U.S. patent application number 11/381631 was filed with the patent office on 2006-12-07 for vibrating patient support apparatus with a resonant referencing percussion device.
Invention is credited to Jean-Paul Dionne, Melanie Dostaler.
Application Number | 20060272097 11/381631 |
Document ID | / |
Family ID | 37307560 |
Filed Date | 2006-12-07 |
United States Patent
Application |
20060272097 |
Kind Code |
A1 |
Dionne; Jean-Paul ; et
al. |
December 7, 2006 |
VIBRATING PATIENT SUPPORT APPARATUS WITH A RESONANT REFERENCING
PERCUSSION DEVICE
Abstract
A vibrating patient support apparatus has a resonant referencing
percussion device preferably located internally to a cover of a
mattress of the apparatus. The percussion device delivers a
percussion or vibration at a controlled operating frequency that is
preferably slightly less than a resonant frequency located internal
to the mattress of the apparatus. With the various weight
distributions of a patient, the device is capable of determining
the ever shifting resonant frequency via control signals received
by a controller from a pressure sensor or accelerometer of the
device. Because the operating frequency is slightly less than the
natural resonating frequency, energy of the system is conserved.
Because the operating frequency is not the controller calculated
resonant frequency, wear on the device and potential damage is
minimized.
Inventors: |
Dionne; Jean-Paul; (Levis,
Quebec, CA) ; Dostaler; Melanie; (Quebec,
QC) |
Correspondence
Address: |
HOWARD & HOWARD ATTORNEYS, P.C.
THE PINEHURST OFFICE CENTER, SUITE #101
39400 WOODWARD AVENUE
BLOOMFIELD HILLS
MI
48304-5151
US
|
Family ID: |
37307560 |
Appl. No.: |
11/381631 |
Filed: |
May 4, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60677728 |
May 4, 2005 |
|
|
|
Current U.S.
Class: |
5/713 ;
5/710 |
Current CPC
Class: |
A61G 7/0507 20130101;
A61G 7/008 20130101; A61G 7/05784 20161101; A61H 9/0078 20130101;
A61H 2201/0138 20130101; A61H 2201/0142 20130101; A61H 2203/0443
20130101; A61H 2201/5056 20130101; A61G 7/05715 20130101; A61G
7/05769 20130101; A61G 2203/34 20130101; A61H 2201/0134 20130101;
A61H 2201/0146 20130101 |
Class at
Publication: |
005/713 ;
005/710 |
International
Class: |
A47C 27/10 20060101
A47C027/10; A47C 27/08 20060101 A47C027/08 |
Claims
1. A patient support apparatus for providing therapeutic treatment
to a patient, the patient support apparatus comprising: a loaded
state wherein at least a portion of the patient is supported by the
patient support apparatus; an unloaded state wherein the patient is
not being supported by the patient support apparatus; a percussion
device for producing a variable oscillating displacement at an
operating frequency; a resonating pad having at least one natural
resonant frequency when in the unloaded state and at least one
shifted resonant frequency when in the loaded state and wherein
each one of the at least one shifted resonant frequency corresponds
to a respective one of the natural resonant frequency; a controller
for electrically operating the percussion device; and a sensor for
communicating a control signal that corresponds to an amplitude of
vibration processed by the controller.
2. The patient support apparatus set forth in claim 1 further
comprising at least one shifted operating frequency wherein each
one of the shifted operating frequency is slightly less than a
respective one of the at least one shifted resonant frequency.
3. The patient support apparatus set forth in claim 1 wherein the
sensor is an accelerometer.
4. The patient support apparatus set forth in claim 3 wherein the
accelerometer is in contact with the resonating pad.
5. The patient support apparatus set forth in claim 1 further
comprising the percussion device having at least one bladder
constructed and arranged to inflate and deflate at the shifted
operating frequency.
6. The patient support apparatus set forth in claim 1 wherein the
sensor is at least one pressure sensor located in at least one of
the at least one bladder.
