Hitachi, Ltd.

Hitachi Global Storage Technologies Japan, Ltd.

Yosuke Seo

Yoshihisa Kamo

Hitoshi Kakuta

Atsushi Tanaka

Hajime Aoi

Takashi Tamura

Kyo Akagi

Toshiaki Tsuyoshi

Yasuhide Ouchi

Yoshiyuki Hirano

Hisashi Takano

Makoto Saito

Masaaki Futamoto

Norio Ohta

Yutaka Sugita

Yoshito Tsunoda

Hiromichi Fujisawa

Yoshibumi Matsuda

Yoshio Kawamura

Mikio Suzuki

Takeshi Nakao

Yoshinori Miyamura

Fumio Kugiya

Hirotsugu Fukuoka

Takayuki Munemoto

Tokuho Takagaki

Youichi Kawakubo

Shigenori Okamine

Makoto Aihara

Kazuhisa Shishida

Toyoji Okuwaki

Makoto Horisaki

Katsuhiko Kato

Kazuyoshi Nakabayashi

Takahiro Inoue

Youichi Kusagaya

With respect to the disk drives provided power from a single power source in a disk drive system, start up power is first supplied to a first start-up group of the disks, preferably comprising all of the master disks, with the size of the group being selected so that the required current does not exceed the capacity of the power source. When the disk drives of the first group have substantially reached steady state, start-up is conducted with respect to a second start-up group of the disk drives so that the current required during start-up for the second group and the current required for steady state drive of the first start-up group does not exceed the capacity of the power source. With respect to each start-up group, the number of disk drives is the maximum integer value and decreases or remains the same with respect to subsequent start-up groups. When simultaneously transferring subdivided data in parallel to all of the disk drives of a parity group, respectively, seek operations in such a system are prevented from occurring simultaneously by offsetting the indices on the disks, by varying the seek operation start timing or by varying the head addresses for the start of reading and writing, all within one revolution, but the seek operations are ended at the same time, to reduce peak current requirements of the power source.

Disk system and power-on sequence for the same

In order to achieve narrow track pitch by measuring, storing and compensating common average values for repeatable runout components between adjacent tracks in a head positioning control system for a magnetic disk drive, a compensation signal is calculated for the average value of the repeatable runout of each servo sector of at least two tracks of servo information reproduced from a magnetic disk, on the basis of an inverse function of the sensitivity characteristics of the tracking control system. The compensation signal is stored, and thereafter used for compensating the servo signal.

Magnetic disk drive for compensating repeatable runout error

Disclosed are a method and a device that exhibit better performance against factors inhibiting an increase in track density than the current system. A servo pattern is constituted of a plurality of patterns arranged on both sides of the center lines of tracks, the patterns on one side of the center line being shifted in the track direction from the patterns on the other side along the center line, and patterns A and B are each constituted of two types of phase patterns arranged in the track-width direction, which are patterns and and patterns and , respectively. The positional signal of a magnetic head is decoded by determining a sinusoidal function, which roughly agrees with the waveform of the reproduced signal of the servo pattern, based on the information on the frequency of the reproduced signal which has been stored in advance.

Magnetic disk drive with servo signal decoder using amplitude detection and phase detection system

Disk system with activation control of disk drive motors

A method for recording servo patterns in a magnetic disk drive and a magnetic disk drive for executing such a method are provided. A magnetic disk on which a clock signal has been recorded in at least a part thereof is mounted into the magnetic disk drive. The clock signal is read out from the magnetic disk by using a data recording/reproducing magnetic head. A servo pattern is further recorded by using the recording/reproducing magnetic head on the basis of the read-out clock signal.

Method for writing servo signals onto a magnetic disk and magnetic disk

A file system including an input/output unit for inputting data from and outputting data to an external system; a controller connected to the input/output unit for dividing the data into an optional number of parallel data; a management table for storing the number of divisions of the data; a head group for writing the divided parallel data into a storage medium at the same time; and a unit for reading the data from the storage medium while referring to information stored in management device.

