WO1997005806A1

WO1997005806A1 - Chair bed with deflation control apparatus

Info

Publication number: WO1997005806A1
Application number: PCT/US1996/012215
Authority: WO
Inventors: Matthew W. Weismiller; Kenneth L. Kramer; John D. Miller; Philip D. Palermo; David A. Albersmeyer; Eric R. Meyer; Stephen R. Shulte; Gregory W. Branson; Joseph A. Kummer
Original assignee: Hill-Rom, Inc.
Priority date: 1995-08-04
Filing date: 1996-07-25
Publication date: 1997-02-20
Also published as: AU6597196A

Abstract

A support surface apparatus includes a support surface air bladder (1506) located on a deck (400) of a bed (50). The support surface air bladder (1506) includes a seat air zone (1646) and a foot air zone (1502) which are independently inflatable and deflatable. The apparatus also includes a control module (1517) coupled to the seat air zone (1646) and the foot air zone (1502) and to an air handling unit (1046) to control inflation and deflation of both the seat air zone (1646) and the foot air zone (1502) independently. The control module (1517) is coupled to a surface instrument module (1024) of an electrical communication network for partially deflating the seat air zone (1646) automatically and for deflating the foot air zone (1502) automatically upon receiving a signal from the electrical communication network indicating movement of the deck (400) from a bed position to a chair position.

Description

CHAIR BED WITH DEFLATION CONTROL APPARATUS

Background and Summary of the Invention

The present invention relates to a chair bed having an articulating deck movable from a normal bed position to a chair position. More particularly, the present invention relates to a hospital bed including control modules for controlling the articulating deck and support surfaces on the deck to provide an improved chair bed.

The chair bed of the present invention includes an articulating deck having separate, independently movable deck sections. In the illustrated embodiment, a head deck section, a seat deck section, a thigh deck section, and a foot deck section are provided. The bed of the present invention further comprises an electrical communication network having a plurality of modules coupled to the network for performing dedicated functions on the bed. A bed articulation control module is provided for controlling movement of the articulating deck sections relative to each other to move the bed between its generally planar bed position and its chair position.

The bed also includes a support surface located on the articulating deck for supporting a person on the bed. Illustratively, the support surface includes a plurality of air bladders located on the deck. It is understood that any type fluid may be used. The air bladders are preferably divided into separately controlled air zones corresponding to the various deck sections. Therefore, the support surface includes separately inflatable head, seat, thigh, and foot air zones.

The bed of the present invention includes an air handling unit located on a bed frame which is capable of supplying air pressure and/or a vacuum to all the different air bladder zones of the support surfaces. The on-board air handling unit also supplies air pressure and/or a vacuum for use by a plurality of air therapy modules. Typically, the air handling unit is mounted on the base frame of the bed. Preferably, the air handling unit drives two lines simultaneously for supplying both air pressure and vacuum to the air bladder zones and the air therapy modules.

Inflation and deflation of the various surface sections is controlled by a surface instrument control module and an air supply module, both of which are coupled to the electrical communication network on the bed. The surface instrument module and the air supply module both receive signals from the bed articulation control module and from a position sensing module as the bed begins moving from the bed position to the chair position. The surface instrument module and air supply module automatically partially deflate a seat air zone section of the support surface and the foot air zone section of the support surface as the bed moves to the chair position. For this purpose, the seat section includes not only the air zone overlying the seat portion of the deck, but also the air zone overlying the thigh portion of the deck. In the chair position, a person's weight is mostly supported by the thigh sections of the support surface and deck. Such partial deflation of the seat section of the bed is automatically controlled to distribute the person's weight as the bed moves to the chair position. In addition, the bed articulation control module automatically elevates an end or the thigh deck section closest to a foot end of the bed to maintain the patient in a seated position on the chair bed.

The foot deck section is configured to retract as the bed moves to the chair position so that the person's feet can be placed properly on the floor in the chair position. The bed articulation control module sends control signals to an appropriate cylinder or other device to retract the foot deck section automatically as the bed moves to the chair position. The bed articulation control module also provides a signal to an appropriate cylinder or other device to extend the foot deck section when the bed returns to the bed position. An air bellows or other air controlled device can also be used to prove the foot deck section.

