| 摘要 |
PURPOSE:To prevent the occurrence of data read error due to dirt of a head and to improve the reliability for a long period by using a ferromagnetic metallic powder in a magnetic layer to limit the surface roughness in the diametral direction of a disc to a specific range. CONSTITUTION:With respect to a disc cartridge where a magnetic disc 9 where a magnetic layer 11 is coated on a base film 10 as a nonmagnetic supporting body is stored freely rotatably in a cartridge, a ferromagnetic metallic powder is used in the magnetic layer 2, and the surface roughness of the disc 9 in the diametral direction is set to >0.025mum and <=0.040mum. Thus, the dirt of the head and slide flaws are not recognized, and the tracks are traversed smoothly, and the running is stable, ad the disc cartridge is used for a long period at ease.
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