Reduces the deflection of the disk media in hard disk drives.

Abstract

A hard disk drive includes multiple disk media mounted on a spindle, where the outer diameter of each disk media is offset from the inner diameter of the disk media in the same direction along the rotation axis of the spindle, and a load / unload ramp positioned to align with the outer diameter of the disk media based on the offset. Thus, the irregular deflection of disk media associated with increasingly thinner disks is mitigated by grouping similarly characterized irregular disks together on a given spindle and compensating the ramp accordingly.

Description

Technical Field

[0001] (Cross - Reference to Related Applications) This application claims the benefit of U.S. Provisional Application No. 18 / 544,189, filed with the United States Patent and Trademark Office on December 18, 2023, entitled "Hard Disk Drive Disk Media Curvature Mitigation", the entire content of which is incorporated herein by reference for all purposes.

[0002] Embodiments of the present invention generally relate to hard disk drives, and in particular, may relate to an approach for mitigating the deflection of disk media within a hard disk drive.

Background Art

[0003] A hard disk drive (HDD) is a non - volatile memory device that stores digitally encoded data on one or more circular disks with magnetic surfaces, housed within a protective enclosure. 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, positioned above a specific location on the disk by an actuator. The read - write head uses a magnetic field to write data to the surface of the magnetic recording disk and read data from this surface. 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 recording disk, magnetizing small regions on this recording medium in sequence.

[0004] Increasing the storage capacity of hard disk drives (HDDs) is one of the ongoing goals of HDD technology evolution. In one form, this goal manifests as increasing the number of disks implemented within a given HDD. However, in many cases, it is necessary to maintain a standard form factor, as is partly characterized by the z-height of the HDD, which inherently presents a challenge in fitting more disks into a given HDD. More specifically, customer specifications and / or common design and operational constraints include load / unload requirements and operational shock (or "op-shock") requirements, which generally relate to the operational tolerances of the HDD against mechanical shock events. The challenge remains of increasing the number of disks while maintaining a standard form factor and reliably meeting load / unload and operational shock requirements.

[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 illustrating a hard disk drive according to one embodiment. [Figure 2] This is a side cross-sectional view illustrating a disk stack and a corresponding load / unload ramp. [Figure 3A] This is a side cross-sectional view illustrating a disk stack with reduced deflection and a corresponding load / unload ramp according to one embodiment. [Figure 3B]This is a side cross-sectional view illustrating a disk stack with reduced deflection and a corresponding load / unload ramp according to one embodiment. [Figure 4] This is a flowchart illustrating a method for assembling a hard disk drive according to one embodiment. [Modes for carrying out the invention]

[0007] Generally, approaches to mitigate disk media deflection in hard disk drives (HDDs) 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, or dimensions are not always or necessarily described precisely. For example, if a structure is described as "substantially perpendicular," the term has its obvious meaning, such as the sidewalls 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 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] background It should be noted that to increase storage capacity, the number of disks in a given form factor can be increased. As a result, thinner recording disks (or simply “disks”) can be conceivable. However, generally, the thinner the disk, the less control there is over its flatness, which is simply a fundamental consequence of the manufacturing process of the substrate and medium (such as the stress on the substrate caused by uneven magnetic plating deposited on each side of the disk). Non-planar (also called “non-planar,” “irregular,” or “distorted”) disks typically take one of several major shapes, such as bowl-shaped (e.g., concave), umbrella-shaped (e.g., convex), and saddle-shaped (e.g., shaped like a horse saddle, with the sides curved downwards to give the top a rounded shape).

[0012] Figure 2 is a side cross-sectional view illustrating a disk stack and corresponding load / unload ramps. The disk stack 200 comprises a plurality of recording disks 202a-202n (or “hard disk” or simply “disks”), such as magnetic recording disks, where n represents any number of disks that may vary depending on the mounting configuration (here, 10 disks). The disks 202a-202n are mounted on a spindle 204 for rotation. Typically, one or more load / unload (LUL) ramp structures 206 are provided adjacent to or somewhat overlapping with the disks 202a-202n. LUL ramp technology includes a mechanism for moving a head stack assembly (HSA), including read-write head sliders (see, for example, slider 110b including magnetic read-write head 110a in Figure 1), away from disks 202a-202n and securely positioning them on a cam-like structure. The cam typically includes a gently sloping portion on the side closest to the disk for each slider, which merges with a typically horizontal "retraction" region that may have a return mechanism for holding the corresponding slider in place. During the power-up sequence, for example, the read-write head (e.g., read-write head 110a) is loaded by moving the slider (e.g., slider 110b) away from the LUL ramp 206 and onto the surface of disks 202a-202n when the disk reaches a suitable rotational speed. Therefore, the terminology used is that the slider or HSA is “loaded” into or on the disk (i.e., away from the ramp) into an operating position, and “unloaded” from the disk to an idle position or the like (i.e., on the ramp).

