Hitachi, Ltd.

Hitachi Global Storage Technologies Japan, Ltd.

Futoshi Tomiyama

Takehiko Hamaguchi

Hisashi Takano

Hideki Zaitsu

Yasutaka Nishida

Hideki Sawaguchi

Hiroshi Ide

Toru Matsushita

Atsushi Nakamura

Yohji Maruyama

Fumiko Akagi

Reijiro Tsuchiya

Miki Hara

Yuzuru Hosoe

Yoshihiro Shiroishi

Kiwamu Tanahashi

Masukazu Igarashi

Kazuetsu Yoshida

Yotsuo Yahisa

Tomoo Yamamoto

Toshiaki Tsuyoshi

Shinji Narishige

Akira Ishikawa

Naoki Kodama

Takayuki Ichihara

Katsuo Abe

Akira Osaki

Emi Mangyo

In the present invention, by making the width of the write element larger than the track pitch and securing a write magnetic field strong enough to reverse the magnetization of the magnetic layer, and further by writing while shifting a write head comprising the write element, a magnetic disk drive, of which the track width is narrower than the write element width, and the storage capacity is large, is realized.

Magnetic disk drive

There are provided a magnetic head and a magnetic disk apparatus wherein an upper magnetic pole is so shaped that, at a position where skew angle is maximum, the maximum of its projected length in the radial direction of a magnetic disk is not more than the track pitch of the magnetic disk, whereby acceleration of thermal relaxation of information recorded on adjacent tracks is obviated even in an area where the skew angle is large.

Magnetic head with high reliability of the data protection, magnetic disk apparatus including the magnetic head and the method of recording information on the magnetic disk apparatus without miserasing the previously recorded data

Magnetic disk device having a write head to write by shifting in a radial direction

Deterioration in recording performance immediately after the start of recording in a magnetic recording apparatus due to the contraction of the magnetic head element in low atmospheric temperatures is prevented, thus ensuring a stable recording performance irrespective of the ambient temperature. Upon reception of a recording command for first data from a host device, second data already recorded in the same track as that of a data area where information is to be recorded is read and then stored in a memory. Dummy data is then recorded in the data area on the track, and then the first and second data stored in the memory is recorded. Magnetic disc apparatuses for car navigation systems, where stable operation under low temperatures is required, can be provided at low cost.

Magnetic recording apparatus and method of writing data at low temperature

MAGNETIC HEAD WITH HIGH RELIABILITY OF THE DATA PROTECTION, MAGNETIC DISK APPARATUS INCLUDING THE MAGNETIC HEAD AND THE METHOD OF RECORDING INFORMATION ON THE MAGNETIC DISK APPARATUS WITHOUT MISERASING THE PREVIOUSLY RECORDED DATA

The invention relates to a magnetic recording/reproducing device in which a reproduce head is positioned where the crosstalk between adjacent tracks in a magnetic disk is minimized to maintain an adequate transfer rate in a system involving great crosstalk. The removal of crosstalk ensures the reproduction of the recorded data and thus increases the reliability of the magnetic recording/reproducing device. The magnetic recording/reproducing device according to this invention includes a magnetic disk on which a plurality of tracks are concentrically formed, and data are recorded at different frequencies on adjacent tracks.

Magnetic recording/reproducing device

A magnetic disk drive has a low power consumption state in which the spindle motor is stopped for reducing the average power consumption when no read or write commands have been received. When a read or write command is received, the spindle motor is started. The time it takes to complete a read command is shorter than that for a write command as measured from the receipt of the read command or write command with the spindle motor stopped in the low power consumption state.

A magnetic recording disk drive can prevent the deterioration of the head off-track characteristics and the reduction of the drive performance even when an erase band asymmetry resulting from a skew angle exists. A write inhibit slice value for an inner peripheral side offset is made smaller than a write inhibit slice value for an outer peripheral side offset at a position where an erase band on the inner peripheral side is greater than an erase band on the outer peripheral side, so that the adjacent track on the outer peripheral side cannot easily erase a data track. On the contrary, the inner periphery and the outer periphery are paraphrased at a position where the erase band on the outer peripheral side is greater than the erase band on the inner peripheral side.

Magnetic recording disk drive

To improve the track density by reducing the discontinuity of servo patterns to be generated by a servo track writer, some servo areas existing in one circuit of a magnetic disk are formed at the consecutive first and second circuits of a servo track writer by averaging a plurality of position signals detected from servo patterns at the first and second circuits of the magnetic disk.

When the amount of position error PE of a magnetic head meets the condition of Ewf>PE>&equals;Eww for two threshold values Ewf and Eww meeting Ewf>Eww, the track is registered in the track information table as a track requiring rewrite and the tracks on both sides neighboring to the track are temporarily write-inhibited. The data of the track is rewritten on another track later so as to maintain the data. By doing this, the offtrack of the recording track can be made smaller without sacrifice of the access speed and the occurrence probability of write fault can be reduced. Furthermore, the reliability of a magnetic disk apparatus can be improved.

Method of controlling read write operation of a magnetic disk apparatus

An object is to provide a magnetic recording medium giving high resolution, low noise and little thermal fluctuation and thus suitable for high density magnetic recording, and a high-capacity magnetic recording device realized by using this medium. A thin film type magnetic recording medium is used, having at least 2 magnetic layers formed on a non-magnetic substrate and a non-magnetic intermediate layer that is interposed between the magnetic layers and causes the magnetizations of the magnetic layers to be anti-parallel to one another, and wherein the ratio HkB/HkA of the anisotropic magnetic field strength HkB of the magnetic layer on the side near to the substrate to the anisotropic magnetic field strength HkA of the magnetic layer on the side far from the substrate is 0.7 or less, more preferably at least 0.4 and not more than 0.65.

Magnetic recording medium

A plurality of patterns are formed so that each is deviated slightly from another in each sector in the track width direction. Then, the pattern is followed up, thereby obtaining both a full-track profile and a micro-track profile. A variation of a position signal is detected from this profile, thereby creating a table for correcting the non-linearity error of the position signal. Consequently, the distribution of the write/read-back property is measured, thereby enabling the track density to be improved. Furthermore, a variation of the position signal caused by a property variation of the head read-back element is detected and corrected, thereby enabling a high reliability and a high track density to be realized for the object magnetic recording disk apparatus.

Method and system for compensation of nonlinearity or fluctuation of head-position signal

Growing community of inventors

Hachioji, Japan

Futoshi Tomiyama