Patent ID: 7192083

Claim:
A linkage mechanism including four pivoting bars, having an open position in which the first bar forms one side of a substantially triangular shape, the second and third bars are generally collinear to form a second side of the triangular shape, and the fourth bar forms a third side of the triangular shape, and a closed position in which the first bar, second bar, third bar and fourth bar are substantially aligned, the first bar being pivotally joined to the second bar, the second bar being pivotally joined to the third bar, the third bar being pivotally joined to the fourth bar, and the fourth bar being pivotally linked to the first bar by a pivot which moves along a curved path such that no point on the first bar remains coincident with any point on the fourth bar during relative movement of said first and fourth bars, a fifth bar being pivotally attached to the first bar.