Patent Publication Number: US-7219380-B2

Title: Multicompartmented air mattress

Description:
BACKGROUND OF THE INVENTION 
   1. The Field of the Invention 
   The present invention relates generally to an inflatable mattress and, more specifically, to a mattress having multiple, fluidly-unconnected chambers that can be selectively inflated and deflated to increase and decrease the pressure exerted from positions on the mattress surface on various points of contact with the human body. 
   2. The Relevant Technology 
   There is evidence that decubitus ulcers, otherwise known as pressure sores or bedsores, may develop when a bed-ridden person is not able to move. For example, people who are unconscious, unable to sense pain, paralyzed or otherwise unable to move can remain in the same location fostering the development of the bedsores. Bedsores are ugly, generally regarded as painful and typically debilitating. To reduce the incidence of bed sores, people in attendance to the bed-ridden person need to move or rotate the bed ridden person on a regular basis and in turn vary the parts of the body that are exposed to the pressure and reduce the risk of developing bed sores. Bed sores can be found on people/patients in hospitals, nursing homes and in homes under home care. Bedsores can lead to additional medical complications, including bone and blood infections, infectious arthritis, penetrating holes below the wound that burrow into bone or deeper tissues, and scar carcinoma, a form of cancer that develops in scar tissue. 
   Bedsores generally form at points of pressure, where the weight of the patient&#39;s body presses the skin against the firm surface of the bed. The skin&#39;s blood supply is believed to be interrupted or reduced by the pressure in turn causing injury to skin cells which can cause them to die. Unless the pressure is periodically is relieved to allow full blood flow to the pressed areas of the skin, the skin cells in the area start to die leading to ulcerations as the body seeks to deal with the cells. The ulcerations can grow into notable bed sores some in excess of the area of a quarter or half dollar. To allow blood to flow to the areas of restriction and reduce the risk of sores, attending personnel are typically tasked to regularly turn the patients. However, turning of patients as tasked does not always happen for reasons not pertinent here. 
   Bedsores are commonly found on or near the tail bone area, hips, back, elbows, heels and ankles. They can become deep, extending into the muscle. Muscle is even more prone to severe injury from pressure than skin. This means that mild injury to the skin may cover a deeper, more pronounced injury to muscle. Bedsores are extremely difficult to heal, unnecessary and can be prevented. It is much easier and cheaper to prevent a bed sore than to try and heal a bedsore. 
   Inflatable mattresses that are seen in the literature appear to be and are believed to be difficult to operate, expensive, and unreliable. In turn, it is understood that such have enjoyed only limited acceptance. An inflatable mattress that is easily usable for a patient or hospital bed that is reliable and easy to operate is not known. An inflatable mattress that varies the pressure in separate cells under different parts of the body and that accurately and promptly operates to maintain the pressure and then vary it in accordance with individual or preprogrammed instructions is also not known. 
   BRIEF SUMMARY OF THE INVENTION 
   A mattress system of the present invention includes multiple inflatable chambers, a pump, a valve assembly, a source of liquid (including gases like air), a sensor to detect the position of the inflatable chambers, a controller and interconnecting conduits. The multiple inflatable chambers are selectively inflatable and deflatable to vary the points of contact between the mattress surface and the patient&#39;s body. The inflatable mattress system of the present invention alternates, by the use of inflatable cells, the amount and location inflatable chamber pressure, thereby regulating the amount and location of mattress surface contact with a patient&#39;s body for a pre-selected period of time. Complications associated with pressure sores that result from constant contact between parts of the mattress surface and the body are thereby significantly reduced if not eliminated. 
   A system and method for selectively inflating and/or deflating a plurality of inflatable chambers of a mattress system is provided. The system includes a first plurality of inflatable chambers, each of which has at least one wall member forming an interior volume. The wall member is made from a flexible material selected to retain fluid. Each of the first plurality of inflatable chambers have a chamber connector for fluid communication with the interior volume. The wall member is deflectable between a first inflated position and a second inflated position that is different from the first inflated position. 
   The system and method also includes a number of deflectable resistors that predictably vary their respective electrical resistance upon deflection from a first configuration to a second configuration when applying an electrical signal thereto. Each of the deflectable resistors are attached to a wall member of an inflatable chamber to deflect therewith upon movement between the first inflated position and the second inflated position. The deflectable resistor generates a deflection signal reflective of said movement. A fluid source is provided for supplying a fluid under pressure into each interior volume of the first plurality of inflatable chambers. 
