leading edge of a positive-going, Deflate pulse P1. As shown in Figure 18, the
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duration (t12-t11) of Deflate pulse P1 is adjustable as indicated by the
variable time
location of the trailing edge of the pulse at t12. The duration of Deflate
pulse P1
may be adjusted by a signal on input control terminal 432 of control
electronics
module, for example, by varying the time constant of a monostable
multivibrator, or
ONE SHOT, triggered by the leading edge of a bladder selector pulse 429-1 at
time
t11.
As shown in Figures 13 and 18, pulse V1 is output on solenoid valve
drive terminal SV1 (437-1) to thus turn valve V1 ON. As shown in Figure 18,
valve
V4 is also ON at the same time as valve V1, thus providing an air path between
vacuum inlet port 445 of pump 444, pressure/vacuum outlet port 415 of air
pressure
pulse generator 414, pressure/vacuum inlet port 417 of the distributor
manifold, air
bladder cell valve 493-1, and selected air bladder cell 404-1. At the same
time
valve actuator drive signal SV5 is also positive, thus enabling pressurized
air
discharged from pressure outlet port 446 of pressure/vacuum port to pass
through
pressure regulator 512 and exhausted into the atmosphere.
Referring still to Figures 13, 18, and 20, it may be seen that the
negative-going, trailing edge of Deflate pulse P1 triggers the leading edge of
an
Inflate pulse P2. As shown in Figure 18, the time location of the trailing
edge of
inflate pulse P2 is also adjustable to thus adjust the duration of deflate
pulse P2. As
will be readily understood by those skilled in the art, P2 may be generated by
a
second one-shot triggered by the trailing edge of deflate pulse P1.
Referring to Figure 13, it may be seen that when manifold vacuum
valve V1 is turned OFF at the end of Deflate pulse P1, manifold pressure valve
V2
is turned ON, thus providing an air path from pressure outlet port 446 of
pressure/vacuum pump 444 to an air bladder cell, such as a selected air
bladder
cell 404-1. As may also be understood by referring to Figures 13 and 18,
during
Inflate pulse P2, pump vacuum inlet valve V4 and vacuum atmosphere vent valve
V6 are ON, providing inlet air to vacuum inlet port 445 of pressure/vacuum
pump
444.
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Optionally, an accumulator of the type shown as element 347 in Figure
11B may be used in a hermetically sealed modification of air pulse generator
414
shown in Figure 13. In this modification, the exhaust port outlet of pump
exhaust
vent valve V5 (471) would be connected through an optional check valve to a
first
port of an accumulator, and the inlet/exhaust port of vacuum inlet valve V6
(477)
would be connected to a second port of the accumulator.
Referring to Figure 18, it may be seen that after the last pulse in a
sequence of bladder selector wave pulses 429 has been emitted from wave
sequence generator 410, e.g., after a sequence of 10 01 20 pulses, apparatus
400
may selectably continue to cyclically output sequences of control pulse
signals, or
enter into a rest mode. As indicated by the solid lines at the right-hand side
of
Figure 18, during a rest period of apparatus 400, pump recirculate/bypass
valve V3
(459) may be turned on. Alternatively, as shown in dashed lines, a resting
mode
may be selected in which valves , V4(465) , V5 (471) and V6(477) are turned on
to
provide venting to the atmosphere of both vacuum inlet port 445 and pressure
outlet
port 446 of pressure/vacuum pump 444. Using either of the foregoing rest modes
eliminates the necessity for switching pressure/vacuum pump 444 on and off
during
operation of apparatus 400. Figure 19 illustrates a second, passive deflation
mode
of operation of apparatus 400.
In the passive deflation mode, V4 is closed and valves V1 and V6 are
opened during the deflation component of an air pressure pulse, allowing
pressurized air from an air bladder cell 404 to escape to the atmosphere
through an
open port of valve V6, rather than being connected to vacuum inlet port 445 of
pressure/vacuum pump 444. As will be explained below, the slower deflation
rate of
an air bladder cell in a passive deflation mode facilitates a novel and
advantageous
mode of operation of apparatus 400.
