Abstract:
Laces for shoes, sneakers, or other wearing apparel that adjust easily, but stay tied. In one embodiment, the novel design is a flat lace having an upper and lower surface made from different materials. The surfaces have a relatively low coefficient of friction with respect to a shoe&#39;s eyelets. Upon being tied, the surfaces have a high coefficient of friction when they are in contact with one another. An alternative design includes a brush-like array of tiny fibers protruding from the lace surface. Another embodiment consists of a middle portion having material properties different from its end portions. An alternative design has two sets of opposing sides with different material properties. The inventive designs minimize the possibility of laces coming untied.

Description:
FIELD OF THE INVENTION 
     The present invention relates to laces for footwear and, more particularly, to shoe and sneaker laces that can be easily threaded, looped, and adjusted, but that retain a tight knot when tied. 
     BACKGROUND OF THE INVENTION 
     Laces can be tied tightly or loosely, depending upon the preference of the wearer. Even a custom-made shoe benefits from the adjustability provided by laces, since both the dimensions of a foot and the tightness/looseness preference can change in the course of the day. To accommodate a nearly unlimited range of foot shapes and sizes, however, a sufficient amount or a limited amount of slack must be provided. 
     Shoe laces present a simple engineering concept that does not always perform as planned. A shoe lace should be designed to slide easily through the eyelets or holes provided in the shoe or sneaker. This is necessary so that a proper setting of size and tension is achieved. However, once the lace is tied, it should stay tied. On close observation, it will be noted that these two requirements are diametrically opposed. Many laces, while easy to adjust, fail to stay tied, once knotted. To illustrate this problem, consider a newspaper account of a Marathon runner named John Kagwe: “Just one problem with the Nike Air Vengeance: the laces kept untying. ‘And I had triple knots,’ said Kagwe, of Kenya. Stopping twice to tie his shoes, and running the last four miles with the right lace flapping, Kagwe won the marathon in two hours, eight minutes, and twelve seconds through 26.2 miles in the rain . . . ” 
     Several inventors have addressed the problem of keeping laces adequately tied. In U.S. Pat. No. 5,272,796, issued to Nichols on Dec. 28, 1993 for SLIP RESISTANT SHOE LACE AND METHOD FOR MANUFACTURING SAME, a slip resistant shoe lace is illustrated. Strands of higher frictional coefficient are woven internally of the outer perimeter of the lace, in order to provide a frictionally enhanced lace that will not slip its knot. 
     In U.S. Pat. No. 4,780,936, issued to Brecher on Nov. 1, 1988 for STAY-TIED SHOE LACES, a shoe and lace combination is shown that impedes the loosening of a tied lace. The tongue of a shoe is provided with a flexible band member that folds over the lace after it has been knotted. The band secures the knot from unraveling. The flexible band is itself held in its fold-over position by means of a Velcro patch disposed thereupon, that mates with a corresponding patch on a distal end thereof. 
     In U.S. Pat. No. 5,673,546, issued to Abraham et al. on Oct. 7, 1997 for NON-SLIP SHOELACES, a slip resistant shoe lace is illustrated. The lace features a plurality of special slip resistant yarns that contains slubs. The slubs, when woven into a lace, provide a length of material that has protuberances disposed along the length of the lace. These protuberances are meant to provide frictional “bumps” at periodic intervals, which bumps will prevent a tied lace from unravelling its knot. 
     None of these lace systems, however, has addressed the concurrent problem of assuring that the laces easily slide through the eyelets or holes provided for them. Indeed, these laces will resist becoming untied once knotted, but they are now more likely to resist being threaded through the eyelets of a shoe or sneaker. Adding frictional means within the yarn solves the problem of unravelling, but exacerbates the problem of threading the lace through the eyelets of the shoe. As aforementioned, the two objectives compete with each other, and require opposite design criteria. 
     In present day laces, the yarn presents a compromise between the competing objectives. One is forced to choose between non-slippage and ease of threading. 
