Patent Publication Number: US-6212720-B1

Title: Mattress tub

Description:
BACKGROUND OF THE INVENTION 
     The invention is directed to a mattress tub which forms the upper support portion of a mattress and can as well form a lower support portion which essentially becomes uppermost when the mattress is turned or flipped in the customary fashion. The construction of the mattress tub directly affects the comfort and “feel” of the mattress because it is the support portion upon which a sleeper or patient rests and is thereby supported. 
     Upper support portions of the type described are relatively common, as is reflected by the disclosure of U.S. Pat. No. 5,317,768 in the name of Alvin R. Klancnik granted on Jun. 7, 1994. This patent discloses a mattress which is formed by a coil spring structure, a bottom cloth layer thereabove, next a convoluted foam layer having upwardly directed peaks and upwardly opening valleys, and spanning and covering all the latter are an upper fiber layer and an outermost cloth layer with all of the components, excluding the coil spring structure, being held together by stitching. The patent recognizes inherent problems in a mattress of this type, such as the crushing of the fiber material which causes a loss in resilience and prevents the same from returning to its original position even after weight has been removed. Another disadvantage of the mattress is said to be the retention of moisture by the top surface should a sleeper perspire. Once wet, the fiber is slow to dry and the retained moisture is said to result in an unpleasant aroma. The problem of such mattresses is resolved by the patent disclosure through the utilization of the convoluted foam layer, located beneath the fiber layer, having upwardly directed peaks which are partially compressed when weight (a person or sleeper) is applied thereto and which return to their no-load position once weight is removed. This is said to move or exercise the fiber layer thereby reducing matting and also forces air movement which dries any moisture from the fiber layer. The convoluted foam layer in the top surface also increases the comfort or softness of the mattress since the peaks are quick to respond to a weight by compressing. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a mattress which includes a mattress tub which not only provides all of the advantages of known prior art mattress tubs, but also provides comfort, feel and softness comparable to mattresses constructed entirely of foamed latex which are recognized in the trade as superior mattresses at the high end of comfort and cost. The mattress tub of the invention substantially eliminates the quick peak compression of known mattresses of the type described utilizing a convoluted foam layer and instead achieves progressive compression toward full compression through the utilization of a plurality of randomly sized pieces of foamed latex or latex foam housed within and substantially filling the valleys of the convoluted foam layer. In this fashion when weight is applied to an upper surface of the mattress and the mattress tub thereof, the plurality of randomly sized pieces of foamed latex are progressively themselves moved intimately against one another into a mass and as the peaks of the convoluted foam layer compress, the pieces of foam latex also progressively compress thereby providing progressive compression toward full compression which in turn provides superb comfort through automatic ergonomic contouring of the mattress pad to both the shape and weight distribution of a person lying thereupon. For example, the portion of the mattress tub underlyingly supporting the hips of a person would be compressed the most, the shoulder portion of the sleeper next most, and the feet and head of the sleeper the least. Hence, the peaks of the convoluted latex foam layer in the area of the person&#39;s hips would be compressed to a maximum, the valleys reduced correspondingly in height, and the pieces of foamed latex similarly being compressed closer together as a mass and also being individually compressed which effectively produces the same desirable functions of a solid foam mattress at an appreciably lessened cost. (Scrap latex foam pieces are relatively inexpensive.) Thus, the mattress tub of the invention when utilized with a coil spring produces a mattress having the most desirable characteristics of the most expensive foamed latex mattresses yet provides the same at an appreciably lesser cost, both wholesale and retail. 
     In further accordance with the present invention, the pieces of foamed latex can be preferably selectively deposited in the valleys to achieve variable compression zones which provide the ultimate in mattress tub comfort in accordance with the present invention. Desirably, a mattress tub might, for example, be divided into five compression zones, namely, a head compression zone, a shoulder compression zone, a hip compression zone, a leg compression zone, and a foot compression zone. By providing different amounts of the foamed latex pieces in the valleys of these different compression zones, the eventual mattress utilizing the mattress tub would provide ultimate underlying support and comfort to a person/user. However, though the latter is desirable, it is recognized that mattresses are not only turned over but are also rotated end-for-end. Thus, the mattress tub is essentially “divided” into three compression zones, namely, a central shoulder/hip compression zone, a head compression zone at one side thereof, and a leg/foot compression zone at an opposite side thereof. By introducing more pieces of foam latex into the shoulder/hip compression zone than in the opposite head and leg/foot zones, which can have equivalent pieces of foamed latex housed therein, the mattress tub provides maximum resistance to compression/weight at the shoulder/hip compression zone and minimum resistance to compression/weight at the remaining compression zones. The overall effect of such a compression zoned mattress tub is to provide essentially uniform softness and feel over the entire length of the mattress tub and an associated mattress, once again providing ultimate comfort to the user. 
     With the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claims and the several views illustrated in the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a fragmentary perspective view of a portion of a mattress, illustrating in solid lines a bottom polymeric/copolymeric layer, a polymeric/copolymeric frame, a convoluted latex foam layer within the frame, pieces of foamed latex in valleys of the convoluted layer, and a top layer closing the tub. 
     FIG. 2 is an enlarged fragmentary cross-sectional view taken generally along line  2 — 2  of FIG. 1 showing only the mattress tub, and illustrates the manner in which the valleys of the convoluted latex foam layer are filled with pieces of foamed latex material with the upper or top layer confining the pieces in the valleys to prevent migration thereof. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A novel mattress constructed in accordance with this invention is fully illustrated in FIG. 1 of the drawings and is designated by the reference numeral  10 . 
     The mattress  10  is defined in part by a mattress tub  20 . 