Table 4 summarizes the configuration of valves V1-V6 for the above-
described operational modes of wave generator module 401.
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TABLE 4
ACTIVE PASSIVE INFLATE REST REST
DEFLATE DEFLATE
(RECIRCULATING (VENTING PUMP)
PUMP)
VALVE STATE STATE STATE STATE STATE
V1 ON ON OFF OFF OFF
V2 OFF OFF ON OFF OFF
V3 OFF ON OFF ON OFF
V4 ON OFF ON OFF ON
V5 ON ON OFF OFF ON
V6 OFF ON ON ON ON
Figures 20, 21A, and 21B illustrate how soliton traveling wave air
mattress apparatus 400 produces soliton traveling waves of body support forces
on
the surface of air mattress 403.
As shown in line 1 of Figure 21A, before apparatus 400 is powered on,
an air mattress 403 of the type shown in Figure 12 having, for example, 20 air
bladder cells 404 (only the first 10 are shown) may be in a deflated state. At
time
Ti, a first pulse of air 510 (see Figure 20) is input to first air bladder
cell 404-1 of the
air mattress 403.
As shown in Figure 20 and has been described above, air pulse 510-1
has a first, deflation component beginning at time T1 and ending at time T2.
Since
all of the air bladder cells 404 of air mattress 404 were presumed to be
deflated,
there will be no change in the contour of air bladder cell 404 during the
period T1-
T2. However, if any air bladder cell were partially deflated, it will be fully
deflated by
the deflation component of air pulse 510 during the period Ti to 12.
At time T2, the inflation component of air pulse 510-1 begins to inflate
first air bladder cell 404-1. The inflation component of air pulse 510-1
continues
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until time T3. The duration of inflation pulse component T3-T2 of air pulse
510, and
the maximum inflation pressure, which is adjusted by adjusting pressure
regulator
511, are selected to inflate air bladder cell 404-1 to a pre-determined steady-
state
pressure PS, which causes the upper body support surface 512 of the air
bladder
cell to assume the generally semi-cylindrically shaped contour shown in line 2
of
Figure 21A
Referring to lines 3 through 10 of Figure 21A, it may be seen that
successive air bladder cells 404-2 through 404-20 are sequentially selected
and
inflated by wave generator module 401, resulting in a fully inflated air
mattress 403
as shown in the last line of Figure 21A.
Figure 21B illustrates how apparatus 400 produces a soliton traveling
wave of body support force reduction on the upper surface 512 of air mattress
403.
As shown in Figure 21B, after a first cycle of 10 01 20 pulses emitted
by wave sequence generator 410 to initialize an air mattress 403 to a fully
inflated
state as shown in the last line of Figure 21B, a second and successive cycles
of
wave sequence pulses are effective in producing a soliton traveling body
support
force reduction wave on the upper surface 512 of air mattress 403. Thus, as
shown
in line 2 of Figure 21B, during the deflation period T1-T2 of a first, head-
end air
bladder cell 404-1, that air bladder cell is deflated to thus reduce the
support force
exerted by the air bladder cell on a body part. The duration of this deflation
component T1-T2 of the air pulse 510 may be adjusted to any suitable value,
such
as 1 to 5 minutes or longer.
At time T2 of a first deflation pulse, air bladder cell 404-1 is re-inflated
to a pre-determined quiescent pressure, during the time interval T2 to 13. The
minimum duration of inflation component 12 to T3 of air pulse 510 is typically
determined by how long it takes to inflate an individual air bladder cell 404
to a
desired pressure, which for a relatively small pressure/vacuum pump having an
outlet pressure of 36 PSI and an air flow rate of 5.5Ipm would be about 30
seconds
to one minute.
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As shown in lines 3-11 of Figure 21B, sequentially deflating and re-
inflating the remaining air bladder cells 404-2 through 404-10 or 404-20 of a
10 or
20 bladder mattress causes a soliton traveling wave of body support force
reduction
to progress from one end to the other end of air mattress 403. For example, if
the
first air bladder cell 404-1 is located at the head-end of a bed, a traveling
wave of
body support force reduction 513 will be propagated from left to right a shown
in
Figure 21B, i.e., from the head-end to the foot-end of air mattress 403.
