Fuji Photo Film Company, Limited

Fujifilm Corporation

Kazuhiro Niitsuma

Masakazu Nishikawa

Tadashi Yasunaga

Akito Kamatani

Kazunori Komatsu

Satoru Hayakawa

Toshio Kawamata

Toshihiro Usa

Yasushi Endo

Seiji Kasahara

Masaya Kojima

Kazuo Hiraguchi

Ryosuke Ogura

Makoto Nagao

Hitoshi Noguchi

Naoto Fujiwara

Tsuneo Inui

A master carrier for magnetic transfer, has: a support having an information writing region where a projection transfer pattern having a first projection is formed, the first projection corresponding to information to be transferred onto a magnetic recording medium; and a magnetic layer on the transfer pattern of the support,

Master carrier for magnetic transfer

When magnetically transferring information represented by a pattern of magnetic layer formed on a master information carrier to a disc-like slave medium, an initial DC magnetic field is applied to the slave medium to initially magnetize the slave medium in one direction of concentric recording tracks and a transfer magnetic field is applied to the slave medium in the direction opposite to the direction of the initial-magnetization with the initially-magnetized slave medium held in close contact with the master information carrier. At least one of applying the initial DC magnetic field and applying the transfer magnetic field is effected by applying the magnetic field while the slave medium is being rotated relatively to the magnetic field and stopping the rotation of the slave medium after the intensity of the magnetic field is gradually reduced to not stronger than a predetermined value.

Method of magnetic transfer and stopping slave medium rotation

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

By bring a master carrier and a slave medium into close contact with uniform force when executing magnetic transfer by applying transfer magnetic field in the state that the master carrier and slave medium is in confronted close contact and received within a holder, inferiority of transfer such as omission of signals is prevented and quality of transfer signals is enhanced. The magnetic transfer apparatus executes magnetic transfer by applying transfer magnetic field by means of a magnetic field applying apparatusafter a master carrierbearing transfer information and a slave mediumto be transferred are brought into confronted close contact and received within a holder, wherein said holderhas a substantially circular shape and in particular, the circularity of holder is not less than 98%, wherein the flexural rigidity=Ed/12 determined by Young's modulus E and thickness d of the holder is in the range of 0.1&#x2dc;30 kN&#xb7;mwhen the width of close contact area between the slave medium and master carrier is defined as 1 m, and wherein the practical thickness of the holder is not less than 3 mm and not more than 15 mm.

Magnetic transfer apparatus

The master carrier for magnetic transfer of the invention comprises a support and a magnetic layer formed on the surface of the support, wherein an uneven transfer pattern that corresponds to the information to be transferred to a magnetic recording medium is formed in the surface of the magnetic layer, and a relief is formed in the site where the transfer pattern is not formed.

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.

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

By bring a master carrier and a slave medium into close contact with uniform force when executing magnetic transfer by applying transfer magnetic field in the state that the master carrier and slave medium is in confronted close contact and received within a holder, inferiority of transfer such as omission of signals is prevented and quality of transfer signals is enhanced. The magnetic transfer apparatus executes magnetic transfer by applying transfer magnetic field by means of a magnetic field applying apparatusafter a master carrierbearing transfer information and a slave mediumto be transferred are brought into confronted close contact and received within a holderwherein said holderhas a substantially circular shape and in particular, the circularity of holder is not less than 98%, wherein the flexural rigidity=Ed/12 determined by Young's modulus E and thickness d of the holder is in the range of 0.1&#x2dc;30 kN&#xb7;mwhen the width of close contact area between the slave medium and master carrier is defined as 1 m, and wherein the practical thickness of the holder is not less than 3 mm and not more than 15 mm.

The present invention enables to execute accurate magnetic transfer without signal omission and the like, by bringing a master carrier which bore transfer information and a slave medium to undergo transfer into close contact with each other uniformly and without a gap when they are received in a holder and brought into confronted close contact with each other. In a magnetic transfer apparatus for executing magnetic transfer by applying magnetic field for transfer generated by a magnetic field applying apparatus after master carrierswhich bore transfer information and a slave mediumto undergo transfer are brought into confronted close contact with each other and received in a holder, materialshaving elastic characteristic are interposed between the holderand master carriers, thereby allowing microdeformation of master carriersto enhance the close contact capability with the slave medium.

A magnetic disk cartridge for use in a disk drive having both a slot and a guide portion. The magnetic disk cartridge comprises a generally disk-shaped housing in which a magnetic disk is rotatably housed, and protrusions. The protrusions are formed on the main surface of the housing and are used for positioning the magnetic disk cartridge in a direction capable of recording and reproduction in cooperation with the guide portion of the disk drive when the magnetic disk cartridge is loaded in the disk drive.

Magnetic disk cartridge

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.

Master information carrier for magnetic transfer

By bring a master carrier and a slave medium into close contact with uniform force when executing magnetic transfer by applying transfer magnetic field in the state that the master carrier and slave medium is in confronted close contact and received within a holder, inferiority of transfer such as omission of signals is prevented and quality of transfer signals is enhanced. The magnetic transfer apparatus executes magnetic transfer by applying transfer magnetic field by means of a magnetic field applying apparatusafter a master carrierbearing transfer information and a slave mediumto be transferred are brought into confronted close contact and received within a holder, wherein said holderhas a substantially circular shape and in particular, the circularity of holder is not less than 98%, wherein the flexural rigidity=Ed/12 determined by Young's modulus E and thickness d of the holder is in the range of 0.1&#x2dc;30 kN&#xb7;mwhen the width of close contact area between the slave medium and master carrier is defined as 1m, and wherein the practical thickness of the holder is not less than 3 mm and not more than 15 mm.

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Kanagawa-ken, Japan

Kazuhiro Niitsuma