In-situ placement of cross-flux magnets in voice coil motor actuators

Abstract

The process of assembling a voice coil motor (VCM), such as for a hard disk drive, involves creating an opening in a yoke, attaching a primary magnet to the inside surface of the yoke, installing a cross flux magnet through the opening in the yoke and into the channel of the primary magnet, and installing a plug into the opening in the yoke, thus minimizing part count and making the manufacturing process easily integrated into existing VCM manufacturing processes.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Non-provisional Application No. 18 / 224,398, entitled "IN-SITU INSTALL OF CROSS-FLUX MAGNET IN VOICE COIL MOTOR ACTUATOR," filed with the United States Patent & Trademark Office on July 20, 2023, which claims priority to U.S. Provisional Application No. 63 / 435,405, filed on December 27, 2022, the entire contents of which are incorporated herein by reference for all purposes.

[0002] FIELD OF THE DISCLOSURE Embodiments of the present invention relate generally to voice coil motors, and more particularly to hard disk drive rotary voice coil actuators having crossed flux magnets mounted through a primary magnet housing. [Background technology]

[0003] A hard disk drive (HDD) is a non-volatile storage device that stores digitally encoded data on one or more circular disks that are housed in a protective enclosure and have 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 the magnetic recording disks using a read-write head (or "transducer") housed on a slider that is positioned over specific locations on the disks by an actuator. The read-write head uses a magnetic field to write data to and read data from the surface of the magnetic recording disk. The write head works by generating a magnetic field using an electric current that flows through a coil in the write head. Electrical pulses are sent to the write head with different patterns of positive and negative currents. The electric current in the coil in the write head creates a localized magnetic field across the gap between the head and the magnetic recording disk, thereby magnetizing small areas on the recording medium.

[0004] Typically, a voice coil motor ("VCM") is a type of actuator employed in HDDs to move a read-write head to access a portion of a corresponding magnetic recording disk for read and write operations. VCMs rely on permanent magnets for their own persistent magnetic field. Such a magnetic field is typically strongest at the magnet surface and decreases with distance therefrom, and thus the magnetic flux density decreases with distance from the magnet as well. Additionally, the cost of permanent magnets is typically proportional to the corresponding grade of magnet and the material from which the magnet is made, with higher grades indicating stronger magnets. Increasing areal density (a measure of the amount of information bits that can be stored on a given area of ​​the disk surface) is one of the ongoing goals of hard disk drive technology evolution. Given the trend toward higher areal density in HDDs, performance improvements to VCMs may be desirable.

[0005] The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Thus, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section. [Brief description of the drawings]

[0006] Embodiments are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings in which like reference numbers refer to similar elements and in which: [Figure 1] FIG. 1 is a plan view of a hard disk drive (HDD) according to one embodiment. [Diagram 2] FIG. 1 is a perspective view of an improved voice coil motor (VCM) assembly with crossed flux magnets according to one embodiment. [Figure 3A] FIG. 3 is a perspective view of a half-assembly of the improved VCM assembly of FIG. 2, according to one embodiment. [Figure 3B] FIG. 3B is a front view of a half assembly of the improved VCM assembly of FIG. 3A in accordance with one embodiment. [Figure 3C] FIG. 3B is a top view of a half assembly of the improved VCM assembly of FIG. 3A in accordance with one embodiment. [Figure 3D] FIG. 3B is a bottom view of a half assembly of the improved VCM assembly of FIG. 3A in accordance with one embodiment. [Figure 4A] FIG. 3B is a perspective view showing a first stage of an assembly process for a half-assembly of the improved VCM assembly of FIG. 3A in accordance with one embodiment. [Figure 4B] FIG. 3B is a perspective view showing a second stage of the assembly process for a half-assembly of the improved VCM assembly of FIG. 3A in accordance with one embodiment. [Figure 4C] FIG. 3B is a perspective view showing a third stage of the assembly process for a half-assembly of the improved VCM assembly of FIG. 3A in accordance with one embodiment. [Figure 4D]FIG. 3B is a perspective view showing a fourth stage of the assembly process for a half-assembly of the improved VCM assembly of FIG. 3A in accordance with one embodiment. [Figure 4E] FIG. 3B is a bottom perspective view showing a fourth stage of the assembly process for a half-assembly of the improved VCM assembly of FIG. 3A in accordance with one embodiment. [Figure 4F] FIG. 3B is a perspective view showing a fifth stage of the assembly process for a half-assembly of the improved VCM assembly of FIG. 3A in accordance with one embodiment. [Diagram 5] FIG. 1 is a flow diagram illustrating a method for assembling a VCM assembly with crossed flux magnets, according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Generally, an approach to an improved voice coil motor (VCM) assembly with crossed flux magnets, such as those used in hard disk drives (HDDs), is described. In the following description, for 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.