[0013] However, with respect to irregular disks 202a-202n with insufficient flatness control, such as thinner disks (as an unspecified example, 0.45 mm thick), the disk stack 200 in Figure 2 (in an exaggerated form) illustrates that the random placement of irregular disks 202a-202n on the spindle 204 could frequently cause misalignment or displacement with the corresponding LUL ramp 206, which is problematic in operation. Therefore, increasing the number of disks in a given form factor remains challenging in terms of HDD load / unload and operating shock requirements, particularly due to the accumulation of tolerances in the disk stack and insufficient disk flatness.

[0014] Disk stack with reduced deflection According to one embodiment, the cumulative tolerance and operating shock performance of the disk stack of a hard disk drive (HDD) can be improved, for example, when disks of known shapes are arranged in specific controlled positions within the disk stack. Similarly, a LUL ramp can be designed to align the ramp tip with the expected disk height at the outer diameter (OD) of each disk.

[0015] Figure 3A is a side cross-sectional view illustrating a deflection-reduced disk stack and a corresponding load / unload ramp according to one embodiment. The disk stack 300 includes a plurality of recording disks 302a-302n (or simply “disks”), such as magnetic recording disks, where n represents any number of disks (here, 10), which may vary depending on the mounting configuration. The disks 302a-302n are rotatably mounted on a spindle 304. There is one or more load / unload (LUL) ramp structures 306 adjacent to or somewhat overlapping with the disks 302a-302n, which operate or function in the same way as, or similarly to, those described with reference to ramp 206 (Figure 2). Here, rather than randomly assembling the irregular discs onto the spindle 304, the discs 302a to 302n are classified according to their degree of irregularity (for example, before or during assembly onto the spindle), and similarly characterized irregular discs 302a to 302n are mounted together on the same spindle 304. For example, bowl-shaped discs are assembled together on the same spindle, and / or umbrella-shaped discs are each assembled together on the same spindle, and / or saddle-shaped discs are each assembled together on the same spindle. Here, all discs 302a to 302n are shown as umbrella-shaped (in an exaggerated form) for illustrative purposes, but each of the other irregular disc shapes can similarly be grouped and mounted on their respective spindles.

[0016] The key point is that, as illustrated and described with reference to the disk stack 200 in Figure 2, disks 302a to 302n having similar irregular shapes are assembled together to avoid random misalignment between disks 302a to 302n and their corresponding ramps (one or more) 306 (for example, the ramp tip closest to the disk may be used as a reference frame related to alignment). Thus, one way to characterize this approach to mounting configurations of irregular or non-planar disks is to describe the disk medium as having an outer diameter (OD) offset from its inner diameter (ID), and thus describe sets of irregular, non-planar, or warped disks, such as those referred to as bowl-shaped, umbrella-shaped, saddle-shaped, or others. In the embodiment shown in Figure 3A, the multiple disks 302a to 302n mounted on the spindle 306 consist of all disk medium mounted on the spindle 306, with their ODs offset in the same direction from their ID (for example, along the rotation axis 304r of the spindle).

[0017] Not only are similarly characterized (e.g., characterized based on the form and / or amount of the ID-OD offset) irregular disks 302a-302n mounted together on the same spindle 304, but according to one embodiment, the LUL ramp(s) 306 are positioned to align with (or be aligned with) the OD of the disk medium, i.e., disks 302a-302n. As described above, one approach to aligning the LUL ramp(s) 306 with a group of similarly characterized irregular disks 302a-302n is to align the ramp tip 306t (e.g., typically the main inclined portion of the ramp 306 closest to the disk medium) with the expected disk height at each outer diameter (OD) of the disk. It should be noted that such alignment may vary depending on the implementation, and other parts or points of the ramp 306 can generally serve as reference points for alignment with disks 302a-302n in the broader context of LUL ramp technology and the corresponding desired load and unload procedures of a given HDD design. That is, aligning the ramp 306 with disks 302a-302n does not necessarily require that the corresponding components be precisely aligned, such as aligning the endpoint of the ramp tip 306t with the OD point of disks 302a-302n, but other considerations of load / unload technology may be taken into account in the context of aligning the corresponding components.

