| 摘要 |
<p>PURPOSE:To make it possible to conduct a high-speed switching of large magnetic field as well as to improve the record-erasing characteristics of a photomagnetic device for recording, reduction, and erase by a method wherein a high permeability ferromagnetic cylindrical member, having a wire-wound protrusion on one end of the inner wall, and a cylindrical permanent magnet, arranged in such a manner that its projection is positioned in close vicinity to the internal part of the above-mentioned ferromagnetic member, are provided. CONSTITUTION:As a magnetic path, with which the magnetic flux 8 and 9 generated from the N-pole of a permanent magnet 2 is led to the S-pole in a highly efficient manner on a high permeability ferromagnetic member 3, the upwardly generating magnetic field from the N-pole becomes small. On the other hand, when a current I is applied to a winding 4, the magnetic flux leaks out to the outside from the N-pole in the amount of magnetic flux generated in the high permeability ferromagnetic member by the current I. As a result, bias magnetic field is applied upwardly from the N-pole. The intensity of magnetic field in the upper part of the magnetic pole of the permanent magnet 2 can be selected by adjusting the value of current allowed to flow on the winding 4. Accordingly, the vertical magnetic field of several hundred oersteds can be switched at several MHz at a place separated from the N-pole edge face by several mm.</p> |