The bed surface foot section is also configured to retract or shorten automatically as the bed moves to the chair position to enable a patient's feet to be placed on the floor or on a foot prop. The foot section also collapses or thins to maintain an acceptable chair seat size which also enables the patient's feet to be placed on the floor or foot prop.

In the illustrated embodiment, the surface foot section includes a first set of air bladders configured to collapse in a first direction generally parallel to the foot deck section when the first set of air bladders is deflated, and a second set of air bladders located adjacent the first set of air bladders. The second set of air bladders is configured to collapse in a second direction normal to the foot deck section when the second set of air bladders is deflated so that the surface foot section has a substantially reduced thickness and a substantially reduced length when the first and second bladders are deflated. As discussed above, this deflation occurs automatically based on a signal from the bed articulation control module and the position sense module. The surface foot section is automatically inflated when the bed deck returns to the bed position.

Preferably, the length of the surface foot section is reduced by at least 40% when the first and second air bladders are deflated and the thickness of the surface foot section is reduced by at least 80% when the first and second air bladders are deflated. This feature maintains an appropriate size for a seat section of the chair and permits a patient's feet to touch the floor when the bed is in the chair configuration. Also in the illustrated embodiment, each of the second air bladders is independently controlled as a separate air zone by the foot section control module. The foot section control module selectively inflates and deflates the second air bladders to provide a heel pressure relief in the surface foot section. The first set of air bladders is commonly controlled as a single air zone by the foot section control module.

Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of the preferred embodiment exemplifying the best mode of carrying out the invention as presently perceived.

Brief Description of the Drawings

The detailed description particularly refers to the accompanying figures in which:

Fig. 1 is a perspective view of a chair bed in accordance with the present invention in a bed position showing a side rail exploded away from the chair bed, head side rails and foot side rails positioned along longitudinal sides of a deck, and a swinging foot gate in a closed position;

Fig. 2 is a view similar to Fig. 1 showing the chair bed in the sitting or chair position having a head section of an articulating deck moved upwardly to a back- support position, a thigh section of the deck inclined slightly upwardly, a foot section of the deck moved to a generally vertical downwardly extending down position, a foot portion of the mattress being deflated, and swinging gates moved to an open position with one swinging gate folded next to the chair bed;

Fig. 3 is a diagrammatic view of the chair bed of Fig. 1 showing the chair bed in the bed position including a mattress having an upwardly-facing sleeping surface held a predetermined first distance above the floor, the deck being in an initial bed position supporting the sleeping surface in a generally planar configuration, and the foot section being a first length; Fig. 4 is a diagrammatic view showing the chair bed in a low position;

Fig. 5 is a diagrammatic view showing the chair bed in a Trendelenburg position;

Fig. 6 is a diagrammatic view showing the chair bed in a reverse Trendelenburg position;

Fig. 7 is a diagrammatic view showing the chair bed in an intermediate position having a head end of a head section of the deck pivoted slightly upward from the initial position of the deck, a seat section positioned to lie in the horizontal plane defined by the seat section in the initial position of the deck, and the foot section being inclined slightly so that the foot end of the foot section lies below the position of the foot section when the deck is in the initial position of the deck; Fig. 8 is a diagrammatic view showing the chair bed in the chair position with the head end of the head section pivoted upwardly away from the seat section to a back-support position, the seat section lying generally horizontal as in the initial deck position, the thigh section being raised upwardly, the foot section extending downwardly from the thigh section and being a second shorter length, and the portion of the mattress over the foot section being deflated;

Fig. 9 is a block diagram illustrating a plurality of electronic control modules of the present invention connected in a peer-to-peer network configuration;

Fig. 10 is a block diagram illustrating the support surface system of the present invention including a plurality of a bed articulation control module controlling movement of the articulating deck sections and illustrating a surface instrument module and an air supply module for controlling an air handling unit and a switching valve to selectively supply air pressure and a vacuum to control inflation and deflation of zones of the support surface;

Fig. 11 is an exploded perspective view of the support surface of the present invention illustrating a pulmonary therapy rotational bladder located between the deck of the bed and the surface foundation, an upper air bladder support surface located above the surface foundation, and an inflatable and deflatable surface foot section; and

Fig. 12 is a perspective view illustrating the surface foot section in an inflated configuration when the bed is in a normal bed position and illustrating the surface foot section in a retracted and collapsed configuration when the bed is in a chair position.

