Magnetic disk drive
The magnetic disk device addresses clamp rigidity issues by expanding the clamp's outer surface to match disk inner diameters and using a retaining wall to uniformly distribute fixing forces, improving rigidity and reducing disk warping for stable operations.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- KK TOSHIBA
- Filing Date
- 2025-01-10
- Publication Date
- 2026-07-23
AI Technical Summary
Magnetic disk devices face issues with clamp rigidity, leading to warping of magnetic disks during rotation, which affects reading and writing operations.
A magnetic disk device design incorporating a hub with a support wall and a clamp that holds spacers and disks, enhancing rigidity by expanding the clamp's outer circumferential surface to match the disk's inner surface diameter, and using a retaining wall to uniformly distribute fixing forces.
The design improves clamp rigidity, reducing disk warping and ensuring stable disk positioning, thereby enhancing data reading and writing accuracy.
Smart Images
Figure 2026120931000001_ABST
Abstract
Description
Technical Field
[0001] Embodiments of the present invention relate to a magnetic disk device.
Background Art
[0002] A magnetic disk device such as a hard disk drive (HDD) has a plurality of magnetic disks and a motor that rotates the plurality of magnetic disks. The motor has a hub that fits into holes of the plurality of magnetic disks, and a clamp that is attached to the hub and holds the plurality of magnetic disks.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] When the rigidity of the clamp is low, the magnetic disk may warp during rotation.
[0005] An example of the problem to be solved by the present invention is to provide a magnetic disk device capable of improving the rigidity of the clamp.
Means for Solving the Problems
[0006] A magnetic disk device according to one embodiment comprises a housing, a motor, a plurality of magnetic disks, and a plurality of spacers. The motor has a hub housed in the housing and mounted to the housing so as to be rotatable about a rotation axis relative to the housing, and a clamp attached to the hub. The plurality of magnetic disks are arranged along the rotation axis and attached to the motor. The plurality of spacers are each located between two adjacent magnetic disks or between the clamp and one of the plurality of magnetic disks, and are attached to the motor. Each of the plurality of magnetic disks has a first inner surface facing the rotation axis. Each of the plurality of spacers has a second inner surface facing the rotation axis. The hub has a support wall that supports the plurality of magnetic disks and the plurality of spacers, and a first outer surface that extends from the support wall in a direction extending along the rotation axis, supporting the first inner surface of at least one of the plurality of magnetic disks and supporting the second inner surface of at least one of the plurality of spacers. The clamp has a second outer surface that supports the second inner surface of at least one of the plurality of spacers, and a retaining wall that protrudes from the second outer surface, and holds the plurality of magnetic disks and the plurality of spacers between the support wall and the retaining wall. [Brief explanation of the drawing]
[0007] [Figure 1] Figure 1 is an illustrative perspective view showing a disassembled HDD according to the first embodiment. [Figure 2] Figure 2 is an exemplary cross-sectional view showing a portion of the HDD of the first embodiment. [Figure 3] Figure 3 is an exemplary cross-sectional view showing a portion of the vicinity of the HDD clamp in the first embodiment. [Figure 4] Figure 4 is an exemplary cross-sectional view showing a portion of the vicinity of the clamp of the HDD according to the second embodiment. [Figure 5] Figure 5 is an exemplary cross-sectional view showing a portion of the vicinity of the clamp of the HDD according to the third embodiment. [Figure 6] Figure 6 is an exemplary cross-sectional view showing a portion of the vicinity of the clamp of the HDD according to the fourth embodiment. [Modes for carrying out the invention]
[0008] (First embodiment) The first embodiment will be described below with reference to Figures 1 to 3. Note that in this specification, the components of the embodiment and their descriptions may be described using multiple expressions. The components and their descriptions are examples and are not limited by the expressions used herein. Components may also be identified by names different from those used herein. Furthermore, components may also be described using expressions different from those used herein.
[0009] In the following explanation, “suppress” is defined, for example, to prevent the occurrence of an event, action, or effect, or to reduce the degree of an event, action, or effect. Also, in the following explanation, “restrict” is defined, for example, to prevent movement or rotation, or to permit movement or rotation within a predetermined range while preventing movement or rotation beyond that predetermined range.
[0010] Figure 1 is an exemplary perspective view showing a disassembled hard disk drive (HDD) 10 according to the first embodiment. The HDD 10 is an example of a magnetic disk device and may also be referred to as an electronic device, a storage device, an external storage device, or a disk device.
[0011] As shown in each drawing, for convenience, a first direction D1 and a second direction D2 are defined herein. The first direction D1 is an example of an extension direction. The first direction D1 is one direction along the thickness of the HDD 10. The second direction D2 is the opposite direction to the first direction D1.
[0012] Figure 2 is an exemplary cross-sectional view showing a part of the HDD 10 of the first embodiment. The HDD 10 includes a housing 11, a spindle motor 12, a plurality of magnetic disks 13, and a plurality of spacers 14 as shown in Figure 2, and a head stack assembly (HSA) 15, a voice coil motor (VCM) 16, a ramp load mechanism 17, and a printed circuit board (PCB) 18 as shown in Figure 1. The spindle motor 12 is an example of a motor.
[0013] As shown in Figure 2, the housing 11 has a base 21, an inner cover 22, an outer cover 23, and a shaft 24. As shown in Figure 1, the base 21 is formed in the shape of a roughly rectangular box that is open in a first direction D1. The housing 11 houses a spindle motor 12, a magnetic disk 13, a spacer 14, an HSA 15, a VCM 16, and a ramp load mechanism 17 in the space S inside the base 21.
[0014] The base 21 has a bottom wall 25 and side walls 26. The bottom wall 25 is formed in the shape of a roughly rectangular (quadrilateral) plate, arranged to be substantially perpendicular to the first direction D1 and the second direction D2. The side walls 26 project from the edge of the bottom wall 25 in the first direction D1 and are formed in the shape of a roughly rectangular frame.
