Patent Application
20080078029
With reference to
In particular, peripheral skirt 9 comprises extension side panels 11 that may be integrally formed as unitary parts of the main piece of material forming top panel 3, and composite end panels 13. Composite end panels 13 comprise extension end panels 15, that may be formed as integral unitary parts of the main piece of material forming top panel 3, and separately formed, attached stretch end panels 17. Stretch end panels 17 are attached along their respective upper edges to the corresponding peripheral edges of the extension end panels 15. As will be described in further detail, this attachment is effected while maintaining the attachment edge of the partial end panels under tension in a longitudinally stretched condition. As such, upon being permitted to relax, the recovery of the stretch material to its relaxed state draws the material inwardly upon itself and carries with it the peripheral edges of extension end panels 15.
Various relative sizes of the extension end panels 15 and stretch end panels 17 may be employed, depending, e.g., on the overall desired skirt depth and the materials used. In one example, where a total skirt depth of approximately 15″ is provided, approximately 10″ may be allocated to the stretch end panels and approximately 5″ may be allocated to the extension end panels (2:1 ratio).
In an exemplary embodiment, a single piece of material forms top panel 3, extension side panels 11, and extension end panels 15. That material may be a substantially inelastic and substantially non-stretchable material, e.g., of woven cotton (traditional muslin). Alternatively, this main piece of material may comprise a stretchable fabric; that fabric may or may not comprise elastic threads or cords. For example, the material may be of stretchable knitted cotton, of the type commonly used for T-shirts. As another possibility, the material could be a stretchable knit of wicking polyester. Regardless of the type of fabric used for the main piece of material, so long as the edges of the stretch end panels 17 are longitudinally stretched at the time of attachment to the main piece of material, the recovery of the stretch panel material following the attachment will cause the formation of gathers in the extension end panels 15 and a contraction of a central portion of top panel 3 (as generally illustrated in
The stretch of the stretch end panels 17, upon installation of sheet 1 on mattress 5, sets up recovery forces acting inwardly toward the center of the composite end panels 13. At its opposite ends, each of composite end panels 13 is attached to corresponding end edges of side extension panels 11. Hence, the recovery forces (which may be partial recovery forces) pull peripherally on side extension panels 11, thereby tending to remove any looseness or slack in the side extension panels that might otherwise exist by virtue of the mattress covering being sized to accommodate mattresses at the upper (as well as lower) end of a range of mattress peripheral dimensions and thicknesses. The stretch recovery forces transmitted to extension side panels 11 also tend to draw in bottom peripheral edge portions 19 of extension side panels 11 underneath mattress 5, as well as the bottom peripheral edges of stretch end panels 17, as illustrated in
In addition, the cap structure formed by extension end panels 13, and their corner attachment to extension side panels 11, further contributes to preventing undesirable shifting of the mattress covering on the mattress, by providing well defined corners for receiving the corners of the mattress.
While a similar effective gripping action is achieved with mattress covering configurations as described in the aforementioned Seago patents, this is at some expense with respect to the look and feel of the sidewalls and end walls. This is generally of no consequence for a mattress pad, which will typically be covered by a fitted sheet. However, as previously mentioned in the Background section, the sidewalls of a fitted sheet will typically be exposed to the user(s) of a bed upon the drawing back of blanket(s), bed spread(s) and the like. Thus, the look and feel of the sidewalls is generally more important in this application.
Advantageously, sheets constructed in accordance with the present invention afford the opportunity to maintain, on the mattress sidewalls, the same uninterrupted look and feel of the top panel of material, since the sidewall covering skirt portions can be constructed as uninterrupted continuations of the top panels. Moreover, even the end panels (which are typically much less likely to be exposed to the user than the side panels) can retain in substantial part the same look and feel as the top panel by virtue of the fact that the stretch end panels may be confined to a lower partial portion of the end(s) to which they are applied.
While in the illustrated arrangement the extension side panels and extension end panels are formed as unitary extensions of top panel 3, the extension side panels and extension end panels could instead be pieces of material formed separate from the material of top panel 3, and then attached thereto. Even in this case, the present inventive approach affords the advantage that aesthetics may dictate what those materials may be, since the gripping functionality will be achieved with the stretch end panel provided at partial lower portions of at least one, and preferably both, ends of the mattress. By confining the stretch panel to a smaller area of the skirt, it is also possible to realize cost savings, due to the potentially higher cost of the stretch material in comparison to the material(s) of the remainder of the sheet or other mattress covering.
At the same time, sheets and other mattress coverings in accordance with the invention can be constructed so as to exhibit advantageous grip and fit characteristics that rival those achieved with the mattress coverings of the aforementioned Seago patents. This is due, at least in part, to a method of manufacturing a mattress covering in accordance with an aspect of the invention, which permits stretch fabrics providing a significantly stronger longitudinal pull (recovery) force to be employed for the stretch panels, as will be explained.
As can be seen in
Various methods may be used to construct a mattress covering (sheet, mattress pad, etc.) in accordance with the invention. In order to make a mattress cover as illustrated, a substantially inelastic non-stretchable fabric material may be cut or otherwise formed into a main piece of material providing, as illustrated in
Now, with reference to
The attachment may be effected by sewing, and the sewing may be performed by an operator using a conventional serging sewing machine. In this case, the tensioning and stretching is preferably carried out in an incremental, edgewise fashion. Since it is only necessary to stretch an edge portion along the attachment seam, it is much easier for an operator to stretch a particular stretchable material during the sewing process, as compared to the case if the entire width of the stretch panel was being stretched.
