Patent ID: 8130123

Claim:
A rotary actuator comprising: a roller having a center axis, the roller having a first center shaft protruding along the center axis; a first bearing surrounding the first center shaft for supporting the first center shaft of the roller to allow the roller to rotate about the center axis; a first ring magnet fixed to the first center shaft of the roller, the first ring magnet being alternately magnetized to an S-pole and an N-pole with predetermined angular intervals; a first elastic member provided between the first center shaft of the roller and the first bearing, the first elastic member having a ring shape which surrounds the first center shaft and which has a first inner circumferential surface and a first outer circumferential surface opposite to the first inner circumferential surface; and a first fixed magnet facing the first ring magnet, wherein the first inner circumferential surface of the first elastic member elastically contacts the first center shaft to urge the first center shaft toward the center axis, and wherein the first outer circumferential surface of the first elastic member elastically contacts the first bearing to urge the first bearing away from the center axis.