Disk device

Abstract

To provide a disk device capable of mounting a larger damper on a cover.SOLUTION: A disk device according to an embodiment includes a base, a first cover, a second cover, and a damper. The base has a bottom surface, a side wall protruding from the bottom surface in a first direction, a supporting surface provided on the end portion of the side wall in the first direction, and a storage space in which a magnetic disk is disposed within the bottom surface and the side wall. The first cover is attached to the base to close the storage space. The second cover covers the first cover, is supported on the supporting surface, and is coupled to the base. The damper has a constraining layer disposed between the first cover and the second cover and a viscoelastic body interposed between the first cover and the constraining layer. The constraining layer has a thin portion provided along the supporting surface and a thick portion connected to the thin portion.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a disk device. [Background technology]

[0002] A disk device such as a hard disk drive (HDD) has a magnetic disk, a magnetic head that reads and writes information from and to the magnetic disk, and a housing that houses various components. In some types of disk devices, the housing has a base, a first cover that closes the space inside the base, and a second cover that covers the first cover.

[0003] The disk drive may further include a damper that damps vibrations by deformation of a viscoelastic body. The damper is attached to the first cover, for example, between the first cover and the second cover. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Pat. No. 5,214,549 Summary of the Invention [Problem to be solved by the invention]

[0005] The dimensions of a disk drive are restricted by various conditions, and in designing a disk drive, these restrictions can make it difficult to place a damper of a desired size between the first cover and the second cover.

[0006] One example of a problem to be solved by the present invention is to provide a disk drive in which a larger damper can be attached to the cover. [Means for solving the problem]

[0007] A disk device according to one embodiment includes a magnetic disk, a base, a first cover, a second cover, and a damper. The base has a bottom surface facing the magnetic disk, a side wall protruding from the bottom surface in a first direction and surrounding the magnetic disk, and a support surface provided at an end of the side wall in the first direction, and a storage space in which the magnetic disk is disposed is provided inside the bottom surface and the side wall. The first cover is attached to the base so as to close the storage space. The second cover covers the first cover, is supported by the support surface, and is coupled to the base. The damper includes a constraint layer located between the first cover and the second cover, and a viscoelastic body interposed between the first cover and the constraint layer. The constraint layer includes a thin portion provided along the support surface, and a thick portion connected to the thin portion and thicker than the thin portion in the first direction. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is an exemplary perspective view showing an HDD according to an embodiment. [Diagram 2] FIG. 2 is an exemplary cross-sectional view showing one end of the HDD of the embodiment. [Diagram 3] FIG. 3 is an exemplary cross-sectional view that illustrates the other end of the HDD of the above embodiment. [Figure 4] FIG. 4 is an exemplary perspective view showing the HDD of the above embodiment excluding the outer cover and the protector. [Diagram 5] FIG. 5 is an exemplary perspective view showing the HDD of the above embodiment excluding the inner cover, the outer cover, and the protector. [Figure 6] FIG. 6 is an exemplary plan view showing the magnets and constraint layers of the above embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] An embodiment will be described below with reference to FIGS. 1 to 6. In this specification, components according to the embodiment and their descriptions may be described in a number of ways. The components and their descriptions are merely examples and are not limited by the expressions in this specification. The components may be identified by names different from those in this specification. The components may also be described by expressions different from those in this specification.

[0010] In the following description, "inhibit" is defined as, for example, preventing the occurrence of an event, action, or effect, or reducing the magnitude of an event, action, or effect.

[0011] 1 is an exemplary perspective view showing a hard disk drive (HDD) 10 according to one embodiment. The HDD 10 is an example of a disk device, and may also be called an electronic device, a storage device, an external storage device, or a magnetic disk device. The HDD 10 has a housing 11 that houses various components.

[0012] As shown in each drawing, for convenience, an X-axis, a Y-axis, and a Z-axis are defined in this specification. The X-axis, the Y-axis, and the Z-axis are perpendicular to each other. The X-axis is provided along the width of the HDD 10. The Y-axis is provided along the length of the HDD 10. The Z-axis is provided along the thickness of the HDD 10.

