Disk drive employing pulse width modulation of head control signal
View Patent ↗A disk drive is disclosed comprising a plurality of disk surfaces, and a plurality of heads actuated over the respective disk surfaces. In one embodiment, control circuitry generates a pulse duty cycle signal for one of the heads. In another embodiment, the control circuitry generates a first pulse width modulated signal for a first head, and a second pulse width modulated signal for a second head, wherein the second pulse width modulated signal comprises a phase offset from the first pulse width modulated signal.
1. A disk drive comprising:
a plurality of disk surfaces;
a plurality of heads actuated over the respective disk surfaces; and
control circuitry operable to generate a first pulse duty cycle signal for a first head and generate a second pulse duty cycle signal for a second head simultaneous with generating the first pulse duty cycle signal for the first head, wherein:
the first pulse duty cycle signal comprises a pulse width modulated signal comprising an on-time that is pulsed; and
the second pulse duty cycle signal is generated with a phase offset from the first pulse duty cycle signal.
2. The disk drive as recited in claim 1 , wherein the first pulse duty cycle signal controls a fly height of the first head.
3. The disk drive as recited in claim 1 , wherein the phase offset is selected so that only one of the first and second pulse duty cycle signals dissipates power at a time.
4. A disk drive comprising:
a plurality of disk surfaces;
a plurality of heads actuated over the respective disk surfaces; and
control circuitry operable to:
generate a first pulse width modulated signal for a first head; and
generate a second pulse width modulated signal for a second head, wherein the second pulse width modulated signal comprises a phase offset from the first pulse width modulated signal.
5. The disk drive as recited in claim 4 , wherein the first pulse width modulated signal controls a fly height of the first head.
6. The disk drive as recited in claim 4 , wherein:
the first pulse width modulated signal comprises a first duty cycle adjusted in a first direction; and
the second pulse width modulated signal comprises a second duty cycle adjusted in a second direction opposite the first direction.
7. The disk drive as recited in claim 4 , wherein:
the first pulse width modulated signal comprises a first pulse duty cycle signal; and
the second pulse width modulated signal comprises a second pulse duty cycle signal.
8. The disk drive as recited in claim 4 , wherein the phase offset is selected so that only one of the first and second pulse width modulated signals dissipates power at a time.
9. A method of operating a disk drive, the disk drive comprising a plurality of disk surfaces, and a plurality of heads actuated over the respective disk surfaces, the method comprising generating a first pulse duty cycle signal for a first head and generating a second pulse duty cycle signal for a second head simultaneous with generating the first pulse duty cycle signal for the first head, wherein the first pulse duty cycle signal comprises a pulse width modulated signal comprising an on-time that is pulsed and the second pulse duty cycle signal is generated with a phase offset from the first pulse duty cycle signal.
10. The method as recited in claim 9 , wherein the first pulse duty cycle signal controls a fly height of the first head.
11. The method as recited in claim 9 , wherein the phase offset is selected so that only one of the first and second pulse duty cycle signals dissipates power at a time.
12. A method of operating a disk drive, the disk drive comprising a plurality of disk surfaces, and a plurality of heads actuated over the respective disk surfaces, the method comprising:
generating a first pulse width modulated signal for a first head; and
generating a second pulse width modulated signal for a second head, wherein the second pulse width modulated signal comprises a phase offset from the first pulse width modulated signal.
13. The method as recited in claim 12 , wherein the first pulse width modulated signal controls a fly height of the first head.
14. The method as recited in claim 12 , wherein:
the first pulse width modulated signal comprises a first duty cycle adjusted in a first direction; and
the second pulse width modulated signal comprises a second duty cycle adjusted in a second direction opposite the first direction.
15. The method as recited in claim 12 , wherein:
the first pulse width modulated signal comprises a first pulse duty cycle signal; and
the second pulse width modulated signal comprises a second pulse duty cycle signal.
16. The method as recited in claim 12 , wherein the phase offset is selected so that only one of the first and second pulse width modulated signals dissipates power at a time.