Abstract: A method for writing circular track position information on a magnetic recording disk comprising the steps of (i) rotating the magnetic recording disk, and (ii) aerodynamically floating in a helium atmosphere a magnetic recording head adjacent to the disk and writing with the head circular track position information on the disk.

Abstract: A servo system uses a disk on which two pairs of burst data items A and B and burst data items C and D are prerecorded, and the servo system performs positioning control for positioning a head within a range of a track on a disk. The servo system sets a range of a track to be divided into a first area regarding the track center as a reference position, a second area regarding a boundary position between tracks as a reference position, and a third area regarding a middle position between the reference positions, as a reference position. In the first area, the servo system calculates position information of the head by a first calculation formula using the burst data items A and B. In the second area, the servo system calculates position information of the head by a second calculation formula using the burst data items C and D. Further, in the third area, the servo system calculates an average value of calculation results from the first and second calculation formulas, as position information.

Abstract: A method and apparatus for generating a position error signal (PES) voltage v. track distance curve for the head of a hard disk drive. The disk has a dedicated track which contains a plurality of servo bits that allow the head to be centered with the centerline of the track. The dedicated track also has a number of calibration bits each embedded at a known location off-set from the track centerline. The PES voltage v. track distance curve is generated by reading each calibration bit and storing the corresponding amplitude of the position error signal in a memory device of the disk drive. Each calibration bit is located from the track centerline a distance that is different from the other calibration bits so that there are provided multiple points on the track curve.

Abstract: A disk drive processing system controls a Servo Timing Mark (STM) detection window in disk drive during a head switch operation. In response to the head switch operation, the system disables a timer that closes the STM detection window during normal operation, and the system tracks the elapsed time from a time point. The system compares the elapsed time to a programmable limit value. The system resumes normal operation if an STM is detected before the elapsed time reaches the programmable limit value and initiates a recovery procedure if the elapsed time reaches the programmable limit value. Advantageously, the programmable limit value can be easily re-programmed if a larger STM detection window is required due to severe STM or head mis-alignment.

Abstract: A signal processing device having a feature of analog-to-digital converting a burst signal has a feature of selecting a data bus to notify a disk control device of a conversion result via an NRZ data bus. The disk control device stores the result of the analog-to-digital conversion of the servo positional signal. The positional signal of a head of the disk device is digitalizes in a R/W channel. Sampling for digital conversion is performed in only a window which is defined only in the vicinity of peaks of the positional signal. The values of peaks which are obtained by sampling are averaged by an averaging circuit. This enables the influence of noise occurred outside of the window to be eliminated. Although the noise in the window is sampled, its adverse influence is suppressed by the averaging processing.

Abstract: A technique for measuring a position error signal of a disk drive, includes measuring the width of a track by sequentially following two adjacent tracks upon turning on power, and updating a percentage of the position error signal according to the measurement of the track width.

Abstract: A method of providing the servo pattern for detecting fine defects in the servo burst signals of a hard disk drive (HDD) comprises the steps of writing a preamble portion for providing a servo sync signal in reading servo data together with a gap to inform of a servo sector, writing a servo address mark (SAM) for notifying the start of the servo to provide a sync signal to read the following gray code, writing the gray code for providing the identification data ID of a track, and writing a burst signal portion consisting of multiple repetition of the position error signal required for even or odd numbered track data and track following.