| 摘要 |
PURPOSE:To erase completely the recorded bits without producing remaining signals by setting the width of a beam spot of erasion mode in the direction rectangular to the scanning direction at the value larger than the width of the beam spot of record mode in the same direction rectangular to the scanning direction. CONSTITUTION:When the light beam of erasion mode is generated from a semiconductor laser 1 and condensed on a recording medium 14' via a collimator lens 2, a polarizer 3, a splitter 4, a reflection mirror 5 and a tracking mirror 6, the center of the light beam spot draws a locus and oscillates toward an arrow mark with wobbling. A current of the direction opposite to that of a record mode is flowed to a magnetic coil 8 to form a magnetic field in the opposie direction to the record mode. A ferromagnetic thin film layer 14' is heated up to a temperature equal at least to the Curie point by the energy of an effective light beam spot, and the directions of magnetization of the layer 14' are set at random. Then the layer 14' is cooled as soon as the effective light beam goes away and at the sme time magnetized in the direction opposite to a recorded bit by a magnetic field of the coil 8. Thus the recorded bit is erased. |
