Patent Description:
It also is known in the art to enclose such a bladder within an envelope, the envelope including a lower panel below the overlay bladder and an upper panel above the bladder. In some instances, the upper and lower panels of the envelope are imperforate. In others, at least one of the upper and lower panels (usually the upper panel) is perforated to allow pressurized air to flow from within the envelope to outside the envelope, thereby providing ventilating air to the body of a user thereon.

A drawback to such an arrangement is that the bladder may be loosely enclosed within the envelope so that at least one panel of the envelope is prone to shifting laterally with respect to the overlay when the assembly is manipulated, particularly with a patient or other user disposed thereon. This can lead to bunching or wrinkling of the panel(s) of the envelope, thereby creating pressure points adversely affecting patient comfort and the efficacy of the overlay. Alternatively or additionally, the bladder may shift or bunch up within the envelope, also thereby creating pressure points adversely affecting patient comfort and the efficacy of the overlay.

<CIT> discloses an air bed with alternating thickness and independently inflatable chambers. <CIT> discloses a person support apparatus with a foam core and a suction source that can evacuate air from the apparatus to compress the foam.

<CIT> discloses an apparatus for supporting a patient with the features of the preamble of claim <NUM>.

It would be desirable to control such shifting of the panel(s) of the envelope and shifting of the bladder therein.

The present invention solves this problem with a support system having the features of claim1. The disclosure shows and describes illustrative embodiments of a system configured and operable to do so.

The drawings show an illustrative embodiment of a system including a support surface overlay <NUM> having a bladder <NUM> and an envelope <NUM> containing the bladder <NUM>. The system also includes a control system <NUM> configured to selectively pressurize the bladder <NUM> and withdraw air from the envelope <NUM>, as will be discussed further below.

The bladder <NUM> includes a first (or upper) flat, flexible sheet <NUM> overlying a second (or lower) flat, flexible sheet <NUM>. One or both of the first and second sheets <NUM>, <NUM> may be imperforate. The first and second sheets <NUM>, <NUM> are joined together by a generally sinusoidal seam <NUM>, thereby defining first and second interdigitated inflatable compartments <NUM>, <NUM>. As best shown in <FIG>, the seam <NUM> may define one or more relief cuts <NUM>, for example, as further described in <CIT>.

The first and second compartments <NUM>, <NUM> may be selectively and independently inflated and deflated. The first compartment <NUM> may define a first plurality of inflatable cells <NUM> arranged in rows, each of the first plurality of inflatable cells <NUM> defining a corresponding contact node <NUM> when inflated. The second compartment <NUM> may define a second plurality of inflatable cells <NUM> arranged in rows interdigitated with the rows of the first plurality of inflatable cells <NUM>, each of the second of inflatable cells <NUM> defining a corresponding contact node <NUM> when inflated. As best shown in <FIG> and <FIG>, the rows of first and second inflatable cells <NUM>, <NUM> may extend in a side-to-side direction of the overlay <NUM>. In other embodiments, the rows of first and second inflatable cells <NUM>, <NUM> may extend in an end-to-end direction of the overlay <NUM>, perpendicular to that shown. In further embodiments, the rows of first and second inflatable cells <NUM>, <NUM> could extend in other directions.

In other embodiments, the bladder <NUM> could take any number of alternative forms.

A first bladder tube <NUM> defining a lumen therethrough extends from the first compartment <NUM> in fluid communication therewith. A second bladder tube <NUM> defining a lumen therethrough extends from the second compartment <NUM> in fluid communication therewith. The first and second bladder tubes <NUM>, <NUM> are joined or otherwise connected to one or both of the first and second sheets <NUM>, <NUM> in sealed engagement therewith. The free ends of the first and second bladder tubes <NUM>, <NUM> are configured for connection to the control system <NUM>, for example, via an intervening connector <NUM>, as will be discussed further below.