[0013] Furthermore, in this specification, an X direction, a Y direction, and a Z direction are defined. The X direction is a direction along the X axis, and includes a +X direction indicated by an arrow on the X axis, and a -X direction opposite to the direction of the X axis arrow. The Y direction is a direction along the Y axis, and includes a +Y direction indicated by an arrow on the Y axis, and a -Y direction opposite to the direction of the Y axis arrow. The Z direction is a direction along the Z axis, and includes a +Z direction indicated by an arrow on the Z axis, and a -Z direction opposite to the direction of the Z axis arrow.

[0014] 2 is an exemplary cross-sectional view showing a schematic diagram of an end of the HDD 10 in the -Y direction in this embodiment. As shown in FIG. 2, the housing 11 has a base 15, an inner cover 16, an outer cover 17, and a protector 18. The inner cover 16 is an example of a first cover. The outer cover 17 is an example of a second cover. The protector 18 is an example of a third cover, and may also be called a protective cover.

[0015] 3 is an exemplary cross-sectional view showing an end of the HDD 10 in the +Y direction of the present embodiment. As shown in FIG. 3, the housing 11 further includes a protector 19. The protector 19 is also an example of a third cover. The housing 11 may omit the protectors 18 and 19.

[0016] The base 15 and the outer cover 17 are made of a metal such as an aluminum alloy. The inner cover 16, the protector 18, and the protector 19 are made of a metal such as a non-magnetic stainless steel. That is, the base 15, the inner cover 16, the outer cover 17, the protector 18, and the protector 19 are non-magnetic. However, the base 15, the inner cover 16, the outer cover 17, the protector 18, and the protector 19 may be made of other materials or may be ferromagnetic.

[0017] The base 15 is a bottomed container that opens in the +Z direction. As shown in Fig. 1, the base 15 extends in the Y direction. In other words, the length of the base 15 in the Y direction is longer than the length of the base 15 in the X direction and is also longer than the length of the base 15 in the Z direction.

[0018] Fig. 4 is an exemplary perspective view showing the HDD 10 of this embodiment excluding the outer cover 17 and the protectors 18 and 19. Fig. 5 is an exemplary perspective view showing the HDD 10 of this embodiment excluding the inner cover 16, the outer cover 17, and the protectors 18 and 19. As shown in Fig. 5, the base 15 has a bottom wall 21 and a side wall 22.

[0019] The bottom wall 21 is formed in a substantially rectangular (quadrilateral) plate shape extending along the XY plane. The bottom wall 21 has a bottom surface 21a. The bottom surface 21a faces substantially in the +Z direction as a whole. The bottom surface 21a may have projections and recesses.

[0020] The sidewall 22 protrudes from the bottom surface 21a in approximately the +Z direction. The +Z direction is an example of a first direction. The sidewall 22 is formed in a substantially rectangular frame shape. The bottom surface 21a and the frame-shaped sidewall 22 form (define, partition) a storage space S inside the base 15. In other words, the storage space S is provided inside the bottom surface 21a and the sidewall 22. The storage space S is open to the outside of the base 15 at an end of the base 15 in the +Z direction.

[0021] 2, the side wall 22 has an end surface 22a, a mounting surface 22b, an inner surface 22c, and an intermediate surface 22d. Note that the side wall 22 is not limited to this example. The end surface 22a is an example of a support surface.

[0022] The end surface 22a is provided at an end of the side wall 22 in the +Z direction. The end surface 22a is formed to be substantially flat and faces substantially in the +Z direction. The end surface 22a is formed in a substantially rectangular frame shape. In other words, the end surface 22a is formed in an endless shape.

[0023] As shown in FIG. 5, the end surface 22a has two short sides 22e, 22f and two long sides 22g, 22h. The short side 22e is located at an end of the base 15 in the -Y direction. The short side 22f is located at an end of the base 15 in the +Y direction. Each of the short sides 22e, 22f extends approximately in the X direction. The long side 22g is located at an end of the base 15 in the -X direction. The long side 22h is located at an end of the base 15 in the +X direction. Each of the long sides 22g, 22h extends approximately in the Y direction.

