Hard disk drive voice coil motor actuator with low-density wire coil and high-density coil reinforcement

Abstract

This invention provides a data storage device that controls the torsional mode of a coil and reduces the power consumption of an actuator. [Solution] A voice coil motor assembly (VCMA) 400 for hard disk drives and the like includes a low-density voice coil 407 and a high-density coil reinforcement 408 positioned inside the wire coil. The low-density voice coil, utilizing copper-clad aluminum or aluminum wire, increases the second coil torsion mode frequency of the VCMA, thereby bringing it closer to the second torsion mode frequency of the actuator arm 402. In addition, the high-density reinforcement, utilizing steel, copper, or zinc, increases the mass of the VCMA with respect to the center of mass of the VCMA around the rotation axis of the VCMA, compensating for the lower-density wire. With respect to the position error signal (PES) under customer box vibration conditions, significant peaks in the PES spectrum are largely eliminated, and the power of the PES is reduced by approximately half.

Description

Technical Field

[0001] Embodiments of the present invention generally relate to data storage devices such as hard disk drives, and more particularly to techniques for improving the structural mechanics of voice coil motor assemblies within hard disk drives.

Background Art

[0002] A hard disk drive (HDD) is a non-volatile memory device that stores digitally encoded data on one or more circular disks having a magnetic surface, housed within a protective enclosure. While 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 transducer (or read-write “head”) 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. Electrical pulses with different patterns of positive and negative currents are sent to the write head. The current in the coil of the write head generates a local magnetic field across the gap between the head and the magnetic disk, which then magnetizes a small area on the recording medium.

[0003] An HDD includes at least one head gimbal assembly (HGA), which generally includes a slider housing the read-write head and a suspension. Each slider is mounted to the free end of the suspension, which is then cantilevered from the rigid arms of the actuator. Several actuator arms can be combined to form a single movable unit, typically a head stack assembly (HSA) with a rotary pivot bearing system. The suspension of a conventional HDD typically includes a relatively rigid load beam with a mounting plate at its base end, the mounting plate is mounted to the actuator arm, and its free end carries the slider and the flexure that carries its read-write head.

[0004] As the number and capabilities of networked computing systems increase, more data storage system capacity is required. Cloud computing and large-scale data processing further increase the need for digital data storage systems that can transfer and hold large amounts of data. For this purpose, increasing the storage capacity of HDDs is one of the ongoing goals in the evolution of HDD technology. In modern HDDs, operational vibration (also called "customer box vibration") is one of the most important factors in track misregistration (TMR), which generally refers to the dispersion of the deviation of the read-write head from the center of the data track, i.e., where the track-following / servo head is located relative to where it is expected to be. The main causes of operational vibration are (a) acoustic excitation caused by air pressure fluctuations from the cooling fan, and (b) structurally transmitted external vibrations.

[0005] Any method described in this section is a feasible method, but not necessarily a previously devised or pursued method. Therefore, unless otherwise indicated, none of the methods described in this section should be assumed to be eligible as prior art simply by being included in this section. [Brief explanation of the drawing]

[0006] Embodiments are shown in the accompanying drawings as examples, not as limitations, and in the drawings, similar reference numerals refer to similar elements. [Figure 1] This is a plan view showing a hard disk drive (HDD) according to an embodiment. [Figure 2] This is a perspective view showing a voice coil motor (VCM) assembly according to an embodiment. [Figure 3A] This is a perspective view showing the structural mechanics of a VCM assembly. [Figure 3B] Figure 3A is a diagram showing the second coil torsion mode of the VCM assembly. [Figure 4] This is a perspective view showing a VCM assembly according to an embodiment. [Figure 5] This is a flowchart illustrating a method for manufacturing a voice coil motor assembly according to an embodiment. [Modes for carrying out the invention]

[0007] In general, this document describes techniques for improving the structural mechanics of actuator systems within hard disk drives. The following description includes numerous specific details for illustrative purposes to provide a complete understanding of the embodiments of the invention described herein. However, it will be apparent that the embodiments of the invention described herein can be carried out without these specific details. In other cases, well-known structures and devices may be shown in block diagram form to avoid unnecessarily obscuring the embodiments of the invention described herein.