[0018] It should be noted that the slider loading / unloading process is neither simple nor trivial. For example, the physical configuration of the ramp can affect the amount the slider is lifted and the speed at which it is loaded and unloaded. During unloading, the slider first moves upward away from the disc and then typically returns downward toward the disc; this phenomenon is referred to herein as the slider's "rebound." More specifically, the slider is gradually lifted by the mechanical interaction of lift tabs extending from the ends of the suspension load beam with the ramp slope, thereby lifting it on the ramp slope, while the Gram load on the slider gradually decreases. Here, the term "Gram load" generally refers to the spring load of the entire suspension and slider assembly. However, the air bearing surface (ABS) force of the slider includes not only a positive lift force for floating over the disc, but also a negative attractive force. Therefore, even while the gram load is decreasing, the slider is still being pulled towards the disc (by the attractive force) for a period of time until the ABS separates from or overcomes the attractive force. Once a sufficient rise is achieved to overcome the ABS force, the slider typically moves rapidly upward. Since the suspension (including the flexure) acts as a spring, once the slider moves high and then low (i.e., closer to the disc), it then continues a high-low loop (e.g., slider oscillation) with damping until the slider oscillation finally ends. The important point here is to reinforce the concept that properly aligning ramp 306 with the OD of discs 302a-302n is more complex and may require more considerations than simply physically aligning specific parts of the structure of the corresponding components in a straight line.

[0019] Furthermore, there are several ways in which the ramps 306 can be aligned with the disk media. For the sake of manufacturing simplification, according to one embodiment, the position of the ramps 306 and their alignment with disks 302a-302n are not performed adaptively for each HDD, but rather a common disk-ramp interface is designed to be static, for example, based on the average degree of disk irregularity (e.g., deflection or ID-OD offset). For example, if it is found that the non-planarity of disks has a certain offset over a considerable number of samples, the design and / or vertical positioning of the static ramps in the corresponding HDDs can be implemented accordingly. For example, in an HDD in which this deflection mitigation approach is implemented, the ramp seating surface of its corresponding structural base (see, for example, HDD housing 168 in Figure 1) may be machined slightly from the reference value to effectively lower or raise the ramps from the reference value. According to one embodiment, different ramps 306 may be used for each of the characteristic forms of the corresponding irregular disks 302a-302n. Alternatively, according to one embodiment, the bottom interface / mounting of the lamp 306 and its corresponding structural base can be implemented to be variable, and the lamp 306 can be assembled to the base at a variable height (for example, by using something similar to a set screw, in a non-limiting example) based on a particular characteristic form of the corresponding irregular disks 302a-302n mounted on the spindle 304.

[0020] Assembling a set of irregularly shaped umbrella-shaped discs 302a-302n together, as shown in Figure 3A, may be preferable, for example, to limit the risk of interference between the ramp and cover due to the accumulation of tolerances in the disc stack, which is greatest at the top disc 302a, but other irregular disc stack configurations are also considered. Figure 3B is a side cross-sectional view illustrating a deflection-reduced disc stack and a corresponding load / unload ramp according to one embodiment. Here again, rather than randomly assembling irregular discs onto the spindle 354, the discs are classified according to their degree of irregularity, and similarly characterized irregular discs are mounted together on the same spindle 354.

[0021] Here, the multiple disk media include disks 352-1a to 352-1m, which are disk media of the first group, where m represents an arbitrary number of disks that may vary depending on the mounting configuration (here, 5 disks), and disks 352-2a to 352-2n, which are disk media of the second group, where n represents an arbitrary number of disks that may vary depending on the mounting configuration (here, 5 disks). As shown in the figure, each of the disks of the first group, 352-1a to 352-1m, is rotatably mounted on the spindle 354 with its outer diameter offset from its inner diameter in the same first direction along the rotation axis 354r of the spindle 354, and each of the disks of the second group, 352-2a to 352-2n, is rotatably mounted on the spindle 354 with its outer diameter offset from its inner diameter in the same opposite second direction along the rotation axis 354r of the spindle 354. As illustrated for illustrative purposes, discs 352-1a to 352-1m are all bowl-shaped (in an exaggerated form), and discs 352-2a to 352-2n are all umbrella-shaped (in an exaggerated form).

