Bistable pivot hinge

Abstract

Embodiments described herein take the form of a bistable hinge. The bistable hinge typically includes an elastic element and a pair of rigid structures. Each rigid structure in the illustrated embodiment includes a pair of pivot cylinders connected to a rotating surface, as well as a detent formed on a portion of the rotating surface. The elastic element is retained by the detent, such that the spring force of the elastic element, when stretched, is transmitted to the rigid structure. The rigid structure may incorporate any suitable protrusions, retainers, or the like around which the elastic element extends in lieu of the illustrated detents. As the elastic element is stretched during operation of the hinge, the elastic element maintains contact with the detents. Further, as the hinge transitions from a closed state to an open state, the detents stretch the elastic element, thereby applying tension to it.

What is claimed is: 
     
         1 . A bistable hinge, comprising:
 an elastic element;   a first rotating surface attached to the elastic element;   a second rotating surface attached to the elastic element;   a first detent attaching the first rotating surface to the elastic element; and   a second detent attaching the first rotating surface to the elastic element; wherein:
 the elastic element biases the first and second rotating surfaces to a first position when the elastic element is on a first side of a pivot plane; and 
 the elastic element biases the first and second rotating surfaces to a second position when the elastic element is on a second side of the pivot plane. 
   
     
     
         2 . The bistable hinge of  claim 1 , wherein the pivot plane includes a pivot axis about which the first and second rotating surfaces rotate. 
     
     
         3 . The bistable hinge of  claim 1 , wherein:
 an internal tension of the elastic element increases as the bistable hinge opens; and   the internal tension of the elastic element decreases as the bistable hinge closes.   
     
     
         4 . The bistable hinge of  claim 1 , wherein:
 the first and second rotating surfaces move rotationally about a pivot axis within the pivot plane; and   the first and second rotating surfaces are constrained from moving laterally with respect to one another.   
     
     
         5 . The bistable hinge of  claim 4 , further comprising at least one securement strip affixed to the first rotating surface and the second rotating surface, wherein the at least one securement strip permits rotational movement of the first and second rotating surfaces but constrains the first and second rotating surfaces from moving laterally with respect to one another. 
     
     
         6 . The bistable hinge of  claim 1 , wherein the elastic element is in an unstable equilibrium with respect to the pivot axis when the first and second rotating elements are within or parallel to the pivot plane. 
     
     
         7 . A pivot structure, comprising:
 a first pivot cylinder;   a second pivot cylinder abutting the first pivot cylinder;   a first securement strip passing between the first and second pivot cylinders and attached to the first pivot cylinder; and   a second securement strip passing between the first and second pivot cylinders and attached to the second pivot cylinder; wherein:   the first and second pivot cylinders revolve about a pivot axis defined along abutting surfaces of the first and second pivot cylinders.   
     
     
         8 . The pivot structure of  claim 7 , wherein:
 the first securement strip is further attached to the second pivot cylinder; and   the second securement strip is further attached to the first pivot cylinder.   
     
     
         9 . The pivot structure of  claim 7 , wherein:
 the first and second securement strips permit the first and second pivot cylinders to revolve about the pivot axis; and   the first and second securement strips prevent lateral motion of the first and second pivot cylinders with respect to one another.   
     
     
         10 . The pivot structure of  claim 7 , further comprising:
 a third pivot cylinder attached to the first pivot cylinder by a first rotating surface; and   a fourth pivot cylinder attached to the second pivot cylinder by a second rotating surface; wherein:   the third and fourth pivot cylinders revolve about the pivot axis; and   the pivot axis intersects abutting surfaces of the third and fourth pivot cylinders.   
     
     
         11 . The pivot structure of  claim 10 , wherein:
 the first securement strip is further attached to the third cylinder;   the second securement strip is further attached to the fourth cylinder;   the first securement strip passes through the pivot axis; and   the second securement strip passes through the pivot axis.   
     
     
         12 . The pivot structure of  claim 11 , wherein:
 the first securement strip defines a first cutout;   the second securement strip defines a second cutout; and   the first and second cutouts permit the first and second securement strips to pass through the pivot axis without overlapping one another laterally.   
     
     
         13 . The pivot structure of  claim 12 , wherein the securement strips permit the pivot cylinders to revolve 180 degrees about the pivot axis. 
     
     
         14 . The pivot structure of  claim 11 , further comprising:
 a first rotating structure attached to the first pivot cylinder, second pivot cylinder, first securement strip, and second securement strip; and   a second rotating structure attached to the third pivot cylinder, fourth pivot cylinder, first securement strip, and second securement strip; wherein:   the first and second securement strips permit the first and second rotating structures to rotate about the pivot axis but inhibit lateral motion of the first and second rotating structures with respect to one another.