Abstract: A seatback includes a pressure-receiving member and a drive mechanism. The pressure-receiving member includes a first pressure-receiving portion configured to support a lumbar region of an occupant, and a second pressure-receiving portion joined to an upper part of the first pressure-receiving portion and configured to support a back of the occupant in cooperation with the first pressure-receiving portion. The drive mechanism is configured to displace the pressure-receiving member between a support position and a non-support position, which is a position rearward of the support position. The pressure-receiving member is configured, when in the support position, to be bent at a joining portion where the first pressure-receiving portion and the second pressure-receiving portion are joined together to become convex toward a seat front side.

Abstract: A pivot shaft assembly for a foldable device includes a base seat, a shaft member and a locking member. The base seat has a through hole and an engaging portion. The shaft member extends through the through hole, includes a fixed tubular piece with a radial hole, and is rotatable relative to the base seat. The locking member includes a locking portion movably disposed in the radial hole. The locking portion is movable through the radial hole to engage with the engaging portion to position the pivot shaft assembly in a locked state so as to prevent rotation of the shaft member relative to the base seat, and is movable inwardly of the fixed tubular piece to disengage from the engaging portion to make the pivot shaft assembly in a released state so as to permit rotation of the shaft member relative to the base seat.