[0015] The inner cover 22 is attached, for example, by screws to the end of the side wall 26 in the first direction D1, and closes the space S inside the base 21. The outer cover 23 covers the inner cover 22 and is attached, for example, by welding to the end of the side wall 26 in the first direction D1.
[0016] After components are installed inside the base 21 and the inner cover 22 and outer cover 23 are attached to the base 21, the air inside the housing 11 is removed through the vents provided in the inner cover 22 and outer cover 23. Furthermore, the inside of the housing 11 is filled with a gas other than air.
[0017] The gas filled inside the housing 11 is, for example, a low-density gas with a lower density than air, an inert gas with low reactivity, or the like. For example, helium is filled inside the housing 11. Note that other fluids may be filled inside the housing 11. The ventilation holes of the outer cover 23 are blocked by seals. Thereby, the space S is hermetically sealed.
[0018] As shown in FIG. 2, the shaft 24 protrudes from the bottom wall 25 in the first direction D1. The shaft 24 is formed in a substantially cylindrical shape extending along the rotation axis Ax. The rotation axis Ax is, for example, the central axis of the shaft 24 and extends in the first direction D1 and the second direction D2. That is, the first direction D1 and the second direction D2 are each directions along the rotation axis Ax. Note that the central axis of the shaft 24 may be deviated from the rotation axis Ax.
[0019] Hereinafter, for convenience, the radial direction and the circumferential direction are defined. The radial direction is a direction orthogonal to the rotation axis Ax. The radial direction includes a plurality of directions orthogonal to the rotation axis Ax. The circumferential direction is a direction around the rotation axis Ax. The circumferential direction includes the clockwise direction and the counterclockwise direction around the rotation axis Ax.
[0020] The end portion of the shaft 24 in the second direction D2 is fixed to the bottom wall 25. The end portion of the shaft 24 in the first direction D1 is attached to the inner cover 22 by, for example, a screw 27. Note that the shaft 24 is not limited to this example.
[0021] The spindle motor 12 has, for example, a plurality of coils 31, a hub 32, a plurality of magnets 33, a clamp 34, and a plurality of screws 35. Note that the spindle motor 12 is not limited to this example.
[0022] The plurality of coils 31 are arranged at substantially equal intervals in the circumferential direction around the shaft 24. The plurality of coils 31 are held by, for example, the base 21 and are electrically connected to a PCB 18 located outside the housing 11, for example.
[0023] The hub 32 is mounted on the shaft 24 of the housing 11 so as to be rotatable around the rotation axis Ax relative to the housing 11. The hub 32 has a hub cylinder 41, a support wall 42, and a projection 43.
[0024] The hub cylinder 41 is formed in a substantially cylindrical shape that extends along the axis of rotation Ax. The hub cylinder 41 has two end faces 41a, 41b and an outer circumferential surface 41c. The outer circumferential surface 41c is an example of a first outer circumferential surface.
[0025] The end face 41a is the end face of the hub cylinder 41 in the first direction D1, and the whole structure faces the first direction D1. The end face 41b is located on the opposite side of the end face 41a. That is, the end face 41b is the end face of the hub cylinder 41 in the second direction D2, and the whole structure faces the second direction D2. The outer circumferential surface 41c is a substantially cylindrical curved surface extending along the axis of rotation Ax. The outer circumferential surface 41c faces radially outward. The diameter of the outer circumferential surface 41c is, for example, approximately 25.0 mm. Note that the diameter of the outer circumferential surface 41c is not limited to this example.
[0026] The hub cylinder 41 is provided with a central hole 45, a groove 46, and a number of screw holes 47. The central hole 45 penetrates the hub cylinder 41 along the rotation axis Ax and opens into two end faces 41a and 41b. The shaft 24 extends through the central hole 45. This allows the hub cylinder 41 of the hub 32 to be mounted on the shaft 24 so as to be rotatable around the rotation axis Ax. Between the shaft 24 and the hub cylinder 41, for example, a fluid dynamic bearing is provided.
[0027] The groove 46 opens into the end face 41b of the hub cylinder 41 and extends in the circumferential direction. Each of the multiple coils 31 is positioned at least partially inside the groove 46. Furthermore, each of the multiple magnets 33 is positioned inside the groove 46 and attached to the hub cylinder 41. The multiple magnets 33 are arranged at approximately equal intervals in the circumferential direction.
[0028] Multiple screw holes 47 open into the end face 41a of the hub cylinder 41 and are arranged at equal intervals in the circumferential direction. The number of screw holes 47 is greater than or equal to the number of screws 35. Each of the screw holes 47 is provided with a female thread.
[0029] The support wall 42 protrudes radially outward from the end of the outer circumferential surface 41c of the hub cylinder 41 in the second direction D2. Therefore, the outer circumferential surface 41c extends from the support wall 42 in the first direction D1. The support wall 42 is formed in a substantially annular shape that extends in the circumferential direction. The support wall 42 has a support surface 42a. The support surface 42a is formed to be substantially flat and faces the first direction D1.
[0030] The projection 43 protrudes from the end face 41a of the hub cylinder 41. In the radial direction, the projection 43 is located between the central hole 45 and the screw hole 47. The projection 43 may be formed in an annular shape extending in the circumferential direction, or it may have multiple projections arranged in the circumferential direction.
[0031] The projection 43 has a mating surface 43a. The mating surface 43a is an example of a third outer surface. The mating surface 43a is, for example, the end face of the projection 43 on the radially outward side and faces radially outward. When the projection 43 is formed in an annular shape, the mating surface 43a is formed in a substantially cylindrical shape extending along the axis of rotation Ax. Note that the mating surface 43a is not limited to this example and may face, for example, in an oblique direction. The diameter of the mating surface 43a is, for example, about 13.6 mm. Note that the diameter of the mating surface 43a is not limited to this example.
[0032] Figure 3 is an exemplary cross-sectional view showing the vicinity of the clamp 34 of the HDD 10 in the first embodiment. As shown in Figure 3, the clamp 34 is attached to the hub 32. The clamp 34 has a clamp cylinder 51 and a retaining wall 52.
