Active material actuated headrest utilizing bar linkage deployment system

An active headrest adapted for use with a seat, and to selectively support the head of an occupant, said headrest comprising:

• an exterior shell defining an interior space and outer surface configured to engage the head of the occupant;
• and
• an actuator disposed within the space, and operable to adjust the distance or engagement between the surface and head, wherein the actuator includes a bar linkage system presenting at least one selectively deployable swing arm pivotally coupled to the seat and shell,
• said actuator further including a shape memory alloy wire drivenly coupled to the arm, so as to cause or enable the arm to pivot, when the element is exposed to or occluded from an activation signal, a selectively engaged ratchet and pawl cooperatively configured to allow the headrest to translate in a first direction and prevent translation in the opposite direction when engaged, and a latch operable to selectively engage, so as to retain the shell in one of a plurality of achievable deployed positions, the element is configured to cause the latch to disengage when exposed to or occluded from the signal, and the actuator is configured to cause the arm to pivot only when the latch is disengaged.