Fuji Photo Film Company, Limited

Junichi Nakamikawa

Hitoshi Noguchi

Shinji Saito

Masatoshi Takahashi

Masakazu Nishikawa

Kazunori Komatsu

Nobuo Yamazaki

Hiroaki Doushita

Masashi Aoki

When a master medium and a slave medium are brought into close contact and a transfer magnetic field is applied thereto to perform magnetic transfer, the leakage magnetic field intensity of the transfer magnetic field is regulated to within a permissible range, making possible the transfer of an exact magnetic pattern. After a magnetic field is applied to the slave face in the track direction thereof to initially magnetize the slave medium in the track direction, the master medium and the slave medium are brought into close contact. When applying a transfer magnetic field in the track direction of the slave face to perform a magnetic transfer, the magnetic field intensity component in the direction opposite that in which the transfer magnetic field is to be applied is regulated to less than or equal to &#xbd; the magnetic coercive force Hcs of the slave medium over the entire slave surface.

Magnetic transfer method and apparatus

A flexible magnetic recording medium includes a non-magnetic layer and a magnetic layer consisting of ferromagnetic powder dispersed in binder which are formed on a base sheet in this order. The ferromagnetic powder is not smaller than 158 kA/m in coercive force Hc(VSM) as measured by a vibrating sample magnetometer and is not larger than 100 in KuV/kT (wherein Ku represents an anisotropy constant, V represents a volume, k represents a Boltzmann constant and T represents an absolute temperature) which is a parameter of thermal fluctuation, and a magnetization pattern representing predetermined information has been formed on the magnetic layer by magnetic transfer.

Magnetic recording medium

A process for producing a magnetic disk having a randomly oriented magnetic powder, comprises: applying a magnetic coating solution containing at least a magnetic powder to a web that is being continuously conveyed, so as to prepare a magnetic layer; applying a first external magnetic field to the magnetic layer while the magnetic layer is wet; and applying a second external magnetic field to the magnetic layer while the magnetic layer is wet, wherein: the first external magnetic field is applied with a set of a first pair of same-pole-opposed magnets with the web interposed therebetween and a second pair of same-pole-opposed magnets with the web interposed therebetween; the first and second pairs are provided on the same plane of the web and on two equal sides of an isosceles triangle so that a perpendicular line dropped from a base of the isosceles triangle forms a line perpendicular to a conveying direction of the web; and the second external magnetic field is an alternating magnetic field, and is applied with a pair of magnets with the web interposed therebetween; the pair of magnets being provided on the same plane of the web, and in a direction perpendicular to the conveying direction of the web.

Process for producing magnetic disk

A magnetic recording medium is described, which comprises a support having thereon a substantially nonmagnetic lower layer and a magnetic layer comprising a ferromagnetic metal powder or a ferromagnetic hexagonal ferrite powder dispersed in a binder provided on the lower layer, which is a magnetic recording medium for recording signals of from 0.17 to 2 G bit/inch of areal recording density, wherein the dry thickness of the magnetic layer is from 0.05 to 0.30 &mgr;m , &phgr;m is from 10.0&times;10 to 1.0&times;10 emu/cm , the coercive force of the magnetic layer is 1,800 Oe or more, and a filler having an average particle size of from 0.05 to 0.3 &mgr;m is present on the surface layer of the support in an amount of from 5,000,000 to 30,000,000/mm .

Magnetic recording medium comprising a support containing a specific size filler and having a specific concentration of surface protrusions

A magnetic recording medium which comprises a support having thereon a substantially nonmagnetic lower layer and a magnetic layer comprising a ferromagnetic metal powder or a ferromagnetic hexagonal ferrite powder dispersed in a binder provided on the lower layer, which is a magnetic recording medium for recording signals of from 0.17 to 2 G bit/inch,of areal recording density, wherein the coercive force of the magnetic layer is 1,800 Oe or more, and the thickness unevenness of the support is 5% or less of the thickness of the support.

Growing community of inventors

Kanagawa-ken, Japan

Junichi Nakamikawa