US3840921A

US3840921A - Water bed and support therefor

Info

Publication number: US3840921A
Application number: US00338749A
Authority: US
Inventors: R Labianco
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-03-07
Filing date: 1973-03-07
Publication date: 1974-10-15
Anticipated expiration: 1991-10-15

Abstract

A water bed includes a water-filled bladder resting upon a support having an upwardly and outwardly inclined peripheral supporting surface to provide support for the lower peripheral portion of the bladder and to allow the upper peripheral portion of the bladder to bulge over the top of the supporting surface so that the bulging portion and the top wall of the bladder provide comfortable fluid support for the user of the bed. Preferably, the inclined peripheral support surface is made of resiliently deformable material to enhance the comfort of the support provided by the bulging portion of the bladder. Other preferred embodiments of the water bed include a flexible sheath encasing the bladder to prevent escape of water in the event of bladder rupture, and flexible baffles in the bladder providing separate water compartments communicating adjacent the ends of the bladder to dampen wave action of the water.

Description

United States Patent 1 Labianco 111 3,840,921 [4 1 Oct. 15,1974

1 1 WATER BED AND SUPPORT THEREFOR [76] inventor: Richard A. Labianco, 1745 N.

Allen, Pasadena, Calif. 91 104 [22] Filed: Mar. 7, 1973 [21] Appl. No.: 338,749

Primary Examiner-Paul R. Gilliam Assistant ExaminerAndrew M. Calvert Attorney, Agent, or FirmChristie, Parker & Hale [57] ABSTRACT A water bed includes a water-filled bladder resting upon a support having an upwardly and outwardly inclined peripheral supporting surface to provide support for the lower peripheral portion of the bladder and to allow the upper peripheral portion of the bladder to bulge over the top of the supporting surface so that the bulging portion and the top wall of the bladder provide comfortable fluid support for the user of the bed. Preferably, the inclined peripheral support surface is made of resiliently deformable material to enhance the comfort of the support provided by the bulging portion of the bladder. Other preferred embodiments of the water bed include a flexible sheath encasing the bladder to prevent escape of water in the event of bladder rupture, and flexible baffles .in the bladder providing separate water compartments communicating adjacent the ends of the bladder to dampen wave action of the water.

11 Claims, 16 Drawing Figures PATENTEU I 55974 3.840.921

SHEET 10F 5 j Pam Aer P2002 Aer PATENTEU 3,840,921

SHEEI 3 N 5 PATENTEDBET 1 51914 3'. 840.92 1

SHEET 5 (If 5 WATER BED AND SUPPORT THEREFOR BACKGROUND OF THE INVENTION This invention relates to water beds, and more particularly to an improved support structure for an improved water-filled bladder which provides fluid support for the user of the bed.

Previous water beds have several disadvantages which have hindered the water beds ability to break into the conventional bed market. A major disadvantage of previous water beds is their use of a solid. peripheral support frame which completely confines the water-filled bladder. The solid support is 'discomforting to one sitting on the bedside, and a nuisance to one who climbs in or out of bed.

It is also difficult to make up bedding on a water bed confined by a solid frame. The sheets, blankets, and bedspread must be tucked between the heavy waterfilled bladder and the rigid frame. Usually they end up loosened or undone, because the top outer edge of the bladder pulls in from the support frame when pressure is put on the bed, thereby releasing the bedclothes from their support around the bed.

Moreover, standard bedding such as fitted sheets cannot be used easily on conventional water beds because of the confinement of the bladder completely within its support frame.

A further disadvantage is that standard bedspreads the size of conventional cover spreads are not used to cover conventional water beds. Such a bedspread will completely cover the bed and frame and will droop three to five inches on the floor all around the bed, because conventional water beds are generally lower than conventional bed-height, conventional water bed height being about 16 to 20 inchesiabove the floor. If a conventional water bed were mounted on a supporting structure for holding the bed at a level commensurate with conventional beds, then a user attempting to sit on the bedside would have most of his weight supported on the rigid frame, which is very uncomfortable.

Another disadvantage of previous water beds has been occasional leakage of the water-filled bladder. When this happens, the bladder usually has to be emptied at least partially, and the leak found and sealed, or the bladder replaced. This is an obvious inconvenience to the bed owner, and it sometimes requires from several hours to several days to replace or repair the bed.

Conventional water beds, particularly the air-form type (to be described in detail below) experience transverse wave action and reverberation and slapping of water waves against the frame when the user enters, leaves, or turns over in bed.