The envelope <NUM> includes a first (or upper) flexible panel <NUM> overlying a second (or lower) flexible panel <NUM>. (In <FIG> and <FIG>, the upper panel <NUM> is shown as being transparent for clarity. ) The first and second panels <NUM>, <NUM> are joined together by at least one generally circumferential seam <NUM>, thereby defining an interior region <NUM> of the envelope. The first and second panels <NUM>, <NUM> of the envelope <NUM> may be joined together directly. Alternatively, the first and second panels <NUM>, <NUM> of the envelope <NUM> may be joined together through an intervening structure. For example, the first panel <NUM> of the envelope <NUM> may be joined to the first sheet <NUM> of the bladder <NUM> by a seam <NUM>, and the second panel <NUM> of the envelope <NUM> may be joined to the second sheet <NUM> of the bladder <NUM> by the seam <NUM> or another seam.

One or both of the first and second panels <NUM>, <NUM> of the envelope <NUM> are made of flat, flexible sheets of material. One or both of the first and second sheets are imperforate or sufficiently imperforate that a vacuum may be drawn upon the interior region <NUM> thereof, as will be discussed further below.

The first and second panels <NUM>, <NUM> may be configured so that the first panel <NUM> stretches elastically to a greater degree than does the second panel <NUM> when the first panel <NUM> and the second panel <NUM> are subjected to the same or similar tensile load, as will be discussed further below. To this end, the first and second panels <NUM>, <NUM> could be made of different materials having different material properties, or they could be made of the same material of different thicknesses, or both. In an embodiment, the first panel <NUM> is substantially thinner than the second panel <NUM>, for example, half the thickness of the second panel <NUM>, so that the first panel <NUM> stretches elastically to a greater degree than does the second panel <NUM> when the first panel <NUM> and the second panel <NUM> are subjected to the same or similar tensile load. In other embodiments, the envelope <NUM> could take any number of alternative forms.

An envelope tube <NUM> defining a lumen therethrough extends from the interior region <NUM> in fluid communication therewith. The envelope tube <NUM> is joined or otherwise connected to either or both of the first and second panels <NUM>, <NUM> in sealed engagement therewith. The envelope tube <NUM> includes an optional in-line envelope filter <NUM> configured to capture biohazardous material that may be present in the interior region <NUM> of the envelope <NUM> and mitigate a likelihood of such biohazardous material from contaminating the controller <NUM>. The envelope tube <NUM> also includes an in-line calibrated envelope check valve <NUM> outboard of the optional in-line envelope filter <NUM>, and configured to preclude undesired entry of air from atmosphere to the interior region <NUM> of the envelope <NUM>. In other embodiments, the locations of the in-line calibrated envelope check valve <NUM> and the optional in-line envelope filter <NUM> could be reversed with respect to each other. The free end of the envelope tube <NUM> is configured for connection to the control system <NUM>, for example, via an intervening connector <NUM>, as will be discussed further below.

The control system <NUM> is operable to selectively and independently force pressurized air (or another medium) into, and relieve the air (or other medium) from, the first and second compartments <NUM>, <NUM> to selectively and independently inflate and deflate the corresponding inflatable cells <NUM>, <NUM> through the first and second bladder tubes <NUM>, <NUM>. The control system <NUM> also is operable to selectively withdraw air (or another medium) from the interior region <NUM> of the envelope <NUM> to selectively collapse the first and second panels <NUM>, <NUM> of the envelope <NUM> against the first and second sheets <NUM>, <NUM> of the bladder <NUM> within the envelope <NUM>.

As shown in <FIG>, the control system <NUM> includes a pump <NUM>, which may be a pneumatic pump. The control system <NUM> also includes a pneumatic circuit including a valve or manifold arrangement configured to selectively align the suction of the pump <NUM> in fluid communication with the interior region <NUM> of the envelope <NUM>, and to selectively align the discharge of the pump <NUM> in fluid communication with one or both of the first and second inflatable compartments <NUM>, <NUM> of the bladder <NUM>.

