Hinge assembly with over-center latch

Claim 1

A hinge assembly comprising: (a) first and second generally cylindrically-shaped sleeves including cutouts near adjacent ends thereof; (b) first and second U-channels fixedly disposed within said first and said second sleeves, respectively, each U-channel comprising a curved base portion, two substantially straight leg portions, and a tab extending from each leg portion through the cutout in said first or said second sleeve in which said U-channel is disposed, the tabs of said first and said second U-channels being pivotally connected for thereby enabling relative pivotal movement between said first and said second sleeves; (c) a primary link and two secondary links, each of said primary and said secondary links having flat sides, a small thickness and an elongated length for fitting side-by-side between said leg portions of said second U-channel when said first and said second sleeves are in an unfolded configuration, said secondary links being disposed parallel to each other each having one end pivotally connected to said second U-channel and the other end pivotally connected to an end of said primary link, the other end of said primary link being pivotally connected to said first U-channel, said primary and said secondary links being sized and arranged for comprising an overcenter latch; and (d) a torsion spring mounted on said first U-channel, having an arm positioned against said primary link and having a plurality of windings extending between said leg portions of said first U-channel sufficient to provide the spring force necessary for, through the pivotal connections among said primary link, said secondary links and said second U-channel, urging said second sleeve to pivot into said unfolded configuration abutting end-to-end with said first sleeve and also urging said primary link into a position together with said secondary links between said leg portions of said second U-channel and at an angle to said secondary links sufficient to lock said sleeves in said unfolded configuration.