| 摘要 |
PURPOSE:To attain zero erasion with low power consumption by reducing the remaining magnetic flux density of a tape by plural magnetized parts having different polarity with each other and attenuated gradually and passing the tape through a gap part generating an alternating magnetic field. CONSTITUTION:An erasing head 9 consists of plural magnetic core parts 10 having different magnetic poles alternately and attenuated gradually on the downstream side, a shielding plate 11, an AC erase core part 12, and a gap part 13. The intensity of the erasing magnetic field applied to the magnetic tape 5 in the process travelling the core parts 10 and the gap part 13 is the value shown in the figure. In the figure, the magnetic fields H'1-H'4 are generated by the magnetic core parts 10 and the remaining magnetic flux density of the tape 5 becomes B'x. Since B'x is sufficiently smaller than the saturated magnetic flux density of the tape 5, the tape 5 receives an AC magnetic field HAC by the erasing magnetic field generated in the gap part 13 when AC fine erasing current is made flow into the winding part of the AC erasing core part 12. Consequently, zero erasion is attained in the same manner as an ordinary AC erasing head device. |