[0008] Introduction term References to “an embodiment,” “one embodiment,” etc., in this specification are intended to mean that the specific features, structures, or characteristics described are included in at least one embodiment of the present invention. However, the appearance of such phrases does not necessarily mean that all instances refer to the same embodiment.

[0009] The term "substantially" is understood to describe features such as being largely or almost entirely structured, configured, or dimensioned, but manufacturing tolerances, etc., can actually result in situations where the structure, configuration, dimensions, etc., are not always or not exactly as described. For example, if a structure is described as "substantially perpendicular," the term is assigned its obvious meaning, such as the structure being perpendicular for all practical purposes, but not exactly 90 degrees.

[0010] Terms such as “optimal,” “optimize,” “minimum,” “minimize,” “maximum,” and “maximize” may not have specific values ​​associated with them, but where such terms are used herein, it is intended that those skilled in the art will understand that such terms include affecting values, parameters, metrics, etc., in a beneficial direction consistent with the whole of this disclosure. For example, describing a value as “minimum” does not require that the value actually equal a theoretical minimum (e.g., zero), but should be understood in a practical sense that the corresponding goal will move the value in a beneficial direction toward the theoretical minimum.

[0011] context In the context of hard disk drives (HDDs), operational vibration is a major cause of track misalignment (TMR). It should be noted that the main causes of operational vibration are (a) acoustic excitation caused by air pressure fluctuations from the cooling fan, and (b) structurally transmitted external vibrations. The operational vibration problem of customer boxes due to the large noise generated by the cooling fan subsystem within the customer box is considered a significant issue, for example, with regard to head positioning of helium-sealed HDDs. The coil torsion mode of the VCM assembly in a voice coil motor (VCM) actuator is the main cause of the position error signal (PES) in a customer box vibration environment. In a typical 3.5-inch HDD, the second coil torsion mode, with its natural frequency of 6-7 kHz (kilohertz), has the greatest response gain to external excitation caused by fan noise. Therefore, suppressing the gain of the second coil torsion mode is an ongoing challenge in the dynamic design of VCM actuators.

[0012] One known technique for managing the structural dynamics of a VCM actuator involves the use of arm dampers, which are mechanical means to suppress the actuator's response gain. For example, a constraining layer damper typically consists of a viscoelastic material and a thin metal plate and is mounted on the surface of each arm. However, the effect of arm dampers on coil torsional modes is limited because coil torsional modes involve deformation of the coil and pivot bearing as well as the arms. Another known technique for this problem involves the use of adaptive filters, which are means in servo control systems. In noisy customer environments, peak filters are typically added adaptively to the servo controller to suppress spikes in the frequency spectrum of the PES.

[0013] Figure 2 is a perspective view showing a voice coil motor assembly according to an embodiment. The voice coil motor (VCM) assembly 200 (simply "VCM assembly 200") comprises a plurality of arms 202 (see also, e.g., arm 132 in Figure 1), a carriage 204 (see also, e.g., carriage 134 in Figure 1), and a voice coil assembly (VCA) 206. The VCA 206 includes an armature 206a (see also, e.g., armature 136 in Figure 1) attached to the carriage 204 and housing a voice coil 207 (see also, e.g., voice coil 140 in Figure 1), and the VCM further comprises a stator (not shown here, see, e.g., stator 144 in Figure 1) containing a voice coil magnet. As illustrated, according to the embodiment, the VCA 206 of the VCM assembly 200 further comprises a coil reinforcement 208 positioned inside the structure of the voice coil 207 and typically used to add rigidity to the voice coil 207. The VCA 206 is configured to move the arm 202 and the attached head gimbal assembly (HGA) (not shown here, see, e.g., HGA 110 in Figure 1) to access the corresponding portion of the disk stack (see, e.g., recording medium 120 in Figure 1). These components (except the stator 144) are collectively mounted on a pivot shaft (not shown here, see, e.g., pivot shaft 148 in Figure 1) via a pivot bearing assembly (not shown here, see, e.g., pivot bearing assembly 152 in Figure 1). Acoustic excitations applied to the HDD enclosure surface (e.g., base and / or cover) are transmitted through the pivot shaft to the pivot bearings and VCA 206, ultimately displacing the read-write head. Such displacement of the read-write head can be represented by a transfer function diagram / plot. Therefore, acoustic drive vibrations of the HDD in the customer box environment must be addressed.