Variable length data in a parallel disk array

A method and device of head positioning in an information recording/reading device in which a magnetic recording medium with data tracks for recording information thereon is provided and a magnetic head is positioned on the data track to record/read out the information, wherein a data signal is recorded in the data recording layer of said recording medium, a servo signal is recorded in the servo signal recording layer located below said data signal recording layer, said data signal is read out using a data magnetic head whereas said servo signal is read out using a servo magnetic head, and the frequency of said servo signal is within the range of the gap-null frequency of said data magnetic head whereas the frequency of said data signal is within the range of the gap-null frequency of said servo magnetic head, and said magnetic head is positioned on the data track on the basis of said servo signal. A method and device of head positioning in an information recording/reading device in which a magnetic recording medium with data tracks for recording information thereon is provided and a magnetic head is positioned on the data track to record/read out the information, wherein the data tracks are discrete tracks in which adjacent data tracks are separated by a groove located therebetween, a data signal is recorded on the data track of said recording medium, a servo signal is recorded on the servo tracks of grooves between said adjacent data tracks, and said magnetic head is positioned on the data track on the basis of said servo signal.

Method of head positioning and magnetic recording disk drive using the

In the information recording disk, the positioning signal of the information convertor is provided permanently, as a change in shape or material, to the front and reverse surfaces of the disk substrate and their eccentric distances from the center position is made to be smaller than half the repeating unit length of the positioning signal of the information convertor in the radial direction. The start position of the positioning signal in the circumferential direction is preferably made to be coincident on the front and reverse surfaces of the disk substrate within 10 .mu.m. The position reference for aligning the position in the radial direction or the position reference for aligning the rotation angle position in the circumferential direction is preferably disposed on the inner diameter portion or outer diameter portion of the disk substrate, respectively, and these position references can be accomplished by disposing at least one notch on the inner or outer peripheral edge portion of the disk substrate.

Information recording disk, its production method and recording apparatus

An error correction circuit which includes a specification circuit for specifying erroneous portions in a first data set reproduced from a recording medium, a register for storing the reproduced first data set including the erroneous portions thus specified and a reproducing circuit responsive to the reproduced first data set for reproducing again the first data set from the recording medium to obtain retry data, when there exist erroneous portions in the reproduced first data set stored in the register. The correction circuit also includes a data replace circuit, connected to receive the retry data, for replacing information at the specified erroneous portions in the reproduced first data set stored in the register by information at corresponding portions in the retry data.

Method for error correction and circuit for realizing same

A constant-density type of magnetic disk apparatus is made up of a plurality of magnetic disks, wherein at least one of the surfaces of the magnetic disks is a servo face divided into a plurality of zones in the radial direction of the disks. A magnetic disk used in this apparatus and a servo-writing device for making this magnetic disk are also disclosed. In the magnetic disk apparatus and the magnetic disk, servo information regions and clock information regions are alternately provided on the servo face in the circumferential direction of the disks. The servo information regions are arranged radially with respect to the rotation center of the disks and each of the clock information regions includes a plurality of magnetic transitions representative of clocks, the number of which is different for each of the divided zones. A servo PLL circuit is provided to generate a servo clock signal on the basis of the signal reproduced from each of the servo information regions, and a write PLL is also provided to generate a write clock signal on the basis of the signal reproduced from each of the clock information regions. Also disclosed is a disk for use in a constant density-recording type magnetic disk apparatus, wherein a dummy track is provided along a zone boundary on the data face embedded with servo patterns of the disk.

Magnetic disk apparatus of constant-density recording type, magnetic

A disk drive unit is disclosed, which comprises a recording medium having more than two disk-shaped recording faces disposed on each other with an interval; information tracks disposed along the periphery on the more than two recording faces and servo signal fields on the recording faces, in the peripheral direction for different recording faces; more than two heads reading out servo information from the servo signal fields on the more than two recording faces; head moving means for moving the heads in the radial direction of the recording faces, linked with each other; means for obtaining position signals on the recording faces at different points of time for different heads on the basis of the servo signals; means for obtaining information on the relative velocity of the heads to the recording faces from the position signals at different points of time for different recording faces, and control means for effecting the velocity control by means of the head moving means on the basis of the information on the relative velocity.

High speed seek sector servo magnetic disk drive unit

Growing community of inventors

Sagamihara, Japan

Yosuke Seo