As may be understood by referring to Figure 21B, deflation of each air
bladder cell 404 is initiated at the times T1, - - T10 coinciding with the
beginning of a
sequence of air bladder selector pulses 429-1 through 429-10, as shown in
Figure
18. At the end of each bladder selector pulse, the selected air bladder cell
is left in
a fully inflated state. Thus, at the time T1, coincident with a first bladder
selector
pulse 429-1, air bladder cell 404-1 becomes deflated, and at the end of pulse
429-1,
is fully re-inflated.
In a basic embodiment of the apparatus 400 according to the present
invention shown in Figures 12,13, and 14, a wave sequence generator 410 having
ten output ports, and a distributor manifold having ten outlet air ports in a
simplified,
low-cost configuration, are used to control a 20-air bladder cell air
mattress. This
configuration also utilizes only ten air bladder cell valves 499 to minimize
cost and
complexity.
As shown in Figure 14, the ten-port wave sequence generator 410,
ten-port distributor manifold 490, and ten air bladder cell valves 499 are
enabled to
control an air mattress 403 which has 20 air bladder cells 404-1 through 404-
20, by
driving a pair of air bladder cells 404 from each distributor outlet port
using a single
air bladder cell valve 499 connected to each port. Figure 21C illustrates
generation
of a soliton traveling body support force reduction wave in which adjacent
pairs of
air bladder cells 404 are sequentially deflated and re-inflated to produce a
head-to-
foot traveling body force support wave on an air mattress 403 having 20 air
bladder
cells 404.
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Figures 13, 15, and 21D illustrate a modification of apparatus 400
which uses a 10-output port wave sequence generator 410, a 10-outlet port
distributor manifold 490, and 20 air bladder cell valves 499 to individually
inflate and
deflate 20 air bladder cells. As shown in Figure 15, each of the 10 output
ports 497-
1 through 497-10 of ten-output port distributor manifold 490 is coupled
through a
Tee coupler 515-1 through 515-10 to a pair of air bladder cell valves 517A-
517B to
a pair of air bladder cells 404-1, 404-2 through 404-19, 404-20. Each air
bladder
cell valve 517A has a solenoid actuator which has a 12-volt input terminal
519A and
a first ground return input terminal 520A. Similarly, each second bank air
bladder
cell valve 517B has a solenoid actuator which has a 12-volt input terminal
519B and
a second ground return input terminal 520B.
As shown in Figures 13 and 15, the 12-volt solenoid actuator input
terminals 519A, 519B of each pair of air bladder cell valves 517A, 517B are
connected to a single output terminal 423 of wave sequence generator 410
through
a single insulated conductor 521 of cable 411. The first ground return
terminal
520A of the solenoid actuator of each air bladder cell valve 517A is connected
to a
first common return conductor RTN1 (522). Also, the second ground return
terminal
520B of each air bladder cell valve 517B is connected to a second common
return
conductor RNT2 (523).
As shown in Figure 13 and 15, RTN1 and RTN2 conductors are
deployed from air mattress module 402 to control electronics module 419 of
wave
generator module 401. As shown in Figure 13, RTN1 conductor 522 and RTN2
conductor 523 are connected to the B and C contacts of a SPDT relay 525. Relay
525 is driven by a toggle flip-flop FF2 (not shown) in control electronics
module 419.
As may be understood by referring to Figure 18, toggle FF2 is triggered
alternately
between SET and RESET states at the end of each 10 inflation pulses P2. With
this arrangement, it will be understood that when power is first applied to
control
electronics module 419, either RTN1 line or RTN2 line will be connected to
ground
through contacts of relay 525. In this first position of relay 525, a sequence
of 10
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pulses 429-1 through 429-10 will actuate air bladder cells valves 517A-1
through
517-10, or 517B-1 through 517B-10. After the 10th pulse 429-10 is input to
control
electronics module 419, flip-flop FF2 will be toggled to a different state as
shown in
the last line of Figure 18. With the foregoing arrangement, a sequence of
deflating
and re-inflating only the 10 odd-number air bladder cells 404 of an air
mattress 403
alternating with a sequence of deflating and re-inflating only even-number air
bladder cells 404, results in the generation of alternating odd and even head-
to-toe
body support force waves, as shown in Figure 21D.
