In-situ installation of cross-flux magnets in a voice coil motor actuator

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, filed on July 20, 2023, which claims the priority of U.S. Provisional Application No. 63 / 435,405, filed on December 27, 2022, the entire content of which is incorporated herein by reference for all purposes.

[0002] Embodiments of the present invention generally relate to voice coil motors, and more particularly, to hard disk drive rotary voice coil actuators having cross - flux magnets installed through a primary magnet housing.

Background Art

[0003] A hard disk drive (HDD) is a non-volatile memory device that is housed within a protective enclosure and stores digitally encoded data on one or more circular disks having a magnetic surface. When the HDD is operating, each magnetic recording disk is rapidly rotated by a spindle system. Data is read from and written to the magnetic recording disk using a read-write head (or “transducer”) housed in a slider positioned over a specific location on the disk 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 functions by generating a magnetic field using an electric current flowing through the coil of the write head. Electric pulses are sent to the write head with different patterns of positive and negative current. The current in the coil of the write head generates a local magnetic field across the gap between the head and the magnetic recording disk, thereby magnetizing a small area on this recording medium.

[0004] Typically, a voice coil motor (VCM) is a type of actuator employed in an HDD to move the read-write head to access a corresponding portion of the magnetic recording disk for read and write operations. VCMs rely on permanent magnets for their persistent magnetic fields. Such magnetic fields are typically strongest at the magnet surface and decrease as they move away from it, and thus the magnetic flux density also decreases as it moves away from the magnet. Additionally, the cost of the permanent magnet typically scales with the corresponding grade of the magnet and the material from which the magnet is fabricated, with higher grades indicating stronger magnets. Increasing areal density (a measure of the amount of information bits that can be stored in a given area of the disk surface) is one of the ongoing goals of the technological evolution of hard disk drives. Given the trend towards higher areal density in HDDs, performance improvements to the VCM may be desirable.

[0005] The approaches described in this section are approaches that are pursuable, but not necessarily approaches that have been previously devised or pursued. Therefore, unless otherwise indicated, none of the approaches described in this section should be regarded as being eligible as prior art solely by virtue of their inclusion in this section.

Brief Description of the Drawings

[0006] The embodiments are shown by way of example and not limitation in the figures of the accompanying drawings, and like reference numerals refer to like elements.

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[0007] Generally, an approach to an improved voice coil motor (VCM) assembly having a cross-flux magnet, such as used in a hard disk drive (HDD), 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. However, it will be apparent 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 Terms References herein to "an embodiment", "one embodiment", etc. are intended to mean that a particular feature, structure, or characteristic described is included in at least one embodiment of the invention. However, such phrases are not necessarily all referring to the same embodiment.

[0009] The term "substantially" is understood to describe features such as mostly structured or nearly structured, mostly composed or nearly composed, mostly dimensioned or nearly dimensioned, etc., but manufacturing tolerances and the like can in fact result in situations where the structure, composition, dimensions, etc. are not always or necessarily precisely described. For example, if a structure is described as "substantially vertical", the sidewalls are vertical for all practical purposes, but the term is assigned its obvious meaning in that they may not be exactly 90 degrees throughout.

[0010] Terms such as "optimal", "optimize", "minimal", "minimize", "maximal", "maximize", etc. may not have a specific value associated with them, but when such terms are used in this specification, one of ordinary skill in the art is intended to understand that such terms include affecting values, parameters, metrics, etc. in a beneficial direction consistent with the overall disclosure. For example, describing something as having a "minimal" value does not require that the value be actually equal to the theoretical minimum value (e.g., zero), but should be understood in a practical sense in that the corresponding goal is to move the value in a beneficial direction towards the theoretical minimum value.

[0011] Context It is desirable to recall the finding that performance improvement for a VCM may be desired. The torque generated by a VCM is proportional to the magnetic flux density generated by the corresponding permanent magnet in that the motor efficiency increases as the magnetic flux density increases. Thus, the higher the magnetic field gradient generated by the permanent magnet, the more likely the VCM is to operate more efficiently. However, since HDDs have very limited space, the approaches available for building a better VCM are similarly limited.

