Patent ID: 8156833

Claim:
A linear actuator comprising: an alternating drive apparatus for generating drive force back and forth in an axial direction, an alternating motion member for executing alternating motion with a micro amplitude by the alternating drive apparatus, a fixing member fixed to a housing member, a direct acting member for executing direct motion back and forth in the axial direction, a first wedge joining mechanism incorporated between the alternating motion member and the direct acting member for permitting a relative displacement in one axial direction and inhibiting a relative displacement in the other axial direction, and a second wedge joining mechanism incorporated between the fixing member and the direct acting member for permitting a relative displacement in one axial direction and inhibiting a relative displacement in the other axial direction, wherein: the first wedge joining mechanism and the second wedge joining mechanism include an inclined surface composed of an inclined surface at a distance from a central axis increasing in the axial direction and an inclined surface at a distance decreasing, a non- inclined surface at a constant distance from the central axis, a wedge member arranged between the inclined surface and the non-inclined surface, a holding member of the wedge member for inhibiting wedge joining by the inclined surface, the non-inclined surface, and the wedge member, and a wedge joint inhibition mechanism composed of a drive section of the holding member, and the non-inclined surface of the first wedge joining mechanism and the non-inclined surface of the second wedge joining mechanism are formed on the direct acting member, the inclined surface of the first wedge joining mechanism is formed on the alternating motion member, and the inclined surface of the second wedge joining mechanism is formed to the fixing member.