BIAS MAGNETIC FIELD IMPRESSING DEVICE OF OPTO-MAGNETIC DISK

摘要

PURPOSE:To prevent the temperature rise of a magnetic field impressing device of an opto-magnetic disk device by using a semihard magnetic material to form a magnetic core having a sufficient distance between N and S poles and impressing an impulsive exciting coil current to the magnetic core to invert the polarity of a magnetic field. CONSTITUTION:A magnetic core 30 having a slender magnetic pole surface M over the entire data area in the radius direction of an opto-magnetic disk 14 is fixed with an about 1mm. gap between the surface M and the disk 14. An exciting coil 31 is wound around a part B opposite to the surface M and then connected to a pulse exciting power supply with a terminal T. Then a laser light beam 9 is irradiated to the disk 14 through an optical system from the side opposite to the surface M of the core 30 for bias magnetic field of the disk 14. Thus the record, reproduction and erasion are carried out. A semihard magnetic material is used to the core 30 and therefore the polarity of the magnetic field is inverted by impressing an impulsive exciting coil current in response to the record and erasion. Thus, the exciting current is reduced and the heat that should be cooled is not generated.