[0014] Figure 3A is a perspective view showing the structural mechanics of a voice coil motor assembly. The coil torsion modes are briefly described in a three-body model. Thus, the voice coil motor (VCM) assembly 300 (simply "VCM assembly 300") is characterized by a carriage 304 (see also carriage 134, e.g., in Figure 1), to which one or more arms 302 (see also arm 132, e.g., in Figure 1) and a voice coil assembly (VCA) 306 are coupled. The VCA 306 is mounted on the carriage 304 and includes a coil support armature 306a (see also arm 136, e.g., in Figure 1) that houses a voice coil 307 (see also voice coil 140, e.g., in Figure 1), and the VCM further comprises a stator (not shown here, see, e.g., stator 144, in Figure 1) containing a voice coil magnet. The VCM is configured to rotate around the z-axis ("rotation axis") to move the arm 302 and the attached head gimbal assembly (not shown here, see, e.g., HGA110 in Figure 1) to access the corresponding portion of the disk stack (see, e.g., recording medium 120 in Figure 1). These components (except the stator 144) are collectively mounted on a pivot shaft (not shown here, see, e.g., pivot shaft 148 in Figure 1) via a pivot bearing assembly (not shown here, see, e.g., pivot bearing assembly 152 in Figure 1). Here again, acoustic excitation applied to the HDD housing surface (e.g., base and / or cover) is transmitted via the pivot shaft to the pivot bearing and VCM assembly 300, ultimately displacing the read-write head.

[0015] Figure 3A further shows the x-axis ("coil torsion axis"), and the structural mechanics torsion mode of VCA306 is centered on this coil torsion axis. Here, the mechanics of the torsion mode of VCA306 is shown in a simplified form by arrow 310. Furthermore, the arm (sway) mode is shown in a simplified form by arrow 311.

[0016] The coil torsion modes are briefly described by the motion of three components: (i) the VCA 306, (ii) the carriage 304 (including the pivot bearing), and (iii) the arm 302. In the first coil torsion mode, the carriage 304, VCA 306, and arm 302 are tilted to the same side / direction (e.g., clockwise). In the second coil torsion mode, the carriage 304 and arm 302 are tilted to the same side / direction (e.g., counterclockwise), but the VCA 306 is tilted to the opposite side / direction (e.g., clockwise). In the third coil torsion mode, the VCA 306 and arm 302 are tilted to the same side / direction (e.g., clockwise), but the carriage 304 is tilted to the opposite side / direction (e.g., counterclockwise). Figure 3B is a diagram showing the second coil torsion mode of the VCM assembly in Figure 3A. This figure shows the carriage 304 and arm 302 tilting counterclockwise while the VCA 306 tilts clockwise. Thus, the second coil torsion mode consists of a torsion mode of the coil assembly (e.g., VCA 306), a tilting motion of the carriage portion (e.g., carriage 304) as a rigid body, and a swing mode of the arm (e.g., arm 302), the former two having lower frequencies, typically 4–6 kHz lower than the swing mode of the arm.

[0017] Low-density voice coil To reiterate, the operational vibration problem of the customer box due to the significant noise generated by the cooling fan subsystem within the customer box is considered a major challenge for head positioning within the HDD. The coil torsion mode of the VCM assembly of the VCM actuator is the main factor in PES in the customer box vibration environment, and in a typical 3.5-inch HDD, the second coil torsion mode (with an intrinsic frequency of 6-7 kHz) has the greatest response gain to external excitations caused by fan noise. According to the embodiment, the technical objective is frequency matching between the torsion mode and the arm (sway) mode of the coil section (e.g., VCA206, 306 in Figures 2-3B). As mentioned above, the second coil torsion mode is a combination of three modes and therefore has a lower frequency than the highest frequency component (i.e., the arm mode). Since the arm mode frequency is relatively high (due to, for example, the shape of the arm and the weight of the suspension attached to the end of the arm), according to the embodiment, the objective is to increase the frequency of the coil section's torsion mode to bring it closer to the frequency of the arm mode.