Figure 16 illustrates another variation of the soliton traveling wave air
mattress 400 according to the present invention. This variation employs a
router
manifold interposed between the distributor manifold and air bladder cells
shown in
Figure 15 and enables creating a non-alternating, consecutive sequence of air
bladder cell deflation and re-inflation cycles in an air mattress 403 having
20 air
bladder cells 404 using a ten-output port distributor manifold.
Figure 17 illustrates another variation of the apparatus 400 which uses
a pair of 10 output port distributor manifold 490A, 490B, 20 air bladder cell
valves,
and a ten-output terminal wave sequence generator to produce soliton traveling
body support force variation waves on an air mattress 403 having 20 air
bladder
cells, using the toggle flip-flop FF2 as described above.
Figure 21 E illustrates the formation of a backward, foot-end towards
head-end traveling body support force wave which may be generated using the
traveling wave apparatus of Figures 12-17.
Figure 21F illustrates another type of soliton body support force
reduction wave which can be produced by the apparatus 400 according to the
present invention, in which the operating mode of the wave sequence generator
is
selected to produce simultaneous up and down soliton traveling waves of pulses
429. It should be noted that wave sequence generator 410 may be programmed to
enable production of a virtually unlimited variety of wave sequences. Also, as
shown
in Figure 13, control electronics module 419 optionally includes Rapid Inflate
and
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Rapid Deflate input ports, which would be used to command wave generator
module 410 to output inflate only or deflate only signals 429 simultaneously
on all
output ports 423 of the wave generator module, and a command signal turn on
pressure regulator bypass valve V7 (483).
5 Figures 22-
24 illustrate a modification of traveling wave air mattress
400. As may be understood by referring to Figures 20 and 22, the bladder
selector
pulses 429 output sequentially from wave sequence generator 410 are typically
used to generate a pattern of deflation and re-inflation pulses 510 which
travel
sequentially from each air bladder cell 404 to the next adjacent cell, each
pair of air
10 bladder
cells to the next adjacent pair, each odd air bladder cell to the next odd air
bladder cell, and each even air bladder cell to the next even air bladder
cell.
However, it should be recognized that it may in some cases be desired to omit
certain air bladder cells from the deflation/re-inflation sequence. For
example, if
certain bladder cells 404 of the air mattress are very lightly loaded, or
simply not
loaded at all because a short person is lying on the air mattress, it may be
desired
to skip the lightly loaded or unloaded air bladder cells, affording the
possibility of
decreasing the times between which loaded air bladder cells are pulsed.
Therefore, apparatus 400 according to the present invention optionally
includes elements which provide a novel and efficient means of monitoring
average
loading of individual air bladder cells, and utilizing that information to
provide
command signals to wave sequence generator module 410 to omit inputting air-
pulse command signals 429 to air bladder cells 404 which are subjected to
average
weight load forces below a predetermined threshold value.
The novel structure and method of periodically sensing minimum
weight loads of individual air bladder cells 404, and responding to the
sensing of
minimum loading by periodically omitting application of force-reducing
deflation/inflation pulses to such cells may be best understood by referring
to
Figures 13, 18, 19, 22, 23, and 24.
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As shown in Figure 23, when an air pressure pulse 510 is applied to
an air bladder cell 404 that is subjected to a significant weight load of, for
example,
to 10 pounds, that air bladder cell will deflate relatively rapidly to a pre-
determined
pressure PT at a time T.L., as indicated by the solid line in Figure 23.
5 On the other hand, an unloaded or lightly loaded air bladder cell
will
take longer until time TU to deflate, as indicated by the dashed line in
Figure 23.