Many prior art water bed frames also are not sufficiently adaptable to be decorative with any room decor.

SUMMARY OF THE INVENTION This invention provides an improved water bed support structure and water-filled bladder combination which eliminates the above as well as other problems and disadvantages associated with prior art water beds.

Briefly, the improved water bed and support combination includes a water-filled bladder having a top surface for comfortably supporting a user of the bed. A support structure for the bladder includes an upwardly and outwardly inclined peripheral support surface engaging a lower peripheral wall section of the bladder. The inclined peripheral support surface is of such height that an upper peripheral portion of the bladder bulges over the inclined support surface so that both the upper peripheral portion and the top wall of the bladder will provide comfortable fluid support for the user of the bed.

The bulging outer periphery of the water-filled bladder allows the bed user to sit comfortably on the bedside and to easily get onto or .out of the bed. Preferably, the bed is raised to a height commensurate with conventional beds, which improves the comfort of the user sitting on the bedside when compared with convenbladder is calculated to permit the use of standard-size fitted sheets and bedclothes with minimum effort, while improving the ability of the bedclothes to stay on the bed during use. A standard cover spread can be used, allowing the bed to blend with any decor.

Because of the inclined support surface, the bladder provides a comfortable sleeping support with about ten to eleven inches of water depth in the central area of the bed. This depth is sufficient to prevent the user from experiencing uncomfortable bottoming out on the bladder support platform. The inclined support surface also displaces many, cubic-feet of water that would ordinarily be needed in the bladder of a conventional rigid frame water bed of equal size while maintaining equivalentsupport and comfort for the user. Consequently,

the reduced volume of water substantially lightens the bed by several hundred pounds when compared with the conventional rigid frame water bed. In a preferred form of the invention, a protective sheath encases the water-filled bladder to prevent escape of water in the eventof bladder rupture. Thus, if a leak occurs in the bladder, it will not be necessary to repair or replace the bladder until a convenient time. Thesheath also adds tothe strength and durability of the bladder by sharing stresses on the seams and by absorbing any abrasions or punctures which might otherwise cause the bladder to leak.

Preferably, the water-filled bladder also includes flexible baffle means connected between its top and bottom walls to form separate interior water compartments communicating adjacent the ends of the baffles.

The baffles substantially prevent cross-travel of water' waves within thebed, which is an occasional disturbance to the user of conventional water beds.

These and other aspects and advantages of the present invention will be more fully understood by referring to the following detailed description and the'accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS the prior art water bed of FIG. 2 when a user is supported by the bed;

FIG. 4 is a fragmentary cross-sectional elevation view showing a prior art air form or airframe water bed;

FIG. 5 is a perspective view of the prior art waterbed shown in FIG. 4 illustrating the typical reverberating wave action of the water in the bed during use;

FIG. 6 is a fragmentary elevation view, partly in section, showing the detailed constructionof a water bed according to the present invention;

FIG. 7 is an enlarged fragmentary cross-sectional elevation view of the bed construction shown within the circle 7 of FIG. 6;

FIG. 8 is a fragmentary elevation view, partly in section, showing the effect on the bed when a user sits on the bedside;

FIG. 9 is a schematic elevation view illustrating the hydrostatic pressure and tension existing when the bed is not in use;

' FIG. 10 is a schematic elevation view illustrating the hydrostatic pressure and tension existing in the bed when it supports a user;

FIG. 11 is a cross-sectional plan elevation view taken on line 11-11 of FIG. 6;

FIG. 12 is a plan elevation view, partly broken away, showing means for heating the water in the bladder of the bed;

FIG. 13 is a plan elevation view, partly broken away, illustrating the use of a second bladder for sheathing the water-filled bladder of the bed;

FIG. 14 is a perspective view showing the bed ina disassembled condition ready for packaging and ship- P 'FIG. 15 is a'perspective view, partly broken away, showing the construction of the water bed when the bed is used as a couch; and

FIG. 16 is a perspective view, partly broken away, showing the construction of the water bed which provides the appearance of a conventional bed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 1. Prior Art Up until the present time, the conventional way to support a water bed bladder has been through the use of a surrounding framework which completely confines the outer edge of the water-filled bladder. The reason for this is understood best by referring to FIG. 1 which shows an unsupported frameless-water-filled bladder 20 at various levels of water capacity. Each increase in water depth from the levels represented by

bladders

20a, 20b, 20c, and 20d creates more hydrostatic pressure and tension on the side walls of the bladder and on the bottom and top surfaces of the bladder. For example, bladder 201; represents a water depth of approximately 4 inches, at which point the bladder will just start to support the body of the user. Bladder 20c represents a depth of about 6 inches, which will comfortably support the body, with a portion of the .body touching the floor 22. Bladder 20d has a water depth of about 8 inches, which will firmly support a body without any part of it hitting bottom. However, bladder 20d is not the ideal firmness for sleeping,'because bladder top surface 24 is relatively taut. It will create conventional bed pressure points, and will not conform and adjust properly to the different weight proportions of the upper and lower torso of the user.

