Active headrest assembly for vehicle

1. An active headrest assembly for a vehicle, comprising:

a headrest supported by a seat back frame including an upper cross member, a lower cross member, and side frame members connecting the upper cross member with the lower cross member at both ends thereof so as to form a space therein;

an active plate secured in the space and connected to the headrest and pivotally coupled to the upper cross member of the seat back frame so as to be moved in response to a predetermined force applied to the active plate and thereby move the headrest pivotally toward an occupant, wherein the active plate includes vertical guide slots defined therein;

guide pins slidably secured to the vertical guide slots of the active plate;

a lumbar unit including a support plate, a lumbar plate to cover the support plate, and a U-shaped support wire disposed below the lumbar plate and configured to slidably support the support plate, wherein distal ends of the U-shaped support wire includes the guide pins, a lower portion of the U-shaped support wire is hingedly connected to the lower cross member of the seat back frame, and the guide pins attached to the U-shaped support wire move the active plate in a rearward direction while the guide pins pulls the active plate in response to the predetermined force; and

returning units elastically connecting the side frame members to the active plate and configured to return the active plate by an elastic force of the returning units as the predetermined force applied to the active plate is released;

wherein the guide pin comprises a clip portion having a conical shape and seated against the guide slot, a head portion, to which an end of the support wire is secured, and a body portion connecting the clip portion and the head portion with each other and slides along the guide slot.

2. The active headrest assembly according to claim 1 , wherein the support plate comprises an upper plate, a lower plate separate from and located below the upper plate, and curved plates secured to a rear surface of the lumbar plate and connecting the upper plate and the lower plate with each other.

3. The active headrest assembly according to claim 1 , wherein the returning unit comprises a rotation bracket hingedly connecting an end of the active plate and the seat back frame with each other, and a spring elastically connecting the rotation bracket and the active plate with each other.

4. The active headrest assembly according to claim 1 , wherein the lumbar unit further comprises a first actuator connected to the support plate to raise and lower the support plate, and a second actuator connected to the support plate to bend the lumbar plate.

5. The active headrest assembly according to claim 1 , wherein, when an upper end of the lumbar unit is pushed rearward, the support wire presses the active plate, and the headrest projects forward to support an occupant's neck.