Shortening the bearing span by increasing the coil thickness to improve the structural dynamics of actuators in hard disk drives.

Abstract

Improve non-repetitive runout (NRRO) associated with the system's structural dynamics and operating vibrations. [Solution] A data storage device such as a hard disk drive (HDD) includes a rotary pivot bearing assembly of a rotary actuator configured with a bearing span smaller than the maximum available bearing span, thereby reducing the rotary pivot tilt (PT) gain of the corresponding acoustic transfer function relative to the rotational pivot tilt (PT) gain of the original acoustic transfer function corresponding to the maximum available bearing span. To counteract the resulting decrease in coil torsion and rotational pivot tilt frequency, the voice coil is thickened vertically to increase the coil torsion (CT) frequency and rotational pivot tilt frequency, bringing them closer to their values ​​in the original acoustic transfer function. Combining a relatively short bearing span with a relatively thick voice coil ensures and improves performance by maintaining relatively high CT and PT frequencies while guaranteeing a relatively low PT gain.

Description

Technical Field

[0001] Embodiments of the present invention generally relate to data storage devices such as hard disk drives, and more particularly to an approach for improving the structural dynamics of an actuator assembly within a hard disk drive.

Background Art

[0002] A hard disk drive (HDD) is a non - volatile storage device that stores digitally encoded data on one or more circular disks having a magnetic surface, housed within a protective enclosure. 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 transducer (or read - write “head”) 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 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 electric currents. The current in the coil of the write head generates a local magnetic field across the gap between the head and the magnetic disk, and this magnetic field then magnetizes a small area on the recording medium.

[0003] An HDD typically includes at least one head gimbal assembly (HGA) which contains a slider and suspension housing the read-write heads. Each slider is mounted to the free end of the suspension, which is then cantilevered from a rigid arm of an actuator. Several actuator arms may 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 an actuator arm, and its free end mounts a flexure that carries the slider and its read-write heads.

[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 one form, this goal manifests as increasing the number of disks and read-write heads in a given HDD. In modern HDDs, operational vibration (also called "customer box vibration") is one of the most important factors in track misalignment (TMR), which generally refers to the variation in the deviation of the track-following / servo head from its intended position, i.e., the deviation of the read-write head from the center of the data track. 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 approach described in this section is a possible approach, but not necessarily a previously conceived or pursued method. Therefore, unless otherwise indicated, none of the approaches described in this section should be assumed to be eligible as prior art simply by their inclusion in this section. [Brief explanation of the drawing]

[0006] Embodiments are shown in the accompanying drawings as examples, not as limitations, and similar reference numerals refer to similar elements. [Figure 1] This is a plan view showing a hard disk drive (HDD) according to one embodiment. [Figure 2A] This is a cross-sectional side view showing the HDD rotational pivot bearing assembly. [Figure 2B] This is a side view showing the HDD voice coil actuator assembly. [Figure 2C] Figure 2B is a top view showing the HDD voice coil actuator assembly. [Figure 3] This is a cross-sectional side view showing a shortened span HDD rotational pivot bearing assembly according to one embodiment. [Figure 4A] This figure shows the acoustic transfer function of the head stack assembly (HSA) corresponding to the HDD rotational pivot bearing assembly in Figure 2A. [Figure 4B] This figure shows the HSA acoustic transfer function corresponding to the shortened span HDD rotational pivot bearing assembly shown in Figure 3, according to one embodiment. [Figure 5A] This is a side view showing an increased-thickness voice coil of an HDD voice coil actuator assembly according to one embodiment. [Figure 5B] This is a top view showing the increased-thickness voice coil of the HDD voice coil actuator assembly of Figure 5A, according to one embodiment. [Figure 6A] Figures 2B and 2C show the HSA acoustic transfer function corresponding to the HDD voice coil actuator assembly. [Figure 6B] This figure shows the HSA acoustic transfer function corresponding to the increased-thickness voice coil in Figures 5A and 5B, according to one embodiment. [Figure 7A] This figure shows the HSA frequency response function corresponding to the operating vibration of the HDD rotating pivot bearing assembly in Figure 2A and the HDD voice coil actuator assembly in Figures 2B to 2C. [Figure 7B] This figure shows the shortened span HDD rotational pivot bearing assembly shown in Figure 3 and the HSA frequency response function corresponding to the operating vibration of the increased thickness voice coil shown in Figures 5A to 5B, according to one embodiment. [Modes for carrying out the invention]

[0007] Generally, approaches to improving the structural dynamics of actuator systems within hard disk drives are described. The following specification 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 implemented without these specific details. In other cases, well-known structures and devices may be represented 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, examples of such phrases do not necessarily all refer to the same embodiment.

