| 摘要 |
PURPOSE:To obtain a magnetic recording and reproducing device capable of overwriting without necessitating an erasing operation, by discriminating the number of times of the overwrite of a sector by reading a flag in the sector on a recording medium, and performing the switching of an external magnetic field and the ON/OFF control of the delay of a recording information pulse corresponding to the number of times of the overwrite. CONSTITUTION:The magnetizing direction 22 of an information cell 23 of one bit with a cycle T faces upward and shows 0 initially. The information 25 of 1101 is recorded by aligning the trailing edge of laser pulse light with the start point of the cell, projecting the light setting width lens than T/2, simultaneously applying the external magnetic field 23 in a direction of arrow head, and inverting the magnetizing direction of only a projecting part. When the overwrite is performed, by inverting the direction of the external magnetic field 26 and projecting a recording waveform in which a pulse falls in a center part, a magnetizing pattern 27 is formed, and a magnetizing pattern 24 is erased completely, then, a new state 1011 is recorded. By adopting the said method, it is possible to make the erasing operation unnecessary and to perform recording in a real time. |
