| 摘要 |
PURPOSE:To permit erasure of recording information only on the arbitrarily selected face over the entire surface without affecting the recording information on the other face by using compsns. which are different in coercive force to constitute the magneto- optical media on the respective faces of the magneto-optical memory medium formed with the magneto-optical medium layers on both the front and rear faces. CONSTITUTION:The coercive force of the magneto-optical medium 3 on one face is preset in the state of the high coercive force A and the coercive force of the magneto-optical medium 4 on the other face in the state of the high coercive force B or C. The intensity H of the external magnetic field at the time of erasing is set at Ha<H<Hb and is impressed over the entire surface of the magneto-optical disk in the case of erasing the recording information on the face in the state of A over the entire surface without affecting the other face side in the state of B. No magnetical influences are thereby exerted to the magneto-optical medium 4 at all, but the recording information on the magneto-optical medium 4 at all, but the recording information on the magneto-optical medium 3 side is erased over the entire surface. Erasure of only the recording information on the face side in the state of B is executed by increasing the atmosphere temp. by DELTAT and erasing the information in the state of reversing the high and low coercive force of the front and rear faces. |
