Disk drive generating fly height measurement from servo burst and adjusting by position error signal
View Patent ↗A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of servo tracks defined by servo sectors, wherein each servo sector comprises a plurality of servo bursts. The servo bursts in a servo sector are read to generate a read signal, and a position error signal (PES) is generated in response to the read signal, wherein the PES represents a position of the head over the disk. A fly height measurement (FHM) is generated in response to the read signal, and the FHM is adjusted based on an adjustment value generated in response to the PES.
1. A disk drive comprising:
a disk comprising a plurality of servo tracks defined by servo sectors, wherein each servo sector comprises a plurality of servo bursts;
a head actuated over the disk; and
control circuitry operable to:
read the servo bursts in a servo sector to generate a read signal;
generate a position error signal (PES) in response to the read signal, wherein the PES represents a position of the head over the disk;
generate a first fly height measurement (FHM) in response to the read signal; and
adjust the first FHM based on an adjustment value generated in response to the PES.
2. The disk drive as recited in claim 1 , wherein the control circuitry is further operable to calibrate the adjustment value by scanning the head over a servo track while generating a FHM for a plurality of different PES values.
3. The disk drive as recited in claim 1 , wherein the control circuitry is further operable to generate the adjustment value as a function of the PES.
4. The disk drive as recited in claim 3 , wherein the adjustment value comprises a scalar computed as a function of the PES.
5. The disk drive as recited in claim 4 , wherein the control circuitry is further operable to multiply the first FHM by the scalar.
6. The disk drive as recited in claim 1 , wherein the control circuitry is further operable to:
measure a first harmonic and a second harmonic of the read signal; and
generate the first FHM based on a ratio of the first and second harmonics.
7. A method of operating a disk drive, the disk drive comprising a head actuated over a disk comprising a plurality of servo tracks defined by servo sectors, wherein each servo sector comprises a plurality of servo bursts, the method comprising:
reading the servo bursts in a servo sector to generate a read signal;
generating a position error signal (PES) in response to the read signal, wherein the PES represents a position of the head over the disk;
generating a first fly height measurement (FHM) in response to the read signal; and
adjusting the first FHM based on an adjustment value generated in response to the PES.
8. The method as recited in claim 7 , further comprising calibrating the adjustment value by scanning the head over a servo track while generating a FHM for a plurality of different PES values.
9. The method as recited in claim 7 , further comprising generating the adjustment value as a function of the PES.
10. The method as recited in claim 9 , wherein the adjustment value comprises a scalar computed as a function of the PES.
11. The method as recited in claim 10 , further comprising multiplying the first FHM by the scalar.
12. The method as recited in claim 7 , further comprising:
measuring a first harmonic and a second harmonic of the read signal; and
generating the first FHM based on a ratio of the first and second harmonics.