Backpack including suspension strap

Abstract

A strap system designed to cushion applied tensile force is disclosed. The strap system includes an expandable member configured to deform under the applied tension force and a restriction member that influences the deformation pattern of the expandable member. For example, the restriction member may limit the amount of stretch experienced by the expandable member. The strap system may be incorporated as shoulder straps into a backpack to reduce pressure to the back and shoulders typically experienced by a wearer.

What is claimed: 
     
         1 . A backpack comprising:
 an enclosure for storing items; and   a shoulder strap system coupled to the enclosure, the shoulder strap system comprising:
 an expandable member defining a longitudinal axis and a transverse axis, the expandable member comprising a resilient textile including a plurality of folds generally aligned on the transverse axis; and 
 a restriction member configured to limit expansion of the expandable member, the restriction member comprising a textile element coupled to the expandable member, the textile element extending from a first anchor to a second anchor. 
   
     
     
         2 . The backpack according  claim 1 ,
 the textile element is secured to the expandable member by the first anchor and the second anchor; and   the textile element is unsecured in an area between the first anchor and the second anchor.   
     
     
         3 . The backpack according to  claim 2 , wherein the plurality of folds includes a generally concave fold and a generally convex fold. 
     
     
         4 . The backpack according to  claim 3 , wherein:
 the expandable member expands when a tensile force is applied in a longitudinal direction; and   the textile element of the restriction member is capable of transitioning from a generally convex configuration to a generally planar configuration during expansion of the expandable member.   
     
     
         5 . The backpack according to  claim 1 , wherein the restriction member comprises a plurality of textile elements generally aligned with the longitudinal axis of the expandable member. 
     
     
         6 . The backpack of  claim 1 , wherein the expandable member resists contraction along the transverse axis as tension is applied along the longitudinal axis. 
     
     
         7 . The backpack of  claim 1 , wherein the folds of the expandable member are organized in a repeating pattern effective to lower a Poisson's ratio of the expandable member. 
     
     
         8 . The backpack of  claim 1 , wherein the folds of the expandable member are organized in a repeating pattern effective to generate a negative Poisson's ratio for the expandable member. 
     
     
         9 . The backpack according to  claim 1 , wherein:
 the resilient textile of the expandable member comprises a woven textile including more than 5% elastic strands based on total number of strands that form the resilient textile; and   the textile element of the restriction member comprises a woven textile including less than 5% elastic strands based on a total number of strands that form the textile element.   
     
     
         10 . The backpack according to  claim 1 , wherein:
 the expandable member is biased toward a normal, contracted position by elastic strands within the resilient textile of the expandable member;   the expandable member is capable of expanding from the normal, contracted position to a fully expanded position by increasing a distance between adjacent folds;   the restriction member extends longitudinally along the expandable member such that the restriction member spans the plurality of folds; and   the restriction member prevents expansion of the expandable member to the fully expanded position.   
     
     
         11 . A shoulder strap system comprising:
 an expandable member defining a longitudinal axis and a transverse axis, the expandable member comprising a resilient textile including a plurality of folds oriented on the transverse axis; and   a restriction member configured to limit expansion of the expandable member, the restriction member comprising a textile element coupled to the expandable member, the textile element extending from a first anchor to a second anchor.   
     
     
         12 . The shoulder strap system according  claim 11 ,
 the textile element is secured to the expandable member by the first anchor and the second anchor; and   the textile element is unsecured in an area between the first anchor and the second anchor.   
     
     
         13 . The shoulder strap system according to  claim 12 , wherein the expandable member comprises a first, generally concave fold and a second, general convex fold. 
     
     
         14 . The shoulder strap system according to  claim 13 , wherein:
 the expandable member expands when a tensile force is applied along the longitudinal axis of the expandable member; and   during expansion of the expandable member, the textile element is capable of transitioning from a generally convex configuration to a generally planar configuration.   
     
     
         15 . The shoulder strap system according to  claim 11 , wherein the restriction member comprises an array of textile elements generally aligned with the longitudinal axis of the expandable member. 
     
     
         16 . The shoulder strap system of  claim 11 , wherein the expandable member resists contraction along the transverse axis as tension is applied along the longitudinal axis. 
     
     
         17 . The shoulder strap system of  claim 11 , wherein the folds are organized in a repeating pattern effective to lower a Poisson's ratio of the expandable member. 
     
     
         18 . The shoulder strap system of  claim 11 , wherein the folds are organized in a repeating pattern effective to generate a negative Poisson's ratio for the expandable member. 
     
     
         19 . The shoulder strap system according to  claim 11 , wherein:
 the resilient textile of the expandable member comprises a woven textile including more than 5% elastic strands based on total number of strands that form the resilient textile; and   the textile element of the restriction member comprises a woven textile including less than 5% elastic strands based on a total number of strands that form the textile element.   
     
     
         20 . The shoulder strap system according to  claim 11 , wherein:
 the expandable member is biased toward a normal, contracted position elastic strands within the resilient textile of the expandable member;   the expandable member is capable of expanding from the normal, contracted position to a fully expanded position by increasing a distance between adjacent folds;   the restriction member extends longitudinally along the expandable member such that the restriction member spans the plurality of folds; and   the restriction member prevents expansion of the expandable member to the fully expanded position.