[0033] The clamp cylinder 51 is formed in a substantially cylindrical shape extending along the axis of rotation Ax. The clamp cylinder 51 has two end faces 51a and 51b, an outer circumferential surface 51c, and an inner circumferential surface 51d. The outer circumferential surface 51c is an example of a second outer circumferential surface. The inner circumferential surface 51d is an example of a third inner circumferential surface.
[0034] End face 51a is the end face of the clamp cylinder 51 in the first direction D1, and the whole structure faces the first direction D1. End face 51b is located on the opposite side of end face 51a. That is, end face 51b is the end face of the clamp cylinder 51 in the second direction D2, and the whole structure faces the second direction D2.
[0035] The distance between end faces 51a and 51b in the direction along the rotation axis Ax (the thickness of the clamp 34) is, for example, approximately 2.3 mm. Note that the thickness of the clamp 34 is not limited to this example.
[0036] The outer circumferential surface 51c is a substantially cylindrical curved surface extending along the axis of rotation Ax. The outer circumferential surface 51c faces radially outward. The diameter of the outer circumferential surface 51c is approximately equal to the diameter of the outer circumferential surface 41c of the hub cylinder 41. Note that the diameter of the outer circumferential surface 51c may be smaller or larger than the diameter of the outer circumferential surface 41c of the hub cylinder 41.
[0037] The inner circumferential surface 51d is located on the opposite side of the outer circumferential surface 51c. The inner circumferential surface 51d faces radially inward. That is, the inner circumferential surface 51d faces the axis of rotation Ax. Note that the inner circumferential surface 51d may also face, for example, an oblique direction.
[0038] The diameter of the inner circumferential surface 51d is, for example, approximately 13.6 mm. That is, the diameter of the inner circumferential surface 51d is slightly larger than the diameter of the mating surface 43a of the projection 43 of the hub 32. Note that the diameter of the inner circumferential surface 51d is not limited to the example above.
[0039] The clamp cylinder 51 is provided with a fitting hole 55 and a plurality of through holes 56. The fitting hole 55 is defined by the inner circumferential surface 51d and penetrates the clamp cylinder 51 along the rotation axis Ax. Therefore, the fitting hole 55 opens into two end faces 51a and 51b. The plurality of through holes 56 are arranged at approximately equal intervals in the circumferential direction. Each of the plurality of through holes 56 penetrates the clamp cylinder 51 and opens into two end faces 51a and 51b.
[0040] The projection 43 of the hub 32 is fitted into the fitting hole 55. The fitting surface 43a of the projection 43 contacts, at least partially, the inner circumferential surface 51d of the clamp cylinder 51. As a result, the fitting surface 43a supports the inner circumferential surface 51d and restricts the clamp 34 from moving radially relative to the hub 32.
[0041] The number of through holes 56 is greater than or equal to the number of screw holes 47 in the hub 32. Each of the through holes 56 communicates with a corresponding screw hole 47. The screws 35 are fitted into the screw holes 47 through the through holes 56. In this way, the screws 35 attach the clamp cylinder 51 of the clamp 34 to the hub cylinder 41 of the hub 32.
[0042] The retaining wall 52 protrudes radially outward from the end of the outer circumferential surface 51c of the clamp cylinder 51 in the first direction D1. Therefore, the outer circumferential surface 51c extends from the retaining wall 52 in the second direction D2. The retaining wall 52 is formed in a substantially annular shape that extends in the circumferential direction.
[0043] The retaining wall 52 has a contact surface 52a. The contact surface 52a as a whole faces the second direction D2. As shown in Figure 2, the support surface 42a of the support wall 42 and the contact surface 52a of the retaining wall 52 face each other with a gap between them.
[0044] Each of the multiple magnetic disks 13 is formed in a substantially disc shape and is arranged to be substantially perpendicular to the rotation axis Ax. As shown in Figure 3, each of the multiple magnetic disks 13 has two planes 13a and 13b and an inner circumferential surface 13c. The inner circumferential surface 13c is an example of a first inner circumferential surface.
[0045] Plane 13a is the end face of the magnetic disk 13 in the first direction D1, and the plane as a whole is oriented in the first direction D1. Plane 13b is located on the opposite side of plane 13a. That is, plane 13b is the end face of the magnetic disk 13 in the second direction D2, and the plane as a whole is oriented in the second direction D2. A magnetic recording layer is provided on at least one of the two planes 13a and 13b.
[0046] The inner circumferential surface 13c is oriented radially inward as a whole. That is, the inner circumferential surface 13c is oriented toward the axis of rotation Ax. In the example in Figure 3, the inner circumferential surface 13c has a tapered surface that curves downward from the plane 13b in a first direction D1, a tapered surface that curves downward from the plane 13a in a second direction D2, and a substantially cylindrical curved surface that extends along the axis of rotation Ax between the two tapered surfaces. Note that the inner circumferential surface 13c is not limited to the example in Figure 3. The minimum diameter of the inner circumferential surface 13c is, for example, about 25.0 mm. Note that the diameter of the inner circumferential surface 13c is not limited to this example.
[0047] A disk hole 61 is provided in the magnetic disk 13. The disk hole 61 is defined on the inner circumferential surface 13c and penetrates the magnetic disk 13 along the rotation axis Ax. As a result, the disk hole 61 opens into two planes 13a and 13b.
[0048] Each of the multiple spacers 14 is formed in a substantially annular shape extending in the circumferential direction and is arranged to be substantially perpendicular to the axis of rotation Ax. Each of the multiple spacers 14 has two planes 14a, 14b and an inner circumferential surface 14c. The inner circumferential surface 14c is an example of a second inner circumferential surface.
[0049] Plane 14a is the end face of the spacer 14 in the first direction D1, and the plane as a whole is oriented in the first direction D1. Plane 14b is located on the opposite side of plane 14a. That is, plane 14b is the end face of the spacer 14 in the second direction D2, and the plane as a whole is oriented in the second direction D2.