   The system and method further includes a first conduit means connected to the chamber connector for communicating fluid to and from the interior volume and a second conduit means connected to the fluid source for communicating fluid to and from the fluid source. A discharge means communicates fluid away from the inflatable mattress system from the interior volume. A valve is connected to the first conduit means, the second conduit means and the discharge means. The valve operates between a first position in which the valve places the first conduit means in communication with the second conduit means for supplying fluid from the fluid source to the interior volume and a second position in which the valve places the first conduit means in fluid communication with the discharge means. A controller is connected to each of the deflectable resistors for supplying an electrical signal and for receiving the deflection signal. The controller is connected to the valve and is configured to generate and supply operating commands for operating the valve between the first position and the second position. 
   In another embodiment, the inflatable mattress has a processor that is communicatively coupled to a controller. The processor has computer-executable instructions for performing a computer process for receiving a deflection signal, deriving an amount of movement from the deflection signal and directing a controller to deliver operating commands. 
   In another preferred embodiment, the valve is a valve assembly having a valve housing with an inlet for connecting said valve assembly to said fluid source. The valve assembly also includes a first valve plate having a first aperture and a second aperture. A second valve plate is also provided that has a plurality of outlet apertures. The second valve plate is coupled to the valve housing forming a fluid chamber. The outlet apertures are disposed at locations about the second valve plate so that the outlet apertures align with either the first aperture or the second aperture. A drive mechanism is connected to the first valve plate to rotate the first valve plate relative to the second valve plate. 
   In yet another preferred embodiment, the valve assembly has a three-way valve. The three-way valve is coupled to the fluid source and to the atmosphere. The three-way valve is configured for supplying the inflatable chambers with fluid from the fluid source and discharging the fluid from the inflatable chambers into the atmosphere. 
   In still another preferred embodiment, the valve assembly further comprises a pressure sensor for monitoring fluid pressure in each inflatable chamber. The pressure sensor takes a pressure reading within the inflatable chambers and transmits the pressure reading to a controller. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     To further clarify the above and other advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
       FIG. 1  illustrates a hospital bed apparatus using the inflatable mattress system of the present invention; 
       FIG. 2  illustrates an exploded perspective view of the inflatable mattress system; 
       FIG. 3  illustrates an alternate arrangement of an inflatable mattress system using several different sized inflatable chambers; 
       FIG. 4  illustrates a side view of an individual inflatable chamber; 
       FIG. 5  illustrates a bottom view of an individual inflatable chamber showing a fitting; 
       FIG. 6  illustrates a top view of an individual inflatable chamber showing the placement of a deflectable resistor; 
       FIG. 7  is a block diagram illustrating the electrical and mechanical elements for controlling the operation of the inflatable mattress system; 
       FIG. 8  illustrates a front view of the valve assembly; 
       FIG. 9  illustrates an exploded perspective view of the elements of the valve assembly; 
       FIG. 10  illustrates a top view of the first valve plate of the valve assembly; 
       FIG. 11  illustrates a side view of the first valve plate of the valve assembly; 
       FIG. 12  illustrates a top view of the second valve plate of the valve assembly; 
       FIG. 13  illustrates a side view of the second valve plate of the valve assembly; 
       FIG. 14  illustrates a top view of the valve housing of the valve assembly; 
       FIG. 15  illustrates a side view of the valve housing of the valve assembly. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The various exemplary embodiments provide an inflatable mattress having multiple, fluidly isolated inflatable chambers that can be selectively inflated and deflated to increase and decrease the pressure exerted from various points of the mattress surface on a human body. 
   Referring to  FIG. 1 , the inflatable mattress of a first embodiment is displayed in a typical hospital bed apparatus  10 . The two basic components of hospital bed apparatus  10  include a conventional hospital bed  15  and an inflatable mattress system  20  embodying the present invention. The inflatable mattress system  20  may be discussed here for use with a conventional hospital bed. However, any number of commercial applications that incorporate the mattress system of the present invention are possible including home, hospice, hotel, mobile home and RV to name a few. 
   Referring now to  FIG. 2 , an exploded structure of inflatable mattress system  20  is illustrated. Inflatable chamber enclosure  30  is a generally rectangular element having side walls  31 ,  32 , top end wall  33 , bottom end wall  34  and inflatable chamber dividers  35 ,  36   37 . Inflatable chamber dividers  35 ,  36  and  37  are disposed within inflatable chamber enclosure  30  at various locations to form the containment areas for a plurality of mattress cells or inflatable chambers  50 . 
   Inflatable chamber dividers  35 ,  36 ,  37  are placed generally at locations within enclosure  30  corresponding to the particular shape and size of the plurality of inflatable chambers  50  in a row or grouping. For example, interior region  46  of mattress system  20  is defined between top end wall  33 , a portion of side wall  31 , a portion of side wall  32  and cell divider  37 . As such, a grouping of plurality of mattress cells or inflatable chambers  50  would be located within the interior region  46  of mattress system  20 . Interior regions  47 ,  48 ,  49  are formed in a similar manner as interior region  46 . 
