Voice coil motor composite magnet assembly including low coercivity magnetic material

Abstract

A voice coil motor (VCM) includes: a coil; and a first yoke on the first side, the first yoke having a coil side facing the coil; a first low-coercivity permanent magnet located between the coil and a coil side of the first yoke, and having a yoke side facing the first yoke and a coil side opposite to the yoke side; and a first high-coercivity permanent magnet adjacent to the coil side of the first low-coercivity magnet. Second sides of the VCM on opposite sides of the coil are similarly configured. The magnetic conductance of such a VCM enables magnetic stability of low coercivity magnetic materials. Additional high-coercivity permanent magnets may be bonded to the coil side of each of the first and second yokes and adjoin the yoke side of each of the low-coercivity permanent magnets, if the relative thickness of the magnet material is thus determined by design.

Description

Technical Field

[0001] Embodiments of the present invention relate generally to voice coil motors and, more particularly, to hard disk drive rotary voice coil actuators having composite magnet assemblies including low coercivity magnetic materials. Background Art

[0002] A hard disk drive (HDD) is a non-volatile storage device that is housed in a protective housing and stores digitally encoded data on one or more disks with a magnetic surface. When the 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 disk using a read-write head (or "transducer") housed in a slider that is positioned above 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 operates using an electric current flowing through its coil, thereby generating a magnetic field. Electrical pulses are sent to the write head in different patterns of positive and negative currents. The current in the coil of the write head generates a local magnetic field in the gap between the head and the magnetic recording disk, which in turn magnetizes a small area on the recording medium.

[0003] Voice coil motors ("VCMs") are typically the type of actuator used in HDDs to move the read-write head to access portions of the corresponding magnetic recording disk for read and write operations. VCMs rely on permanent magnets to achieve their own persistent magnetic fields. This field is typically strongest at the surface of the magnet and decreases with distance from it, so the magnetic flux density also decreases with distance from the magnet. In addition, the cost of permanent magnets is typically relative to the corresponding grade of the magnet and the material from which the magnet is made, with higher grades indicating stronger magnets. Rare earth magnets are strong permanent magnets made from alloys of rare earth elements, such as typical neodymium magnets and samarium-cobalt magnets. Historically, rare earth magnets have been implemented in HDD VCMs because such magnets are the strongest type of permanent magnets manufactured, producing significantly stronger magnetic fields than other types. In addition to price issues, there are also environmental issues regarding rare earth materials because they are typically extracted from ores that may contain radioactive materials such as thorium, and large amounts of carcinogenic compounds such as ammonia, hydrochloric acid, and sulfates are typically used to extract the required rare earths. In view of the foregoing, alternatives to rare earth magnetic materials for use in HDD VCMs may be desirable.

[0004] Any approaches described in this section are approaches that could be pursued, but are not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any approaches described in this section qualify as prior art merely by virtue of their inclusion in this section. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Embodiments are illustrated by way of example and not limitation in the accompanying drawings in which like reference numerals refer to similar elements and in which:

[0006] Figure 1 is a plan view showing a hard disk drive (HDD) according to one embodiment;

[0007] Figure 2A is a perspective view showing a composite magnet assembly for a voice coil motor according to one embodiment;

[0008] Figure 2B It is shown that according to one embodiment Figure 2A A side view of a composite magnet assembly;

[0009] Figure 3A is a side view showing a single skin composite magnet assembly for a voice coil motor (VCM) according to one embodiment;

[0010] Figure 3B is a side view showing a double-skin composite magnet assembly for a voice coil motor (VCM) according to one embodiment;

[0011] Figure 4 is a flow chart illustrating a method of assembling a voice coil motor according to one embodiment; and

[0012] Figure 5 is a flow chart illustrating a method of assembling a voice coil motor according to one embodiment. DETAILED DESCRIPTION

[0013] Generally, methods of voice coil motor (VCM) actuators having a composite magnet assembly including a low coercivity magnetic material, such as for use in a hard disk drive (HDD), are 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 can 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.

[0014] introduction

[0015] the term

[0016] Reference herein to "an embodiment," "one embodiment," etc., is intended to mean that a particular feature, structure, or characteristic being described is included in at least one embodiment of the present invention. However, instances of such phrases are not necessarily all referring to the same embodiment.

