Patent ID: 6880887

Claim:
A seat reclining device comprising: a lower arm fixed to a cushion of the seat; an upper arm rotatably engaging with the lower arm; a locking mechanism disposed between the lower arm and the upper arm and including a cam rotatable relative to either the lower arm or the upper arm and restricting a relative rotation between the lower arm and the upper arm by a rotation of the cam; and a spring disposed between the cam and one of the lower arm and the upper arm for biasing the cam in a direction in which the locking mechanism restricts the relative rotation between the lower arm and the upper arm, the spring wound around a rotational axis of the cam and disposed in a through hole formed on said one of the lower arm and the upper arm, the spring including an inner engaging portion to be engaged with the cam and an outer engaging portion to be engaged with the through hole, the through hole opening to opposite surfaces of said one of the lower arm and the upper arm; said spring possessing a thickness that is the same as a depth of the through hole as measured between said opposite surfaces.