Detailed Description of Drawings A chair bed 50 in accordance with the present invention having a head end 52, a foot end 54, and sides 56, 58 is illustrated in Fig. 1. As used in this description, the phrase "head end 52" will be used to denote the end of any referred-to object that is positioned to lie nearest head end 52 of chair bed 50. Likewise, the phrase "foot end 54" will be used to denote the end of any referred-to object that is positioned to lie nearest foot end 54 of chair bed 50.

Chair bed 50 includes a base module 60 having a base frame 62 connected to an intermediate frame module 300 as shown in Fig. 1. Casters 70, 72, 74 and 76 support the base frame 62. An articulating deck/weigh frame module 400 is coupled to intermediate frame module 300. Side rail assemblies 800, 802, 804, 806 and an extended frame module 610 having a swinging foot gate 622 are coupled to articulating deck/weigh frame module 400. A mattress 550 is carried by articulating deck/weigh frame module 400 and provides a sleeping surface or support surface 552 configured to receive a person (not shown) . Chair bed 50 is manipulated by a caregiver or by a person (not shown) on sleeping surface 552 using hydraulic system module 100 so that mattress 550, an intermediate frame 302 of intermediate frame module 300, and an articulating deck 402 of articulating deck/weigh frame module 400 assume a variety of positions, several of which are shown diagrammatically in Figs. 3-8.

Articulating deck 402 includes a head section 404, a seat section 406, a thigh section 408, and a foot section 410. Mattress 550 rests on deck 402 and includes a head portion 558, a seat portion 560, a thigh portion 562, and a foot portion 564, each of which generally corresponds to the like-named portions of deck 402, and each of which is generally associated with the head, seat, thighs, and feet of the person on sleeping surface 552. Chair bed 50 can assume a bed position having deck 402 configured so that sleeping surface 552 is planar and horizontal, defining an initial position of deck 402 as shown in Fig. 1 and as shown diagrammatically in Fig. 3. In the bed position, sleeping surface 552 is a predetermined first distance 566 above the floor. Chair bed 50 can also be manipulated to assume a low position shown diagrammatically in Fig. 4 having deck 402 in the initial position and having sleeping surface 552 a predetermined second distance 568 above the floor, the second distance 568 being smaller than first distance 566. The foot deck section 410 of the articulating deck 402 includes a pivoting portion 466 and a contracting portion 462. Foot deck section 410 has a first length 465 when the deck 402 is in the initial position. Chair bed 50 can be moved to a Trendelenburg position shown diagrammatically in Fig. 5 having deck 402 in a planar configuration and tilted so that head end 52 of sleeping surface 552 is positioned to lie closer to the floor than foot end 54 of sleeping surface 552. Chair bed 50 can also achieve a reverse Trendelenburg position shown diagrammatically in Fig. 6 having deck 402 in a planar configuration and tilted so that foot end 54 of sleeping surface 552 is positioned to lie closer to the floor than head end 52 of sleeping surface 552. As described above, chair bed 50 is convertible to a sitting or chair position shown in Fig. 2 and shown diagrammatically in Fig 8. In the chair position, head end 52 of head section 404 of deck 402 is pivoted upwardly away from intermediate frame 302 to a back-support position providing a pivotable backrest so that head section 404 and intermediate frame 302 form an angle 512 generally between 55 and 90 degrees. Seat section 406 of deck 402 is positioned to lie generally horizontally as in the initial position, foot end 54 of thigh section 408 is slightly upwardly inclined, and foot section 410 of deck 402 extends generally vertically downwardly from thigh section 408 and has a length 464 that is shorter length 465 than when deck 402 is in the initial position. Foot portion 564 of mattress 550 is inflatable and is in a deflated condition when chair bed 50 is in the chair position. Foot portion 564 of mattress 550 is thinner and shorter when deflated than when inflated.