[0022] Similarly, the LUL lamp includes a first lamp portion 356-1 and a second lamp portion 356-2. The first lamp portion 356-1 is positioned to align with the outer diameters of the first disks 352-1a to 352-1m, and the second lamp portion 356-2 is positioned to align with the outer diameters of the second disks 352-2a to 352-2n. For example, the upper lamp portion 356-1 may be shifted up by 20 μm (micrometer or micron) from a reference value, while the lower lamp portion 356-2 may be shifted down by 20 μm from the reference value, and both are aligned with their corresponding disk sub-laminates 352-1a to 352-1m and 352-2a to 352-2n, respectively. Further, according to an embodiment, the upper disks 352-1a to 352-1m may be grouped together based on their similar average irregularities (10-micron ID-OD offset), while the lower disks 352-2a to 352-2n may be grouped together based on their similar average irregularities (different from the upper disks 352-1a to 352-1m, 25-micron ID-OD offset). Thus, the upper lamp portion 356-1 is shifted up by about 10 μm from the reference value, while the lower lamp portion 356-2 is shifted down by about 25 μm from the reference value, and both are aligned with their corresponding disk sub-laminates 352-1a to 352-1m and 352-2a to 352-2n, respectively.

[0023] Method of assembling a hard disk drive FIG. 4 is a flow diagram illustrating a method of assembling a hard disk drive according to an embodiment. For example, the method of FIG. 4 can be used to construct the embodiment of the disk laminate illustrated and described with reference to FIGS. 3A-3B.

[0024] At block 402, the flatness of each of the plurality of disk media is determined. For example, the flatness or lack thereof of a group of disk media such as disks 302a - 302n (FIG. 3A), 352-1a - 352-1m (FIG. 3B), 352-2a - 352-2n (FIG. 3B) can be measured using any of a number of conventional measurement tools, machines, operations, etc. According to one embodiment, disks 302a - 302n, 352-1a - 352-1m, 352-2a - 352-2n are then classified based on the determined flatness and aligned within corresponding disk cassettes based on similar flatness, and the outer diameter is offset from the inner diameter in the same direction within each corresponding disk cassette so that the disk media from each disk cassette can be easily positioned on a spindle. Such prior alignment of the disk media within the corresponding disk cassettes can be performed, for example, as part of the media manufacturing / test process or as part of the HDD manufacturing / test process. If disks characterized similarly are aligned within a cassette, they can be continuously installed / assembled on a spindle according to normal manufacturing procedures.

[0025] In block 404, the disk media are positioned on the spindles such that the outer diameter of each disk medium is offset in the same direction from the inner diameter of the disk medium along the rotation axis of the spindle. For example, disks 302a to 302n, 352-1a to 352-1m, and 352-2a to 352-2n are positioned on their respective spindles 304 (Figure 3A) and 354 (Figure 3B) such that the OD of each disk is offset from the ID of the disk in the same direction along the rotation axes 304r and 354r of the spindles 304 and 354. In the case of the disk stack 300 in Figure 3A, all disks 302a to 302n are arranged in an umbrella shape with the OD offset lower than the ID. In the case of the disk stack 350 in Figure 3B, disks 352-1a to 352-1m are all arranged in a bowl shape with the OD offset higher than the ID, while disks 352-2a to 352-2n are all arranged in an umbrella shape with the OD offset lower than the ID.

[0026] According to one embodiment, after determining the flatness (block 402) and before positioning on the spindle (block 404), each disk medium is marked to determine whether it should be positioned on the spindle as a first group of disk mediums with its outer diameter offset from its inner diameter in the same first direction along the spindle's rotation axis, or as a second group of disk mediums with its outer diameter offset from its inner diameter in the same opposite second direction along the spindle's rotation axis. For example, discs 302a-302n and 352-2a-352-2n may all be marked similarly (e.g., with a barcode) to indicate that these discs, along with other discs of similar shape, will be assembled on their respective spindles 304, 354 as umbrella-shaped discs (OD lower than ID), while discs 352-1a-352-1m may all be marked similarly (e.g., with a barcode) to indicate that these discs, along with other discs of similar shape, will be assembled on their respective spindles 354 as bowl-shaped discs (OD higher than ID). Thus, each disc marking can be read during assembly (e.g., by a robotic machine) to determine how such discs 302a-302n, 352-1a-352-1m, and 352-2a-352-2n should be aligned and assembled on their corresponding spindles 304, 354. Instead of reading them during assembly, the marked discs 302a-302n, 352-1a-352-1m, and 352-2a-352-2n are classified according to their respective markings, aligned within the corresponding disc cassettes according to their markings, and the outer diameter may be offset in the same direction from the inner diameter within each corresponding disc cassette to facilitate positioning of the disc media from each disc cassette onto the spindle, with the outer diameter offset in the same direction from the inner diameter.