[0024] The mounting surface 22b is surrounded by the end surface 22a in a projection plane projected in the Z direction. The mounting surface 22b is located near the end surface 22a in the Z direction and is closer to the bottom surface 21a than the end surface 22a. In other words, the mounting surface 22b is recessed from the end surface 22a in approximately the -Z direction.

[0025] The mounting surface 22b is formed to be substantially flat and faces substantially in the +Z direction. The mounting surface 22b is formed in a substantially rectangular frame shape. However, the mounting surface 22b is not limited to this example. A plurality of screw holes 25 are provided in the mounting surface 22b.

[0026] The inner surface 22c is provided between the inner edge of the mounting surface 22b and the bottom surface 21a. The inner surface 22c faces the inside of the accommodation space S. The middle surface 22d is provided between the inner edge of the end surface 22a and the outer edge of the mounting surface 22b.

[0027] In other words, the side wall 22 has a rib 24 that protrudes from the mounting surface 22b in approximately the +Z direction. The rib 24 is formed in a substantially rectangular frame shape. The rib 24 has an end surface 22a and an intermediate surface 22d.

[0028] 4, the housing 11 further has a plurality of screws 26. The inner cover 16 is supported by, for example, the mounting surface 22b and attached to the mounting surface 22b by the screws 26. As a result, the inner cover 16 is attached to the base 15 so as to substantially air-tightly close the accommodation space S. For example, a gasket is provided between the inner cover 16 and the mounting surface 22b.

[0029] As shown in Fig. 2, the outer cover 17 covers the inner cover 16 via a gap G and is supported by the end surface 22a. In this embodiment, the edge of the outer cover 17 is joined to the end surface 22a by welding around the entire periphery. As a result, the outer cover 17 is joined to the base 15 so as to airtightly close the accommodation space S. In other words, the inner cover 16 and the outer cover 17 seal the accommodation space S. The housing 11 has a weld bead B where the outer cover 17 is welded to the base 15. The weld bead B is an example of a portion where the second cover is joined to the base.

[0030] The outer cover 17 may be coupled to other portions of the base 15. For example, the outer cover 17 may have a portion that surrounds the side wall 22 and be coupled to the side wall 22 at that portion. The outer cover 17 may also be coupled to the base 15 by other methods, such as by adhesive.

[0031] As shown in Fig. 4, a vent hole 27 is provided in the inner cover 16. Furthermore, as shown in Fig. 1, a vent hole 28 is provided in the outer cover 17. When assembling the HDD 10, air is evacuated from the storage space S through the vent holes 27, 28. Furthermore, the storage space S is filled with a gas other than air.

[0032] The gas filled in the accommodation space S is, for example, a low-density gas having a density lower than that of air, an inert gas having a low reactivity, etc. For example, helium is filled in the accommodation space S. Note that the accommodation space S may be filled with other fluids.

[0033] The ventilation hole 28 of the outer cover 17 is closed by a seal 29. The seal 29 air-tightly seals the ventilation hole 28, and prevents the gas filled in the storage space S from leaking out through the ventilation holes 27, 28.

[0034] Protector 18 is located at the end of housing 11 in the -Y direction. Protector 18 covers the end of side wall 22 in the -Y direction, the end of outer cover 17 in the -Y direction, and weld bead B. The -Y direction is a direction perpendicular to the +Z direction and is an example of the second direction.

[0035] The protector 19 is located at an end of the housing 11 in the +Y direction. The protector 19 covers an end of the side wall 22 in the +Y direction, an end of the outer cover 17 in the +Y direction, and the weld bead B.

[0036] 5, the HDD 10 further includes a plurality of magnetic disks 31, a spindle motor 32, a head stack assembly (HSA) 33, and a voice coil motor (VCM) 34. The VCM 34 is an example of an actuator.

