| 摘要 |
PURPOSE:To always execute recording and erasion under a prescribed condition, and also, to miniaturize a device by using jointly an electromagnetic coil and a permanent magnet. CONSTITUTION:A permanent magnet 1 consists of a structure which can rotate around an axis O, and electromagnetic coils 21, 22 are placed in the periphery of the permanent magnet 1. In case a disk 3 has gone away from the permanent magnet, a recording film 31 also goes away from the permanent magnet 1, therefore, the intensity of an applied magnetic field drops. Therefore, when the electromagnetic coils are energized in the direction shown in a figure (a), magnetic fields generated from both the permanent magnet and electromagnetic coil strengthen each other, and a magnetic field HexL applied to the recording film 31 becomes large. On the contrary, in case the disk 3 has approached the magnet 1, the intensity of the applied magnetic field becomes strong, but when the magnet 1 is energized in the direction shown in a figure (b), the magnetic fields generated from both the permanent magnet and electromagnetic coil weaken each other, and the HexL can be made small. In such a way, by controlling a current allowed to flow to the electromagnetic coils 21, 22, the magnetic field applied to the recording film 31 can always be kept constant.
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