US 5,329,409 A · Correction of current feedback offset for disc drive servo systems

Abstract

A process is provided for compensating for offset in the actuator current of the servo system of a disc drive. A typical disc drive includes a power amplifier providing actuator current to the actuator coil of the drive. A sensing resistor is responsive to the actuator current to provide a feedback signal representative of the magnitude of the actuator current, the feedback signal being provided to the power mechanism to derive the actual actuator current. By the present technique, offset in the actuator current is compensated by operating the transducer to move at predetermined constant velocities (for example, the maximum velocities) in first and second opposite directions across the surface of the disc and by measuring the resulting actual velocities. The feedback signal is adjusted based upon any difference between the actual velocities measured in the first and second directions.

Claims23

Dependent claims

In a disc drive having power means responsive to a feedback signal for providing actuator current to an actuator, the actuator being operable in response to the actuator current to accelerate and decelerate a transducer, and a sensor responsive to the actuator current for deriving the feedback signal representative of the magnitude of the actuator current, the method of compensating for offset comprising:

operating the actuator in a manner designed to move the transducer at a predetermined constant speed in a first direction;
operating the actuator in a manner designed to move the transducer at the same constant speed in a second direction opposite the first direction;
determining first and second actual speeds at which the transducer moves in the respective first and second directions;
and
altering said signal feedback if the first and second actual speeds differ by more than a predetermined difference.

2 more elements

In a disc drive having an actuator operable in response to a signal to accelerate and decelerate a transducer, the method of compensating said signal for offset comprising:

operating said actuator in a manner designed to move said transducer at a predetermined constant speed in a first direction for a predetermined distance;
operating said actuator in a manner designed to move said transducer at the same constant speed in a second direction opposite the first direction for the same distance;
determining first and second time intervals during which said transducer moves in said respective first and second directions;
and
altering said signal if said first and second time intervals differ by more than a predetermined difference.

2 more elements

Dependencies are inferred from the claim text.

Correction of current feedback offset for disc drive servo systems

Life of this patent

Correction of current feedback offset for disc drive servo systems

Life of this patent

Abstract

Claims23