| 摘要 |
PURPOSE:To rewrite recorded information by changing the intensity of a laser light irradiated to a recording medium in the state where a certain magnetic field is impressed from external to the recording medium consisting of a magnetic thin film having a vertical magnetic anisotropy. CONSTITUTION:Binary signal information (a) is recorded on a photomagnetic disc 1 along a disc track, and the magnetization state of a magnetic thin film 3 is shown by (b). In case that binary signal information (a) is rewritten with binary signal information (c), a laser light source modulation circuit 17 is so adjusted that the power of the laser light absorbed by the magnetic thin film 3 becomes a level indicated by (d). At this time, a certain magnetic field Ha is impressed to the magnetic thin film 3 by a magnetic field impressing coil 11. When information (c) is recorded over information (a) on the magnetic thin film 3 by the power of the laser light indicated by (d), the magnetization state of the magnetic thin film 3 is shown by (e) and is converted to a form corresponding to binary signal information recorded newly by irradiation of the laser light, and thus, recorded information is rewritten. |