In this regard, it is relevant to note that in existing methods of attaching a strip of elasticized material about the entire periphery of a mattress cover top panel, to form a longitudinally stretchable elastic skirt, such as in the case of the mattress covers of the aforementioned Seago patents, the skirt material is stored on rolls in an elastically stretched condition. The stretched state of the material is maintained (across its width) as it is fed into the sewing machine, and up to the point that it is stitched, with release occurring progressively thereafter. Under these circumstances, due to the fact that the tension forces generated by the entire width of the skirt material are transmitted to the presser foot and needle of the sewing machine, significant limits are placed on the stretch materials that could be used and/or the degree of stretch that could be imparted to the material, so as to avoid damage to the equipment. In accordance with an aspect of the present invention, this constraint is greatly reduced by stretching the material only along the edge portion that will form the attachment seam.
An example implementation of this technique is illustrated in
Due to its elongation during the process of attachment, the stretch panel, which preferably starts out significantly (e.g., 10-40%) shorter than the width of the extension end panel 15, becomes at least coextensive with the length of panel 15. As the stretch material of stretch end panels 17 is progressively attached to the peripheral edge of extension end panel 15, the stress or tension imparted to the attachment edge may be relieved, allowing the stretch material to longitudinally contract to a relaxed condition. If, when the seam reaches the end of the extension end panel, there is some excess length of the stretch material remaining, that may be trimmed off as the corners are formed (as described below), or thereafter.
Once stretch panels 17 have been attached to extension end panels 15 in the overlaid position shown in
Finally, the elastic strip 21 (see
A wide variety of stretchable materials may be used to form stretch end panels 17 of the inventive mattress covering. This includes, in addition to elastic materials having close to 100% recovery, stretch knit and like materials that have a limited but sufficient amount of recovery to impart a longitudinally directed pull-force on the ends of the side panels upon being stretched in order to fit the mattress covering on a mattress. Such materials may derive their stretchability from their integral inclusion of elastic threads, cords or fibers, or from a particular knit formula employed without components which are, per se, elastic. Additionally, the desired stretchability may be imparted to a substantially inelastic base fabric, e.g., using the techniques for stitching lines of elastic cord into a substantially inelastic base fabric disclosed in the aforementioned Seago patents. As another example, the stretch material could be a known-type elastically stretchable material formed as a laminate of non-woven elastic material sandwiched between a pair of substantially inelastic layers of material, such as described in the aforementioned Perfect Fit patent.
The stretchability of primary concern is stretchability in the longitudinal direction of the stretch end panel, so as to provide a circumferentially directed pull (recovery) force upon being installed on a mattress. In one embodiment, the material of the stretch end panels provides significant stretchability in this direction alone, being substantially non-stretchable in a transverse direction of the stretch end panels. Bi-directionally and even omni-directionally elastic/stretchable materials could also be used, however.
In one embodiment, the stretch panels are formed of a stretch woven material incorporating elastic yarns, e.g., spandex (such as Lycra), rubber or Dow XLA, extending in the longitudinal direction of the panels. The elastic yarns may comprise an elastic core covered with cotton, polyester or other fibers. One particular blend comprises 95% cotton and 5% spandex by weight. In another embodiment, the fibers are blended at a ratio of 80% cotton to 20% spandex by weight. Various fiber blends can be used with elastic or stretch yarns.
In a further embodiment of the invention, the stretch panels may be formed of a stretch knit or other elastic material that has yet to undergo a finishing process to impart stretchability to the fabric. Such a panel could be attached to the extension end panels in the manner previously described, except that the attachment, e.g., by stitching, would be without incrementally stretching the attachment edge of the material in the process. In this case, the stretchability of the stretch panels would not be imparted until a post-attachment finishing phase. Such a phase could, e.g., be a wash and dry cycle of a conventional laundry washing machine, or other heat treatment carried out by the manufacturer before packaging and sale, or by the consumer after purchase and prior to use. Since most consumers will wash new bed clothes prior to use in any event, the extra step of washing and drying fitted sheets to activate the stretch panels should not present a significant inconvenience. Such a finishing phase would serve to contract the stretch material, gathering with it the material of the extension end panels, to thereby render the material stretchable with longitudinal recovery forces capable of providing a tight fit and effectively gripping mattresses of a range of sizes upon installation, in the manner previously described. This process for imparting stretchability to a skirt portion is not limited to mattress covers with stretch panels provided only at the ends, but could also be applied to impart stretchability, longitudinal and/or otherwise, to a greater portion of the skirt or its entirety.
In the embodiments described thus far, the stretch end panels would, upon installation on a mattress, extend fully across the longitudinal dimension of the mattress end walls, being directly attached at their ends to corresponding end edges of the sidewall extension panels. This is not necessarily the case. In an alternative embodiment of the invention, the stretch end panels may comprises one or more panels that span less than the entire longitudinal dimension of the mattress end walls, with the remainder being covered by another material, e.g., a unitary extension of the extension end walls, or one or more separately formed and attached pieces of material (which need not be stretchable). As just one example of the many possibilities in this regard, a pair of approximately 10″ square panels of stretch material could be attached under tension in the general manner previously described, but so as to provide two relatively short stretch end panels at the ends of the composite end panel formed, one adjacent each of the corners and having a mitered seam connecting the panel to a corresponding end edge of a corresponding sidewall extension panel. In another embodiment, the stretch panels could be positioned inwardly of the corners such that their attachment to the end edges of the sidewall extension panels is indirect, i.e., through other material of the composite end panels.
The present invention has been described in terms of preferred and exemplary embodiments thereof. Numerous other embodiments, modifications and variations within the scope and spirit of the appended claims will occur to persons of ordinary skill in the art from a review of this disclosure.
