| 摘要 |
PURPOSE:To perform recording and reproducing stably for a long time by changing the intensity of a magnetic field in accordance with the output of a laser beam when the laser beam is irradiated to a magnetic medium, which is magnetized in one direction, and the magnetic field in the opposite direction is applied thereto. CONSTITUTION:A tape as a magnetic medium 1 is magnetized in one direction by a magnet 2, and the tape is irradiated with a laser beam 13 modulated by a signal 3 and the magnetic field in the opposite direction is applied to the tape by an electromagnet 6. At this time, the current of the electromagnet 6 is controlled by a controller 7 which is controlled by the output of an optical sensor 8 such as a phototransistor or the like. The magnetic field is increased when the laser output is reduced, and the magnetic field is reduced when the laser output is increased. Thus, an automatic control system is used to perform recording and reproducing stably for a long time. |
