Matsushita Electric Industrial Co., Ltd.

Yasuaki Ban

Tatsuaki Ishida

Taizou Hamada

Hideyuki Hashi

Kiyokazu Tohma

Keizo Miyata

Ryuji Sugita

Nobuyuki Komura

Toshio Makabe

Taizo Hamada

Kouji Taniguchi

Kiyokazu Toma

Kaoru Matsuoka

Hiromi Kita

Masaya Sakaguchi

A master information carrier capable of manufacturing a magnetic recording medium in which a preformat recording of information signals causing no reproduction signal detection errors arising from a pulse shift of a reproduction waveform is performed. A master information carrierhas an array of ferromagnetic thin filmsarranged according to the pattern of information signals and is used for forming magnetizationof a pattern corresponding to the array pattern of the ferromagnetic thin filmin a magnetic recording medium by applying a magnetic field while opposing the master information carrieragainst a magnetic recording medium. Each of the ferromagnetic thin filmsis formed such that each pattern length A becomes equal to a length including a correction amount &#x3b1; in addition to a length a between magnetic transition areasof the magnetizationto be formed in the magnetic recording medium

Master information carrier and method for manufacturing magnetic disc using the same

A magnetic transfer method which superposes on a magnetic disk surface a magnetic transfer master disk () on which a magnetic film is formed so as to have an array pattern shape corresponding to a preset information signal, and magnetizes the magnetic film on the master disk () to thereby magnetic-transfer-record the array pattern of the information signal on the master disk () onto the magnetic disk as the magnetized pattern of the information signal, the method characterized by comprising a step of contacting/separating to/from a dummy disk () the magnetic film-formed surface of the master disk () to thereby clean the master disk (), and a step of superposing, after the cleaning, the master disk () on the magnetic disk for magnetic transfer recording; and a magnetic transfer device for the method.

Magnetic transfer method and magnetic transfer device

In a manufacturing method for a magnetic recording medium, when the length of a ferromagnetic thin film on a master information carrier corresponding to the length between a pair of magnetization transition regions adjacent to each other is A in magnetization information recorded onto a magnetic recording medium, the film thickness of the ferromagnetic thin film is t and A/t is k, k is set from not less than 0.8 to not more than 8.

Manufacturing method for magnetic recording medium, and master information carrier used therefor

A master disc capable of conducting a preformat recording by a magnetic transcription without causing any unevenness over an entire magnetic disc is provided. The master disc is provided with a radial land portion where an array of ferromagnetic thin films is formed and a concave portion against the land portion. The land portion and the concave portion are formed such that the land portion is joined with the surface of the magnetic disc when the present magnetic disc is overlapped on the magnetic disc, and that the concave portion is not contacted with the surface of the magnetic disc, and also that a space surrounded by the surface of the magnetic disc and the concave portion is open to air at a peripheral end portion of the magnetic disc.

Master disc and method for manufacturing magnetic disc using the same

The master information recording apparatus 100 includes a master information carrier, a master information carrier facing member, and a magnetic field applying member. A ferromagnetic thin film pattern formed on the surface of the master information carrier includes not less than two kinds of different patterns each having a different pattern angle showing an angle with respect to the direction of the relative movement between a magnetic head and a rotating magnetic recording medium. The magnetic field applying unit applies a magnetic field along the direction, which is perpendicular to the direction shown by an angle that is smaller than the pattern angle of the maximum pattern and larger than the minimum pattern angle of the pattern among the not less than two kinds of patterns.

Master information magnetic recording apparatus and method for manufacturing magnetic recording medium in which information is recorded by using this

The data row Pw(i) of phase information obtained by reading preformatted phase patterns on an information recording medium by the head consists of the remainders obtained by dividing the data row of the phase information indicating the original track location by 2&pgr;. The data row Pw(i) in a convoluted state is entered; a data row dPw(i) consisting of the differential values between adjacent data in the data row Pw(i) is generated; a two-step differential data row &dgr;Pw(i) consisting of the differential values between adjacent data in the data row dPw(i) is generated; the cumulative coefficient k(i) is adjusted according to the section region where the value of the two-step differential data row &dgr;Pw(i) belongs; a differential data row dPu(i) (&equals;&dgr;Pw(i)&plus;2&pgr;&times;k(i)) is generated by applying a reconstructing process for solving the convolution process with the use of the found cumulative coefficient k(i); and a reconstructed phase information data row Pu(i) is obtained by further applying integration.

