| 摘要 |
PURPOSE:To eliminate a slump of frequency characteristics and to improve the sensitivity with reduction of noises by forming a lower magnetic layer containing metallic magnetic powder with the coercive force set within a specific range and an upper magnetic layer containing iron nitride magnetic powder with the coercive force set equal to or higher than that of the lower layer on a supporter. CONSTITUTION:The 1st magnetic layer containing the metallic magnetic powder having 600-1,300 Oe coercive force is formed on a supporter of a polyester film, etc. Then the 2nd magnetic layer containing the iron nitride magnetic powder having the coercive force set equal to or higher than the 1st layer is formed on the 1st magnetic layer. The ratio of thickness is preferably set within a (1:1)- (1:10) range between both magnetic layers. The characteristics of a low-frequency band are not improved if the upper magnetic layer is too much thicker than the lower layer, while the characteristics of a high-frequency band are not satisfactory if the upper layer is too much thinner than the lower layer with unsatisfactory reduction of noises. In such a way, the excellent characteristics can be secured over a wide range of frequencies for a magnetic recording medium. |
