| 摘要 |
PURPOSE:To ensure a recording having a low distortion and a reduced amount of dropout, by deepening the AC bias value when a recording is carried out with a vapor-deposited metallic tape. CONSTITUTION:The AC bias value when a vapor-deposited metallic tape has its maximum record sensitivity has nearly the same level regardless of the record frequency along with nearly the same trend and degree of level variation. This phenomenon is identical with the tapes having the vapor-deposited thickness of the magnetic layer varying from several hundreds to several thousands Angstrom . Accordingly the AC bias current is increased and both the signal current and the AC bias current are flowed to a recording head to generate an equal magnetic field line (b) that is enough to record the signal on the tape although the gap between the recording head gap and the tape magnetic layer is increased to some extent. Thus the amount of dropout caused in a recording mode can be reduced. The bias current value is set at the point where the level is lowered by 2dB to the maximum sensitivity. |
