Fujitsu Corporation

Toshiba Storage Device Corporation

Sony Corporation

Sumio Kuroda

Ken Tamanoi

Koji Matsumoto

Kazuyuki Ozaki

Koichi Iida

Keiji Shono

Tsugito Maruyama

Hiroyuki Suzuki

Mineo Moribe

Motonobu Mihara

Kazuhiko Takaishi

Yasunobu Hashimoto

Yutaka Nakamura

Tomoyoshi Yamada

Shingo Hamaguchi

Hiroyuki Takemoto

Masanori Fukushi

A magnetic storage apparatus has a reproducing head to reproduce information from a perpendicular magnetic recording medium that is recorded with servo information, eccentricity correction data and read/write data. The apparatus further has a filter part to filter a reproduced output of the reproducing head by filtering the servo information which has a differentiated waveform by a non-differentiating characteristic and by filtering the eccentricity correction data and the read/write data which have rectangular waveforms by a differentiating characteristic, a demodulating part to demodulate the servo information, the eccentricity correction data and the read/write data that are filtered by the filter part, and a servo system to carry out a control process including an eccentricity control based on the servo information and the eccentricity correction data that are demodulated.

Eccentricity correction method, signal processing circuit, magnetic storage apparatus and perpendicular magnetic recording medium

A master-disk producing device produces a master disk with master-disk identification information added. A disk producing device produces a first disk with the master-disk identification information added, using the master disk with the master-disk identification information added. A first disk device obtains, after the first disk with the master-disk identification information added is mounted, first correction information from a correction-information storing device based on the master-disk identification information of the first disk.

Disk-device correcting system, information managing device, master-disk producing device, and master-disk producing method

A master is used for writing information to a magnetic recording disk by a magnetic transfer method. The recording disk includes a magnetic recording layer possessing vertical magnetic anisotropy. The master includes a servo zone corresponding part formed with a magnetic material pattern for recording servo information to the recording layer of the recording disk. The master also includes a user data zone corresponding part formed with a second magnetic material pattern for providing the recording layer of the recording disk with a dummy signal.

Magnetic transfer master and method of formatting magnetic recording medium

Servo demodulation is performed by appropriately compensating for demodulation errors caused by fluctuation of the replayed signal amplitude of a phase servo pattern. A servo demodulating circuit comprises single waveform sampling means for reading into a register a single waveform of a servo burst signal included in a phase servo signal based on a sampling clock synchronized by clock synchronization means, single waveform digitizing means for calculating an amplitude value of the single waveform of the servo burst signal from peak and bottom of the single waveform of the servo burst signal read into the register, and for standardizing a value of the register based on an amplitude value of the single waveform of the servo burst signal, and phase information calculation means for calculating phase information of the single waveform of the servo burst signal based on the value of the register standardized by the waveform digitizing means.

Servo demodulating circuit and method

When copying servo information from an electro-magnetic field copy master to a vertical storage medium, the magnetization direction of the vertical storage medium is made to the direction the reverse of an external electro-magnetic field applied to the vertical storage medium and the electro-magnetic field copymaster, the vertical storage medium is closely touched on the electromagnetic field copy master provided with a substrate which has concavity/convexity corresponding to the servo information and at least the convex part of which of the concavity/convexity is made of a softly magnetic material and a conductor installed in the concave part of the substrate and an external electro-magnetic field stronger than the coercive field strength of the vertical storage medium is instantaneously applied to the vertical storage medium and the electromagnetic field copy master.

Manufacturing method of recording medium, electric/magnetic field copy master and electric/magnetic field copying device

A magnetic transferring apparatus allows attachment of a first magnet to a first holder. A second magnet is attached to a second holder. The first and second holders are located in a space between first and second magnets. A magnetic disk and a master member are located in a space between the first and second holders. The magnetic attraction is generated between the first and second magnets. The magnetic attraction serves to bring the first and second holders closer to each other, so that magnetic pieces of the master member is brought in a close contact with the magnetic disk between the first and second holders. The magnetic flux runs between the first and second based on the contact between the magnetic pieces and the magnetic disk. A servo pattern can in this manner be established in the magnetic disk.

Magnetic transferring apparatus

The present invention provides a magnetic recording unit, including: a magnetic head; a magnetic recording medium having a servo pattern for adjusting a position of the magnetic head; a frequency detecting element for detecting a frequency in the servo pattern on a track corresponding to the position in a radial direction of the magnetic recording medium, on the basis of a reproduction signal obtained by reading the servo pattern with the magnetic head; a storage element for storing in advance information on predetermined frequencies corresponding to the positions of tracks of the magnetic recording medium; a tracking element for comparing the frequency detected on the track by the frequency detection element and the information on the frequency corresponding to the same track, the information being stored in the storage element, and for generating a signal for adjusting the position of the magnetic head, the signal being generated on the basis of a difference between the frequencies.