   Inflatable chamber cover  40  is generally a rectangular element having side walls  41 ,  42 , top end wall  43 , bottom end wall  44  and a removable lid  45 . Removable lid  45  is secured to top end wall  43  by any conventional means appropriate for the material used to manufacture inflatable chamber cover  40 . For example, if inflatable chamber cover  40  is manufactured using a fabric such as cotton, conventional sewing stitches may be used to secure removable lid  45  to top end wall  43 . Removable lid  45  is then secured to side walls  41 ,  42  and bottom end wall  43  with suitable fasteners such a zipper, snaps, or other coupling mechanism. (not shown). 
   A plurality of inflatable chambers  50 , designed to support the weight of a human body, are positioned within inflatable chamber enclosure  30 . In the illustrated embodiment, the mattress structure of inflatable mattress system  20  is sized as a twin mattress for use in a typical hospital bed. However, any mattress size (e.g. king, queen, or full) may be manufactured using the inflatable multi-cell design described herein without departing from the intended scope and spirit of the invention. 
   Inflatable chamber cover  40  is adapted to fit together with inflatable chamber enclosure  30 . The combination of inflatable chamber cover  40 , inflatable chamber enclosure  30  and plurality of inflatable chambers  50  forms the overall structure of the inflatable mattress. Removable lid  45  may be folded back to expose the plurality of inflatable chambers  50 . Thus, any inflatable chamber  50  within inflatable mattress system  20  may be easily replaced or repaired without having to compromise the overall structural integrity of mattress system  20 . The structure and design of inflatable chambers  50  are an important aspect of the present invention, and therefore, are described in greater detail in subsequent paragraphs. 
   Referring now to  FIG. 3 , one embodiment of inflatable mattress system  100  having multiple cells, or inflatable chambers, of differing sizes arranged in an advantageous manner to minimize the occurrence of bedsores in a patient is illustrated. In the illustrated embodiment, a group of elongated inflatable chambers  120 ,  121 ,  122  are positioned where an individual&#39;s head would typically rest on the mattress surface. The elongated inflatable chambers  120 ,  121 ,  122  are sized to provide maximum comfort to an individual&#39;s head and neck area. A group of large inflatable chambers  110 ,  111 ,  112 ,  113 ,  137 ,  138  are located where an individual&#39;s shoulders and legs would typically be located on the mattress. The large inflatable chambers  110 ,  111 ,  112 ,  113 ,  137 ,  138  are sized to provide a comfortable cushioned surface for large areas of the human body not susceptible to the formation of bedsores. 
   In a preferred construction, a group of small inflatable chambers  115 ,  116 ,  117 ,  134 ,  135 ,  136  are positioned where an individual&#39;s ankles and a group of small inflatable  125 ,  126 ,  127 ,  128 ,  129 ,  130 ,  131 ,  132 ,  133  are positioned where an individual&#39;s hips would typically be located on the surface of a mattress. Selective inflation and deflation of the illustrated small inflatable chambers provides a variation of the pressure at points of contact between the mattress surface and the body at the most common places for the development of bedsores on a bed-ridden individual. Since the inflatable chambers are small, alternating the amount of pressure from even 1.0 to 1.1 psi can significantly vary the pressure points so as to change the points of contact between the mattress surface and the hips and ankles of an individual. A group of medium inflatable chambers  104 ,  105 ,  106 ,  107 ,  108 ,  109  are located adjacent the group of small inflatable chambers. The medium inflatable chambers provide a measure of support for a grouping of small inflatable chambers. 
   In a preferred embodiment, the inflatable chambers are sized and placed according to the average weight and size of a typical human body. In other embodiments, inflatable chambers may be larger sized to accommodate the weight of a very large person or smaller sized to accommodate the weight of a baby or child. Preferably, elongated inflatable chambers  120 ,  121 ,  122  are sized in a range of approximately 36.0 inches by 3.7 inches to 37 inches by 4.7 inches, and are preferably 36.5 inches by 4.2 inches. Large inflatable chambers  110 ,  111 ,  112 ,  113  are sized in a range of approximately 13.0 inches by 11.3 inches to 14.0 inches by 12.3 inches, and are preferably 12.5 inches by 10.8 inches. Small inflatable chambers  115 ,  116 ,  117  are sized in a range of approximately 8.3 inches by 6.4 inches to 9.3 inches by 7.4 inches, and are preferably 8.8 inches by 6.9 inches. Medium inflatable chambers  104 ,  105 ,  106 ,  107 ,  108 ,  109  are sized in a range of approximately 13.0 inches by 6.4 inches to 14.0 inches by 7.4 inches, and are preferably 12.5 inches by 6.9 inches. Preferably, elongated inflatable chambers, large inflatable chambers, small inflatable chambers and medium inflatable chambers are approximately 3.0 inches thick. 
