Fields of values and inclusion regions for matrix pencils

A hinge assembly includes a body adapted for connection to a first structure. A resilient member is in contact with the body, and a cam is pivotally movable relative to the body and adapted for connection to a second structure. An actuating member is positioned between the resilient member and the cam and biased by the resilient member into contact with the cam so that the actuating member exerts a force on said cam. The body defines a cylindrical bore and the resilient member is provided by a coil spring positioned in the bore. The actuating member is provided by a spherical ball member and the cam defines a lobe portion and a recessed dwell region. The cam is adapted for movement between first and second operative positions. When in the first operative position, the lobe portion of the cam is engaged with the actuating member. The lobe portion is defined so that, when the cam is in its first operative position, the actuating member urges the cam toward its second operative position. When the cam is moved to its second operative position, the actuating member and the recessed cam portion provide a detent mechanism that holds the cam in the second operative position.