[0018] Figure 4 is a perspective view showing a VCM assembly according to an embodiment. Figure 4 shows a voice coil motor (VCM) assembly 400 (simply "VCM assembly 400") configured to be installed and operated within an HDD having disk media mounted on a spindle (not shown here, see, for example, recording medium 120 in Figure 1), such as a conventional hard disk drive (HDD) 100 (Figure 1); a head slider housing a read-write transducer (not shown here, see, for example, a slider 110b including a magnetic read-write head 110a in Figure 1) configured to read from and write to disk media among a plurality of disk media; and a rotary actuator assembly shown herein, i.e., the VCM assembly 400 configured to move the head slider around a pivot (see also a pivot shaft 148 having an interposed pivot bearing assembly 152 in Figure 1) to access portions of the disk media.

[0019] According to one embodiment, the VCM assembly 400 comprises a plurality of arms 402 (see also arm 132, e.g., in Figure 1), a carriage 404 (see also carriage 134, e.g., in Figure 1), and a voice coil assembly (VCA) 406. The VCA 406 includes an armature 406a (see also armature 136, e.g., in Figure 1) that is mounted on the carriage 404 and houses a voice coil 407 (see also voice coil 140, e.g., in Figure 1) containing a coil of wire having a first density. The VCM further comprises a stator (not shown here, see, e.g., stator 144, in Figure 1) containing a voice coil magnet. As shown, the VCA 406 of the VCM assembly 400 further comprises a coil reinforcement 408 positioned inside the structure of the voice coil 407, and according to one or more embodiments, the reinforcement 408 comprises a material having a second density greater than the first density. Therefore, the wires constituting the voice coil 407 are made of a relatively low-density material, while the reinforcing material 408 is made of a relatively high-density material. Thus, the voice coil 407 is configured to increase the torsional mode frequency of the VCA 406 compared to the torsional mode frequencies of other conventional voice coils (e.g., copper wire) and assemblies containing wires with a density higher than the first density.

[0020] According to one or more embodiments, the wire of the voice coil 407 is made of a material from the group consisting of copper-clad aluminum wire (CCAW) and aluminum wire. Typically, the natural frequency of the arm mode is significantly higher than the torsion mode frequency of the voice coil assembly, and the second coil torsion mode has the greatest contribution in the PES spectrum under noisy customer box conditions. Since the CCAW (or aluminum wire) voice coil 407 is lighter than a conventional copper coil, the torsion mode frequency of the voice coil 407 (and similarly the VCA 406) having a CCAW (or aluminum wire) coil is higher than that of a conventional copper coil. Therefore, in scenarios where the second torsion mode frequency of the VCA 406 is substantially close to the arm frequency, the response gain of the second coil torsion mode to external excitation is small.

[0021] High-density coil reinforcing material The implementation of the low-density voice coil 407 can provide the aforementioned advantages as described, but such a configuration may have an undesirable impact on the center of mass of the VCA406, such as reducing the HDD performance under vibration conditions. Therefore, according to one or more embodiments, in combination with the implementation of the low-density ("first density") voice coil 407, a high-density ("second density") coil reinforcing material 408 is implemented. Therefore, the reinforcing material 408 with a higher density is configured to increase the mass of the VCM assembly and compensate for the wire of the voice coil 407 with a lower density in the context that the center of mass of the VCM assembly is centered on its rotation axis, as shown in FIG. 4. According to one or more embodiments, the reinforcing material is composed of a material from the group consisting of stainless steel, copper or copper alloy, and zinc-aluminum alloy. As a non-limiting example, austenitic stainless steels such as SUS304 and SUS305 can be utilized, and SUS305 has better stability against machining than SUS304. The role of the reinforcing material 408 in the described embodiments is generally its mass rather than its rigidity. Therefore, the reinforcing material 408 may be composed of other materials such as naval brass or plastic-metal composite materials as non-limiting examples. Since the low-density voice coil 407 and the high-density reinforcing material 408 are assembled by adhesion, preferably, the coefficient of thermal expansion (CTE) of the reinforcing material 408 is substantially close to or equivalent to the CTE of the wire of the voice coil 407 to avoid cracking of the adhesive.