More specifically, the pneumatic circuit includes a pump input (or suction) line <NUM> in selective fluid communication with an input (or suction) port of the pump <NUM>. The pump suction line <NUM> also is in selective fluid communication with the atmosphere via a calibrated vacuum relief valve <NUM>. The calibrated vacuum relief valve <NUM> is in parallel with the calibrated envelope check valve <NUM>. A filter <NUM> may be provided on the side of the calibrated vacuum relief valve <NUM> opposite the pump <NUM> to filter air drawn from the atmosphere into the controller <NUM>.

The calibrated vacuum relief valve <NUM> is configured to be closed when the pressure in the suction line <NUM> is at or above a predetermined suction line pressure (which may be referred to herein as the calibrated vacuum relief valve setpoint pressure), and to open when the pressure in the suction line <NUM> is below the predetermined suction line pressure.

The pneumatic circuit also includes a pump output (or pressure) line <NUM> in selective fluid communication with an output (or pressure) port of the pump <NUM>. The pump pressure line <NUM> is in selective fluid communication with the first inflatable compartment <NUM> of the bladder <NUM> via the first bladder tube <NUM> and an intervening, three-way, first compartment isolation valve <NUM>. The first compartment isolation valve <NUM> is power-operated, for example, solenoid-operated. Also, the first inflatable compartment <NUM> of the bladder <NUM> is in selective fluid communication with the atmosphere through an air outlet <NUM> via the first bladder tube <NUM> and the intervening first compartment isolation valve <NUM>. With the first compartment isolation valve <NUM> in a first position, the first inflatable compartment <NUM> of the bladder <NUM> is in fluid communication with the pump pressure line <NUM> and not with the atmosphere. With the first compartment isolation valve <NUM> in a second position, the first inflatable compartment <NUM> of the bladder <NUM> is in fluid communication with the atmosphere and not with the pump pressure line <NUM>. A first inflatable compartment pressure sensor <NUM> is configured to sense pressure in a pneumatic line connecting the first inflatable compartment <NUM> to the first inflatable compartment isolation valve <NUM>.

Similarly, the pump pressure line <NUM> is in selective fluid communication with the second inflatable compartment <NUM> of the bladder <NUM> via the second bladder tube <NUM> and an intervening, three-way, second compartment isolation valve <NUM>. The second compartment isolation valve <NUM> is power-operated, for example, solenoid-operated. Also, the second inflatable compartment <NUM> of the bladder <NUM> is in selective fluid communication with the atmosphere through an air outlet <NUM> via the second bladder tube <NUM> and the intervening second compartment isolation valve <NUM>. With the second compartment isolation valve <NUM> in a first position, the second inflatable compartment <NUM> of the bladder <NUM> is in fluid communication with the pump pressure line <NUM> and not with the atmosphere. With the second compartment isolation valve <NUM> in a second position, the second inflatable compartment <NUM> of the bladder <NUM> is in fluid communication with the atmosphere and not with the pump pressure line <NUM>. A second inflatable compartment pressure sensor <NUM> is configured to sense pressure in a pneumatic line connecting the second inflatable compartment <NUM> to the second inflatable compartment isolation valve <NUM>.

As suggested above, one or more pneumatic connectors <NUM> may be provided to facilitate connection and disconnection of the control system <NUM> pneumatic lines to and from the first bladder tube <NUM>, the second bladder tube <NUM>, and the envelope tube <NUM> of the bladder <NUM>.

The control system <NUM> includes a controller <NUM> configured to receive inputs from a user interface panel <NUM>, to receive inputs from the first inflatable compartment pressure sensor <NUM>, and from the second inflatable compartment pressure sensor <NUM>. The controller <NUM> also is configured to provide control outputs to the pump <NUM>, to the first compartment isolation valve <NUM>, and to the second compartment isolation valve <NUM> to thereby selectively turn the pump <NUM> on and off and to selectively change the states of the first compartment isolation valve <NUM> and the second compartment isolation valve <NUM> valve between respective open and closed positions, as will be discussed further below.