[0017] The term "substantially" should be understood to describe a feature that is mostly or nearly structured, constructed, dimensioned, etc., but in practice manufacturing tolerances, etc. cause the structure, configuration, dimensions, etc. not always or necessarily to be exactly as described. For example, describing a structure as "substantially vertical" would give the term its ordinary meaning, such that the sidewalls are vertical for all practical purposes, but may not be exactly at 90 degrees throughout.

[0018] While terms such as "best," "optimize," "minimum," "minimize," "maximum," "maximize," etc. may not have certain values ​​associated with them, if such terms are used herein, it is intended that one of ordinary skill in the art will understand that such terms will include affecting values, parameters, metrics, etc. in beneficial directions consistent with the present disclosure as a whole. For example, describing a value of something as "minimum" does not require that the value actually equal some theoretical minimum value (e.g., zero), but should be understood in a practical sense that the corresponding goal is to move the value in a beneficial direction toward the theoretical minimum value.

[0019] Context

[0020] Recall that alternatives to rare earth magnetic materials used in HDD VCMs may be desirable. New classes of magnetic materials are entering the market in which certain rare earth materials are reduced or eliminated. While capable of achieving significant performance, these materials suffer from a relatively low magnetic coercivity (H) compared to existing solutions. C , i.e., a measure of the ability of a ferromagnetic material to withstand an external magnetic field without demagnetization). This property is combined with the relatively low permeability (P) of a typical VCM design. C , that is, magnetic flux density B d With magnetic field strength H d The ratio of the coercivity to the magnet's operating point on the BH curve, or the "operating slope," or essentially the efficiency with which the material is utilized, combined with the above, presents challenges for the implementation of this new class of magnetic materials. In particular, low coercivity magnetic materials at relatively low P C The risk of demagnetization in applications where the system P C Mainly determined by the geometry of the system components, such as the pancake shape of a typical HDD VCM.

[0021] Composite magnet assemblies for voice coil motors

[0022] Therefore, one challenge identified with implementing low-coercivity magnetic materials in HDD VCMs is how to increase the permeability of such VCMs to enable the magnetic stability of these newer magnetic materials. According to one embodiment, the weakest region of the low-coercivity magnet is effectively replaced with a high-coercivity magnet, where the outer surface of the magnet is at P CIn other words, this approach effectively replaces the material in the unstable region (of low coercivity material) with a more stable high coercivity material.

[0023] Figure 2A is a perspective view showing a composite magnet assembly for a voice coil motor according to one embodiment, and Figure 2B It is shown that according to one embodiment Figure 2A 200 is a side view of a composite magnet assembly. The assembly 200 includes: a first yoke 202a (e.g., a steel plate) having an air side, or a coil side facing a coil (not shown here) when installed; a first low-coercive force permanent magnet 204a, which is located between the coil and the coil side of the first yoke 202a and has a yoke side facing the first yoke 202a and a coil side opposite the yoke side; and a first high-coercive force permanent magnet 205a, which is adjacent to the coil side of the first low-coercive force magnet 204a. Similarly, the other side of the assembly 200 includes: a second yoke 202b having an air side or a coil side facing the coil when installed; a second low-coercive force permanent magnet 204b located between the coil and the coil side of the second yoke 202b and having a yoke side facing the second yoke 202b and a coil side opposite the yoke side; and a second high-coercive force permanent magnet 205b adjacent to the coil side of the second low-coercive force magnet 204b. Each of the permanent magnets 204a, 205a, 204b, 205b includes a permanent magnet magnetized to have a north magnetic pole and an adjacent south magnetic pole on a respective side of the boundary. The assembly 200 is designed to be a component of a voice coil motor (VCM), such as for use in a hard disk drive (see, e.g. Figure 1 The voice coil motor will also include a coil located between the two sides of the component 200 (see, for example, Figure 3A-3B Thus, the volume of magnetic material in the weakest region of each relatively magnetically unstable low-coercivity magnet 204a, 204b is effectively replaced by the volume of magnetic material of the corresponding magnetically stable high-coercivity magnet 205a, 205b. Note that in contrast to the Hallbach array magnet arrangement, the Hallbach array is configured to increase the magnetic field and thus compromise / reduce P C , which is contrary to the intended purpose of the embodiments described herein. In addition, the Hallbach array specifically requires magnetic components whose magnetic fields are oriented substantially perpendicular to the magnetic field of the main magnet, whereas here, according to the embodiments, the high-coercivity magnetic field and the low-coercivity magnetic field are aligned.

