BIAS MAGNETIC FIELD GENERATOR

摘要

PURPOSE:To almost fix the position of a magnetic field applied to an optional spot of a medium based on an optional access position of an optical head by magnetically saturating a coil winding part to suppress an output from a magnetic field at a position separated from the center part of an access range of the optical head. CONSTITUTION:A winding part 6a of an exciting coil 7 is formed so that its width is most expanded at a position corresponding to the intermediate point in the access range of the optical head and narrowed in accordance its separation along the access direction. Thereby, the distribution of magnetic field intensity obtained on the recording face of the medium corresponding to the access position is constituted so that the magnetic field intensity on both end parts of the access range are almost the same as that of the center part without being increased. Since magnetic saturation is generated by a low current value in accordance with the efficiency of an output magnetic field to a driving current, the output magnetic field can be suppressed. Consequently, the magnetic field applied to the optical spot position of the medium can be almost fixed about an optional access position of the optical head.