The user interface panel <NUM> may include user input devices, for example without limitation, sensors, switches, touchscreens, and the like, enabling user control of the control system <NUM> and/or components thereof. The user input devices may be operable to enable user control of any number of system functions, for example, on/off, cycle time, cycle programs, and inflatable compartment pressures, among others. The controller <NUM> may selectively cause the pump <NUM> to turn on and off based on any or all of user input from the user input devices, input from hardware or software resident in the controller <NUM> or elsewhere, and input from the first inflatable compartment pressure sensor <NUM> and the second inflatable compartment pressure sensor <NUM>. Also, the controller <NUM> may be configured to selectively effect various alignments of the first compartment isolation valve <NUM> and the second compartment isolation valve <NUM> valve between respective open and closed positions, as will be discussed further below.

As mentioned above, the control system <NUM> is operable to selectively provide pressurized air to the first and second compartments <NUM>, <NUM> of the bladder <NUM> to thereby inflate and deflate the first and second compartments <NUM>, <NUM>. More specifically, the control system <NUM> is configured to selectively provide pressurized air to, and relieve pressurized air from, the first and second compartments <NUM>, <NUM>. The control system <NUM> may provide pressurized air to either or both of the first and second compartments <NUM>, <NUM> at the same time or alternatingly, and to relieve pressurized air from either or both of the first and second compartments <NUM>, <NUM> at the same time or alternatingly. As such, at any time, both of the first and second compartments <NUM>, <NUM> may be fully or partially inflated at the same time, both of the first and second compartments <NUM>, <NUM> may be fully or partially deflated at the same time, one of the first and second compartments <NUM>, <NUM> may be fully or partially inflated while the other is fully or partially deflated, both of the first and second compartments <NUM>, <NUM> may be becoming inflated at the same time, both of the first and second compartments <NUM>, <NUM> may be becoming deflated at the same time, one of the first and second compartments <NUM>, <NUM> may be becoming inflated while the other is becoming deflated, and so on. The control system <NUM> may be operable to selectively pressurize the first and second compartments <NUM>, <NUM> as desired to any one or more predetermined pressures.

The control system <NUM> also is operable to selectively withdraw air from the interior region <NUM> of the envelope <NUM> independent of any inflation and/or deflation of the first and second compartments <NUM>, <NUM> of the bladder <NUM>. More specifically, the control system <NUM> is configured to selectively withdraw air from the interior region <NUM> of the envelope <NUM>, thereby causing the first and second panels <NUM>, <NUM> of the envelope to collapse against and conform to the bladder <NUM> to varying extents, as will be discussed further below. With the first and second panels <NUM>, <NUM> of the envelope collapsed against the bladder <NUM>, lateral (that is, end-to-end and side-to-side) motion of the bladder <NUM> with respect to the envelope <NUM>, with respect to a user disposed thereon, and/or with respect to a support surface (for example, a hard surface or a foam or other flexible and resilient underlayment) upon which the bladder is disposed is inhibited or substantially eliminated.