[0024] For non-limiting example, a “low-coercive force magnet” such as each of the low-coercive force magnets 204 a , 204 b refers to a magnet having a magnetic normal coercive force (H ) of less than about 10,000 Oersteds (10 kOe) at ambient temperature. Cn), and a "high coercive force magnet" such as each high coercive force magnet 205a, 205b refers to a permanent magnet having a magnetic normal coercive force (H) greater than about 10,000 Oersted (10 kOe) at ambient temperature. Cn ) of the permanent magnet. In addition, while the shape, profile, and footprint of each high-coercive force magnet 205a, 205b preferably substantially covers the area of ​​the corresponding low-coercive force magnet 204a, 204b, the corresponding permanent magnet shapes are not necessarily the same and may vary according to different specific implementations. For example, if the high-coercive force magnet has a slightly smaller footprint / profile than the low-coercive force magnet while maintaining suitability for the intended purpose, such as about 1 millimeter (mm) smaller around the perimeter of the high-coercive force magnet, material cost savings can be achieved.

[0025] Figure 3A 300 is a side view showing a single-skin composite magnet assembly for a voice coil motor (VCM) according to one embodiment. Assembly 300 is generally referred to herein as a "single-skin" magnet assembly because only a single high-coercivity magnet 205a, 205b is used to cover and improve the efficiency and stability of each corresponding low-coercivity magnet 204a, 204b, whereby single-skin assembly 300 is similar to assembly 200 ( Figure 2A-2B ) is configured, and similarly, the component 200 is composed of Figure 3AThus, the assembly 300 includes a first yoke 302a (e.g., a steel plate) having a coil side 302a-c facing the coil 306, a first low-coercive force permanent magnet 304a located between the coil 306 and the coil side 302a-c of the first yoke 302a and having a yoke side 304a-y facing the first yoke 302a and a coil side 304a-c opposite to the yoke side 304a-y, and a first high-coercive force permanent magnet 305a adjacent to the coil side 304a-c of the first low-coercive force magnet 304a. Similarly, the other side of the component 300 includes a second yoke 302b (e.g., a steel plate) having a coil side 302b-c facing the coil 306, a second low-coercive force permanent magnet 304b located between the coil 306 and the coil side 302b-c of the second yoke 302b and having a yoke side 304b-y facing the second yoke 302b and a coil side 304b-c opposite to the yoke side 304b-y, and a second high-coercive force permanent magnet 305b adjacent to the coil side 304b-c of the second low-coercive force magnet 304b. According to one embodiment, each of the first high-coercive force permanent magnet 305a and the second high-coercive force permanent magnet 305b includes a rare earth element (for non-limiting examples, a neodymium-based alloy such as NdFeB or a samarium-based alloy such as SmCo or SmFeN), and each of the first low-coercive force permanent magnet 304a and the second low-coercive force permanent magnet 304b includes a non-rare earth element (for non-limiting examples, an iron nitride-based alloy or an iron-nickel-based alloy). In addition, each of the first low-coercive force permanent magnet 304a and the second low-coercive force permanent magnet 304b may include a reduced rare earth magnet, whereby a relatively small amount of rare earth material (e.g., Nd) is still used but is mostly / primarily replaced by another element, and / or other rare earth elements are eliminated and replaced by other elements. It should be noted that the aforementioned permanent magnet composition is given as a non-limiting example because such low-coercive force permanent magnets are still under development.

[0026] Thus, according to one embodiment, the first low-coercive force permanent magnet 304a is bonded to (or adhered, attached or otherwise coupled to) the coil side 302a-c of the first magnetic yoke 302a, and the second low-coercive force permanent magnet 304b is bonded to (or adhered, attached or otherwise coupled to) the coil side 302b-c of the second magnetic yoke 302b. Continuing and according to one embodiment, the first high-coercive force permanent magnet 305a is similarly bonded to the coil side 304a-c of the first low-coercive force magnet 304a, and the second high-coercive force permanent magnet 305b is similarly bonded to the coil side 304b-c of the second low-coercive force magnet 304b.