7. The patient support apparatus set forth in claim 6 further
comprising a variable speed pump controlled by the controller for
inflating and deflating the at least one bladder.
8. The patient support apparatus set forth in claim 7 wherein the
variable speed pump is an air pump.
9. The patient support apparatus set forth in claim 7 wherein the
variable speed pump is a fluid pump.
10. The patient support apparatus set forth in claim 1 further
comprising a percussion mode wherein the shifted operating
frequency is between one beat per second and seven beats per
second.
11. The patient support apparatus set forth in claim 10 further
comprising a vibration mode wherein the operating frequency is
between seven beats per second and twenty five beats per
second.
12. A patient support apparatus for providing therapeutic treatment
to a patient, the patient support apparatus comprising: a
cushioning member; a percussion device having a plurality of
bladders located below the cushioning member and a sensor; a
variable speed pump for flowing a pressurized medium into the
plurality of bladders; a valve system for controlling flow to and
from the bladders for inflation and deflation at a controlled
operating frequency; a controller for controlling the valve system
and the variable speed pump based in-part on a signal received from
the sensor.
13. The patient support apparatus set forth in claim 12 wherein the
cushioning member is a main bladder inflated by the variable speed
pump at a pressure controlled by the controller.
14. The patient support apparatus set forth in claim 13 further
comprising a resonating pad of the percussion device located
vertically between the main bladder and the plurality of
bladders.
15. The patient support apparatus set forth in claim 14 wherein the
resonating pad has at least one known natural resonating frequency
located within a range producible by the controller, variable speed
pump and valve system.
16. The patient support apparatus set forth in claim 14 wherein the
sensor is an accelerometer being in contact with the resonating
pad.
17. The patient support apparatus set forth in claim 12 wherein the
sensor is an accelerometer being in contact with the cushioning
member.
18. The patient support apparatus set forth in claim 12 wherein the
sensor is at least one pressure sensor located in at least one of
the plurality of bladders of the percussion device.
19. The patient support apparatus set forth in claim 12 further
comprising: the flow medium of the pump being pressurized air; and
the cushioning member being a main bladder of a firmness setting
device that receives controlled pressurized air from the pump.
20. The patient support apparatus set forth in claim 19 further
comprising a rotation device having two rotation bladders located
below the plurality of bladders of the percussion device, and
wherein the two rotation bladders are independently inflated and
deflated by the controller and receive pressurized air from the
pump.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. provisional
patent application Ser. No. 60/677,728, filed May 4, 2005, the
advantages and disclosure of this application is hereby
incorporated by reference.
FIELD OF THE INVENTION
[0002] The present invention relates generally to a patient support
apparatus and more particularly to a resonant frequency referencing
percussion device of a vibrating patient support apparatus.
BACKGROUND OF THE INVENTION
[0003] Patient support systems are well known in the art for
providing therapy to a patient. A typical patient support apparatus
comprises a mattress having a plurality of air bladders for
supporting the patient against the bias of gravitational forces, a
percussion device that alternates inflation and deflation of air
bladders to provide percussion and vibration therapy to the
patient, and a rotation device, usually positioned beneath the
mattress, to rotate the patient from side to side. Percussion,
vibration, and rotation therapy assist in reducing pulmonary
problems and bed sores, respectively.
[0004] One example of a rotation device in a mattress is shown in
U.S. Pat. No. 5,611,096 to Bartlett et al. and incorporated herein
by reference in its entirety. The rotation device of Bartlett et
al. has two selectively inflatable and deflatable air bladders
lying longitudinally beneath the mattress to provide rotation
therapy to the patient for reducing bed sores. A controller
including an operator input panel and display is used to control
the rotation device. The input panel includes a plurality of raised
buttons for advancing through and adjusting parameters associated
with rotation functions.
