Fujitsu Corporation

Takehiko Tsuboi

Yukio Abe

Toshihiko Matsuda

Koji Ikenoya

Hiroyuki Kobayashi

Koji Ishii

Tomoo Furukawa

Tsuyoshi Takahashi

Hiroyuki Mase

Shoichi Shimizu

Masako Kaizumi

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

A magnetic disc apparatus using an electric filter for waveform equalization of a read signal is provided. The optimum parameters are set for every head and the writing and reading operations are executed on the basis of the optimum characteristics. At the start of the use of the apparatus, the control information of the circuit parameters previously recorded on a magnetic recording medium is read out, thereby forming a set value table in which the optimum values of the circuit parameters including at least the electric filter have been stored every magnetic head. After the table was formed, prior to the writing or reading operation, the contents of the set value table corresponding to the designated magnetic head are read out and the circuit parameters of the circuit section including the electric filter are controlled and optimized on the basis of the contents read out.

Magnetic disc apparatus

Growing community of inventors

Kawasaki, Japan

Takehiko Tsuboi