Consequently, by measuring the air pressure in pressure/vacuum outlet port 415
of
air pulse generator by pressure transducer PT (485) at a time TL after the
initiation
of the deflation component of air pulse 510, and determining that it has not
yet been
reduced below the threshold pressure PT, it can be concluded that there is
little or
no load on that particular air bladder cell. Accordingly, the wave sequence
generator 410 may in this case be commanded by a signal from control
electronics
module 419 to skip issuing a square wave bladder selector pulse 424 signal to
deflate that air bladder cell, during the next sequence of bladder selector
pulses 429
emitted by the wave sequence generator.
The time difference between loaded and unloaded reduction of
inflation pressure crossing the PT threshold my be enhanced by utilizing the
passive
deflation mode described previously. Thus, as shown in Figures 18 and 19, flip-
flop
FF2 may be toggled at the end of each 10 or 20 pulses 429 to thus switch
between
active and passive deflation modes as desired to thereby increase resolution
in
determination of the of differences in weight loading of the air bladder cells
404.
Figure 24 illustrates a sequence of air bladder cell deflation/re-inflation
pulses 510, in which pulses to air bladder cells 2, 3, 5, and 6 have been
omitted
because they have been determined in a previous sequence of
deflation/inflation
pulses to have been subjected to a time-average weight load below a
predetermined value which is insufficient to result in those cells deflating
to or below
a threshold pressure PT on or before time TL.
Those skilled in the art will recognize that the time sequences of air
pressure pulses 63 shown in Figures 3A and 3B, considered collectively, have a
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characteristic of soliton traveling waves, i.e., each sequence consists of a
solitary
traveling pressure wave having a constant amplitude. As has been described
above, the sequence of air pressure pulses depicted in plots 1-6 of Figure 3A,
when
input into a series of air bladder cells, such as the one shown in Figure 7A,
result in
a traveling soliton wave of pressure variation in the air bladder cells, which
in turn
produces a soliton traveling wave of body support force variation, i.e.,
reduction, as
depicted in Figure 21B.
Another characteristic of a soliton traveling wave is that it maintains its
amplitude and shape in spite of collisions with other soliton traveling waves.
The
lines labeled T9-T2 of Figure 21F illustrates that the soliton traveling waves
of body
support force in air mattresses according to the present invention also have
this
characteristic. Thus as shown in lines T9-T2 of Figure 21F, a first soliton
wave of
traveling body support force traveling from left to right, e.g., from the head-
end to
the foot-end of an air mattress, collides with a second soliton wave of
traveling body
support force traveling from right to left, e.g., from the foot-end of a
mattress
towards the head-end, at time T10. At time Ti, the downward and upward soliton
pulses traveling waves have passed through each other without change.
Figure 25 illustrates a first modification 614 of the air pressure pulse
generator component or module shown in Figure 13 and described above, which
requires only five valves rather than the seven shown in Figure 13.
In modified air pressure pulse generator module 614, air bladder cells
404 (see Figure 12) are initially inflated en masse, as follows. With valves
V1 (477-
1), V3 (459), and V5 (471) in closed, OFF, positions, and valves V6 (477) and
V2
(453) in open, ON positions, pressure/vacuum pump 444 is powered on. This
action enables air to be drawn from the atmosphere through valve V6 (477),
vacuum inlet port 445 of pressure/vacuum pump 444, expelled from outlet port
446
of the pressure/vacuum pump, and passed through valve V2 (453) to air bladder
cells 404, e.g., the twenty air bladder cells 404-1 through 404-20 shown in
Figure
12. After a time period sufficient to inflate all twenty air bladder cells 404-
1 through
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404-20 to a desired quiescent air pressure valves V6 (477) and V2 (453) are
actuated to an OFF position, and valve V3 (459) is actuated to an ON position,
enabling air to be circulated through V3 and pressure/vacuum pump 444 during a
rest interval. During this rest interval, pump 444 may be powered off or
remain on.