[0050] The inner circumferential surface 14c is oriented radially inward as a whole. That is, the inner circumferential surface 14c is oriented toward the axis of rotation Ax. In the example in Figure 3, the inner circumferential surface 14c has a tapered surface that curves downward from the plane 14b in a first direction D1, a tapered surface that curves downward from the plane 14a in a second direction D2, and a substantially cylindrical curved surface that extends along the axis of rotation Ax between the two tapered surfaces. The minimum diameter of the inner circumferential surface 14c is, for example, about 25.1 mm. Note that the inner circumferential surface 14c is not limited to the example in Figure 3, nor is it limited to the diameter mentioned above.
[0051] A spacer hole 65 is provided in the spacer 14. The spacer hole 65 is defined on the inner circumferential surface 14c and penetrates the spacer 14 along the rotation axis Ax. As a result, the spacer hole 65 opens into two planes 14a and 14b.
[0052] Multiple magnetic disks 13 are arranged along the rotation axis Ax. Multiple spacers 14 are arranged alternately with the multiple magnetic disks 13 along the rotation axis Ax. In other words, the multiple magnetic disks 13 and the multiple spacers 14 are stacked alternately along the rotation axis Ax. Note that two or more of the multiple spacers 14 may be placed between two adjacent magnetic disks 13.
[0053] In the first embodiment, each of the multiple spacers 14 is positioned between two adjacent magnetic disks 13, maintaining the distance between the two magnetic disks 13. The plane 14a of each spacer 14 contacts the plane 13b of one magnetic disk 13 adjacent to the spacer 14 (for example, the upper one in Figure 2). The plane 14b of each spacer 14 contacts the plane 13a of another magnetic disk 13 adjacent to the spacer 14 (for example, the lower one in Figure 2).
[0054] As shown in Figure 2, the multiple magnetic disks 13 and the multiple spacers 14 are arranged between the support wall 42 of the hub 32 and the retaining wall 52 of the clamp 34. The multiple magnetic disks 13 and the multiple spacers 14 are attached to the spindle motor 12.
[0055] The support surface 42a of the support wall 42 supports the stacked magnetic disks 13 and spacers 14. The retaining wall 52 pushes the stacked magnetic disks 13 and spacers 14 toward the support wall 42, for example, by elastic force. As a result, the clamp 34 holds the magnetic disks 13 and spacers 14 between the support wall 42 and the retaining wall 52.
[0056] The multiple magnetic disks 13 include an upper magnetic disk 13U and multiple lower magnetic disks 13L. Note that the terms "upper" and "lower" in this embodiment are merely convenient designations based on the arrangement shown in Figure 2 and do not limit the orientation, position, or mode of use.
[0057] The uppermost magnetic disk 13U is the magnetic disk 13 closest to the retaining wall 52 among the multiple magnetic disks 13. The lower magnetic disks 13L are the remaining magnetic disks 13 among the multiple magnetic disks 13.
[0058] The multiple spacers 14 include an uppermost spacer 14U and multiple lower spacers 14L. The uppermost spacer 14U is the single spacer 14 closest to the retaining wall 52 among the multiple spacers 14. The multiple lower spacers 14L are the remaining spacers 14 among the multiple spacers 14.
[0059] In the first embodiment, the hub cylinder 41 of the hub 32 fits into the disk holes 61 of the plurality of lower magnetic disks 13L and the spacer holes 65 of the plurality of lower spacers 14L. As a result, the outer peripheral surface 41c of the hub cylinder 41 contacts the inner peripheral surface 13c of the lower magnetic disks 13L and the inner peripheral surface 14c of the lower spacers 14L.
[0060] The outer circumferential surface 41c supports the inner circumferential surface 13c of the lower magnetic disk 13L, restricting the lower magnetic disk 13L from moving radially relative to the hub 32. Furthermore, the outer circumferential surface 41c supports the inner circumferential surface 14c of the lower spacer 14L, restricting the lower spacer 14L from moving radially relative to the hub 32.
[0061] Meanwhile, the clamp cylinder 51 of the clamp 34 fits into the disk hole 61 of the uppermost magnetic disk 13U and the spacer hole 65 of the uppermost spacer 14U. As a result, the outer peripheral surface 51c of the clamp cylinder 51 comes into contact with the inner peripheral surface 13c of the uppermost magnetic disk 13U and the inner peripheral surface 14c of the uppermost spacer 14U.
[0062] The outer peripheral surface 51c supports the inner peripheral surface 13c of the uppermost magnetic disk 13U, restricting radial movement of the uppermost magnetic disk 13U relative to the clamp 34. Furthermore, the outer peripheral surface 41c supports the inner peripheral surface 14c of the uppermost spacer 14U, restricting radial movement of the uppermost spacer 14U relative to the clamp 34.
[0063] In the first embodiment, the uppermost magnetic disk 13U is located between the uppermost spacer 14U and the retaining wall 52. Therefore, the contact surface 52a of the retaining wall 52 contacts the plane 13a of the uppermost magnetic disk 13U.
[0064] As shown in Figure 3, the outer circumferential surface 41c of the hub cylinder 41 has an upper end 41e. The upper end 41e is the end of the outer circumferential surface 41c in the first direction D1. Also, the inner circumferential surface 14c of the spacer 14 has an upper end 14e. The upper end 14e is the end of the inner circumferential surface 14c in the first direction D1.
[0065] The upper end 41e of the outer peripheral surface 41c is closer to the support wall 42 than the entire uppermost magnetic disk 13U. Furthermore, the upper end 41e of the outer peripheral surface 41c is closer to the support wall 42 than the entire uppermost spacer 14U. For this reason, the upper end 41e of the outer peripheral surface 41c is closer to the support wall 42 than the upper end 14e of the inner peripheral surface 14c.
[0066] Furthermore, the end face 41a of the hub cylinder 41 is closer to the support wall 42 than the entire uppermost magnetic disk 13U. In addition, the end face 41a of the hub cylinder 41 is closer to the support wall 42 than the upper end 14e of the inner circumferential surface 14c.
