Contamination mitigation cap for a hard disk drive actuator pivot assembly

A contamination mitigation cap for a hard disk drive actuator pivot assembly is affixed to the rotatable carriage of an actuator assembly and, in conjunction with a bearing hub cap, forms a labyrinth seal for retaining pivot bearing contamination. Consequently, the risk of such contamination migrating to the head-disk interface and causing read/write problems is mitigated, especially in the context of sleeveless pivot bearing assemblies. Various shapes of the contamination mitigation cap may be utilized, such as a flat ring, an S-section ring, and an L-section ring.

FIELD OF EMBODIMENTS

Embodiments of the invention may relate generally to hard disk drives and more particularly to a contamination mitigation cap for an actuator pivot assembly.

BACKGROUND

A hard-disk drive (HDD) is a non-volatile storage device that is housed in a protective enclosure and stores digitally encoded data on one or more circular disk having magnetic surfaces. When an HDD is in operation, each magnetic-recording disk is rapidly rotated by a spindle system. Data is read from and written to a magnetic-recording disk using a read/write head that is positioned over a specific location of a disk by an actuator. A read/write head uses a magnetic field to read data from and write data to the surface of a magnetic-recording disk. A write head makes use of the electricity flowing through a coil, which produces a magnetic field. Electrical pulses are sent to the write head, with different patterns of positive and negative currents. The current in the coil of the write head induces a magnetic field across the gap between the head and the magnetic disk, which in turn magnetizes a small area on the recording medium.

Because the actuator rotates to move across portions of the disk, the actuator includes a pivot assembly. The pivot assembly typically includes a pivot bearing assembly, such as a ball-bearing assembly. Because moving parts are involved, the pivot bearing assembly typically includes a lubricant, such as a hydrocarbon-based oil. Such a bearing assembly is typically not completely sealed and, therefore, some of the lubricant is known to exit the bearing assembly and can migrate to the head-disk interface (HDI) which can lead to read and/or write errors. Thus, minimizing the risk of contaminants from the pivot bearing reaching the HDI and causing operational errors is an ongoing challenge associated with hard disk drive design and development efforts.

SUMMARY OF EMBODIMENTS

Embodiments of the invention are directed toward an actuator contamination mitigation cap, a hard disk drive and corresponding actuator pivot assembly employing such a contamination mitigation cap, and a method for assembling an actuator pivot assembly utilizing such a contamination mitigation cap, where the contamination mitigation cap is affixed to the rotatable carriage of the actuator assembly and, in conjunction with a bearing hub cap, forms a labyrinth seal for retaining pivot bearing contamination. Consequently, the risk of such contamination migrating to the head-disk interface and causing read and/or write problems is mitigated.

Embodiments include various shapes of the contamination mitigation cap, such as a flat ring, an S-section ring, and an L-section ring. Additionally, the contamination mitigation cap may include a constituent pressure sensitive adhesive for bonding the cap to the carriage. For a non-limiting example, an actuator pivot assembly in which the type of contamination mitigation cap described herein is utilized is especially useful in the context of sleeveless pivot bearing assemblies.

Embodiments discussed in the Summary of Embodiments section are not meant to suggest, describe, or teach all the embodiments discussed herein. Thus, embodiments of the invention may contain additional or different features than those discussed in this section. Furthermore, no limitation, element, property, feature, advantage, attribute, or the like expressed in this section, which is not expressly recited in a claim, limits the scope of any claim in any way.

DETAILED DESCRIPTION

Approaches to an actuator contamination mitigation cap are described. In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the invention described herein. It will be apparent, however, that the embodiments of the invention described herein may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to avoid unnecessarily obscuring the embodiments of the invention described herein.

Physical Description of Illustrative Operating Environments

Embodiments may be used for mitigating contamination from an actuator in a hard disk drive (HDD) storage device. Thus, in accordance with an embodiment, a plan view illustrating an HDD100is shown inFIG. 1to illustrate an exemplary operating environment.

FIG. 1illustrates the functional arrangement of components of the HDD100including a slider110bthat includes a magnetic-reading/recording head110a. Collectively, slider110band head110amay be referred to as a head slider. The HDD100includes at least one head gimbal assembly (HGA)110including the head slider, a lead suspension110cattached to the head slider typically via a flexure, and a load beam110dattached to the lead suspension110c. The HDD100also includes at least one magnetic-recording medium120rotatably mounted on a spindle124and a drive motor (not visible) attached to the spindle124for rotating the medium120. The head110aincludes a write element and a read element for respectively writing and reading information stored on the medium120of the HDD100. The medium120or a plurality of disk media may be affixed to the spindle124with a disk clamp128.

