Patent Publication Number: US-8966786-B2

Title: Flip-flop

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to footwear, more particularly to a flip-flop. 
     2. Description of the Related Art 
       FIG. 1  shows a conventional flip-flop including a sole  11  and a strap unit  12 . The strap unit  12  includes two woven straps  121  each of which has a first end portion  1210  that is secured to a left or right side of a middle part of the sole  11 , and a second end portion  1211  that is stitched to the second end portion  1211  of the other one of the woven straps  121  to form a stitched thong  122 . The stitched thong  122  is secured to a front part of the sole  11  and is disposed to fit between the first and second toes of a wearer&#39;s foot. 
     The strap unit  12  is made by two independent processes, i.e., separately weaving the two woven straps  121 , and stitching the woven straps  121  to form the stitched thong  122 . Thus, the strap unit  12  of the conventional flip-flop is produced with a relatively low efficiency and at a relatively high cost. 
     Although the strap unit  12  can be formed by a single process using a plastic material, it may give the wearer an unpleasant tactile feeling and may have a weaker stretch strength compared with the strap unit  12  made by weaving/stitching processes. 
     SUMMARY OF THE INVENTION 
     Therefore, an object of the present invention is to provide a flip-flop that can be made in a single continuous process using a weaving method, especially a double weft needles method. 
     According to this invention, a flip-flop includes a sole for a wearer&#39;s foot to rest thereon, and a strap unit. The sole has upper and lower surfaces, and the upper surface includes front, middle and rear regions. The strap unit includes a thong portion which has a first thong end secured to the front region, and a second thong end opposite to the first thong end, and first and second strap portions extending rearwardly from the second thong end to terminate at and be secured to left and right sides of the middle region, respectively. The strap unit is made by the steps of: 
     (a) providing superposed first and second layers of warp threads; 
     (b) inserting a first weft thread through sheds formed in the first layer of warp threads so as to weave the first strap portion along a first lengthwise line such that one of first leading and trailing ends of the first strap portion has a first oblique boundary which is at an oblique angle to the first lengthwise line; 
     (c) inserting a second weft thread through sheds formed in the second layer of warp threads so as to weave the second strap portion along a second lengthwise line such that one of second leading and trailing ends of the second strap portion has a second oblique boundary which is at an oblique angle to the second lengthwise line, and which joins the first oblique boundary to cooperatively define the second thong end at which the first and second lengthwise lines meet; and 
     (d) inserting the first and second weft threads through sheds which are cooperatively formed by the superposed first and second layers of warp threads so as to weave the thong portion along a direction from one of the first and second thong ends to the other one of the first and second thong ends. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiments of the invention, with reference to the accompanying drawings, in which: 
         FIG. 1  is a schematic view of a conventional flip-flop; 
         FIG. 2  is a schematic view of a strap unit used in a first preferred embodiment of a flip-flop according to this invention; 
         FIG. 3  is a side view of the strap unit shown in  FIG. 2 , showing that a first strap portion and a first extension portion are respectively stacked on a second strap portion and a second extension portion; 
         FIG. 4  is a schematic view of the first preferred embodiment of the flip-flop according to this invention; 
         FIGS. 5 and 6  are fragmentary views illustrating the process for weaving the strap unit of this invention; and 
         FIG. 7  is a schematic view of a strap unit used in a second preferred embodiment of a flip-flop according to this invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Before the present invention is described in greater detail, it should be noted herein that like elements are denoted by the same reference numerals throughout the disclosure. 
     Referring to  FIGS. 2 to 4 , a first preferred embodiment of a flip-flop according to this invention is shown to include a strap unit  2  and a sole  3  for a wearer&#39;s foot to rest thereon. The sole  3  has upper and lower surfaces  301 ,  302 . The upper surface  301  includes front, middle and rear regions  31 ,  32 ,  33 . 
     The strap unit  2  includes first and second extension portions  21 ,  22 , a thong portion  23 , and first and second strap portions  24 ,  25 . The thong portion  23  has a first thong end  231  secured to the front region  31 , and a second thong end  232  opposite to the first thong end  231  in a lengthwise direction of the strap unit  2 . The first strap portion  24  extends rearwardly from the second thong end  232  through the sole  3  at a left side of the middle region  32  to terminate at a distal end  241  which is secured to the lower surface  302  of the sole  3 . The second strap portion  25  extends rearwardly from the second thong end  232  through the sole  3  at a right side of the middle region  32  to terminate at a distal end  251  which is secured to the lower surface  302  of the sole  3 . The first and second extension portions  21 ,  22  extend downwardly from the first thong end  231  through the sole  3  at the front region  31  and are secured to the lower surface  302  of the sole  3 . A first lengthwise line  242  of the first strap portion  24  and a second lengthwise line  252  of the second strap portion  25  cooperatively define an included angle θ that ranges between 30° and 90°. 
