| 摘要 |
PURPOSE:To improve remarkably the C/N of a reproducing signal by providing a permanent magnet to a cylindrical nonmagnetic holding member having a prescribed interval with an photomagnetic disc and arranged in the radial direction. CONSTITUTION:The cylindrical nonmagnetic holding member 13 provided with the permanent magnet 11 is arranged above the photomagnetic disc 2 with a prescribed interval. The magnet 11 is parted from the disc 2 at recording and turned by 180 deg. at erasure to bring its magnetic field larger than the bias magnetic field at recording. Thus, the bias magnetic field close to the relation of strength at recording and erasure is impressed respectively to the photomagnetic disc to improve remarkably the C/N of the reproducing signal.
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