Hitachi Maxell, Limited

Tetsutaro Inoue

Tsugihiro Doi

Sadamu Kuse

Mikio Kishimoto

Seigi Kawarai

Hiroyuki Mitsuhashi

Masao Okafuji

Yuji Sasaki

Hideaki Watanabe

Ken Yoshimura

A magnetic tape produced by cutting a magnetic sheet with a wide breadth into a tape having a predetermined width using a cutting device, in which the magnetic sheet has a magnetic layer containing magnetic powder and a hinder formed on one surface of a non-magnetic substrate having a thickness of 4 &#x3bc;m or less, and a center line average height (Ra) along a roughness curve of a cut edge of the magnetic tape is from 0.08 to 0.25 &#x3bc;m.

Magnetic tape and method for producing the same

A magnetic tape produced by cutting a magnetic sheet with a wide breadth into a tape having a predetermined width using a cutting device, in which the magnetic sheet has a magnetic layer containing magnetic powder and a binder formed on one surface of a non-magnetic substrate having a thickness of 4 &#x3bc;m or less, and a center line average height (Ra) along a roughness curve of a cut edge of the magnetic tape is from 0.08 to 0.25 &#x3bc;m.

In a recording/reproducing method of a magnetic tape in a tracking servo system, a recording density of each data track is increased while inhibiting occurrence of a recording/reproducing error caused by a size change of a magnetic tape in the width direction. Data tracks are each set to have a smaller track width stepwise as closer to servo tracks (T-toT-etc.) in the width direction of a magnetic tape. With such a setting, the width of the data tracks (A-T-to A-T-etc.) closest to the servo tracks (T-toT-) can be minimized, thereby enabling a significant increase in number of the data tracks. Further, even when the size of the magnetic tapechanges in the width direction due to a change in external environment such as a temperature or moisture, to lead to large displacement of the data tracks (A-T-to A-T-) distant from the servo tracks (T-toT-), the data head (A) can be readily aligned to face the data tracks (A-T-to A-T-) in the reproduction by an increased portion of the width size of the data tracks (A-T-to A-T-), and it is thereby possible to ensure reading of data signals from the data tracks (A-T-to A-T-) so as to improve reproduction accuracy.

Recording/reproducing method of magnetic tape

In a recording/reproducing method of a magnetic tape in a tracking servo system, a recording density of each data track is increased while inhibiting occurrence of a recording/reproducing error caused by a size change of a magnetic tape in the width direction. Data tracks are each set to have a smaller track width stepwise as closer to servo tracks (T-toT-etc.) in the width direction of a magnetic tapeWith such a setting, the width of the data tracks (A-T-to A-T-etc. ) closest to the servo tracks (T-toT-) can be minimized, thereby enabling a significant increase in number of the data tracks. Further, even when the size of the magnetic tapechanges in the width direction due to a change in external environment such as a temperature or moisture, to lead to large displacement of the data tracks (A-T-to A-T-) distant from the servo tracks (T-toT-), the data head (A) can be readily aligned to face the data tracks (A-T-to A-T-) in the reproduction by an increased portion of the width size of the data tracks (A-T-to A-T-), and it is thereby possible to ensure reading of data signals from the data tracks (A-T-to A-T-) so as to improve reproduction accuracy.

A magnetic recording medium having a non-magnetic support and a magnetic layer formed thereon, wherein the magnetic layer comprises a ferromagnetic powder, a binder and a non-magnetic inorganic powder, and wherein at least 95% of the non-magnetic powder particles contained in the magnetic layer have a particle size of 0.05 to 0.013 &#x3bc;m, provide that the non-magnetic powder particles are those found in a field of view of 1.8 &#x3bc;m&#xd7;2.4 &#x3bc;m when the surface of the magnetic layer is observed with a scanning electron microscope at a magnification of 50,000 times.

