Fujitsu Corporation

Toshiki Kimura

Tsuyoshi Takahashi

Isamu Tomita

Kiichiro Kasai

Kenji Itou

Masayoshi Ishii

An automatic calibration method for a read system in which data read by a head from a recording medium is demodulated using a partial response method which includes the steps of: storing at least one of a parameter relating to a bias current fed to the head and parameters necessary for data demodulation in the read system, for a plurality of operating conditions; and automatically calibrating the at least one parameter to a preset value suitable for an operating condition.

Automatic calibration method, read apparatus and storage apparatus

A magnetic disk reproducing apparatus for reproducing data recorded at an arbitrary position on a rotating disk by a head includes a level detecting unit for detecting a level of a DC component of a reproduced signal outputted from the head; a delaying unit for delaying the reproduced signal by a predetermined value; and a correcting unit for correcting the level of the DC component of the reproduced signal outputted from the delaying unit when the level of the DC component detected by the level detecting unit becomes larger than a predetermined threshold level. Preferably, a control method of a magnetic disk reproducing apparatus having such a construction includes the steps of detecting a level of a DC component of a reproduced signal outputted from the head; delaying the reproduced signal by a predetermined value; and correcting the level of the DC component of the delayed reproduced signal when the level of the DC component so detected becomes larger than a predetermined threshold level.

Magnetic disk reproduction with offset compensation for thermal asperity

Disclosed is an off-track correcting method for a disk apparatus for measuring an off-track correction value by use of servo data on a data surface. The data surface on a disk medium is recorded with servo data for an off-track measurement. The data head seals a cylinder position recorded with the off-track measurement servo data. It is determined whether or not this cylinder position is a sensitivity abnormal position of the cylinder. The data head reads a first item of servo data after offset-moving the data head by a predetermined quantity on inner and outer sides of the disk medium, corresponding to detecting that the data head is located in the sensitivity abnormal position. An off-track correction value in the cylinder position is calculated from the plural pieces of first servo data read finally in a plurality of reading positions. This, even when enhancing a track density, the precise off-track correction value can be thereby measured.

Off-track correcting method of disk apparatus and a disk apparatus using

A method for optimizing a write offset margin includes the steps of writing test data on a recording medium along a track defined thereon by a head, reading the test data from the recording medium by the head while changing an offset of the head with respect to the track, determining a maximum offset that provides agreement between the test data written into the recording medium along the track by the head and the test data read out from the recording medium by the head along the track, and setting a write offset margin for the magnetic disk based upon the maximum offset.

Disk drive having optimized off-track compensation

A disc-drive apparatus includes a writing unit responsive to a head select signal fed from a host controller, for selecting one of a plurality of heads to write write data into a medium, a power supply voltage generating unit for generating at least one power supply voltage, a unit for monitoring the power supply voltage fed to the writing unit and, upon detecting an abnormality of the monitored power supply voltage, outputting a reset signal, and a latching unit for retaining the head select signal to be fed to the writing unit. Upon receipt of the reset signal, the latching unit prohibits a latching and switching operation to be carried out by a subsequent head select signal fed from the host controller and maintains an output state of the retained head select signal, while the power supply voltage generating unit stops a supply of the power supply voltage to the writing unit. As a result, it is possible to prevent data in the medium from being destroyed due to a change or re-writing thereof by a malfunction of head selection operation occurring during a transient state of a lowering of the power supply voltage, or the like.

Disc-drive apparatus having function of preventing destruction of data

A data reproducing circuit, and more particularly, a data reproducing circuit which records magnetization reversal patterns corresponding to a written digital signal onto a magnetic recording medium, and converts a received analog signal from the magnetic recording medium into a digital signal. The present invention has a pre-shift circuit to perform peak shift compensation in the recording process, an equalizer to perform peak shift compensation in the reproducing process, and a digital data reproducing circuit to reproduce data by differentiating the equalized signal received from the equalizer and generating a window signal. The equalizer means contains the first equalizer which compensates the peak position shifting in the received analog signal from the magnetic head and outputs the equalized signal used for differentiation, and the second equalizer which corrects the peak level variation of the analog signal and outputs the equalized signal used for window signal generation. Use of these equalizers with the pre-shift circuit assures margins for noises in the reproducing process along with a sufficient peak shift compensation.

Apparatus and method for reading from and writing to a magnetic

A data reproducing circuit for a memory system having a data sensing head includes a first equalizing circuit for correcting a shift of a position of a peak of a reproduction signal supplied from the data sensing head and for generating a first signal in which the shift of the position of the peak has been corrected, and a second equalizing circuit for correcting a variation in an amplitude of the reproduction signal supplied from the data sensing head and for generating a second signal in which the variation of the amplitude of the reproduction signal has been corrected. A peak position detecting circuit detects the position of the peak of the reproduction signal from the first signal supplied from the first equalizing circuit. An amplitude detecting circuit detects the amplitude of the reproduction signal from the second signal supplied from the second equalizing circuit. A gate circuit generates a pulsed reproduction signal from the peak position detected by the peak position detecting circuit and the amplitude detected by the amplitude detecting circuit.

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Kawasaki, Japan

Toshiki Kimura