[0008] Introduction term References herein to "an embodiment," "one embodiment," or the like are intended to mean that the particular feature, structure, or characteristic being described is included in at least one embodiment of the invention. However, instances of such phrases do not necessarily all refer to the same embodiment.

[0009] It will be understood that the term "substantially" describes features that are largely or approximately structured, largely or approximately configured, largely or approximately dimensioned, etc., but that manufacturing tolerances and the like may result in situations where in practice the structure, configuration, dimensions, etc. are not always or necessarily precisely as described. For example, if one were to describe a structure as being "substantially vertical," the term would be assigned its obvious meaning, such that the sidewalls are for all practical purposes vertical, but may not be at exactly 90 degrees throughout.

[0010] Terms such as "optimal," "optimize," "minimal," "minimize," "maximal," "maximize," and the like may not have a specific value associated with them, but as such terms are used herein, those of skill in the art are intended to understand that such terms include influencing values, parameters, metrics, and the like in a beneficial direction consistent with the entirety of this disclosure. For example, describing some value as "minimum" does not require that the value actually be equal to a theoretical minimum (e.g., zero), but should be understood in a practical sense in that the corresponding goal would be to move the value in a beneficial direction toward the theoretical minimum.

[0011] context Recall the observation that performance improvements to VCMs may be desirable. The torque generated in a VCM is proportional to the magnetic flux density generated by the corresponding permanent magnet in that motor efficiency increases as the magnetic flux density increases. Thus, the higher the magnetic field gradient generated by the permanent magnet, the more efficiently the VCM is likely to operate. However, because HDDs are very space-constrained, the available approaches to building better VCMs are similarly limited.

[0012] Open-mounted Halbach-type voice coil motor 2 is a perspective view of an improved voice coil motor (VCM) assembly with crossed flux magnets, according to one embodiment. The VCM assembly 200 ("VCM200") includes a first magnet assembly 202a and a second magnet assembly 202b coupled to one another. For example, the first primary magnet assembly 202a and the second primary magnet assembly 202b may be joined together or may be manufactured as an integral assembly.

[0013] The first magnet assembly 202a comprises a first primary permanent magnet 204a magnetized to have a magnetic north pole 204a-n (N) and an adjacent magnetic south pole 204a-s (S) on each side of a first boundary and is coupled to a corresponding first yoke 206a. The first yoke 206a includes an opening 206a-o therethrough, the opening being plugged by a first plug 206a-p. According to one embodiment, the first yoke 206a and the first plug 206a-p are constructed of the same material, such as, for example, stainless steel. In particular, the first magnet assembly 202a further comprises a first cross-flux magnet 205a embedded and coupled into the first primary magnet 204a through the opening 206a-o in the first yoke 206a. According to an embodiment, the first cross-flux magnet 205a is embedded in a pre-formed channel or groove (see, e.g., FIGS. 4B-4C) in the first primary magnet 204a and extends from a proximal side (yoke 206a side) or surface of the first primary magnet 204a toward, but not all the way to, the distal side (air gap side) or surface of the first primary magnet 204a, and extends from a front side or surface of the first primary magnet 204a to a rear side or surface of the first primary magnet 204a. The first cross-flux magnet 205a is magnetized in a direction that is substantially perpendicular (i.e., perpendicular) to the direction of the N / S poles 204a-n, 204a-s (here, e.g., N to S direction), thus forming what is referred to as a Halbach array. In general, a Halbach array is a special arrangement of permanent magnets that has a spatially rotating magnetization pattern that enhances the magnetic field (e.g., strengthens the magnetic flux) on one side of the array while canceling the magnetic field to near zero (e.g., cancels the magnetic flux) on the other side.

