Fujitsu Corporation

Toshiba Storage Device Corporation

Kazuhide Ohba

Eisaku Takahashi

Eiji Okamura

Atsushi Satoh

Yoshimichi Sakai

Isao Suda

Tatsuya Gofuku

Chihiro Ono

Takao Furuhashi

Takashi Tokairin

Tsutomu Sasaki

Hideki Ohmori

Hirofumi Suzuki

Norihiko Suzuki

Takahiro Ono

Hajime Miura

Koichi Tohkairin

Kenji Endo

Kensuke Miyagawa

Hirokazu Ishizaki

Masaru Saiki

The present invention relates to a magnetic disk device and provides a magnetic disk device in which data recording areas are separately set based on the inner recording boundary or outer recording boundary of the head measured for each magnetic disk device. When the recording linear (angular) density that has to be attained to ensure a prescribed capacity cannot be attained by the head, the recording linear (angular) density that has to be attained by the head is reduced and the prescribed capacity is realized by expanding the data recording area. A method using a counter-electromotive force generated when the head is moved toward a stopper or ramp load or a method by which the measurements are conducted based on the head position information from the servo signal can be used for measuring the positions of the inner recording boundary and outer recording boundary of the head.

Magnetic disk devices with data recording areas set separately for each device

Disk unit creating a position sensitivity correction value using positive and negative cross points values of two-phase servo signals

A disk apparatus has a disk medium with sector areas that have a servo area and a data area along the same cylinder. The servo areas also have a sector mark indicative of the servo area, a code indicative of a cylinder address, and a predetermined servo pattern to detect a head position, all magnetically recorded in the servo area. A disk control section uses a head portion to detect the head position on the basis of a read signal of the servo pattern and positions the head portion at an arbitrary cylinder to perform reading and writing operations. The disk apparatus also has a time measuring counter for starting to measure an elapsed time each time a predetermined position in the servo area is detected, and a time setting register for storing a time from a detection time point of the predetermined position in the servo area to the generation of the sector pulse. A coincidence detecting section is provided to detect that the elapsed time measured by the time measuring counter coincides with the set time of the register, while a pulse generating section is provided for generating the sector pulse when the coincidence is detected by the coincidence detecting section.

Disk apparatus using coincidence detection to generate variable sector

A method is provided to adjust a bias current flowing through a magneto-resistive effect type magnetic head. An examining current is supplied to the magneto-resistive effect type magnetic head, and a voltage applied to a pair of terminals of the magneto-resistive effect type magnetic head is measured. In addition, a resistance of the magneto-resistive effect type magnetic head is calculated according to the examining current and the voltage, and an allowable range of the bias current flowing through the magneto-resistive effect type magnetic head is determined according to a relationship between a life time of the magneto-resistive effect type magnetic head examined in advance and the resistance of the magneto-resistive effect type magnetic head. An optimum bias current is determined within the allowable range in condition that a slice level margin is maximized.

Method and apparatus for adjusting a bias current of a magneto-resistive

For a balance adjustment due to a reduction in size and weight of an actuator, an arm portion, an axis attaching portion, and a coil supporting portion are arranged so that the centers of gravity on the coil side are located on a straight line connecting a rotational center and the center of gravity on the head side. Further, the improvement of an assembling efficiency of a VCM, an increase in torque, a one-touch fixing of an FPC connecting band, a noise prevention of a read pattern, and an insulation between the base and cover due to a bias of an MR read head are accomplished. A sector mark is detected by comparing a peak detection pulse and its reference polarity signal. A redundancy is provided to a reference detection polarity signal so that a read signal can be detected even if any one of the read signals of the sector marks is dropped out. A gray code detecting section for recognizing a cylinder address also detects on the basis of a peak detection pulse and a polarity signal due to the reading of a gray code. A memory space to store a program is divided into an ROM space of a small electric power consumption and an RAM space of a large electric power consumption and stores each peculiar program.

Head positioning control for disk apparatus using peak detection,

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Kawasaki, Japan

Kazuhide Ohba