[0009] While the term "substantially" is understood to describe features such as being largely or nearly structured, configured, or dimensioned, manufacturing tolerances and other factors can result in situations where the structure, configuration, dimensions, etc., are not always or not precisely described. For example, describing a structure as "substantially vertical" assigns its simple meaning to the term, as the structure may be vertical for all practical purposes, but not exactly 90 degrees throughout.

[0010] Terms such as “optimal,” “optimize,” “minimal,” “minimize,” “maximal,” and “maximize” may not necessarily have specific values ​​associated with them. However, where such terms are used herein, it is intended that those skilled in the art will understand that they include influencing values, parameters, metrics, etc., in a beneficial direction consistent with the whole of this disclosure. For example, describing a value as “minimal” does not require the value to actually be equal to 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 vibrations are a major cause of track misalignment (TMR). It should be noted that the main causes of operational vibrations are (a) acoustic excitations caused by air pressure fluctuations from the cooling fan, and (b) structurally transmitted external vibrations. Furthermore, structurally transmitted vibrations are dominant at low frequencies (0kHz to 3kHz), while acoustic vibrations are dominant at high frequencies (3kHz to 10kHz). The HDD's response to acoustic excitations is characterized by its acoustic transfer function (or acoustic TF), which is defined as the off-track displacement of the head due to a unit sound pressure excitation applied to the HDD enclosure. Acoustic excitations applied to the HDD enclosure surface are transmitted via the rotating pivot shaft to the rotating pivot bearing and actuator body, ultimately displacing the head. For example, it is expected that the acoustic TF and non-repetitive runout (NRRO) will worsen with advancements in base thickness, arm number, and arm thinning. The final customer box NRRO can be calculated as the product of the acoustic TF, the customer box sound pressure profile, and the error transfer function (ETF) of the servo controller. The acoustic TF and predicted customer box NRRO for modern HDDs show a large peak in the 6kHz–7kHz range due to the rotational pivot tilt (PT) mode. This mode shape includes the rotational pivot, coil, and tilt / torsion motion of the actuator arm.

[0012] Figure 2A is a side cross-sectional view showing an HDD rotating pivot bearing assembly. The rotating pivot bearing assembly 200 comprises a rotating pivot shaft 202 and a bearing assembly 204 fixed around the rotating pivot shaft 202. The bearing assembly 204 comprises an upper bearing 204a and a lower bearing 204b, both of which include corresponding outer races 204a-1 and 204b-1 mounted on an outer bearing sleeve 205. The distance between the upper bearing 204a and the lower bearing 204b is called the bearing span, which is typically measured between the position (e.g., center) of the balls in the upper bearing 204a and the same position (e.g., center) of the balls in the lower bearing 204b, as shown in the figure. Here, for illustrative purposes, in the context of a disk HDD with a 1-inch form factor and a 3.5-inch diameter, the bearing span of the bearing assembly 204 is shown as 14.7 mm (millimeters). This bearing span configuration is considered to be the maximum available bearing span based on the vertical distance between the HDD base (not shown here, see, for example, the HDD housing 168 in Figure 1) and the corresponding cover (not shown here, see, for example, the cover in the description of Figure 1).