[0027] For the single skin embodiment of the assembly 300, the P on the air side (also referred to as the coil side 304a-c, 304b-c) of each low coercivity permanent magnet 304a, 304b isC Lower than P on the steel side (also referred to as the yoke side 304a-y, 304b-y) C , which is an inherent feature of the magnetic circuit. At some point in the increasingly thick high-coercivity permanent magnet 305a, 305b design (and commensurately increasingly thin low-coercivity permanent magnet 304a, 304b, thereby maintaining the overall magnet thickness), the air side of each low-coercivity permanent magnet 304a, 304b is no longer a limiting point (i.e., the P of the air side surface C becomes larger than P on the yoke side surface C ). Instead, for stability purposes, the system will now not be constrained at the interface of the low-coercivity / high-coercivity permanent magnets 304a / 305a, 304b / 305b, but rather by the interface of each low-coercivity permanent magnet 304a, 304b and the corresponding steel plate (also referred to as the yoke 302a, 302b). Therefore, at this design point (for a non-limiting example, P C Approaching 1.2), the design limit is reached, and therefore a double skin or "sandwich" design is preferred to continue to improve magnetic system stability.

[0028] Figure 3B is a side view showing a double skin composite magnet assembly for a voice coil motor (VCM) according to one embodiment. The assembly 350 is generally referred to herein as a "double skin" magnet assembly because a pair of high coercivity magnets 355a / 357a, 355b / 357b is used to sandwich each corresponding low coercivity magnet 354a, 354b and further improve its efficiency and stability. Thus, the component 350 includes a first yoke 352a (e.g., a steel plate) having a coil side 352a-c facing the coil 356, a first low-coercive force permanent magnet 354a located between the coil 356 and the coil side 352a-c of the first yoke 352a and having a yoke side 354a-y facing the first yoke 352a and a coil side 354a-c opposite to the yoke side 354a-y, and a first high-coercive force permanent magnet 355a adjacent to the coil side 354a-c of the first low-coercive force magnet 354a. Similarly, the other side of the component 350 includes a second yoke 352b (e.g., a steel plate) having a coil side 352b-c facing the coil 356, a second low-coercive force permanent magnet 354b located between the coil 356 and the coil side 352b-c of the second yoke 352b and having a yoke side 354b-y facing the second yoke 352b and a coil side 354b-c opposite to the yoke side 354b-y, and a second high-coercive force permanent magnet 355b adjacent to the coil side 354b-c of the first low-coercive force magnet 354b.

[0029] According to one embodiment, the assembly 350 also includes: a third high-coercive force permanent magnet 357a, which is bonded (or adhered, attached or otherwise coupled) to the coil side 352a-c of the first yoke 352a and adjacent to the yoke side 354a-y of the first low-coercive force permanent magnet 354a; and a fourth high-coercive force permanent magnet 357b, which is bonded (or adhered, attached or otherwise coupled) to the coil side 352b-c of the second yoke 352b and adjacent to the yoke side 354b-y of the second low-coercive force permanent magnet 354b. In this way, and according to one embodiment, the first low-coercive force permanent magnet 354a is bonded to the coil side 357a-c of the third high-coercive force permanent magnet 357a, and the second low-coercive force permanent magnet 354b is bonded to the coil side 357b-c of the fourth high-coercive force permanent magnet 357b. Continuing and according to one embodiment, the first high-coercive force permanent magnet 355a is coupled to the coil sides 354a-c of the first low-coercive force permanent magnet 354a, and the second high-coercive force permanent magnet 355b is coupled to the coil sides 354b-c of the second low-coercive force permanent magnet 354b.

[0030] for Figure 3A Component 300, with respect to the relative thickness of each low-coercive force permanent magnet 304a, 304b, 354a, 354b and each corresponding high-coercive force permanent magnet 305a, 305b, 355a / 357a, 355b / 357b, most of the magnet volume is retained in the corresponding low-coercive force permanent magnet 304a, 304b, 354a, 354b. For a non-limiting example, a suitable thickness ratio for a single skin configuration may be approximately 25%-33% high-coercive force permanent magnet (skin) to 67%-75% low-coercive force permanent magnet (core). For another non-limiting example in the case of a double skin configuration, a suitable thickness ratio may be approximately 33% for each of the high-coercive force and low-coercive force permanent magnets (core and each of the two skins), and up to approximately 50% for the low-coercive force permanent magnet (core). Above those high coercivity permanent magnet thicknesses, this approach is considered less beneficial or has diminishing returns.