     The present invention is a shoe lace that is easily threaded, looped, and adjusted through the eyelets of a shoe, while at the same time is capable of forming a non-slip knot, when tied. 
     One embodiment of the inventive device is a flat shoe lace comprising an upper and lower surface made of different materials. The novel lace configuration performs a function similar to that of hook-on-one-side, pile-on-the-other-side fasteners. Unlike Velcro®, however, the surfaces are not designed for adhesion, but for high static friction between the upper and lower surfaces of the flat lace. When tying the flat shoe lace, both surfaces inevitably come in contact with each other. In this way, the laces resist inadvertent untying. Both the upper and lower surfaces have a low coefficient of both static and sliding friction with respect to the eyelets or holes. This enables the lace to be threaded through with minimal effort. 
     Alternative embodiments for obtaining high lace-to-lace friction and negligible lace-to-eyelet friction are described in detail hereinbelow. 
     While the various embodiments describe flat or rectangular shaped laces, the novel design approach would also be applicable to a lace with a round or oval cross-section. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, there is provided a shoe lace that is easy to thread through the eyelets of a shoe or sneaker, and also provides a knot that does not slip, when tied. In one embodiment, the shoe lace is flat and comprises an upper and lower surface with different frictional properties. The two surfaces of the lace that are in contact with the eyelet(s) are made of yarns, the yarns being designed to be smooth and substantially friction-free with respect to the eyelets. Thus, the threading of the lace becomes smooth and easy. On the other hand, the surfaces have a higher coefficient of friction with respect to one another. Moreover, any surfaces can be roughened by introducing slubs or “friction bumps” into the weave. 
     The surfaces of the lace present competing and opposite holding characteristics. During the tying process, such a lace tends to grab about the frictional surfaces, since these surfaces present the greater contacting surface area. Also, as the laces are looped during the tying process, they tend to skew and present the greater frictionalized surface area to the knot vortex. 
     It is an object of this invention to provide an improved lace for a shoe or sneaker. 
     It is another object of the invention to provide a shoe lace that is easy to thread through the eyelet of a shoe or sneaker, but the knot of which resists untying or slipping open. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A complete understanding of the present invention may be obtained by reference to the accompanying drawings, when considered in conjunction with the subsequent detailed description, in which: 
     FIG. 1 illustrates a partial, enlarged, perspective view of the shoe lace of this invention; 
     FIG. 2 depicts a partial, enlarged, perspective, in situ view of the shoe lace shown in FIG. 1, as it passes through the eyelet of a shoe; 
     FIG. 3 shows an enlarged, perspective view of the shoe lace shoe in FIG. 1, as it is tied into a knot; 
     FIG. 4 illustrates a partial, enlarged, perspective view of an alternative embodiment of the present invention; 
     FIG. 5 depicts a partial, enlarged, perspective, in situ view of he alternative embodiment of the lace shown in FIG. 4, as it passes through the eyelet of a shoe; 
     FIG. 6 shows an enlarged, perspective view of the alternative embodiment of the lace shown in FIG. 4, as it is tied into a knot; 
     FIG. 7 illustrates a perspective view of another alternative embodiment of this invention; 
     FIG. 8 illustrates a partial, enlarged, perspective view of another embodiment of the lace in accordance with the present invention; 
     FIG. 9 depicts a partial, enlarged, perspective, in situ view of the embodiment of the lace shown in FIG. 8, as it passes through the eyelet of a shoe; and 
     FIG. 10 shows an enlarged, perspective view of the embodiment of the lace shown in FIG. 8, as it is tied into a knot. 
    
    
     For purposes of brevity and clarity, like elements and components will bear the same number or designation throughout the figures. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Generally speaking, the invention features a flat lace, the opposing sides having a high coefficient of friction between them, while each side has a low coefficient of friction relative to the eyelets or holes through which the laces pass. This disparity in coefficients can be achieved by using a Velcro-like approach, with dissimilar configurations on the two sides of the lace. 
