Western Digital Technologies, Inc.

Hideaki Ito

Gaku Ikedo

Jaesoo Byoun

Naoyuki Kagami

Brian A Johnson

Brian Johnson

Hiroki Watanabe

Hajime Eguchi

Christopher David Wiederholt

Shravankumar Girish Bhat

Yasunori Fukuyama

A data storage device may include an outer fine actuator group, an inner fine actuator group, and control circuitry comprising: a slew control voltage generator, a first switch, and a second switch. The control circuitry is configured to: generate a control signal; control the first switch to apply the control signal to a first fine actuator group for a first duration; control the first switch to apply the control signal to a second fine actuator group for a second duration, wherein each of the first and the second fine actuator groups comprises one of the inner or the outer fine actuator groups, and wherein the first and second fine actuator group are different; concurrently discharge the first fine actuator group during the second duration, based at least in part on controlling the second switch to couple the first fine actuator group to the slew control voltage generator.

Voltage slew control of fine actuators during discharge

A data storage device comprises a lead actuator that actuates a first read-write head over a first disk and a support actuator that actuates a second read-write head over a second disk. A spindle motor rotates the first and second disks. In response to an emergency power off (EPO) event, a processing device retracts and parks the actuators using an internal supply voltage generated from a back electromotive force (BEMF) voltage of the spindle motor, and brakes the spindle motor. The spindle motor is not braked until both the lead and support actuators have been retracted and parked.

Data storage device having dual actuators and method for emergency power off retract (EPOR) of dual actuators

Various illustrative aspects are directed to a data storage device comprising one or more disks, an actuator arm assembly comprising one or more disk heads and a voice coil motor (VCM), the VCM configured to operate in a PWM mode and a linear mode, and one or more processing devices configured to: seek the VCM towards a target track in the PWM mode; transition the VCM from the PWM mode to the linear mode, wherein the transitioning comprises switching an offset compensation value from a first offset compensation value to a second compensation offset value to compensate for a transition offset induced while transitioning the VCM from the PWM to the linear mode, wherein the first and the second offset compensation values correspond to the PWM and linear modes, respectively, and seek the VCM towards the target track in the linear mode for a linear mode time.

VCM PWM to linear mode transition offset optimization to improve PES

A data storage device has a closed loop extended park mode during spin down operation. A data storage device comprises a spindle motor configured to rotate one or more disks, and one or more processing devices. The one or more processing devices are configured to determine a value of current that is discharged from the spindle motor over time during a spin down of the spindle motor, and control a braking duty cycle for braking the spindle motor during the spin down such that the value of current discharged from the spindle motor over time does not exceed a selected current limit.

Data storage device with closed loop extended park mode during spin down operation

Various illustrative aspects are directed to a data storage device comprising one or more disks, an actuator arm assembly comprising a voice coil motor (VCM), the VCM configured to operate in a first mode and a second, different mode, wherein the first mode corresponds to at least a first and a second setting, and a control circuitry configured to cause the VCM to seek towards a target track in the first mode using the first setting for a first duration, control transition of the VCM from the first to the second setting in the first mode, cause the VCM to seek towards the target track using the second setting for a second duration, and control transition of the VCM from the first to a second mode, wherein controlling the transitioning comprises seeking the VCM toward the target track in the second mode for a third duration.

Optimize power, RTV, and coupled PES during seek operations

Various illustrative aspects are directed to a data storage device comprising a disk and a spindle motor configured to rotate the disk wherein the spindle motor is powered by a drive voltage generated in response to a host voltage. The data storage device includes a head configured to be actuated over the disk by a head actuator and control circuitry comprising an isolation field effect transistor (ISOFET) configured to prevent a reverse current from flowing from the drive voltage to the host voltage when the host voltage falls below a threshold. The control circuitry sets a turnoff current level at which the ISOFET is directed to turn off to prevent the reverse current from flowing determines a drain-source on resistance Rdson of the ISOFET, and calculates a voltage turnoff threshold at which the ISOFET is turned off from the turnoff current level and the determined Rdson.

Data storage device with smart ISOFET threshold voltage automatic tuning

A data storage device comprises a lead actuator that actuates a first read-write head over a first disk and a support actuator that actuates a second read-write head over a second disk. A spindle motor rotates the first and second disks. In response to an emergency power off (EPO) event, a processing device retracts and parks the actuators using an internal supply voltage generated from a back electromotive force (BEMF) voltage of the spindle motor, and egresses data from a volatile to a non-volatile semiconductor memory. Egress is throttled before the actuators are retracted and parked when the internal supply voltage falls to or below a first egress throttling threshold voltage. Egress is throttled after the actuators are retracted and parked when the internal supply voltage falls to or below a second egress throttling threshold voltage.

Data storage device having dual actuators and method for data egress throttling during emergency power off retract (EPOR)

Various illustrative aspects are directed to a data storage device comprising a first spindle motor configured to rotate one or more disks in a first stack of disks, a second spindle motor configured to rotate one or more disks in a second stack of disks, and one or more processing devices configured to detect back electromotive force (BEMF) voltages generated by the first spindle motor and the second spindle motor. In other aspects the one or more processing devices can control speeds of the first spindle motor and the second spindle motor based on the detected BEMF voltages.

Dual spindle motors and dual spindle motor control for data storage

Various illustrative aspects are directed to a data storage device comprising one or more disks; an actuator arm assembly comprising one or more actuator arms, and configured to position the one or more actuator arms over disk surfaces of the one or more disks; one or more fine actuators, disposed on the one or more actuator arms; and one or more processing devices. The one or more processing devices are configured to: output a driver current to the one or more fine actuators, wherein the one or more processing devices are configured to rate limit a rise of the driver current over time during an activation of the driver current to within a selected rate limit of current rise over time.

Data storage device with soft on-disk activation of fine actuators

Example systems, data storage devices, and methods to provide data protection during concurrent operations for multiple actuator data storage devices are described. The data storage device includes a plurality of actuators configured to actuate a plurality of heads over different subsets of a plurality of disk surfaces. Responsive to receiving a write command for one of the actuators, the coupling state with at least one other of the actuators is determined and execution of write commands is inhibited if the coupling state indicates a possible coupling event. The inhibit of the write commands in the presence of coupling events may prevent off-track writes and protect data.

Data protection during concurrent operations for multiple actuator data storage devices

A data storage device is disclosed comprising a spindle motor configured to rotate a disk, and a first voice coil motor (VCM) configured to actuate a head over the disk. During at least fifty percent of a seek of the head over the disk, a spindle control signal is generated based on a continuous function of a current flowing through the first VCM, and the spindle control signal is applied to the spindle motor.

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Fujisawa, Japan

Hideaki Ito