[0031] How to assemble a voice coil motor

[0032] Figure 4 is a flow chart showing a method of assembling a voice coil motor according to one embodiment. For example, Figure 4 The method can be used to assemble a VCM having a composite magnet as shown and described elsewhere herein. That is, Figure 4 The method can be used to assemble a composite magnet 204a / 205a, 204b / 205b ( Figure 2A-2B ) and / or composite magnets 304a / 305a, 304b / 305b ( Figure 3A )’s VCM.

[0033] At block 402, a first low-coercive force permanent magnet material is bonded to a coil side of a first magnetic yoke, wherein the first low-coercive force permanent magnet material has a yoke side facing the first magnetic yoke and a coil side opposite the yoke side. Figure 2A-2B )、304a( Figure 3A ) is bonded to the first yoke 202a ( Figure 2A-2B )、302a( Figure 3A ) coil side ( Figure 2A-2B )302a-c( Figure 3A ), wherein the first low coercive force permanent magnet material 204a, 304a has a yoke side facing the first yoke 202a, 302a ( Figure 2A-2B )304a-y( Figure 3A ) and the coil side opposite to the yoke side 304a-y ( Figure 2A-2B )304a-c( Figure 3A ).

[0034] At block 404, a first high coercive force permanent magnet material is bonded to the coil side of the first low coercive force magnet material. For example, the first high coercive force permanent magnet 205a ( Figure 2A-2B )、305a( Figure 3A ) material is bonded to the coil sides 304a-c of the first low-coercive force magnets 204a, 304a.

[0035] At block 406, the first low-coercive force permanent magnet material and the first high-coercive force permanent magnet material are magnetically charged to form the first low-coercive force permanent magnet and the first high-coercive force permanent magnet. For example, the material of the first low-coercive force permanent magnet 204a, 304a and the material of the first high-coercive force permanent magnet 205a, 305a are appropriately charged when they are combined with the first magnetic yoke 202a, 302a to form the first low-coercive force permanent magnet 204a, 304a and the first high-coercive force permanent magnet 205a, 305a.

[0036] Similarly, blocks 402 - 406 may be performed to assemble a similar half assembly for opposing magnet-yoke portions of a VCM for assembly with another similar half assembly to form a VCM top-bottom pair.

[0037] Figure 5 is a flow chart showing a method of assembling a voice coil motor according to one embodiment. For example, Figure 5 The method can be used to assemble a VCM having a composite magnet as shown and described elsewhere herein. That is, Figure 5 The method can be used to assemble a composite magnet 357a / 354a / 355a, 357b / 354b / 355b ( Figure 3B )’s VCM.

[0038] At block 502, a first high coercive force permanent magnet material is bonded to a coil side of a first magnetic yoke, wherein the first high coercive force permanent magnet material has a yoke side facing the first magnetic yoke and a coil side opposite the yoke side. Figure 3B ) is bonded to the first yoke 352a ( Figure 3B ) of the coil side 352a-c ( Figure 3B ).

[0039] At block 504, a first low-coercive force permanent magnet material is bonded to the coil side of the first high-coercive force permanent magnet material, wherein the first low-coercive force permanent magnet material has a yoke side facing the first yoke and a coil side opposite the yoke side. Figure 3B ) is bonded to the material of the first high coercive force permanent magnet 357a.

[0040] At block 506, a second high coercive force permanent magnet material is bonded to the coil side of the first low coercive force magnet material. For example, the second high coercive force permanent magnet 355a ( Figure 3B ) is bonded to the material of the first low-coercive force permanent magnet 354a.

[0041] In box 508, the first low-coercive force permanent magnet material and the first high-coercive force permanent magnet material and the second high-coercive force permanent magnet material are magnetically charged to form the first low-coercive force permanent magnet, the first high-coercive force permanent magnet and the second high-coercive force permanent magnet. For example, the material of the first low-coercive force permanent magnet 354a and the material of the first high-coercive force permanent magnet 355a and the second high-coercive force permanent magnet 357a are appropriately charged when combined with the first magnetic yoke 352a to form the first low-coercive force permanent magnet 354a and the first high-coercive force permanent magnet 355a and the second high-coercive force permanent magnet 357a.

[0042] Similarly, blocks 502 - 508 may be performed to assemble a similar half assembly for opposing magnet-yoke portions of a VCM for assembly with another similar half assembly to form a VCM top-bottom pair.