[0012] Open-set Halbach voice coil motor FIG. 2 is a perspective view showing an improved voice coil motor (VCM) assembly having a cross-flux magnet according to one embodiment. The VCM assembly 200 (“VCM 200”) includes a first magnet assembly 202a and a second magnet assembly 202b coupled to each other. For example, the first primary magnet assembly 202a and the second primary magnet assembly 202b may be joined to each other or manufactured as an integral assembly.

[0013] The first magnet assembly 202a includes 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 the first boundary, and is joined to a corresponding first yoke 206a. The first yoke 206a includes an opening 206a-o therethrough, and the opening is plugged with a first plug 206a-p. According to one embodiment, the first yoke 206a and the first plug 206a-p are made of the same material, such as stainless steel, for example. In particular, the first magnet assembly 202a further includes a first cross-flux magnet 205a embedded and joined 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, for example, FIGS. 4B-4C) in the first primary magnet 204a and extends from the proximal side (yoke 206a side) or surface of the first primary magnet 204a towards the distal side (air gap side) or surface of the first primary magnet 204a, but does not extend to the distal side or surface of the first primary magnet 204a, and extends from the front side or surface of the first primary magnet 204a to the rear side or surface of the first primary magnet 204a. The first cross-flux magnet 205a is magnetized in a direction substantially perpendicular (i.e., vertical) to the direction of the N / S poles 204a-n, 204a-s (here, for example, the direction from N to S), and thus forms what is referred to as a Halbach array. Generally, a Halbach array is a special arrangement of permanent magnets that increases the magnetic field (e.g., enhances the magnetic flux) on one side of the array by having a spatially rotating magnetization pattern, while canceling the magnetic field to nearly zero (e.g., cancels the magnetic flux) on the other side.

[0014] Here, this Halbach array effect is enabled by the embedded and properly 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 the in-situ assembly technique enabled by the use of the opening 206a-o through the first yoke 206a into which the first cross-flux magnet 205a is inserted and sealed with the first plug 206a-p results in an improvement of the classical Halbach array that requires fewer total components (compared to composite magnets or other forms of Halbach array assemblies manufactured outside the first magnet assembly 202a) and significantly reduces manufacturing complexity at the expense of a small amount of optimality.

[0015] Similarly, the second magnet assembly 202b includes 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 the 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, and the opening is plugged with a second plug 206b-p (not shown, see, e.g., FIGS. 3D and 4F). According to one embodiment, the second yoke 206b and the second plug 206b-p are made of the same material, such as stainless steel, for example. Here too, the second magnet assembly 202b further includes 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, e.g., channel 204b-c in FIGS. 4B-4C) in the second primary magnet 204b and extends from the proximal side (yoke 206b side) or surface of the second primary magnet 204b towards the distal side (air gap side) or surface of the second primary magnet 204b, but does not extend to the distal side (air gap side) or surface of the second primary magnet 204b and extends from the front side or surface of the second primary magnet 204b to the 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 the direction from S to N), and thus forms a Halbach array. Here too, this Halbach array effect is made possible by the second cross-flux magnet 205b being embedded in and properly magnetized 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), and the Halbach array results in fewer total components being required and a reduction in manufacturing complexity.

[0016] The first primary magnet 204a and the second primary magnet 204b are shown throughout this section and the entire specification with portions magnetized in a particular direction (i.e., N / S poles 204a-n, 204a-s, and N / S poles 204b-n, 204b-s) for purposes of illustration, but it should be noted that the direction in which each of the poles 204a-n, 204a-s, 204b-n, 204b-s is magnetized can vary from implementation to implementation. For example, the poles shown as 204a-n and 204b-n may actually be magnetized in the S direction, while the poles shown as 204a-s and 204b-s may actually be magnetized in the N direction. Similarly, the first cross-flux magnet 205a and the second cross-flux magnet 205b are shown magnetized in a particular direction for purposes of illustration, but 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 a direction opposite to that shown herein, so long as each is magnetized in a direction substantially perpendicular to the direction of the N / S poles 204a-n, 204a-s, 204b-n, 204b-s. Further, a complete VCM assembly may be implemented having 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 an embedded cross-flux magnet.

