| 摘要 |
PURPOSE:To enable easy detection of the deviation in the track position of a recording medium by forming a ferromagnetic material layer which has a hexagonal planar shape and has the axis of easy magnetization in a perpendicular direction on one surface of a non-magnetic base and a rice grain-like ferromagnetic layer having >=60emu/g saturation magnetization on the other surface. CONSTITUTION:Magnetic paint prepd. by kneading and dispersing a ferromagnetic material such as barium ferrite in a binder, additive, solvent, etc. is coated, oriented and dried on one surface of a non-magnetic polyester terephthalate film base to form the layer which has the hexagonal planar shape and has the axis of easy magnetization in the direction perpendicular to the flat plane. The layer contg. the cobalt-added iron oxide ferromagnetic material which is elliptical and has a long axis-short axis ratio of 1.5 or above and >=60emu/g saturation magnetization is formed on the other surface of the base. The reproduced output of the recording medium constituted in such a way is measured and the decrease in the value thereof indicates the deviation in the track position owing to the shrinkage of the recording medium by the effect of heat and moisture. The easy detection of the deviation in the track position is thus made possible by the rice grain-like magnetic particles.
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