| 摘要 |
PURPOSE:To make it possible to erase recorded signals on high performance antimagnetic tapes by a method wherein a piece of magnetic substance is produced in which ratio of anisotropy is distributed in such a manner as it is reduced gradually from the entry side toward the exit for the tape running on this magnetic material which has been magnetized so as to form a multipolar magnetism magnet. CONSTITUTION:When powder magnetic substance is press-formed, a magnetic field N-S is caused to produce at the tips of an upper punch 3 and a lower punch 4 which are located between metal dies 2a, 2b of non-magnetic substance and, in addition, spacers 5, 6 of non-magnetic substance which are to be thicker toward the direction of tape running on this product as used as an erasing head are fitted to vary strength of the magnetic field, so that the ratio of anisotropy due to orientation of the magnetic field is varied in accordance with a predetermined gradient for formation of the powder magnetic substance. The formed product is then burned and the magnetized surface is ground which has been magnetized in such a manner that magnetic poles N's and S's are arranged alternately with their degrees of magnetization being gradually reduced respectively. By such a procedure, a multipolar magnet can be produced which can erase recorded signals on high performance antimagnetic tapes. |