The HDD100further includes an arm132attached to the HGA110, a carriage134, a voice-coil motor (VCM) that includes an armature136including a voice coil140attached to the carriage134and a stator144including a voice-coil magnet (not visible). The armature136of the VCM is attached to the carriage134and is configured to move the arm132and the HGA110, to access portions of the medium120, being mounted on a pivot-shaft148with an interposed pivot bearing assembly152. In the case of an HDD having multiple disks, the carriage134is called an “E-block,” or comb, because the carriage is arranged to carry a ganged array of arms that gives it the appearance of a comb.

An assembly comprising a head gimbal assembly (e.g., HGA110) including a flexure to which the head slider is coupled, an actuator arm (e.g., arm132) and/or load beam to which the flexure is coupled, and an actuator (e.g., the VCM) to which the actuator arm is coupled, may be collectively referred to as a head stack assembly (HSA). An HSA may, however, include more or fewer components than those described. For example, an HSA may refer to an assembly that further includes electrical interconnection components. Generally, an HSA is the assembly configured to move the head slider to access portions of the medium120for read and write operations.

With further reference toFIG. 1, electrical signals (e.g., current to the voice coil140of the VCM) comprising a write signal to and a read signal from the head110a, are provided by a flexible interconnect cable156(“flex cable”). Interconnection between the flex cable156and the head110amay be provided by an arm-electronics (AE) module160, which may have an on-board pre-amplifier for the read signal, as well as other read-channel and write-channel electronic components. The AE160may be attached to the carriage134as shown. The flex cable156is coupled to an electrical-connector block164, which provides electrical communication through electrical feedthroughs provided by an HDD housing168. The HDD housing168, also referred to as a base, in conjunction with an HDD cover provides a sealed, protective enclosure for the information storage components of the HDD100.

Other electronic components, including a disk controller and servo electronics including a digital-signal processor (DSP), provide electrical signals to the drive motor, the voice coil140of the VCM and the head110aof the HGA110. The electrical signal provided to the drive motor enables the drive motor to spin providing a torque to the spindle124which is in turn transmitted to the medium120that is affixed to the spindle124. As a result, the medium120spins in a direction172. The spinning medium120creates a cushion of air that acts as an air-bearing on which the air-bearing surface (ABS) of the slider110brides so that the slider110bflies above the surface of the medium120without making contact with a thin magnetic-recording layer in which information is recorded.

The electrical signal provided to the voice coil140of the VCM enables the head110aof the HGA110to access a track176on which information is recorded. Thus, the armature136of the VCM swings through an arc180, which enables the head110aof the HGA110to access various tracks on the medium120. Information is stored on the medium120in a plurality of radially nested tracks arranged in sectors on the medium120, such as sector184. Correspondingly, each track is composed of a plurality of sectored track portions (or “track sector”), for example, sectored track portion188. Each sectored track portion188may be composed of recorded data and a header containing a servo-burst-signal pattern, for example, an ABCD-servo-burst-signal pattern, which is information that identifies the track176, and error correction code information. In accessing the track176, the read element of the head110aof the HGA110reads the servo-burst-signal pattern which provides a position-error-signal (PES) to the servo electronics, which controls the electrical signal provided to the voice coil140of the VCM, enabling the head110ato follow the track176. Upon finding the track176and identifying a particular sectored track portion188, the head110aeither reads data from the track176or writes data to the track176depending on instructions received by the disk controller from an external agent, for example, a microprocessor of a computer system.

An HDD's electronic architecture comprises numerous electronic components for performing their respective functions for operation of an HDD, such as a hard disk controller (“HDC”), an interface controller, an arm electronics module, a data channel, a motor driver, a servo processor, buffer memory, etc. Two or more of such components may be combined on a single integrated circuit board referred to as a “system on a chip” (“SOC”). Several, if not all, of such electronic components are typically arranged on a printed circuit board that is coupled to the bottom side of an HDD, such as to HDD housing168.