[0013] Figure 2B is a side view showing the HDD voice coil actuator assembly, and Figure 2C is a top view showing the HDD voice coil actuator assembly of Figure 2B. The voice coil actuator assembly 210 (simply "VCA210") comprises a plurality of arms 212 (see also arm 132, e.g., in Figure 1), a carriage 214 (see also carriage 134, e.g., in Figure 1), and a voice coil assembly including an armature 216 (see also armature 136, e.g., in Figure 1) mounted on the carriage 214 and housing a voice coil 217 (see also voice coil 140, e.g., in Figure 1). The voice coil motor (VCM) further includes a stator (not shown here, see, e.g., stator 144, in Figure 1) including a voice coil magnet. The VCM is configured to move the arms 212 and a head gimbal assembly (HGA) (not shown here) mounted thereon. (For example, the head gimbal assembly (see HGA110 in Figure 1) can be used to access the corresponding portion of the disk stack (for example, see recording medium 120 in Figure 1).) These components (except the stator 144) are mounted together on the rotary pivot shaft 202 via the rotary pivot bearing assembly 204. Herein, for illustrative purposes, in the context of a disk HDD with a 1-inch form factor and a 3.5-inch diameter, the thickness of the voice coil 217 is shown as 3.2 mm (millimeters) (Figure 2B), and the width of the voice coil 217 is shown as 3.9 mm (Figure 2C).

[0014] As described above, acoustic excitations acting on the HDD enclosure surface (e.g., base and / or cover) are transmitted via a rotating pivot shaft, such as the rotating pivot shaft 202, to the rotating pivot bearing, such as the bearing assembly 204, and to the carriage 214, ultimately displacing the read-write head. Such displacement of the read-write head can be represented by an acoustic TF diagram / plot (see, e.g., Figures 4A-4B, 6A-7B) or other similar frequency response function (FRF) diagram / plot. Therefore, acoustic drive vibrations of the HDD must be addressed in the customer box environment.

[0015] Shortened span HDD rotary pivot bearing assembly According to the embodiment, the goal is to reduce the gain of the rotational pivot tilt (PT) mode (of structural dynamics) in the acoustic TF while maintaining or increasing the mode frequency. Conventionally, it has been standard practice to maximize the bearing span of the actuator rotational pivot in order to maximize the torsional stiffness of the rotational pivot and therefore also maximize the coil torsion (CT) and PT mode frequencies. Furthermore, previous approaches to reducing the PT mode gain in the acoustic TF have included optimizing the profile shape / geometric shape of the actuator arm. However, these changes to the arm profile may not be sufficient to meet the TMR target of HDD platforms with an increased number of recording disks. According to the embodiment, a suitable combination of (a) reducing the bearing span (from its maximum value) and (b) increasing the coil thickness is provided to improve the overall dynamics of the actuator, particularly the acoustic transfer function response.

[0016] Figure 3 is a side cross-sectional view showing a shortened span HDD rotary pivot bearing assembly according to one or more embodiments. Figure 3 shows a rotary pivot bearing assembly configured to be installed in and operate in a conventional hard disk drive (HDD) (e.g., HDD 100 (Figure 1)), for example, HDD 100 (Figure 1) comprising a disk medium mounted on a spindle (e.g., recording medium 120 in Figure 1), a head slider (e.g., slider 110b including a magnetic read-write head 110a in Figure 1) that houses a read-write transducer configured to read and write to the disk medium, and an actuator assembly (e.g., voice coil 140 of the VCM in Figure 1) configured to move the head slider around a rotary pivot (e.g., a rotary pivot shaft 148 with a rotary pivot bearing assembly 152 in Figure 1) to access a portion of the disk medium. These HDD components are housed in an enclosure including a base (e.g., HDD housing 168 in Figure 1).

[0017] The rotary pivot bearing assembly 300 includes a rotary pivot shaft 302 and a bearing assembly 304 fixed around the rotary pivot shaft 302. The bearing assembly 304 includes an upper bearing 304a and a lower bearing 304b, both of which include corresponding outer races 304a-1, 304b-1 attached to an outer bearing sleeve 305. The distance between the upper bearing 304a and the lower bearing 304b is called the bearing span, which is typically measured between the position (e.g., the center) of the balls of the upper bearing 304a and the same position (e.g., the center) of the balls of the lower bearing 304b as shown in the figure. Here, for illustrative purposes, in the context of a 1-inch form factor, 3.5-inch diameter disk HDD, the bearing span of the bearing assembly 304 is shown as 10.7 mm. This configuration of the bearing span is considered to be smaller than the maximum available bearing span based on the vertical distance between the HDD base (not shown here, e.g., refer to the HDD housing 168 in FIG. 1) and the corresponding cover (not shown here, e.g., refer to the cover in the description of FIG. 1). Therefore, compared to the rotary pivot bearing assembly 200 that employs the maximum available bearing span, the rotary pivot bearing assembly 300 employs a reduction of approximately 27% in the bearing span.

