Patent attributes
A seat reclining mechanism comprises a plurality of lock gear members. One of the plurality of lock gear members has a protrusion which protrudes toward an internal gear member. The internal gear member has a first free-zone arc portion formed along a circle having a center on a rotation axis and adapted to allow the protrusion to be in contact therewith when the lock gear members are located at a position where external teeth of each of lock gear members are not in meshing engagement with internal teeth of the internal gear, and a second free-zone arc portion formed along the circle to have an arc length different from that of the first free-zone arc portion and adapted to allow the protrusion to be in contact therewith when the lock gear members are located at the position.