[0067] The HSA15 shown in Figure 1 is mounted on a shaft 71. The shaft 71 is positioned radially away from the magnetic disk 13. The shaft 71 protrudes from the bottom wall 25 of the housing 11 in a first direction D1. The HSA15 can rotate around the shaft 71.
[0068] The HSA15 comprises a carriage 75, a plurality of head gimbal assemblies (HGAs) 76, and a flexible printed circuit board (FPC) 77.
[0069] The carriage 75 is rotatably supported on the shaft 71 via bearings. Multiple HGAs 76 and the voice coil of the VCM 16 are mounted on the carriage 75. The VCM 16 has the voice coil, a pair of yokes, and magnets provided on the yokes.
[0070] Each of the HGA76 units has a base plate 81, a load beam 82, a flexure 83, and a slider 84. The slider 84 may also be referred to as a head slider or magnetic head.
[0071] The base plate 81 is attached to the arms of the carriage 75. The load beam 82 is formed as a plate thinner than the base plate 81 and extends from the base plate 81. The flexure 83 is a type of flexible printed wiring board formed as a long, narrow strip.
[0072] The slider 84 is positioned at the tip of the HGA 76 and mounted on the flexi-shape 83. The slider 84 records and reproduces information on the magnetic recording layer of the planar 13a or planar 13b of the magnetic disk 13. In other words, the slider 84 reads and writes information to the magnetic disk 13.
[0073] One end of the FPC77 is attached to the carriage 75. The FPC77 is electrically connected to the slider 84 via the flexure 83. The other end of the FPC77 is attached to the bottom wall 25 of the base 21.
[0074] The VCM16 rotates the carriage 75 around the shaft 71. This allows the VCM16 to position the slider 84 at a desired location on the plane 13a or plane 13b of the magnetic disk 13. The VCM16 can also unload the slider 84 so that the HGA 76 is supported by the ramp load mechanism 17.
[0075] PCB18 is a rigid substrate, such as a glass epoxy substrate, and can be a multilayer substrate or a build-up substrate. PCB18 is placed outside the housing 11 and attached to the bottom wall 25 of the base 21.
[0076] The PCB 18 is equipped with various electronic components, such as a relay connector connected to the FPC 77, an interface (I / F) connector connected to a host computer, and a controller that controls the operation of the HDD 10. The relay connector is electrically connected to the FPC 77, for example, via a connector provided on the bottom wall 25.
[0077] PCB18 is electrically connected to slider 84 via FPC77 and flexi 83. A controller on PCB18 controls slider 84 to read and write information to magnetic disk 13. Furthermore, PCB18 is electrically connected to coil 31 of spindle motor 12 and controls spindle motor 12.
[0078] When the PCB 18 inputs an electrical signal to the coil 31, the spindle motor 12 rotates the hub 32 around the rotation axis Ax. As a result, the multiple magnetic disks 13, the multiple spacers 14, and the clamp 34 also rotate around the rotation axis Ax.
[0079] If the clamp 34 has low rigidity, the force exerted by the multiple screws 35 to secure the clamp 34 to the hub 32 may deform the clamp 34. Furthermore, the force exerted by the multiple screws 35 to secure the clamp 34 to the hub 32 may be transmitted unevenly to the multiple magnetic disks 13. In this case, the rotating multiple magnetic disks 13 may warp (bend or flex).
[0080] When the magnetic disk 13 warps, the planes 13a and 13b of the magnetic disk 13 are displaced in the first direction D1 or the second direction D2 relative to the housing 11. As a result, the distance between the slider 84 and the plane 13a or plane 13b of the magnetic disk 13 becomes unstable, causing loss in reading and writing information by the slider 84. The HDD 10 of this embodiment has ten or more (for example, eleven) magnetic disks 13. As a result, each of the multiple magnetic disks 13 becomes thinner and more susceptible to displacement. However, the clamp 34 of this embodiment can improve rigidity and reduce the warping of the magnetic disk 13.
[0081] For example, as shown in Figure 3, the outer circumferential surface 51c of the clamp cylinder 51 can be expanded until the diameter of the outer circumferential surface 51c is approximately the same as the diameter of the inner circumferential surface 13c of the magnetic disk 13. Expanding the diameter of the outer circumferential surface 51c improves the rigidity of the clamp cylinder 51.
[0082] Furthermore, the retaining wall 52 is designed, for example, to hold a predetermined position on the magnetic disk 13. The retaining wall 52 extends from the outer peripheral surface 51c to the predetermined position. When the diameter of the outer peripheral surface 51c is expanded as in this embodiment, the distance between the outer peripheral surface 51c and the predetermined position on the magnetic disk 13 becomes shorter. That is, the length of the retaining wall 52 in the radial direction becomes shorter. As a result, the rigidity of the retaining wall 52 is improved.
[0083] As described above, the rigidity of the clamp 34 is improved, so even when fixed to the hub 32 by multiple screws 35, the clamp 34 is less likely to deform. In addition, the force with which the multiple screws 35 fix the clamp 34 to the hub 32 is transmitted more uniformly to the multiple magnetic disks 13. Consequently, the rotating multiple magnetic disks 13 are less likely to wobble.
[0084] Before the clamp 34 is attached to the hub 32, the uppermost magnetic disk 13U and uppermost spacer 14U are not supported by the hub 32. However, the uppermost magnetic disk 13U and uppermost spacer 14U can be positioned relative to the hub 32, for example, by a cylindrical jig. This prevents the uppermost magnetic disk 13U and uppermost spacer 14U from falling off the spindle motor 12.