For example, the control system <NUM> is operable in a first mode of operation to vent both of the first inflatable compartment <NUM> and the second inflatable compartment <NUM> to atmosphere. In the first mode of operation, the control system <NUM> may or may not draw a vacuum on the interior region <NUM> of the envelope <NUM>, as will be discussed further below. In the first mode of operation, the first compartment isolation valve <NUM> is in its second position so that the first inflatable compartment <NUM> is vented to the atmosphere through the air outlet <NUM> and isolated from the pump <NUM>. Similarly, the second compartment isolation valve <NUM> is in its second position so that the second inflatable compartment <NUM> is vented to the atmosphere through the air outlet <NUM> and isolated from the pump <NUM>. The pump <NUM> may or may not be running. If the pump <NUM> is running, the pump <NUM> draws a vacuum on the interior region <NUM> of the envelope <NUM> via the pump suction line <NUM>. The first and second inflatable compartments <NUM>, <NUM> may be de-pressurized or evacuated more quickly with the pump <NUM> running than with the pump <NUM> not running. If the pressure in the pump suction line <NUM> drops below the calibrated vacuum relief valve set point pressure, the calibrated vacuum relief valve <NUM> opens, thereby coupling the suction of the pump <NUM> to the atmosphere through the calibrated vacuum relief valve <NUM> and the filter <NUM>. Because the first compartment isolation valve <NUM> and the second compartment isolation valve <NUM> are in their second positions, thereby isolating the pump <NUM> from the first inflatable compartment <NUM> and the second inflatable compartment <NUM>, respectively, the discharge of the pump <NUM> is routed to the atmosphere via the calibrated pressure relief valve <NUM> once the pressure in the pump output line <NUM> upstream of the first and second compartment isolation valves <NUM>, <NUM> exceeds the calibrated pressure relief valve setpoint pressure.

The control system <NUM> is operable in a second mode of operation to inflate and pressurize the first inflatable compartment <NUM>, vent the second inflatable compartment <NUM> to atmosphere, and draw a vacuum on the interior region <NUM> of the envelope <NUM>. In the second mode of operation, the first compartment isolation valve <NUM> is in its first position so that the first inflatable compartment <NUM> is in fluid communication with the outlet of the pump <NUM> via the pump output line <NUM> and isolated from the atmosphere. The second compartment isolation valve <NUM> is in its second position so that the second inflatable compartment <NUM> is vented to the atmosphere through the air outlet <NUM> and isolated from the pump <NUM>. In the second mode of operation, the pump <NUM> is running, thereby inflating and pressurizing the first inflatable compartment <NUM> with air discharged from the pump <NUM> via the pump discharge line <NUM> and the first compartment isolation valve <NUM>. When the pressure in the pneumatic line connecting the first compartment isolation valve <NUM> to the first inflatable compartment <NUM> exceeds a predetermined pressure, as may be sensed by the first inflatable compartment pressure sensor <NUM>, the controller <NUM> may cause the pump <NUM> to turn off. If the pressure in the pump output line <NUM> upstream of the first and second compartment isolation valves <NUM>, <NUM> exceeds the calibrated pressure relief valve setpoint pressure, the calibrated pressure relief valve <NUM> opens, thereby venting the pump discharge line <NUM> upstream of the first and second compartment isolation valves <NUM>, <NUM> to the atmosphere. Also, the pump <NUM> draws a vacuum on the interior region <NUM> of the envelope <NUM> via the pump suction line <NUM>. If the pressure in the pump suction line <NUM> drops below the calibrated vacuum relief valve set point pressure, the calibrated vacuum relief valve <NUM> opens, thereby coupling the suction of the pump <NUM> to the atmosphere through the calibrated vacuum relief valve <NUM> and the filter <NUM>.

