Hitachi, Ltd.

Kenya Ito

Masaaki Futamoto

Yoshiyuki Hirayama

Yukio Honda

Nobuyuki Inaba

Kazuetsu Yoshida

Kazusuke Yamanaka

Magnetic recording medium includes at least two layers having different magnetic anisotropy constants formed on a substrate and the perpendicular magnetic anisotropy of the second magnetic film of those magnetic films, far from the substrate surface, made equal to or larger than that of the first magnetic film near to the substrate surface, thus improving the magnetic isolation.

Magnetic recording medium and magnetic recording apparatus using the same

A time counting device, a cache memory and a copy control circuit are added to a conventional disk drive so that recorded information is copied periodically and automatically. Alternatively, a cache memory, a copy control circuit, a reference control circuit, a first time counting device and a second time counting device are added to the conventional disk drive so that information which remains recorded for a predetermined period of time after its last recording date is automatically copied. According to another embodiment, a reference signal is recorded in advance and a reproduced output is periodically measured. If the reproduced output is lower than a reference value, recorded information is automatically copied. Other embodiments are also disclosed with the aim of ensuring that information recorded on a magnetic media can always be reproduced reliably, even in the case of high density recording.

Storage device for reliably maintaining data in a reproducible state for a long period of time

Magnetic recording medium includes at least two layers having different magnetic anisotropy constants formed on a substrate and the perpendicular magnetic anisotropy of the second magnetic film of those magnetic films, far from the substrate surface, made equal to or larger than that of the first magnetic film near to the substrate surface, thus improving the magnetic isolation of the first magnetic film near to the substrate surface.

A time counting device, a cache memory and a copy control circuit are added to a conventional disk drive so that recorded information is copied periodically and automatically. Alternatively, a cache memory, a copy control circuit, a reference control circuit, a first time counting device and a second time counting device are added to the conventional disk drive so that information which remains recorded for a predetermined period of time after its last recording date is automatically copied. According to another embodiment, a reference signal is recorded in advance and a reproduced output is periodically measured. If the reproduced output is lower than a reference value, recorded information is automatically copied. According to yet another embodiment, the temperature in the disk drive is measured by a thermometer,, and if the temperature is higher than a reference value, information is automatically copied at shorter intervals than when the temperature is less than the reference value. Other embodiments are also disclosed with the aim of ensuring that information recorded on a magnetic media can always be reproduced reliably, even in the case of high density recording.

Perpendicular magnetic recording medium and magnetic storage apparatus using the same

A perpendicular magnetic recording medium is provided by using a ferromagnetic polycrystalline thin film having main components of cobalt and chromium in which the coercivity is 1500 oersted or more and the fluctuation field of magnetic viscosity is 30 oersted or more; the film thickness is controlled within a range from 30 nm to 100 nm. A perpendicular magnetic recording medium with low noise and high output which is suited for high density recording can be obtained and a large capacity magnetic recording and reproducing apparatus can be provided by using this medium.

Perpendicular magnetic recording media and magnetic recording and

A time counting device, a cache memory and a copy control circuit are added to a conventional disk drive so that recorded information is copied periodically and automatically. Alternatively, a cache memory, a copy control circuit, a reference control circuit, a first time counting device and a second time counting device are added to the conventional disk drive so that information which remains recorded for a predetermined period of time after its last recording date is automatically copied. According to another embodiment, a reference signal is recorded in advance and a reproduced output is periodically measured. If the reproduced output is lower than a reference value, recorded information is automatically copied. According to yet another embodiment, the temperature in the disk drive is measured by a thermometer 18, and if the temperature is higher than a reference value, information is automatically copied at shorter intervals than when the temperature is less than the reference value. Other embodiments are also disclosed with the aim of ensuring that information recorded on a magnetic media can always be reproduced reliably, even in the case of high density recording.

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Hachioji, Japan

Kenya Ito