   The inflatable chambers illustrated in  FIG. 3  are not fluidly connected, so each inflatable chamber may be individually inflated and deflated. Such an arrangement also allows for easy removal and replacement of any worn or damaged cells. 
     FIGS. 4 ,  5  and  6  illustrate, respectively, a side view, a bottom view and a top view of inflatable chamber  140 . Inflatable chamber  140  has a top surface  151  and a bottom surface  152 . In the illustrated embodiment, inflatable chamber  140  is shown as substantially rectangular. However, inflatable chambers of varying shapes such as circular, spherical, cylindrical, toroidal, ovular, triangular could be used as well. 
   Inflatable chamber  140  is constructed of any substantially non-porous, flexible material. For example, inflatable chamber  140  may be manufactured of a vinyl material, the thickness of the material falling within a range from about 0.015 inches to about 0.04 inches, and preferably, is 0.02 inches. Any similar material may be used. A suitable material should be weldable and sealable to create an interior volume in the interior of the inflatable chamber  140 , such that a fluid may be introduced to inflate the cell but the fluid does not escape. In one preferred embodiment, one surface of the inflatable chamber  140  is constructed of the non-porous, flexible material. However, one or more of the surfaces of the inflatable chamber  140  may be manufactured of the flexible material and the remaining surfaces may be manufactured of a different material. 
   The top surface  151  is relatively smooth and adapted to support at least a portion of the weight of an individual positioned on the surface of the inflatable mattress system  100  of  FIG. 3 . The bottom surface  152  has a chamber connector  155  that either introduces fluid into or releases fluid from the inflatable chamber  140 . Chamber connector  155  may be positioned on any surface of inflatable chamber  140  and is configured to connect to a conduit means for communicating fluid to and from the interior volume. In the illustrated embodiment, chamber connector  155  is an aperture in inflatable chamber  140  and a fitting. However, chamber connector  155  may be any element suitable for fluidly communicating between the interior volume of inflatable chamber  140  and any element that supplies, releases or measures fluid such as, for example, a valve, a connector, a PVC or metal conduit, a female or male adapter or a liquid tight flexible conduit and fitting. 
   A deflectable resistor  150  is secured to a surface of inflatable chamber  140  to detect the presence or absence of a pressure point, such as a patient&#39;s weight, on a particular inflatable chamber. In a preferred embodiment, deflectable resistor  150  is secured to the top surface  151 . Deflectable resistor  150  consists of a coated substrate that changes in electrical conductivity as it is bent. The change from a first configuration to a second configuration results in a change in the inflatable chamber  140  from a first inflated position to a second inflated position, which varies the resistance of the deflectable resistor  150  in a predictable way. At any time, the resistance may be measured by applying an electrical signal such as a voltage or a current to the deflectable resistor  150 . Connections may be made to deflectable resistor  150  to capture the deflection information so as to determine the amount of bending or movement that occurs on top surface  151  between a first inflated position and a second inflated position, referred to herein as a deflection signal that is reflective of the movement. 
   A suitable deflectable resistor for purposes of detecting a pressure point on the surface of inflatable chamber  140  is a Bend Sensor® potentiometer manufactured by Flex Point Sensor System, Inc., also described in U.S. Pat. Nos. 5,157,372 and 5,583,476, the disclosure of which is hereby incorporated by reference for all purposes. Deflectable resistor  150  is affixed to the surface of inflatable chamber  140  by any suitable means, and preferably is affixed by a pressure sensitive adhesive that adheres to top surface  151  without affecting the integrity of the material used to manufacture deflectable resistor  150 . 
   Referring now to  FIG. 7 , a block diagram illustrating the electrical and mechanical elements for controlling the operation of the inflatable mattress system of the present invention is shown. In the illustrated embodiment, a controller  200  is communicatively coupled to a processor  205  having computer instructions embodied therein, the combination controlling the overall operation of the inflatable mattress system. Controller  205  is communicatively coupled to a fluid source  210 , a valve assembly  215  and a plurality of deflectable resistors  235 ,  240 ,  245 , thereby allowing for the selective introduction, discharge and measurement of a fluid within the inflatable chambers  220 ,  225 ,  230  based upon a deflection signal received from the deflectable resistors. Although three inflatable chambers are illustrated and described with respect to  FIG. 7 , any number of inflatable chambers may be used depending upon the particular needs of the inflatable mattress system, such as the potential weight of a human body that the inflatable mattress system may support. 