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

[0018] Collectively, FIGS. 3A-3D show a second magnet assembly 202b that includes 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 that is adhered to or otherwise joined to a corresponding second yoke 206b. The second yoke 206b includes an opening 206b-o (not shown, see, e.g., FIG. 4A for example) therethrough, and the opening is plugged with a second plug 206b-p (FIG. 3D). Also shown is a second cross-flux magnet 205b (FIGS. 3A-3B) that is embedded within and joined to the second primary magnet 204b. The second cross-flux magnet 205b is magnetized in a direction that is substantially perpendicular to the direction of the N / S poles 204b-n, 204b-s (here, for example, in the direction from S to N), and thus forms a Halbach array. Similar to the rotating VCM, the yoke 206b and the primary permanent magnet 204b are configured in an annular shape, and the different N / S poles of the primary permanent magnet 204b are circumferentially positioned relative to each other and polarized in a direction that is substantially perpendicular to the main surface of the primary permanent magnet 204b.

[0019] Method of assembling a VCM assembly having a cross-flux magnet Figures 4A - 4F are perspective views showing the 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 showing the first stage of the assembly process for the half - assembly of the improved VCM assembly of FIG. 3A. FIG. 4B is a perspective view showing the second stage of the assembly process for the half - assembly of the improved VCM assembly of FIG. 3A. FIG. 4C is a perspective view showing the third stage of the assembly process for the half - assembly of the improved VCM assembly of FIG. 3A. FIG. 4D is a perspective view showing the fourth stage of the assembly process for the half - assembly of the improved VCM assembly of FIG. 3A. FIG. 4E is a bottom perspective view showing the fourth stage of the assembly process for the half - assembly of the improved VCM assembly of FIG. 3A, and FIG. 4F is a perspective view showing the fifth stage of the assembly process for the half - assembly of the improved VCM assembly of FIG. 3A, and all of these are according to one embodiment.

[0020] FIG. 5 is a flow diagram showing a method of assembling a VCM assembly having a cross - flux magnet, according to one embodiment. The method of FIG. 5 is described with reference to the assembly stages of FIGS. 4A - 4F for an open - placed half - assembly of a VCM assembly having a cross - flux magnet, such as the half - assembly of the improved VCM assembly of FIG. 3A.

[0021] The first stage of FIG. 4A shows a yoke 206b, such as a stamped plate, which has an opening 206b-o therethrough. The second stage of FIG. 4B shows an uncharged primary magnet 204b joined, adhered, attached, or otherwise coupled to the yoke 206b, the primary magnet 204b having a groove or channel 204b-c ground or otherwise formed therein at the boundary 207. The third stage of FIG. 4C shows the primary magnet 204b coupled to the yoke 206b, the magnet 204b now being magnetized, charged, polarized, or otherwise configured with N / S poles 204b-n, 204b-s. Consistent with current typical manufacturing processes, the primary magnet 204b is magnetized after being joined to the yoke 206b, thus incorporating this stage of the process into existing manufacturing processes.