[0005] An example of a percussion or vibrating device in a mattress
is shown in U.S. Patent Application Publication No. 2004/0193078
A1, to Flick et al. and incorporated herein by reference in its
entirety. The percussion device of Flick et al. discloses a
vibrating pad having a plurality of bladders that fill and deflate
with the flow of air or fluid at a prescribed frequency controlled
by a controller causing the above mattress or mattress cushion to
vibrate. This vibration therapy is capable of reducing pulmonary
problems such as the accumulation of secretions in the lungs.
[0006] Unfortunately, controllers of known percussion devices do
not sense or process displacement amplitude with displacement
frequency of the vibrating media of the bladders. Hence, known
percussion devices are not capable of detecting and/or utilizing
natural resonant frequencies of the vibrating media. If the
operating vibration frequency of known percussion devices is too
distant from the natural resonant frequency, energy is wasted. If
the operating vibration frequency is unintentionally at the natural
resonant frequency, then damage or accelerated wear of the patient
support apparatus may occur.
SUMMARY OF THE INVENTION
[0007] A vibrating patient support apparatus has a resonant
referencing percussion device preferably located internally to a
cover of a mattress of the apparatus. The percussion device
delivers a percussion or vibration at a controlled operating
frequency that is preferably slightly less than a resonant
frequency located internal to the mattress of the apparatus. With
the various weight distributions of a patient, the device is
capable of determining the ever shifting resonant frequency via
signals received by the controller from a pressure sensor or
accelerometer of the device. Because the operating frequency is
slightly less than the natural resonating frequency, energy of the
system is conserved. Because the operating frequency is not the
controller calculated resonant frequency, wear on the device and
potential damage is minimized.
[0008] Preferably, the patient support apparatus includes a number
of other devices for patient comfort and therapeutic treatment
substantially located in a manageable and light weight mattress.
All the devices are generally light weight with moving parts
generally being bladders, thus relatively quiet when operating. For
ease of manufacturing and cost, a substantial portion or all of the
devices operate off of a common pump for preferably flowing
pressurized air to an assortment of bladders. For instance, the
percussion device preferably has bladders. Moreover, the apparatus
preferably has a bladder operated rotation device for rotating a
patient to minimize bed sores, a bladder operated firmness setting
device for providing patient comfort, and an air loss control
system for flowing air through the mattress to control
temperature.
[0009] Objects, features and advantages of the present invention
include a patient support apparatus that has a relatively
lightweight and manageable mattress having numerous devices for
therapeutic treatment. Other advantages of the apparatus include a
relatively simple and robust design that is inexpensive to
manufacture, reduces wear and warranty costs and reduces energy
consumption.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0010] Advantages of the present invention will be readily
appreciated as the same becomes better understood by reference to
the following detailed description when considered in connection
with the accompanying drawings wherein:
[0011] FIG. 1 is a perspective view of a patient support apparatus
of the present invention positioned on a hospital bed frame;
[0012] FIG. 2 is a cross-sectional view of the patient support
apparatus taken along the line 2-2 in FIG. 1;
[0013] FIG. 3 is a cross-sectional view of the patient support
apparatus taken along the line 3-3 in FIG. 1;
[0014] FIG. 4 is a schematic view of a control system of the
patient support apparatus;
[0015] FIG. 5 is a schematic view of an air flow system of the
present invention;
[0016] FIG. 6 is a schematic view of a resonant percussion device
of the present invention;
[0017] FIG. 7 is a partial enlarged cross section taken from the
circle 7 of FIG. 3;
[0018] FIG. 8 is a cross section similar in perspective to FIG. 7
and of a second embodiment of the patient support apparatus;
[0019] FIG. 9 is a cross section similar in perspective to FIG. 7
and of a third embodiment of the patient support apparatus;
[0020] FIG. 10 is a cross section similar in perspective to FIG. 7
and of a fourth embodiment of the patient support apparatus;
[0021] FIG. 11 is a cross section similar in perspective to FIG. 7
and of a fifth embodiment of the patient support apparatus; and
[0022] FIG. 12 is an amplitude versus frequency graph.
