Patent ID: 7293829

Claim:
A headrest of a motor vehicle seat with a first structural component comprising fastening means for fastening said headrest to a seat back of said motor vehicle seat, with a second structural component that is disposed so as to be movable with respect to said first structural component, that comprises a bolster and that is moved forward with respect to said first structural component in an event of a crash, and with a drive unit that is disposed between said first structural component and said second structural component, that comprises a locking unit which is locked in a normal case and that has a crash sensor connected to said locking unit which it controls, wherein the locking unit comprises a disengagement drive with an electromagnet or a piezoelectric drive, that the locking unit comprises one retainer member associated with said first structural component and one movable disengagement member associated with said second structural component, that the retainer member and the disengagement member are connected together via a hinge or via balls, and that the disengagement drive is allocated to the movable disengagement member and is capable of causing said disengagement member to move, wherein the disengagement member comprises a circumferential groove, that said groove mates with said balls, that in the normal case the balls engage said groove and that the retainer member comprises an inner contour that the balls fit against and that said inner contour comprises outwardly extending bight portions that are at least as deep as the depth at which the balls engage the groove and each ball being assigned one bight portion.