| 摘要 |
PURPOSE:To secure head quality close to that of an AC erasing head with regard to a noise and distortion, not to mention an erasure rate, by rotating a magnet type erasing head which is formed by magnetizing the surface of a cylindrically shaped magnetic material to an N and an S poles alternately to almost equal magnetic field intensity at a specific speed, and running a magnetic tape. CONSTITUTION:The surface of the cylindrically shaped magnetic material 6 is magnetized to the N and S poles alternately. A surface magnetic field is set above the residual magnetic flux density of the tape to be erased. The magnetized material is linked to a motor 7 through a driving shaft 8 and rotated as shown by an arrow 9. The tape 3 runs to right in contact with part of the surface of the rotating magnetic material 6. One point on the tape aproaches the rotating magnetic material 6 gradually from a far distant point and contacts the magnetic material 6 eventually to be influenced by a maximum magnetic field. Variation of the magnetic field on the tape is in exactly the same shape as variation of the magnetic field applied to the magnetic tape. Therefore, the quality of erasure is close to that of the AC erasing head. |