   In the particular device illustrated, controller  200  is comprised of valve controller  275 , fluid controller  265  and reading device  270 . In alternate embodiments, controller  200  may be a mechanical or electrical device that incorporates the functions and operations of valve controller  275 , fluid controller  265  and reading device  270  in either a single device or multiple devices. Valve controller  275  controls the operation of valve assembly  215  by sending a series of signals to the valve assembly  215  to perform various mechanical operations, such as selecting a particular inflatable chamber for inflation, deflation or measurement. Fluid controller  265  controls the strength and duration of the flow of fluid from fluid source  210  to any one of inflatable chambers  220 ,  225 ,  230  by providing a signal to fluid source  210  to initiate the introduction of fluid to inflate a selected inflatable chamber. Reading device  270  receives a deflection signal from deflectable resistors  235 ,  240 ,  245  to determine the location and amount of an individual&#39;s weight that is located on inflatable chambers  220 ,  225 ,  230 . 
   In a preferred embodiment, controller  200  is embodied in any suitable programmable integrated circuit such as M30262 manufactured by Renesas. However, any suitable programmable integrated circuit may be used to supply operating commands that control the operation of valve assembly  215  and fluid source  210 , as well as receive deflection measurements from the surface of inflatable chambers  220 ,  225 ,  230  and pressure measurements from within the respective interior volume of inflatable chambers  220 ,  225 ,  230 . For example, controller  200  may be embodied in an ASIC, or similar application specific integrated circuit. 
   Controller  200  is also coupled to valve assembly  215  through a pressure sensor  255  for reading the pressure within inflatable chambers  220 ,  225 ,  230 . Pressure sensor  255  is typically a pressure transducer capable of measuring the amount of pressure within an inflatable chamber when such as request is issued by either controller  200  or processor  205 . However, any suitable pressure measuring device may be used. In operation, controller  200  is instructed to retrieve a pressure reading within a particular inflatable chamber, for example, inflatable chamber  220 . Valve assembly  215 , via information from valve controller  275 , selects inflatable chamber  220  for a reading. Once chamber  220  is chosen, the pressure reading is taken by pressure sensor  255  and relayed to processor  205  via controller  200 . 
   Processor  205  preferably comprises any computer processor capable of executing a series of instructions to access data from controller  200  and issue commands to controller  200 . For example, processor  205  may contain instructions for selecting certain inflatable chambers for inflation or deflation based on deflection information received from deflectable resistors  235 ,  240 ,  245 . Processor  205  may also contain instructions for randomly selecting inflatable chambers  220 ,  225 ,  230  for inflation and deflation in a particular pattern that provides varying pressure points on the skin of an individual&#39;s body, thereby preventing the formation of bedsores. 
   In the illustrated embodiment, fluid source  210  is coupled via a fluid passage or conduit to valve assembly  215  through a three-way valve  250  and a check valve  260 . However, fluid source  210  may be coupled directly to valve assembly  215  using a conduit or fluid source coupled to the valve assembly  215  through any number of intervening devices such as a flow meter. Three-way valve  250  allows fluid source  210  to introduce fluid into inflatable chambers  220 ,  225 ,  230  through valve assembly  215 . In addition, three-way valve  250  is coupled to the atmosphere through a fluid discharge outlet such that fluid may be removed from inflatable chambers  220 ,  225 ,  230  through valve assembly  215 . Check valve  260  preferably has a crack pressure of 0.15 psi, which prevents back flow through the fluid source  210 . Fluid source  210  is preferably a pump that is sized to provide at least ½ pound per square inch of pressure in inflatable chambers  220 ,  225 ,  230 , such as a 110 VAC model # DDL15B-101, 23 L/m linear diaphragm pump manufactured by Gast that outputs approximately 5 pounds per square inch of pressure, however, any suitable fluid source may be used that is sized in accordance with the particular requirements of the inflatable mattress system. 
   Valve assembly  215  is fluidly coupled to inflatable chambers  220 ,  225 ,  230 . In operation and with reference to an operating command received from controller  200 , valve assembly  215  selects a particular inflatable chamber for inflation or deflation. In inflation mode, valve assembly  215  is operational to introduce fluid from fluid source  210  into a selected inflatable chamber. In deflation mode, valve assembly  215  releases fluid into the atmosphere from a selected inflatable chamber using three-way valve  250  as a fluid discharge outlet. Valve assembly  215  may be any suitable element for selectively supplying fluid from a fluid source  210  or communicating fluid away from a mattress system. One particular embodiment of a valve assembly  215  is described in greater detail with reference to  FIGS. 8–15 . 
   Referring now to  FIG. 8 , valve assembly  301  generally includes a first valve plate  300 , a second valve plate  305 , a valve housing  310  and a drive mechanism  302 . Valve housing  310  is secured to second valve plate  305  using a plurality of securing apparatus  320 . A fluid chamber  311  is formed interior to the valve assembly  301 , resulting from a surface of second valve plate  305  and an interior surface of valve housing  310 . 
