Fujitsu Corporation

Hiroshi Ashikaga

Nobuyuki Suzuki

Shin Tomimoto

The storage deviceprovides a signal detection method for preventing the degradation of an error rate at the time of information reading, caused by the change of a magnetic characteristic due to a non-uniform magnetic storage medium. The storage devicecomprises a storage mediumfor storing information, a reproduction signal generation unit for generating a reproduction signal, a synch mark pattern detection unitfor detecting a synch mark pattern from the reproduction signal, a filter setting unit for setting filters and filtersfor demodulating the reproduction signal and a data detection unitfor detecting data from the demodulated signal.

Method for detecting signal used when reading information from storage device

In a servo pattern deviation correcting method and disk apparatus of the present invention, a read/write head writes information to a disk and reads information from the disk. Servo pattern blocks are written to respective sectors of the disk along a target track. A deviation of each servo pattern block from a position of the track in a transverse direction is detected. A deviation correction pattern for each servo pattern block is created based on the deviation of the servo pattern block. The deviation correction pattern is written to a predetermined region of the disk between each servo pattern block and a data region along the track. The deviation correction pattern is read from the predetermined region of the disk, so that the read/write head is shifted to a deviation-corrected position on the track based on the servo pattern block and the deviation correction pattern.

Servo pattern deviation correcting method and disk apparatus using the same

A disk device and a disk medium are disclosed in which a plurality of servo cylinders on the surface of at least one disk are divided into several areas, and a different servo signal frequency is set and recorded for each of the areas. The servo cylinders are divided into predetermined areas, and a different servo signal frequency for each of the areas is set so that the recording density of the servo signal recorded in the disk can be set so as to allow the servo signal demodulation characteristic to be included in a relatively superior range. In the disk device, the boundary between the area of a first servo signal frequency and the area of a second servo signal frequency adjoining the first servo signal frequency area is preferably formed with an area in which a servo signal pattern written with the first servo signal frequency and a servo signal pattern written with the second servo signal frequency are arranged on the same servo cylinders.

Disk device and disk medium, in which a plurality of servo cylinders formed concentrically from the inner diametrical portion to the outer diametrical portion of at least one disk are divided into predetermined areas

In a servo information detection method and disk apparatus of the present invention, it is determined whether a pattern of detection bits, detected from a vicinity of a servo sync mark of a disk, matches with a given comparison bit pattern. A pattern of tolerance bits is changed based on a location of the disk where the servo sync mark is detected, so that the matching between the detection bit pattern and the comparison bit pattern is performed based on the changed tolerance bit pattern.

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Kawasaki, Japan

Hiroshi Ashikaga