Western Digital Technologies, Inc.

Robert J McNab

Hemant Melkote

Yih-Jen Dennis Chen

Jack M Chue

Lin Yang

Jai N Subrahmanyam

David D Nguyen

Mukesh Patel

Rasool Koosha

Siri S Weerasooriya

Jin Hui Ou-Yang

Zhi Ning Wang

Min Chen

Chiao-Ping (Roger) Ku

Thomas J Hitchner

Jung-Seo Park

Daniel T Nguyen

Shuo-Hao Chen

Siddhesh Vivek Sakhalkar

Antony Nguyen

Jen-Tai Lin

John Yin Kwong Li

Li Yi

William C Tipton, Ii

Yanbin Song

Lin Mei

Arafat M Butt

Jiasheng Zhu

Jenghung Cheng

David A Spaulding

John Bianchini

A hard disk drive includes multiple disk media mounted on a spindle, where the outer diameter of each disk medium is offset from the inner diameter of the disk medium in a same direction along an axis of rotation of the spindle, and a load/unload ramp positioned, based on the offset, to align in correspondence with the outer diameters of the disk media. Thus, the curvature of irregular disk media, such as that associated with thinner and thinner disks, is mitigated by grouping similarly-characterized irregular disks together on a given spindle and compensating the ramp accordingly.

Hard disk drive disk media curvature mitigation

A multi-actuator hard disk drive includes a lower actuator with a corresponding voice coil motor assembly (VCMA), a coaxial upper actuator with a corresponding VCMA, and a central support plate positioned between the upper and lower VCMAs and to which the upper VCMA is fastened. Use of a central support plate enables some control over the direct and coupled plant transfer functions, while effectively providing a base support structure for the upper VCMA and enabling use of conventionally-sized fasteners.

Center structure having attachment support for an actuator in a multi-actuator hard disk drive

A disk spindle assembly for a hard disk drive includes a hub and a hub flange extending radially from the hub and configured to apply a clamping force to secure disk media to the hub. The hub flange includes multiple protrusions extending from a surface of a top side and configured to contact a disk medium at multiple contact positions in response to application of a clamping load. The protrusions may be annular protrusions circumscribing the hub, where the height of an inner protrusion may be less than the height of an outer protrusion to inhibit coning of the bottom disk medium, and the protrusions may be positioned so that an equivalent contact radius corresponding to contact radii of the inner and outer annular protrusions is at a position halfway between the inner and outer diameters of the disk spacers to inhibit coning of the middle disk media.

Hard disk drive multiple contact disk spindle motor hub flange

A disk clamp for a hard disk drive, configured to clamp disk media to a spindle, includes multiple protrusions extending from a surface of a bottom side and configured to contact a disk medium at multiple contact positions in response to application of a clamping load. The protrusions may be annular protrusions circumscribing a disk clamp hub, where the height of an inner protrusion may be less than the height of an outer protrusion to inhibit coning of the top disk medium, and the protrusions may be positioned so that an equivalent contact radius corresponding to contact radii of the inner and outer annular protrusions is at a position halfway between the inner and outer diameters of the disk spacers to inhibit coning of the middle disk media.

Hard disk drive multiple contact disk clamp

An apparatus for peripherally encapsulating a plurality of piezoelectric elements includes a first fixture with a fixture base and a plurality of protrusions extending from the fixture base. Each protrusion includes a distal support surface that is approximately the same size as an exposed portion of a first side of each of the plurality of piezoelectric elements. The apparatus includes first and second alignment combs, each including a plurality of tines that are spaced to position each of the plurality of piezoelectric elements there between. The tines of the second alignment comb are oriented approximately orthogonally relative to the tines of the first alignment comb.

Apparatus for manufacturing piezoelectric actuators

A method of manufacturing a microactuator. The method includes providing a sheet of a piezoelectric material having an electrically conductive layer on at least one side of the sheet. The method includes cutting the sheet to form a plurality of piezoelectric elements. Each of the piezoelectric elements includes a first element side with an electrically conductive layer. Each first element side includes a peripheral portion and an exposed portion interior to the peripheral portion. The method includes forming an encapsulation layer over the peripheral portion and not over the exposed portion of at least one of the sides. The encapsulation layer comprises a material of lesser electrical conductivity than the electrically conductive layer. An apparatus for manufacturing the microactuators may also be provided that includes a first fixture and first and second alignment combs.

Method for manufacturing a disk drive microactuator that includes a piezoelectric element and a peripheral encapsulation layer

A method is disclosed for efficiently determining and writing repeatable runout (RRO) compensation value sets for data tracks on a magnetic disk in a disk drive. The disk drive has a magnetoresistive (MR) head having a read element and a separate write element, and a secondary actuator coupled to the end of a primary actuator for adjusting a head skew angle. In the method, the head skew angle is set such that the read and write elements are substantially aligned along the first track. A position error signal for each servo sector is determined over a predetermined number of disk revolutions during track following along a first data track. An RRO compensation value set is calculated for the first data track based on the position error signals. The RRO compensation value set is written for the first data track. A seek operation is then performed to a second data track.