Following an initial rest interval after inflation of all air bladder cells
404-1 through 404-20, a soliton traveling wave of air pressure and resulting
traveling
soliton body support force wave in air mattress module 403 may be initiated. A
first
step in initiating a traveling air pressure pulse wave consists of issuing a
manifold
selector valve opening signal 429 to a selected air bladder cell selector
valve or
valves, e.g., valve 499-1 connected to air bladder cells 404-1 and 401-2, as
shown
in Figure 18. Next, in response to control signals issued from control
electronics
module 419, valve V3 (459) is closed, and valves V1 (477-1) and V5 (471) are
opened. As may be understood by referring to Figure 25, this valve
configuration
enables air to be withdrawn from a selected air bladder cell or cells 404
through
valve V1 (477-1), vacuum inlet port 445 of pressure/vacuum pump 444, through
outlet port 446 of the pressure/vacuum pump, and through valve V5 (471) to the
atmosphere.
The foregoing valve configuration in the initial, deflation part of an air
bladder cell pressure pulse is maintained for a time interval sufficient to
reduce air
pressure in a selected air bladder cell or cells to a pre-determined value.
At the end of a deflation period, valves V1, V2, V3, V5, and V6 are
actuated to the initial en masse inflation configuration described above.
Since
pressure/vacuum pump 444 need only have a capacity to fully deflate or re-
inflate
one or two air bladder cells in a period of, for example, one-half to two
minutes, the
time period for inflating a single air bladder cell with pressure/vacuum pump
operating at full capacity would be about one-twentieth that required to fully
inflate a
fully-deflated air mattress 403 having twenty air bladder cells. Thus, the
time
required to re-inflate a single fully-deflated air bladder cell 404 would
typically be
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about one-half to one minute versus ten to twenty minutes to fully inflate all
twenty
air bladder cells.
At the end of an initial deflation/re-inflation air pulse cycle as described
above, the apparatus may be programmed to enter a rest period of a selectable
duration, such as the time interval between T13 and T21 shown in lines 1 and 2
of
Figure 20. During the rest period, valves V1, V2, V3, V5, and V6 are
configured as
described above for the initial rest interval.
After a pre-determined rest period, second and successive air
pressure pulses may be applied to second and successive air bladder cells 404,
in
the same manner as described above.
It should be noted that modified pressure pulse generator 614 shown
in Figure 25 draws in air from the atmosphere through the inlet port of valve
V6
(459) and exhausts air to the atmosphere through the outlet port of valve V5
(471).
Figure 26 illustrates another modification of air pressure pulse
generator 414 shown in Figure 13, in which air cyclically exhausted from and
inlet to
air bladder cells is transmitted to and from one or more accumulators rather
than to
the atmosphere. In this modified, closed system, after an initial supply of
air such
as filtered air from the atmosphere is input to the apparatus to inflate all
air bladder
cells 404 and one or more accumulators, the air pressure pulse generator 714
may
be isolated from external air inlet sources and exhaust locations.
As shown in Figure 26, second modified pressure generator module
714 has, in addition to the five valves of first modified pressure pulse
generator 614,
two additional valves, V4 (477-2) and V7 (477-3).
As may be understood from the description above of the initial en
masse inflation of all air bladder cells of an air mattress, valve V4 (477-2)
may be
actuated to an ON position to enable an initial volume of air to be drawn in
from the
atmosphere or other source to inflate all air bladder cells 404, in a "rapid
inflate" or
en masse inflation mode.
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Similarly, it will be understood that valve V7 (477-3) may be actuated
to an ON position to exhaust air from all air bladder cells 404 to the
atmosphere in a
"rapid deflate" mode. However, cyclical deflation and re-inflation of selected
air
bladder cells by air pressure pulse generator 714 after all of the air bladder
cells 404
of an air mattress have been inflated is performed in isolation from the
atmosphere,
as will now be described.
Referring to Figure 26, it may be seen that second modified pressure
pulse generator 714 has in the lower, vacuum inlet arm thereof a valve V4
(465)
used to provide air from an external source such as the atmosphere to
initially
inflate all of the air bladder cells 404 of an air mattress 403. As shown in
Figure 26,
air pressure pulse generator 714 has in addition to external air inlet control
valve V4
(465), an additional air inlet valve V6 (478).