[0022] As shown in FIG. 4, according to one or more embodiments, the high-density reinforcing member 408 is positioned radially inside the coil of the wire of the voice coil 407 such that the center of mass of the reinforcing member 408 in the direction opposite to the axis of the torsional movement is substantially close to the axis of the torsional movement. Since the mass of the high-density reinforcing member 408 is positioned close to the axis of the torsional movement, the high-density reinforcing member 408 has a minimal impact on the coil torsional mode frequency while effectively compensating the center of mass of the VCM actuator assembly.

[0023] Method of manufacturing a voice coil motor assembly FIG. 5 is a flowchart showing a method of manufacturing a voice coil motor assembly according to an embodiment. The voice coil motor assembly (VCMA) assembled, manufactured, and produced according to the method of FIG. 5 is designed, configured, and intended for implementation in a hard disk drive (HDD) (e.g., see FIG. 1). However, other implementation contexts are not excluded.

[0024] In block 502, a voice coil including a coil of wire is formed, the wire having a first density and configured to increase the second coil torsional mode frequency of the voice coil motor assembly to a second coil torsional mode frequency of a voice coil motor assembly comprising a voice coil including a wire having a density higher than the first density. For example, the low-density voice coil 407 (FIG. 4) is formed including a coil of CCAW or aluminum wire, the low-density wire having a first density and configured to increase the second coil torsional mode frequency of the VCMA to a second coil torsional mode frequency of a VCMA comprising a voice coil including a wire having a density higher than the first density, such as a copper wire coil.

[0025] In block 504, a reinforcing material is placed inside the wire coil, and the reinforcing material comprises a material having a second density greater than a first density, and is configured to substantially balance the center of mass of the voice coil motor assembly around its axis of rotation. For example, a high-density reinforcing material 408 (Figure 4) is placed inside the wire coil of the voice coil 407, and the reinforcing material 408 comprises steel, copper, or zinc, and is configured to substantially balance the center of mass of the VCMA around its axis of rotation, for example, around the pivot shaft 148 (Figure 1) and the pivot bearing assembly 152 (Figure 1).

[0026] For example, the implementation of a voice coil motor actuator with a CCAW coil and stainless steel reinforcement can achieve a small response gain for the second coil torsion mode of a VCMA while minimizing any impact on the actuator's performance. When the torsion mode frequency and arm mode frequency substantially coincide, the tilt motion of the body in the second coil torsion mode becomes almost zero. In this case, the center of mass and principal axes of inertia are hardly affected by the combination of low-density voice coil and high-density coil reinforcement, so this mode is not excited by external vibrations via the pivot shaft. When observing and analyzing the customer box vibration state with respect to the position error signal (PES), the large peak in the PES spectrum due to the second coil torsion mode in conventional methods (e.g., copper coil with aluminum reinforcement) is largely eliminated, if not completely, and the PES power is reduced to about half of that in conventional methods. From the above, it is considered that the operating vibration performance of the HDD will be improved under noisy customer box conditions. Furthermore, since the external shape and mechanics of the actuator remain almost the same as in conventional methods, the impact on the design and other performance of other mechanical parts is minimized.

[0027] Illustrative physical explanation of the operating context The embodiments may be used in the context of digital data storage devices (DSDs), such as hard disk drives (HDDs). Accordingly, according to the embodiments, a plan view showing a conventional HDD 100 is shown in Figure 1, which helps to illustrate how conventional HDDs and similar multi-actuator HDDs typically operate.

[0028] Figure 1 shows the functional arrangement of the components of the HDD 100, including a slider 110b containing a magnetic read-write head 110a. Collectively, the slider 110b and the head 110a may be referred to as the head slider. The HDD 100 includes the head slider and at least one head gimbal assembly (HGA) 110, which typically includes a lead suspension 110c attached to the head slider 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, though usually multiple recording media 120, rotatably mounted on a spindle 124, and a drive motor (not shown) attached to the spindle 124 for rotating the media 120. The read-write head 110a, which may also be referred to as a transducer, includes a write element and a read element for writing and reading information stored in the media 120 of the HDD 100, respectively. The media 120 or more disk media can be secured to the spindle 124 by disk clamps 128.

