Fujitsu Corporation

Tatsuro Sasamoto

Susumu Yoshida

Koichi Aikawa

Akihide Jinzenji

Kazunori Mori

Kazuo Nishimura

Hideaki Tanaka

Keiji Aruga

Isamu Tomita

Hiroaki Etoh

Tatsuhiko Kosugi

Masamichi Suzuki

Hideyuki Watanabe

Tomoo Sukagawa

Masakazu Hirano

Yoshiaki Koizumi

Yoshihiro Nakao

Yasuyoshi Asao

There is provided a technique capable of eliminating the need to create data for compensating the displacement of a servo pattern occurring at the time of writing the servo pattern using an amplitude method and thereby of significantly reducing the production time of a disk medium. A servo pattern writing apparatus that uses a write head to write a servo pattern on a recording medium according to an amplitude method, comprises: a position sensor that detects the displacement amount of the write head with respect to its reference position in the track crossing direction; and a delay amount adjustment circuit that writes a servo pattern in correspondence with a servo pattern write phase amount which is set for compensating the displacement amount detected by the position sensor at the time of demodulation of the servo pattern.

Servo pattern writing apparatus, servo pattern writing method, servo pattern reading apparatus, and servo pattern reading method

A disk device comprises a disk having predetermined information sectors recorded at a constant interval; a head scanning the disk; and a disturbance-compensation unit obtaining an amount of a disturbance based on a time-interval measurement in reading the predetermined information sectors so as to compensate a position of the head according to the amount of the disturbance.

Disk device conducting a disturbance compensation based on a time-interval measurement in reading servo sectors recorded on a disk

A disk drive unit includes acceleration sensors mounted thereon. A sequence for calculating an amount by which a head actuator is adjusted during recording and readout operations is changed based on an output from the acceleration sensors.

Disk drive unit and control method for same

A magnetic disk unit has two actuators each rotating on a common rotary shaft. The two actuators are driven by a voice coil motor. The voice coil motor comprises: a magnetic circuit comprising a magnet provided for the two actuators on a common basis and two yokes, which are associated with the two actuators, respectively, said two yokes being disposed at both sides between which the magnet intervenes; and two coils provided for the two actuators, respectively.

Storage device

In a magnetic disk apparatus in which heads integrally having write heads and read heads are arranged correspondingly to data surfaces of plural media, servo information including phase servo patterns is written discretely in a track direction onto the data surfaces of the plural media. For this reason, at first, displacement amounts of the read heads with respect to the write heads are measured in each head and each cylinder position of the media. Next, phases of the phase servo patterns are adjusted so that relative displacement amounts between the reads heads are eliminated in each head and each cylinder position of the media, and the phase servo patterns are written.

Servo information writing method and storage device

Disclosed is a calibration method for an acceleration sensor in a storage device for calibrating and a storage device, an enclosure for calibrating the acceleration sensor for compensating a vibration of an enclosure in a state of its being mounted in a storage drive. The calibration method and mode comprises a step of exciting a actuator of the drive by flowing a drive current having a predetermined current value, a step of calculating the acceleration of the enclosure of the drive from the predetermined current value and a mechanical transfer function of the storage device, a step of detecting a measured value of the acceleration sensor, and a step of calculating a sensitivity of the acceleration sensor from the calculated acceleration and from the detected measured value. The acceleration sensor is calibrated in the state of its being mounted in the disk drive, and hence the sensitivity can be precisely calibrated.

Calibration method for acceleration sensor in storage device and storage device

A disk device performs feedforward servo control for moving a head to a target track. The disk device includes a calibrating portion for updating feedforward information, for moving the head, into information dedicated to the specific disk device; and a feedforward information storing portion for storing the feedforward information.

Disk device and disk device calibrating method

Disclosed are a servo pattern writing method for magnetic disk drives making it possible to write a high-density and easily controllable servo pattern with high producibility, and a magnetic disk drive in which a servo pattern is written according to the method. The servo pattern writing method for magnetic disk drives in which a servo pattern is written on a plurality of surfaces in a magnetic disk drive having the plurality of surfaces comprises a step of writing a master servo pattern on a master surface that is one of the plurality of surfaces, and a step of writing a servo pattern on the surfaces other than the master surface while performing positioning on the basis of the master servo pattern. The master servo pattern contains a pattern identical to the servo pattern to be written on the surfaces other than the master surface. The master servo pattern is written before the master surface is incorporated in a main unit of the magnetic disk drive. Part of the master servo pattern other than the pattern identical to the servo pattern is deleted after the servo pattern is written on the surfaces other than the master surface.