[0027] According to one embodiment, disks 302a to 302n, 352-1a to 352-1m, and 352-2a to 352-2n are classified based on a determined flatness, packaged into corresponding disk cassettes based on type, form, or characterization, and the disk cassettes can be assigned to corresponding disk installation stations based on type.

[0028] In block 406, the load / unload (LUL) ramps are positioned relative to the outer diameter of the disk media. For example, ramps 306 (Figure 3A), 356-1, and 356-2 (Figure 3B) are positioned in alignment with or relative to the OD of the respective disks 302a-302n, 352-1a-352-1m, and 352-2a-352-2n, as will be described in more detail elsewhere in this specification. Thus, alignment errors between the disks and ramps are minimized, improving load / unload tolerances and operating shock performance, and allowing more disks to be added to the same standard HDD form factor.

[0029] Illustrative physical explanation of the underlying mechanism 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.

[0030] 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 rotatably mounted on a spindle 124, and a drive motor (invisible) attached to the spindle 124 for rotating the medium 120. The read-write head 110a, which may also be referred to as a transducer, includes a write element and a read element for writing and reading information stored in the medium 120 of the HDD 100, respectively. The media 120 or more disk media may be fixed to the spindle 124 with disk clamps 128.

[0031] The HDD 100 further includes an arm 132 attached to the HGA 110, a carriage 134, and a voice coil motor (VCM) including an armature 136 with a voice coil 140 attached to the carriage 134 and a stator 144 with a voice coil magnet (invisible). The armature 136 of the VCM is attached to the carriage 134 and is configured to move the arm 132 and the HGA 110 to access a portion of the media 120, all together mounted on a pivot shaft 148 by an intervening 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 interlocking arms that gives the carriage a comb-like appearance.

[0032] 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.

[0033] 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-electronic (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, provides a semi-sealed (or, in some configurations, hermetically sealed) protective enclosure for the information storage components of the HDD 100.

[0034] 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 attached to the spindle 124. As a result, the medium 120 rotates in direction 172. The rotating medium 120 forms an air cushion on which the air-bearing surface (ABS) of the slider 110b acts as an air bearing, 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.

[0035] 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 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.

[0036] 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.

[0037] 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 as cache memory to store frequently accessed data, I / O aggregated data, etc. 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.

[0038] 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.

[0039] 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, 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. It is a hard disk drive (HDD), A plurality of disk media rotatably mounted on a spindle, wherein the outer diameter of each disk media is offset in the same direction from the inner diameter of the disk media along the rotation axis of the spindle, An HDD comprising: a load / unload (LUL) ramp positioned to align with the outer diameter of the disk medium based on the offset.

2. The HDD according to claim 1, wherein the plurality of disk media consist of all of the disk media attached to the spindle.

3. The plurality of disk media include a first group of disk media and a second group of disk media, The LUL lamp includes a first lamp portion and a second lamp portion. Each of the disk media in the first group is rotatably mounted on the spindle having an outer diameter offset from the inner diameter in the same first direction along the rotation axis of the spindle, The first ramp portion is positioned to align with the outer diameter of the first group of disk media based on the offset in the first direction, Each of the disk media of the second group is rotatably mounted on the spindle having an outer diameter offset from the inner diameter in the same opposite second direction along the rotation axis of the spindle, The second ramp portion is positioned to align with the outer diameter of the second group of disk media based on the offset in the second direction. The HDD according to claim 1.

4. The HDD according to claim 3, wherein the first group of disk media consists of the upper half of the disk media mounted on the spindle, and the second group of disk media consists of the lower half of the disk media mounted on the spindle.

5. The HDD according to claim 1, wherein each of the plurality of disk media has a thickness of substantially 0.5 millimeters (mm) or less.

6. Multiple head sliders, each housing a read-write transducer configured to read from and write to each of the aforementioned multiple disk media, An actuator configured to move the head slider to access the portion of the disk medium, The HDD according to claim 1, further comprising the following:

7. This is a method for assembling a hard disk drive. Determining the flatness of each disk medium among multiple disk media, The disk media are positioned on the spindle such that the outer diameter of each disk media is offset in the same direction from the inner diameter of the disk media along the rotation axis of the spindle, A method comprising positioning a load / unload (LUL) ramp relative to the outer diameter of the disk medium based on the offset.