[0043] By the above method, the volume of magnetic material in the weakest region of each relatively magnetically unstable low-coercivity magnet is effectively replaced by the volume of magnetic material of the corresponding magnetically stable high-coercivity magnet. This enables the implementation of low-coercivity (e.g., non-rare earth or reduced rare earth) magnetic materials in HDD VCMs, with associated cost and / or environmental savings, while maintaining suitable permeability by achieving magnetic stability of these newer magnetic materials.

[0044] Physical Description of an Illustrative Operational Context

[0045] 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, Figure 1 A plan view illustrating a conventional HDD 100 is shown to help describe how a conventional HDD generally operates.

[0046] Figure 1 The functional arrangement of components of the HDD 100 including a slider 110b including a magnetic read-write head 110a is shown. The slider 110b and the head 110a may be collectively referred to as a head slider. The HDD 100 includes at least one head gimbal assembly (HGA) 110 having a head slider, a lead suspension 110c attached to the head slider typically via a flexure, and a load beam 110d attached to the lead suspension 110c. The HDD 100 also includes at least one recording medium 120 rotatably mounted on a spindle 124 and a drive motor (not visible) 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 respectively writing and reading information stored on the medium 120 of the HDD 100. The medium 120 or multiple disk media may be attached to the spindle 124 using a disk clamp 128.

[0047] The HDD 100 also 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 visible). 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 the portion of the media 120, which are collectively mounted on a pivot shaft 148 with an interposed pivot bearing assembly 152. In the case of an HDD having multiple disks, the carriage 134 may be referred to as an "E-block" or comb because the carriage is arranged to carry an array of linked arms, giving it the appearance of comb teeth.

[0048] The assembly including a head gimbal assembly (e.g., HGA110) having 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 also includes an electrical interconnect component. Generally speaking, the HSA is an assembly that is configured to move a head slider to access portions of the medium 120 for read and write operations.

[0049] Further references Figure 1, electrical signals including write signals to the head 110a and read signals from the head (e.g., current to the voice coil 140 of the VCM) are transmitted by a flexible cable assembly (FCA) 156 (or "flexible cable", or "flexible printed circuit" (FPC)). The interconnect between the flexible cable 156 and the head 110a may include an arm electronics (AE) module 160, which may have an onboard preamplifier for the read signal and other read channel and write channel electronic components. The AE module 160 may be attached to the carriage 134, as shown. The flexible cable 156 may be coupled to an electrical connector block 164, which in some configurations provides electrical connectivity through an electrical feed-through provided by the HDD housing 168. The HDD housing 168 (or "housing base" or "baseboard" or "motor base assembly" or simply "base") together with the HDD cover provides a semi-sealed (or hermetically sealed, in some configurations) protective housing for the information storage components of the HDD 100.

[0050] 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 coil 140 of the VCM, and the head 110a of the HGA 110. The electrical signal provided to the drive motor causes the drive motor to rotate, thereby providing torque to the spindle 124, which in turn 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 forms an air cushion 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 making contact with the thin magnetic recording layer that records information. Similarly, in an HDD that utilizes a lighter-than-air gas (such as helium for non-limiting example), the rotating medium 120 forms an air cushion that acts as a gas or fluid bearing on which the slider 110b rides.

[0051] 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 the information is recorded. As a result, the armature 136 of the VCM swings through the arc 180, which enables the head 110a of the HGA 110 to access the individual tracks on the medium 120. The information is stored in a plurality of radially nested tracks on the medium 120, which are arranged in sectors (such as sector 184) on the medium 120. Accordingly, each track is composed of a plurality of sectorized track portions (or "track sectors") such as sectorized track portion 188. Each sectorized track portion 188 may include recorded information and a data header containing 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 a servo burst signal pattern which provides a position error signal (PES) to the servo electronics, which in turn controls an electrical signal provided to the voice coil 140 of the VCM, thereby enabling head 110a to follow track 176. Upon finding track 176 and identifying a particular sectorized track portion 188, head 110a either reads information from track 176 or writes information to track 176 in accordance with instructions received by the disk controller from an external agent, such as a microprocessor of a computer system.

[0052] The electronic architecture of the HDD includes multiple electronic components for performing their respective HDD operating functions, 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 such components may be combined on a single integrated circuit board called 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 the HDD, such as to the HDD housing 168.

