Abstract:
A mattress embodying a foam encasement surrounding individually wrapped coils and lacking a barrier separating upholstery layers from the coil assembly. Border material is affixed to sidewalls forming the foam encasement and the upholstery layer is tacked to a base of the foam encasement.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to mattress construction. More particularly, the present invention relates to a mattress including structure that minimizes a drum effect as well as a construction approach lending itself to the use of superior materials without significantly increasing the cost of making a luxury mattress. 
     In conventional mattresses for use as beds, it has been recognized that certain mattresses include structure creating an undesirable drum effect such that the sleeper does not benefit from mattress substructure but rather, sleeps on a drum-like surface. It has also been recognized that it is important to provide a mattress made from high quality raw materials so that the mattress maintains consistent resiliency across a sleeping surface and the tendency for the creation of permanent depressions is minimized. 
     Due to wear and tear, the surface of a conventional mattress might sag, shift, lose its form, etc. A sleeper lying on the mattress might inadvertently roll off the mattress due to the lack of support at the sagging edge. To overcome such problems, there have been many approaches to mattress design. 
     Most improvements in the area of mattress design focus on the innerspring unit of the mattress. The innerspring unit is usually made from a plurality of spring coils arranged side-by-side in a rectangular matrix. A border made of metal wires encircling both the upper and lower surfaces frame the innerspring. The plurality of helical spring coils are positioned in a spaced apart relationship within the innerspring unit to provide the internal support for the mattress. 
     Some examples of mattresses using a modified innerspring unit include a pair of ridges formed on a sheet of elastomeric material that covers both sides of an innerspring unit. The elastomeric material is attached to the innersprings. Other approaches involve a border stabilizing and reinforcing member for use in mattresses. A plurality of rhomboid-shaped members of resilient material can be placed in the innerspring unit of a mattress between adjacent rows of springs. When placed as a beam between the springs, the rhomboid-shaped members improve firmness of the mattress. 
     Another approach involves a mattress border construction including a foam rail sleeve encasing a single row of coiled springs so that the top, bottom, and sides of the row of springs are surrounded by foam. Essentially, the coiled springs encased in the foam sleeve reinforce the border or edges of the innerspring unit giving it strength. 
     Moreover, in yet other approaches a mattress topper pad consisting of sheets of foam padding are provided wherein the soft foam is located in the middle of the sheet and the hard foam is located at the periphery or edges. Two or three of these sheets are laid on top of the innerspring unit. 
     Other conventional approaches involve including a bed guard comprising at least one elongated bolster assembled on top of a conventional mattress held in a position along one edge of the bed. A plurality of bolsters may be used on each edge of the bed for additional roll-off protection. Another design suggests using an array of pockets in which cylindrically shaped foam members are inserted to define a retainer structure enclosing a sleeping area on the mattress. Another conventional mattress design suggests using elastic foamed block inserts positioned into the void spaces left in the innerspring assembly at the periphery of the mattress. Other designs include a mattress topper pad and border stabilizer means for mattress innerspring units. The topper pad portion overlies the top or bottom of the coil innerspring unit while the border stabilizer portion is inserted between at least one convolution of each coil on the outside row of the coil innerspring unit to stiffen the spring action of the coils. 
     Certain of the conventional designs do not include a quilted, pillow top mattress. Such a mattress does not permit a top cover to move in from the edges of the mattress and therefore creates a drum effect. Consequently, the construction of the mattress works against itself in that a sleeper does not completely benefit from mattress substructure providing comfort and response to weight distribution (such as springs), but rather the sleeper lies upon a drum-like surface. 