8. The method according to claim 7, wherein positioning the disk media includes positioning all of the disk media such that the outer diameter of the disk media is offset in the same direction from the inner diameter of the disk media.

9. The plurality of disk media include a first group of disk media and a second group of disk media, The LUL lamp includes a first lamp portion and a second lamp portion. Positioning the aforementioned disk medium is Each of the disk media in the first group is positioned along the rotation axis of the spindle in the same first direction, such that the outer diameter of the disk media in the first group is offset from the inner diameter of the disk media in the first group. This includes positioning each of the disk media of the second group in the same opposite second direction along the rotation axis of the spindle, such that the outer diameter of the disk media of the second group is offset from the inner diameter of the disk media of the second group, Positioning the LUL lamp is Based on the offset in the first direction, the first ramp portion is positioned to align with the outer diameter of the first group of disk media, Based on the offset in the second direction, the second ramp portion is positioned to align with the outer diameter of the second group of disk media, The method according to claim 7, including the method described in claim 7.

10. The method according to claim 9, wherein positioning the first group of disk media includes positioning the first group as the upper half of the disk media, and positioning the second group of disk media includes positioning the second group as the lower half of the disk media.

11. Classifying the plurality of disk media based on the flatness determined above, To position the disk media on the spindle from each disk cassette such that the outer diameter of the disk media is offset in the same direction from the inner diameter of the disk media, the classified disk media are aligned within the corresponding disk cassettes based on similar flatness and such that the outer diameter of the disk media is offset in the same direction from the inner diameter of the disk media within each corresponding disk cassette. The method according to claim 7, further comprising:

12. After determining the flatness, and before positioning the disk media on the spindle, mark each disk media to determine whether it should be positioned on the spindle as a first group of disk media where the outer diameter of the disk media is offset from the inner diameter of the disk media in the same first direction along the rotation axis of the spindle, or as a second group of disk media where the outer diameter of the disk media is offset from the inner diameter of the disk media in the same opposite second direction along the rotation axis of the spindle. The method according to claim 7, further comprising:

13. The plurality of disk media are classified based on the markings on the plurality of disk media, Based on the markings on the plurality of disk media, the classified disk media are aligned within the corresponding disk cassette such that the outer diameters of the plurality of disk media are offset in the same direction from the inner diameters of the plurality of disk media within each corresponding disk cassette. The method according to claim 12, further comprising:

14. Based on the flatness determined above, the plurality of disk media are classified according to type, The aforementioned disk media is packaged into a corresponding disk cassette based on the aforementioned type, Assigning the aforementioned disc cassette to the corresponding disc installation station based on the aforementioned type, The method according to claim 7, further comprising:

15. It is a hard disk drive (HDD), A disk stack comprising a plurality of disk media rotatably mounted on a spindle, wherein the outer diameter of each disk media is offset in the same direction from the inner diameter of the disk media along the rotation axis of the spindle, Each of the head sliders houses a read-write transducer configured to read from and write to each disk medium of the disk stack, Means for moving the plurality of head sliders to access the portion of the disk medium, An HDD comprising means for supporting the loading of the head slider onto the disk stack, which is positioned to align with the outer diameter of the disk medium based on the offset of the disk medium, and means for supporting the unloading of the head slider from the disk stack.

16. The HDD according to claim 15, wherein the plurality of disk media consist of all of the disk media attached to the spindle.

17. The plurality of disk media include a first group of disk media and a second group of disk media, The LUL lamp includes a first lamp portion and a second lamp portion. Each of the disk media in the first group is rotatably mounted on the spindle having an outer diameter offset from the inner diameter in the same first direction along the rotation axis of the spindle, The first ramp portion is positioned to align with the outer diameter of the first group of disk media based on the offset in the first direction, Each of the disk media of the second group is rotatably mounted on the spindle having an outer diameter offset from the inner diameter in the same opposite second direction along the rotation axis of the spindle, The second ramp portion is positioned to align with the outer diameter of the second group of disk media based on the offset in the second direction. The HDD according to claim 15.

18. The HDD according to claim 17, wherein the first group of disk media consists of the upper half of the disk media mounted on the spindle, and the second group of disk media consists of the lower half of the disk media mounted on the spindle.

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