| 摘要 |
PURPOSE:To attain stable recording by always keeping an interval between an external magnetic field generating source and a magneto-optical recording medium constant so as to apply a constant external magnetic field onto the film face. CONSTITUTION:An electromagnetic coil 3 fixed to an electromagnetic coil holder 4 provided with a core rod is placed at the rear side of an electromagnetic coil 1. The electromagnetic coils 1, 3 are connected by an elastic body 5 such as a spring. The electromagnetic coil 1 is moved vertically by the strength of the repulsion force between a constant magnetic field 7 generated from the electromagnetic coil 1 and a variable magnetic field 6 generated from the electromagnetic coil 3. In order to keep the interval between the recording medium 2 and the electromagnetic coil 1 constant, a focus error signal 14 is converted into a current flowing to the electromagnetic coil by a converter 16 to vary the magnetic field 6 corresponding to the focus error signal thereby making the distance between the electromagnetic oil 1 and the recording medium 2 constant. Thus, crash between the magnetic field generating source and the recording medium is prevented and the magnetic field at the film face is made constant. |
