Fujitsu Corporation

Koji Ikenoya

Yukio Abe

Takehiko Tsuboi

Hiroyuki Kobayashi

Koji Ishii

Toshihiko Matsuda

Tomoo Furukawa

Tsuyoshi Takahashi

When a combination head is on-tracked to an arbitrary cylinder position, a head position controller corrects a head position so as to eliminate an offset amount derived from an offset table. A bias current setting circuit obtains a current set value corresponding to an offset correction amount from a bias current table and supplies the bias current according to the current set value to an MR head. As kinds of offsets, there are a yaw angle offset, a thermal offset, and a core deviation offset.

Head assembly having a table for storing a head offset and bias current

A device for recording and reproducing data on a recording media includes an error detecting unit for detecting a defective sector by reading the data from the media, a data copying unit for copying the data of the defective sector to at least one temporary replacing sector, a test unit for testing whether the defective sector has a media defect, and a replacement unit for replacing the defective sector with a spare sector by copying the data of the at least one temporary replacing sector to the spare sector when the defective sector has the media defect.

Recording/reproducing device and method of replacing defective sector on

Servo information is written on a magnetic disk at intervals equivalent to 1/N of where the period at the position of a head is controlled. When the frequency characteristic of a servo loop is measured, a servo controller generates a position signal, which indicates deviation of the head from a reference position, using servo information at a first sampling point, calculates an actuator drive current command value, which drives an actuator, on the basis of the position signal, and controls the actuator based upon the current command value. Further, the servo controller executes processing for generating the position signal, but does not calculate the actuator drive current command value, on the basis of servo information at second through Nth sampling points. A frequency characteristic analyzer inserts a disturbance signal having a predetermined frequency into the servo loop, accepts, at double the sampling frequency, the position signal and the actuator drive current generated based upon each item of servo information, obtains the frequency characteristic of the servo loop and outputs the frequency characteristic.

Disk apparatus and method of measuring frequency characteristic thereof

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Kawasaki, Japan

Koji Ikenoya