[0014] Here, this Halbach array effect is made possible by the embedded, appropriately magnetized first cross-flux magnet 205a being embedded within and between the N / S poles 204a-n, 204a-s (i.e., substantially at the first boundary between the N / S poles 204a-n, 204a-s). This arrangement and in-situ assembly technique, made possible by the use of openings 206a-o through the first yoke 206a, where the first cross-flux magnet 205a is inserted into the first primary magnet 204a and plugged with first plugs 206a-p, results in an improvement over the classic Halbach array (compared to a compound magnet or other form of Halbach array assembly fabricated external to the first magnet assembly 202a) requiring fewer total components, greatly reducing manufacturing complexity at the expense of a small amount of optimization.

[0015] Similarly, the second magnet assembly 202b comprises a second primary permanent magnet 204b magnetized to have a magnetic north pole 204b-n (N) and an adjacent magnetic south pole 204b-s (S) on each side of a second boundary and is joined to a corresponding second yoke 206b. The second yoke 206b includes an opening 206b-o (not shown, see e.g., FIG. 4A) therethrough, which is plugged with a second plug 206b-p (not shown, see e.g., FIG. 3D, FIG. 4F). According to one embodiment, the second yoke 206b and the second plug 206b-p are constructed of the same material, such as, for example, stainless steel. Again, the second magnet assembly 202b further comprises a second cross-flux magnet 205b embedded in and joined to the second primary magnet 204b through the opening 206b-o in the second yoke 206b. According to an embodiment, the second cross-flux magnet 205b is embedded in a pre-formed channel or groove (see, for example, channels 204b-c in FIGS. 4B-4C) in the second primary magnet 204b and extends from a proximal side (yoke 206b side) or surface of the second primary magnet 204b toward, but not to, a distal side (air gap side) or surface of the second primary magnet 204b, and extends from a front side or surface of the second primary magnet 204b to a rear side or surface of the second primary magnet 204b. The second cross-flux magnet 205b is magnetized in a direction substantially perpendicular to the direction of the N / S poles 204b-n, 204b-s (here, for example, in a S to N direction), thus forming a Halbach array. Again, this Halbach array effect is made possible by the embedded, appropriately magnetized second crossed flux magnet 205b being embedded within and between the N / S poles 204b-n, 204b-s (i.e., substantially at the first boundary between the N / S poles 204b-n, 204b-s), resulting in the Halbach array requiring fewer total components and reducing manufacturing complexity.

[0016] It should be noted that while the first and second primary magnets 204a and 204b are shown in this section and throughout the specification with portions magnetized in specific directions for illustrative purposes (i.e., N / S poles 204a-n, 204a-s, and N / S poles 204b-n, 204b-s), the direction in which each pole 204a-n, 204a-s, 204b-n, 204b-s is magnetized may vary from implementation to implementation. For example, the poles shown as poles 204a-n and 204b-n may actually be magnetized in the S direction, while the poles shown as poles 204a-s and 204b-s may actually be magnetized in the N direction. Similarly, while the first and second cross flux magnets 205a, 205b are shown magnetized in a particular direction for illustrative purposes, the direction in which each cross flux magnet 205a, 205b is magnetized may vary from implementation to implementation, and thus each may be magnetized in the opposite direction to that shown here, so long as each is magnetized in a direction substantially perpendicular to the direction of the north / south poles 204a-n, 204a-s, 204b-n, 204b-s. Additionally, a complete VCM assembly may be implemented with only one half assembly (e.g., magnet assembly 202a or 202b) configured in a Halbach array arrangement with a corresponding embedded cross flux magnet (e.g., cross flux magnet 205a or 205b), while the opposing cooperating VCM half assembly is configured conventionally, i.e., without a Halbach array arrangement with embedded cross flux magnets.

[0017] FIGURE 3A is a perspective view of a half assembly of the improved VCM assembly of FIGURE 2, FIGURE 3B is a front view of the half assembly of the improved VCM assembly of FIGURE 3A, FIGURE 3C is a top view of the half assembly of the improved VCM assembly of FIGURE 3A, and FIGURE 3D is a bottom view of the half assembly of the improved VCM assembly of FIGURE 3A, all according to one embodiment. As mentioned above, FIGURES 3A-3D are additional views of the half assembly of the improved VCM assembly of FIGURE 2 to further show details of the second magnet assembly 202b. According to one embodiment, multiple half assemblies may be manufactured in this same configuration and then combined with another such half assembly to form a VCM magnet assembly, such as VCM assembly 200 (FIGURE 2).

