| 摘要 |
PURPOSE:To attain position control, by floating an objective lens of an optical head in space with a magnetic force without using an elastic support member to prevent resonance and parasitic oscillation. CONSTITUTION:A nonmagnetic cylindrical member 11 is fixed to a barrel 2 of a lens 1 and the 1st ring-shaped permanent magnets 12a, 12b are fixed to both ends. In this case, the outer side is set as, e.g., an N pole. Further, a driving coil 13 is wound around the cylindrical member 11. The 2nd ring-shaped permanent magnets 14a, 14b are fixed to the nonmagnetic fixed section 16 so as to be opposed to the 1st permanent magnet. In this case, the inside is set as the N pole. Moreover, ring-shaped magnetic members 15a, 15b are fixed as shown in a figure and the magnetic field of the 2nd permanent magnet is directed to the inside to produce a repulsive force at right angles to the optical axis. Then, the lens section is held in space with the repulsive force between both the permanent magnets. The repulsive force is balanced radially and in the optical axis direction to hold correctly the objective lens in space. The moving section is at a standstill at the balancing position by detecting deformation of a disc and applying a current to the driving coil 13 so as to compensate the deformation. |