The control system is operable in a third mode of operation to vent the first inflatable compartment <NUM> to atmosphere, inflate and pressurize the second inflatable compartment <NUM>, and draw a vacuum on the interior region <NUM> of the envelope <NUM>. In the third mode of operation, the first compartment isolation valve <NUM> is in its second position so that the first inflatable compartment <NUM> is vented to the atmosphere through the air outlet <NUM> and isolated from the pump <NUM>. The second compartment isolation valve <NUM> is in its first position so that the second inflatable compartment <NUM> is in fluid communication with the outlet of the pump <NUM> via the pump output line <NUM> and isolated from the atmosphere. In the second mode of operation, the pump <NUM> is running, thereby inflating and pressurizing the second inflatable compartment <NUM> with air discharged from the pump <NUM> via the pump discharge line <NUM> and the second compartment isolation valve <NUM>. When the pressure in the pneumatic line connecting the second compartment isolation valve <NUM> to the second inflatable compartment <NUM> exceeds a predetermined pressure, as may be sensed by the second inflatable compartment pressure sensor <NUM>, the controller <NUM> may cause the pump <NUM> to turn off. If the pressure in the pump output line <NUM> upstream of the first and second compartment isolation valves <NUM>, <NUM> exceeds the calibrated pressure relief valve setpoint pressure, the calibrated pressure relief valve <NUM> opens, thereby venting the pump discharge line <NUM> upstream of the first and second compartment isolation valves <NUM>, <NUM> to the atmosphere. Also, the pump <NUM> draws a vacuum on the interior region <NUM> of the envelope <NUM> via the pump suction line <NUM>. If the pressure in the pump suction line <NUM> drops below the calibrated vacuum relief valve set point pressure, the calibrated vacuum relief valve <NUM> opens, thereby coupling the suction of the pump <NUM> to the atmosphere through the calibrated vacuum relief valve <NUM> and the filter <NUM>.

The control system <NUM> is operable in a fourth mode of operation to inflate and pressurize both the first inflatable compartment <NUM> and the second inflatable compartment <NUM>, and to draw a vacuum on the interior region <NUM> of the envelope <NUM>. In the fourth mode of operation, the first compartment isolation valve <NUM> is in its first position so that the first inflatable compartment <NUM> is in fluid communication with the outlet of the pump <NUM> via the pump output line <NUM> and isolated from the atmosphere. The second compartment isolation valve <NUM> is in its first position so that the second inflatable compartment <NUM> is in fluid communication with the outlet of the pump <NUM> via the pump output line <NUM> and isolated from the atmosphere. In the fourth mode of operation, the pump <NUM> is running, thereby inflating and pressurizing the first inflatable compartment <NUM> with air discharged from the pump <NUM> via the pump discharge line <NUM> and the first compartment isolation valve <NUM>, and thereby inflating and pressurizing the second inflatable compartment <NUM> with air discharged from the pump <NUM> via the pump discharge line <NUM> and the second compartment isolation valve <NUM>. When the pressure in the pneumatic line connecting the first compartment isolation valve <NUM> to the first inflatable compartment <NUM> exceeds a predetermined pressure and the pressure in the pneumatic line connecting the second compartment isolation valve <NUM> to the second inflatable compartment <NUM> exceeds a predetermined pressure, the controller <NUM> may cause the pump <NUM> to turn off. If the pressure in the pump output line <NUM> upstream of the first and second compartment isolation valves <NUM>, <NUM> exceeds the calibrated pressure relief valve setpoint pressure, the calibrated pressure relief valve <NUM> opens, thereby venting the pump discharge line <NUM> upstream of the first and second compartment isolation valves <NUM>, <NUM> to the atmosphere. Also, the pump <NUM> draws a vacuum on the interior region <NUM> of the envelope <NUM> via the pump suction line <NUM>. If the pressure in the pump suction line <NUM> drops below the calibrated vacuum relief valve set point pressure, the calibrated vacuum relief valve <NUM> opens, thereby coupling the suction of the pump <NUM> to the atmosphere through the calibrated vacuum relief valve <NUM> and the filter <NUM>.

The control system <NUM> may be operable to selectively inflate the first and second inflatable compartments <NUM>, <NUM>, to any desired pressures, for example, any pressures between <NUM> Pa or less and <NUM> Pa or more (one psi or less and fifteen psi or more), including but not limited to (<NUM> psi = <NUM> Pa) <NUM> psi, <NUM> psi, <NUM> psi, <NUM> psi, <NUM> psi, <NUM> psi, <NUM> psi, <NUM> ps, <NUM> psi, <NUM> psi, <NUM> psi, <NUM> psi, <NUM> psi, <NUM> psi, <NUM> psi, <NUM> psi, <NUM> psi, <NUM> psi, <NUM> psi, <NUM> psi, <NUM> psi, <NUM> psi, <NUM> psi, <NUM> psi, <NUM> psi, <NUM> psi, <NUM> psi, <NUM> psi, and <NUM> psi, and any intervening pressures. Any or all of the capacity of the pump <NUM>, the setpoint pressures of the first and second pressure sensors <NUM>, <NUM>, the calibrated pressure relief valve setpoint, and operational parameters of the controller <NUM> may be varied to select the desired pressures.

