| 摘要 |
PURPOSE:To keep the distance between the surface of a medium and a head constant and to evade the change in the magnetic field strength at a recording position by displacing a magnetic head in the direction perpendicular to the medium surface by following the vibrations even when a recording medium generates surface vibrations and swings. CONSTITUTION:In the upper direction of a magneto-optical disk 10 which is a recording medium, an optical head 16 composed of a semiconductor laser 18, a collimator lens 20, a beam splitter 22, an objective lens 24, a cylindrical lens 26 and an optical sensor 28 is provided. In the lower direction of the disk 10, a magnetic head 40 composed of a soft magnetic core 42 to build in an exciting coil 44 is fitted and provided at an actuator 52 provided at a supporting body 54. The constitution is executed like this, a ferromagnetic field HG is given while a laser beam LB of a constant spot diameter is projected to a recording position 14P, and at this time, when the surface vibration occurs at the disk 10 and a distance D between the recording layer 14 and the head 40 is changed, a focusing error signal PE to occur at a focusing circuit 30 is used, the lens 24 and the actuator 52 are operated and the distance D is kept constant.
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