Method for reproducing phase information signals in an information recording device

A magnetic transcription device for transcribing information signals of a master information carrier in a magnetic recording medium by applying a magnetic field generated by magnetic field generating means to a contact body obtained by contacting the master information carrier having a base on which ferromagnetic bodies corresponding to the information signals are formed with a magnetic recording medium having a ferromagnetic layer, wherein the magnetic recording medium includes driving means for adjusting a distance between the magnetic field generating means and the contact body while rotating the magnetic field generating means relative to the contact body. Accordingly, an external magnetic field can be applied and removed for transcription of the information signals of the master information carrier in the magnetic recording medium while rotating the magnetic field generating means relative to the contact body, so that the deterioration of reproduction signals from the magnetic recording medium can be prevented.

Magnetic transcription device

A magnetic transfer method which superposes on a magnetic disk surface a magnetic pattern from a master disk ( ), said master disc having on its surface a magnetic film formed so as to have an array pattern shape corresponding to a preset data signal, magnetized into the magnetic film of the master disk ( ). The master disc is used to magnetically transfer the array pattern of the data signal onto the magnetic disk as the magnetized pattern of the data signal. The method characterized comprises steps of contacting and separating, to and from a dummy disk ( ) the magnetic film-formed surface of the master disk ( ) to thereby clean the master disk ( ), and a step of superposing, after the cleaning, the master disk ( ) on the magnetic disk for effectuating the magnetic transfer.

A master information carrier ( ) with an arranged pattern formed of a ferromagnetic film in a shape corresponding to information signals is superposed on a magnetic recording medium ( ) and the arranged pattern formed of a ferromagnetic film is magnetized with a magnetizing head ( ), thus transfer-recording the arranged pattern into the magnetic recording medium as a magnetized pattern. The magnetizing head includes an annular magnetic circuit with a gap, and a strength of a magnetic field applied to the master information carrier by magnetic flux leaking from portions other than the gap is set to be 20% or less of that of a magnetic field applied to the master information carrier by magnetic flux leaking from the gap. Quality deterioration due to various conditions during recording can be prevented and uniform recording with less variation depending on position on the magnetic recording medium is achieved.

Method for recording magnetic recording medium

A magnetic tape having a polymer substrate and a magnetic layer which is formed directly on a surface of the substrate or on a primer layer formed on the substrate and contains cobalt, oxygen and optionally nickel, in which a coercive force is at least 120 kA/m and a squareness ratio is at least 0.9 in a hysteresis loop which is obtained when a magnetic field is applied in a plane of the magnetic layer in a longitudinal direction of the magnetic tape, and on the hysteresis loop, an intensity of the applied magnetic field, at which a magnetization when the applied magnetic field is increased is 99% of the magnetization when the applied magnetic field is decreased, is not larger than 400 kA/m, and preferably, a ratio of a value of magnetization at an intersection between a tangential line drawn at a point which gives a residual magnetization at the applied magnetic field of 0 (zero) and a tangential line drawn at a point which gives a coercive force with a magnetization of 0 in a second quadrant to said residual magnetization is at least 0.9, which magnetic tape has improved high density recording/reproducing properties.

Magnetic recording medium and method for producing the same

A magnetic recording medium has a cobalt-based first magnetic layer and a cobalt-based second magnetic layer which are formed on a substrate of high polymer by vacuum evaporation. In order to have a high reproducing output and a high S/N ratio, the first magnetic layer has high oxygen density area which is arranged at a vicinity of the second magnetic layer, and the second magnetic layer has high oxygen density area which is arranged at a vicinity of the first magnetic layer.

A magnetic recording medium having good high density recording characteristics is produced by forming a magnetic layer on a substrate which is traveling around a peripheral surface of a cylindrical can by an oblique vapor deposition method to form a magnetic layer comprising cobalt, an axis of easy magnetization of which inclined from a line normal to the layer plane. A residual gas pressure in an initial region of the formation of the magnetic layer is kept as low as possible, in particular, the residual gas pressure in the initial region of the formation of the magnetic layer is lower than in the other part of the production apparatus.

Method and apparatus for producing magnetic recording medium

Method for producing magnetic recording medium

A magnetic recording medium includes a nonmagnetic substrate and a magnetic layer which is formed on a surface of the substrate and which has an axis of easy magnetization inclined from a direction to normal plane of the layer. An angular dependency of coercive force, of the medium which is measured by changing an application angle of a magnetic field in a range relative to -90.degree. to +90.degree. from the plane of the layer with a plane normal to the layer and including the axis of easy magnetization, has two local maximum values and two local minimum values. A ratio of the local maximum value closer to a plane direction to the minimum value closer of the layer to the local plane direction of the layer is from 1.6 to 2.4, and the local maximum value closer to the plane direction of the layer is larger than the local maximum value closer to the line normal to of the plane of the layer. The medium has a high S/N ratio.

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Hirakata, Japan

Yasuaki Ban