Air inlet valve V6 (478) has an inlet port connected to a sealed interior
space of a first accumulator, Accumulator 1. According to the invention,
Accumulator 1 may consist of one and preferably two additional air bladder
cells
404-21, 404-22, as may be understood by referring to Figure 27. When two air
bladder cells are used, they are connected in parallel by a tee-coupler. The
foregoing air bladder cells may be positioned at the foot end of air mattress
403.
Optionally, since the length of air mattress 403 would typically be greater
than that
required for a patient, the two foot-end air bladder cells 404-19 and 404-20
could be
used as Accumulator 1 air bladder cells.
Referring still to Figure 26, it may be seen that second modified air
pressure pulse generator 714 has in the upper, pressure output arm thereof a
valve
V7 (483) which is used to exhaust air withdrawn from all air bladder cells 404
of an
air mattress 403 to the atmosphere, in a rapid deflation mode.
As shown in Figure 26, air pressure pulse generator 714 has in
addition to external air exhaust valve V7 (483), and additional air outlet
valve V5
(498). Air outlet valve V5 (498) has an outlet port connected to the sealed
interior
space of a second accumulator, Accumulator 2. According to the invention,
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Accumulator 2 may consist of one and preferably two air bladder cells 404
connected in parallel by a tee-coupler as has been described above for
Accumulator
1.
Figure 27 illustrates a third embodiment 814 of an air pressure pulse
generator according to the present invention. As shown in Figure 27, air
pressure
pulse generator 814 includes an accumulator interconnect Tee 499 which has a
first
port thereof connected to the outlet port of outlet valve V5 (498), a second
port
connected to the inlet port of inlet valve V6 (478), and a third, accumulator
port.
The third, accumulator port is connected to a single accumulator of the type
.. described above, which consists of one and preferably two air bladder cells
404-21,
404-22 connected in parallel and located at the foot end of air mattress 403,
or in a
separate location such as below a support surface for air mattress 403.
The novel configuration of air pressure pulse generator modules 714,
814 shown in Figures 26 and 27 facilitates a novel Body Support Force
Equalization
Mode of operation of the air mattress inflation control apparatus shown in
those
figures, as will now be described.
Referring to Figure 27, after all air bladder cells 404 have been inflated
to configure air mattress 403 for use, and after a person has lain down on the
air
mattress, a Body Support Force Equalization Mode may be entered before
initiation
of cyclical generation of soliton traveling air pressure waves as described
above.
The purpose of the Body Support Force Equalization Mode is to decrease large
body support force concentration and imbalances to distribute body support
force
more equally. In other words, the result of utilizing the Body Support Force
Equalization Mode according to the present invention is to adjust the air
pressure in
individual air bladder cells 404 to average bias levels which are more nearly
equal to
one another, before superimposing a soliton traveling force reducing pressure
wave
in a sequence of air bladder cells 404.
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In the Body Support Force Equalization Mode according to the present
invention, all air bladder cells 404 of an air mattress 403 are first inflated
en masse
to a pre-determined pressure level.
Next, pressure/vacuum pump 444 is preferably turned off, and pump
bypass valve V3 (459) is turned on. Valves V1 (477-1), V2 (453), V5 and V6
(477)
are also actuated to ON positions at this time.
Next, sequence generator 410 receives a signal to output a sequence
of selector valve control signals 429-1 through 429-10 or 429-20 to manifold
selector valves 499.
When each individual manifold selector valve 499 is actuated to an
ON position, air in a selected air bladder cell 404 that is pressurized above
the
pressure in control accumulators 1 and 2, air flows into the accumulators,
thus
reducing body support force on a particular air bladder cell that is heavily
loaded, as
by a body protuberance.
Conversely, if the air pressure in a selected air bladder cell is less than
that in control accumulators 1 and 2, air flows from the accumulators to that
air
bladder cell. This results in re-distribution of body support forces to more
nearly
equal values as the manifold valves are actuated sequentially to ON positions.