Chair bed 50 is capable of assuming positions in which head, thigh, and foot sections 404, 408, 410 of deck 402 are in positions intermediate to those shown in Figs. 3 and 8. For example, chair bed 50 can assume an intermediate position shown diagrammatically in Fig. 7 having head end 52 of head section 404 of deck 402 pivoted slightly upwardly from the initial position, seat section 406 positioned to lie in the same generally horizontal plane as in the initial position, foot end 54 of thigh section 408 raised slightly upwardly from the initial position, and foot section 410 being inclined so that foot end 54 of foot section 410 lies below head end 52 of foot section 410.

Fig. 9 is a block diagram illustrating the plurality of electronic control modules for controlling operation of the hospital bed. The plurality of modules are coupled to each other using a twisted pair network channel in a peer-to-peer configuration. The peer-to-peer network extends between first and second network terminators 1012 and 1013. Network terminator 1012 is coupled to an air supply module 1014. Air supply module is coupled via the network cable to an accessory port module 1016. Accessory port module 1016 is coupled to the bed articulation control module (BACM) 1018. BACM 1018 is coupled to a communications module 1020. Communications module is coupled to a scale instrument module 1022. Scale instrument module is coupled to a surface instrument control module 1024. Surface instrument control module is coupled to a position sense and junction module 1026. Position sense module 1026 is coupled to the network terminator 1013. A left side standard caregiver interface module 1028 is also coupled to the network by a tee connection in the position sense module 1026. The right side standard caregiver interface module 1030 and a graphic caregiver interface module 1032 are also coupled to the network using the tee connector in the position sense module 1026. It is understood that the modules can be rearranged into a different position with the peer-to-peer communication network. The modules are configured to communicate with each other over the network cable without the requirement of a master controller. Therefore, modules can be added or removed from the network without the requirement of reprogramming or redesigning a master controller. The network automatically recognizes when a new module is added to the network and automatically enables a control interface such as the graphic caregiver interface module 1032 to display specific module controls for the added module. This eliminates the requirement for separate controls on the individual modules.

Power for the communication network is supplied by a power supply and battery charge module 1062. Power supply 1062 is coupled to a power entry module 1063 which is coupled to an AC main plug 1065. Power supply module 1062 converts the AC input from plug 1065 to DC levels to be used by the electronic modules. The power supply module 1062 also provides power for limited bed functionality upon removal of the AC main power plug 1065 through a battery 1067. The power supply module 1062 contains an automatic battery charging circuit with an output to indicate battery status. The power module 1062 also control a hydraulic pump 1055.

The bed articulation control module (BACM) 1018 is the module that controls movement of the bed. BACM 1018 controls actuation of a plurality of solenoids which open and close valves coupled to hydraulic cylinders to move the articulating deck sections of the hospital bed relative to each other. BACM 1018 is also coupled to a Break Not Set sensor and a Bed Not Down sensor. When BACM 1018 receives an input signal from the network requesting movement of the bed to a predetermined position, the BACM 1018 first reads the position of the bed provided from position sense module 1026. If movement of a portion of the bed is necessary, BACM 1018 checks for a lockout signal from the left and right standard caregiver interface modules 1028 and 1030. If the lockouts are not set, BACM 1018 controls activation of the selected solenoid 1054 and then BACM 1018 turns on the hydraulic pump 1055 (gravity may also be used if appropriate) to actuate a selected cylinder if necessary. Details of the mechanical structure of the bed, the electronic control modules, the peer-to-peer communication network, and the modular therapy and support surface of the present invention are described in copending U.S. Patent Application No. 08/511,711 filed 04 August 1995, entitled CHAIR BED, the disclosure of which is hereby expressly incorporated by reference into the present application.

Details of the air support surfaces, the articulating deck, and the control modules of the present invention are illustrated in Fig. 10. The support surface of the present invention is configured to be positioned over a bed deck 402 of a hospital bed. The support surface includes a surface foundation 1500 located on the bed deck 402. An inflatable and deflatable surface foot section 1502 is located adjacent surface foundation 1500. An upper air bladder 1506 is positioned over surface foundation 1500.