Magnetic disk drive and method for efficiently determining and storing RRO compensation values using a secondary micro-actuator

A method of servo writing a plurality of servo sectors to a disk of a disk drive to define a plurality of data tracks is disclosed. The disk drive comprises the disk, an actuator arm, a head coupled to a distal end of the actuator arm, wherein the head comprises a read element and a write element. A voice coil motor (VCM) rotates the actuator arm about a pivot to actuate the head radially over the disk, and a secondary actuator adjusts a skew angle for the head while using the write element to write the servo sectors to the disk.

Servo writing a disk drive using a secondary actuator to control skew angle

A disk drive includes a disk drive base, a disk, and a head stack assembly rotatably coupled to the base adjacent the disk surface of the disk. The disk drive includes an airflow channeling enclosure. The enclosure includes an airflow inlet disposed downstream of the head stack assembly and configured to receive the disk rotation induced airflow therethrough. The enclosure further includes an airflow channel extending along the disk surface from the airflow inlet. The enclosure further includes an outer wall extending along the disk surface from the airflow inlet and defining the airflow channel radially interior to the outer wall. The enclosure further includes an airflow outlet disposed upstream of the head stack assembly extending from the outer wall and the channel opposite the airflow inlet for modifying the disk rotation induced airflow passing from the channel.

Disk drive with airflow channeling enclosure

A method is disclosed for writing repeatable runout (RRO) correction values to a disk of a disk drive. The disk has distributed position information in a plurality of embedded servo sectors. The transducer head has a read element that is offset from a write element. The write element is positioned over a target track while the distributed position information from a followed track is read using the read element. The target track is different from the followed track due to the offset between the read element and the write element. Previously determined RRO correction values associated with the target track are written at radial positions on the target track. The radial positions are based on the distributed position information of the followed track, previously determined RRO correction values associated with the followed track, and a portion of the previously determined RRO correction values associated with the target track.

Method for writing repeatable runout correction values to a magnetic disk of a disk drive

Servo writing a disk of a disk drive is disclosed. A phase locked loop (PLL) is synchronized to first sectors previously written on a first track, and second sectors are written to a second track using the PLL, wherein a plurality of phase errors corresponding to the second sectors are saved. A correction value is computed corresponding to a selected one of the second sectors, wherein the correction value is computed in response to a plurality of the phase errors generated for a plurality of the second sectors leading the selected sector. The PLL is synchronized to the second sectors using the correction value, a third sector is written to a third track using the PLL, and a phase error is saved corresponding to the third sector.

Servo writing a disk drive using correction values that attenuate phase error propagation

A suspension assembly includes a load beam, a mount plate, first and second piezoelectric microactuators, and a flex circuit segment. The first piezoelectric microactuator is electrically non-conductively attached to the load beam and the mount plate. The first piezoelectric microactuator includes a first piezoelectric element, a first top electrode, and a first bottom electrode. The second piezoelectric microactuator is electrically non-conductively attached to the load beam and the mount plate. The second piezoelectric microactuator includes a second piezoelectric element, a second top electrode, and a second bottom electrode. The flex circuit segment is disposed folded about the first and second piezoelectric microactuators. The flex circuit segment is in electrical communication with the first top electrode, the first bottom electrode, the second top electrode, and the second bottom electrode.

Suspension assembly with piezoelectric microactuators electrically connected to a folded flex circuit segment

A method of operating a disk drive including providing the disk drive. The disk drive includes a disk with data tracks and an actuator with a slider including a perpendicular magnetic write head. The write head includes leading and trailing sides defining a taper angle. The write head and the actuator define a maximum skew angle with respect to the data tracks. The maximum skew angle being greater than the taper angle. The method further includes rotating the slider during operation of the disk drive to reduce a difference between the skew and taper angles for aligning the write head with the data tracks.

Method of operating a disk drive including rotating a perpendicular write head to reduce a difference between skew and taper angles, and a disk drive

A magnetic disk drive having a reduction in repeatable runout (RRO) effects is disclosed. The disk drive has a head disk assembly (HDA) and a sampled servo controller. The HDA includes a rotating magnetic disk, an actuator, and a transducer head. The magnetic disk has a plurality of embedded servo sectors for storing servo information including repeatable runout (RRO) cancellation values and RRO cancellation value error correction code (ECC) data at a servo data rate. The RRO cancellation value ECC data is only for detecting and correcting errors in the RRO cancellation values. In between the embedded servo sectors are data sectors for storing user data at a user data rate that is different from the servo data rate. The actuator positions the transducer head in response to a control effort signal generated by the sampled servo controller based on the servo information.

Disk drive having servo sectors that store repeatable runout correction values and related error correction code data

A disk drive is disclosed employing a primary actuator for rotating an actuator arm about a pivot in coarse movements, and first and second secondary actuators coupled to the actuator arm for actuating first and second heads in fine movements. A servo control system generates a first control signal applied to the first secondary actuator to position the first head over the first disk surface in fine movements while accessing the first disk surface. The servo control system phase shifts the first control signal by a predetermined phase to generate a second control signal applied to the second secondary actuator to attenuate excitation of at least one arm vibration mode.

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San Jose, CA, United States of America

Robert J McNab