     With reference to  FIGS. 5 and 6 , the strap unit  2  shown in  FIGS. 2 and 3  is made by a double weft needles method using a needle loom  6  which is preferably a computerized jacquard loom. Steps (a) to (f) are implemented for continuously weaving a plurality of the strap units  2 . It should be noted that the sequence of steps (a) to (f) is limited to that disclosed herein or shown in  FIG. 5 , and may vary depending on the weaving direction of the strap units  2 . That is, although in the embodiment shown in  FIG. 5 , each strap unit  2  is woven by weaving, in order, the first and second extension portions  21 ,  22 , the thong portion  23 , and the first and second strap portions  24 ,  25 , it may be woven in an opposite order. 
     In step (a), superposed first and second layers of warp threads  61 ,  62 , which can be made by any known method, are arranged in the needle loom  6 . 
     Instep (b), a first weft thread  63  is inserted through sheds formed in the first layer of warp threads  61  using a first weft needle  65  so as to weave the first strap portion  24  along the first lengthwise line  242  from a first leading end  243  to a first trailing end  244  such that one of the first leading and trailing ends  243 ,  244  has a first oblique boundary  245  which is at an oblique angle to the first lengthwise line  242 . In this embodiment, the first leading end  243  has the first oblique boundary  245 . 
     In step (c), a second weft thread  64  is inserted through sheds formed in the second layer of warp threads  62  using a second weft needle  66  so as to weave the second strap portion  25  along the second lengthwise line  252  from a second leading end  253  to a second trailing end  254  such that one of the second leading and trailing ends  253 ,  254  has a second oblique boundary  255  which is at an oblique angle to the second lengthwise line  252 , and which joins the first oblique boundary  245  to cooperatively define the second thong end  232  at which the first and second lengthwise lines  242 ,  252  meet. In this embodiment, the second leading end  253  has the second oblique boundary  255 . Steps (b) and (c) are simultaneously implemented for weaving both the first and second strap portions  24 ,  25 . 
     In step (d), the first and second weft threads  63 ,  64  which are respectively guided by the first and second weft needles  65 ,  66  are inserted through sheds which are cooperatively formed by the superposed first and second layers of warp threads  61 ,  62  so as to weave the thong portion  23  along a direction from one of the first and second thong ends  231 ,  232  to the other one of the first and second thong ends  231 ,  232 . In this embodiment, the thong portion  23  is woven along the direction from the first thong end  231  to the second thong end  232 . 
     In step (e), the first weft thread  63  is inserted through sheds formed in the first layer of warp threads  61  by the first weft needle  65  so as to weave the first extension portion  21  from the first thong end  231  or the first trailing end  244  of the first strap portion  24  of a preceding one of the strap units  2 . In this embodiment, the first extension portion  21  is woven from the first trailing end  244  of the first strap portion  24  of the preceding one of the strap units  2 . (see  FIG. 5 ). 
     In step (f), the second weft thread  64  is inserted through sheds formed in the second layer of warp threads  62  by the second weft needle  66  so as to weave the second extension portion  22  from the first thong end  231  or the second trailing end  254  of the second strap portion  25  of a preceding one of the strap units  2 . In this embodiment, the second extension portion  22  is woven from the second trailing end  254  of the second strap portion  25  of the preceding one of the strap units  2  (see  FIG. 5 ). 
     The plurality of the strap units  2  can be successively and efficiently produced using the needle loom  6 , and the patterns and the shapes of the strip unit  2  can be varied according to design requirement. For example, as shown in  FIG. 3 , each of the first and second strap portions  24 ,  25  may have an increased width section/segment that gradually increases in width away from the second thong end  232 , and an equal-width section/segment extending from increased width section/segment toward the respective distal end  241  ( 251 ). 
     In this embodiment, each of the warp threads  61 ,  62  and the first and second weft threads  63 ,  64  is selected from a terylene yarn (which may be a high-tension yarn or a low-tension yarn), a nylon yarn (which may be a high-tension yarn or a low-tension yarn), a metallic yarn, etc. 
       FIG. 7  shows a strap unit  2  used in a second preferred embodiment of a flip-flop according to this invention. In this embodiment, the strap unit  2  further includes two reinforcing pieces  26  disposed on the first and second strap portions  24 ,  25 , respectively, and extending along the first and second lengthwise lines  242 ,  252 , respectively. With the provision of the reinforcing pieces  26 , the structure of the first and second strap portions  24 ,  25  can be enhanced. 
     While the present invention has been described in connection with what are considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretations and equivalent arrangements.