[0018] Collectively, Figures 3A-3D show a second magnet assembly 202b comprising a second primary permanent magnet 204b magnetized to have a magnetic north pole 204b-n (N) and an adjacent magnetic south pole 204b-s (S) on each side of a boundary 207 and bonded or otherwise joined to a corresponding second yoke 206b. The second yoke 206b includes an opening 206b-o (not shown, see e.g., Figure 4A) therethrough, which is plugged with a second plug 206b-p (Figure 3D). Also shown is a second cross-flux magnet 205b (Figures 3A-3B) embedded within and joined to the second primary magnet 204b. The second crossed flux magnet 205b is magnetized in a direction substantially perpendicular to the direction of the N / S poles 204b-n, 204b-s (here, e.g., in a S to N direction), thus forming a Halbach array. Similar to the rotary VCM, the yoke 206b and primary permanent magnet 204b are configured in an annular shape, with the different N / S poles of the primary permanent magnet 204b positioned circumferentially relative to each other and polarized in a direction substantially perpendicular to the major faces of the primary permanent magnet 204b.

[0019] Method for Assembling a VCM Assembly with Crossed Flux Magnets 4A-4F are each perspective views illustrating stages of an assembly process for a half assembly of the improved VCM assembly of FIG. 3A, according to one embodiment. In particular, FIG. 4A is a perspective view illustrating a first stage of an assembly process for the half assembly of the improved VCM assembly of FIG. 3A. FIG. 4B is a perspective view illustrating a second stage of an assembly process for the half assembly of the improved VCM assembly of FIG. 3A. FIG. 4C is a perspective view illustrating a third stage of an assembly process for the half assembly of the improved VCM assembly of FIG. 3A. FIG. 4D is a perspective view illustrating a fourth stage of an assembly process for the half assembly of the improved VCM assembly of FIG. 3A. FIG. 4E is a bottom perspective view illustrating a fourth stage of an assembly process for the half assembly of the improved VCM assembly of FIG. 3A, and FIG. 4F is a perspective view illustrating a fifth stage of an assembly process for the half assembly of the improved VCM assembly of FIG. 3A, all according to one embodiment.

[0020] Figure 5 is a flow diagram illustrating a method of assembling a VCM assembly with cross-flux magnets according to one embodiment. The method of Figure 5 will be described with reference to the assembly stages of Figures 4A-4F for an open-mounted half-assembly of a VCM assembly with cross-flux magnets, such as the half-assembly of the improved VCM assembly of Figure 3A.

[0021] The first stage in FIG. 4A shows a yoke 206b, such as a stamped plate, having an opening 206b-o therethrough. The second stage in FIG. 4B shows an uncharged primary magnet 204b bonded, glued, attached, or otherwise coupled to the yoke 206b, with grooves or channels 204b-c milled or otherwise formed therein at the interface 207. The third stage in FIG. 4C shows the primary magnet 204b coupled to the yoke 206b, where the magnet 204b is now magnetized, charged, polarized, or otherwise configured with north / south poles 204b-n, 204b-s. Consistent with current typical manufacturing processes, the primary magnet 204b is magnetized after being bonded to the yoke 206b, thus incorporating this stage of the process into existing manufacturing processes.

[0022] The fourth stage in Figure 4D shows primary magnet 204b coupled to yoke 206b, where cross flux magnet 205b is installed and embedded within primary magnet 204b. According to one embodiment, cross flux magnet 205b is pre-charged or pre-magnetized prior to installation within primary magnet 204b. In particular, cross flux magnet 205b is embedded within channel 204b-c (Figures 4B-4C) and coupled to primary magnet 204b through opening 206b-o (Figure 4A) in yoke 206b. According to one embodiment, the cross flux magnet 205b is embedded within a pre-formed channel 204b-c such that the cross flux magnet 205b extends from the proximal side (yoke 206b side) or surface (e.g., in the same plane as the primary magnet 204b on the proximal side, more similar to a conventional Halbach array) toward, but not to, the distal side (air gap side) or surface of the primary magnet 204b, and extends from the front side or surface to the rear side or surface of the primary magnet 204b (see, e.g., FIG. 4E). The portion of the primary magnet 204b between the cross flux magnet 205b and the top surface of the primary magnet 204b provides a single piece primary magnet 204b, thereby limiting part count and simplifying manufacturing. As described elsewhere herein, the second cross-flux magnet 205b is magnetized in a direction substantially perpendicular to the direction of the N / S poles 204b-n, 204b-s (here, e.g., in a S to N direction), thus effectively forming a Halbach array. The cross-flux magnet 205b and the channel 204b-c in which it is embedded are each shown as generally rectangular in shape throughout this section and specification for illustrative purposes, although it should be noted that the shape in which the cross-flux magnet 205b and the corresponding channel 204b-c are formed may vary from implementation to implementation. As a non-limiting example, the cross-flux magnet 205b and the corresponding channel 204b-c may be formed in a more trapezoidal shape, whereby the sidewalls of each are tapered / chamfered (e.g., wider on the proximal side and narrower on the distal side) to facilitate installation.