DETAILED DESCRIPTION OF THE INVENTION
[0023] Referring to the Figures, wherein like numerals indicate
like or corresponding parts throughout the several views, a
vibrating patient support apparatus of the present invention is
generally shown at 10.
[0024] Referring to FIG. 1, the patient support apparatus 10 of the
present invention is shown in combination with a mobile hospital
bed frame 12. As illustrated, the hospital bed frame 12 typically
includes a plurality of side rails 14 that can be lowered for
patient transfer and raised to confine a patient. The hospital bed
frame 12 can also include a plurality of adjustable sections
including an adjustable head section 16 that is pivotally
adjustable relative to a main body section 18 of the bed frame 12
to allow the patient to sit up while eating or visiting with
family.
[0025] Still referring to FIG. 1, the patient support apparatus 10
preferably comprises a generally self-contained mattress or pad
assembly 20 having a patient support surface 22. The mattress 20 is
referred to as being self-contained since a substantial portion of
the working components of the mattress 20 that are used to carry
out multiple functions, including a plurality of therapeutic
functions, are enclosed by a cover 24 of the mattress 20. The cover
24 can be any conventional material including, but not limited to
natural fibers, polymeric materials, or combinations thereof. The
cover 24 is preferably a vapor permeable material to be used in
conjunction with a low air loss mechanism 26 of the mattress 20
described below.
[0026] Referring to FIG. 4, a controller 72 of the patient support
apparatus 10 controls operation of a main pump 50 preferably
located externally of the mattress 20. The main pump 50 supplies a
controlled amount of pressurized air to multiple systems or devices
of the mattress 20 that are generally located internally to the
cover 24 of the mattress 20. These systems include; a low air loss
device 82 having a low air loss control system 56 and the low air
loss mechanism or perforated tubing 26, a firmness setting device
84 having a main valve system 58 and a main air bladder 36 (see
FIG. 3), a percussion device 86 having a percussion control system
60 and a percussion mechanism 38, and a rotation device 88 having a
rotation control system 62 and a rotation mechanism 40. The
rotation mechanism 40 is preferably two air bladders 42 located
beneath the percussion mechanism 38. The percussion mechanism 38 is
preferably a plurality of air bladders 39 located beneath the main
air bladder 36 of the mattress 20. The main air bladder 36,
percussion mechanism 38, and rotation mechanism 40 are supported
within the cover 24 of the mattress 20 by a base cushion 44
positioned within a perimeter of the frame 34. The base cushion 44
can be rigid or flexible and comprise an air bladder, or simply be
constructed of conventional bedding materials such as foam, and the
like.
[0027] Preferably, a pendant 28 of the controller 72 is supported
by a tower 30 coupled electrically to the mattress 20 and
preferably supported structurally by the bed frame 12. The pendant
28 includes user interface 32 of the patient support apparatus 10
used to operate at least a portion of the functions of the mattress
20. The user interface 32 is preferably of a touch-screen display
type that is well known to those skilled in the art for operator
input, as well as output, based upon the particular software used
to configure the user interface or touch-screen display 32. Here,
the touch-screen display 32 has input and output capabilities.
These features are shown in application Ser. No. 11/260,452, filed
Oct. 27, 2005, hereby incorporated by reference.
[0028] Referring to FIGS. 2-4, the mattress 20 has a generally
peripheral frame 34 of a conventional bedding frame material. Such
material can include, but is not limited to foam, polymeric
materials, metal, gels, or combinations thereof. Generally disposed
internally to the cover 24 of the mattress 20 is the main air
bladder 36 of the firmness setting device 84, which is positioned
within the perimeter of the frame 34 and immediately below an upper
portion of the cover 24. The main air bladder 36 acts as the
primary support for the patient and with a controlled flow of air
into and out of the bladder 36 can be useful in controlling the
temperature of the bedding material exposed to the patient.
