Abstract:
A bed including a flexible air-inflatable bladder embraced by a flexible inextensible shroud. The shrouded bladder may be encircled by a surround to define the outer periphery of the resulting mattress construction. An inextensible layer can be peripherally attached to the upper edge of the surround.

Description:
FIELD OF THE INVENTION  
         [0001]    Providing to an air-inflated bed stability, longevity, and shape retentiveness.  
         BACKGROUND OF THE INVENTION  
         [0002]    Air-inflated beds, commonly called “air beds” include an impermeable bladder which is sufficiently deformable to accommodate to the contours of a person lying on it. The amount of deflection and thus the hardness of the bed, is adjustable by varying the air pressure. Air beds are not to be confused with water beds. Although they both are filled with a fluid, the differences in properties of liquid and gas lead to different problems. This invention is limited to improvements in air beds.  
           [0003]    For reasons of cost and function, it is common to form the air-containing bladder with a skin of an organic plastic sheet material, usually a plasticized vinyl. Such a skin adequately retains air under pressure, and flexes to accommodate the occupant. However, such material also has the property of extensibility it can stretch and balloon.  
           [0004]    This capacity to stretch and balloon often leads to unsightliness of the bed faces, especially the top side, and end faces. Such distortions are unwelcome in fine beds. In conventional double beds which utilize two parallel and edge-contiguous inflated bladders, often one bladder will rise and lap over the other, even when side bolsters are provided. In others, longitudinal ridges will be formed on the bladder, and thus on the top of the bed, and also form a valley between the bladders.  
           [0005]    Because the bladder can extend laterally, it is possible for the outer side face to balloon destroying the symmetry of the bed, This is often countered by a rigid side enclosure, an added element of cost.  
           [0006]    A less visible but often costly situation arises when the plastic material is overlaid by a layer of a substance such as an organic foam. Such layers are often provided to improve the comfort of the mattress. Such layers can leach plasticizer from the vinyl. After enough plasticizer had been leached out, the sheet may crack and leak. Then the leak must be repaired or the entire bladder must be replaced.  
           [0007]    These problems have long been recognized, and attempts have been made to alleviate them. Invariably they have done an inefficient job, and have been too expensive.  
           [0008]    It is an object of this invention to stabilize the basic configuration of the bed, and extend the life of the bladder at an economical cost, and also to dispense with bed components that previously were thought to be necessary.  
         BRIEF DESCRIPTION OF THE INVENTION  
         [0009]    According to this invention, one or two bladders are utilized, depending on whether the bed is to be single or double. Each bladder has a flexible, impermeable skin and means to inflate it with air. The bladder when inflated has a top face, a bottom face, two side faces and two end faces. The bladder is formed from sheet material. Because of internal channeling structures, the top and bottom faces are not purely planar without restraint, the side surfaces will tend to bow out obtusely, and the corners will be rounded, as will the edges of the top and bottom faces. These are well-recognized bladders which when held in a suitable bounding structure and within layers of material laying on the top face, will provide an acceptably flat and rectangular-appearing bed, at least at first.  
           [0010]    According to a feature of this invention, the bladder is enclosed in a shroud of flexible material which itself is substantially inextensible. Its area is formed with dimensions that are substantially equal to the desired ultimate outer dimensions of the bladder when inflated, and before being stretched. Accordingly, when inside the shroud, no dimension of the bladder can “grow” beyond its design shape, no matter what air pressure is exerted in the bladder, and no matter what loads are placed on the beds.  
           [0011]    The shroud is preferably a continuous band wrapped peripherally around the top and the sides of the blender, while at least one of the ends, or preferably both, is or are openable to receive the bladder, and closeable so as fully to encapsulate the bladder. Thus the bladder is trapped against growth beyond its design dimensions.  
           [0012]    According to a preferred but optional feature of the invention, in the double bed configuration the adjacent side faces of both shrouds are fixed to the bottom surface.  
           [0013]    According to yet another preferred but optional feature of the invention, in the double bed configuration, the adjacent edges of the top surfaces of the shrouds are joined, and are also joined to the adjacent lower edges, by a web which forms in common the adjacent side faces of the shrouds.  
           [0014]    According to still another preferred but optional feature of the invention, side and end bolsters adjoin the sides and ends of the shrouds, presenting a concave shape to receive the sides and ends of the shroud to resist outward, tilting, and upward movement of the outer sides and ends.  
