Disc-shaped magnetic recording medium
AssigneeSony Corporation
InventorsRyoji Chubachi, Yoshihisa Kawamura, Nobuyuki Nihei
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Abstract
The present invention provides a disc-shaped magnetic recording medium particularly suitable for high density recording obtainable a high output power with low noise. In the disc-shaped magnetic recording medium according to the present invention, a ferromag netic powder having a coercive force of about 1,000 Oe or higher and a BET specific surface area in the range from about 25 to 70 m.sup.2 /g is employed. This allows a decrease in noise level and satisfies the electromagnetic performance requirements for high density recording. A random (unoriented) orientation or a circumferential orientation of the ferromagnetic powder in the magnetic layer provides high output power without causing a variation in output power.
Claims5
A disc-shaped magnetic recording medium characterized in that a non-magnetic substrate is provided with a magnetic layer in which particles of a ferromagnetic powder comprising a metal or an alloy consisting mainly of iron and having a coercive force of about 1,000 Oe or higher and a BET specific surface area in the range from about 25 to 70 m.sup.2 /g are oriented at random or in a circumferential direction, said magnetic layer having a residual magnetic flux density in the circumferential direction of at least 1500 gauss.
Dependencies are inferred from the claim text.