Patent Abstract:
A bed construction having a one-sided mattress assembly supported on a rigid foundation. The one-sided mattress assembly includes a core of pocketed coil springs having a layer of resiliently compressible material covering the upper surface thereof and having a bottom surface constructed of a substantially rigid material without a compressible layer. The core of coil springs is attached to the bottom surface around its periphery. The foundation has a rigid inner construction and a noncompressible top layer. The bed construction reduces the amount of compressible padding in the mattress by one-half and consequently the mattress is capable of exhibiting a substantial reduction in the amount of permanent deflection in use.

Full Description:
RELATED APPLICATIONS 
     This application is a continuation of Ser. No. 09/742,126 file date Dec. 22, 2000, now U.S. Pat. No. 6,408,469, issued Jun. 25, 2002, which is a continuation-in-part of Ser. No. 09/482,591 file date Jan. 13, 2000, now U.S. Pat. No. 6,243,900, issued Jun. 12, 2001, all of which are incorporated herein by referenced in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to a bed construction, and more particularly to a bed construction having a one-sided mattress assembly supported on a rigid foundation that offers significant reduction in the amount of permanent deflection or sagging of sleeping surface of the mattress. 
     A conventional inner spring mattress as known in the bedding industry generally comprises a resilient construction consisting of two sleep surfaces (a top layer and a bottom layer) enclosing an assembly of wire springs. The wire springs are typically covered with padding layers on the top and bottom surfaces, and the whole assembly is encased within a ticking, often quilted, that is sewn closed around its periphery to a border or boxing. For many years, one form of spring assembly construction has been known as Marshall construction. In Marshall construction, individual wire coils are each encapsulated in fabric pockets and attached together in strings which are arranged to form a closely packed array of coils in the general size of the mattress. Examples of such construction are disclosed in U.S. Pat. Nos. 685,160, 4,234,983, 4,234,984, 4,439,977, 4,451,946, 4,523,344, 4,578,834, 5,016,305 and 5,621,935, the disclosures of which are incorporated herein by reference in their entireties. 
     Conventionally, inner spring mattresses, with either pocketed coils or open coils, have had identical top and bottom layers. During normal life of such conventional mattresses some degree of permanent deflection, or sag, can develop in the mattress surfaces due to compaction of the component padding materials in the top and bottom layers. This permanent deflection can interfere with the mattresses&#39; intended function of providing a supportive and resilient sleep surface. Inner spring mattress manufacturers recommend periodically rotating and turning over the mattress thereby utilizing the top and bottom sleep surfaces in order to counteract, minimize, and/or delay the aforementioned permanent deflection or sag. Under continued use, this compaction or sag becomes more permanent. The degree of permanent deflection is directly related to the type and amount of padding installed both over and under the wire spring core assembly. To remedy this shortcoming, manufacturers utilize materials that produce less permanent compaction. These materials are generally more dense but can be less comfortable and more expensive. 
     Conventional foundations, such as box springs, often contributed to the problem of sagging by providing a compressible top layer. Any additional compaction of the top layer of the foundation contributes to the overall sagging of the sleeping surface of the mattress. 
     Accordingly, it is desirable to provide a bed construction having an inner spring mattress assembly which exhibits a reduced amount of permanent deflection due to compaction of padding materials while at the same time exhibiting substantial comfort in use. It is further desirable to provide a mattress assembly that can be constructed by conventional known manufacturing techniques. Still further, it is desirable to provide a mattress assembly that is cost-effective to produce. 
     SUMMARY OF THE INVENTION 
     The present invention improves over the prior art by providing a bed construction with a one-sided mattress assembly supported on a rigid foundation. The one-sided mattress assembly includes a core of wire springs including, but not limited to, pocketed or open coil springs. The spring core of the mattress is covered by a layer of resiliently compressible material covering the upper sleeping surface thereof. The spring core of the mattress is supported on a bottom layer constructed of a substantially rigid material that is not generally compressible. The core of coil springs is attached to the bottom layer around its periphery. The rigid bottom layer of the mattress assures firm support for the coil springs and thereby reduces sagging that may result from the springs being poorly supported by the compressible padding under the springs of a conventional two-sided mattress. 