[0023] FIG 4E shows a bottom perspective view of the fourth stage of FIG 4D, again showing primary magnet 204b coupled to yoke 206b and cross-flux magnet 205b mounted therein. FIG 4E further shows opening 206b-o in yoke 206b, through which cross-flux magnet 205b is mounted into and between north / south poles 204b-n, 204b-s of primary magnet 204b. Finally, the fifth stage of FIG 4F shows the configuration of FIG 4D-E with plug 206b-p further mounted into opening 206b-o (FIG 4E), the use of plug 206b-p providing the desired, largely uninterrupted magnetic flux path of yoke 206b.

[0024] 5, openings are created in the yoke at block 502. For example, openings 206b-o are formed in source yoke 206b (see, for example, FIG. 4A) using machining or other common manufacturing techniques.

[0025] At block 504, a primary magnet is attached to an inner surface of a yoke. For example, primary magnet 204b is attached to an inner surface of yoke 206b (see, for example, FIG. 4B). According to one embodiment, prior to attaching primary magnet 204b, channels 204b-c (FIGS. 4B-4C) having a shape matching cross-flux magnet 205b are formed in primary magnet 204b. However, channels 204b-c may alternatively be formed in situ after primary magnet 204b is bonded to yoke 206b.

[0026] At block 506, the cross-flux magnets are placed into the channels of the primary magnets through openings in the yoke. For example, the cross-flux magnets 205b (FIGS. 4D-4F) are placed into the channels 204b-c (FIGS. 4B-4C) of the primary magnets 204b through openings 206b-o in the yoke 206b, i.e., "in-situ." According to one embodiment, after the primary magnets are attached (block 504) and before the cross-flux magnets are placed (block 506), the primary magnets 204b are charged to set opposite magnetization directions, i.e., north / south poles 204b-n, 204b-s, on each side or portion of the primary magnet, as depicted at the boundary 207 (FIG. 4B) between the poles 204b-n, 204b-s. According to one embodiment, prior to installation onto the primary magnet 204b, the cross-flux magnet 205b is charged to set its magnetization direction substantially perpendicular to the magnetization direction of the primary magnet 204b.

[0027] At block 508, a plug is placed into an opening in the yoke. For example, stainless steel plugs 206b-p (FIG. 4F) are placed into openings 206b-o of stainless steel yoke 206b. Note that different iron alloy materials other than stainless steel may be used, but it is preferred to use the same material for plugs 206b-p and yoke 206b.

[0028] Classical Halbach arrays require a minimum of three magnetic components, each pre-magnetized, to be assembled and bonded together while exerting forces on each other. This presents a challenging process considering the size and strength of the magnets used in the HDD VCM. Overall, the approach described herein improves over conventional HDD VCMs primarily in the strength of the VCM magnetic field relative to the total amount of magnetic material required. Furthermore, fewer total parts are used and the manufacturing process is easily integrated into existing VCM manufacturing processes, which may provide a better cost advantage over existing implementations of Halbach arrays in HDD VCMs.

[0029] Physical Description of Exemplary Operational Contexts Embodiments may be used in the context of a digital data storage device (DSD), such as a hard disk drive (HDD). Thus, according to one embodiment, a plan view showing a conventional HDD 100 is shown in FIG. 1 to help explain how a conventional HDD typically operates.