[0085] In the first embodiment described above, the HDD 10 includes a housing 11, a spindle motor 12, a plurality of magnetic disks 13, and a plurality of spacers 14. The spindle motor 12 includes a hub 32 and a clamp 34. The hub 32 is housed in the housing 11 and is mounted to the housing 11 so as to be rotatable around the rotation axis Ax. The clamp 34 is attached to the hub 32. The plurality of magnetic disks 13 are arranged along the rotation axis Ax and are attached to the spindle motor 12. Each of the plurality of spacers 14 is located between two adjacent magnetic disks 13 and is attached to the spindle motor 12. Each of the plurality of magnetic disks 13 has an inner circumferential surface 13c facing the rotation axis Ax. Each of the plurality of spacers 14 has an inner circumferential surface 14c facing the rotation axis Ax. The hub 32 has a support wall 42 and an outer circumferential surface 41c. The support wall 42 supports the plurality of magnetic disks 13 and the plurality of spacers 14. The outer circumferential surface 41c extends from the support wall 42 in a first direction D1 along the rotation axis Ax, supporting the inner circumferential surface 13c of at least one of the plurality of magnetic disks 13 and supporting the inner circumferential surface 14c of at least one of the plurality of spacers 14. The clamp 34 has an outer circumferential surface 51c and a retaining wall 52, and holds the plurality of magnetic disks 13 and the plurality of spacers 14 between the support wall 42 and the retaining wall 52. The outer circumferential surface 51c supports the outer circumferential surface 51c of at least one of the plurality of spacers 14. The retaining wall 52 protrudes from the outer circumferential surface 51c. The upper end 41e of the outer circumferential surface 41c in the first direction D1 is closer to the support wall 42 than the upper end 14e of the inner circumferential surface 14c in the first direction D1 of the spacer 14 closest to the retaining wall 52.
[0086] If the outer circumferential surface 41c of the hub 32 supports the inner circumferential surfaces 13c of all the magnetic disks 13 and the inner circumferential surfaces 14c of all the spacers 14, then, for example, a part of the clamp 34 fits into a recess provided in the hub 32. In this case, the outer circumferential surface of the clamp 34 that fits into the recess is positioned radially inward from the outer circumferential surface 41c of the hub 32. That is, the diameter of the outer circumferential surface of the clamp 34 becomes smaller. Alternatively, the hub 32 may not have a recess, and the clamp 34 may be placed on the end of the hub 32 in the first direction D1. In this case, the clamp 34 will be formed thinner in the direction along the rotation axis Ax. However, in the HDD 10 of this embodiment, the outer circumferential surface 51c of the clamp 34 supports the inner circumferential surface 14c of the spacer 14, and therefore has approximately the same diameter as the inner circumferential surface 14c. That is, the diameter of the outer circumferential surface 51c of the clamp 34 is expanded to approximately the same size as the diameter of the inner circumferential surface 14c of the spacer 14. This allows the HDD 10 to improve the rigidity of the clamp 34. A clamp 34 with high rigidity can, for example, transmit the force of the screw 35 that attaches the clamp 34 to the hub 32 more uniformly to the magnetic disk 13, and can also suppress bending caused by the screw 35 and the magnetic disk 13. Therefore, the HDD 10 can suppress the magnetic disk 13 held by the clamp 34 from wobbling during rotation.
[0087] The clamp 34 has an inner circumferential surface 51d facing the axis of rotation Ax. The hub 32 has a fitting surface 43a that supports the inner circumferential surface 51d. As a result, the fitting surface 43a of the hub 32 restricts the clamp 34 from moving radially relative to the hub 32. In other words, the hub 32 can position the clamp 34.
[0088] In the first direction D1, the upper end 41e of the outer circumferential surface 41c is closer to the support wall 42 than the uppermost spacer 14U, which is the closest to the retaining wall 52 among the multiple spacers 14. That is, in the direction along the rotation axis Ax, the length (thickness) of the outer circumferential surface 51c of the clamp 34 is greater than or equal to the length (thickness) of the inner circumferential surface 14c of the spacer 14. As a result, the HDD 10 can improve the rigidity of the clamp 34.
[0089] The outer circumferential surface 51c supports the inner circumferential surface 13c of at least one of the multiple magnetic disks 13. As a result, the outer circumferential surface 51c of the clamp 34 has approximately the same diameter as the inner circumferential surface 13c of the magnetic disk 13, since it supports the inner circumferential surface 13c of the magnetic disk 13. In other words, the diameter of the outer circumferential surface 51c of the clamp 34 is expanded to approximately the same size as the diameter of the inner circumferential surface 13c of the magnetic disk 13. This allows the HDD 10 to improve the rigidity of the clamp 34.
[0090] In the first direction D1, the upper end 41e of the outer peripheral surface 41c is closer to the support wall 42 than the uppermost magnetic disk 13U, which is the closest to the retaining wall 52 among the multiple magnetic disks 13. That is, in the direction along the rotation axis Ax, the length (thickness) of the outer peripheral surface 51c of the clamp 34 is greater than the length (thickness) of the inner peripheral surface 13c of the magnetic disk 13. As a result, the HDD 10 can improve the rigidity of the clamp 34.
[0091] The inner circumferential surface 14c of the uppermost spacer 14U, which is closest to the retaining wall 52 among the multiple spacers 14, is supported by the outer circumferential surface 51c of the clamp 34. The inner circumferential surface 14c of the remaining lower spacers 14L among the multiple spacers 14 is supported by the outer circumferential surface 41c of the hub 32. This allows the outer circumferential surface 41c to position all of the multiple spacers 14 except the uppermost spacer 14U before the clamp 34 is attached to the hub 32. Therefore, the HDD 10 is easier to assemble.
[0092] The inner surface 13c of the uppermost magnetic disk 13U, which is closest to the retaining wall 52 among the multiple magnetic disks 13, is supported by the outer surface 51c of the clamp 34. The inner surface 13c of the remaining lower magnetic disks 13L among the multiple magnetic disks 13 is supported by the outer surface 41c of the hub 32. As a result, before the clamp 34 is attached to the hub 32, the outer surface 41c can position all magnetic disks 13 except the uppermost magnetic disk 13U. Therefore, the HDD 10 is easier to assemble compared to when not only the uppermost magnetic disk 13U but also the other magnetic disks 13 and at least one spacer 14 are not positioned.
