| 摘要 |
PURPOSE:To prevent the revolution of a mobile element and to avoid a position shift to the incident light beam of an optical system, by setting a magnetic matter which forms a magnetic path at the mobile element side including the optical system only at a corresponding part to an electromagnet at the fixed side in order to constitute an electromagnetic in the radius direction of a magnetic bearing. CONSTITUTION:A mobile element 100 including an optical system 300 provided with a lens 110 and a mirror 111 is constituted with a magnetic bearing which supports magnetically the element 100 in a floating state. For such head, the electromagnets 104 and 105 in the radius direction of the magnetic bearing are constituted with a magnetic matter 301 which forms a magnetic path at the mobile element side by setting a ring-shaped core 302 having a projected magnetic pole wound with a coil and a nonmagnetic matter 320 at the positions as shown in the diagram. Then the element 100 is set to its original state even if the element is going to turn unless it turns >=45 deg.. As a result, no shift of position is produced for the system 300 to an incident light beam 112. |