     In connection with the present invention, the padding for the top layer is selected to resist permanent compaction or deflection. Moreover, padding is only needed on the top layer of the mattress thereby reducing by one-half the amount of padding required. Consequently, the mattress construction of the present invention with a padded top layer and a rigid bottom layer necessarily reduces the amount of material that is subject to permanent compaction and therefore reduces the amount of permanent deflection of the mattress overall. Maintenance of the mattress of the present invention by rotating or turning the mattress over is also avoided. 
     In order to further reduce sagging of the sleeping surface of the mattress, a rigid foundation is provided to give further support to the rigid bottom layer of the one-sided mattress and therefore the spring core. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other novel features and advantages of the invention will be better understood upon a reading of the following detailed description taken in conjunction with the accompanying drawings wherein. 
     FIG. 1 is an exploded cross-section view of a conventional two-sided inner spring mattress; 
     FIG. 2 is an exploded cross-sectional view of a one-sided inner spring mattress constructed according to the principles of the invention; 
     FIG. 3 is a schematic plan view of a complete assembly of Marshall coils for use in the mattress construction according to the present invention illustrated in FIG. 2; 
     FIG. 4 is a partial perspective view, partly broken away, of the Marshall coil assembly illustrated in FIG. 3; and 
     FIG. 5 is a partially exploded elevation view of a foundation used in connection with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, and initially to FIG. 1, a conventional two-sided mattress is illustrated in exploded cross-section and designated generally by the reference numeral  10 . The conventional mattress  10  includes as a principal component a wire spring assembly  12  of Marshall spring coils, as will be described in detail hereinafter and which comprises the central core of the mattress  10 . The mattress  10  could also incorporate an assembly of open coil springs or other wire inner springs. The mattress  10  has an upper sleep surface  14  and a lower sleep surface  16 , and therefore, is of a conventional type intended to be turned over periodically to help minimize compaction of its padding material and the resulting sagging of the mattress  10 . Padding material  18 , which is identical on both sides  14  and  16  includes a layer of closed-cell foam such as polyurethane. Covering the material  18 , on both sides of the mattress, is a ticking layer  20  which may be quilted and which may include additional foam in a manner well-known in the art. The ticking layers  20  are fastened such as by sewing to a border  22  which extends around the entire periphery of the core  12  of coil springs. 
     Turning now to FIG. 2, a mattress  30  constructed according to the invention is shown in exploded cross-section. The mattress  30 , like the conventional mattress  10  illustrated in FIG. 1, has a central core  12  of the Marshall coils. The mattress  30 , however, may have a central core  12  comprising open coil springs or other wire springs. An upper sleep surface  34  is formed over the central core  12  by a layer of foam padding  18  and a layer of ticking  20 . In accordance with the invention, however, the mattress  30  has an underside  36 , positioned under the central core  12  and which comprises a substantially rigid layer  38  of material covered by a thin layer  40  of a non-woven sheeting. A border  42  connects the ticking  20  and sheeting layer  40  and extends around the periphery of the coil spring assembly  12 . A lower border wire  44  is secured to the coil spring assembly  12  around its periphery as well as to the layer  38  such as by hog rings  46 . 
     FIGS. 3 and 4 illustrate one form of mattress core  12  of the aforementioned Marshall coil construction. In this construction, closely positioned coil springs are aligned in a string assembly  50  (FIG. 4) wherein individual springs  52  are each encapsulated within a pocket of  54  of fabric material  56  which may be sewn or ultrasonically welded to create the pockets  54  and to create a unitary Marshall coil type assembly  12 . An example of such construction is more fully disclosed in U.S. Pat. No. 5,621,935 which is commonly assigned herewith and the disclosure of which is incorporated herein by reference in its entirety. A person of ordinary skill in the art will appreciate that opened coil springs or other wire springs may be used for the mattress core  12  as well as Marshall coil springs. 
     As previously described, the sleeping surface  34  comprises a layer of foam padding  18  and a layer of ticking  20 . The ticking  20  is of conventional construction. In accordance with the present invention, however, the foam padding  18  is specifically selected to provide comfort yet minimize compaction. Particularly, the foam padding  18  is a high density polyurethane foam having a density from about 1.0 lbs./cu. ft. to 2.5 lbs./cu. ft. The foam layer  18  also has a firmness in a range of between 10 and 55 ILD, where “ILD” refers to the standard Indented Load Deflection test. Within the ranges specified, the foam padding  18  for the sleeping surface  34  is selected to provide varying degrees of firmness or softness to accommodate individual preferences. 