Both the comfort of the bed and the comfortable sleeping volume of the bladder can be increased by placing water-filled bladder 20 in a surrounding framework, such as a rigid framework 26 shown in FIG. 2. Framework 26 has an upwardly opening recessed area 28 in which the water-filled bladder 20 is disposed. Framework 26 is supported by a generally rectangular block 30 resting on the floor. Block 30 generally supports the top surface of the bladder about 16 to 20 inches above the level of the floor 32. Recessed area 28 of framework 26 generally is of less volume than that of the water-filled bladder, which will allow the horizontal force of the water to be directed against the side walls of the bladder to the framework, as represented by arrows 34. This produces a relativelysmall amount of tension (represented by arrows 36 in FIG. 2) on bladder top surface 24, which allows a comfortable sleeping capacity to be achieved when a water depth of about 9 to 11' inches is present in the bladder.

. FIG. 3 illustrates how the tension on the wall of the bladder of a conventional water bed bladder 20 increases and causes the bladder to pull in from the side framework 26 when a body 38 exerts pressure on bladder top surface 24 at a point close to the peripheral wall 40 of the bladder. This reaction of the bladder 'is responsible for the tendency of the bedclothes to loosen from around the water bed during use. Rigid framework 26 also has several other disadvantages to be described in greater detail below.

Because of the disadvantages of the rigid confining framework of conventional water beds, the air frame or air form water bed'42 shown in FIGS. 4 and 5 was developed. This bed includes anair tube 44 integral with and surrounding a water-filled bladder 46. Air tube 44 becomes substantially stiff when filled with air, and it resists bending to some degree. However, the chief disadvantage of water bed 42 is that air tube 44 acts as a springboard to wave action when pressure is applied to the bladder, such as at a point 48. The resulting reverberating wave action of the water within the bladder is almost jello-like, and can be an occasional disturbance to the user. The bed is also prone to bottoming out during use, because of the lower amount of water capacity predicated by the diameter of the air tubes This volume of water causes the bed to react almost the same way as the bladder shownin FIG. 1, in that the bed is firm in nature because it has no expansion-restricting rigid framework. Further, there is a loss of water bed sleeping area,'because of the encroachment on all sides by the air tubes.

2. Present Invention FIGS. 6 and 7 show a water bed 50 according to this invention, in which the depth of the water used in the bed provides comfort during sleeping and sitting, along with no pressure points or uncomfortable bottoming out on the bottom of the bladder.

Water bed 50 includes a water-filled bladder 52 which may be of any scalable and flexible water-tight material, such as vinyl or rubber. The water-filled bladder is supported above the floor 53by a-support structure 54 which includes a horizontally disposed rectangular, rigid platform 56 for-supporting a major portion of the bottom of bladder 52. Support structure 54 also includes a peripheral substructure resting on the top surface of and extending around the perimeter of platform 56 to provide support for the lower peripheral wall portion of the bladder. The substructure comprises elongated wedge-shaped support members 58 resting on platform 56 and extending along each edge of the rectangular platform. Each support member 58 includes an upwardly and outwardly inclined support surface 60 engaging the bottom peripheral wall portion of the bladder, and a horizontally disposed top surface 61 also supporting a bottom peripheral portion of the bladder. Preferably, inclined support surface 60 extends upwardly and outwardly from the plane of horizontal platform 56 at an angle of less than 45, the preferred angle being about 20.

