Spindle controller with startup correction of disk position

Claim 2

A disk drive, comprising: a spindle motor; a disk mounted on said spindle motor; a sensor coupled to said spindle motor to generate a sensor signal having multiple pulses per revolution of said spindle motor corresponding to equally-separated angular positions thereof; means for controlling the drive current provided to said spindle motor in a manner effective to phase-align an arbitrary pulse of a phase shifted sensor signal with a command reference signal received by said controlling means whose frequency equals the desired rotational frequency of said spindle; means for generating a reference position signal indicating a predetermined angular position of said disk; a timer to measure the phase difference between said command reference signal and said reference position signal; means for determining from the measured phase difference a number of consecutive pulses by which said sensor signal should be phase-shifted to phase-align said command reference signal and said reference position signal; and a phase shifter to phase-shift said sensor signal by the determined number of pulses to produce said phase shifted sensor signal.

Claim 3

A disk drive according to claim 1, wherein said determining means comprises: a memory containing a table of time values and a table of pulse numbers; a processor coupled to said timer and to said memory to compare the measured phase difference to said time values in order to determine a closest time value thereto, and to retrieve a pulse number associated with the closest time value.

Claim 4

A disk drive according to claim 1, wherein said reference position signal generating means comprises: a pattern written at a reference position on a surface of said disk; a read head associated with said disk; and a head position detector coupled to said read head to detect said pattern and to generate said reference position signal in response to the detection thereof.

Claim 5

A disk drive according to claim 1, wherein said sensor comprises multiple Hall effect sensors mounted on said spindle motor.

Claim 6

A disk drive according to claim 1, wherein said sensor comprises means for sensing the back EMF on the windings of said spindle motor.

Claim 7

A disk drive according to claim 1, wherein said controlling means comprises: a phase detector coupled to said phase shifter to generate an error signal proportional to the phase difference between the phase-shifted sensor signal and said command reference signal; a loop filter coupled to said phase detector to generate a filtered control signal in response to said error signal; and power drivers coupled to said loop filter and to said spindle motor to provide current proportional to said filtered control signal to the windings of said spindle motor.

Claim 8

A disk drive, comprising: a spindle motor; a sensor coupled to said spindle motor to generate a sensor signal having multiple pulses per revolution of said spindle motor corresponding to equally-separated angular positions thereof; a disk mounted on said spindle motor having a pattern written at a reference position on a surface thereof; a read head associated with said disk; a head position detector coupled to said read head to detect said pattern and to generate a reference position signal in response to the detection thereof; a trigger pulse modifier coupled to said sensor and said head position detector to generate a trigger signal in response to said sensor signal, said reference position signal, and a command reference signal to be supplied thereto, said trigger pulse modifier having (i) a timer to measure the phase difference between said command reference signal and said reference position signal, (ii) means for determining from the measured phase difference a number of pulses by which said sensor signal should be phase-shifted to phase-align said command reference signal and said reference position signal, and (iii) a phase shifter to produce said trigger signal by phase-shifting said sensor signal by the determined number of pulses; a frequency divider coupled to said trigger pulse modifier to generate a feedback signal by dividing said trigger signal by a number equal to the number of pulses of said sensor signal per revolution of said spindle; a phase detector coupled to said frequency divider to generate an error signal proportional to the phase difference between said feedback signal and said command reference signal; a loop filter coupled to said phase detector to generate a filtered control signal in response to said error signal; and power drivers coupled to said loop filter and to said spindle motor to provide current proportional to said filtered control signal to the windings of said spindle motor.

Claim 9

A disk drive, comprising: a spindle motor; a sensor coupled to said spindle motor to generate a sensor signal having multiple pulses per revolution of said spindle motor corresponding to equally-separated angular positions thereof; a disk mounted on said spindle motor having a pattern written at a reference position on a surface thereof; a read head associated with said disk; a head position detector coupled to said read head to detect said pattern and to generate a reference position signal in response to the detection thereof; a trigger pulse modifier coupled to said sensor and said head position detector to generate a trigger signal in response to said sensor signal, said reference position signal, and a command reference signal to be supplied thereto, said trigger pulse modifier having (i) a timer to measure the phase difference between said command reference signal and said reference position signal, (ii) means for determining from the measured phase difference a number of pulses by which said sensor signal should be phase-shifted to phase-align said command reference signal and said reference position signal, and (iii) a phase shifter to produce said trigger signal by phase-shifting said sensor signal by the determined number of pulses; a frequency divider coupled to said trigger pulse modifier to generate a feedback signal by dividing said trigger signal by a number equal to the number of pulses of said sensor signal per revolution of said spindle; a phase detector coupled to said frequency divider to generate an error signal proportional to the phase difference between said feedback signal and said command reference signal; a loop filter coupled to said phase detector to generate a filtered control signal in response to said error signal; and power drivers coupled to said loop filter and to said spindle motor to provide current proportional to said filtered control signal to the windings of said spindle motor.

Claim 12

A method according to claim 8, wherein said phase-shifting step comprises the step of inserting the determined number of pulses into said sensor signal.

Claim 13

A method according to claim 8, wherein said phase-shifting step comprises the step of inhibiting the determined number of pulses in said sensor signal.