| 摘要 |
PROBLEM TO BE SOLVED: To stabilize an optical characteristic by making constant a dynamic change in the inclination of a movable piece in a gap between the bearing part of a lens holding member and a rotary shaft. SOLUTION: This actuator comprises a rotary shaft 8 fixed in a base 7, an objective lens 2, a movable piece 11 attached to the rotary shaft 8 to be rotated and freely slid, an electromagnetic coil 4 wound on a lens holding member 3 so as to cover a magnetic material 6 attached to the lens holding member 3 and at least a pair of permanent magnets 9 fixed in the base 7 in a position away from and opposite the electromagnetic coil 4. The length of the magnetic material 6 in the axial direction of the rotary shaft 8 is set larger than that of at least the permanent magnet 9, two projecting parts 3b and 3c in a bearing part 3a for inserting the rotary shaft 8 of the lens holding member 3 at an internal larger than the length of the magnetic material 6 and, by means of a magnetic force produced between the magnetic material 6 and the permanent magnet 9, the two projecting parts 3b and 3c are pressed and contacted with the rotary shaft 8. Thus, inclination between the bearing part 3 and the rotary shaft 8 is kept constant. |