[0018] Contrary to intuition, analysis shows that shortening the bearing span has advantages in dynamics. Specifically, shortening the bearing span leads to a significant decrease in PT gain in the acoustic TF, and therefore shortening the bearing span allows for a reduction in PT gain. However, as expected, shortening the bearing span causes undesirable decreases in both the CT frequency and the PT frequency. Figure 4A is a diagram showing the head stack assembly (HSA) acoustic transfer function corresponding to the HDD rotational pivot bearing assembly of Figure 2A, and Figure 4B is a diagram showing the HSA acoustic transfer function corresponding to the shortened span HDD rotational pivot bearing assembly of Figure 3, according to one or more embodiments. These acoustic TF diagrams show the (first) PT402 (Figure 4A) corresponding to the (first) acoustic transfer function corresponding to the maximum available bearing span, such as the bearing assembly 200 of Figure 2A, with respect to the (second) PT412 (Figure 4B) corresponding to the (second) acoustic transfer function corresponding to the shortened span bearing span, such as the bearing assembly 300 of Figure 3, according to one embodiment. Therefore, the shortened span bearing assembly 300 facilitates, generates, and enables a non-trivial reduction in PT gain (in this non-limiting embodiment, a reduction of approximately 0.75 nm / Pa, or approximately 37.5%). Generally, for the same input excitation at both ends of the rotating pivot shaft, a stiffer, longer rotating pivot bearing span transmits more acoustic energy to the head than a less stiff, shorter rotating pivot bearing span. Analysis in the context of a 1-inch form factor, 3.5-inch diameter disk HDD with 10 or more disks has shown that bearing spans in the range of 5 mm to 13 mm (5 mm to 13 mm) are suitable for the purposes described above.

[0019] However, as described above, this reduction in PT gain is achieved at the "cost" of a decrease in CT frequency and PT frequency, as indicated by CT frequency reduction 413 and PT frequency reduction 414. For example, generally, when the CT frequency decreases, the CT frequency can approach the phase crossover frequency of the head positioning control system, which can lead to instability of the control system. Furthermore, regarding the PT frequency, although the PT gain decreases as the bearing span shortens, the input sound pressure generally has higher power at low frequencies. Therefore, when the PT frequency decreases, the advantage due to the decrease in PT gain in the acoustic TF is effectively canceled out, thereby moderately improving or even worsening the PT NRRO. Since a rotating pivot bearing with a short span has lower (torsional) rigidity compared to a rotating pivot bearing with a long span, in this scenario, the PT frequency and CT frequency of the rotating pivot with a short span become undesirably low.

[0020] Increased Thickness HDD Voice Coil Assembly Considering that the aforementioned reduction in the rotational pivot bearing span (i.e., from bearing assembly 200 in Figure 2A to bearing assembly 300 in Figure 3) reduces the CT frequency and PT frequency, according to the embodiment, a thicker voice coil is employed to increase the CT frequency and PT frequency. Figure 5A is a side view showing the increased-thickness voice coil of the HDD voice coil actuator assembly, and Figure 5B is a top view showing the increased-thickness voice coil of the HDD voice coil actuator assembly in Figure 5A. Both are according to one or more embodiments. Figures 5A and 5B show a voice coil assembly configured to be installed in and operate in a conventional hard disk drive (HDD), such as HDD 100 (Figure 1), which comprises a disk medium mounted on a spindle (e.g., recording medium 120 in Figure 1), a head slider housing a read-write transducer (e.g., slider 110b including magnetic read-write head 110a in Figure 1) configured to read and write to the disk medium, and an actuator assembly (e.g., voice coil 140 of the VCM in Figure 1) configured to move the head slider around a rotational pivot (e.g., rotational pivot shaft 148 with rotational pivot bearing assembly 152 interposed in Figure 1) to access a portion of the disk medium. These HDD components are housed within an enclosure including a base (e.g., HDD housing 168 in Figure 1).