[0029] The HDD 100 further includes an arm 132 attached to the HGA 110, a carriage 134 to which the arm 132 is attached, a voice coil motor (VCM) including an armature 136 attached to the carriage 134 and housing a voice coil 140, and a stator 144 including a voice coil magnet (not shown). The VCM is configured to move the arm 132 and the HGA 110 to access portions of the media 120. These components (except the stator 144) are collectively mounted on a pivot shaft 148 via a pivot bearing assembly 152. In the case of an HDD with 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 interconnected arms that gives the carriage a comb-like appearance.

[0030] An assembly comprising a head gimbal assembly (e.g., HGA110) including a flexure coupled to a head slider, an actuator arm (e.g., arm 132) and / or a load beam coupled to the flexure, and an actuator (e.g., VCM) coupled to the actuator arm, can be collectively referred to as a head stack assembly (HSA). However, an HSA may include more or fewer components than those described. For example, an HSA may refer to an assembly that further includes electrical interconnection components. Generally, an HSA is an assembly configured to move the head slider to access a portion of the medium 120 for read and write operations.

[0031] Referring further to Figure 1, electrical signals, including write signals to and read signals from head 110a (e.g., current to the voice coil 140 of the VCM), are transmitted by a Flexible Cable Assembly (FCA) 156 (or "Flex Cable," or "Flexible Printed Circuit (FPC)"). The interconnection between the Flex Cable 156 and head 110a may include an Arm-Electronics (AE) module 160, which may have an onboard preamplifier for read signals, as well as other read and write channel electronic components. The AE module 160 may be mounted on the carriage 134 as shown. In some configurations, the Flex Cable 156 may be coupled to an electrical connector block 164 that provides electrical communication through an electrical feedthrough provided by the HDD housing 168. The HDD housing 168 (or "enclosure base" or "base plate" or simply "base"), together with the HDD cover (which is removed here to show the internal components), provides a semi-enclosed (or, depending on the configuration, hermetically sealed) enclosure that protects the information storage components of the HDD 100.

[0032] Other electronic components, including a disk controller with a Digital-Signal Processor (DSP) and servo electronics, provide electrical signals to the drive motor, the voice coil 140 of the VCM, and the head 110a of the HGA 110. The electrical signals provided to the drive motor enable the drive motor to provide torque to the spindle 124 as it rotates, and the torque is then transmitted to the medium 120 fixed to the spindle 124. As a result, the medium 120 rotates in direction 172. The rotating medium 120 creates an air cushion that acts as an air bearing on which the air-bearing surface (ABS) of the slider 110b rests, so that the slider 110b floats above the surface of the medium 120 without contacting the thin magnetic recording layer on which the information is recorded. Similarly, as a non-limiting example, in an HDD using a gas lighter than air, such as helium, the rotating medium 120 creates a gas cushion that acts as a gas bearing or fluid bearing on which the slider 110b rests.

[0033] The electrical signals supplied to the voice coil 140 of the VCM enable the head 110a of the HGA 110 to access track 176 on which information is recorded. Thus, the armature 136 of the VCM swing through arc 180 enables the head 110a of the HGA 110 to access various tracks on the medium 120. The information is stored on the medium 120 in multiple radially nested tracks arranged in sectors on the medium 120, such as sector 184. Correspondingly, each track consists of multiple sectorized track portions (or "track sectors"), such as sectorized track portion 188. Each sectorized track portion 188 may include a header containing the recorded information, error correction code information, and a servo burst signal pattern, such as an ABCD servo burst signal pattern, which is information identifying track 176. When accessing track 176, the reading element of the head 110a of the HGA110 reads a servo burst signal pattern, which provides a position error signal (PES) to the servo electronics, which in turn controls an electrical signal supplied to the voice coil 140 of the VCM, thereby enabling the head 110a to follow track 176. Once track 176 is found and a specific sectored track portion 188 is identified, the head 110a reads information from or writes information to track 176 in response to instructions received by the disk controller from an external agent, such as a microprocessor of a computer system.