[0053] Reference herein to hard disk drives, such as reference Figure 1The HDD 100 shown and described may include an information storage device sometimes referred to as a "hybrid drive." A hybrid drive generally refers to a storage device that has the functionality of a conventional HDD (see, for example, HDD 100) combined with a solid-state storage device (SSD) that uses non-volatile memory, such as flash memory or other solid-state (e.g., integrated circuit) memory, which is electrically erasable and programmable. Because the operation, management, and control of different types of storage media are generally different, the solid-state portion of the hybrid drive may include its own corresponding controller functionality, which may be integrated into a single controller along with the HDD functionality. The hybrid drive may be constructed and configured to operate and utilize the solid-state portion in a variety of ways, such as, as a non-limiting example, using the solid-state memory as a cache memory, for storing frequently accessed data, for storing I / O intensive data, and the like. In addition, the hybrid drive may be constructed and configured to be essentially two storage devices in a single housing, namely a conventional HDD and an SSD, with one or more interfaces for host connection.

[0054] Extensions and replacements

[0055] In the foregoing description, embodiments of the present invention have been described with reference to a large number of specific details, which may vary according to different specific implementations. Therefore, various modifications and changes may be made to the embodiments without departing from the broader essence and scope of the embodiments. Therefore, the present invention and the applicant's sole and exclusive indicator of the present invention are a set of claims issued by this patent application in the specific form in which such claims are issued, including any subsequent corrections. Any definition of the terms contained in these claims explicitly set forth herein should determine the meaning of these terms used in the claims. Thus, limitations, elements, characteristics, features, advantages or attributes that are not explicitly cited in the claims should not limit the scope of this claim in any way. Therefore, this specification and the drawings are considered to be illustrative rather than restrictive.

[0056] Additionally, in this description, certain process steps may be shown in a particular order, and letters and alphanumeric labels may be used to identify certain steps. Unless expressly indicated in the specification, the embodiments are not necessarily limited to any particular order of performing such steps. In particular, these labels are used only to facilitate identification of the steps and are not intended to specify or require a particular order of performing such steps.

Claims

1. A voice coil motor (VCM), comprising: Coil; a first yoke having a coil side facing the coil; a first low-coercive force permanent magnet located between the coil and the coil side of the first yoke and having a yoke side facing the first yoke and a coil side opposite to the yoke side; a first high-coercive force permanent magnet, the first high-coercive force permanent magnet being adjacent to the coil side of the first low-coercive force magnet; a second yoke having a coil side facing the coil; a second low-coercive force permanent magnet located between the coil and the coil side of the second yoke and having a yoke side facing the second yoke and a coil side opposite to the yoke side; A second high-coercive force permanent magnet is adjacent to the coil side of the second low-coercive force magnet. 2 . The VCM of claim 1 , wherein the first low-coercive force permanent magnet is coupled to the coil side of the first yoke, and the second low-coercive force permanent magnet is coupled to the coil side of the second yoke. 3 . The VCM of claim 2 , wherein the first high-coercive force permanent magnet is coupled to the coil side of the first low-coercive force permanent magnet, and the second high-coercive force permanent magnet is coupled to the coil side of the second low-coercive force permanent magnet.

4. The VCM of claim 1, further comprising: a third high-coercive force permanent magnet coupled to the coil side of the first yoke and adjacent to the yoke side of the first low-coercive force permanent magnet; and A fourth high-coercive-force permanent magnet is coupled to the coil side of the second yoke and is adjacent to the yoke side of the second low-coercive-force permanent magnet. 5 . The VCM of claim 4 , wherein the first low-coercive force permanent magnet is coupled to a coil side of the third high-coercive force permanent magnet, and the second low-coercive force permanent magnet is coupled to a coil side of the fourth high-coercive force permanent magnet. 6 . The VCM of claim 5 , wherein the first high-coercive force permanent magnet is coupled to the coil side of the first low-coercive force permanent magnet, and the second high-coercive force permanent magnet is coupled to the coil side of the second low-coercive force permanent magnet.

7. The VCM of claim 1, wherein: Each of the first high-coercive force permanent magnet and the second high-coercive force permanent magnet has a magnetic normal coercive force (HCn) greater than ten thousand Oersteds (10 kOe) at ambient temperature; and Each of the first low-coercive force permanent magnet and the second low-coercive force permanent magnet has a magnetic normal coercive force (H ) of less than 10 kOe (10 kOe) at ambient temperature. Cn ).