[0022] The fourth stage of FIG. 4D shows the primary magnet 204b coupled to the yoke 206b, where the cross-flux magnet 205b is disposed and embedded within the primary magnet 204b. According to one embodiment, the cross-flux magnet 205b is pre-charged or pre-magnetized prior to being installed within the primary magnet 204b. In particular, the cross-flux magnet 205b is embedded within the channel 204b-c (FIGS. 4B-4C) and is joined to the primary magnet 204b through the opening 206b-o (FIG. 4A) within the yoke 206b. According to one embodiment, 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, similar to a conventional Halbach array) of the primary magnet 204b towards the distal side (air gap side) or surface of the primary magnet 204b, but does not extend 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 (e.g., see FIG. 4E), and is embedded within the pre-formed channel 204b-c. The portion of the primary magnet 204b between the cross-flux magnet 205b and the upper surface of the primary magnet 204b provides a single-piece primary magnet 204b, thereby limiting the number of components and simplifying manufacturing. As described elsewhere in this specification, 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 the direction from S to N), and thus effectively forms a Halbach array. The cross-flux magnet 205b and the channel 204b-c in which the cross-flux magnet 205b is embedded are each shown generally rectangular in shape for illustrative purposes throughout this section and the entire specification, but it should be noted that the shape in which the cross-flux magnet 205b and the corresponding channel 204b-c are formed can vary for each mounting configuration. 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 each sidewall is 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, and also shows a primary magnet 204b coupled to the yoke 206b and an intersecting flux magnet 205b installed therein. FIG. 4E further shows an opening 206b-o in the yoke 206b through which the intersecting flux magnet 205b is installed into and between the N / S poles 204b-n, 204b-s of the primary magnet 204b. Finally, the fifth stage of FIG. 4F shows the configuration of FIGS. 4D-4E with the plug 206b-p further installed into the opening 206b-o (FIG. 4E), and the use of the plug 206b-p provides a mostly uninterrupted magnetic flux path in the yoke 206b as desired.

[0024] Referring now to FIG. 5, at block 502, an opening is created in the yoke. For example, using machining or other common manufacturing techniques, an opening 206b-o is formed in the source yoke 206b (see, e.g., FIG. 4A).

[0025] At block 504, the primary magnet is attached to the inner surface of the yoke. For example, the primary magnet 204b is attached to the inner surface of the yoke 206b (see, e.g., FIG. 4B). According to one embodiment, prior to attaching the primary magnet 204b, a channel 204b-c (FIGS. 4B-4C) having a shape that matches the intersecting flux magnet 205b is formed in the primary magnet 204b. However, the channel 204b-c may alternatively be formed in place after the primary magnet 204b is joined to the yoke 206b.

[0026] In block 506, the cross-flux magnet is installed into the channel of the primary magnet through the opening in the yoke. For example, through the opening 206b-o in the yoke 206b, that is, "in-situ", the cross-flux magnet 205b (Figs. 4D-4F) is installed into the channel 204b-c (Figs. 4B-4C) of the primary magnet 204b. According to one embodiment, after the primary magnet is attached (block 504) and before the cross-flux magnet is installed (block 506), the primary magnet 204b is charged to set the magnetization directions opposite to each other on each side or part of the primary magnet, that is, the N / S poles 204b-n, 204b-s, as depicted at the boundary 207 (Fig. 4B) between the poles 204b-n, 204b-s. According to one embodiment, the cross-flux magnet 205b is charged to set a magnetization direction substantially perpendicular to the magnetization direction of the primary magnet 204b before installing it into the primary magnet 204b.

[0027] In block 508, the plug is installed into the opening in the yoke. For example, the stainless-steel plug 206b-p (Fig. 4F) is installed into the opening 206b-o of the stainless-steel yoke 206b. Although different ferroalloy materials other than stainless steel may be used, it is preferable to use the same material for the plug 206b-p and the yoke 206b.

[0028] A classical Halbach array requires at least three pre-magnetized magnetic components to be assembled and joined together while exerting forces on each other. This presents a difficult process considering the size and strength of the magnets used in HDD VCMs. Generally, the approach described herein is improved over conventional HDD VCMs mainly in terms of the strength of the VCM magnetic field relative to the total amount of magnetic material required. Furthermore, the total number of parts used is less, and the manufacturing process can be easily incorporated into existing VCM manufacturing processes, and such manufacturing ease can result in better cost advantages over existing implementations of the Halbach array in HDD VCMs.

[0029] Physical Explanation of an Exemplary Operating Context 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 HDD100 is shown in FIG. 1 to assist in explaining how a conventional HDD typically operates.