[0021] The voice coil actuator assembly 500 (simply "VCA500") comprises a plurality of arms 512 (see also arm 132, e.g., in Figure 1), a carriage 514 (see also carriage 134, e.g., in Figure 1), and a voice coil assembly, the voice coil assembly including an armature 516 (see also armature 136, e.g., in Figure 1) mounted on the carriage 514 and housing a voice coil 517 (see also voice coil 140, e.g., in Figure 1). The voice coil motor (VCM) further includes a stator (not shown here, see, e.g., stator 144, in Figure 1) containing a voice coil magnet. The VCM is configured to move the arms 512 and a head gimbal assembly (HGA) (not shown here, see, e.g., HGA110, in Figure 1) mounted thereon to access a corresponding portion of the disk stack (see, e.g., recording medium 120, in Figure 1). These components (excluding the stator 144) are mounted together to the rotary pivot shaft 502 (see also the rotary pivot shaft 302 in Figure 3) via a rotary pivot bearing assembly 504 (see also the bearing assembly 304 in Figure 3). Here, for illustrative purposes, in the context of a disk HDD with a 1-inch form factor and a 3.5-inch diameter, the thickness of the voice coil 517 is shown as 3.8 mm (Figure 5A), and the width of the voice coil 517 is shown as 3.2 mm (Figure 5B). Thus, compared to the VCA210 (Figures 2B-2C), the VCA500 has approximately 19% greater voice coil thickness. Furthermore, in one embodiment, in order to minimize the influence on the inertia of the voice coil 517, it is preferable to combine an increase in coil thickness and a decrease in coil width, reducing the coil width from 3.9 mm for the voice coil 217 (Figures 2B-2C) to 3.2 mm for the voice coil 517 (a reduction of approximately 22%), while keeping the number of turns and coil mass approximately the same / equivalent.

[0022] Figure 6A is a diagram showing the HSA acoustic transfer function corresponding to the HDD voice coil actuator assemblies of Figures 2B-2C according to one or more embodiments, and Figure 6B is a diagram showing the HSA acoustic transfer function corresponding to the increased thickness voice coils of Figures 5A-5B according to one or more embodiments. These acoustic TF diagrams show a (second) PT612 (Figure 6B) corresponding to the (second) acoustic transfer function corresponding to the (second) vertical thickness of the voice coil of a VCA such as the VCA210 of Figures 2B-2C, with respect to a (first) PT602 (Figure 6A) corresponding to the (first) acoustic transfer function corresponding to the (first) vertical thickness of the voice coil of a VCA such as the VCA210 of Figures 2B-2C, with respect to a (second) PT612 (Figure 6B) corresponding to the (second) acoustic transfer function corresponding to the (second) vertical thickness of the voice coil of a VCA such as the VCA500 of Figures 5A-5B according to one embodiment. According to one embodiment, the vertical thickness of the voice coil 517 (Figures 5A-5B) is greater than the vertical thickness of the voice coil 217 (Figures 2B-2C), and is configured to increase the (second) coil torsion (CT) frequency of the second acoustic transfer function to near the (first) coil torsion (CT) frequency of the first acoustic transfer function. Similarly, according to one embodiment, the vertical thickness of the voice coil 517 is configured to increase the (second) rotational pivot tilt (PT) frequency of the second acoustic transfer function to near the (first) rotational pivot tilt (PT) frequency of the first acoustic transfer function. Thus, the increased thickness of the voice coil 517 promotes, generates, and enables non-trivial increases in CT frequency 613 and PT frequency 614. Analysis in the context of a 1-inch form factor, 3.5-inch diameter disk HDD with 10 or more disks shows that a voice coil vertical thickness in the range of 3.4 mm to 4.0 mm (3.4 mm to 4 mm) is suitable for the purposes described above. Therefore, considering the above, by combining a relatively short bearing span with a relatively thick voice coil, it is possible to maintain relatively high CT and PT frequencies while ensuring a relatively low PT gain.

