Patent ID: 7108320

Claim:
A head restraint for a vehicle seat, wherein the head restraint operates favorably in response to an event of predetermined magnitude, and the head restraint comprises: a first subassembly; a second subassembly mounted for moving forward relative to the first subassembly; a drive mounted for moving the second subassembly forward relative to the first subassembly; and a locking unit operative for having (a) a locked state prior to the event of predetermined magnitude, wherein in the locked state the locking unit prevents the drive from moving the second subassembly forward relative to the first subassembly, and (b) an unlocked state in response to the event of predetermined magnitude, wherein in the unlocked state the locking unit does not prevent the drive from moving the second subassembly forward relative to the first subassembly, whereby the drive moves the second subassembly forward relative to the first subassembly in response to the event of predetermined magnitude, wherein the locking unit comprises a magnet arranged so that a magnetic field of the magnet is operative for maintaining the locking unit in the locked state prior to the event of predetermined magnitude, and wherein the magnet is a permanent magnet and the locking unit further comprises a coil that is for producing a magnetic field in response to the coil being electrically energized.