[0030] FIG. 1 shows a functional arrangement of components of an HDD100, 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 HDD100 includes at least one Head Gimbal Assembly (HGA) 110 that includes the head slider, a read suspension 110c typically attached to the head slider via a flexure, and a load beam 110d attached to the read suspension 110c. The HDD100 also includes at least one recording medium 120 rotatably attached to a spindle 124, and a drive motor (not shown) attached to the spindle 124 for rotating 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, respectively, information stored on the medium 120 of the HDD100. The medium 120 or multiple disk media may be fixed to the spindle 124 by a disk clamp 128.

[0031] The HDD 100 further includes a voice coil motor (VCM) including an arm 132 attached to the HGA 110, a carriage 134, and 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 armature 136 of the VCM is attached to the carriage 134 and is configured to move the arm 132 and the HGA 110 to access a portion of the medium 120, and all are collectively mounted on a pivot shaft 148 by an intervening pivot bearing assembly 152. In the case of an HDD having a plurality of disks, the carriage 134 may be referred to as an "E-block" or a comb because the carriage is arranged to carry an interlocking arm arrangement that gives the carriage a comb-like appearance.

[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, the HSA may include more or fewer components than those described. For example, the HSA may refer to an assembly that further includes electrical interconnection components. Generally, the HSA is an assembly configured to move a head slider to access a portion of the medium 120 for read and write operations.

[0033] Referring further to FIG. 1, electrical signals (e.g., current to voice coil 140 of the VCM) including a write signal to head 110a and a read signal from head 110a are transmitted by a Flexible Cable Assembly (FCA) 156 (or "flex cable", or "Flexible Printed Circuit" (FPC)). The interconnection between flex cable 156 and head 110a may include an Arm-Electronics (AE) module 160 that may have an on-board preamplifier for the read signal, as well as other read and write channel electronic components. The AE module 160 may be attached to the carriage 134 as shown. The flex cable 156 may, in some configurations, be coupled to an electrical connector block 164 that 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") provides, together with the HDD cover, a semi-enclosed (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 a drive motor, the voice coil 140 of the VCM, and the head 110a of the HGA110. The electrical signal provided to the drive motor enables the drive motor to rotate while providing torque to the spindle 124, and then the torque is transmitted to the medium 120 attached to the spindle 124. As a result, the medium 120 rotates in the direction 172. The rotating medium 120 acts as an air bearing on which the air - bearing surface (ABS) of the slider 110b rides, generating an air cushion such that the slider 110b floats above the surface of the medium 120 without contacting the thin magnetic recording layer on which information is recorded. Similarly, as a non - limiting example, in an HDD where a gas lighter than air, such as helium, is utilized, the rotating medium 120 acts as a gas or fluid bearing on which the slider 110b rides, generating a gas cushion.

[0035] The 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 recorded. Thus, the armature 136 of the VCM swing through the arc 180 enables the head 110a of the HGA 110 to access various tracks on the medium 120. Information is stored on the medium 120 within a plurality of radially nested tracks disposed on sectors on the medium 120, such as sector 184. Correspondingly, each track is composed of a plurality of sectored track portions (or "track sectors"), such as the sectored track portion 188. Each sectored track portion 188 may include a header containing the recorded information, error correction code information, and a servo burst signal pattern, such as the ABCD servo burst signal pattern, which is information for identifying the track 176. When accessing the track 176, the read element of the head 110a of the HGA 110 reads the servo burst signal pattern, which provides a position-error-signal (PES) to the servo electronics, and the servo electronics enables the head 110a to follow the track 176 by controlling the electrical signal provided to the voice coil 140 of the VCM. After finding the track 176 and identifying a particular sectored track portion 188, the head 110a reads information from the track 176 or writes information to the track 176 in response to an instruction received by the disk controller from an external agent, such as a microprocessor of a computer system.

[0036] The electronic architecture of an HDD includes a number of electronic components for performing their respective functions for the operation of the HDD, such as a Hard Disk Controller (HDC), an interface controller, an arm electronic module, a data channel, a motor driver, a servo processor, a 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). Some, but not all, of such electronic components are typically disposed on a printed circuit board coupled to the bottom side of the HDD, such as the HDD housing 168.