The control system <NUM> may be operable to control the proportion of air withdrawn from the interior region <NUM> of the envelope <NUM> (compared to, for example, the maximum volume of the envelope <NUM>), thereby controlling the degree of collapse of the panels <NUM>, <NUM> of the envelope <NUM> against the bladder <NUM>. Any or all of the capacity of the pump <NUM>, the calibrated vacuum relief valve setpoint, and operational parameters of the controller <NUM> may be varied to select the desired proportion of air withdrawn from the interior region <NUM> of the envelope <NUM> and the degree of collapse of the panels <NUM>, <NUM> of the envelope <NUM> against the bladder <NUM>.

<FIG> show the bladder <NUM> and envelope <NUM> in various states of inflation and vacuum, respectively.

<FIG> shows the bladder <NUM> with both of the first and second inflatable compartments <NUM>, <NUM> fully deflated, and the interior region <NUM> of the envelope <NUM> at atmospheric pressure. The first and second panels <NUM>, <NUM> are shown exaggeratedly spaced from the bladder <NUM> for clarity.

<FIG> shows the bladder <NUM> with the first inflatable compartment <NUM> fully inflated, and the interior region <NUM> of the envelope <NUM> at atmospheric pressure. The first and second panels <NUM>, <NUM> are shown exaggeratedly spaced from the bladder <NUM> for clarity.

<FIG> shows the bladder <NUM> with both of the first and second inflatable compartments <NUM>, <NUM> fully inflated, and the interior region <NUM> of the envelope <NUM> at atmospheric pressure. The first and second panels <NUM>, <NUM> are shown exaggeratedly spaced from the bladder <NUM> for clarity.

<FIG> shows the bladder <NUM> with the first inflatable compartment <NUM> fully inflated, and a partial vacuum drawn on the interior region <NUM> of the envelope <NUM>. The first panel <NUM> of the envelope <NUM> conforms to the first inflatable cells <NUM> of the first inflatable compartment <NUM> to a first degree. The second panel <NUM> of the envelope <NUM> conforms to the first inflatable cells <NUM> of the first inflatable compartment <NUM> to a second degree less than the first degree. The first panel <NUM> of the envelope <NUM> conforms to the first inflatable cells <NUM> of the first inflatable compartment <NUM> to a greater degree than does the second panel <NUM> of the envelope <NUM> because the first panel <NUM> has greater elasticity than the second panel <NUM>, as discussed further above.

<FIG> shows the bladder <NUM> with both the first and second inflatable compartments <NUM>, <NUM> fully inflated, and a partial vacuum drawn on the interior region <NUM> of the envelope <NUM>. The first panel <NUM> of the envelope <NUM> conforms to the first inflatable cells <NUM> of the first inflatable compartment <NUM> and to the second inflatable cells <NUM> of the second inflatable compartment <NUM> to a first degree. The second panel <NUM> of the envelope <NUM> conforms to the first inflatable cells <NUM> of the first inflatable compartment <NUM> and to the second inflatable cells <NUM> of the second inflatable compartment <NUM> to a second degree less than the first degree. The first panel <NUM> of the envelope <NUM> conforms to the first and second inflatable cells <NUM>, <NUM> of the first and second inflatable compartment <NUM>, <NUM>, respectively, to a greater degree than does the second panel <NUM> of the envelope <NUM> because the first panel <NUM> has greater elasticity than the lower panel <NUM>, as discussed further above.