[0030] FIG. 1 shows a functional arrangement of components of a HDD 100, including a slider 110b that includes a magnetic read-write head 110a. Collectively, the slider 110b and the head 110a may be referred to as a head slider. The HDD 100 includes at least one head gimbal assembly (HGA) 110 that includes a head slider, a lead suspension 110c that is typically attached to the head slider via a flexure, and a load beam 110d that is attached to the lead suspension 110c. The HDD 100 also includes at least one recording medium 120 that is rotatably mounted on a spindle 124, and a drive motor (not shown) that is attached to the spindle 124 to rotate the medium 120. The read-write head 110a, which may also be referred to as a transducer, includes a write element and a read element for writing and reading information stored on the medium 120 of the HDD 100, respectively. The medium 120 or multiple disk media may be secured to a spindle 124 with a disk clamp 128 .

[0031] The HDD 100 further includes an arm 132 attached to the HGA 110, a carriage 134, a voice coil motor (VCM) including an armature 136 including a voice coil 140 attached to the carriage 134, and a stator 144 including a voice coil magnet (not shown). The VCM armature 136 is attached to the carriage 134 and is configured to move the arm 132 and HGA 110 to access portions of the media 120, all collectively mounted on a pivot shaft 148 with an intervening pivot bearing assembly 152. In HDDs with multiple disks, the carriage 134 may be referred to as an "E-block" or comb because the carriage is arranged to carry an interlocking arrangement of arms that give the carriage the appearance of a comb.

[0032] An assembly comprising a head gimbal assembly (e.g., HGA 110), including a flexure to which a head slider is coupled, an actuator arm (e.g., arm 132) and / or a load beam to which the flexure is coupled, and an actuator (e.g., VCM) to which the actuator arm is coupled, may be collectively referred to as a head-stack assembly (HSA). However, an HSA may include more or less components than those listed. For example, an HSA may refer to an assembly that further includes electrical interconnection components. In general, an HSA is an assembly configured to move a head slider to access portions of the medium 120 for read and write operations.

[0033] With further reference to FIG. 1 , electrical signals including write signals to and read signals from head 110a (e.g., current to the voice coil 140 of the VCM) are transmitted by a Flexible Cable Assembly (FCA) 156 (or “flex cable,” or “Flexible Printed Circuit” (FPC)). The interconnect between the flex cable 156 and head 110a may include an Arm-Electronics (AE) module 160, which may have on-board preamplifiers for the read signals, as well as other read channel and write channel electronic components. The AE module 160 may be mounted to the carriage 134 as shown. The flex cable 156 may be coupled to an electrical connector block 164 that, in some configurations, provides electrical communication through an electrical feed-through provided by the HDD housing 168. The HDD housing 168 (or "enclosure base" or "baseplate" or "motor base assembly" or simply "base"), together with the HDD cover, provides a semi-sealed (or, in some configurations, hermetically sealed) protective enclosure for the information storage components of the HDD 100.

[0034] A disk controller including a Digital-Signal Processor (DSP) and other electronic components including servo electronics provide electrical signals to the drive motor, the voice coil 140 of the VCM, and the head 110a of the HGA 110. The electrical signals provided to the drive motor enable the drive motor to rotate providing a torque to the spindle 124, which is then transferred to the medium 120 affixed to the spindle 124. As a result, the medium 120 rotates in a direction 172. The rotating medium 120 creates a cushion of air that acts as an air-bearing on which the air-bearing surface (ABS) of the slider 110b rides so that the slider 110b flies above the surface of the medium 120 without contacting the thin magnetic recording layer on which the information is recorded. Similarly, as a non-limiting example, in HDDs that utilize a lighter-than-air gas such as helium, the rotating medium 120 creates a cushion of gas that acts as a gas or fluid bearing upon which the slider 110b rides.

[0035] An electrical signal provided to the voice coil 140 of the VCM enables the head 110a of the HGA 110 to access the track 176 on which information is to be recorded. Thus, the armature 136 of the VCM swings through an arc 180 to enable the head 110a of the HGA 110 to access various tracks on the medium 120. Information is stored on the medium 120 in a plurality of radially nested tracks arranged in sectors on the medium 120, such as sector 184. Correspondingly, each track is made up of a plurality of sectorized track portions (or "track sectors"), such as sectorized track portion 188. Each sectorized track portion 188 may include the recorded information and a header that includes error correction code information and a servo burst signal pattern, such as an ABCD servo burst signal pattern, which is information identifying the track 176. When accessing track 176, a read element of head 110a of HGA 110 reads the servo burst signal pattern, which provides a Position-Error-Signal (PES) to the servo electronics, which enables head 110a to follow track 176 by controlling an electrical signal provided to the voice coil 140 of the VCM. Having found track 176 and identified a particular sectorized track portion 188, head 110a reads information from track 176 or writes information to track 176 in response to instructions received by a disk controller from an external agent, e.g., a microprocessor of a computer system.

