Seat unit and seat

A seat unit, comprising:

• a pair of mirror-symmetrically arranged mechanical extension devices that are linked, the mechanical extension device comprising a seat assembly for attaching a seat portion, a leg assembly adjustably assembled to a front end of the seat assembly, and a backrest assembly adjustably assembled to a rear end of the seat assembly, the seat assembly comprising a seat frame and a seat bracket that are slidable relative to each other in front-rear directions of the seat assembly, the seat bracket is fixed relative to ground, the leg assembly is pivotally connected to the seat frame, the backrest assembly is configured to be pivotally connected to both the seat frame and the seat bracket, and a pivot connection point between the backrest assembly and the seat frame is configured to move following the seat frame in response to the seat frame sliding relative to the seat bracket;
• a driving unit configured to drive the mechanical extension device so that the seat unit is switched sequentially among a sitting position, a TV position, and a lying position, with the seat frame sliding relative to the seat bracket;
• and
• a second damping member, wherein the second damping member is disposed between the leg assembly and the seat frame;
• the second damping member is configured to drive the leg assembly to extend toward a front of the seat assembly in response to the seat unit being switched from the sitting position to the lying position;
• the second damping member is configured to obstruct the leg assembly from retracting toward a rear of the seat assembly in response to the seat unit being switched from the lying position to the TV position.

A seat bracket, comprising a driving member and two mirror-symmetrically arranged and linked mechanical extension devices, wherein the mechanical extension device comprises:

• a seat assembly comprising a seat bracket and a seat frame, the seat frame being disposed on the seat bracket and slidable relative to the seat bracket;
• a leg assembly adjustably and pivotally connected to the seat frame;
• a backrest assembly configured to be pivotally connected to both the seat frame and the seat bracket, wherein a pivot connection point between the backrest assembly and the seat frame is configured to move following the seat frame in response to the seat frame sliding relative to the seat bracket, a highest point of the backrest assembly is configured to have a tendency to move in a horizontal direction following movement of the seat frame;
• the highest point of the backrest assembly is configured to have a tendency to move downward approaching the ground in a longitudinal direction in response to the seat frame sliding forward relative to the seat bracket;
• the highest point of the backrest assembly is configured to have a tendency to move upward moving away from the ground in the longitudinal direction in response to the seat frame sliding rearward relative to the seat bracket;
• the driving member comprises:
• a first driving unit disposed on the seat frame and configured to drive the leg assembly for position adjustment;
• a second driving unit disposed on the seat bracket and configured to drive the seat frame to slide relative to the seat bracket.