     The relatively rigid bottom layer  38  is a high density polyurethane foam having a density of approximately 1.85 lbs./cu. ft. The foam layer  38  also has a firmness above 30 ILD. In practice, an ILD above 55 has proven to be most effective based on considerations of cost and durability. Other rigid materials may be used in place of the foam layer  38 . Such materials may include solid plastic, wood, or other nonyielding rigid materials. To the extent such materials for the layer  38  yield to pressure, such materials must have at least a high degree of recoverability once the pressure has been removed so that the materials are not compacted. 
     Turning to FIG. 5, there is shown a foundation  60  for use in connection with the construction of a bed in accordance with the present invention. The most important aspect of the foundation  60  for the present invention is providing a rigid top surface  62  to support the mattress  30  (FIG.  2 ). Rigid support of the mattress  30  by the foundation  60  further reduces the amount of sagging of the sleeping surface  34 . In order to achieve rigid support of the mattress  30 , the foundation  60  is constructed in accordance with the disclosure of commonly assigned U.S. Pat. No. 5,940,908, and particularly FIG. 6 of that patent. 
     The foundation  60  has a structural frame  64 . The structural frame  64  has a rectangular border including a pair of side rails (only rail  66  is shown in FIG.  5 ). The side rails may be formed from standard lumber of construction grade in nominal 1×3 size, connected at a head end of the frame  64  by a head end rail  68  and at the foot end of the frame  64  by a foot end rail  70 . The end rails  68  and  70  may be formed, for example, from a lower 1×2 end filler slat which butts the side rails in the plane thereof. Cross slats  72 ,  74 ,  76 ,  78 ,  80 ,  82 , and  84  are positioned on the upper surfaces of the side rails and extend laterally to span the transverse distance between the side rails. Optionally, a longitudinally extending center support rail may be attached to an undersurface of the head and foot rails  68  and  70  and secured to an underside of each of the cross slats  72 - 84  to provide additional structural integrity and strength for the frame  64 . 
     As further illustrated in FIG. 5, it will be seen that cross slats  80 ,  82 , and  84  are centrally positioned along the length of the frame  10  and have an L-shaped cross-section configuration. However, it should be noted that the L-shaped cross slats may be positioned elsewhere along the length of the frame  64  or be employed in a lesser or a greater number. The L-shaped cross slats  80 ,  82 , and  84  act as reinforcing braces or beams to reduce deflection of the frame  64 . 
     As illustrated in FIG. 5, the non-resilient bedding foundation  60  has a mattress support assembly  86 . The mattress support assembly  86  comprises a plurality of wire support members  88  supported on and attached to the cross slats  68 ,  70 ,  72 ,  74 ,  76 ,  78 ,  80 ,  82 , and  84 . In this embodiment, a top layer  63  is applied over the assembly  86  and a cover or ticking  90  is provided to form the exterior surface for the entire foundation  60 . The top layer  63  is similar in construction and performance to the bottom layer  68  of the mattress  30 . Particularly, the top layer  63  is designed to provide a rigid support surface for the mattress  30  with a firmness above 30 ILD and specifically above 55 ILD. 
     The one-sided inner spring mattress  30  constructed according to the invention offers considerable advantages over prior art conventional two-sided mattresses in terms of reducing the amount of permanent deflection of the sleeping surface due to undesirable compaction of padding materials. Because the mattress  30  essentially has a 50 percent reduction in padding due to the rigid bottom layer  38 , the coil assembly  12  does not settle into and compact a lower padding layer as would happen with a two-sided mattress of conventional construction having identical padding layers on both sides. The addition of a rigid foundation beneath the one-sided mattress  30  also provides additional support for the coil springs of the mattress  30  and thus helps further reduce sagging. 
     The one-sided mattress  30  of the invention also offers the advantage of eliminating maintenance of the mattress by periodically turning it over as is recommended for conventional two-sided mattresses. Accordingly, the one-sided mattress  30  is more convenient for the consumer to use. Further, the Marshall coil construction or open spring construction use conventional materials so that the one-sided mattress  30  may be readily manufactured by techniques that are well known in the industry. The foundation  60  likewise can be constructed using conventional manufacturing techniques. 
     While the present invention has been described in connection with certain embodiments thereof, it will be apparent to those skilled in the art that many changes and modifications can be made without departing from the true spirit and scope of the present invention. Accordingly, it is intended by the appended claims to cover all such changes and modifications as come within the scope of the invention.

Technology Classification (CPC): 0