8. A hard disk drive (HDD), comprising: a plurality of magnetic disk media rotatably mounted on a spindle motor; a plurality of head sliders, each head slider housing a read-write transducer configured to read from and write to at least one disk medium of the plurality of disk media; and a voice coil motor (VCM) assembly configured to move the plurality of head sliders to access portions of the disk media, the VCM assembly comprising: Coil, a first yoke having a coil side facing the coil, a first low-coercive force permanent magnet, the first low-coercive force permanent magnet being located between the coil and the coil side of the first yoke and having a yoke side facing the first yoke and a coil side opposite to the yoke side, a first high-coercive force permanent magnet, the first high-coercive force permanent magnet being adjacent to the coil side of the first low-coercive force magnet, a second yoke having a coil side facing the coil, a second low-coercive force permanent magnet located between the coil and the coil side of the second yoke and having a yoke side facing the second yoke and a coil side opposite to the yoke side, A second high-coercive force permanent magnet is adjacent to the coil side of the second low-coercive force magnet. 9 . The HDD of claim 8 , wherein the first low-coercive force permanent magnet is coupled to the coil side of the first yoke, and the second low-coercive force permanent magnet is coupled to the coil side of the second yoke. 10 . The HDD of claim 9 , wherein the first high-coercive force permanent magnet is coupled to the coil side of the first low-coercive force permanent magnet, and the second high-coercive force permanent magnet is coupled to the coil side of the second low-coercive force permanent magnet.

11. The HDD according to claim 8, further comprising: a third high-coercive force permanent magnet coupled to the coil side of the first yoke and adjacent to the yoke side of the first low-coercive force permanent magnet; and A fourth high-coercive-force permanent magnet is coupled to the coil side of the second yoke and is adjacent to the yoke side of the second low-coercive-force permanent magnet. 12 . The HDD of claim 11 , wherein the first low-coercive force permanent magnet is coupled to a coil side of the third high-coercive force permanent magnet, and the second low-coercive force permanent magnet is coupled to a coil side of the fourth high-coercive force permanent magnet. 13 . The HDD of claim 12 , wherein the first high-coercive force permanent magnet is coupled to the coil side of the first low-coercive force permanent magnet, and the second high-coercive force permanent magnet is coupled to the coil side of the second low-coercive force permanent magnet.

14. The HDD according to claim 8, wherein: Each of the first high-coercive force permanent magnet and the second high-coercive force permanent magnet has a magnetic normal coercive force (HCn) greater than ten thousand Oersteds (10 kOe) at ambient temperature; and Each of the first low-coercive force permanent magnet and the second low-coercive force permanent magnet has a magnetic normal coercive force (H ) of less than 10 kOe (10 kOe) at ambient temperature. Cn ).

15. A method of assembling a voice coil motor (VCM), the method comprising: The first half of the assembly is formed by the following steps: bonding a first low-coercive force permanent magnet material to a coil side of a first yoke, wherein the first low-coercive force permanent magnet material has a yoke side facing the first yoke and a coil side opposite the yoke side; bonding a first high-coercivity permanent magnet material to the coil side of the first low-coercivity magnet material; as well as The first low-coercive force permanent magnet material and the first high-coercive force permanent magnet material are magnetically charged to form a first low-coercive force permanent magnet and a first high-coercive force permanent magnet.

16. The method according to claim 15, further comprising: forming a second half assembly according to the method of claim 15; as well as Assemble the first half assembly and the second half assembly together.

17. A voice coil motor assembled according to the method of claim 16.

18. A method of assembling a voice coil motor (VCM), the method comprising: The first half of the assembly is formed by the following steps: bonding a first high coercive force permanent magnet material to a coil side of a first yoke, wherein the first high coercive force permanent magnet material has a yoke side facing the first yoke and a coil side opposite the yoke side; bonding a first low-coercive force permanent magnet material to the coil side of the first high-coercive force permanent magnet material, wherein the first low-coercive force permanent magnet material has a yoke side facing the first yoke and a coil side opposite the yoke side; bonding a second high coercive force permanent magnet material to the coil side of the first low coercive force magnet material; as well as The first high-coercive force permanent magnet material, the first low-coercive force permanent magnet material and the second high-coercive force permanent magnet material are magnetically charged. To form a first high-coercive force permanent magnet, a first low-coercive force permanent magnet and a second high-coercive force permanent magnet.

19. The method according to claim 18, further comprising: forming a second half assembly according to the method of claim 17; as well as Assemble the first half assembly and the second half assembly together.

20. A voice coil motor assembled according to the method of claim 19.

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