Patent ID: 7755666

Claim:
An actuator comprising: a fixed member; a movable member having a locking element; movable member supporting means for supporting the movable member so as to permit the movable member to move to an arbitrary position in a plane in parallel with the fixed member; drive means for translating and rotating the movable member relative to the fixed member, an engagement member engaged with the locking element to lock the movable member when the movable member has been rotated to a predetermined position; and wherein the movable member is shaped approximately as a disk, the locking element is formed with at least three engagement projections extending outwardly in radial directions, and the engagement member is annular in shape, surrounding the outer circumferential surface of the movable member, and is provided with engagement projection contacts protruding inwardly in the radial directions on which the engagement projections fit when the movable member is rotated to the predetermined position.