| 摘要 |
PURPOSE:To realize not only the reproduction and addition of recording but the erasion of information for an optical and magnetic recorder and reproducer, by recording and erasing the information in a heat magnetic way by means of the laser beam. CONSTITUTION:An input signal 16 is fed to a laser driving circuit 14 to modulate a laser 13. The modulated laser beam is sent onto a recording medium 4 via a beam splitter 11, a lambda/4 plate 10 and a lens 6. While the reflected beam passes through the lens 6 and the plate 10 to be turned into a linear polarized beam turned by 90 deg. compared with the incident beam. This beam enters a photodetector 12 via the splitter 11 and then led to a head driving circuit 9 in the form of a focus error signal to drive an actuator 8. Thus the distance is set constant between the lens and a recording medium. The signal 16 flows a current to a coil 7 through a driving circuit 15 to apply a magnetic field to the medium 4. The magnetic field applied to the medium 4 is set constant at all times to the face swing of a disk. For this purpose, the output signal of the circuit 9 is fed to the circuit 15. |