     Referring now to FIG. 1, the shoe lace  10  of this invention is illustrated in partial, enlarged, perspective view. The shoe lace  10  comprises a cylindrical, threading end cap  12  and a length of yarn  14  (shown herein cut short for viewing purposes). The length of yarn  14  is flat, as illustrated at the cut end  13 . The yarn  14 , itself, comprises an upper surface  16  and a lower surface  18  made of different materials bonded together either by mechanical fastening (e.g., sewing) or by an intumescent layer of adhesive, not shown. Alternatively, different materials may be affixed or sprayed to the upper and lower surfaces  16  and  18 , respectively. The surfaces  16  and  18  can be made with coarse or corded fibers to increase friction. Slubs or “friction bumps” may also be introduced into the weave of the respective surfaces  16  and  18  to increase the friction thereof. 
     The purpose of making surfaces  16  and  18  from different materials is to provide an interface  20  (FIG. 3) having a relatively high coefficient of friction. Thus, surfaces  16  and  18  will provide non-slippage during the knotting of the yarn  14 . However, the surfaces  16  and  18  both have a relatively low coefficient of friction when in contact with the inner eyelet surface  22  of a shoe, thereby allowing the lace  10  to be threaded easily, as further explained hereinbelow. 
     Referring now to FIG. 2, a portion of the yarn  14  of shoe lace  10  is shown passing (arrow  26 ) through one eyelet  24  of a plurality of typical eyelets for a shoe or sneaker (not shown). The yarn  14  easily passes through the eyelet  24  due to the reduced friction existing between the contacting surfaces  16  or  18  and eyelet surface  22 . 
     Referring to FIG. 3, the yarn  14  is shown being tied into a knot matrix  28 , in keeping with tying of the lace  10  about the front of a shoe or sneaker. For purposes of forming the knot matrix  28 , the upper and lower surfaces  16  and  18 , respectively, come into substantial contact with each other at points “A”, “B”, and “C”, as the knot matrix  28  is formed. Thus, the overall effect of the bifurcated frictional lace structure is to provide a knot matrix  28  that does not slip. 
     Referring now to FIG. 4, the shoe lace  30  of an alternative embodiment is illustrated in partial, enlarged, perspective view. The material used to make the lace  30  (i.e., yarn  34 ) is the same throughout the entire lace  30 . A rectangular lace is used in this embodiment. However, flat, rounded, elliptical, or other shaped laces can incorporate the design elements described hereinbelow. 
     The lace  30  comprises a brush-like array  36  of tiny fibers  38  protruding from the lace surface  42 . These fibers  38 , having a relatively low coefficient of friction (i.e., a coefficient between that of Teflon and nylon), slide easily through the eyelet  24 . At the same time, the lace  30  is resistant to sliding against itself; hence, knots in lace  30  remain tied. 
     The shoe lace  30  comprises a cylindrical, threading end cap  32  and a length of yarn  34  (shown herein cut short for viewing purposes). Again, slubs or “friction bumps” may be introduced into the weave to further increase the friction thereof. 
     The purpose of constructing the lace  30  with a brush-like array  36  of tiny fibers  38  is to provide increased surface area for contact. Fibers  38  come in contact with one another and with the lace surface  42 . Increasing the surface area increases the friction, thereby causing the lace  30  to remain tied. Furthermore, the fibers  38  can be made of a material with a relatively high coefficient of friction. 
     Referring to FIG. 5, a portion of the yarn  34  of shoe lace  30  is shown passing (arrow  46 ) through one eyelet  24  of a plurality of typical eyelets for a shoe or sneaker (not shown). The fibers  38  have a low coefficient of friction with respect to the inner eyelet surface  22 . It will be observed that the fibers  38  and, to a lesser extent, yarn  34  come into contact with the inner eyelet surface  22 . The lace  30  can easily pass through the eyelet  24 . 
     Referring to FIG. 6, the yarn  34  is shown being tied into a knot matrix  48 , in keeping with tying of the lace  30  about the front of a shoe or sneaker. For purposes of forming the knot matrix  48 , the fibers  38  come into substantial contact with each other. Also, lace surfaces  42  come in contact at points “D”, “E”, and “F”, as the knot matrix  48  is formed. 