   Valve housing  310  has two housing apertures. A first housing aperture  375  is connected to a conduit, or passage,  312 , which is fluidly connected to three-way valve  250  illustrated in  FIG. 7 . Depending upon the setting of three-way valve  250 , fluid may be introduced into or removed from fluid chamber  311  through conduit  312 . Valve housing  310  also has a second housing aperture  380  coupled to an optical sensor  313  that aligns first valve plate  300  with second valve plate  305  of valve assembly  301 . 
   First valve plate  300  is located within fluid chamber  311 . First valve plate  300  is coupled to a drive mechanism  302  that imparts rotational movement to first valve plate  300  relative to second valve plate  305 . Second valve plate  305  has a plurality of outlet apertures  365  that are fluidly connected to each inflatable chamber. Each outlet aperture  365  is coupled to a conduit, or passage,  322  using a conduit coupler  321 . Preferably, conduit coupler  321  is a ¼ inch barbed fitting, however, any suitable coupling means may be used that forms an air tight seal between conduit  322  and the outlet aperture  365  of second valve plate  305 . 
     FIG. 9  illustrates an exploded view of valve assembly  301 . As shown, valve assembly  301  also includes a plurality of O-rings  325 ,  330 , a seal  315  and a plurality of securing apparatus  320  for connecting second valve plate  305  to valve housing  310 . Valve housing  310  is configured to receive pinhole disk coupling  335  and pinhole hub coupling  340  and drive mechanism  302  for imparting rotational movement to first valve plate  300  relative to second valve plate  305  in response to information from controller  200  illustrated and described with respect to  FIG. 5 . Pinhole hub coupling  340  couples the shaft of the drive mechanism  302  to first valve plate  300 . The shaft of drive mechanism  302  passes through pinhole disk coupling  335  such that coupling  335  keeps the shaft of drive mechanism  302  true so as to keep first valve plate  300  from pinching and binding. Preferably, the drive mechanism  302  is a stepper motor manufactured by Oriental Motor, however, any suitable stepper motor may be used in accordance with the requirements of inflatable mattress system of the present invention. 
     FIGS. 10 and 11  illustrate, respectively, a top view and a side view of first valve plate  300 . First valve plate  300  has a first aperture  350  and a second aperture  355  disposed on and protruding through the surface of the valve plate  300 . First aperture  350  and second aperture  355  assist in imparting fluid from fluid source  210  into inflatable chambers  220 ,  225 ,  230  of  FIG. 7 . First aperture  350  may also be used to align valve assembly  301  prior to operation. First valve plate  300  has an integral coupling means  360  for connecting the valve plate  300  to a drive mechanism  302  using pinhole hub coupling  340 , illustrated in  FIG. 9 . 
   Referring now to  FIGS. 12 and 13 , a top view and a side view of second valve plate  305  are illustrated. Second valve plate  305  has a plurality of outlet apertures  365  disposed about and protruding through the surface of the plate. In the illustrated embodiment, there are thirty-two (32) outlet apertures  365  disposed on second valve plate  305 . Two outlet apertures are unused. Fifteen outlet apertures  365  are arranged substantially equal spaced about the second valve plate  305  about a first radius from the center point of the plate and fifteen outlet apertures  365  are arranged substantially equal spaced about the second valve plate  305  about a second radius from the center point of the second valve plate  305 . Outlet apertures  365  are coupled to a plurality of conduits  322  of  FIG. 8 , and each conduit  322  is coupled to a chamber connector  155  of an inflatable chamber  140 , seen in  FIGS. 4–5 , so that an outlet aperture  365  is coupled to each inflatable chamber  140  within the inflatable mattress system. 
   In operation, first valve plate  300  rotates relative to second valve plate  305  using a drive mechanism  302 . Typically, first valve plate  300  is disk shaped and second valve plate  305  is shaped to substantially match the shape of first valve plate  300 . Either first aperture  350  or second aperture  355  on first valve plate  300  aligns with an outlet aperture  365  on second valve plate  305 . Each outlet aperture  365  is fluidly connected to a corresponding inflatable chamber  220 , for example, in the inflatable mattress system. In this way, a fluid path is selectively established to either impart fluid from a fluid source  210  into a selected inflatable chamber  220  or release fluid from a selected inflatable chamber into the environment. 
   Drive mechanism  302 , typically a stepper motor, imparts rotational movement to first valve plate  300 , thereby rotating first valve plate  300  relative to second valve plate  305 . Unlike standard motors, a stepper motor moves in discrete increments to position first plate  300  relative to second plate  305 . Such controlled movement positions either first aperture  350  or second aperture  355  of first valve plate  300  over the selected outlet aperture  365  of second valve plate  305  so as to allow a single inflatable chamber to be inflated or deflated without affecting the integrity of any other inflatable chamber. 
