Hitachi, Ltd.

Hitachi Global Storage Technologies Japan, Ltd.

Hitachi Computer Peripherals Co., Ltd.

Katsuhiro Tsuneta

Hideaki Amano

Koji Kodama

Yuichi Koizumi

Tsuneo Hirose

Terumi Takashi

Takashi Yamaguchi

Akira Kojima

Yasunori Kaneda

Masahito Kobayashi

Motoyasu Tsunoda

Yukari Katayama

Hitoshi Ogawa

Shoichi Miyazawa

Eisaku Saiki

Hidehiko Numasato

Yosuke Hamada

Yoshikatsu Fujii

Tsuyoshi Arai

Katsumoto Onoyama

Haruhiko Hosokawa

Koichi A Ono

Toshiyuki Haruna

Yuji Yoshida

Hidekazu Honda

Akihiro Nakamura

Toshiaki Tsuyoshi

Akira Kurano

Kiyotaka Takahashi

Toshihisa Okazaki

Hiromu Hirai

Satoru Yamaura

Kazuyoshi Hanada

Kenji Nishimura

Akio Takatsuka

Toshio Matsushita

Masahiro Mitamura

Tetsuji Kameoka

Kazuhiko Satake

Takeo Iwai

Yoshinori Tuneda

Riichi Nakano

Kazuto Takahashi

Tadayuki Ichiba

Jin Hamada

An information storing device and an information processing device having a memory for registering a plurality of working modes at recording/reproduction and a switching circuit for selecting one of the plurality of working modes, which select the optimum working mode automatically or by an instruction of an operator according to power supply capacity of a device of higher rank to effect recording/reproduction.

Information storing device and method for controlling same to record/reproduce information by selecting one of working modes

The electromagnetic noise radiated from a magnetic disk system comprising two or more magnetic disk drives is reduced so as not to exceed a certain level although the electromagnetic noise from each magnetic disk drive is added up. This is achieved by setting a different operation clock frequency for each SCSI-ID so that the electromagnetic noise radiated from each magnetic disk drive has a different frequency band.

Adjusting clock frequency in a disk drive and a disk system using the same

The actual data recording area on a recording medium is expanded by reducing a gap area between blocks of data for compensating for a delay time of data conversion while recording and reproducing data in a data recording and reproducing device. Based on a servo sector signal, a data sector generator circuit generates a write data sector signal indicating a timing of data recording in a data recording area, and outputs the write data sector signal to a delay circuit and a selector having two input ports and one output port. The delay circuit generates a read data sector signal by delaying the write data sector signal by a certain period, and outputs the read data sector signal to the selector. The selector outputs the write data sector signal when a write mode signal is active, and outputs the read data sector signal when the write mode signal is inactive.

Method and device for recording and reproducing data

Information storing device and method for controlling same to record/reproduce information by selection one of working modes

An information storing device and an information processing device having a memory for registering a plurality of working modes at recording/reproduction and a switching circuit for selecting one of the plurality of working modes, which select the optimum working mode automatically or by an instruction of ah operator according to power supply capacity of a device of higher rank to effect recording/reproduction.

A sector servo type magnetic disk apparatus is provided with, in addition to servo signals, a sensor such as an accelerometer for detecting a state of a magnetic head or a support for the magnetic head at a period shorter than a sampling period of the servo signals. Since an accelerometer mounted on the magnetic head or the support for the magnetic head detects an acceleration, the control performance of a servo control system can be improved, such as reduction of generation of mechanism resonance vibrations of a carriage and improvement on detection precision of a speed signal.

Magnetic disk apparatus having an accelerometer for detecting acceleration in the positioning direction of the magnetic head

A magnetic disk recording and reproducing apparatus comprising a unit for inserting an error correcting code related to control information into said control information on data; a recording control unit for recording in a plurality of sectors formed by dividing the recording area of a magnetic disk, each sector having an ID area for recording said control information and a data area, provided adjacent to and behind said ID area, for recording said data; and a error correcting unit for correcting said control information of said ID area by said error correcting code before data is read from said data area corresponding to said ID area or data is recorded in said data area corresponding to said ID area.

Method and apparatus for recording and reproducing disk-type recording medium with dual head including reading head and writing head having offset cores

A disk type recording and reproducing apparatus includes a disk type recording medium having a plurality of tracks and having stored on each of the plurality of tracks a position signal indicating positions on the tracks; a drive section for rotating the disk type recording medium; a dual head separately incorporating a reading head for reading from the disk type recording medium and a writing head for writing into the disk type recording medium; a head drive section for moving the dual head; means for controlling the head drive section by a controlled variable in compliance with a position signal read from the disk type recording medium using an object track and the reading head; and memory means for storing quantity information used to correct the controlled variable of the means for controlling the head drive section. The means for controlling the head drive section, at least in a writing operation, obtains the controlled variable of the head drive section according to the position signal read from the disk type recording medium using the object track and the reading head and the quantity information stored in the memory means.

Information storing device and method for controlling same to

A magnetic disk device of embedded-servo type is capable of performing dummy operation for suppressing waveform degradation of signal reproduced by magnetic heads at a high speed with high reliability. When a waveform deformation occurs in a No.0 head, a controller changes over the No.0 head to a No.1 head operating normally, whereupon a cylinder portion for which dummy operation is to be performed is sought on the basis of the servo information supplied from the No.1 head. The cylinder portion destined for the dummy write operation contains servo information at timing positions that are the same for the individual magnetic heads. When passing of the No.1 head over the cylinder portion is confirmed, the No.1 head is changed over to the No.0 head for performing dummy write operation for suppressing the waveform deformation of the reproduce signal outputted from the No.0 head. Before the timing for succeeding information, the No.1 head is restored by issuing a head change command signal. Because the seek operation is realized exclusively by the magnetic head suffering no abnormality, the dummy write operation for preventing waveform deformation of the reproduced signal outputted from the No.0 head can be realized without fail.

Magnetic disk device with dummy write function

A disk type recording and reproducing apparatus includes a disk type recording medium, and a dual head including a reading head and a writing head. A center of the core of the reading head is shifted in the radial direction of the disk type recording medium relative to a center of the core of the writing head. The disk type recording medium has a plurality of recording tracks each having a plurality of sectors. Each of the sectors has an ID division provided ahead of a data division disposed in the circumferential direction of the disk type recording medium. The ID division has recorded therein identification information identifying the sector. A center line of the ID division is shifted in the radial direction of the disk type recording medium relative to a center line of the data division by a distance equal to a distance by which the center of the core of the reading head is shifted in the radial direction of the disk type recording medium relative to the center of the core of the writing head. The data division has identification information identifying the sector stored in a position ahead of data to be recorded and reproduced.

Method and apparatus for recording and reproducing disk-type recording

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Odawara, Japan

Katsuhiro Tsuneta