     Further, conventional pillow-top mattresses typically include a gusset extending around a perimeter of the mattress. The gusset acts like a hinge which therefore allows the mattress cover to draw up about a sleeper. However, such conventional pillow-top mattresses require an extra layer of fabric between the mattress inner spring unit and the top upholstery which creates a drum effect within the body of the mattress. Although the drum effect is moved deeper within the mattress as compared to other conventional non-pillow top mattresses, the sleeper nevertheless does not completely benefit from the full comfort and functionality of the inner spring assembly. Another disadvantage of these conventional pillow-top mattresses is that they have become very thick (15-20 inches) in order to overcome the internal drum-like structure which makes it more difficult to find and fit sheets. Also, there exists a greater propensity for sagging mattresses and mattresses developing depressions. 
     Moreover, the multiple layers of upholstery or other materials included to create a barrier between bed springs and a sleeping surface adds to the material cost of a mattress. To offset material costs, manufacturers may select lower quality raw materials which do not stand the test of time. The undesirable permanent depressions can more readily form in the sleeping surface produced from the cheaper materials, which thus limits the life of a bed or at the very least, effects the long-term comfort of the bed. 
     Accordingly, there is a need for a mattress which both addresses the drum effect problem as well as provides a comfortable mattress having a long useful life. The present invention satisfies these and other needs. 
     SUMMARY OF THE INVENTION 
     Briefly, in general terms, the present invention is directed towards a mattress design embodying structure for optimizing comfort. Due to a novel construction approach, higher quality materials can be employed in the manufacture of commercial embodiments of the present invention. 
     In one particular embodiment, the mattress of the present invention lacks a taut or tension barrier between an inner spring assembly and upholstery layers forming a top surface of the mattress. The drum-like effect is minimized by the manner in which the border materials are affixed to the encasement of the mattress design. 
     In another aspect, the mattress includes a foam encasement that contains an inner spring assembly. Each spring of the inner spring assembly is individually wrapped and is capable of acting independently. Pockets or sleeves covering adjacent wrapped coils can be attached to each other. A border assembly extends about a perimeter of the foam encasement and includes an inner layer which is affixed directly to the encasement. The perimeter of an upper upholstery layer is attached to an upper end of the border assembly. Additionally, a plurality of fasteners are provided to connect the upper upholstery layer to the bottom portion of the foam encasement. 
     Without forces associated with pulling edges of the upper upholstery layer down to meet the perimeter of the mattress encasement, the mattress of the present invention is provided with a stable perimeter. The stability of the perimeter is further enhanced by the foam encasement arrangement. Such a stable perimeter results in minimizing any roll-off effect in that a sleeper can lie close to a mattress edge without being urged off the bed. 
     A higher category of materials can be used in the construction of the mattress of the present invention since fewer layers of upholstery are required to construct a comfortable and stable mattress. Better materials in turn provide the customer with a better product at a competitive price. Likewise, the life of the mattress can be increased as the formation of permanent impressions can be delayed or avoided through the use of superior raw materials. 
     Other features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective and partial cut-away view, depicting the various components of an assembled mattress of the present invention; 
         FIG. 2  is a cross-sectional view, taken along line  2 - 2  of  FIG. 1 ; 
         FIG. 3  is an enlarged and partial cut-away view, depicting components of the inner spring assembly; 
         FIG. 3   a  is a top view, depicting coils aligned in rows and columns; 
         FIG. 3   b  is a top view, depicting nested coils; 
         FIG. 4  as a cross-sectional view, depicting components of a border assembly; 
         FIG. 5  is a cross-sectional view, depicting the components of  FIG. 4  in assembled form; 
         FIG. 6  is a cross-sectional view, depicting a mattress assembly including a border assembly attached thereto; and 
         FIG. 7  is a cross-sectional view, depicting the mattress assembly of  FIG. 6  receiving top layers of upholstery. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, which are provided by way of example and not limitation, the present invention is embodied in a novel mattress design. The various components of the present mattress design are selected and assembled in a manner intended to provide a mattress of superior quality and which minimizes a drum effect found in conventional mattresses. 
     With reference to  FIG. 1 , there is shown a mattress  50  having an upper side or sleeping surface  54  and a lower or bottom side surface  56 . The mattress further includes a perimeter consisting of sidewalls  58  extending vertically from the bottom surface  56  to thereby define a generally rectangular three dimensional mattress structure. 