References herein to a hard disk drive, such as HDD100illustrated and described in reference toFIG. 1, may encompass a data storage device that is at times referred to as a “hybrid drive”. A hybrid drive refers generally to a storage device having functionality of both a traditional HDD (see, e.g., HDD100) combined with solid-state storage device (SSD) using non-volatile memory, such as flash or other solid-state (e.g., integrated circuits) memory, which is electrically erasable and programmable. As operation, management and control of the different types of storage media typically differs, the solid-state portion of a hybrid drive may include its own corresponding controller functionality, which may be integrated into a single controller along with the HDD functionality. A hybrid drive may be architected and configured to operate and to utilize the solid-state portion in a number of ways, such as, for non-limiting examples, by using the solid-state memory as cache memory, for storing frequently-accessed data, for storing I/O intensive data, and the like. Further, a hybrid drive may be architected and configured essentially as two storage devices in a single enclosure, i.e., a traditional HDD and an SSD, with either one or multiple interfaces for host connection.

Introduction

As mentioned, the pivot bearing assembly typically includes a lubricant and because such a bearing assembly is typically not completely sealed, some of the lubricant is known to exit the bearing assembly and can migrate to the head-disk interface (HDI) which can lead to read and/or write errors. Thus, minimizing the risk of contaminants from the pivot bearing reaching the HDI and causing operational errors is an ongoing challenge associated with hard disk drive design and development efforts. Such challenges are especially pertinent with hard disk drives for enterprise applications, which have more stringent requirements for drive reliability.

One possible approach to minimizing the risk of hydrocarbons migrating from the pivot bearing to the HDI involves applying barrier films at critical locations along the migration path, which act as anti-wetting agents and inhibit the transport of lubricants. However, there can be significant tooling capital and process costs, and increased complexity, associated with such an approach. Furthermore, a containment approach may also be viable, i.e., by containing the lubricant at the pivot bearing assembly.

FIG. 2is a cross-sectional side view illustrating an HDD actuator pivot assembly, according to an embodiment. Actuator pivot assembly200comprises an actuator comb comprising a carriage202having a bore204therethrough. Actuator pivot assembly200further comprises a sleeveless pivot bearing assembly206disposed within the carriage bore204and a shaft208to which a circular ring-shaped hub cap210is attached. The hub cap210provides some degree of resistance to the outflow of lubricant (e.g., oil) from the pivot bearing. However, because the pivot bearing assembly206is a sleeveless assembly (at least in part due to space constraints and optimizations within an HDD), any approach involving the creation of a labyrinth seal in association with the hub cap210and such a bearing sleeve is not achievable.

Actuator Pivot Assembly Having a Contamination Mitigation Cap

FIG. 3Ais a cross-sectional side view illustrating an HDD actuator pivot assembly, according to an embodiment. Actuator pivot assembly300comprises a rotatable actuator comb comprising a carriage302having a bore304therethrough. Actuator pivot assembly300further comprises a pivot bearing assembly306(e.g., sleeveless) disposed within the carriage bore304and a shaft308to which a circular ring-shaped lower hub cap310is fixed. A typical pivot bearing assembly is composed of the shaft308, a spacer307, lower bearing309aand upper bearing309B, and the lower hub cap310.

Additionally, the actuator pivot assembly300comprises a contamination mitigation cap312bonded to the rotatable carriage302. The contamination mitigation cap312is configured, in positional relation with the lower hub cap310, to form a labyrinth for retaining contamination (e.g., lubricant, oil) from the pivot bearing assembly306. Thus, bearing oil would have to travel along a circuitous labyrinth313path in order to outflow from the actuator pivot assembly300and, therefore, is now less likely to be able to migrate over time and operational use, to the head-disk interface where it could otherwise cause significant operational problems. According to an embodiment, the contamination mitigation cap312is positioned above the lower hub cap310, to form the labyrinth.

Notably, the contamination mitigation cap312is bonded to the carriage302rather than to any part of the pivot bearing306, such as to a pivot bearing sleeve which is not present in the design of a sleeveless bearing such as pivot bearing assembly306. Use of a sleeveless pivot bearing can be beneficial in an HDD design as it consumes less internal space and provides for reduced cost and reduced inertia, which may lead to better actuator performance and thus better HDD performance than an HDD design in which a sleeved bearing is used. However, according to an embodiment, the pivot bearing assembly used in an actuator pivot assembly according to embodiments described herein may be a pivot bearing assembly comprising an outer sleeve, i.e., a sleeved pivot bearing assembly.