Servo pattern writing method for magnetic disk drives, and magnetic disk

The present invention relates to an information recording medium for a disk drive having improved recording efficiency. The information recording medium is provided with discrete servo and data areas, with servo information being recorded in the servo areas. Cylinder information included in one or more servo areas is used to locate particular data areas on a disk. In the present invention at least partial cylinder information in one servo area is used to locate more than one data area by dividing the cylinder information into different servo areas, or using the cylinder information in one servo area to locate a data area associated with another servo area. By recording the divided cylinder information in respective ones of the servo areas provided on a given cylinder on the disk, less disk space is needed for cylinder information, so the size of the data areas can be increased and recording efficiency can be improved.

Information recording medium having divided cylinder address storage

A storage device includes a predetermined number of disks on which servo information is recorded, and a predetermined number of heads. The heads are positioned on target cylinders on the basis of the servo information read from the disks through the heads, so that information recording/reproducing can be performed. The disks include outer guard band areas located further out than data areas and inner guard band areas located further in than the data area. Analysis information concerning disk surfaces are recorded on the outer guard band areas. Each of the outer guard band areas is segmented into first and second outer guard band areas in a radial direction. The analysis information is recorded on the first outer guard band area. The servo information for an off-track correction is recorded on the second outer guard band area.

Method for reliably positioning a head in a disk drive to a guard band

A disk apparatus in which a seek operation of one of a plurality of heads to a target position on one of a plurality of recording disks is performed by using location data on the one of the recording disks, includes a memory unit in which at least defect location data is stored, the defect location data indicating a location of a defect on the recording disks. A defect location determining unit determines a seek path of one of the heads from a present position to the target position prior to performing the seek operation, and detects whether the defect location is included in the seek path. A seek control unit performs the seek operation of the one of the heads by using the location data on the one of the recording disks, and inhibits using the location data at the defect location when the defect location determining unit detects that the defect location is included in the seek path.

Disk apparatus for controlling a seek operation of a read/write head to

There is used a disk medium in which tracks are divided into a plurality of zones in the radial direction and information is read and written with a constant linear density by using a clock signal of a different frequency every zone. A drive unit forms a dead space corresponding to at least one track at a zone boundary of the disk medium and reads or writes the information. In the case where it is judged that the head passes through the zone boundary by the seeking operation to the cylinder address position instructed from an upper apparatus, the cylinder address instructed from the upper apparatus is corrected on the basis of the number of boundary passing times and the seeking operation is performed.

Magnetic disk apparatus, recording and accessing method for performing

Magnetic disk apparatus, recording medium, and accessing method for

A method of controlling start-up of a sensorless spindle motor used in a disk apparatus reduces time spent on start-up of a spindle motor with high reliability. The motor is used for rotating a disk on which information is recorded, and no sensor is provided in the motor for sensing an angular position of a rotor relative to a stator of the motor. The motor is operated at a steady rotational speed and is stopped by supplying a stop command. An aligning operation is performed immediately after the motor is stopped. The aligning operation is performed to rotate the rotor to a predetermined angular position relative to the stator of said motor. The motor is operated at a steady speed by a synchronization control when operation of the motor is started by supplying a start command.

Method of controlling a start-up of a motor used for a disk apparatus

In a disk medium, as servo patterns for offset detection, a pattern which is offset to the inner side, a pattern which is offset to the outer side, and a polarity pattern of a size exceeding a width of pattern as necessary are recorded in the track direction at specific cylinder positions of each data surface. In the case where only one of the read signals of the patterns which are offset to the inner side and outer side is obtained, the head is returned in such a direction as to eliminate the offset, and an offset measuring section measures the offset again. In this case, the offset measurement value is set to the total value of the head return amount and the last offset amount obtained from the read signals V1 and V2. When both of the two pattern read signals V1 and V2 are not obtained, the presence or absence of the read signal of the polarity pattern is judged. When the read signal of the polarity pattern exists, the head is offset to the side opposite to the polarity pattern by a predetermined amount and the offset is again measured. When the read signal of the polarity pattern doesn't exist, the head is offset by only the predetermined amount to the side on which the polarity pattern is not recorded and the offset is subsequently measured again.

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Kawasaki, Japan

Tatsuro Sasamoto