[0037] References in this specification to hard disk drives, such as the HDD 100 shown and described with reference to FIG. 1, may include information storage devices sometimes referred to as "hybrid drives". A hybrid drive generally refers to a storage device having the functions of both a conventional HDD (e.g., refer to HDD 100) combined with a solid-state storage device (SSD) that uses non-volatile memory such as flash or other solid-state (e.g., integrated circuit) memory that is electrically erasable and programmable. Since the operation, management, and control of different types of storage media are usually different, the solid-state portion of a hybrid drive may include its corresponding controller function, and the controller function may be integrated into a single controller together with the HDD function. A hybrid drive may be designed and configured to operate and utilize the solid-state portion in several ways, such as using the solid-state memory as a cache memory for storing frequently accessed data, storing I / O-intensive data, etc. Further, a hybrid drive may be essentially designed and configured as two storage devices in a single enclosure, i.e., a conventional HDD and an SSD, with any one of one or more interfaces for host connection.

[0038] Extensions and alternatives In the foregoing description, embodiments of the present 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 indicator of what is the present invention and what the applicants intend to be the present invention is the set of claims that emanate from this application, and which take on a particular form, including any subsequent amendments. The definitions expressly set forth herein for terms that are included in such claims shall govern the meaning of the terms as used in the claims. Therefore, limitations, elements, features, characteristics, advantages or attributes that are not expressly recited in the claims should in no way limit the scope of such claims. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense.