FIG. 3Bis a perspective view illustrating a contamination mitigation cap312, according to an embodiment. Contamination mitigation cap312is composed of a flat metal ring portion314, and a pressure sensitive adhesive (PSA)316around the outer edge of the contamination mitigation cap312for bonding the contamination mitigation cap312to a portion, i.e., a seat, of the carriage302. Use of a PSA may be beneficial in providing for removal of the contamination mitigation cap312, for example, for reworking a unit. Further, use of a PSA does not require curing and cleaning, such as with some other bonding adhesives.

According to an embodiment, the metal of flat metal ring portion314is a stainless steel material. One approach to the formation of the contamination mitigation cap312may be to stamp the metal to form the cap. However, the contamination mitigation cap312may be formed of a material other than metal, such as a synthetic or synthetic polymer material, for a non-limiting example, a plastic.

FIG. 4Ais a cross-sectional side view illustrating an HDD actuator pivot assembly, according to an embodiment. Actuator pivot assembly400comprises a rotatable actuator comb comprising a carriage402having a bore404therethrough. Actuator pivot assembly400further comprises a pivot bearing assembly306(e.g., sleeveless) disposed within the carriage bore404and a shaft308to which a circular ring-shaped lower hub cap310is fixed.

Additionally, the actuator pivot assembly400comprises a contamination mitigation cap412bonded to the rotatable carriage402. The contamination mitigation cap412is configured, in positional relation with the lower hub cap310, to form a labyrinth for retaining contamination (e.g., lubricant, oil) from the pivot bearing assembly306. Thus, bearing oil would have to travel along a circuitous labyrinth413path in order to outflow from the actuator pivot assembly400and, therefore, is now less likely to be able to migrate over time and operational use, to the head-disk interface where it could otherwise cause significant operational problems. According to an embodiment, the contamination mitigation cap412is positioned above the lower hub cap310, to form the labyrinth. Notably, the contamination mitigation cap412is bonded to the carriage402rather than to any part of the pivot bearing306, such as to a pivot bearing sleeve which is not present in the design of a sleeveless bearing such as pivot bearing assembly306.

FIG. 4Bis a perspective view illustrating a contamination mitigation cap, according to an embodiment. Contamination mitigation cap412is composed of a S-section (i.e., the cross-sectional shape roughly resembles the letter “S”, or perhaps the letter “Z”) metal ring portion314, substantially as depicted inFIGS. 4A and 4B, and a pressure sensitive adhesive (PSA)416around the upper outer edge of the contamination mitigation cap412for bonding the contamination mitigation cap412to a portion, i.e., a seat, of the carriage402. Use of a PSA may be beneficial in providing for removal of the contamination mitigation cap412, for example, for reworking a unit. Further, use of a PSA does not require curing and cleaning, such as with some other bonding adhesives.

According to an embodiment, the metal of the S-section metal ring portion414is a stainless steel material. One approach to the formation of the contamination mitigation cap312may be to stamp the metal to form the cap. However, the contamination mitigation cap312may be formed of a material other than metal, such as a synthetic or synthetic polymer material, for a non-limiting example, a plastic. The shape of the contamination mitigation cap412(FIGS. 4A,4B) provides for a chamfer for swaging purposes. Contamination mitigation cap412(FIGS. 4A,4B) has a more complex geometry and higher stiffness than the contamination mitigation cap312(FIGS. 3A,3B), but is also likely a little bit more costly.

FIG. 5Ais a cross-sectional side view illustrating an HDD actuator pivot assembly, according to an embodiment. Actuator pivot assembly500comprises a rotatable actuator comb comprising a carriage502having a bore504therethrough. Actuator pivot assembly500further comprises a pivot bearing assembly306(e.g., sleeveless) disposed within the carriage bore504and a shaft308to which a circular ring-shaped lower hub cap310is fixed.

Additionally, the actuator pivot assembly500comprises a contamination mitigation cap512bonded to the rotatable carriage502. The contamination mitigation cap512is configured, in positional relation with the lower hub cap310, to form a labyrinth for retaining contamination (e.g., lubricant, oil) from the pivot bearing assembly306. Thus, bearing oil would have to travel along a circuitous labyrinth path513in order to outflow from the actuator pivot assembly500and, therefore, is now less likely to be able to migrate over time and operational use, to the head-disk interface where it could otherwise cause significant operational problems. According to an embodiment, the contamination mitigation cap512is positioned above the lower hub cap310, to form the labyrinth. Notably, the contamination mitigation cap512is bonded to the carriage502rather than to any part of the pivot bearing306, such as to a pivot bearing sleeve which is not present in the design of a sleeveless bearing such as pivot bearing assembly306.