As discussed above, the articulating deck includes separate, independently movable deck sections. Specifically, deck 402 includes a head deck section 404, a seat deck section 406, a thigh deck section 408, and a foot deck section 410. Upper air bladder 1506 includes a plurality of separate air bladders. The air bladders are preferably connected in three independently controlled air zones corresponding to the different sections of deck 402. Specifically, air bladder 1506 is divided into a head air zone 1648, a seat air zone 1646, and a air thigh zone 1644. The separate surface foot section 1502 which overlies foot deck section 410 is also independently controlled.

An air surface control module 1517 is provided for selectively coupling the various air zones 1644, 1646, and 1648 to the air handling unit 1046. Air surface control module 1517 includes separate valves and pressure sensors for each air zone 1644, 1646, and 1648 of air bladder 1506. When a command to move the bed deck is transmitted to the network from a user input control on one of the standard caregiver interface modules 1028 and 1030, the graphic caregiver interface module 1032, or from another control device, the BACM 1018 actuates appropriate cylinders to articulate the deck 402. The BACM 1018 also provides signals to surface instrument module 1024 and air supply module 1014 for controlling inflation and deflation of the surface foot section 1502 and the independent air zones 1644, 1646, and 1648 of upper air bladder 1506 automatically as the bed articulates.

The surface instrument module 1024 sends signals to a controller inside the air surface control module 1517 to open and close valves at predetermined intervals to control inflation and deflation of the air zones 1649, 1646, and 1648. The surface instrument module 1024 and the air supply module 1014 also receive signals over the network from the position sense module 1026 to indicate the position of the articulating deck sections 409, 406, 408 and 410.

As discussed above, the surface foot section 1502 is deflated as the deck 402 moves to the chair position. In addition, seat air zone 1646 and thigh air zone 1644 are partially deflated to distribute the weight of the person in the chair. When in the chair position, the surface thigh bladder 1644 and the thigh deck section 408 support most of a patient's weight. This partial deflation of the chair seat section is controlled automatically by surface instrument module 1024, air supply module 1014, and air surface control module 1517 as the bed deck moves from the bed position of Fig. 1 to the chair position of Fig. 2. In some instances, a single air bladder may be provided for seat air zone 1646 and thigh air zone 1644. In other instances, a plurality of individual air zones may be all separately controlled. In other words, each of the air zones of air bladder 1506 may have several independently controlled air bladders 1642 as illustrated in Fig. 11. Separate valves and pressure sensors in air surface control module 1517 are provided for interconnecting the various air zones 1644, 1646, and 1648 to the communication network of the bed and to on-board air handling unit 1046. The present invention also includes a foot section control module 1514 which includes valves and pressure sensors for each air zone of the surface foot section 1502.

Each of the control modules 1514, 1517 is designed to physically and functionally connect the various air zone bladders and to both the communication network of the hospital bed through the surface instrument module 1024 and to the air handling unit 1046 which is controlled by air supply module 1014. Air supply module 1014 is coupled to the peer-to-peer communication network. Air supply electronics 1528 are connected to air supply module 1014 for controlling air handling unit 1046 and switching valve 1530 based on network commands for controlling the various surface and treatment modules illustrated in Fig. 10.

Air handling unit 1046 is configured to supply air under pressure to switching valve 1530 on line 1532. Air handling unit 1046 also applies a vacuum to switching valve 1530 through line 1534. An output of switching valve 1530 is coupled to a connector block 1536. Connector block 1536 provides an air and vacuum supply line 1515 to the foot section control module 1514 and provides an air and vacuum supply line 1519 to the air surface control module 1517. It is understood that dual control lines for both air and vacuum can be supplied to each of the foot section control module 1514 and the air surface control module 1517. This dual control allows each module to apply pressure and vacuum simultaneously to different zones of a bladder or treatment device.

