Footwear With Reactive Layers

Abstract

A fastening system for footwear that includes a strap that functions as a restraining element to more tightly secure the footwear to the wearer's foot when the strap is under tension. The strap could be a unitary strap made of a material with a negative Poisson's ratio. The strap can also have a composite structure, with an outer layer and an inner layer, where the inner layer is made of a material with a negative Poisson's ratio. As the strap is placed under tension in a lengthwise direction, the thickness and/or width of the strap may expand to increase support.

What is claimed is: 
     
         1 . An article of footwear comprising:
 an upper having a medial side and a lateral side;   a sole having a medial side and a lateral side; and   a strap attached at a medial end to at least one of the medial side of the upper and the medial side of the sole, and at a lateral end to at least one of the lateral side of the upper and the lateral side of the sole;   wherein the strap comprises a reactive material that increases in at least one of thickness and width when the strap is under longitudinal tension.   
     
     
         2 . The article of footwear of  claim 1 , wherein the strap is a composite strap having one inelastic layer at the outward side of the strap and one reactive layer at the inward side of the strap. 
     
     
         3 . The article of footwear of  claim 2 , wherein the reactive layer is permanently attached to the inelastic layer at each end of the strap. 
     
     
         4 . The article of footwear of  claim 2 , wherein the strap is routed over the arch of the footwear. 
     
     
         5 . The article of footwear of  claim 1 , wherein the strap is a unitary strap comprised of reactive material. 
     
     
         6 . The article of footwear of  claim 5 , wherein the strap is configured to be routed within the footwear over the arch of a wearer's foot. 
     
     
         7 . The article of footwear of claim of  claim 5 , wherein the strap is configured to be routed over the tongue of the footwear. 
     
     
         8 . The article of footwear of  claim 1 , wherein the strap is a heel strap. 
     
     
         9 . The article of footwear of  claim 1 , wherein the strap is a forefoot strap. 
     
     
         10 . The article of footwear of  claim 1 , wherein the footwear is one of a shoe, a boot, a slipper, a flipper, a sandal and a skate. 
     
     
         11 . An article of footwear comprising:
 an upper having a medial side and a lateral side;   a sole having a medial side and a lateral side; and   a unitary strap attached at a medial end to at least one of the medial side of the upper and the medial side of the sole, and at a lateral end to at least one of the lateral side of the upper and the lateral side of the sole;   wherein the unitary strap comprises a layer of reactive material; and   wherein the layer of reactive material increases in at least one of thickness and width when the strap is under longitudinal tension.   
     
     
         12 . The article of footwear of  claim 11 , wherein the unitary strap is routed wholly within the upper. 
     
     
         13 . The article of footwear of  claim 11 , wherein the upper comprises a slot on the lateral side of the upper, and wherein the unitary strap is attached to the interior of the medial side of the footwear, is routed up the medial side of the footwear and across to the lateral side, down the lateral side to a slot, is routed through the slot and is detachably attached to the exterior of the upper. 
     
     
         14 . An article of footwear comprising:
 a composite strap having an inner layer formed from reactive material and an outer layer formed from inelastic material such that when the composite strap is under longitudinal tension the reactive material increases in at least one of thickness and width.   
     
     
         15 . The article of footwear of  claim 14 , wherein the footwear is one of a slipper and a sandal, and the composite strap is one of a heel strap, an arch strap and a forefoot strap. 
     
     
         16 . The article of footwear of  claim 14 , wherein the footwear is a flipper and the composite strap is a heel strap. 
     
     
         17 . An article of footwear comprising:
 an upper having a medial side and a lateral side;   a sole having a medial side and a lateral side; and   a composite strap attached at a medial end to at least one of the medial side of the upper and the medial side of the sole, and at a lateral end to at least one of the lateral side of the upper and the lateral side of the sole;   wherein the composite strap comprises at least one layer of inelastic material and at least one layer of reactive material; and   wherein the at least one layer of reactive material increases in at least one of thickness and width when the strap is under longitudinal tension.   
     
     
         18 . The article of footwear of  claim 11 , wherein the composite strap is attached to the lateral side of the upper by a detachable device. 
     
     
         19 . The article of footwear of  claim 11 , further comprising a unitary reactive strap that is permanently attached at the medial side and at the lateral side to the interior of the footwear. 
     
     
         20 . The article of footwear of  claim 11 , wherein the layer of reactive material comprises an auxetic material. 
     
     
         21 . An article of footwear comprising:
 an upper having a medial side and a lateral side;   the upper further including a forward portion associated with a forefoot portion of the upper, a rearward portion associated with a heel portion of the upper and an intermediate portion disposed between the forward portion and the rearward portion; and   wherein the intermediate portion comprises a reactive material that increases in at least one of thickness and width when the intermediate portion is under longitudinal tension.   
     
     
         22 . The article of footwear according to  claim 21 , wherein the intermediate portion extends from the medial side of the upper to the lateral side of the upper. 
     
     
         23 . The article of footwear according to  claim 21 , wherein the intermediate portion extends from either side of a throat opening of the upper towards a sole of the article of footwear.