[0036] The electronic architecture of an HDD includes numerous electronic components, such as a Hard Disk Controller ("HDC"), an interface controller, an arm electronics module, a data channel, a motor driver, a servo processor, a buffer memory, and the like, each performing its own respective function for the operation of the HDD. Two or more of such components may be combined on a single integrated circuit board, referred to as a "System On a Chip" ("SOC"). Some, if not all, of such electronic components are typically located on a printed circuit board that is coupled to the bottom side of the HDD, such as the HDD housing 168.

[0037] References herein to hard disk drives, such as HDD 100 shown and described with reference to FIG. 1, may encompass information storage devices sometimes referred to as "hybrid drives." A hybrid drive generally refers to a storage device that has the functionality of both a traditional HDD (see, e.g., HDD 100) combined with a solid-state storage device (SSD) that uses non-volatile memory such as electrically erasable and programmable flash or other solid-state (e.g., integrated circuit) memory. Because the operation, management, and control of different types of storage media are typically different, the solid-state portion of a hybrid drive may include its own corresponding controller functionality, or the controller functionality may be integrated into a single controller along with the HDD functionality. A hybrid drive may be designed and configured to operate and utilize the solid-state portion in several ways, such as by using the solid-state memory as a cache memory, as a non-limiting example, to store frequently accessed data, to store I / O intensive data, and the like. Additionally, a hybrid drive may be designed and constructed essentially as two storage devices, a traditional HDD and an SSD, in a single enclosure, with either one or multiple interfaces for host connection.

[0038] Augmentations and Alternatives In the foregoing description, the embodiments of the invention have been described with reference to numerous specific details that may vary from implementation to implementation. Accordingly, various modifications and changes may be made without departing from the broader spirit and scope of the embodiments. Thus, the sole and exclusive reference of what is the invention, and what the applicants intend to be the invention, is the set of claims originating from this application, in the particular form from which such claims originate, including any subsequent amendments. The definitions expressly set forth herein for the terms contained in such claims shall govern the meaning of the terms as used in the claims. Hence, any limitations, elements, characteristics, features, advantages or attributes not expressly set forth in the claims should in no way limit the scope of such claims. Hereby, the specification and drawings should be regarded in an illustrative and not restrictive sense.

[0039] It should be noted that in this description, certain process steps may be described in a particular order, and alphabetic and alphanumeric labels may be used to identify certain steps. Unless otherwise specified herein, embodiments are not necessarily limited to any particular order of performing such steps. In particular, the labels are used merely for convenient identification of the steps, and are not intended to specify or require a particular order of performing such steps.

Claims

1. 1. A method of assembling a voice coil motor (VCM), comprising the steps of: creating an opening in the yoke; attaching a primary magnet to an inner surface of the yoke; placing a cross flux magnet through the opening in the yoke and into the channel of the primary magnet; and placing a plug into the opening in the yoke.

2. 10. The method of claim 1, further comprising charging the primary magnets after mounting and before installing the cross-flux magnets to set opposite magnetization directions on each side of a boundary.

3. The method of claim 2 , wherein placing the cross flux magnets comprises placing the cross flux magnets substantially at the boundary.

4. 10. The method of claim 1, further comprising charging the cross flux magnets prior to installation within the primary magnet to set their magnetization direction substantially perpendicular to the magnetization direction of the primary magnet.

5. The method of claim 1 , further comprising forming the channel in the primary magnet having a shape that matches the cross flux magnet before attaching the primary magnet.

6. 6. The method of claim 5, wherein forming the channel comprises forming a channel that extends from a proximal side of the primary magnet toward a distal side of the primary magnet, but not to the distal side of the primary magnet.

7. The method of claim 1 , wherein installing the plug comprises installing a plug constructed from the same material as the yoke.