[0023] Combination of shortened span rotary pivot bearing assembly and increased thickness voice coil assembly Figure 7A shows the HSA frequency response function corresponding to the operating vibration of the HDD rotary pivot bearing assembly of Figure 2A and the HDD voice coil actuator assemblies of Figures 2B-2C, according to one or more embodiments, and Figure 7B shows the HSA frequency response function corresponding to the operating vibration of the shortened span HDD rotary pivot bearing assembly of Figure 3 and the increased thickness voice coil of Figures 5A-5B. Thus, Figure 7A corresponds to the configuration combination of bearing assembly 200 (Figure 2A) together with VCA 210 (Figures 2B-2C), and Figure 7B corresponds to the configuration combination of bearing assembly 300 (Figure 3) together with VCA 500 (Figures 5A-5B). As described above, the non-repetitive runout of the final customer box (also referred to herein as "operating vibration") can be calculated as the product of the acoustic TF, the sound pressure profile of the customer box, and the error transfer function (ETF) of the servo controller. Each of Figures 7A-7B represents the FRF corresponding to the operating vibration of the HSA / head corresponding to the above configuration.

[0024] These acoustic TF diagrams show, in one embodiment, a (first) PT702 (Figure 7A) corresponding to the (first) acoustic transfer function corresponding to the (first) bearing span and (first) vertical thickness of the voice coil of the VCA, such as when the bearing assembly 200 is used with the VCA210, and a (second) PT712 (Figure 7B) corresponding to the (second) acoustic transfer function corresponding to the (second) bearing span and (second) vertical thickness of the voice coil of the VCA, such as when the bearing assembly 300 is used with the VCA500. Here, the shortened span bearing assembly 300 promotes, causes, and enables a non-trivial reduction in the NRRO PT gain (in this non-limiting example, a reduction of about 0.086 nm, or about 95%). Furthermore, the increased thickness voice coil 517 of the VCA 500 promotes, generates, and enables non-trivial CT frequency increases 713 and PT frequency increases 714 compared to the corresponding intermediate values ​​for a configuration with shortened span bearings only, where such intermediate values ​​are indicated by the leftmost dashed line for the CT frequency increases 713 and PT frequency increases 714 shown in the figure. The analysis shows that the PT gain difference in NRRO is significantly larger than the PT gain difference in acoustic TF alone. This is because both the customer box sound pressure profile (SP) and the servo controller error transfer function (ETF) decrease in magnitude from 6kHz to 7kHz. Therefore, the higher the PT frequency, the smaller the SP / ETF amplification of NRRO in PT. Again, considering the above, the combination of a relatively short bearing span and a relatively thick voice coil allows for relatively high CT and PT frequencies while simultaneously keeping the PT gain relatively low, thereby improving the NRRO associated with the structural dynamics and operating vibrations of the system.

[0025] 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 one embodiment, a plan view showing a conventional HDD 100 is shown in Figure 1 to help illustrate how a conventional HDD typically operates.

[0026] 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 at least one head gimbal assembly (HGA) 110 containing the head slider, a lead suspension 110c typically 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, but 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 may be fixed to the spindle 124 with disk clamps 128.

[0027] 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 assembly of a voice coil motor (VCM) including an armature 136 housing a voice coil 140 and attached to the carriage 134, 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 mounted together on a rotating pivot shaft 148 via a rotating 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.

[0028] An assembly comprising a head gimbal assembly (e.g., HGA110) 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, 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.

[0029] Referring further to Figure 1, electrical signals comprising write signals to head 110a 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," "baseplate," or simply "base"), together with the HDD cover (removed here to show the internal components), provides a semi-sealed (or, in some configurations, hermetically sealed) protective enclosure for the information storage components of the HDD 100.

[0030] 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 rotate while providing torque to the spindle 124, which 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 generates 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, in a non-limiting example, in an HDD using a gas lighter than air, such as helium, the rotating medium 120 generates a gas cushion on which the slider 110b rests, acting as a gas bearing or fluid bearing.

[0031] The electrical signals supplied to the voice coil 140 of the VCM enable the head 110a of the HGA 110 to access track 176 where 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. 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 portions 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 controls the electrical signal provided to the voice coil 140 of the VCM, thereby enabling the head 110a to follow track 176. Upon finding track 176 and identifying a specific sectored track portion 188, the head 110a reads information from track 176 or writes information to track 176 in response to instructions received by an external agent, such as a disk controller from a microprocessor of a computer system.