[0029] The percussion-vibration mechanism 38 of the percussion
device 86 is positioned below the main air bladder 36, hereinafter
referred to as the percussion mechanism 38. The percussion
mechanism 38 provides both percussion and vibration therapy to the
patient. The particular therapy being employed is dependent on the
frequency or the number of beats per second generated by the
percussion mechanism 38. For example, and not to be limited to
these examples, the percussion therapy usually employs 1-7 beats
per second (i.e. 1-7 hertz) and the vibration therapy employs 7 to
25 beats per second (i.e. 7-25 hertz). The percussion mechanism 38
may employ mechanical fingers or rollers to impart the percussion
motion, but preferably comprises a pair of inflatable percussion
bladders 39, best shown in FIG. 3, having fingerlike cells that
oscillate between inflated and deflated states to provide the
percussive movement required. Such a mechanism is illustrated in
U.S. Patent Application Publication No. 2004/0193078 to Flick et
al., previously referenced.
[0030] Preferably, a rotation mechanism 40 of the rotation device
88 for rotation therapy is positioned below the percussion
mechanism 38. The rotation mechanism 40 provides rotation therapy
to the patient by rotating the patient from side to side. Along
with percussion and percussion-vibration therapy, rotation therapy
assists in reducing bed sores and pulmonary problems of the
patient. The rotation mechanism 40 is preferably a pair of
longitudinally positioned rotation bladders 42, shown in FIG. 3 and
described in the '078 publication to Flick et al. The rotation
bladders 42 are independently inflated and deflated to raise one
side of the patient, lower the patient, and then raise the other
side of the patient such that the patient experiences a
side-to-side rotation that shifts pressures between the patient and
the bladder 36 of the firmness setting device 84 of the mattress
20.
[0031] Referring to FIGS. 3 and 4, the low air loss mechanism 26 of
the mattress 20 used in conjunction with the encapsulating yet
permeable cover 24 is preferably positioned inward of the cover 24.
In operation, air is pumped from the low air loss mechanism 26
through the permeable cover 24 to reduce the temperature below the
patient support surface 22 and decrease the chance of skin
maceration that lowers the risk of bed sores. Preferably, the main
pump 50 delivers pressurized air to the perforated tubing of the
mechanism 26 disposed within the frame 34 and under the cover 24.
The tubing is external to the main air bladder 36, the percussion
mechanism 38, and the rotation mechanism 40.
[0032] Referring specifically to FIG. 2, a first control unit 46 of
a main control system 70 in the form of a rigid box and preferably
not of the mattress 20 is shown adjacent to a foot end 48 of the
mattress 20. The first control unit 46 encloses the main pump 50
and a power circuit board 52 of a main control system 70 for
operating the main pump 50 and transferring power to the rest of
the mattress components generally located in a second control unit
54. As shown, the first control unit 46 fits neatly below the foot
end 48 of the mattress 20, but is not incorporated within the cover
24 of the mattress 20. Of course, other configurations with the
first control unit 46 inside the cover 24 are also possible. Such
configurations are illustrated in the '078 publication to Flick et
al. In a preferred embodiment, the main pump 50 is used to inflate
the main air bladder 36, the percussion bladders 39, and the
rotation bladders 42, and to convey air to the perforated tube
26.
[0033] The second control unit 54 of the main control system 70 in
the form of a rigid box is shown beneath the cover 24 of the
mattress 20 within the perimeter of the frame 34 (see FIG. 2). The
second control unit 54 encloses the low air loss control system 56
for controlling the low air loss mechanism 26, the main valve
system 58 for inflating and deflating the main air bladder 36, the
percussion control system 60 for controlling the percussion
mechanism 38, the rotation control system 62 for controlling the
rotation mechanism 40, and a main circuit board 64 in operative
communication with these systems and the power circuit board 52 of
the first control unit 46. The second control unit 54 also
preferably encloses a processor 74 and memory 78 of the controller
72 for controlling operation of these systems 56, 58, 60, 62 and
the main pump 50. These systems 56, 58, 60, 62 may comprise motors,
solenoid valves, and/or motor-controlled valves, as disclosed in
the '078 publication. It should be appreciated that each of these
separate control systems 56, 58, 60, 62 may also represent portions
of a larger system. Those skilled in the art will now recognize
that the systems employed for controlling operation of the loss air
loss mechanism 26, main air bladder 36, percussion mechanism 38,
and rotation mechanism 40 may assume a variety of
configurations.