Magnetic recording unit and magnetic recording medium

The magnetic recording and reproducing apparatus reads a transfer clock synchronized with servo information and records a write-once clock pattern in a state where 0 is set as a delay time of the delay deviceand 1 is set as the dividing ratio of the frequency divider. The apparatus corrects the delay time according to the output of the phase comparatorwhich changes on the basis of the phase difference and rewrites a write-once clock pattern. Rotation of the magnetic disk, detection of the phase difference and correction of the delay time are repeatedly preformed until no change occurs in the output of the phase comparator. After the output stops changing, preformat information patterns excluding the servo information pattern are recorded as fine patterns by changing the dividing ratio of the frequency dividerto multiply the frequency.

Preformat method for magnetic recording medium, magnetic recording medium, and magnetic recording and reproducing apparatus

The present invention provides an optical disk comprising: at least a rewritable region and a read-only data region, wherein the rewritable region includes a plurality of groove tracks and a plurality of land tracks, the read-only data region includes a plurality of groove tracks and a plurality of land tracks, read-only data comprising control data are written as concavo-convex pits to the groove tracks and/or the land tracks in the read-only data region, and the width of each groove in the read-only data region is smaller than that of each groove in the rewritable region. According to the first optical disk of the present invention, the area of rewritable regions for users can be ensured as broadly as possible failing to deteriorate the high-speed performance of the system.

Optical disk

A master medium for magnetic transfer includes a substrate having a concave portion formed in its surface corresponding to a pattern of recorded information to be transferred; a first perpendicular ferromagnetic layer deposited in the concave portion; and a second perpendicular ferromagnetic layer layered on the substrate surface and the first perpendicular ferromagnetic layer surface. The substrate surface and the first perpendicular ferromagnetic layer surface are flattened to form a single flat surface. In the master medium for magnetic transfer, a magnetic field change in a direction parallel to the substrate surface at a magnetization boundary of the first perpendicular ferromagnetic layer is steep. Since the influence of the change of an external magnetic field is reduced, it is possible to perform accurate transfer from the master medium for magnetic transfer to a slave medium for magnetic recording.

Master medium for magnetic transfer, magnetic transferring and recording method, slave medium for magnetic recording, and method for producing a master medium for magnetic transfer

A magnetic recording medium having a magnetic layer includes a plurality of tracks formed on the magnetic layer. The tracks have information magnetically recorded thereon. A magnetization change area for tracking control is formed on the magnetic layer adjacent to and along a length of each of the tracks. The magnetization change area has magnetic flux which changes along the length of the tracks.

Magnetic recording medium having tracking control area formed adjacent data tracks

An optical recording medium driving apparatus which can obtain a tracking error signal necessary for an accurate track count. An optical recording medium driving apparatus for recording and/or reproducing data in/from an optical recording medium, where information can be recorded in plural tracks formed by land portions and groove portions provided between the land portions, based on a light emitted to the tracks. The apparatus includes a detector for detecting a position of the emitted light, a peak-hold circuit for holding a peak of a position detected signal outputted from the detector so as to output the position detected signal, a bottom-hold circuit for holding a bottom of the position detected signal so as to output the position detected signal, and a switching circuit for switching signals based on the output signals from the peak-hold circuit and bottom-hold circuit so as to output either signal.

Optical recording medium driving apparatus

A magneto-optical recording medium capable of perfectly masking a mark adjacent to a mark to be reproduced thereby improvng reproduction output. The magneto-optical recording medium includes a transparent substrate, a magnetic reproducing layer laminated on the transparent substrate, a nonmagnetic intermediate layer laminated on the magnetic reproducing layer, and a magnetic recording layer laminated on the nonmagnetic intermediate layer. The reproducing layer has an easy direction of magnetization in a plane at room temperature, and has an easy direction of magnetization perpendicular to a film surface at a given temperature or higher. The nonmagnetic intermediate layer is thin enough to allow magnetostatic bond between the recording layer and the reproducing layer at the given temperature or higher. Instead of the nonmagnetic intermediate layer, a magnetic intermediate layer having an easy direction of magnetization in a plane from room temperature to its Curie temperature may be interposed between the reproducing layer and the recording layer.

Magneto-optical recording medium and reproducing method for information recorded on the medium

A magneto-optical recording medium capable of perfectly masking a mark adjacent to a mark to be reproduced thereby improving a reproduction output. The magneto-optical recording medium includes a transparent substrate, a magnetic reproducing layer laminated on the transparent substrate, a nonmagnetic intermediate layer laminated on the magnetic reproducing layer, and a magnetic recording layer laminated on the nonmagnetic intermediate layer. The reproducing layer has an easy direction of magnetization in a plane at room temperature, and has an easy direction of magnetization perpendicular to a film surface at a given temperature or higher. The nonmagnetic intermediate layer is thin enough to allow magnetostatic bond between the recording layer and the reproducing layer at the given temperature or higher. Instead of the nonmagnetic intermediate layer, a magnetic intermediate layer having an easy direction of magnetization in a plane from room temperature to its Curie temperature may be interposed between the reproducing layer and the recording layer.

Growing community of inventors

Kawasaki, Japan

Sumio Kuroda