Hitachi, Ltd.

Hajime Aoi

Nobumasa Nishiyama

Yasuhide Ouchi

Takashi Tamura

Makoto Koizumi

Toshiaki Tsuyoshi

Yosuke Seo

Yoshihisa Kamo

Yoshibumi Matsuda

Hitoshi Kakuta

Takuji Ogawa

Kazuhisa Shiraishi

Fumio Kugiya

Yasuhiro Katoh

Reijiro Tsuchiya

Makoto Saito

Hiroshi Fukui

Yutaka Sugita

Yoshihiro Shiroishi

Atsushi Kikugawa

Eiichi Murakami

Yoshihisa Fujisaki

Shinji Narishige

Shigeyuki Hosoki

Ryo Imura

Yokuo Saitoh

Naoki Sato

Fumihiko Uchida

Kiyokazu Nakagawa

Hirotsugu Fukuoka

Masakazu Ichikawa

Shigeo Kato

Sumiko Fujisaki

Makoto Aihara

Kazuyoshi Nakabayashi

Hiroyuki Suzuki

Hisashi Takano

Masaaki Futamoto

Moriaki Fuyama

Yoshito Tsunoda

Hiromichi Fujisawa

Masaaki Hayashi

Hideki Sawaguchi

Mikio Suzuki

Kazuetsu Yoshida

Kyo Akagi

Takeshi Nakao

Kanji Kawakami

Yoshinori Miyamura

Masanobu Hanazono

Kazuo Nakagoshi

Sadao Hishiyama

Tomoyuki Ohno

Katsuya Mitsuoka

Takayuki Munemoto

Tokuho Takagaki

Masanori Tanabe

Jun Naruse

Makoto Saitou

Noriaki Hatanaka

Makoto Saitoh

Masayuki Katsumoto

Yoshiyuki Hirano

Susumu Funamoto

Yasushi Kitazaki

Yoshikazu Tsuji

Minoru Enomoto

Tetsuji Kameoka

Takamasa Uchiyama

Sakae Ohta

Shyuichi Kojima

Masaya Tanaka

Noboru Kunimi

Yoshihasa Kamo

An array disk subsystem including a command selector for separating a signal from a host into a data item and a command, a data dividing unit for subdividing the data item, an ECC generator for producing an ECC for each of the obtained subdata items, a group of data disks for respectively storing thereon the subdata items and the ECCs, a command interpreting unit for interpreting the command, an I/O counter for counting I/O commands in the command, a backup processor for requesting a backup command based on count information of the I/O counter, and a backup unit responsive to the backup command for sequentially reading the subdata items and the ECCs from the data disks to record therein the subdata items and the ECCs.

Array disk subsystem

In a magnetic recording drive having a plurality of magnetic heads each employing a magnetoresistive sensor for the purpose of averaging the time required for sense currents to be caused to flow through the respective magnetoresistive sensors to shorten the longest reproducing time and to suppress the degradation of the characteristics due to the electromigration, thereby improving the reliability of the magnetic recording drive, the magnetic recording drive includes circuits for averaging the useful life depending on the currents caused to flow through the respective magnetoresistive sensors among the plurality of magnetic heads, whereby the time required for the sense current to be caused to flow through one MR reproducing head is greatly shortened. Therefore, the levels of outputs of the MR reproducing heads can be increased without reduction of the reliability and thus the reliability of the magnetic recording drive can be improved.

Magnetic recording drive having arrangement for averaging useful life of

Magnetic recording drive

A fast data transfer system capable of eliminating the need to extremely increase the necessary transmission frequency band for the high-density recording and fast revolution rate of data recording and reproducing system has a recording and reproduced signal processor including an encoder/decoder, a disk enclosure including a parallel-to-serial converter, a record head, and a serial-to-parallel converter, and a transmission cable, and makes recording parallel data transfer from the encoder/decoder to a recording amplifier by shifting the phases of a plurality of recording signals and reproduced parallel data from the serial-to-parallel converter to the encoder/decoder by shifting the phases of a plurality of reproduced signals. The necessary transmission frequency on the transmission cable can be reduced by this parallel data transfer on the transmission cable. In addition, a record timing correction circuit can be provided on a parallel data transfer path.

Method and apparatus for fast transfer of data in recording and

A fine-fabrication method of solid surfaces relates to a new surface fabrication method allows a solid-device surface to be fabricated at an atomic scale so as to produce an ultra-fine device or a device for recording information at an ultra-high density. A probe is installed with a tip thereof facing to the surface of a specimen to undergo fabrication. A voltage for forming an electric field is applied between the probe and the specimen. The electric field is large enough to field-evaporate atoms constituting the specimen or the probe; the electric field field-evaporates atoms constituting the specimen, removing them from the surface of the specimen; and as another alternative, the electric field field-evaporates atoms constituting the probe, depositing them on the surface of the specimen. Further, in another surface atom fabrication method, while the surface of a specimen is observed at an atomic scale using a surface observation technique by means of a scanning tunnelling microscope, a pulsative voltage large enough for the field evaporation of atoms described above is applied between the probe and the specimen at any arbitrary desired positions on the surface of the specimen; and the pulsative voltage field-evaporates and, hence, eliminates atoms one by one from the surface of the specimen.

Surface atom fabrication method and apparatus

A magnetic disc apparatus has a large recording density of 120 megabits per square inch or more, and defines a relationship among a pole thickness (Pt) of thin-film magnetic heads disposed in the magnetic disc apparatus, and a saturation flux density (Bs) of cores of the heads and a recording wavelength (.lambda.) for the thin film magnetic discs have a coercivity of 1800 Oe or more, wherein a levitation space between the head and the disc is 0.15 .mu.m or less.

Large capacity magnetic disc apparatus with a particular relationship

Magnetic recording drive having arrangements for average useful life of

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

A waveform equalizer for processing a signal read by a magnetic head from a magnetic written medium includes a slimming circuit which, in turn, has a first delay unit for delaying the read signal, a first attenuator connected in parallel with the first delay unit, a first differentiating circuit for receiving the output from the first delay unit and the output from the first attenuator, and a resistor connected to a first delay unit side input of the first differential circuit; and a pseudo-peak elimination circuit connected in series with the slimming circuit and including a circuit for separating the from the read signal the read signal or a signal reverse in phase to the read signal, a second delay unit for delaying the separated signal, a second attenuator for attenuating the amplitude of the separated signal, and a second differential circuit for receiving the read signal and the separated, delayed and attenuated signal.

Digital magnetic writing and reading 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

The time interval/amplitude level difference between sequential peaks in waveforms of first reproducing signals from a recording medium is detected and stored in a storage. The time interval/amplitude level difference between peaks in a waveform of a second reproducing signal from the recording medium is detected and compared with the time interval/amplitude level difference stored in the storage to thereby perform peak detection in the waveforms thereof. An original bit train of the first reproducing signal corresponding to a maximum-likelihood waveform selected among the waveforms of the first reproducing signals is given as a standardized signal. Data are provided to represent the time interval/amplitude level difference between the sequential peaks in the waveforms of the reproducing signals in a range of electromagnetic signal interference on the recording medium.

Peak detection method and apparatus therefor

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

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Tachikawa, Japan

Hajime Aoi