Fuji Photo Film Company, Limited

Fujifilm Corporation

Tadashi Yasunaga

Masakazu Nishikawa

Akio Yanai

Ryuji Shirahata

Kazuhiro Niitsuma

Toshio Ishida

Kazuyuki Usuki

Koji Sasazawa

Yoshihiro Arai

Kazunori Komatsu

Makoto Nagao

Toshihiro Usa

Tsutomu Okita

Ryuji Sugita

Hiroaki Doushita

Masaki Satake

Kunihiko Sano

Shiro Kaneko

Yasuo Nishikawa

Junji Nakada

Hideomi Watanabe

Hideaki Takeuchi

Hiromi Nakahara

Masaru Sekine

Takashi Komine

Kenichi Yoden

Kouichi Mochizuki

Masao Takei

An amplitude servo pattern capable of providing accurate servo control through reproduced amplitude with reduced noise is provided. The amplitude servo pattern has servo burst signals composed of burst bit strings adjacently disposed in a track width direction. The burst bit strings are disposed such that the servo burst signals adjacently disposed in the track width direction have a phase difference with each other in a track direction.

Amplitude servo pattern, magnetic recording medium and the manufacturing method, patterned magnetic transfer master substrate used in the manufacturing method, and magnetic recording/reproducing apparatus

A master information carrier has on its surface a signal area where an embossed pattern formed by protruding portions and recessed portions and representing a signal pattern to be transferred has been formed. The shortest bit length of the embossed patter is 300 nm or shorter, and the embossed pattern is formed so that the total of the areas of the upper surfaces of the protruding portions of the embossed pattern is smaller than the total of the areas of inter-protruding-portions in the signal area.

Master information carrier for magnetic transfer

A master information carrier for magnetic transfer includes a master substrate made of metal, including an embossed pattern corresponding to information to be transferred. The master substrate is produced by laminating a metal disk with a predetermined thickness on an original disk, on which an embossed pattern is formed, by electroforming, peeling off the metal disk and die-cutting a disk in a desired size. An outer diameter of the metal disk is at least 1.7 times longer than an outer diameter of the die-cut master substrate. When the metal disk is peeled off from the original disk, deformation due to the forces acting from the side of the outer circumference is reduced. The flatness of the metal disk is ensured and the transfer qualities are improved. Further, a step of removing distortion of the metal disk, caused at the time of peeling off the metal disk, may also be provided.

Master information carrier for magnetic transfer and its production method

When signals are read out by a magnetic head from a magnetic recording medium on which magnetic bits corresponding to information are recorded along the tracks thereof by a magnetic transfer method, if a space which is longer than or equal to a length corresponding to three bits is present between consecutive magnetic bits, readout of signals from a sub-pulse generation area in the space is cancelled in readout of the magnetic bits by the magnetic head along the tracks. The signals are not read out at all, or even if the signals are read out, they are not processed as valid signals.

Signal processing method of magnetic recording medium and magnetic record reproduction apparatus

A flexible recording medium, which has a track width in the range of approximately 1-3 &#x3bc;m, capable of facilitating good tracking control. A magnetic pattern bearing servo signals is provided on the guard bands formed on both sides of a data track of a magnetic recording medium. An improvement in tracking control is achieved by performing the servo tracking in a continuous manner.

Magnetic recording medium and drive apparatus therefor

A patterned master carrier for magnetic transfer is used to transfer a magnetization pattern, which does not cause a problem such as an error attributable to a subpulse upon signal reproduction, to a slave medium. A signal pattern on a surface of a patterned master carrier for the magnetic transfer includes signal areas and no-signal areas, and the signal area is provided with an actual signal pattern and a dummy signal pattern adjacent to the no-signal area. Therefore, the actual signal pattern is not adjacent to the no-signal area.

Patterned master carrier for magnetic transfer, manufacturing method thereof, magnetic transfer method, recording medium, and magnetic recording and reproduction apparatus

A signal such as a servo tracking signal is recorded on a flexible slave medium by magnetic transfer. When forming the flexible slave medium of a magnetic strip in a continuous length, the signal is recorded on the magnetic strip by patterned master magnetic transfer prior to or simultaneously with shaping the magnetic strip into a desired shape.