           [0015]    According to still another preferred but optional feature of the invention, a flexible surround embraces the assembled group of bladders to hold them in an assembled array. 
       
    
    
       [0016]    The above and other features of this invention will be fully understood from the following detailed description and the accompanying drawings, in which:  
       BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    [0017]FIG. 1 is a perspective view, partly in dashed-line notation showing the relationship of the shroud and the bladders;  
         [0018]    [0018]FIG. 2 is an exploded view of the presently-preferred embodiment of the invention;  
         [0019]    [0019]FIG. 3 is a cross-section taken at line  3 - 3  in FIG. 1;  
         [0020]    [0020]FIG. 4 is a cross-section similar to FIG. 3 showing a modification of the invention;  
         [0021]    [0021]FIG. 5 is a cross-section similar to FIG. 4, showing a defect of the prior art;  
         [0022]    [0022]FIG. 6 shows the presently preferred shroud construction, similar to that shown in FIG. 3;  
         [0023]    [0023]FIG. 7 is a cross-section showing another construction for the shroud; and  
         [0024]    [0024]FIG. 8 is a cross-section showing yet another construction for the shroud. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0025]    [0025]FIG. 1 illustrates the relationship between shroud  10  and bladders  11 ,  12 . The shroud provides a pocket  13 ,  14  for each of the bladders. The structure includes a peripheral tube-like surround  15 , and end closures  16 ,  17 ,  18 ,  19  to close the ends of the surround.  
         [0026]    At least one end closure for each bladder can be opened to receive the bladder. If desired, the other may also be openable, or be permanently closed. With both ends open the bladder can more conveniently be inserted. Attachments means  20  such as hook-loop strips may be provided releasably to hold the closures in the closed position.  
         [0027]    As will be seen, when the end closures are closed and the bladders are inflated, the bladder is entirely encapsulated. While a double bed is illustrated, all of the considerations regarding the double bed are applicable to single bladder (single bed) installations.  
         [0028]    As best shown in FIG. 2, hoses  21  are provided to conduct inflation air into the bladders. They pass through ports  22 ,  23  in end closures  16 ,  17 . The bladder includes an outer impermeable and flexible skin  25 . It is formed from sheet material to the desired shape by tailoring pieces to size and joining them by seam welding techniques. Inner structures are usually provided to restrict flow of air from one region to another inside the bladder. They form no part of the invention, and require no detailed description here.  
         [0029]    The material used is usually a plasticized vinyl material which can be stretched. As described above, such stretching can lead to distension and ultimate damage to the bladder. The bladder is formed so that, when it is inflated and enclosed, it will fill any available room for expansion. The dimensions of the bladder structure are selected so that when it is restricted, its surface will fill the volume defined by the bladder before being substantially stretched.  
         [0030]    The bladder includes dimension  26  of longitudinal length, of width  27  and of depth  28 . When inflated as stated, its surface area will be near to the arithmetic product of these dimensions.  
         [0031]    A shroud  30  according to this invention has dimensions of length, width and depth substantially equal to dimensions  26 ,  27  and  28  of the inflated bladder.  
         [0032]    The material of the shroud is selected to be flexible, but not appreciably stretchable. Tightly woven fabrics are suitable for this purpose. The intended result is for the shroud to define the intended shape of the inflated mattress.  
         [0033]    The upper face  31  of the shroud performs an additional function. A good cotton based fabric will not tend to leach plasticizers from the bladder material. Heretofore it has been expedient to place an independent layer of similar material on the top of the bladder for this purpose. Because the shroud material performs this additional function, the extra layer can be omitted, at a surprisingly large saving of cost.  
         [0034]    As best shown in FIGS. 2 and 3 the bladders (only bladder  11  will be described in detail, because both are alike) has a pair of side faces  33 ,  34  end faces  35 ,  36 , top face  37  and bottom face  38 . These faces are intended to be sensibly planar in the bed as installed, although curvature at the corners and edges is to be expected.  
         [0035]    When installed as a mattress, the assembled shroud and bladder or bladders will be laid into a receptacle formed by side surround  40  (FIG. 2). Surround  40  has a base sheet  41  of cloth laid on the floor. A band  42  is attached at its lower edge  43  to the base sheet. Band  42  is formed as an open rectangular structure, often of soft and decorative material. The resulting rectangular shape is defined by its attachment to the base sheet. As such, it becomes a receptable for the encapsulated bladders.  
