| 摘要 |
PURPOSE:To constantly keep the magnetic field strength added to the recording surface of a disk, by extracting the signal in proportion to an objective lens shifting quantity out of a focus servo mechanism, correcting a magnetic setting signal in accordance with the size and changing an electromagnetic current. CONSTITUTION:A signal Ea extracted from a focus servo mechanism 8 and added to an LPF 11 is in proportion to a driving current of a lens driving device 6. A signal E'a through the LPF 11 is in proportion to the shifting quantity of an objective lens 5, and this is added to an electromagnetic driving circuit 10. By the driving circuit 10, a magnetic field setting signal Sm is corrected in accordance with the signal E'a and a corresponding driving current im is supplied to an electromagnet 9. When a magneto-optical disk 1 raises from a reference condition x=0, the signal E'a is increased. When the electromagnet 9 is driven with a corrected signal Sm, a generating magnetic field strength is changed in accordance with the distance of the magnet 9 and the recording surface of the disk 1, a magnetic field intensity H added to the recording surface is constantly kept and the quality of the signal recorded is improved. |