Method of magnetic transfer to flexible medium

A master carrier for magnetic transfer is equipped with a substrate having a land/groove pattern. The land/groove pattern is formed from a magnetic material and corresponds to information that is transferred to a magnetic recording disk. Each land in the land/groove pattern has four round corners whose radius is from 1% through 47% of the width of a data track on the disk.

Master carrier for magnetic transfer

A master information carrier for magnetic transfer to an in-plane magnetic recording medium includes a base sheet having an irregularity pattern representing information to be transferred to an in-plane magnetic recording medium and a magnetic layer formed along the irregularity pattern. The thickness daof the magnetic layer on the upper surface of a protruding portion of the irregularity pattern and the thickness daof the magnetic layer on each of the side surfaces of the protruding portion satisfy the following condition,0.05&#x3c;21&#x2266;1.3.

Master information carrier for magnetic transfer and magnetic transfer method

An accurate magnetic transfer to a high-density slave medium having two magnetic layers and utilizing antiferromagnetic coupling is performed. By applying a first magnetic field that causes both the first and second magnetic layers of the magnetic layer of a slave medium to reach saturation magnetization unidirectionally along the circumferential direction of the track, the first and second magnetic layers are magnetized uniformly in the same direction as the first magnetic field. Then, a second magnetic field that inverts the magnetization of the first magnetic layer and has no effect on the magnetization of the second magnetic layer is applied in the opposite direction, whereby only the magnetization direction of the first magnetic layer is inverted in the direction of the second magnetic field. Thereby, a favorable initial magnetization state in which the magnetization directions of the first and second magnetic layers are oriented antiparallel can be obtained.

Magnetic transfer method for a high-density magnetic recording medium

A master carrier for magnetic transfer is equipped with a substrate with a land/groove pattern of lands and grooves, and a magnetic layer formed on the land/groove pattern. The adhesion between the substrate and the magnetic layer is 1.2&#xd7;10N/mor greater. A first oxygen concentration Dat the magnetic layer formed on the land is reduced gradually toward the direction of the depth of the substrate and is greater than a second oxygen concentration Dat the magnetic layer formed on the groove.

A master information carrier for magnetic transfer includes a base sheet which is formed of a magnetic material. The master information carrier is provided with an irregularity pattern representing information to be transferred to a magnetic recording medium and a magnetic layer formed along the irregularity pattern. The saturation magnetization Mm of the magnetic layer and the saturation magnetization Ms of the base sheet satisfy the condition1.0&#x3c;&#x3c;100.

A method of performing an accurate magnetic transfer to a high-density slave medium having two magnetic layers and utilizing antiferromagnetic coupling. The magnetic layer, which has been initially magnetized in advance, of a magnetic recording medium is conjoined with the data bearing surface of a master medium. A transfer magnetic field is applied to the conjoined body in the circumferential direction of the track of the first magnetic layer in the direction opposite the initial magnetization direction of the second magnetic layer. At this time, the thickness of the magnetic layer of the master medium, the permeability (material) of the magnetic layer, the form of the patterned magnetic layer, the separation distance between the master medium and the magnetic recording medium, etc., may be controlled so that the magnetic field of the transfer magnetic field does not effect the magnetization state of the first magnetic layer.

A master information carrier for magnetic transfer includes a substrate having an irregularity pattern representing information to be transferred to a slave medium and a magnetic layer formed on the irregularity pattern on the substrate. The depth d of the recessed portions of the irregularity pattern and the thickness t of the magnetic layer formed on the recessed portions satisfy formula &#x2212;0.004&#x2266;(t&#x2212;d)/d&#x2266;0.1. At the same time, the magnetic layer formed on the protruding portion of the irregularity pattern and the magnetic layer formed on the recessed portions of the irregularity pattern are connected with each other.

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Kanagawa, Japan

Tadashi Yasunaga