[0032] 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, but 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.

[0033] References to hard disk drives in this specification, such as HDD100 shown and described with reference to Figure 1, may also include 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. In non-limiting embodiments, a hybrid drive may be designed and configured to operate and utilize the solid-state portion in several ways, such as by using solid-state memory that stores frequently accessed data and I / O (input / output) aggregated data as cache memory. 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.

[0034] 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. Therefore, 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 the present invention, and of what the applicants intend to be the present invention, is the set of claims derived from this application, which constitute a particular form from which such claims derive, including any subsequent amendments. The definitions expressly provided herein for terms included in such claims shall govern the meaning of terms as used in the claims. Therefore, no limitations, elements, characteristics, features, advantages, or attributes not expressly provided in the claims shall in any way limit such claims. Accordingly, this specification and the drawings are to be considered illustrative and not restrictive.

[0035] In this specification, specific process steps may be described in a specific order, and specific 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 the steps and are not intended to specify or require a particular order in which such steps are performed.

Claims

1. A data storage device, A disk medium rotatably mounted on a spindle, A head slider equipped with a read-write head configured to write to and read from the disk media, A rotary actuator configured to move the head slider around a rotary pivot, wherein the rotary pivot includes a rotary pivot bearing and accesses a portion of the disk medium via operation by a voice coil motor assembly (VCMA), and It comprises an enclosure with a cover attached to a base, A data storage device in which the rotating pivot bearing is configured with a bearing span smaller than the maximum available bearing span, based on the vertical distance between the base and the cover.

2. The data storage device according to claim 1, wherein the bearing span is configured to reduce the second rotational pivot tilt gain of a second corresponding acoustic transfer function, defined as the off-track displacement of the head slider due to a unit sound pressure excitation applied to the enclosure, with respect to the first rotational pivot tilt gain of a first corresponding acoustic transfer function corresponding to the maximum available bearing span.

3. The data storage device according to claim 1, wherein the bearing span is within the range of 5 millimeters or more and 13 millimeters or less.

4. The bearing span is configured to reduce the second rotational pivot tilt gain of a second corresponding acoustic transfer function, defined as the off-track displacement of the head slider due to a unit sound pressure excitation on the enclosure, with respect to the first rotational pivot tilt gain of a first corresponding acoustic transfer function corresponding to the maximum usable bearing span and the first vertical thickness of the voice coil of the VCMA, and The data storage device according to claim 1, wherein the second acoustic transfer function further corresponds to a second vertical thickness of the voice coil, the second vertical thickness being greater than the first vertical thickness of the voice coil, and is configured to increase the second coil torsion frequency of the second acoustic transfer function to a frequency close to the first coil torsion frequency of the first acoustic transfer function.

5. The data storage device according to claim 4, wherein the second vertical thickness is configured to increase the second rotational pivot tilt frequency of the second acoustic transfer function to near the first rotational pivot tilt frequency of the first acoustic transfer function.

6. The data storage device according to claim 5, wherein the second vertical thickness of the voice coil is within the range of 3.4 millimeters or more and 4.0 millimeters or less.

7. The data storage device according to claim 6, wherein the bearing span is within the range of 5 millimeters or more and 13 millimeters or less.

8. The data storage device according to claim 5, wherein the bearing span is within the range of 5 mm or more and 13 mm or less.