         [0036]    In prior art constructions, a layer of sheet material is often stitched to the upper edges of the surround to keep it from spreading. An advantage of this invention is that such reinforcement is not necessary, and an element of cost is saved.  
         [0037]    Instead, a comfort layer  45  of foam material (perhaps egg-crate type material) can simply be laid in the upper surface of the shroud. The shroud protects the bladder from leaching out of its plasticizer. Normal sheets or bed pads (not shown) can be laid directly onto comfort layer  45 .  
         [0038]    The shroud can be provided in several configurations. They all have in common their embrace of all faces of each bladder. The cloth shape can be formed by sewing or cementing as preferred, joining suitably tailored pieces of material.  
         [0039]    [0039]FIG. 4 shows the presently preferred embodiment of shroud  50 , because it is readily manufactured. The peripheral portion  57  extends completely around both of the bladders to embrace their top faces, bottom faces, and outer side faces. A web  52  of similar material is attached to the under (inside) surface of the top of portion  57  and to the upper (inside) surface of the bottom of portion  51 . This web may be attached by stitching or cementing as desired.  
         [0040]    The end closures are stitched to the upper end edges of portion  57 , and are fastened at the lower end edges by a suitably means such as Velcro (TM), a loop and hook fastener.  
         [0041]    The construction of FIGS. 3 and 6 is preferred for its ease of manufacture, and also because of the joinder of the web at attachment seams  55 ,  56 . This provides optimum restraint against sidewise rolling movement of the mattress, and also enlists each bladder in side support of the other.  
         [0042]    [0042]FIG. 7 shows that instead of a web, each bladder  60 ,  61  can have its own respective shroud  62 ,  63 . It is convenient to use base sheet  64  as the lower part of the shroud, although individual, complete separate shrouds may be provided. In any event the lower inner parts of the shrouds, such as parts  65 ,  66  should be anchored to base sheet  64 .  
         [0043]    [0043]FIG. 7 offers the advantage that both shrouds are independent and both use the base sheet as part of the shroud. Attachment points  67 ,  68 ,  69  illustrate this feature. If desired, both shrouds can be part of a single sheet of material.  
         [0044]    [0044]FIG. 8 shows another scheme in which shroud  70  is a complete “arch”. Shroud  71  is a partial arch, and uses leg  72  of shroud  70  as a web in common with shroud  71 .  
         [0045]    It will be appreciated that persons skilled in the art of sewing flexible structures can conceive of other arrangements, all of which will be within this invention.  
         [0046]    Many prior art constructions have by necessity used relatively rigid bolsters along the sides and ends of the mattress to limit the blowing out of the bed. While the improvements of this invention eliminate the need for them, they may be used if desired.  
         [0047]    [0047]FIG. 4 shows a pair of foam bolsters  80 ,  81  which extend along the sides of the bladders. Similar bolsters (not shown) abut the ends. The same surround holds the bolsters against the bladder or bladders. A concave surface  83  is intended to trap the edge of the bolster to keep it from climbing.  
         [0048]    There is a problem in the prior art when a shroud is not used. The tendency is shown in FIG. 5 for the bladders not only to expand laterally, but for one to climb over the other, while bowing out the bolsters. As shown, bladder  86  is climbing on bladder  87 , and bolsters  88  and  89  are forced apart. This is totally unacceptable, so it is known to hold the two bolsters down, an element of significant expense. It is a benefit of this invention that, while bolsters can if desired be used, they need not be interconnected.  
         [0049]    The bed of this invention is finished with a finish layer  90 , usually of attractive quilted material, which is preferably attached around its periphery to the peripheral upper edge of the surround. This attachment can be accomplished by a separable zipper along the respective edges and relates in a singularly stable bed, with or without bolsters.  
         [0050]    The underlying foam layer can, if desired, be provided in two pieces instead of one. The occupants can thereby have different levels of cushioning resistance as well as individually selectable inflation air pressure.  
         [0051]    The problem of “rollover” is well known to users of air beds. Even with internal channeling, there is ordinarily some shear movement between the top and the bottom of the bladder. When the shroud is used, especially in a double bed, and the shroud or shrouds is or are attached to be base sheet as shown, such movement is considerably resisted.  
         [0052]    Ultimate ballooning of the bladders is prevented by the shroud, and then results a long-lived attractive bed well worth a premium price.  
         [0053]    This invention is not to be limited by the embodiments shown in the drawings and described in the description, which are given by way of example and not of limitation, but only in accordance with the scope of the appended claims.