US 2006/0066980 A1 · Velocity controlled disk drive head retraction after power loss

Abstract

A control apparatus controls retraction of a device carried on a moveable member actuated by an electric motor after a sudden power loss. The control apparatus includes a measuring circuit for measuring a back electromotive force (back EMF) from the electric motor during a measuring phase. The control apparatus also includes a controller which receives the actual velocity and provides a command signal for controlling a magnitude of the drive current based on a commanded velocity and the actual velocity of the moveable member. The control apparatus further comprises a current control loop for providing a command current signal based on the current provided to the electric motor and the command signal, and for providing the electric motor with the drive current during a driving phase based on the command current signal.

Claims30

Dependent claims

A control apparatus for controlling retraction of a device carried on a moveable member actuated by an electric motor after a sudden power loss, the control apparatus comprising:

a measuring circuit for measuring a back electromotive force (back EMF) from the electric motor during a measuring phase, wherein the back EMF from the electric motor is related to an actual velocity of the moveable member;
a controller which receives the back EMF from the electric motor and provides a control signal for controlling a magnitude of a drive current based on a commanded velocity signal and the back EMF from the electric motor;
and
a current control loop for providing a command current signal based on the control signal and a sensed current through the electric motor, and for providing the electric motor with the drive current during a driving phase based on the command current signal.

1 more element

A control apparatus for controlling movement of a device during both a normal operating condition and a power loss operating condition, the device carried on a moveable member actuated by a motor, the control apparatus comprising:

a multiplexer including a normal operation input, a retraction control input, a final drive input, and a multiplexer output, wherein a normal operation signal on the normal operation input is provided at the multiplexer output during the normal operating condition, and wherein a signal selected from the group consisting of a retraction control signal on the retraction control input and a final drive signal on the final drive input is provided at the multiplexer output during the power loss operating condition;
and
a current control loop having an input connected to the multiplexer output for providing the motor with a drive current based on a signal provided on the multiplexer output.

Dependencies are inferred from the claim text.

Velocity controlled disk drive head retraction after power loss

Life of this patent

Velocity controlled disk drive head retraction after power loss

Life of this patent

Abstract

Claims30