US 12,254,909 B2Granted

VCM PWM to linear mode transition offset optimization to improve PES

AssigneeWestern Digital Technologies, Inc.

InventorsJaesoo Byoun, Brian Johnson, Hideaki Ito, Gaku Ikedo, Naoyuki Kagami

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Abstract

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.

Claims20

Dependent claims

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 first mode and a second mode, the first mode and the second mode each comprising one of a pulse width modulation (PWM) mode and a linear or current control loop (CCL) mode, the first mode being different from the second mode;
and
one or more processing devices or components, configured, individually or in combination, to:
perform a calibration routine, wherein performing the calibration routine comprises:
identifying a mapping between offset compensation values and a track arrival position error signal (PES), wherein each offset compensation value translates to a current offset applied to the VCM in the first mode or the second mode;
and wherein the mapping is identified by one or more of:
measuring the track arrival PES for one or more of different seek lengths and different directions, the directions selected from a group consisting of an inner diameter (ID) to an outer diameter (OD) direction and an OD to ID direction;
measuring the track arrival PES for different offset compensation values after seek completion;
and
incrementally reducing a linear mode time and measuring a corresponding track arrival PES.

8 more elements

A method of operating a data storage device, comprising:

performing a calibration routine to identify a mapping between offset compensation values and a track arrival position error signal (PES) for a voice coil motor (VCM) of the data storage device, wherein the VCM is configured to operate in a pulse width modulation (PWM) mode and a linear or current control loop (CCL) mode, and wherein identifying the mapping comprises at least:
measuring the track arrival PES for one or more of different seek lengths and different directions, the directions selected from a group consisting of an inner diameter (ID) to an outer diameter (OD) direction and an OD to ID direction;
measuring the track arrival PES for different compensation values after seek completion;
and
incrementally reducing a linear mode time and measuring a corresponding track arrival PES.

2 more elements

One or more processing devices or components configured, individually or in combination, to optimize power consumption in a data storage device, the one or more processing devices or components comprising:

means for performing a calibration routine, wherein the means for performing the calibration routine comprises:
means for identifying a mapping between offset compensation values and a track arrival position error signal (PES) for a voice coil motor (VCM) of the data storage device, wherein the VCM is configured to operate in a pulse width modulation (PWM) mode and a linear or current control loop (CCL) mode, and wherein the means for identifying the mapping comprises:
means for measuring the track arrival PES for one or more of different seek lengths and different directions, the directions selected from a group consisting of an inner diameter (ID) to an outer diameter (OD) direction and an OD to ID direction;
means for measuring the track arrival PES for different offset compensation values after seek completion;
and
means for incrementally reducing a linear mode time and measuring a corresponding track arrival PES.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 18/446,612Filed 9 Aug 2023 · division
Priority: 11 May 2022
Published: US 2023/0386512 A130 Nov 2023
Granted: 18 Mar 2025
Term ends: Not estimatedThe source records don’t support an estimate.

Classification3 codes

G11B 5/5547
Details: "Seek" control and circuits therefor
G11B 5/5543
Initialisation, calibration, e.g. cylinder "set-up": servo-format therefor
G11B
Information storage based on relative movement between record carrier and transducer