In its unfilled condition, the bladder lies upon and extends over the outermost extent of the substructure by several inches. When the bladder is filled with water, it draws up and in to provide a comfortable sleeping volume of approximately ID to ll inches in depth in the large central portion of the bladder. The optimum height of support members 58 preferably is 6 inches, so the peripheral top surface of the bladder is approximately 4 to 5 inches above top wall 61 of the support members when the bladder is filled. This configuration of the inclined support surfaces 60 enables the upper peripheral portion 62 of bladder 52 to bulge above substantially the entire width and length of top surfaces 61 of support members 58 when the bladder is filled to a comfort-producing supporting capacity, so that the outermost extent of the water-filled bladder, continuously around its outer perimeter, provides sufficient tension upon and against the upper wall portion of the bladder to provide comfortable fluid support for a person sleeping or sitting on the bedside.

Support structure 54 also supports the bladder in such a manner that a water depth of approximately 10 to l 1 inches is present in the major central area of the bed to provide comfortable sleeping conditions without the user bottoming out on the bottom surface of the bladder or the support structure.

The bladder supports a body resting on its top surface In this condition, the bladder provides a soft supporting surface.

FIG. 10 schematically illustrates the hydrostatic forces at work in the bladder when the bed is in use. A body 71 resting on the top surface of the bladder causes the peripheral edges of the bladder to pull in slightly from its normal position, which produces a slight increase in the horizontal forces F,,, F and F present around the edge of the bed. The body resting on the top of bladder'52 also increases the magnitude of vertical force F,,, which supports the body of the user. The vertical forces F A on opposite sides of the user are of less magnitude than force F,,, so the top surface of the bladder remains in a relatively soft condition comfortably supporting the user with substantially no pressure points.

Bladder 52 and support structure 54 are supported above the floor by a plurality of longitudinally spaced apart, elongated support blocks (only one of which is shown at 64 in FIGS. 6 and 7). Preferably, support blocks 64 are made of a rigid, relatively lightweight maby creating a sufficient amount of hydrostatic pressure p of water upwardly on the top wall of the bladder to cause acceptance of the curves and different weight proportions of the upper and lower torsos of the user. Tension from horizontal forces also is used to prevent the body from sinking too low into the bed. The result is a healthy level support of the back, and beneficial lifting and adjustment of the pelvis and legs to about the level of the chest of the bed user. The back is always fully supported, and the muscles are fully relaxed and blood circulation is improved because of the leg adjustment. The result is a comfortable and healthy sleeping support with no pressure points,-as in a conventional mattress or a taut water-filled bladder which is unsupported at its sides.

FIG. 9 schematically illustrates the hydrostatic pressure and tension forces at work on the top surface of bladder 52 when the bed is not in use. The horizontal force of the water (represented by force vectors F F and F creates tension at various points along the bulging upper peripheral portion of bladder 52. Lateral forces F acting on inclined support members 58 are substantially lower in magnitude than forces F F and F The hydrostatic forces (represented by force vectors F3) on the top supporting surface of the bladder are of substantially less magnitude than the horizontal forces F F and F around the edge of the bladder.

terial, such as polystyrene foam. These blocks preferably are about 1 foot square in transverse cross-section, which maintains the top surface of the water-filled bladder at a levelabove the floor commensurate with conventional beds.

Inclined support members 58 preferably are made of a high-density polyurethane foam, or other relatively deformable material. The support members preferably are upholstered with a layer 66 of naugahyde vinyl or upholstery cloth. The ends of layer 66 are secured to platform 56 byisuitable fasteners 68, such as staples, nails or glue. Support members 58 also may be constructed from wood, or other rigid construction material, and still provide many of the advantages characteristic of the present invention, although it has been found in practice that a relatively deformable support below the peripheral edge of the bladder provides more comfort for the user entering or leaving the bed or sitting at the bedside. There is also no hazardous rigid edge projecting'where persons can injure themselves.

Platform 56 may be made of any suitable composition such as plywood or particle board. Preferably, platform 56 is formed in sections, preferably in halves, joined along the longitudinal centerline of the bed at 70 (shown in FIG. 6) to form the complete rectangular support surface for the bladder.

FIG. 8 shows water bed 50in use with a bed user 71 sitting on the bulging upper peripheral portion of bladder 52. The weight of the user is entirely supported by the hydrostatic pressure of the water in the peripheral portion of the bladder. It should be noted that a bulge at 72 still exists, although the bulge is reduced in height. Any contact between the user and inclined surface 60 on top surface 61 of support members 58 will be comfortable because the foam wedge will compress slightly under the weight of the user. Thus, there is total comfort when the user sits at the bedside, or when he enters or exits the bed. Moreover, the top surface of the bed is at a level commensurate with that of conventional beds, so that the user sitting at the bedside will have his legs extending in a comfortable position with his feet resting on the floor.