[0034] The electronic architecture of an HDD includes numerous electronic components that perform their respective functions for the operation of the HDD, such as the Hard Disk Controller (HDC), interface controller, ARM electronic module, data channel, motor driver, servo processor, and buffer memory. Two or more of these components may be combined on a single integrated circuit board, referred to as a "system on a chip" (SOC). Some, if not all, of these electronic components are typically located on a printed circuit board coupled to the bottom side of the HDD, such as the HDD housing 168.

[0035] References to hard disk drives in this specification, such as HDD100 shown and described with reference to Figure 1, may encompass information storage devices sometimes referred to as “hybrid drives.” A hybrid drive generally refers to a storage device that has the functions of both a conventional HDD (see, for example, HDD100) and a solid-state storage device (SSD) that uses non-volatile memory such as electrically erasable and programmable flash or other solid-state (e.g., integrated circuit) memory. Because the operation, management, and control of different types of storage media are typically different, the solid-state portion of a hybrid drive may include its own corresponding controller function, and the controller function may be integrated with the HDD function into a single controller. A hybrid drive may be designed and configured to operate and utilize the solid-state portion in several ways, such as using solid-state memory as cache memory to store frequently accessed data, or to store I / O (Input / Output) aggregated data, as an example not limited to this. Furthermore, the hybrid drive may be essentially designed and configured as two storage devices in a single enclosure, namely a conventional HDD and an SSD, with one or more interfaces for host connectivity.

[0036] Extensions and replacements In the foregoing description, embodiments of the present invention have been described with reference to numerous specific details that may differ depending on the implementation. Accordingly, various modifications and changes may be made without departing from the broader spirit and scope of the embodiments. Accordingly, what constitutes the present invention, and what the applicants intend to constitute the present invention, is a set of claims of a particular form derived from this application, and such claims, including any subsequent amendments, are derived from a particular form. The definitions expressly set forth herein for terms included in such claims shall govern the meaning of terms as used in the claims. Accordingly, no limitations, elements, characteristics, features, advantages or attributes not expressly set forth in the claims shall in any way limit such claims. Accordingly, this specification and the drawings should be considered illustrative and not restrictive.

[0037] In this description, certain process steps may be described in a specific order, and certain steps may be identified using alphabetical and alphanumeric codes. Unless otherwise specified herein, embodiments are not necessarily limited to any particular order in which such steps are performed. In particular, the codes are used merely for the convenience of identifying steps and are not intended to specify or require a particular order in which such steps are performed.

Claims

1. A data storage device, Multiple disk media rotatably mounted on a spindle, A head slider equipped with a read-write head configured to write to and read from one of the aforementioned multiple disk media, The system comprises a rotary actuator configured to move the head slider around a pivot to access a portion of the disk medium via operation by a voice coil motor (VCM) assembly, the VCM assembly is A voice coil comprising a coil of wire having a first density, A data storage device comprising: a reinforcing material disposed inside the coil of the wire and having a second density greater than the first density;

2. The data storage device according to claim 1, wherein the voice coil is configured to increase the torsional mode frequency of the VCM assembly, which includes a wire having a density higher than the first density.

3. The VCM assembly further includes a plurality of arms extending from the carriage, The data storage device according to claim 2, wherein the torsional mode is a second coil torsional mode of the VCM assembly, corresponding to a structural mechanics mode in which the carriage and the plurality of arms tilt in one direction and the VCM assembly tilts in the opposite direction.

4. The data storage device according to claim 3, wherein the voice coil is configured to bring the second torsional mode frequency of the VCM assembly closer to the second torsional mode frequencies of the plurality of arms.

5. The data storage device according to claim 1, wherein the reinforcing material having a higher second density is configured to increase the mass of the VCM assembly with respect to the center of mass of the VCM assembly, which is centered on the rotation axis of the VCM assembly, thereby compensating for the wire having a lower first density.

6. The data storage device according to claim 5, wherein the reinforcing member is positioned radially inward of the wire coil such that the center of mass of the reinforcing member in the direction opposite to the axis of torsional motion is substantially close to the axis of torsional motion.