     In one aspect, the mattress  50  includes a foam encasement  60  which forms an understructure of the bottom  56  and sidewalls  58  of the generally three-dimensional rectangular shape of the mattress  50 . The foam encasement  60  can be made from various conventional materials such as polyurethane or other foams. Irrespective of the material, it is intended that the foam encasement  60  have a resilient and firm consistency to provide sufficient structure at the perimeter of the mattress to address the roll-off issue. Further, the foam encasement  60  can be formed from multiple components affixed to each other or can be constructed from a single piece of foam. 
     As shown in the Figures, the foam encasement  60  defines an open rectangular box. The foam encasement  60  includes a generally planar base  62  and two long, foam sidewalls  64  and a pair of short, foam sidewalls (not shown). The long sidewalls  64  are arranged parallel to each other and extend vertically from the base  62 . The short sidewalls also extend vertically from the base and are attached or formed at right angles with respect to the long sidewalls  64 . Thus, the sidewalls define a generally rectangular interior space for retaining other components of the mattress  50 . 
     The interior of the foam encasement  60  is sized to receive an innerspring assembly, which can assume various conventional or other forms. In one embodiment, the innerspring assembly includes a plurality of coils  80  (see also  FIGS. 2 and 3 ) arranged adjacently and extend vertically from the base  62  of the foam encasement  60 . It is to be recognized that various embodiments and configurations of springs can be used as a coil  80 . The coils  80  are contemplated to be individually wrapped in a sleeve  84  and to fill the entire interior of the foam encasement  60 . Moreover, the coils  80  are contemplated to act independently to provide support to a sleeper. As such, the coils  80  can be aligned in laterally extending rows or columns or can be offset or nested as desired to provide an intended firmness of a particular consistency. 
     As shown in  FIG. 3 , all or a selected number of the independently wrapped coils  80  can be affixed to one or more adjacent coils. One approach to affixing adjacent coils is to glue or tie the sleeves  84  of one coil  80  to another wrapped coil  80 . Again, by selectively connecting adjacent coil assemblies, a desired character or resiliency and spring force can be provided by the innerspring assembly. Moreover, as stated, the springs can be arranged in rows as depicted in  FIG. 3   a  or can be arranged so that they are nested as shown in  FIG. 3   b . When in a nested configuration, the coils  80  form a substantially full blanket of coils  80  effectively spreading a load across a mattress surface wherein, the adjacent coils  80  act to provide lateral support to each other and to minimize the bending or tilting of a particular coil  80 . 
     Referring again to  FIG. 1 , in one embodiment, the coils  80  can be made to extend vertically to substantially match or extend slightly higher than the height of the sidewalls  64 . Placed directly on top of the spring assembly are various layers of rectangular material forming upholstery layers. Upholstery layers are sized to extend across an outer perimeter of the foam encasement  60  and over the interior  70  of the foam encasement  60 . The upholstery layers are not, however, affixed to each other or pulled tight across the foam encasement  60 . Therefore, a taut or rigid barrier is not formed across the interior  70  of the foam encasement  60 . Rather, the peripheral ends of the layers lie over a top surface  90  of the sidewalls  64 ,  66 . In this way, a drum effect is avoided and the roll-off issue is addressed. 
     A first thin, sheet layer  100  made from soft stretch knit material is placed adjacent and to overlay the wrapped coils  80 . Lying on top of the sheet layer  100  is a first soft foam layer  102  made from latex polyurethanes or visco-elastic or slow recovery foam or cotton or polyester materials. The first soft foam layer  102  includes a generally planar bottom surface and a top surface including a plurality of undulating hills  103 . Placed on top of the first soft layer  102  is a second layer  104  which is constructed from cotton or equivalent materials. On top of the second layer  104  is a latex foam or other upholstery material layer  106 . Finally, a quilted panel  108  is placed on top of the wool layer  106 . 
