Abstract: A controller for a magnetic disk device acquires a reproduction signal of servo burst data while moving a magnetic head along data tracks that intersect servo tracks at a plurality of points. The controller acquires correction values for correcting repeatable runout on a per servo sector basis based on the reproduction signal. The correction values include a first correction value, which is a correction value for a servo sector at a position where the data track and the servo track are substantially parallel to each other and a second correction value, which is a correction value fora servo sector at a position where the data track and the servo track are not substantially parallel to each other. The controller adjusts the first correction value based on the second correction value, and writes the correction values including the adjusted first correction value onto a magnetic disk.

Abstract: A controller for a magnetic disk device acquires a reproduction signal of servo burst data while moving a magnetic head along data tracks that intersect servo tracks at a plurality of points. The controller acquires correction values for correcting repeatable runout on a per servo sector basis based on the reproduction signal. The correction values include a first correction value, which is a correction value for a servo sector at a position where the data track and the servo track are substantially parallel to each other and a second correction value, which is a correction value fora servo sector at a position where the data track and the servo track are not substantially parallel to each other. The controller adjusts the first correction value based on the second correction value, and writes the correction values including the adjusted first correction value onto a magnetic disk.

Abstract: According to one embodiment, a magnetic disk device including a disk, and a controller which calculates a first corrected value based on a first eccentricity of the disk, and writes a first track based on the first corrected value, wherein when the controller interrupts the process for writing the second track so as to overlap the first track at a first position, the controller measures a second eccentricity of the disk, and compares the first eccentricity with the second eccentricity, and when the first eccentricity is different from the second eccentricity, the controller restarts the process for writing the second track from a second position away from the first position in a radial direction.

Abstract: According to one embodiment, a disk drive having a disk, a read head, a servo controller, and a CPU. In the disk, a multi-spiral servo pattern is recorded. The read head reproduces a hexagon-shaped detection signal from the multi-spiral servo pattern. The servo controller generates amplitudes values for respective frames, from the multi-spiral servo pattern. The CPU performs positional-error calculation by using the amplitude values for the frames. Upon detecting a positional change of the head is detected, the CPU performs the positional-error calculation by using the amplitude values generated at the time of replacing the frames with other frames, and corrects the positional error by adding an offset determined from the positional change of the head, to the result of the positional-error calculation.

Abstract: According to one embodiment, there is to provide a disk drive which calculates an error in the position of a head on the basis of concentric servo patterns. The disk drive has a disk medium on which spiral servo patterns are recorded and a read head which reads the spiral servo patterns from the disk medium. A servo controller reproduces a hexagonal burst signal from the spiral servo patterns read by the read head to generate position data associated with servo burst signals. The CPU uses the position data to perform a position error calculation.

Abstract: According to one embodiment, there is to provide a servo write method of writing a multi-spiral servo pattern to a disk medium, the method including a process of writing a spiral index pattern to the disk medium, the spiral index pattern being a spiral pattern including the same region as that of a servo burst signal included in the spiral servo pattern and a region that allows the spiral index pattern to be distinguished from the spiral servo pattern, the spiral index pattern being used as a reference for a write start.

Abstract: According to one embodiment, there is provided a servo write method of writing specified servo patterns to a disk medium on the basis of a spiral servo pattern recorded on the disk medium, wherein when the spiral servo pattern is read using a head, position detecting data used to detect a radial position on the disk medium on the basis of data recorded in a sync mark region.

Abstract: According to one embodiment, a disk drive includes a detection signal producing module configured to produce a detection signal by reading each of the spiral servo patterns, the spiral servo patterns being read by a head while the head scans a circumferential direction region on the disk media. A position error computation module is configured to produce servo burst signals A, B, C, and D using a plurality of frames obtained by dividing the detection signal at even time intervals, at least one burst signal of the servo burst signals being produced using at least two frames in the frames, and to compute a position error of the head based on amplitude values of the produced burst signals.

Abstract: According to one embodiment, a servo writing apparatus that writes a multi-spiral servo pattern to a disk medium is disclosed. The apparatus has a servo controller that generates a servo clock determining a head seek start timing, a servo pattern generator that generates a sector index pulse determining the interval at which a multi-spiral servo pattern is written to the disk medium, a clock phase difference measuring unit that measures a phase difference between the servo clock and the sector index pulse, and a controller that adjusts the measured phase difference.