After one or more repetitions of the manifold selector valve actuating
sequence described above, cyclical traveling pressure waves are initiated by
control
electronics module 419. In a preferred mode of operation, these pressure waves
would have a smaller amplitude than that used without prior equalization of
the
different bias pressure levels in the air bladder cells by utilization of the
Body
Support Force Equalization Mode. The amplitude of the traveling pressure waves
imposed on quiescent bias pressures in the air bladder cells is conveniently
reduced
by decreasing the duration of both deflation and re-inflation periods of a
traveling
air pressure pulse wave. Thus the traveling pressure wave may be speeded up
without requiring an increase in the volumetric flow rate of pressure/vacuum
pump
444.
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The Body Support Force Equalization Mode described above may be
initiated periodically, e.g., hourly, or optionally in response to sensed body
weight
redistributions above a pre-determined threshold value, which may be measured
by
an optional pressure or force sensor.
Figure 28 illustrates a modification of a basic embodiment of an air
mattress according to the present invention shown in 2A. Modified air mattress
503
shown in Figure 28 includes oval plan-view, annular ring-shaped parallel
tubular air
bladder cells 50 which are arranged in a concentric array. Each of air bladder
cells
504 has an air inlet port 509 which protrudes downwardly from a lower surface
of
the air bladder cell. In this arrangement, air bladder cells 504-1 through 504-
10 may
receive sequential pulses of air pressure variation to thus produce an the
upper
surfaces of the air bladder cells a soliton traveling wave of body support
force
variation. This soliton traveling wave has an elliptical ring-shaped wave
front that
travels radially outwardly from the center of mattress 503 to the outer
perimeter of
the air mattress, which is coincident with the outer perimeter of outermost
air
bladder cell 504-10 when air pressure pulses are introduced to air bladder
cells 504-
1 through 504-10 in ascending order, and radially inwardly when the pulses are
introduced into its air bladder cells in reverse order, i.e., 504-10 through
504-1.
Figure 29 illustrates a modification 523 of air mattress 503 shown in
Figure 28, in which oval ring-shaped air bladder cells 524 are segmented into
four
contiguous quadrant arc-shaped segments, 524-A, 524-B, 524-C, and 524-0. In
this embodiment, soliton traveling waves of body support force may be caused
to
travel in circumferential directions on the surfaces of the air bladder cells,
as well as
in radial directions as have been described above for the air mattress 503
shown in
Figure 28. Thus, for example, pulses of air pressure variation may be
sequentially
applied first to one or more air bladder cells 524A-1 through 524A-10in a
first
quadrant, e.g., the upper right-hand quadrant of air bladder cells shown in
Figure
29. Following introduction of first air pressure or pulses into air bladder
cells 524-A
in the first quadrant of air mattress 523, subsequent air pressure variation
pulses
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may be introduced sequentially into air bladder cells located into quadrants
B, C,
and D, to thus produce a soliton traveling wave of body support force
variation
which travels in a clockwise sense on the upper surface of air mattress 523.
In an exactly analogous fashion, counterclockwise soliton traveling
waves of body support force may be produced on the upper surface of air
mattress
523 by introducing pulses of air pressure variation sequentially into air
bladder cells
524 located in quadrants A, D, C, and B, respectively.
Figures 30 and 31 illustrate circular air mattresses 603 and 623 which
are exactly analogous in construction and function to oval air mattresses 503
and
523 described above, with the following single difference. Mattresses 603 and
623
are comprised of air bladder cells 604, 624 which have annular ring shapes
that
have a circular plan view rather than being oval-shaped. Thus air mattresses
603,
623 have an aspect ratio which is more suitable for matching the shape of a
chair or
wheel chair.
It may be understood by referring to Figure 30, air bladder cells 604-1
through 604-10 of air mattress 603 span a first (circumferential) area
dimension of
the mattress, and the soliton traveling wave of body support force reduction
travels
in a direction parallel to a second (radial) area dimension of the mattress.
It will be
readily understood that the mattresses shown in Figures 28, 29, and 31 also
have
air bladder cells that are arrayed in a first, circumferential direction and
that soliton
traveling waves travel in a radial direction on those mattresses.
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