| 摘要 |
PURPOSE:To enable the reproducing, erasing and recording only by selecting power of a laser and to simplify the constitution by modulating the laser power in a position corresponding to a art of disposing a fixed external magnetic field impressing means. CONSTITUTION:A recording medium (disk) 1 consisting of an auxiliary magnetization layer and a main magnetization layer on a nonmagnetic substrate is rotatively driven by a motor 7, and given a prescribed external magnetic field by the DC external magnetic field impressing means 4, and then irradiated with the laser beam 6 in a 1st temp. range where the main magnetization layer will have holding force larger than the max. external impressing magnetic field to perform the reproducing, while the erasing is performed in a 2nd temp. range which is lower than a temp. of neighbourhood of a magnetic compensation temp., where the main magnetization layer and the auxiliary magnetization layer will have holding force smaller than the max. external impressing magnetic field, and moreover the recording is performed in a 3rd temp. range which is higher than the temp. of neighborhood of the magnetic compensation temp. By this constitution, the recording, reproducing and erasing operations can individually be performed by impressing a shared DC magnetic field and also only by modulating shared laser power, thus simplifying the constitution. |
