Patent ID: 7556054

Claim:
A frame element, comprising: a first scissor comprising a first and a second strut pivotably connected to each other at a first pivot point; a second scissor comprising a third and a fourth strut pivotably connected to each other at a second pivot point; and a hub to which the first and the third strut are pivotably connected, the first and second scissors being pivotable about the hub between a closed position in which the first, second, third, and fourth struts are in a first substantially parallel relationship to one another and side-by-side, through an intermediate position in which the first and the third struts define a non-zero angle with each other and in which the second and fourth struts are substantially end-to-end and in a second substantially parallel relationship to each other and end-to-end, and to an open, locked position in which the first and third struts define the non-zero angle with each other, and the second and fourth struts define a second non-zero angle with each other and abutment portions of the second and fourth struts contact receiving portions of the third and first struts, respectively, and prevent the first and third struts from pivoting beyond the non-zero angle.