[0034] Referring to FIG. 4, the main control system 70 of the
patient support apparatus 10 is schematically illustrated. The main
control system 70 includes the controller 72 which comprises the
processor 74, the touch-screen display 32, a display driver 76 for
driving the touch-screen display 32, the memory 78, and a
communication interface 80. The controller 72, via communication
interfaces 80, is also in operative communication with the low air
loss control system 56, main valve system 58, percussion control
system 60, rotation control system 62, and the main pump 50.
[0035] Referring to FIG. 5, an air flow schematic of the patient
support apparatus 10 is shown. The air flow schematic generally
shows the movement of air through conduits from an air source 94
(preferably outside air at atmospheric pressure) via the main pump
50 to the second control unit 54 and more specifically, to the low
air loss control system 56, the main valve system 58, the
percussion control system 60, and the rotation control system 62.
Each of these systems 56, 58, 60, 62 preferably comprises valve
controls for operating their respective mechanisms, i.e., the
perforated tube 26, the main air bladder 36, the percussion
bladders 39, and the rotation bladders 42. Such valve controls are
described in more detail in the previously referenced '078
publication to Flick et al. herein incorporated by reference. It
should be appreciated that each of the separate control systems 56,
58, 60, 62 may be portions of a larger valve system, or the control
systems 56, 58, 60, 62 may represent direct connections between the
main pump 50 and the respective perforated tube 26 or bladders 36,
39, 42.
[0036] With further regards to the percussion device 86 and more
specific to the present invention, FIG. 6 illustrates the
percussion device 86 having the previously described percussion
control system 60 and the percussion mechanism 38. Referring to
FIG. 7, the percussion mechanism 38 also has a resonating pad 100
located between the main bladder 36 and the percussion bladders 39,
and a sensor 102 preferably being a pressure transducer located in
preferably each percussion bladder 39 for sensing air pressure.
Referring to FIG. 12, the resonating pad 100 is made of a
resiliently flexible material having at least one known natural
resonant frequency 104 that theoretically has a corresponding
amplitude (displacement) that extends to infinity. The natural
resonant frequency 104 is of the pad 100 when in an unloaded state
(i.e. no patient weight) and as best illustrated by the solid
amplitude vs. frequency curve 106 of FIG. 12.
[0037] In operation, and assuming no patient load is placed upon
the resonating pad 100 of mechanism 38, (see FIG. 12), the
percussion device 68 inflates and deflates the plurality of
bladders 39 at a baseline operating frequency 108 for optimal
energy efficiency. In order to substantially reduce wear and
potential damage of the device 86 via excessive vibration amplitude
or displacement, the baseline operating frequency 108 is close to
but is not at the resonant frequency 104 of the pad 100. Generally,
the baseline operating frequency 108 of the percussion device 86 is
slightly less than any chosen one of the at least one resonant
frequencies 104. To optimize percussion therapy, the material and
size of the resonating pad 100 is chosen with consideration made to
the range of weight distributions of the patient that will tend to
shift the amplitude vs. frequency curve 106. This shift or addition
of compressive weight on the resonating pad 100 generally alters
the resonating frequencies of the pad 100 and is best illustrated
as the shifted curve 110 having shifted resonating frequencies 112
in FIG. 12.
