Abstract: A method of writing product servo sectors to a disk of a disk drive is disclosed. The disk comprises a plurality of spiral tracks, wherein each spiral track comprises a high frequency signal interrupted by a sync mark at a sync mark interval. The head internal to the disk drive is used to read the spiral tracks to generate a read signal. The read signal is integrated to generate a ramp signal, wherein a position error signal is generated from the ramp signal. The position error signal is used to maintain the head internal to the disk drive along a servo track while writing product servo sectors along the servo track.

Abstract: A method of writing product servo sectors to a disk of a disk drive is disclosed. The disk comprises a plurality of spiral tracks, wherein each spiral track comprises a high frequency signal interrupted by a sync mark at a sync mark interval. The sync marks in the spiral tracks are detected to synchronize a servo write clock used to open a demodulation window during which the high frequency signal in the spiral tracks is demodulated to generate a position error signal for maintaining the head along a first servo track while writing product servo sectors along the first servo track. The demodulation window is then shifted by an integer number of sync mark intervals to initiate a seek to a second servo track. The head is then used to write product servo sectors along the second servo track.

Abstract: A disk drive is disclosed having a disk comprising a plurality of spiral tracks, a head actuated over the disk, and control circuitry operable to process the spiral tracks in an interleaved manner to write a plurality of product servo sectors to the disk to define a plurality of radially spaced, concentric data tracks.

Abstract: A method and apparatus is disclosed for writing product servo sectors to a disk of a disk drive to define a plurality of data tracks. The disk drive comprises the disk and a head actuated over the disk. The disk comprises a plurality of spiral tracks which are read using the head to synchronize a write clock and to generate a position error signal (PES) according to a PES algorithm used to maintain the head along a first servo track while writing product servo sectors along the first servo track. The PES algorithm is adjusted to seek the head to a second servo track, and the head is used to write product servo sectors along the second servo track.

Abstract: A disk drive is disclosed comprising a disk having a plurality of servo bursts written using perpendicular magnetic recording, wherein each servo burst is written at a servo burst frequency. A fill pattern is written between the servo bursts using perpendicular magnetic recording at a frequency substantially equal to an even harmonic of the servo burst frequency, and a phase shift occurs at the transition between the servo burst and the fill pattern. A head is actuated over the disk, and a sampling device samples a read signal emanating from the head to generate a sequence of read signal sample values. Control circuitry demodulates the servo bursts from the sequence of read signal sample values by computing a single-point Discrete Fourier Transform (DFT) at the servo burst frequency.

Abstract: A method is disclosed for reducing disk expansion effects while writing spiral reference patterns on a disk of a disk drive. The disk drive comprises control circuitry and a head disk assembly (HDA) for positioning a head radially over the disk. In the method, an external spiral servo writer is used to control a radial location of the head for writing a plurality of the spiral reference patterns between inner and outer seed tracks. A head velocity profile is adjusted for writing each spiral reference pattern to account for thermal disk expansion. The head internal to the disk drive is used to read the spiral reference patterns in order to write product servo bursts to the disk that define a plurality of radially-spaced circular data tracks.

Abstract: A method of manufacturing a disk drive by demodulating product servo sectors and spiral tracks written on a disk of the disk drive is disclosed. An external spiral servo writer writes a plurality of spiral tracks that spiral from an outer diameter to an inner diameter of the disk. Each spiral track comprises a high frequency signal interrupted at a predetermined interval by a sync mark. The spiral tracks are used to write product servo sectors to the disk during a fill operation. Common circuitry, such as burst demodulation circuitry, is used to demodulate the high frequency signal in the spiral tracks during the fill operation as well as demodulate the product servo sectors.

Abstract: A method and apparatus is disclosed for adjusting the track density over the disk radius by changing the slope of spiral tracks used to servo write a disk drive. A plurality of spiral tracks are written to the disk wherein each spiral track comprises a high frequency signal interrupted at a predetermined interval by a sync mark. A slope of the spiral tracks over a first radial segment of the disk is substantially steeper than the slope of the spiral tracks over a second radial segment of the disk. The head internal to the disk drive is used to read the spiral tracks in order to write product servo sectors to the disk to define a plurality of data tracks. The steeper slope of the spiral tracks over the first radial segment causes a track density of the data tracks to be lower over the first radial segment compared to the track density of the data tracks over the second radial segment.

Abstract: A method of writing product servo sectors to a disk of a disk drive is disclosed. An external spiral servo writer writes a plurality of reference servo sectors at an outer diameter of the disk and a plurality of spiral tracks that spiral from an outer diameter to an inner diameter of the disk. At the beginning of the product servo writing process, the reference servo sectors are demodulated to initially synchronize a servo write clock. The spiral tracks are then demodulated to maintain synchronization of the servo write clock as well as maintain the head along a target circumferential path while writing product servo sectors to the disk.