A further advantage of waterbed 50 is that conventional bedding may be used with the bed. As illustrated best in FIG. 7, a conventional fitted sheet 74 may be fitted easily over the bulging edge of the water-filled bladder, and simply tucked, under the bulging portion for retention between top wall 61 and the bladder. The sheet is held in a fixed position against wall 61 by the hydrostatic pressure in the bladder. Blankets (not shown) also can be affixed to the bed in the same man-. ner. A conventional bedspread 76 hangs to the floor 53 to further enhance the appearance of the bed which conforms to the appearance of the conventional box spring and mattress type bed.

As shown best in FIGS. 6, 7, and 11, a pair of longitudinally extending and parallel, upright flexible baffle panels 80 are joined with the interior top and bottom surfaces of bladder 52. Each baffle extends for a major portion of the length of the bladder, and thereby forms separate

parallel chambers

82, 84, 86 within the bladder, the ends of the chambers being in intercommunication adjacent the ends of the bladder. The baffles allow water in the bladder to swirl from one chamber to the next (as illustrated by the arrows in FIG. 11) when a body moves on the top surface of the bladder. The baffles substantially eliminate transverse wave action in the bladder, and provide a substantial dampening effect to longitudinal wave action. The dampening of the wave action reduces reverberation or slapping of the water in the bladder during use of the bed, and provides substantially improved comfort for the user when compared with conventional unbaffled water beds. A

Normal wave action in the bladder is rolling and gentle in effect as waves generated in the bladder meets the inclined peripheral support and are directed up the incline where they meet the resistance of the bulge in the bladder. This reaction reduces and redirects the force generated by the waves. Moreover, the absence of a substantially vertical confining framework prevents slapping action of the waves. Since no air tubes are present, there is no jello-like reverberation of the water.

As shown best in FIG. 12, the water bed includes an optional heating device 88 for maintaining the temperature of the water in the bed preferably at or near body temperature. Preferably, heating device 88 is along and flat rubber-sealed resistance wiring element disposed between the bottom of the bladder and platform 56. As shown best in FIG. 12, the heating element is connected to a thermostatic control unit 90 having a thermal sensor 92. f

FIG. 13 shows a preferred bladder assembly for the bed. A flexible outer bladder 94 made'of a scalable water-tight material, such as vinyl or rubber, encase s water-filled bladder 52 to provide a protective sheath around bladder 52. (Outer bladder 94 is not shown in FIGS. 6, 7,and 11 for clarity.) An elongated slotted opening 96 in the top surface of outer bladder 94 provides an entry opening which allows stuffing of bladder 52 inside outer bladder 94 prior to when bladder 52 is filled. Opening 96 also provides an escape for air trapped between the two bladders so that the two bladders'will be held tightly against each other during use. A second opening 98 in outer bladder 94 allows a valve 100 to protrude for filling or emptying bladder 52.

Slots

96 and 98 can be taped closed to form a completely water-tight outer bladder.

In a preferred embodiment the two bladders are sealed to each other around valve 100, thereby eliminating

slots

96 and 98 and forming a leak-proof mattress. A separate valve (not shown) is then provided to relieve air entrapped between the bladders.

FIG. 14 shows the entire water bed 50 in a disassembled condition ready for packaging and shipping. As illustrated best in FIGS. 6, 13, and 14, lateral. support members 58 are split longitudinally into two opposed U-shaped sections.

FIG. 15 illustrates how a small water bed 50 according to this invention can double as a couch when covered with a spread 104 and provided with a bolster 106.

FIG. 16 shows how water bed 50 provides the appearance of a conventional bed when provided with a bedspread 108, pillows 1'10, and a headboard 112.

Thus, the water bed of this invention provides complete comfort and fluid support for a user reclining on the bed or sitting at the edge of the bed, without requiring his legs to be extended into an uncomfortable position. The bed eliminates slapping and substantially reduces wave action found in conventional water beds, especially when restricted by the baffle panels in the inner bladder. The height of the bed and the size of the bladders are in conformance with standard size beds, so that standard size fitted and flat sheets, blankets and bedspreads may be used, resulting in a bed that is easy to make up and will blend with any room decor. The bladders themselves, when sealed together in manufacturing, provide the strongest water-filled bladder presently known in the water bed art. Displacement of water by the foam wedges results in a substantially lighter bed with less'stress placed upon the building floor structure.