[0093] (Second embodiment) A second embodiment will be described below with reference to Figure 4. In the following descriptions of multiple embodiments, components having the same function as those already described will be denoted by the same reference numerals as those previously described, and their descriptions may be omitted. Furthermore, multiple components denoted by the same reference numerals do not necessarily share all functions and properties, and may have different functions and properties depending on the embodiment.
[0094] Figure 4 is an exemplary cross-sectional view showing a portion of the HDD 10 near the clamp 34 according to the second embodiment. As shown in Figure 4, a recess 201 is provided on the end face 41a of the hub cylinder 41 in the second embodiment. The recess 201 is recessed from the end face 41a in a second direction D2. The recess 201 is, for example, a groove extending in the circumferential direction. Note that the recess 201 is not limited to this example.
[0095] The hub cylinder 41 of the second embodiment further has an inner circumferential surface 41d. The inner circumferential surface 41d is an example of a fourth inner circumferential surface. The inner circumferential surface 41d is located on the opposite side of the outer circumferential surface 41c. The inner circumferential surface 41d is formed in a cylindrical shape extending along the axis of rotation Ax and defines the recess 201. The inner circumferential surface 41d faces radially inward. That is, the inner circumferential surface 41d faces the axis of rotation Ax. The inner circumferential surface 41d may also face, for example, in an oblique direction. The diameter of the inner circumferential surface 41d is, for example, about 24.0 mm. The diameter of the inner circumferential surface 41d is not limited to this example.
[0096] The hub 32 of the second embodiment has a projection 205 instead of projection 43. The projection 205 protrudes from the hub cylinder 41 in a first direction D1 at a position closer to the axis of rotation Ax than the recess 201.
[0097] The clamp 34 of the second embodiment further has a protrusion 211. The protrusion 211 projects from the end face 51b of the clamp cylinder 51 in a second direction D2. The protrusion 211 is formed, for example, as an annular shape extending in the circumferential direction. Note that the protrusion 211 is not limited to this example.
[0098] The protrusion 211 has an outer circumferential surface 211a. The outer circumferential surface 211a is an example of a fourth outer circumferential surface. The outer circumferential surface 211a is a substantially cylindrical curved surface extending along the axis of rotation Ax. The outer circumferential surface 51c faces radially outward. The diameter of the outer circumferential surface 211a is, for example, approximately 23.5 mm. Note that the diameter of the outer circumferential surface 211a is not limited to this example.
[0099] The diameter of the outer circumferential surface 211a of the protrusion 211 is smaller than the diameter of the outer circumferential surface 51c of the clamp cylinder 51. Also, the diameter of the outer circumferential surface 211a of the protrusion 211 is smaller than the diameter of the inner circumferential surface 41d of the hub cylinder 41.
[0100] The protrusion 211 is fitted into the recess 201 of the hub cylinder 41. The outer circumferential surface 211a of the protrusion 211 contacts the inner circumferential surface 41d of the hub cylinder 41, at least partially. This allows the outer circumferential surface 211a to support the inner circumferential surface 41d and restrict the clamp 34 from moving radially relative to the hub 32. On the other hand, the projection 205 of the hub 32 is spaced apart from the inner circumferential surface 51d of the clamp cylinder 51.
[0101] In the second embodiment, the outer circumferential surface 41c of the hub cylinder 41 contacts not only the inner circumferential surface 14c of the lower spacer 14L, but also the inner circumferential surface 14c of the uppermost spacer 14U. That is, the inner circumferential surface 14c of the uppermost spacer 14U supports the outer circumferential surface 41c of the hub cylinder 41.
[0102] Furthermore, the inner circumferential surface 14c of the uppermost spacer 14U faces the outer circumferential surface 51c of the clamp cylinder 51. The inner circumferential surface 14c of the uppermost spacer 14U is capable of contacting the outer circumferential surface 51c of the clamp cylinder 51. That is, the inner circumferential surface 14c of the uppermost spacer 14U supports the outer circumferential surface 51c of the clamp cylinder 51. In the second embodiment, the inner circumferential surface 14c of the uppermost spacer 14U may be spaced apart from the outer circumferential surface 51c of the clamp cylinder 51.
[0103] In the HDD 10 of the second embodiment described above, the hub 32 has an inner circumferential surface 41d facing the rotation axis Ax. The clamp 34 has an outer circumferential surface 211a that supports the inner circumferential surface 41d. As a result, the inner circumferential surface 41d of the hub 32 restricts the clamp 34 from moving radially relative to the hub 32. In addition, the inner circumferential surface 14c of one of the multiple spacers 14 supports the outer circumferential surface 41c of the hub 32 and also supports the outer circumferential surface 51c of the clamp 34. As a result, this one spacer 14 restricts the clamp 34 from moving radially relative to the hub 32. In other words, the hub 32 and the spacers 14 can position the clamp 34.
[0104] (Third embodiment) A third embodiment will be described below with reference to Figure 5. Figure 5 is an exemplary cross-sectional view showing the vicinity of the clamp 34 of the HDD 10 according to the third embodiment. As shown in Figure 5, the HDD 10 of the third embodiment differs from the second embodiment in that the clamp 34 does not have a protrusion 211.
[0105] The clamp 34 can be manufactured more easily by omitting the protrusion 211. In the third embodiment as well, the inner circumferential surface 14c of one of the multiple spacers 14 supports the outer circumferential surface 41c of the hub 32 and the outer circumferential surface 51c of the clamp 34. This allows the spacer 14 to restrict the radial movement of the clamp 34 relative to the hub 32. In other words, the hub 32 and the spacers 14 can position the clamp 34.
[0106] (Fourth embodiment) The fourth embodiment will be described below with reference to Figure 6. Figure 6 is an exemplary cross-sectional view showing the vicinity of the clamp 34 of the HDD 10 according to the fourth embodiment. As shown in Figure 6, the HDD 10 of the fourth embodiment differs from the third embodiment in that the uppermost spacer 14U is located between the uppermost magnetic disk 13U and the retaining wall 52. That is, the uppermost spacer 14U is located between the clamp 34 and one of the multiple magnetic disks 13, and is closer to the retaining wall 52 than the multiple magnetic disks 13. The contact surface 52a of the retaining wall 52 contacts the plane 14a of the uppermost spacer 14U.