[0037] The magnetic disk 31, the spindle motor 32, the HSA 33, and the VCM 34 are disposed in the accommodation space S. Therefore, the bottom surface 21a of the base 15 faces the magnetic disk 31, the spindle motor 32, the HSA 33, and the VCM 34. Furthermore, the sidewall 22 surrounds the magnetic disk 31, the spindle motor 32, the HSA 33, and the VCM 34.

[0038] The magnetic disk 31 is, for example, a recording medium having magnetic recording layers on its upper and lower surfaces. The diameter of the magnetic disk 31 is, for example, 3.5 inches. However, the magnetic disk 31 is not limited to this example.

[0039] The magnetic disks 31 are arranged along the XY plane. The multiple magnetic disks 31 are stacked at intervals in the Z direction. The HDD 10 of this embodiment has ten or more magnetic disks 31 arranged in the Z direction. Note that the number of magnetic disks 31 is not limited to this example.

[0040] The spindle motor 32 supports and rotates the multiple magnetic disks 31. The multiple magnetic disks 31 are held on a hub of the spindle motor 32 by, for example, clamp springs. The spindle motor 32 is attached to the bottom wall 21 of the base 15 and supported by the inner cover 16, for example.

[0041] The HSA 33 has a carriage 35 and a plurality of head gimbal assemblies (HGA) 36. The carriage 35 has an actuator block 41, a plurality of arms 42, and a holder 43.

[0042] For example, a support shaft 44 is provided at a position spaced apart from the magnetic disk 31 in a direction substantially perpendicular to the Z direction. The support shaft 44 extends from the bottom wall 21 in substantially the +Z direction, and is supported by the inner cover 16. The actuator block 41 is rotatably attached to the support shaft 44, for example, via a bearing.

[0043] The arms 42 protrude from the actuator block 41 in a direction substantially perpendicular to the Z direction. The arms 42 are arranged at intervals in the Z direction. Each of the arms 42 is formed in a plate shape that can enter between two adjacent ones of the magnetic disks 31. The holder 43 protrudes from the actuator block 41 in the opposite direction to the arms 42.

[0044] Each of the multiple HGAs 36 has a magnetic head 45 and a suspension 46. The magnetic head 45 may also be referred to as a slider. The magnetic head 45 records and reproduces information on the recording layer of the magnetic disk 31. In other words, the magnetic head 45 reads and writes information from and to the magnetic disk 31.

[0045] The suspension 46 includes, for example, a base plate, a load beam extending from the base plate, and a flexure attached to the base plate and the load beam. The flexure is a type of flexible printed circuit board (FPC).

[0046] The base plate is attached to the tip of the arm 42. The magnetic head 45 is mounted on the flexure. Thus, the magnetic head 45 is attached to the suspension 46. Furthermore, the suspension 46 is attached to the carriage 35.

[0047] The VCM 34 has a coil 51, a magnet 52, and a yoke 53. The coil 51 is held by a holder 43 of the carriage 35. The magnet 52 is, for example, a permanent magnet, and is attached to the base 15 via the yoke 53.

[0048] When the coil 51 is energized, the carriage 35 rotates around the support shaft 44 due to an electromagnetic force generated by the current in the coil 51 and the magnetic field of the magnet 52. In this manner, the VCM 34 rotates the carriage 35, and moves the magnetic head 45 attached to the carriage 35 via the suspension 46 to a desired position.

[0049] As shown in FIG. 4, the inner cover 16 has a central portion 61 and a peripheral portion 62. The central portion 61 is a part of the inner cover 16 formed in a substantially rectangular plate shape. The central portion 61 is provided with the ventilation hole 27 and supports the spindle motor 32 and the support shaft 44. The peripheral portion 62 is a part of the inner cover 16 formed in a substantially rectangular frame shape. The peripheral portion 62 surrounds the central portion 61. As shown in FIG. 2, the peripheral portion 62 is supported by the mounting surface 22b of the side wall 22 and attached to the mounting surface 22b by the screws 26.

