Seat assembly having a thoracic support mechanism

1. A seat assembly comprising:

a seat back that has a seat back frame that includes:

upper and lower cross members that extend from a first side member to a second side member;

a cross bar that is disposed between the upper and lower cross members and extends from the first side member to the second side member; and

a support member that extends from the upper cross member to the cross bar; and

a thoracic support mechanism that is moveably disposed on the support member, the thoracic support mechanism including:

a flex plate that is moveably disposed on the support member, the flex plate having an upper end wall and a lower end wall disposed opposite the upper end wall;

a mounting plate that is disposed on the flex plate;

a first actuator that is operatively connected to the flex plate that actuates the lower end wall toward the upper end wall to flex the flex plate away from the cross bar; and

a second actuator that is operatively coupled to the mounting plate and that actuates the mounting plate and the flex plate along the support member.

2. The seat assembly of claim 1 wherein the second actuator and the first actuator adjust a position of the thoracic support mechanism to support at least a portion of a thoracic region of a user's spine.

3. The seat assembly of claim 1 wherein the thoracic support mechanism does not support a lumbar region of a user's spine.

4. The seat assembly of claim 1 wherein the upper end wall is disposed between the upper cross member and the cross bar and receives the support member such that the flex plate is slidable along the support member.

5. The seat assembly of claim 4 wherein the thoracic support mechanism further comprises a pivot member that is pivotally disposed on the mounting plate between the upper cross member and the cross bar, wherein the first actuator is coupled to the pivot member and rotates the pivot member with respect to the mounting plate when the lower end wall moves toward the upper end wall.

6. The seat assembly of claim 5 further comprising a biasing member that is coupled to the pivot member and the lower end wall, wherein the biasing member urges the lower end wall away from the upper end wall.

7. The seat assembly of claim 6 wherein the mounting plate is fixedly disposed on the upper end wall of the flex plate.

8. The seat assembly of claim 7 wherein the mounting plate is disposed between the flex plate and the cross bar and is spaced apart from the lower end wall of the flex plate.

9. The seat assembly of claim 8 wherein the lower end wall of the flex plate slides along the support member toward the mounting plate when the first actuator flexes the flex plate away from the cross bar and the lower end wall of the flex plate slides along the support member toward the lower cross member when the biasing member rotates the pivot member.