US Patent 7377582 Supporting structure and seat apparatus having a retractable seat

A seat apparatus include: a shaft rotated by a motor and operatively associated with the seat so as to move the seat; a first leg secured to the shaft and pivotably supported by the seat; a first spring, one end of which is fixedly attached to the shaft and an other end of which is fixedly attached to the seat; the first spring which biases the shift in a first direction; and a second spring, one end of which is fixedly attached to the shaft and an other end of which is fixedly attached to the seat, the second spring which biases the shaft in a second direction. The first direction opposes to the second direction.