[0038] For ease of explanation, each bladder 39 has a pressure
transducer 102, thus each bladder 39 can react to weight changes of
the respective overhead portion of the patient. However, one
skilled in the art would now know that a plurality of bladders 39
could be controlled by one pressure transducer 102. If, for
instance possibly due to manufacturing cost, only one pressure
transducer 102 is utilized, its optimal location would be toward
the center of the mattress 22 or under the lungs of the patient
since percussion therapy is primarily used for treatment of the
lungs.
[0039] In operation of the percussion device 86 with the weight of
a patient on the mattress 22, the variable speed air pump 50
operates through the percussion control system 60 that preferably
includes a double diaphragm valve system 99 for controlled
inflation and deflation of the percussion bladders 39. The
inflation of the percussion bladders 39 by the pump 50 is
oscillated such that the pressure in the percussion bladders 39 is
increased and decreased, thereby lifting and dropping the patient.
The weight of the patient not only shifts the resonating frequency
to curve 110 but also adds a biasing force against the percussion
bladders 39 preferably distributed through the pad 100. This force
correlates with a pressure increase in the percussion bladders 39.
The pressure inside the percussion bladders 39 is continuously
monitored by the pressure transducers 102 and communicated to the
controller 72. As the speed of the pump 50 is changed, the pressure
inside the percussion bladders 39 created by patient's potentially
changing weight is monitored by the controller 72 to continually
adjust for an optimal operating frequency 114 that correlates to a
maximum pressure (pressure correlates to force divided by area, and
area correlates to amplitude). The controller 72 then operates the
pump 50 to achieve the optimal frequency 114 for percussion therapy
for that particular patient.
[0040] Referring to FIG. 8, a second embodiment of a mattress 22'
is illustrated. In the second embodiment, the resonating pad 100 of
the first embodiment is generally omitted. The percussion device
84' of the second embodiment operates similarly to the first
embodiment except that the main air bladder 36' also functions as
the resonating pad of the first embodiment, hence, it is the
resonating frequency of the bladder 36' that is generally monitored
indirectly by the pressure sensors 102'. As best illustrated in
FIG. 9, a third embodiment of a mattress 22'' is illustrated that
is similar to the second embodiment except that a main cushioning
member 36'' of the mattress 22'' is not a bladder but a generally
homogeneous and passive cushion preferably having a known natural
resonating frequency.
[0041] Referring to FIG. 10, a fourth embodiment of a mattress
22''' is illustrated wherein the sensors 102 of the first
embodiment are generally replaced with accelerometers 102''' of the
fourth embodiment. The accelerometers 102''' are positioned to
measure displacement of a resonating pad 100''' that directly
corresponds to amplitude of vibration and/or percussion. Referring
to FIG. 11, a fifth embodiment of a mattress 22'''' is illustrated
that is similar to the fourth embodiment except that a main
cushioning member 36'''' of the mattress 22'''' is not a bladder
but is a generally homogeneous and passive cushioning member 36''''
preferably having a known natural resonating frequency. In the
fifth embodiment, the accelerometer 102'''' is preferably located
in the cushioning member 36''''.
[0042] While the forms of the invention herein disclosed constitute
presently preferred embodiments, many others are possible. It is
not intended herein to mention all the possible equivalent forms or
ramifications of the invention. It is understood that the terms
used herein are merely descriptive rather than limiting, and that
various changes may be made without departing from the spirit or
scope of the invention. For instance, the term mattress as applied
to mattress 20 is not meant to be limited to a patient's bed, but
may apply to any pad assembly that supports all or any portion of a
patient against the bias of gravitational forces and whether or not
the patient is intended to actual sleep upon the mattress or pad
assembly.
[0043] In light of the present invention, one skilled in the art
would now realize that the bladder 36 may be a passive cushioning
member thus generally eliminating the firmness setting device 84
altogether. Such a the cushioning member 36 could be a soft pad
and/or made of a homogeneous material similar to the foam or gel of
the frame 34. Moreover, the air pump 50 and associated conduits
could be replaced with a temperature controlled fluid pump system
or a central pump system capable of handling a plurality of
beds.
* * * * *