     Referring now to FIG. 7, shown is the shoe lace  50  of another embodiment of the invention in a perspective view. Lace  50  has a middle portion  52  having material properties different from end portions  54 . Middle portion  52  is the part that, after the shoe is laced, is near or inside eyelet  24  (FIG. 5) and is made of material with a relatively low coefficient of friction. 
     End portions  54 , having a relatively high coefficient of friction, are involved in the knotting or tying. The difference in friction between middle and end portions  52  and  54 , respectively, is accomplished by using either different types of fibers (e.g., substantially frictionless material such as polytetrafluoroethylene (PTFE) for the middle of the laces, nylon for the end portions), different weaves, or both. 
     Now referring to FIG. 8, the shoe lace  60  of another embodiment of the invention is illustrated in partial, enlarged, perspective view. The shoe lace  60  comprises a cylindrical, threading end cap  62  and a length of yarn  64  (shown herein cut short for viewing purposes). The length of yarn  64  has a rectangular cross-section  66 , as illustrated at the cut end. The broader or wider paired sides  68  and  70 , respectively, of the lace  60  are made with coarse or corded fibers to increase its friction. Slub or “friction bumps” may also be introduced into the weave of the respective sides  68  and  70  to increase the friction thereof. 
     The smaller, adjacently paired sides  72  and  74  are made smooth and relatively friction-free. This can be accomplished by using substantially frictionless material such as polytetrafluoroethylene (PTFE) threads or by coating these surfaces with substantially frictionless material such as polytetrafluoroethylene (PTFE). 
     The purpose of making adjacently paired surfaces ( 68 ,  70 ) and ( 72 ,  74 ), respectively, of the rectangular shaped yarn  64  is to provide different coefficients of friction to these surfaces. Thus, when threading the lace  60 , the smooth surfaces  72  and  74  contact the eyelets of a shoe, allowing the lace  60  to be threaded easily. Alternately, the roughened sides  68  and  70  provide non-slippage during knotting of the yarn  64 . 
     Referring to FIG. 9, a portion of the yarn  64  of shoe lace  60  is shown passing (arrow  78 ) through one eyelet  76  of a plurality of typical eyelets for a shoe or sneaker (not shown). Only the smooth, teflonized sides  72  and  74 , respectively, come into contact with the inner eyelet surface  80 . The yarn  64  easily passes through the eyelet  76  due to the reduced friction existing between the contacting surfaces  72  and  80 , and surfaces  74  and  80 , respectively. During the threading of lace  60  through the eyelet  76 , the broader or wider sides  68  and  70 , respectively, rarely touch the inner surface  80  of eyelet  76 . 
     Referring to FIG. 10, the yarn  64  is shown being tied into a knot matrix  82 , in keeping with tying of the lace  60  about the front of a shoe or sneaker. For purposes of forming the knot matrix  82 , the upper and lower, wider frictional sides  68  and  70 , respectively, come into substantial contact with each other at points “G”, “H”, and “I”, as the knot matrix  82  is formed. The smoother, smaller sides  72  and  74  have minimal contact with each other and with the adjacent sides  68  and  70 , barely influencing the formation of the knot matrix  82 . Thus, the overall effect of the bifurcated frictional lace structure is to provide a knot matrix  82  that does not slip. 
     Although the lace of this invention has been described for footwear, it is conceivable that such a lace may also be usefully employed with other wearing apparel such as ski jackets, hoods, etc. Moreover, the lace can be flat, rectangular, polygonal, cylindrical, spherical, or asymmetrical, as befits its application(s). 
     Since other modifications and changes varied to fit particular operating requirements and environments will be apparent to those skilled in the art, the invention is not considered limited to the example chosen for purposes of disclosure, and covers all changes and modifications which do not constitute departures from the true spirit and scope of this invention. 
     Having thus described the invention, what is desired to be protected by Letters Patent is presented in the subsequently appended claims.