[0039] Note that in this description, certain process steps may be described in a particular order and may be identified using alphabetical and alphanumeric labels. Unless otherwise specified herein, embodiments are not necessarily limited to any particular order in which such steps are performed. In particular, the labels are used merely for convenient identification of the steps and are not intended to specify or require a particular order in which such steps are performed. The following items are elements described in the claims at the time of international filing. (Item 1) A method of assembling a voice coil motor (VCM), comprising: creating an opening in a yoke; attaching a primary magnet to an inner surface of the yoke; installing an intersecting flux magnet into a channel of the primary magnet through the opening in the yoke; and installing a plug into the opening in the yoke. (Item 2) The method according to item 1, further comprising charging the primary magnet so as to set opposite magnetization directions on respective sides of a boundary after attaching the primary magnet and before installing the intersecting flux magnet. (Item 3) The method according to item 2, wherein installing the intersecting flux magnet includes installing the intersecting flux magnet substantially at the boundary. (Item 4) The method according to item 1, further comprising charging the intersecting flux magnet so as to set a magnetization direction substantially perpendicular to the magnetization direction of the primary magnet before installing the intersecting flux magnet into the primary magnet. (Item 5) The method according to item 1, further comprising forming a channel having a shape matching the intersecting flux magnet in the primary magnet before attaching the primary magnet. (Item 6) The method according to item 5, wherein forming the channel includes forming a channel that extends from a proximal side of the primary magnet toward a distal side of the primary magnet but does not extend to the distal side of the primary magnet. (Item 7) The method according to item 1, wherein installing the plug includes installing a plug made of the same material as the yoke. (Item 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 set opposite magnetization directions on respective sides of a magnetic boundary; installing a pre-charged intersecting flux magnet into a channel of the second primary magnet through the opening in the second yoke; and installing a plug into the opening in the second yoke. (Item 9) The method of item 8, further comprising coupling the assembly of the yoke, the primary magnet, and the cross-flux magnet to the assembly of the second yoke, the second primary magnet, and the second cross-flux magnet. (Item 10) A voice coil motor manufactured according to the method of item 9. (Item 11) A first yoke having an opening, wherein the opening is plugged by a first plug, and the first yoke, A first primary magnet joined to the first yoke, having a proximal side adjacent to the first yoke and an opposing distal side, wherein the first primary magnet is composed of opposite magnetic poles having opposite magnetization directions on respective sides of a first boundary, and the first primary magnet, A first cross-flux magnet embedded in the first primary magnet through the opening in the first yoke, joined to the first primary magnet, and having a proximal side adjacent to the first yoke, wherein the cross-flux magnet is configured to have a magnetization direction substantially perpendicular to the magnetization direction of the first primary magnet, and the first cross-flux magnet, A second yoke having an opening, wherein the opening is plugged by a second plug, and the second yoke, A second primary magnet joined to the second yoke, having a proximal side adjacent to the second yoke and an opposing distal side, wherein the second primary magnet is composed of opposite magnetic poles having opposite magnetization directions on respective sides of a second boundary, and the second primary magnet, A second cross-flux magnet embedded in the second primary magnet through the opening in the second yoke, joined to the second primary magnet, and having a proximal side adjacent to the second yoke, wherein the cross-flux magnet is configured to have a magnetization direction substantially perpendicular to the magnetization direction of the second primary magnet, and a voice coil motor (VCM) comprising the second cross-flux magnet. (Item 12) The VCM of item 11, wherein the first cross-flux magnet is substantially embedded at the first boundary and the second cross-flux magnet is substantially embedded at the second boundary. (Item 13) A first channel extending from the proximal side to the distal side of the first primary magnet but not extending to the distal side of the first primary magnet, in which the first cross-flux magnet is embedded. A second channel that extends from the proximal side to the distal side of the second primary magnet but does not extend to the distal side of the second primary magnet and in which the second cross-flux magnet is embedded, and the VCM according to item 11 further comprising the second channel. (Item 14) The VCM according to item 13, wherein the first channel extends from the front side to the rear side of the first primary magnet, and the second channel extends from the front side to the rear side of the second primary magnet. (Item 15) The VCM according to item 11, wherein the first yoke and the first plug are made of the same material. (Item 16) A plurality of disk media rotatably attached to a spindle motor, A plurality of head sliders, each housing a read-write transducer configured to perform reading and writing between each of the plurality of disk media and the respective disk media, A voice coil motor (VCM) assembly configured to move the plurality of head sliders to access a portion of the plurality of disk media, A first yoke having an opening, the opening being plugged by a first plug made of the same material as the first yoke, the first yoke, A first primary magnet joined to the first yoke, having a proximal side adjacent to the first yoke and an opposing distal side, the first primary magnet being composed of opposing magnetic poles having opposite magnetization directions on respective sides of a first boundary, the first primary magnet, A first cross-flux magnet embedded in the first primary magnet through the opening in the first yoke, joined to the first primary magnet, and having a proximal side adjacent to the first yoke, the first cross-flux magnet being configured to have a magnetization direction substantially perpendicular to the magnetization direction of the first primary magnet, the first cross-flux magnet, A second yoke having an opening, the opening being plugged by a second plug made of the same material as the second yoke, the second yoke, A second primary magnet joined to the second yoke, having a proximal side adjacent to the second yoke and an opposing distal side, the second primary magnet being composed of opposing magnetic poles having opposite magnetization directions on respective sides of a second boundary, the second primary magnet, A second cross-flux magnet that is embedded in the second primary magnet through the opening in the second yoke, joined to the second primary magnet, and has a proximal side adjacent to the second yoke, wherein the second cross-flux magnet is configured to have a magnetization direction that is substantially perpendicular to the magnetization direction of the second primary magnet; and a VCM assembly comprising the second cross-flux magnet; a hard disk drive (HDD) comprising the VCM assembly. (Item 17) The HDD according to Item 16, wherein the magnetization direction of the first cross-flux magnet is opposite to the magnetization direction of the second cross-flux magnet. (Item 18) The HDD according to Item 16, wherein the first cross-flux magnet is substantially embedded at the first boundary, and the second cross-flux magnet is substantially embedded at the second boundary. (Item 19) A first channel that extends from the proximal side to the distal side of the first primary magnet but does not extend to the distal side of the first primary magnet and in which the first cross-flux magnet is embedded; The HDD according to Item 16, further comprising a second channel that extends from the proximal side to the distal side of the second primary magnet but does not extend to the distal side of the second primary magnet and in which the second cross-flux magnet is embedded.