   In the illustrated embodiment, second drive plate  305  has thirty-two (32) outlet apertures  365 . Two of the apertures are not used for either an inflate operation or deflate operation, but instead are used for an alignment operation. The remaining thirty (30) apertures  365  are each coupled to a particular inflatable chamber and, therefore, are used in either an inflate operation or deflate operation. Controller  200  is pre-programmed to recognize which outlet aperture  365  is coupled to which inflatable chamber  220 ,  225 ,  230 , for example, in the inflatable mattress system. Controller  200  may therefore receive information from processor  205  and select a particular outlet aperture  365  coupled to a particular inflatable chamber  220 , for example, and thereafter perform an inflate operation or deflate operation or measure the pressure within the interior volume of the selected inflatable chamber  220 . 
   Drive mechanism  302  is adapted to step first valve plate  300  through all thirty-two (32) outlet apertures  365 , thereby aligning either first aperture  350  or second aperture  355  with a selected outlet aperture  365  in response to a signal from controller  200 . Drive mechanism  302  receives a signal from controller  200  and steps first valve plate  300  to the appropriate outlet aperture  365  on second valve plate  305  corresponding to the selected inflatable chamber  220 . 
     FIGS. 14 and 15  illustrate, respectively, a top view and a side view of valve housing  310 . Valve housing  310  has a first housing aperture  375  for coupling a conduit  312 , seen in  FIG. 8 , leading from a fluid source  210  and the atmosphere, to valve assembly  301 . Valve housing  310  has a second housing aperture  380  for coupling optical sensor  313 . First housing aperture  375  is coupled to fluid source  210  and to the atmosphere through three-way valve  250 . In this way, fluid maybe introduced from fluid source  210  through both three-way valve  250 , conduit  312 , and first housing aperture  375  into the fluid chamber  311  of valve assembly  301 , ultimately finding its way into any one of inflatable chambers  220 ,  225 ,  230 . Similarly, fluid may be released from fluid chamber  311  of valve assembly  301  into the atmosphere through three-way valve  250 . 
   With reference to certain reference numerals in  FIGS. 7–15 , the operation and interconnectivity of valve assembly  215 , controller  200 , inflatable chamber  230 , deflectable resistors  235 ,  240 ,  245  and fluid source  210 , as an example, will be described in detail illustrating an inflatable chamber selection operation, an inflatable chamber inflation operation, an inflatable chamber deflation operation, an inflatable chambers pressure measurement operation and an inflatable chamber deflection reading operation. 
   Assembly valve  215  is operational to select an inflatable chamber  220 , for example, and then either introduce fluid into the selected inflatable chamber  230  or release fluid from the selected inflatable chamber  230 . In this manner, a single inflatable chamber  230  can be inflated and/or deflated in response to information provided from a controller  200  coupled to a processor  205 . In addition, once a particular inflatable chamber  230  is selected, the pressure in the inflatable chamber may be read and recorded by a pressure sensor  255  coupled to the controller  200 . In addition, assembly valve  215  provides an alignment feature that squares-up the drive mechanism  302  of the valve assembly  301  before the valve assembly  301  is operational so that the drive mechanism  302  does not pinch and bind. 
   For an inflatable chamber selection operation, controller  200  establishes that a particular inflatable chamber is to be selected. Processor  205  may instruct controller  200  to select a particular chamber, or cell, or controller  200  may select a particular cell on its own. Controller  200  issues an operating command or signal to valve assembly  215  to a select a particular inflatable chamber, for example inflatable chamber  230 . First valve plate  300  rotates relative to second valve plate  305  until aperture  350  or aperture  355  aligns with the outlet aperture  365  corresponding to inflatable chamber  230 . Typically, an inflate operation, deflate operation and/or measurement operation follows a selection operation. 
   For an inflatable chamber inflation operation, controller  200  establishes that selected inflatable chamber  230  is to be filled with fluid. Processor  205  may instruct controller  200  to inflate the selected cell or the instruction may come from controller  200 . In the embodiment illustrated in  FIG. 7 , fluid controller  265  of controller  200  sends an operating command or signal to fluid source  210  instructing the source to supply fluid into inflatable chamber  230  at a particular strength for a particular duration. Controller  200  also sends an operating command to three-way valve  250  that an inflate operation is about to occur. In response to the signals, three-way valve  250  is placed into the inflate position and fluid flows from fluid source  210  through check valve  260 , three way valve  250  and into valve assembly  302 . 
