Decreasing spin up time in a disk drive by adjusting a duty cycle of a spindle motor PWM signal to maintain constant average input current
AssigneeWestern Digital Technologies, Inc.
InventorsGeorge J. Bennett, Robert P. Ryan
Life of this patent
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Abstract
A disk drive is disclosed comprising a spindle motor for rotating a disk, wherein the current applied to the spindle motor is controlled by adjusting a duty cycle of a pulse width modulated (PWM) signal. A current sensor generates a current sense signal representing a current flowing from a supply voltage. The current sense signal is integrated to generate an integration signal. The integration signal is compared to a threshold, and the result of the comparison is used to adjust the duty cycle of the PWM signal. In this manner the disk drive draws essentially constant average input current from the supply voltage which decreases the spin up time of the disk.
Claims18
A disk drive connectable to a host computer, the disk drive comprising:
- (a) a disk;
- (b) a head;
- (c) a voice coil motor (VCM) for actuating the head over the disk;
- (d) a spindle motor for rotating the disk, the spindle motor comprising a plurality of windings;
- (e) an interface for receiving a supply voltage from the host computer;
- (f) a spindle driver for applying a current from the supply voltage to the windings of the spindle motor in response to a pulse width modulated (PWM) signal;
- (g) a current sensor for generating a current sense signal representing a current flowing from the supply voltage through at least the VCM and the windings of the spindle motor;
- (h) an integrator for integrating the current sense signal to generate an integration signal;
- and
- (i) a comparator for comparing the integration signal to a predetermined threshold, wherein an output of the comparator adjusts a duty cycle of the PWM signal.
A method of operating a disk drive connected to a host computer, the disk drive comprising a disk, a head, a voice coil motor (VCM) for actuating the head over the disk, and a spindle motor for rotating the disk, the spindle motor comprising a plurality of windings, the method comprising the steps of:
- (a) receiving a supply voltage from the host computer;
- (b) generating a pulse width modulated (PWM) signal;
- (c) applying a current from the supply voltage to the windings of the spindle motor in response to the PWM signal;
- (d) sensing a current flowing from the supply voltage through at least the VCM and the windings of the spindle motor to generate a current sense signal;
- (e) integrating the current sense signal to generate an integration signal;
- (f) comparing the integration signal to a predetermined threshold;
- and
- (g) adjusting a duty cycle of the PWM signal in response to the comparison.
Dependencies are inferred from the claim text.