8. creating an opening in a second yoke; attaching a second primary magnet to an inner surface of the second yoke; charging the second primary magnet to establish opposite magnetization directions on each side of a magnetic boundary; placing a pre-charged crossed flux magnet through the opening in the second yoke and into the channel of the second primary magnet; The method of claim 1 , further comprising: placing a plug into the opening in the second yoke.

9. 9. The method of claim 8, further comprising coupling the yoke, the primary magnet, and the crossed flux magnet assembly to the second yoke, the second primary magnet, and the second crossed flux magnet assembly.

10. 10. A voice coil motor manufactured according to the method of claim 9.

11. a first yoke having an opening, the opening being plugged with a first plug; a first primary magnet joined to the first yoke, having a proximal side adjacent to the first yoke and having an opposing distal side, the first primary magnet being configured with opposite magnetic poles having opposite magnetization directions on each side of a first boundary; a first cross flux magnet embedded within the first primary magnet through the opening in the first yoke and joined to the first primary magnet and having a proximal side adjacent to the first yoke, the cross flux magnet configured to have a magnetization direction substantially perpendicular to the magnetization direction of the first primary magnet; a second yoke having an opening, the opening being plugged by a second plug; a second primary magnet joined to the second yoke and having a proximal side adjacent to the second yoke and having an opposing distal side, the second primary magnet being configured with opposite magnetic poles having opposite magnetization directions on each side of a second boundary; a second cross flux magnet embedded within the second primary magnet through the opening in the second yoke and joined to the second primary magnet and having a proximal side adjacent to the second yoke, the second cross flux magnet configured to have a magnetization direction substantially perpendicular to the magnetization direction of the second primary magnet.

12. 12. The VCM of claim 11, wherein the first crossed flux magnet is embedded substantially at the first boundary and the second crossed flux magnet is embedded substantially at the second boundary.

13. a first channel extending from the proximal side of the first primary magnet toward but not all the way to the distal side of the first primary magnet, the first cross flux magnet being embedded therein; 12. The VCM of claim 11, further comprising: a second channel extending from the proximal side of the second primary magnet toward but not to the distal side of the second primary magnet, in which the second cross flux magnet is embedded.

14. 14. The VCM of claim 13, wherein the first channel extends from a front side to a rear side of the first primary magnet and the second channel extends from a front side to a rear side of the second primary magnet.

15. The VCM of claim 11 , wherein the first yoke and the first plug are constructed from the same material.

16. A plurality of disk media rotatably mounted on a spindle motor; a plurality of head sliders, each housing a read-write transducer configured to read from and write to a respective one of the plurality of disk media; a voice coil motor (VCM) assembly configured to move the plurality of head sliders to access portions of the plurality of disk media, a first yoke having an opening, the opening being filled with a first plug made of the same material as the first yoke; a first primary magnet joined to the first yoke, having a proximal side adjacent to the first yoke and having an opposing distal side, the first primary magnet being configured with opposite magnetic poles having opposite magnetization directions on each side of a first boundary; a first cross flux magnet embedded within the first primary magnet through the opening in the first yoke and joined to the first primary magnet and having a proximal side adjacent to the first yoke, the first cross flux magnet configured to have a magnetization direction substantially perpendicular to the magnetization direction of the first primary magnet; a second yoke having an opening, the opening being filled with a second plug made of the same material as the second yoke; a second primary magnet joined to the second yoke and having a proximal side adjacent to the second yoke and having an opposing distal side, the second primary magnet being configured with opposite magnetic poles having opposite magnetization directions on each side of a second boundary; and a second cross flux magnet embedded within the second primary magnet through the opening in the second yoke and joined to the second primary magnet and having a proximal side adjacent to the second yoke, the second cross flux magnet configured to have a magnetization direction substantially perpendicular to the magnetization direction of the second primary magnet.

17. 17. The HDD of claim 16, wherein the magnetization direction of the first crossed flux magnet is opposite to the magnetization direction of the second crossed flux magnet.

18. 17. The HDD of claim 16, wherein the first crossed flux magnet is embedded substantially at the first boundary and the second crossed flux magnet is embedded substantially at the second boundary.

19. a first channel extending from the proximal side of the first primary magnet toward but not all the way to the distal side of the first primary magnet, the first cross flux magnet being embedded therein; 17. The HDD of claim 16, further comprising: a second channel extending from the proximal side of the second primary magnet toward but not to the distal side of the second primary magnet, in which the second cross flux magnet is embedded.

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