Abstract: According to one embodiment, a magnetic disk device includes a magnetic disk, a magnetic head, a position error signal output module, a vibration pattern detector, an adder, and a head positioning controller. The magnetic head moves over the magnetic disk. The position error signal output module outputs a position error signal based on a difference between a head position of the magnetic head over the magnetic disk and a target position on the magnetic disk. The vibration pattern detector detects a vibration pattern of the magnetic head caused by vibration. The adder adds the position error signal to an offset signal indicating amplitude of the vibration pattern. The head positioning controller moves the head position to the target position based on a result of addition by the adder.

Abstract: According to one embodiment, a magnetic recording apparatus includes a magnetic recording medium for perpendicular magnetic recording system, a magnetic head including a read head to read data from the magnetic recording medium, and an actuator to actuate the magnetic head on the magnetic recording medium. The magnetic recording medium includes a first magnetic pattern recorded in a servo area by applying a magnetic field horizontally to a disk surface, and the first magnetic pattern corresponding to positioning data used for positioning the magnetic head. The magnetic recording medium further includes a second magnetic pattern recorded in the servo area by applying a magnetic field perpendicularly to the disk surface, and the second magnetic pattern corresponding to position correction data used for correcting the positioning data. The position correction data is derived from modulated original position correction data. The original position correction data is created for correcting the positioning data.

Abstract: According to one embodiment, a magnetic recording apparatus includes a magnetic recording medium for perpendicular magnetic recording system, a magnetic head including a read head to read data from the magnetic recording medium, and an actuator to actuate the magnetic head on the magnetic recording medium. The magnetic recording medium includes a first magnetic pattern recorded in a servo area by applying a magnetic field horizontally to a disk surface, and the first magnetic pattern corresponding to positioning data used for positioning the magnetic head. The magnetic recording medium further includes a second magnetic pattern recorded in the servo area by applying a magnetic field perpendicularly to the disk surface, and the second magnetic pattern corresponding to position correction data used for correcting the positioning data. The position correction data is derived from modulated original position correction data. The original position correction data is created for correcting the positioning data.

Abstract: According to one embodiment, a magnetic disk device includes a magnetic disk, a magnetic head, a position error signal output module, a vibration pattern detector, an adder, and a head positioning controller. The magnetic head moves over the magnetic disk. The position error signal output module outputs a position error signal based on a difference between a head position of the magnetic head over the magnetic disk and a target position on the magnetic disk. The vibration pattern detector detects a vibration pattern of the magnetic head caused by vibration. The adder adds the position error signal to an offset signal indicating amplitude of the vibration pattern. The head positioning controller moves the head position to the target position based on a result of addition by the adder.

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 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, in a disk drive having a disk medium on which servo data is recorded, servo-write management information is recorded on the disk medium, in the form of binary data based on the 0 or 180 degrees out of phase pattern composed of the servo burst signals included in the servo data and being out of phase. The disk drive includes a servo-data reproducing unit that reproduces the servo-data and the servo-write management information.

Abstract: According to one embodiment, a disk drive is provided which corrects already existing offset information according to a variation of a disk runout amount caused by an occurrence of a disk shift. The disk drive effects a head position adjustment at a head positioning control time with the use of offset information stored in a memory. A CPU measures a variation in the disk runout amount and phase caused by an occurrence of a disk shift resulting from an external shock involved and updates the existing offset information with a correction offset information based on a result of measurement.

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, 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 information writing method for use in a disk drive, for recording the servo information, forming a continuous servo track such as a spiral track. In this servo information writing method, the head is stopped when a write error is detected while the servo information is being written, and the head is then moved again at a constant speed and starts writing the servo information again, at the position where the write error has occurred.

Abstract: According to one embodiment, in a disk drive using a disk medium storing spiral servo information, a CPU generates virtual servo information having assumed virtual track centers corresponding to centers of concentric data tracks. The CPU performs control to position a head to the center of the concentric data track by using the virtual servo information.

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 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 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.