| 摘要 |
In an objective lens actuator, when an action force generation force including a focus coil and a magnetic circuit generates an action force for displacing an objective lens holder in a focus direction of an optical disk, a leaf spring supports the magnetic circuit with respect to an actuator base, in such a manner that the magnetic circuit can be rotated about an arbitrary point in the leaf spring, by a reaction force of the action force. At the same time, the equation a=I/Mh is satisfied, where M is a mass of the magnetic circuit, I is a moment of inertia of the magnetic circuit about a center of gravity, a is a distance between the center of gravity of the magnetic circuit and a line of action in a direction of the action force, and h is a distance between a center of rotation in the leaf spring and the center of gravity of the magnetic circuit. As a result, even if the reaction force of the action force acting on the objective lens holder is generated, stable focus servo can be performed, and the actuator can be downsized with a simple structure.
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