<FIG> shows the bladder <NUM> with the first inflatable compartment <NUM> fully inflated, and a greater vacuum drawn on the interior region <NUM> of the envelope <NUM> than represented in <FIG> and <FIG>. The first panel <NUM> of the envelope <NUM> conforms to the first inflatable cells <NUM> of the first inflatable compartment <NUM> to a first degree. The second panel <NUM> of the envelope <NUM> conforms to the first inflatable cells <NUM> of the first inflatable compartment <NUM> to a third degree. The third degree may be less than the first degree and greater than the second degree, or it may be substantially similar to the first degree. This phenomenon may occur because the relatively greater vacuum has greater effect on further collapsing the second panel <NUM> against the cells <NUM> of the bladder <NUM> (compared to the state represented in <FIG> and <FIG>) than it does on further collapsing the second panel <NUM> against the cells <NUM> of the bladder <NUM> (compared to the state represented in <FIG> and <FIG>). This phenomenon may be a consequence of relevant properties of the materials of which the first and second panels <NUM>, <NUM> are made and or the relative thicknesses of the first and second panels <NUM>, <NUM>.

<FIG> is similar to <FIG> but shows both the first and second panels <NUM>, <NUM> of the envelope more closely conforming to the first inflatable cells <NUM> of the bladder <NUM> because a still greater vacuum is drawn on the interior region <NUM> of the envelope <NUM>.

In some embodiments, the first panel <NUM> of the envelope <NUM> may have elasticity similar to that of the second panel <NUM> of the envelope <NUM>. In such embodiments, the first panel <NUM> of the envelope <NUM> could conform to the first inflatable cells <NUM> of the first inflatable compartment <NUM> to the same degree or a similar degree that the second panel <NUM> conforms to the first inflatable compartment <NUM> in the various states of operation as discussed above.

In modes of operation wherein one of the first and second inflatable compartments <NUM>, <NUM> is inflated and the other of the first and second inflatable compartments <NUM>, <NUM> is deflated, the upper and lower panels <NUM>, <NUM> of the envelope <NUM> would conform to the bladder <NUM> in manners similar to those described above during the various modes of operation as described above.

Claim 1:
A support system comprising: a bladder (<NUM>), the bladder (<NUM>) comprising: a first flexible sheet (<NUM>) and a second flexible sheet (<NUM>), the first and second flexible sheets bonded together at a seam (<NUM>), wherein the first (<NUM>) and second flexible sheets (<NUM>) and the seam (<NUM>) cooperate to define an inflatable compartment (<NUM>), the inflatable compartment (<NUM>) defining a plurality of inflatable cells (<NUM>), each of the plurality of inflatable cells (<NUM>) defining a corresponding contact node (<NUM>); an envelope (<NUM>) enclosing the bladder (<NUM>), the envelope (<NUM>) comprising a first sheet (<NUM>) and a second sheet (<NUM>) bonded to the first sheet (<NUM>), thereby defining an interior region (<NUM>) of the envelope (<NUM>); a pump (<NUM>); a valve system operable to enable fluid communication of an outlet (<NUM>) of the pump (<NUM>) with the inflatable compartment (<NUM>) or with an atmosphere surrounding the support system; and a controller operable to control valves of the valve system, characterized in that the inflatable compartment (<NUM>) and the plurality of inflatable cells (<NUM>) are selectively inflatable and the pump (<NUM>) is coupled in fluid communication with the interior region (<NUM>) of said envelope (<NUM>), the pump (<NUM>) configured to selectively remove air from the interior region (<NUM>) of the envelope (<NUM>) and thereby cause the first sheet (<NUM>) and the second sheet (<NUM>) of the envelope (<NUM>) to selectively conform to surfaces of the bladder (<NUM>) and the valve system is operable to enable selective fluid communication of an inlet (<NUM>) of the pump (<NUM>) with the interior region of the envelope (<NUM>).