Claims

1. A first yoke having an opening, wherein the opening is plugged by a first plug, and 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, wherein the first primary magnet is composed of opposing magnetic poles having opposite magnetization directions on respective sides of a first boundary, and the first primary magnet; A first cross-flux magnet embedded in the first primary magnet through the opening in the first yoke, joined to the first primary magnet, and having a proximal side adjacent to the first yoke, wherein the first cross-flux magnet is configured to have a magnetization direction substantially perpendicular to the magnetization direction of the first primary magnet, and the first cross-flux magnet; A second yoke having an opening, wherein the opening is plugged by a second plug, and the second yoke; A second primary magnet joined to the second yoke, having a proximal side adjacent to the second yoke, and having an opposing distal side, wherein the second primary magnet is composed of opposing magnetic poles having opposite magnetization directions on respective sides of a second boundary, and the second primary magnet; A second cross-flux magnet embedded in the second primary magnet through the opening in the second yoke, joined to the second primary magnet, and having a proximal side adjacent to the second yoke, wherein the second cross-flux magnet is configured to have a magnetization direction substantially perpendicular to the magnetization direction of the second primary magnet, and the second cross-flux magnet, a voice coil motor (VCM) comprising the same.

2. The VCM according to claim 1, wherein the first cross-flux magnet is substantially embedded at the first boundary, and the second cross-flux magnet is substantially embedded at the second boundary.

3. A first channel extending from the proximal side to the distal side of the first primary magnet but not extending to the distal side of the first primary magnet, in which the first cross-flux magnet is embedded; A second channel extending from the proximal side to the distal side of the second primary magnet but not extending to the distal side of the second primary magnet, in which the second cross-flux magnet is embedded, the VCM according to claim 1 further comprising the same.

4. The VCM according to claim 3, wherein the first channel extends from the front side to the rear side of the first primary magnet, and the second channel extends from the front side to the rear side of the second primary magnet.

5. The VCM according to claim 1, wherein the first yoke and the first plug are made of the same material.

6. A plurality of disk media rotatably attached to a spindle motor, A plurality of head sliders, each housing a read-write transducer configured to perform reading and writing between each of the plurality of disk media and the respective disk media, A voice coil motor (VCM) assembly configured to move the plurality of head sliders to access a portion of the plurality of disk media, A first yoke having an opening, the opening being plugged by a first plug made of the same material as the first yoke, 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 composed of opposing magnetic poles having opposite magnetization directions on respective sides of a first boundary, the first primary magnet, A first cross-flux magnet embedded in the first primary magnet through the opening in the first yoke, joined to the first primary magnet, and having a proximal side adjacent to the first yoke, the first cross-flux magnet being configured to have a magnetization direction substantially perpendicular to the magnetization direction of the first primary magnet, the first cross-flux magnet, A second yoke having an opening, the opening being plugged by a second plug made of the same material as the second yoke, the second yoke, A second primary magnet joined to the second yoke, having a proximal side adjacent to the second yoke, and having an opposing distal side, the second primary magnet being composed of opposing magnetic poles having opposite magnetization directions on respective sides of a second boundary, the second primary magnet, A second cross-flux magnet that is embedded in the second primary magnet through the opening in the second yoke, joined to the second primary magnet, and has a proximal side adjacent to the second yoke, wherein the second cross-flux magnet is configured to have a magnetization direction that is substantially perpendicular to the magnetization direction of the second primary magnet; and a VCM assembly comprising the second cross-flux magnet; A hard disk drive (HDD) comprising the VCM assembly. **Claim 7** The HDD according to claim 6, wherein the magnetization direction of the first cross-flux magnet is opposite to the magnetization direction of the second cross-flux magnet. **Claim 8** The HDD according to claim 6, wherein the first cross-flux magnet is substantially embedded at the first boundary, and the second cross-flux magnet is substantially embedded at the second boundary. **Claim 9** A first channel that extends from the proximal side to the distal side of the first primary magnet but does not extend to the distal side of the first primary magnet and in which the first cross-flux magnet is embedded; A second channel that extends from the proximal side to the distal side of the second primary magnet but does not extend to the distal side of the second primary magnet and in which the second cross-flux magnet is embedded; The HDD according to claim 6, further comprising the second channel.

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