[0107] In the direction along the axis of rotation Ax, the distance between the planes 14a and 14b of the uppermost spacer 14U (thickness of the uppermost spacer 14U) is greater than the distance between the planes 14a and 14b of the lower spacer 14L (thickness of the lower spacer 14L). Note that the thicknesses of the uppermost spacer 14U and the lower spacer 14L are not limited to this example.
[0108] The upper end 41e of the outer circumferential surface 41c of the hub cylinder 41 is closer to the support wall 42 than the upper end 14e of the inner circumferential surface 14c of the uppermost spacer 14U. The outer circumferential surface 41c of the hub cylinder 41 contacts not only the inner circumferential surface 14c of the lower spacer 14L but also the inner circumferential surface 14c of the uppermost spacer 14U. In other words, the inner circumferential surface 14c of the uppermost spacer 14U supports the outer circumferential surface 41c of the hub cylinder 41.
[0109] Furthermore, the inner circumferential surface 14c of the uppermost spacer 14U contacts the outer circumferential surface 51c of the clamp cylinder 51. In other words, the inner circumferential surface 14c of the uppermost spacer 14U supports the outer circumferential surface 51c of the clamp cylinder 51.
[0110] The outer circumferential surface 41c of the hub cylinder 41 contacts not only the inner circumferential surface 13c of the lower magnetic disk 13L, but also the inner circumferential surface 13c of the uppermost magnetic disk 13U. In other words, the outer circumferential surface 41c of the hub cylinder 41 supports all of the inner circumferential surfaces 13c of the multiple magnetic disks 13.
[0111] In the HDD 10 of the fourth embodiment described above, the uppermost spacer 14U, which is closest to the retaining wall 52 among the multiple spacers 14, is closer to the retaining wall 52 than the multiple magnetic disks 13. This makes it easier in the design of the HDD 10 to position the uppermost magnetic disk 13U, which is closest to the retaining wall 52 among the multiple magnetic disks 13, at a desired position relative to the hub 32. For example, the HDD 10 can arrange the multiple magnetic disks 13 such that the outer peripheral surface 41c of the hub 32 supports the inner peripheral surfaces 13c of all the magnetic disks 13.
[0112] The outer circumferential surface 41c supports all of the inner circumferential surfaces 13c of the multiple magnetic disks 13. This allows the outer circumferential surface 41c to position all of the magnetic disks 13 before the clamp 34 is attached to the hub 32. Thus, the HDD 10 is easy to assemble.
[0113] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]
[0114] 10...Hard disk drive (HDD), 11...Enclosure, 12...Spindle motor, 13...Magnetic disk, 13c...Inner surface, 13U...Upper magnetic disk, 13L...Lower magnetic disk, 14...Spacer, 14c...Inner surface, 14e...Upper end, 14U...Upper spacer, 14L...Lower spacer, 32...Hub, 34...Clamp, 41c...Outer surface, 41d...Inner surface, 41e...Upper end, 42...Support wall, 51c...Outer surface, 51d...Inner surface, 52...Retaining wall, 211a...Outer surface, Ax...Rotation axis, D1...First direction.
Claims
1. The casing and A motor having a hub housed in the aforementioned housing and mounted to the housing so as to be rotatable about a rotation axis relative to the housing, and a clamp attached to the hub, A plurality of magnetic disks arranged along the rotation axis and attached to the motor, Each of the following is located between two adjacent magnetic disks or between the clamp and one of the magnetic disks, and is attached to the motor, It is equipped with, Each of the plurality of magnetic disks has a first inner surface facing the axis of rotation, Each of the aforementioned spacers has a second inner surface facing the axis of rotation, The hub has a support wall that supports the plurality of magnetic disks and the plurality of spacers, and a first outer surface that extends from the support wall in a direction along the axis of rotation, supports the first inner surface of at least one of the plurality of magnetic disks, and supports the second inner surface of at least one of the plurality of spacers. The clamp has a second outer surface that supports the second inner surface of at least one of the plurality of spacers, and a retaining wall that protrudes from the second outer surface, and holds the plurality of magnetic disks and the plurality of spacers between the support wall and the retaining wall. Magnetic disk drive.
2. The clamp has a third inner surface facing the axis of rotation, The hub has a third outer surface that supports the third inner surface, A magnetic disk device according to claim 1.
3. The hub has a fourth inner surface facing the axis of rotation, The clamp has a fourth outer surface that supports the fourth inner surface, A magnetic disk device according to claim 1.
4. One of the plurality of spacers has a second inner surface that supports the first outer surface and also supports the second outer surface. A magnetic disk device according to claim 1.
5. The end of the first outer surface in the extension direction is closer to the support wall than the one of the plurality of spacers that is closest to the retaining wall. A magnetic disk device according to claim 1.
6. The second outer surface supports at least one of the first inner surfaces of the plurality of magnetic disks. A magnetic disk device according to claim 1.
7. The end of the first outer peripheral surface in the extension direction is closer to the support wall than the one of the plurality of magnetic disks that is closest to the holding wall. A magnetic disk device according to claim 6.
8. Of the plurality of spacers, the one closest to the retaining wall is closer to the retaining wall than the plurality of magnetic disks, A magnetic disk device according to claim 1.
9. The first outer surface supports all of the first inner surfaces of the plurality of magnetic disks. A magnetic disk device according to claim 8.
10. Of the plurality of spacers, the second inner surface closest to the retaining wall is supported by the second outer surface, and the remaining second inner surfaces of the plurality of spacers are supported by the first outer surface. A magnetic disk device according to claim 1.
11. Of the plurality of magnetic disks, the first inner surface closest to the retaining wall is supported by the second outer surface, and the remaining first inner surfaces of the plurality of magnetic disks are supported by the first outer surface. A magnetic disk device according to claim 1.