The design and light weight composition of the bed support and block structure make the complete bed easy to ship and assemble since the components of the bed are simply placed in position and held in place by the weight of the water.

I claim:

l. A water bed comprising a flexible water-filled bladder having a top surface for supporting a user of the bed, and a bottom surface having a central portion and a peripheral portion; and

a support structure, on which the bladder removably rests, for supporting the bottom surface of the bladder, the support structure having a generally planar lower support member for supporting the central portion of thebladder bottom surface, and a peripheral support member extending around the outer portion of the lower supportimember for supporting the peripheral portion of the bladder bottom surface,

the peripheral support member having an inclined bladder-supporting top surface which extends upwardly and outwardly at an angle of less than 45 relative to the horizontal to an outer portion of maximum elevation located above the plane of the lower support member and extending essentially continuously around the peripheral portion of the bladder bottom surface,

the bladder being supported by the peripheral support member such that a water-filled peripheral portion of the bladder rests upon the top of said outer portion of maximum elevation to maintain the body-supporting top surface of the bladder in a generally planar position spaced above said portion of maximum elevation to provide fluid support for the user of the bed extending essentially continuously above and around the outermost portion of the bed support structure.

2. Apparatus according to claim 1 in which the peripheral support member is made of a compressible material.

3. Apparatus according to claim 2 in which the lower support member is a rigid panel on which the peripheral support member is mounted.

4. Apparatus according to claim 3 including lower support means for resting on a floor to hold the rigid panel above the floor.

5. Apparatus according to claim 3 in which the top surface of the water-filled bladder, in normal, nonsupporting use, extends in a plane between about 4 to 5 inches above said portion of maximum elevation of the peripheral support member.

6. Apparatus according to claim 3 in which the inclined surface of the peripheral support member extends upwardly at an angle of about from the horizontal continuously from its low point to its point of maximum elevation.

7. Apparatus according to claim 6 in which the inclined supporting surface is essentially linear from its low point to its point of maximum elevation.

8. Apparatus according to claim 1 in which the top surface of the water-filled bladder, in normal, nonsupporting use, extends in a plane between about 4 to 5 inches above said portion of maximum elevation of the peripheral support member.

9. Apparatus according to claim 1 in which the inclined surface of the peripheral support member extends upwardly at an angle of about 20 from the horizontal continuously from its low point to its point of maximum elevation.

10. Apparatus according to claim 1 in which the inclined supporting surface is essentially linear from its low point to its point of maximum elevation.

11. Apparatus according to claim 1 including a flexible sheath removably resting on the bladder support structure and encasing at least a major portion of the water-filled bladder to prevent escape of water in the event of bladder rupture.

{U ITED STATES PATENT OFFICE 569 CERTIFICATE OF CORRECTION Fawn; 3,840,921 b d. October 15, 1974 Inventofls) RlHARD LaB IANCO It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

[76] lnventor'z f'R ichard A. Labianco" should read Richard A. LaBianco Signed and sealed this 31st day off Decemoer 1974.

(SEAL) Attest:

MCCOY M. GIBSON JR. C. MARSHALL DANN Attestiog Officer Commissioner of Patents

Claims

1. A water bed comprising a flexible water-filled bladder having a top surface for supporting a user of the bed, and a bottom surface having a central portion and a peripheral portion; and a support structure, on which the bladder removably rests, for supporting the bottom surface of the bladder, the support structure having a generally planar lower support member for supporting the central portion of the bladder bottom surface, and a peripheral support member extending around the outer portion of the lower support member for supporting the peripheral portion of the bladder bottom surface, the peripheral support member having an inclined bladdersupporting top surface which extends upwardly and outwardly at an angle of less than 45* relative to the horizontal to an outer portion of maximum elevation located above the plane of the lower support member and extending essentially continuously around the peripheral portion of the bladder bottom surface, the bladder being supported by the peripheral support member such that a water-filled peripheral portion of the bladder rests upon the top of saiD outer portion of maximum elevation to maintain the body-supporting top surface of the bladder in a generally planar position spaced above said portion of maximum elevation to provide fluid support for the user of the bed extending essentially continuously above and around the outermost portion of the bed support structure.

6. Apparatus according to claim 3 in which the inclined surface of the peripheral support member extends upwardly at an angle of about 20* from the horizontal continuously from its low point to its point of maximum elevation.

9. Apparatus according to claim 1 in which the inclined surface of the peripheral support member extends upwardly at an angle of about 20* from the horizontal continuously from its low point to its point of maximum elevation.