The surface instrument module 1024 which is also coupled to the peer-to-peer communication network is electrically coupled to the foot section control module 1514 by lines 1521 and to the air surface control module 1517 by lines 1523. This network connection permits electric controller or microprocessors in the control modules 1514 and 1517 to receive input commands from other network modules and to output information to the network. The surface foot section 1502 is particularly designed for use with the chair bed of the present invention. The foot section 1502 includes a first set of air bladders 1618 and a second set of air bladders 1620 alternately positioned with air bladders 1618. Air bladders 1618 and 1620 are configured to collapse to a near zero dimension when air is withdrawn from the bladders 1618 and 1620. The first set of bladders 1618 are oriented to collapse in a first direction which is generally parallel to the foot section 410 of the bed deck as illustrated by double headed arrow 1622. The second set of bladders 1620 are configured to collapse in a second direction generally perpendicular to the foot deck section 410 as illustrated by double headed arrow 1624. This orientation of bladders 1618 and 1620 in foot section 1502 causes the foot section 1502 to retract or shorten and to collapses or thin as the bladders 1618 and 1620 are deflated by the foot section control module 1514 as the hospital bed moves from a bed orientation to a chair orientation. In the chair orientation, the foot deck section 410 and surface foot section 1502 move from a generally horizontal position to a generally vertical, downwardly extending position. Preferably, the foot deck section 410 moves from a retracted position to an extended position to shorten the foot deck section as the articulating deck of the bed moves to a chair configuration.

Each of the vertically collapsible bladders 1620 are separately coupled to foot section control module 1514 by separate pressure/vacuum supply lines and sensor lines. Therefore, each of the three bladders 1620 are independently coupled to and controlled by foot section control module 1514. Each of the three horizontally collapsing bladders 1618 are commonly connected to a common pressure/vacuum source of the foot section control module. A single sensor line is used to determine the pressure in the common zone of the interconnected bladders 1618. This control configuration permits independent inflation and deflation of bladders 1620 to provide heel pressure relief in foot section 1502. Details of the heel pressure management apparatus are illustrated in copending U.S.

Patent Application Serial No. 08/367,829 filed January 3, 1995, owned by the assignee of the present application, the disclosure of which is hereby expressly incorporated by reference into the present applications. In Fig. 11, the upper air bladder 1506 is located on foam foundation base 1606 between side bolsters 1608 and 1610. Upper air bladder 1506 includes a plurality of adjacent air tubes or bladders 1642 oriented transverse to a longitudinal axis of the bed. Illustratively, bladders 1642 are connected in three commonly controlled zones 1644, 1646, and 1648 as discussed above. It is understood that more zones may be provided. If desired, each bladder 1642 may be controlled independently.

The surface instrument module 1024 receives commands from the BACM 1018 and the position sense module 1026 to control the air surface control module 1517 to reduce the pressure in a seat section defined by zones 1644 and 1646 of the upper air bladder 1506 automatically as the bed moves to the chair configuration in order to distribute a patient's weight. An end of the thigh deck section 408 closest to foot end 54 is angled upwardly automatically as illustrated in Fig. 8 to help maintain the patient in a proper position on the seat when the bed is in the chair configuration. A pulmonary rotation bladder 1508 is located between foundation base 1606 and step deck 1596. It is understood that rotation bladder 1508 may be positioned between foundation base 1606 and upper air bladder 1506 if desired. Rotation bladder 1508 includes separate bladders 1650 which are oriented to run parallel to a longitudinal axis of the hospital bed. Illustratively, three separate pressure zones 1652, 1654, and 1656 are provided in rotation bladder 1508. In the illustrated embodiment, each of the pressure zones 1652, 1654, and 1656 are independently controlled by pressure supply lines 1658.

Each pressure supply line is coupled to a separate valve in pulmonary control module 1520 illustrated in Fig. 2. A separate sensor line (not shown) for each zone 1652, 1654, and 1656 is also coupled to pulmonary rotation control module 1520.

Although the invention has been described in detail with reference to a certain preferred embodiment, variations and modifications exist within the scope and spirit of the present invention as described and defined in the following claims.