9. The bearing span is configured to reduce the second rotational pivot tilt gain of a second corresponding acoustic transfer function, defined as the off-track displacement of the head slider due to a unit sound pressure excitation applied to the enclosure, with respect to the first rotational pivot tilt gain of a first corresponding acoustic transfer function corresponding to the maximum usable bearing span and the first vertical thickness of the voice coil of the VCMA. The bearing span is configured to individually reduce the second coil torsion frequency of the second acoustic transfer function with respect to the first coil torsion frequency of the first acoustic transfer function, The bearing span is configured to individually reduce the second rotational pivot tilt frequency of the second acoustic transfer function with respect to the first rotational pivot tilt frequency of the first acoustic transfer function, The second acoustic transfer function corresponds to the second vertical thickness of the voice coil, and the second vertical thickness is greater than the first vertical thickness of the voice coil. The second vertical thickness is configured to individually increase the second coil torsion frequency of the second acoustic transfer function to a position closer to the first coil torsion frequency of the first acoustic transfer function than the coil torsion frequency of the bearing span, and The data storage device according to claim 1, wherein the second vertical thickness is configured to individually increase the second rotational pivot tilt frequency of the second acoustic transfer function to a position closer to the first rotational pivot tilt frequency of the first acoustic transfer function than the rotational pivot tilt frequency of the bearing span.

10. The data storage device according to claim 1, wherein the data storage device is configured as a hard disk drive substantially one inch thick in the direction from the base to the cover, and comprises ten or more disk media.

11. A data storage device, A rotary actuator configured to move a read-write transducer around a rotary pivot, wherein the rotary pivot includes a rotary pivot bearing and accesses a portion of the disk medium via operation by a voice coil motor assembly (VCMA), and It comprises an enclosure with a cover attached to a base, The rotational pivot bearing is configured with a bearing span smaller than the maximum usable bearing span, based on the vertical distance between the base and the cover, and reduces the second rotational pivot tilt gain of the second corresponding acoustic transfer function with respect to the first rotational pivot tilt gain of the first corresponding acoustic transfer function corresponding to the maximum usable bearing span and the first vertical thickness of the voice coil of the VCMA, and The second acoustic transfer function further corresponds to the second vertical thickness of the voice coil, and the second vertical thickness is configured to be greater than the first vertical thickness of the voice coil. The second coil torsion frequency of the second acoustic transfer function is increased to be close to the first coil torsion frequency of the first acoustic transfer function, and A data storage device that increases the second rotational pivot tilt frequency of the second acoustic transfer function to near the first rotational pivot tilt frequency of the first acoustic transfer function.

12. The data storage device according to claim 11, wherein the bearing span is within the range of 5 millimeters or more and 13 millimeters or less.

13. The data storage device according to claim 11, wherein the second vertical thickness of the voice coil is within the range of 3.4 millimeters or more and 4.0 millimeters or less.

14. The data storage device according to claim 13, wherein the bearing span is within the range of 5 millimeters or more and 13 millimeters or less.

15. The data storage device according to claim 11, wherein the data storage device is configured as a hard disk drive substantially one inch thick in the direction from the base to the cover, and further comprises ten or more disk media.

16. It is a hard disk drive (HDD), A disk medium rotatably mounted on a spindle, A means for reading from and writing to one of the aforementioned disk media, A rotary actuator configured to move the reading and writing means around a rotary pivot, wherein the rotary pivot includes a rotary pivot bearing that accesses a portion of the disk medium via an actuation by a voice coil motor assembly (VCMA), An enclosure with a cover attached to the base, and A hard disk drive (HDD) comprising means for reducing the second rotational pivot tilt gain of a second corresponding acoustic transfer function with respect to the first rotational pivot tilt gain of a first corresponding acoustic transfer function corresponding to the maximum usable bearing span.

17. The first acoustic transfer function further corresponds to the first voice coil of the VCMA, and The second acoustic transfer function further corresponds to the second voice coil of the VCMA, The HDD according to claim 16, further comprising means for increasing the second coil torsion frequency of the second acoustic transfer function to near the first coil torsion frequency of the first acoustic transfer function.

18. The HDD according to claim 17, further comprising means for increasing the second rotational pivot tilt frequency of the second acoustic transfer function to near the first rotational pivot tilt frequency of the first acoustic transfer function.

19. The first acoustic transfer function further corresponds to the first voice coil of the VCMA, and The second acoustic transfer function further corresponds to the second voice coil of the VCMA, The HDD according to claim 16, further comprising means for increasing the second rotational pivot tilt frequency of the second acoustic transfer function to near the first rotational pivot tilt frequency of the first acoustic transfer function.

20. The disk media comprises 10 or more disk media, The HDD according to claim 16, wherein the HDD has a substantially 1-inch thickness between the base and the cover.

Images