Patent ID: 8656810

Claim:
A wave-type linear motion mechanism comprising: a rigid screw member; a circular flexible screw member able to flex in a radial direction; and a wave generator, wherein a female screw is formed on one of the rigid screw member and the flexible screw member, and a male screw is formed on the other, the male screw being capable of meshing with the female screw and having a different lead; one of the rigid screw member and the flexible screw member is an immobile-side member, and the other is a mobile-side member, the immobile-side member not moving in an axial direction, and the mobile-side member being capable of moving in the axial direction; and the wave generator creates a state in which the flexible screw member is flexed into a non-circular shape and made to mesh in at least one location in a circumferential direction with the rigid screw member, causes a meshing position of the two screw members to move in the circumferential direction along with rotation of the wave generator, and generates relative linear motion between the two screw members in the axial direction, the wave-type linear motion mechanism having retention-force-generating means for generating at least a part of a retention force for retaining the mobile-side member in a stopped position in the axial direction when the wave generator is in a rotationally stopped state.