Magnetic recording medium utilizing specified non-magnetic particles in the magnetic layer

A magnetic tape comprising a non-magnetic support, a magnetic layer containing magnetic powder which is formed on one side of the non-magnetic support, a primer layer containing non-magnetic powder which is formed between the non-magnetic support and the magnetic layer, and a backcoat layer containing non-magnetic powder which is formed on the other side of the non-magnetic support, wherein the magnetic layer contains the magnetic powder which comprises plate, granular or ellipsoidal magnetic particles with a particle diameter of 5 to 50 nm, and has a thickness of 0.09 &#x3bc;m or less, and wherein at least one of the primer layer and the backcoat layer contains non-magnetic plate particles with a particle diameter of 10 to 100 nm.

Magnetic tape and magnetic tape cartridge

A magnetic recording medium comprising a non-magnetic support, at least one primer layer formed on one surface of the non-magnetic support, comprising a non-magnetic powder and a binder resin, at least one magnetic layer formed on the primer layer, comprising a magnetic powder and a binder resin, and a back layer formed on the other surface of the non-magnetic support, wherein the magnetic powder contained in the uppermost layer of the magnetic layer is a rare earth metal-iron type magnetic powder of substantially spherical or ellipsoidal particles comprising a rare earth element and iron or a transition metal which comprises iron, and has a number average particle size of 5 to 50 nm and an average axis ratio of 1 to 2, and the total thickness of the magnetic recording medium is less than 6 &#x3bc;m. This magnetic recording medium can achieve an excellent block error rate.

Magnetic recording medium using magnetic powder having a core portion and an outer layer portion including a rare earth element and magnetic recording cassette

A magnetic recording medium comprising a non-magnetic support, at least one primer layer formed on one surface of the non-magnetic support, comprising a non-magnetic powder and a binder resin, at least one magnetic layer formed on the primer layer, comprising a magnetic powder and a binder resin, and a back layer formed on the other surface of the non-magnetic support, wherein the magnetic powder contained in the uppermost layer of the magnetic layer is a rare earth metal-iron type magnetic powder of substantially spherical or ellipsoidal particles comprising a rare earth element and iron or a transition metal which comprises iron, and has a number average particle size 5 to 50 nm and an average axis ratio of 1 to 2, and the total thickness of the magnetic recording medium is less than 6 &#x3bc;m. This magnetic recording medium can achieve an excellent block error rate, which cannot be realized with magnetic recording media comprising conventional acicular magnetic powders.

A magnetic recording medium comprising a non-magnetic support; at least one lower magnetic layer containing magnetic powder and a binder resin, which is formed on one side of the non-magnetic support with or without a non-magnetic primer layer interposed between the non-magnetic support and the lower magnetic layer; at least one non-magnetic intermediate layer containing non-magnetic powder and a binder resin, which is formed on the lower magnetic layer; at least one upper magnetic layer containing magnetic powder and a binder resin, which is formed on the non-magnetic intermediate layer; and a back layer which is formed on the other side of the non-magnetic support, characterized in that the magnetic powder contained in the uppermost magnetic layer of the upper magnetic layer is iron type magnetic powder which comprises substantially spherical or ellipsoidal particles with a number-average particle diameter of 5 to 50 nm and an average axial ratio of 1 to 2, each of said particles containing iron or containing iron as a main component and a transition element; and that the total thickness of the magnetic recording medium is 6 &#x3bc;m or less. This magnetic recording medium has electromagnetic conversion characteristics which cannot be achieved by any of conventional magnetic recording media, and also is expected to have excellent magnetic serve characteristics.

A magnetic tape having a lower non-magnetic layer containing non-magnetic powder and a binder, and an upper magnetic layer containing ferromagnetic powder and a binder, formed on a surface of a tape-form non-magnetic support. This magnetic tape has an intermediate binder layer, which is under the upper magnetic layer and has an average dry thickness of 10 to less than 50 nm. The average dry thickness of the upper magnetic layer is 5 to 100 nm, and the squareness ratio of the upper magnetic layer in the lengthwise direction is 0.8 or more. In this magnetic tape, the thickness of the magnetic layer and the fluctuation at the interface between the magnetic layer and the intermediate binder layer under the magnetic layer can be controlled. As a result, the PW50 value of a solitary waveform and modulation noise can be reduced. Thus, the magnetic tape shows excellent C/N characteristics.

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Ibaraki, Japan

Tetsutaro Inoue