7. The wire is made of a material from the group consisting of (i) copper-clad aluminum and (ii) aluminum, The data storage device according to claim 1, wherein the reinforcing material is made of a material from the group consisting of (i) stainless steel, (ii) copper or copper alloy, and (iii) zinc-aluminum alloy.

8. A voice coil motor (VCM) assembly, A voice coil comprising a coil of wire having a first density, A voice coil motor (VCM) assembly comprising: a reinforcing material disposed inside the coil of the wire and having a second density greater than the first density;

9. The VCM assembly according to claim 8, wherein the voice coil is configured to increase the torsional mode frequency of the VCM assembly, with respect to the torsional mode frequency of the VCM assembly, which includes a voice coil including a wire having a density higher than the first density.

10. It further includes multiple arms extending from the carriage, The VCM assembly according to claim 9, wherein the torsional mode is a second coil torsional mode of the VCM assembly, corresponding to a structural mechanics mode in which the carriage and the plurality of arms are tilted in one direction and the voice coil is tilted in the opposite direction.

11. The VCM assembly according to claim 10, wherein the voice coil is configured to bring the second torsional mode frequency of the VCM assembly closer to the second torsional mode frequencies of the plurality of arms.

12. The VCM assembly according to claim 8, wherein the reinforcing material having a higher second density is configured to increase the mass of the VCM assembly with respect to the center of mass of the VCM assembly, which is centered on the rotation axis of the VCM assembly, thereby compensating for the wire having a lower first density.

13. The VCM assembly according to claim 12, wherein the reinforcing member is positioned radially inward of the coil of wire such that the center of mass of the reinforcing member in the direction opposite to the axis of torsional motion is substantially close to the axis of torsional motion.

14. The VCM assembly according to claim 8, wherein the wire is made of a material from the group consisting of (i) copper-clad aluminum and (ii) aluminum.

15. The VCM assembly according to claim 14, wherein the reinforcing material is composed of a material from the group consisting of (i) stainless steel, (ii) copper or copper alloy, and (iii) zinc-aluminum alloy.

16. A hard disk drive comprising the VCM assembly described in claim 15.

17. A method for manufacturing a voice coil motor assembly, To form a voice coil including a wire coil, wherein the wire has a first density and is configured to increase the second coil torsion mode frequency of the voice coil motor assembly relative to the second coil torsion mode frequency of a voice coil motor assembly including a voice coil including a wire having a density higher than the first density, A method comprising arranging a reinforcing material inside the coil of the wire, wherein the reinforcing material comprises a material having a second density greater than the first density, and is configured to substantially equilibrium the center of mass of the voice coil motor assembly around its axis of rotation.

18. Forming the voice coil includes forming it using wire material from the group consisting of (i) copper-clad aluminum and (ii) aluminum, The method according to claim 17, wherein the arrangement of the reinforcing material includes arranging a reinforcing material composed of a material from the group consisting of (i) stainless steel, (ii) copper or copper alloy, and (iii) zinc-aluminum alloy.

19. It is a hard disk drive (HDD), Multiple disk media rotatably mounted on a spindle, Means for reading from one of the aforementioned disk media and writing to the disk media, The system comprises a rotary actuator configured to move means for reading and writing to the access portion of the disk medium via operation by a voice coil motor (VCM) assembly, wherein the VCM assembly A voice coil including a wire coil, A reinforcing material is placed inside the coil of the aforementioned wire, Multiple arms extending from the carriage, A hard disk drive (HDD) comprising means for increasing a second coil torsion mode frequency of the VCM assembly, corresponding to a structural mechanics mode in which the carriage and the plurality of arms are tilted in one direction and the voice coil is tilted in the opposite direction, relative to a second coil torsion mode frequency of a VCM assembly that does not otherwise include such means.

20. The means for increasing the second coil torsion mode frequency of the VCM assembly is configured to bring the second torsion mode frequency of the VCM assembly closer to the second torsion mode frequency of the plurality of arms, The HDD according to claim 19, wherein the VCM assembly further includes means for substantially balancing the center of mass of the VCM assembly around its axis of rotation.

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