   Valve assembly  301  had previously selected inflatable chamber  230 , which is now selected for an inflation operation. Fluid travels from fluid source  210  through conduit  312  into first housing aperture  375  and fluid chamber  311 . The fluid then flows through either aperture  350  or aperture  355  into outlet aperture  365 , conduit coupler  321 , and conduit, or passage,  322  corresponding to inflatable chamber  230 . Outlet aperture  365  is coupled to a conduit  322  that is connected to the chamber connector, or fitting,  155  of  FIGS. 4–5  in inflatable chamber  230 . Outlet aperture  365 , the conduit  322  and the fitting  155  and aperture on inflatable chamber  230  form a fluid communication path between valve assembly  301  and the inflatable chamber of  230 . 
   For an inflatable chamber deflation operation, controller  200  establishes that fluid is to be removed from selected inflatable chamber, or cell,  230 . As stated previously for an inflate operation, processor  205  may instruct controller  200  to deflate the selected cell or the instruction may come from controller  200 . Controller  200  sends an operating command or signal to three-way valve  250  that a deflate operation is about to occur. In response to the operating command from controller  200 , three-way valve  250  is placed into the deflate position, thereby creating a fluid path from valve assembly  215  to the environment to release the fluid. 
   Valve assembly  215  had previously selected inflatable chamber  230 , which is now selected for a deflation operation. Fluid travels from the inflatable chamber  230  through the chamber connector aperture and fitting  155  in the inflatable chamber  230  into the conduit  322  coupled to the fitting  155 . The fluid then flows into conduit coupler  321  and outlet aperture  365  of second valve plate  305  that corresponds to inflatable chamber  230 , through either first aperture  350  or second aperture  355  of first valve plate  300  and into fluid chamber  311 . The fluid then passes out first housing aperture  375  disposed in valve housing  310  into conduit  312  and three-way valve  250 . The fluid is then released into the environment. 
   For an inflatable chamber measurement operation, controller  200  establishes that the internal pressure of selected inflatable chamber, or cell,  230  is to be measured. Processor  205  may instruct controller  200  to take a pressure measurement from a particular cell or controller  200  may select a particular cell on its own. Controller  200  sends an operating command or signal to pressure sensor  255  that a measurement operation is about to occur. In response to the command from controller  200 , pressure sensor  255  measures the internal pressure within the previously selected inflatable chamber  230 . 
   Referring again to  FIG. 8 , valve housing  310  having an optical sensor  313  mounted thereon for use in an alignment operation is shown. In general, optical sensor  313  is used to detect the presence of a reflector on an unused outlet aperture  365  on second valve plate  305  to center valve assembly  301  in a home state, i.e. a state in which a wall member of the inflatable chamber is in a position without deflection. Optical sensor  313  consists of two parts, an emitter and a detector. The emitter produces a beam of visible or infrared light which is captured by the detector to produce a signal. Optical sensor  313  is preferably a retroreflective sensor, wherein the emitter and detector are adjacent to each other in the same housing. However, any suitable optical sensor may be used. 
   In an alignment operation, drive mechanism  302  rotates first valve plate  300  until the beam of visible or infrared light from optical sensor  313  passes through aperture  350 . Since second housing aperture  380  of valve housing  310  is aligned with the reflector located on the unused aperture  365  of the second valve plate  305 , the beam of visible or infrared light passes from the emitter of optical sensor  313  through aperture  350  and reflects back to the detector of the optical senor  313 , thereby producing a signal. As such, valve assembly  301  is in alignment and the alignment signal is transmitted from the optical sensor  313  to controller  200 . 
   Controller  200  also receives measurement information regarding the deflection of deflectable resistors  235 ,  240 ,  245  located on inflatable chambers, or cells,  220 ,  225 ,  230  respectively. Reading device  270  located within controller  205  is coupled to deflectable resistors  235 ,  240 ,  245 . At prescribed periods of time, reading device  270  receives deflection signals from deflectable resistors  235 ,  240 ,  245 . For example, if an individual&#39;s body is resting on inflatable chambers  220 ,  225 ,  230 , the deflectable resistors sense a certain amount of deflection on each cell. In response, a deflection signal is transmitted from deflectable resistors  235 ,  240 ,  245  to the reading device  270  in controller  270 . Reading device  270  then forwards the deflection signals to processor  205 . 
   Processor  205  may use the deflection information from deflectable resistors  235 ,  240 ,  245  in a variety of ways. For example, the deflection information provides processor  205  with information regarding the position of a human body on inflatable chambers  220 ,  225 ,  230 . Processor  205  may then instruct controller  205  to alter the pressure within the interior volumes of inflatable chambers  220 ,  225 ,  230  at prescribed intervals to vary the pressure exerted from the surface of the inflatable chambers on the skin of the individual, thereby reducing the formation of bedsores. 
   The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.