| 摘要 |
PURPOSE:To directly execute overwriting without executing an erasion once, by providing an external write coil, and prescribed a direction of a recording magnetic field by turning on and off this coil at the time of write heating by laser light. CONSTITUTION:At the time of writing in the upward direction (shown in a figure) of a write magnetic field Ho in a magnetic domain of a recording layer 5, when its magnetic domain is projected by strong laser light 9 and heated to the vicinity of a curie temperature, its holding force drops to Hr. In this case, the magnetic field Ho is impressed by a write coil 8, and when a condition of Hr<Ho-Hi (Hi denotes a magnetic field by a thin film permanent magnet 2) is set, a magnetic field of its magnetic domain is governed in the upward direction (shown in figure) of the magnetic field Ho. As a result, a disk advances by one magnetic domain portion, and in the magnetic domain after the laser light 9 has been eliminated, a magnetization in the upward direction is left as a residual magnetism. Subsequently, in case of overwriting in the downward direction , the magnetic field Ho is not impressed, and an external magnetic field for governing the magnetic domain being a write part is only the magnetic field Hi. Accordingly, a condition of Hi>Hr is set by the laser light 9, and the direction of its magnetization is inverted in the downward direction and recorded. |