Abstract: According to one embodiment, a disk drive includes a detection signal producing module configured to produce a detection signal by reading each of the spiral servo patterns, the spiral servo patterns being read by a head while the head scans a circumferential direction region on the disk media. A position error computation module is configured to produce servo burst signals A, B, C, and D using a plurality of frames obtained by dividing the detection signal at even time intervals, at least one burst signal of the servo burst signals being produced using at least two frames in the frames, and to compute a position error of the head based on amplitude values of the produced burst signals.

Abstract: According to one embodiment, a method of writing a target servo pattern constituting concentric servo tracks on a disk medium provided in a disk drive. In the method, a cumulative amplitude value of the waveform of each spiral servo pattern reproduced by the head of the disk drive is calculated, a slope of each spiral servo pattern is calculated from the cumulative amplitude value, and a pitch at which the head should be moved to write the target servo pattern is determined on the basis of the slopes of the spiral servo patterns.

Abstract: According to one embodiment, there is provided a disk drive has a controller that performs positioning control of a head on a data track with a variable track width. The disk drive has a disk in which concentric servo tracks are configured at regular intervals and in which the positions of the individual servo tracks and servo data including position information that enables a position in the range of a servo track width to be detected in units of a specific minimum offset are recorded. The controller performs positioning control of the head on a data track with a variable track width on the basis of the servo track.

Abstract: According to one embodiment, a disk drive having a disk, a read head, a servo controller, and a CPU. In the disk, a multi-spiral servo pattern is recorded. The read head reproduces a hexagon-shaped detection signal from the multi-spiral servo pattern. The servo controller generates amplitudes values for respective frames, from the multi-spiral servo pattern. The CPU performs positional-error calculation by using the amplitude values for the frames. Upon detecting a positional change of the head is detected, the CPU performs the positional-error calculation by using the amplitude values generated at the time of replacing the frames with other frames, and corrects the positional error by adding an offset determined from the positional change of the head, to the result of the positional-error calculation.

Abstract: According to one embodiment, a servo writing apparatus that writes a multi-spiral servo pattern to a disk medium is disclosed. The apparatus has a servo controller that generates a servo clock determining a head seek start timing, a servo pattern generator that generates a sector index pulse determining the interval at which a multi-spiral servo pattern is written to the disk medium, a clock phase difference measuring unit that measures a phase difference between the servo clock and the sector index pulse, and a controller that adjusts the measured phase difference.

Abstract: According to one embodiment, there is to provide a disk drive which calculates an error in the position of a head on the basis of concentric servo patterns. The disk drive has a disk medium on which spiral servo patterns are recorded and a read head which reads the spiral servo patterns from the disk medium. A servo controller reproduces a hexagonal burst signal from the spiral servo patterns read by the read head to generate position data associated with servo burst signals. The CPU uses the position data to perform a position error calculation.

Abstract: According to one embodiment, there is provided a servo write method of writing specified servo patterns to a disk medium on the basis of a spiral servo pattern recorded on the disk medium, wherein when the spiral servo pattern is read using a head, position detecting data used to detect a radial position on the disk medium on the basis of data recorded in a sync mark region.

Abstract: According to one embodiment, there is to provide a servo write method of writing a multi-spiral servo pattern to a disk medium, the method including a process of writing a spiral index pattern to the disk medium, the spiral index pattern being a spiral pattern including the same region as that of a servo burst signal included in the spiral servo pattern and a region that allows the spiral index pattern to be distinguished from the spiral servo pattern, the spiral index pattern being used as a reference for a write start.

Abstract: According to one embodiment, in a disk drive having the function of performing a self-servo writing, the CPU is configured to calculate correction values for only those of servo tracks which have been designated and to store the correction values in servo sectors, when a process of calculating STW-RRO correcting values during a self-run test.

Abstract: According to one embodiment, a method of writing a target servo pattern constituting concentric servo tracks on a disk medium provided in a disk drive. In the method, a cumulative amplitude value of the waveform of each spiral servo pattern reproduced by the head of the disk drive is calculated, a slope of each spiral servo pattern is calculated from the cumulative amplitude value, and a pitch at which the head should be moved to write the target servo pattern is determined on the basis of the slopes of the spiral servo patterns.

Abstract: According to one embodiment, a disk drive having a disk medium on which servo data is recorded, and a control unit that controls the positioning of a head, moving the head to a target position on the disk medium in accordance with the servo data. The servo data contains servo-burst patterns written in units of servo-track pitches. A part of each servo-burs pattern is invalidated (trimmed).