FIG. 5Bis a perspective view illustrating a contamination mitigation cap, according to an embodiment. Contamination mitigation cap512is composed of an L-section (i.e., the cross-sectional shape roughly resembles the letter “L”) metal ring portion514, substantially as depicted inFIGS. 5A and 5B, and a pressure sensitive adhesive (PSA)516around the upper outer edge of the contamination mitigation cap512for bonding the contamination mitigation cap512to a portion, i.e., a seat, of the carriage502. Use of a PSA may be beneficial in providing for removal of the contamination mitigation cap512, for example, for reworking a unit. Further, use of a PSA does not require curing and cleaning, such as with some other bonding adhesives.

According to an embodiment, the metal of the L-section metal ring portion514is a stainless steel material. One approach to the formation of the contamination mitigation cap312may be to stamp the metal to form the cap. However, the contamination mitigation cap312may be formed of a material other than metal, such as a synthetic or synthetic polymer material, for a non-limiting example, a plastic. The shape of the contamination mitigation cap512(FIGS. 5A,5B) provides for a chamfer for swaging purposes, and has a more complex geometry and higher stiffness than the contamination mitigation cap312(FIGS. 3A,3B), but is also likely a little bit more costly.

Method for Assembling a Hard Disk Drive Actuator Pivot Assembly

FIG. 6is a flow diagram illustrating a method for assembling an HDD actuator pivot assembly, according to an embodiment.

At block602, dispose a pivot bearing assembly into a rotatable carriage bore of an actuator comb, wherein the pivot bearing assembly comprises a stationary shaft to which a lower hub cap is fixed.

For example, pivot bearing assembly306(FIGS. 3A,4A,5A) is disposed into carriage bore304,404,504(FIGS. 3A,4A,5A, respectively) of carriage302,402,502(FIGS. 3A,4A,5A, respectively), where the pivot bearing assembly306includes stationary shaft308to which a lower hub cap310(FIGS. 3A,4A,5A) is fixed. Pivot bearing assemblies such as pivot bearing assembly306may be press-fit into a carriage bore such as carriage bore304,404,504of carriage302,402,502. While pivot bearing assembly306is depicted as, and according to an embodiment is, a sleeveless bearing assembly, the method ofFIG. 6could also apply to the use of a sleeved pivot bearing assembly.

At block604, a contamination mitigation cap is affixed to the carriage, wherein the contamination mitigation cap is positioned relative to the lower hub cap to form a labyrinth, for retaining contamination from the pivot bearing assembly.

For example, contamination mitigation cap312,412,512(FIGS. 3A,4A,5A, respectively) is bonded or press-fit, for non-limiting example, to the carriage302,402,502(FIGS. 3A,4A,5A, respectively), where the contamination mitigation cap312,412,512is positioned relative to lower hub cap310(FIGS. 3A,4A,5A) to form a labyrinth313,413,513(FIGS. 3A,4A,5A, respectively) path to mitigate the outflow and migration of contaminants from the pivot bearing assembly306(FIGS. 3A,4A,5A).

Extensions and Alternatives

In the foregoing description, embodiments of the invention have been described with reference to numerous specific details that may vary from implementation to implementation. Therefore, various modifications and changes may be made thereto without departing from the broader spirit and scope of the embodiments. Thus, the sole and exclusive indicator of what is the invention, and is intended by the applicants to be the invention, is the set of claims that issue from this application, in the specific form in which such claims issue, including any subsequent correction. Any definitions expressly set forth herein for terms contained in such claims shall govern the meaning of such terms as used in the claims. Hence, no limitation, element, property, feature, advantage or attribute that is not expressly recited in a claim should limit the scope of such claim in any way. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.

In addition, in this description certain process steps may be set forth in a particular order, and alphabetic and alphanumeric labels may be used to identify certain steps. Unless specifically stated in the description, embodiments are not necessarily limited to any particular order of carrying out such steps. In particular, the labels are used merely for convenient identification of steps, and are not intended to specify or require a particular order of carrying out such steps.