Claims

CLAIMS :

1. A chair bed for supporting a person, the chair bed having a head end, a foot end, and opposing sides, said chair bed comprising a frame, a deck supported on the frame, the deck including separately movable head, seat and foot deck sections, a mattress located on the deck and having an upwardly-facing patient surface and head, seat and foot portions corresponding, respectively, to said head, seat and foot deck sections, said seat and foot portions being independently inflatable and deflatable, said head deck section and said mattress head portion thereon being pivotable from a generally horizontal down position through various positions upwardly to a back- support position, and said foot deck section and said foot mattress portion thereon being pivotable from a generally horizontal up position through various positions downwardly to a generally vertical downwardly extending down position as the deck moves from a bed position to a chair position, and an air surface control module for automatically deflating said mattress seat and foot portions as the deck moves from the bed position to the chair position.

2. The chair bed of claim 1, further comprising a control coupled to the deck which raises a connection of the foot and seat deck sections relative to a connection of the seat and head deck sections when converting from the bed position to the chair position.

3. The chair bed of claim 1, wherein said deck includes a thigh deck section connecting said seat and foot sections, and further comprising a control which raises a connection of the foot and thigh sections relative to a connection of the seat and thigh sections when converting from the bed position to the chair position.

4. The chair bed of claim 1, further comprising a control coupled to the deck which lowers said deck relative to said frame when converting from the bed position to the chair position.

5. A chair bed for supporting a person, the chair bed having a head end, a foot end, and sides, the chair bed comprising: a frame; an articulating deck supported on said frame, said deck comprising longitudinally spaced head, seat, thigh and foot sections with the head, thigh and foot sections being movable relative to the seat section and to each other from a bed position to a chair position; a mattress supported on the deck and having head, seat, thigh and foot mattress portions corresponding, respectively, to the head, seat, thigh and foot sections of said deck; said foot section of said deck being movable from a generally horizontal up position to a generally vertically downwardly extending down position to permit the lower legs and feet of the person to be lowered, an end of said thigh deck section closest to the foot end of the bed being pivotably movable upwardly when said foot section moves downwardly to convert the bed to a chair, said mattress foot portion being inflatable to serve as a patient surface when inflated and when said foot section of said deck is generally horizonal, controls coupled to the seat mattress portion and the thigh mattress portion for partially deflating the seat mattress portion and the thigh mattress portion automatically and for deflating the foot mattress portion automatically as the articulating deck moves from the bed position to a chair position.

6. The chair bed of claim 5, wherein said deck foot section is a first length when the foot section is in the up position and a second length shorter than said first length when the foot section is in the down position.

7. The chair bed of claim 6, wherein the deck foot section includes a pivoting member pivoting about a pivot axis between the up position and the down position and a contracting member slidably coupled to the pivoting member for sliding movement between an expanded position when the foot section is in the up position and a contracted position when the foot section is in the down position.

8. A support surface apparatus for use on a bed having a base frame, an articulating deck coupled to the base frame, the articulating deck being movable from a bed position to a chair position, an electrical communication network, an air handling unit mounted on the base frame, and a control interface coupled to the electrical communication network for transmitting command signals to the network, the support surface apparatus comprising: a support surface air bladder located on the deck, the support surface air bladder including a seat air zone and a foot air zone which are independently inflatable and deflatable; and a control module coupled to the seat air zone and the foot air zone and to the air handling unit to control inflation and deflation of both the seat air zone and the foot air zone independently, the control module being coupled to the electrical communication network for partially deflating the seat air zone automatically and for deflating the foot air zone automatically upon receiving a signal from the electrical communication network indicating movement of the deck from the bed position to the chair position.

9. The apparatus of claim 8, wherein the bed includes a position sense module coupled to the network the position sense module transmitting information to the control module related to the position of the articulating dec .

10. The apparatus of claim 8, wherein the deck includes a planar foot deck section, and the foot air zone includes a first set of air bladders configured to collapse in a first direction generally parallel to the foot deck section when the first set of bladders is deflated, and a second set of air bladders configured to collapse in a second direction when the second set of bladders are deflated.

11. The apparatus of claim 10, wherein each of the second air bladders is independently coupled to the air handling unit and controlled as a separate air zone by the control module, the control module selectively inflating and deflating the second air bladders independently to provide a heel pressure relief in the surface foot air zone.