Patent ID: 8020463

Claim:
A rotation/linear motion converting mechanism including a shaft having a thread on an outer circumferential surface, a nut having a thread on an inner circumferential surface, and a roller arranged between the outer circumferential surface of the shaft and the inner circumferential surface of the nut, the roller having a thread threaded to the threads of the shaft and the nut, the rotation/linear motion converting mechanism converting rotation of one of the shaft and the nut to linear motion of the other, the mechanism comprising: a first toothed gear provided in a portion of the roller; a second toothed gear provided in a portion of the outer circumferential surface of the shaft that is different from the portion on which the thread is formed, the teeth of the second gear being meshed with the teeth of the first gear; and a third toothed ring gear provided in a portion of the nut and fixed to the inner circumferential surface of the nut, the teeth of the first gear being meshed with both the teeth of the third gear and the teeth of the second gear.