| 摘要 |
PURPOSE:To reduce bias-noise while keeping all bands in high reproducing output, by choosing and providing specific surface areas of magnetic powder of the first and second magnetic layers and anti-magnetic force of each magnetic layer etc. on a non-magnetic substrate and thereon by forming >=1 layers of magnetic metallic thin films. CONSTITUTION:After the first magnetic layer 4 contg. metallic (including alloy) magnetic powder having 30-40m<2>/g specific surface area by BET method and which have 2-6mu thickness t1, is formed on a nonmagnetic substrate 1 such as polyethylene terephthalate, the second magnetic layer 5 contg. metallic (alloy) magnetic powder having 35-150m<2>/g specific surface area is formed so as to have 0.2-2mu thickness t2. Further, each of anti-magnetic forces Hc1, Hc2 of the layers 4, 5 is arranged to be Hc1<Hc2. Above one layer e.g. one layer of a magnetic metallic thin film 7, for which its anti-magnetic force Hc3 is chosen to be equal to or more than the anti-magnetic force Hc2 of the layer 5, is formed so as to have 500-1,500Angstrom thickness t3 on the layer 5. By this way, high reproducing output is kept over all band and bias-noise is reduced. |