     The quilted panel layer  108  can include various layers of material such as high quality wool and is intended to define the surface upon which the bed sheets are placed. Quilted to an underside of the quilted panel layer  108  is a stretch knit fabric which functions to also eliminate any drum effect in that area. A similar quilted panel layer can be employed as a border assembly or side panels  120  which are intended to surround and encompass the sidewalls  64  of the foam encasement  60 . Such material attached or extending from the sidewalls  120  is also contemplated to cover the base  62  of the foam encasement  60 . 
     Significantly, the border assembly  120  include a first outer layer  122 , a second middle layer  124  and a third inner layer  125  (See  FIGS. 2 ,  4 ,  5 ). These layers extend upwardly along the sidewalls  64 . The second inner layer  124  is attached directly to a top surface  90  of the sidewall  64 . The first layer  122  extends upwardly beyond the top surface  90  and includes a perimeter  132  that is attached by conventional means to a perimeter  134  of the quilted panel  108 . 
     As shown in  FIG. 2 , the top surface  150  of the mattress  54  is anchored or tethered to the base or bottom  56  of the mattress. Although various approaches are contemplated, in one embodiment, a pair of buttons or tufts  152 ,  154 , one residing on the top surface  54  and the other placed adjacent to the bottom surface  56  are connected by a lead  156 . Incorporating a plurality of such structure into a mattress design can add to the overall stability of the mattress construction. 
     The overall design of the mattress  50  lends itself to the use of fewer but higher quality materials. Further, by employing fewer upholstery layers, conventional sheet covers fit better yet the comfort of the mattress is not compromised. In a contemplated embodiment, the mattress is on the order of 12-14 inches thick. Additionally, it is to be recognized that by avoiding applying downward tension on the upholstery layers, both the drum effect and roll-off can be minimized. 
     The mattress  50  of the present invention can be assembled in various stages. As shown in  FIGS. 4 and 5 , one stage of assembly involves forming the border assembly  120 . The first fabric layer  122  and the second foam layer  124  are first sewn together. Next, the first and second layers are sewn to a polyester fiber and non-woven backing  125 . At the same time, a flange  172  is sewn at a plurality of positions to complete the assembly of the border  120 . 
     With reference to  FIG. 6 , the border assembly  120  is then attached to the foam encasement  60 . A lower portion  176  of the border assembly  120  is attached to the encasement  60  at a first location  180  via gluing and or divergent staples  182 . An upper portion  184  of the border assembly  120  is likewise attached via gluing and/or staples  182  to a second location  186  of the encasement  60 . It is also to be recognized that the upper portion  184  of the border assembly  120  can be attached to a border wire (not shown) of a mattress unit. 
     Once the border assembly  120  is so attached to the foam encasement  60 , a cavity  188  is created for filling with top layers of the mattress  50 . Extending across a base of the cavity  188  is the sheet layer  100  of soft stretch knit material configured over the mattress unit including the spring assemblies  80 . Due to the approach of design contemplated, this layer  100  of material need not be placed in tension which consequently facilitates the optimum performance of the springs  80 . As such, the springs  80  are allowed to act independently being unconstrained by a fabric or other layer of material and thus, are permitted to react with greater flexibility and versatility to the distribution of weight across the mattress surface. 
     A final step of assembly involves filling the cavity  188  with the top layers  102 ,  104 ,  106  of the mattress assembly  50  (See  FIG. 7 ). These layers are then tufted to the bottom  56  of the mattress using the button/tether  152 ,  154 ,  156  or equivalent anchoring arrangement. Moreover, edges of the quilted top layer  106  are sewn about the perimeter of the mattress to the border assembly  120  to thereby form a completed mattress assembly  50 . 
     Thus, it will be apparent from the foregoing that, while particular forms of the invention have been illustrated and described, various modifications can be made without parting from the spirit and scope of the invention.