     The mattress tub  20  includes a centrally located generally rectangularly contoured convoluted foamed latex layer  30  having opposite generally parallel ends (not shown) and generally opposite parallel sides (unnumbered). The convoluted latex foam layer  30  also includes a substantially flat lower surface  31  and an opposite convoluted upper surface  32  defined by upwardly directed peaks  33 , each having a terminal end (unnumbered) and upwardly opening valleys  34 . 
     The convoluted latex foam layer  30  is peripherally bordered by a frame  40  of polymeric/copolymeric material, such as polystyrene. The frame  40  includes opposite side frame members  41 ,  42  which are in generally parallel relationship to each other and between which are sandwiched spaced generally parallel end frame members of which only one end frame member  43  is illustrated in FIG. 1 of the drawings. Frame members  41  through  43  are of a substantially polygonal transverse cross-sectional configuration, as is best indicated by the frame member  41  of FIG.  2 . Opposite end surfaces of the end frame member  43  abut and are adhesively bonded to the side fame members  41 ,  42 , as is the opposite unillustrated end frame member thereby unifying the four frame members into the one-piece polygonal frame  40 . 
     The lower surface  31  of the convoluted latex foam member  30  and a lower surface  44  of the frame  40  are bonded to an upper surface  51  of a lower layer  50  of polymeric/copolymeric material, such as polystyrene. 
     The valleys  34  of conventional mattresses and/or mattress pads are devoid of material and simply define air spaces. However, in accordance with this invention each of the valleys  34  is partially or fully filled with a plurality of randomly sized pieces of foamed latex  60 . The valleys  34  with the latex foam pieces  60  therein are closed by an upper or top layer  70  of polymeric/copolymeric material, such as polystyrene. A lower surface  71  of the top layer  70  contacts the tops (unnumbered) of the peaks  33  and an upper surface (unnumbered) of the frame  40 . The lower surface  71  of the upper layer  70  is preferably bonded to the upper surface (unnumbered) of the frame  40  and, if desired, the lower surface  71  of the upper layer  70  can also be bonded to the uppermost surfaces (unnumbered) of the peaks  33 . 
     The mattress tub  20  rests with the lower layer  50  upon a conventional coil spring structure  80  which includes a number of coil springs united to each other and to upper and lower polygonal frames in a conventional manner. A lower mattress tub corresponding identically in structure to the mattress tub  20  is identified by the reference character  20 ′, but the latter is in inverted relationship to the coil spring structure  80 , as compared to the mattress tub  20 . In other words, the peaks and valleys (not shown) of the mattress tub or lower mattress tub  20 ′ respectively project and open downwardly whereas the peaks  33  and the valleys  34  of the mattress tub  20  respectively project and open upwardly. Thus, the mattress  10  can be turned or flipped top-for-bottom, vice versa, and end-for-end. 
     Following conventional practice, a cover of cloth or fabric encases the upper mattress tub  20 , the coil spring structure  80  and the lower mattress tub  20 ′, and the latter is generally designated by the reference numeral  85  with appropriate stitching  86  being utilized in a conventional manner to unify all components into the mattress  10 . 
     It is because of the plurality of randomly sized pieces of foamed latex  60  substantially filling the valleys  34  of the convoluted layer  30  which allows what might be best described as progressive compression toward full compression under the weight of a person or sleeper upon the mattress  10 . In other words, as a person lies upon the mattress  10 , the peaks  33  progressively compress and the compression of the individual peaks  33  varies depending upon the portion of the body of the person lying directly thereabove. As can be readily appreciated, a person hips and mid-section more often than not carry appreciable weight and, therefore, the peaks  33  in these areas are compressed the most in a progressive fashion toward total compression. As the compression of the peaks  33  begins, it is resisted by the pieces of foamed latex  60  which also are progressively compressed or are initially forced more compactly toward each other as a group and thereafter are individually and as a group progressively compressed. Thus, over any particularly area of the mattress  10  upon which a person rests, the peaks  33  and the plurality of randomly sized pieces of foam latex  60  underlying the person progressively compress until a point is reached at which compression ceases and the individual is appropriately softly supported by the overall mattress and particularly the cumulative effects of the progressively compressed peaks  33  and the progressively compressed foam latex pieces  60 . The foam latex pieces  60  compress, yet at the same time they resist the compression of the peaks  33 , as opposed to the absence of material of any kind in the valleys  34 . Under heavy weights, the peaks  33  are compressed the most and the resistance to such compression afforded by the foam latex pieces  60  is at a maximum, whereas under lighter weights the peaks  33  compress less and the resistance offered against such compression by the foam latex pieces  60  is correspondingly reduced. The overall effect of the combination of the peaks  33  and the foam latex pieces  60  is to achieve progressive resistance to compression of the peaks under the influence of different weights of persons supported upon the mattress  10  thereby imparting softness comparable to mattresses constructed entirely of solid unconvoluted latex foam. However, the mattress  10 , because of the construction of the mattress tub  20 , is appreciably less expensive than a mattress constructed entirely of latex foam material while offering comfort and softness equivalent thereto. 
     In lieu of filling all of the valleys  34  with pieces of foam latex  60 , the valleys  34  can be selectively filled depending upon the weight which is applied to the mattress  10  by a person and the progressive resistance one wishes to offer counteracting such weight. For example, the valleys  34  in a mid-transverse one-third of the mattress could be completely filled with the latex foam pieces  60 , whereas the head one-third and the foot one-third ends would be partially filled to provide zones of varying resistance to the progressive compression of the peaks  33 . 
     Although a preferred embodiment of the invention has been specifically illustrated and described herein, it is to be understood that minor variations may be made in the apparatus without departing from the spirit and scope of the invention, as defined the appended claims.