Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism – Controlling the head
Reexamination Certificate
2001-01-31
2004-02-17
Sniezek, Andrew L. (Department: 2651)
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Controlling the head
Reexamination Certificate
active
06693764
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to disk drives and more particularly to a technique for improving head position accuracy during track following.
2. Description of the Prior Art
In order to remain competitive, disk drive manufacturers must continually provide increased data storage capacity while rigidly controlling disk drive manufacturing cost. One key to increased storage capacity is increased track density, often expressed as tracks per inch or TPI. Market demand for increased storage capacity has pushed disk drive designers to increase the TPI of disk drives, thereby increasing the likelihood that an external vibration may undesirably force the disk drive's read/write head over an adjacent track during track following.
Accordingly, there exists a need for a method that enables a disk drive to minimize the effect of external vibration on head position accuracy during track following without unnecessarily increasing the disk drive's manufacturing cost.
SUMMARY OF THE INVENTION
The present invention may be embodied in a method and a disk drive for improving head position accuracy during track following through real-time identification of external vibration. The method includes providing a plurality of concentric data tracks having data sectors and embedded servo sectors on a storage surface of a rotating disk, positioning the head over a selected track of the plurality of concentric data tracks, and generating head position signal samples based on the position of the head with respect to the track's servo sectors. Position error signal samples are generated based on a difference between the head position signal samples and a reference head position value. The selected track is followed using a servo control loop having a nominal gain and being responsive to the position error signal samples. A spectral power value within a predetermined frequency band is determined from a sequence of the position error signal samples. If a property of the spectral power value exceeds a threshold, the gain of the servo control loop is increased within the predetermined frequency band to attenuate the effect of external vibration on the position of the head over the selected track during track following.
In another embodiment of the invention, spectral power values may be determined for a plurality of frequency bands and the gain may be increased within at least one of the frequency bands if a property of the respective spectral power value exceeds a threshold. Further, the plurality of frequency bands may comprise a first frequency band having a frequency range between about 100 and 300 Hz and a second frequency band having a frequency range between about 300 and 500 Hz. Also, the property of the spectral power value may be based on a variance of the spectral power value.
REFERENCES:
patent: 5550685 (1996-08-01), Drouin
patent: 5608586 (1997-03-01), Sri-Jayantha et al.
patent: 5654840 (1997-08-01), Patton et al.
patent: 5663847 (1997-09-01), Abramovitch
patent: 5774299 (1998-06-01), Baum et al.
patent: 6049441 (2000-04-01), Ottesen
patent: 6493172 (2002-12-01), Morris et al.
patent: 6496320 (2002-12-01), Liu
patent: 2002/0034036 (2002-03-01), Sri-Jayantha et al.
Agarwal Vinay K.
Melkote Hemant
Sheh Edgar D.
Fawcett, Esq. Robroy R.
Shara, Esq. Milad G.
Sniezek Andrew L.
Western Digital Technologies Inc.
LandOfFree
Method and disk drive for improving head position accuracy... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and disk drive for improving head position accuracy..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and disk drive for improving head position accuracy... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3277838