[0050] In the Z direction, the thickness of the central portion 61 and the thickness of the peripheral portion 62 are approximately equal. The peripheral portion 62 is closer to the bottom surface 21a of the bottom wall 21 than the central portion 61. For example, the inner cover 16 is bent, for example, by press processing, so that the central portion 61 protrudes from the inner edge of the peripheral portion 62 approximately in the +Z direction.

[0051] 4, the central portion 61 has two mounting surfaces 61a, 61b and an inclined surface 61c. The mounting surfaces 61a, 61b are formed substantially flat and face substantially in the +Z direction. The mounting surfaces 61a, 61b face the outer cover 17 through the gap G between the inner cover 16 and the outer cover 17.

[0052] The mounting surface 61a is provided at the end of the central portion 61 in the -X and -Y directions. The magnet 52 of the VCM 34 overlaps the mounting surface 61a in the +Z direction. In other words, at least a portion of the mounting surface 61a is provided at a position spaced apart from or adjacent to the magnet 52 in the +Z direction. The mounting surface 61a may be provided at another position.

[0053] The mounting surface 61b is provided at an end of the central portion 61 in the +Y direction. The magnetic disk 31 overlaps the mounting surface 61b in the +Z direction. The mounting surface 61b may be provided at another position.

[0054] The inclined surface 61c is adjacent to the mounting surface 61b and faces the outer cover 17 via a gap G. In this embodiment, the inclined surface 61c is located around the spindle motor 32 and is continuous with the mounting surface 61b. The inclined surface 61c extends obliquely from the mounting surface 61b toward the outer cover 17.

[0055] As shown in FIG. 2, the outer cover 17 has a central portion 71 and a peripheral portion 72. The central portion 71 is a part of the outer cover 17 formed in a substantially rectangular plate shape. As shown in FIG. 1, the central portion 71 is provided with an air vent 28. The peripheral portion 72 is a part of the outer cover 17 formed in a substantially rectangular frame shape. The peripheral portion 72 surrounds the central portion 71. As shown in FIG. 2, the peripheral portion 72 is supported by an end surface 22a of the side wall 22 and is joined to the end surface 22a by welding.

[0056] In the Z direction, the thickness of the central portion 71 and the thickness of the peripheral portion 72 are approximately equal. The peripheral portion 72 is closer to the bottom surface 21a of the bottom wall 21 than the central portion 71. For example, the outer cover 17 is bent so that the central portion 71 protrudes from the inner edge of the peripheral portion 72 in approximately the +Z direction. Note that the peripheral portion 72 may extend obliquely from the central portion 71 toward the end surface 22a of the side wall 22.

[0057] The central portion 71 has an outer surface 71a and an inner surface 71b. The outer surface 71a is provided at an end of the outer cover 17 in the +Z direction. The outer surface 71a is formed substantially flat and faces substantially in the +Z direction. The inner surface 71b is located on the opposite side of the outer surface 71a. The inner surface 71b is formed substantially flat and faces substantially in the -Z direction. The inner surface 71b faces the central portion 61 of the inner cover 16 via the gap G.

[0058] The peripheral portion 72 has a concave surface 72a and an inner surface 72b. The concave surface 72a is connected to the outer surface 71a of the central portion 71 and faces approximately in the +Z direction as a whole. In this embodiment, the concave surface 72a is formed approximately flat at a position closer to the bottom surface 21a of the bottom wall 21 than the outer surface 71a, and faces approximately in the +Z direction.

[0059] 1, the concave surface 72a forms (defines, defines) two recesses 75, 76. The recess 75 is recessed from the outer surface 71a at the end of the outer cover 17 in the -Y direction. The recess 76 is recessed from the outer surface 71a at the end of the outer cover 17 in the +Y direction. The recesses 75, 76 extend approximately in the X direction and are provided across both ends of the outer cover 17 in the X direction.

[0060] 2, the inner surface 72b is located opposite to the concave surface 72a. The inner surface 72b is supported by the end surface 22a of the side wall 22. The inner surface 72b faces the central portion 61 and the peripheral portion 62 of the inner cover 16. The mounting surfaces 61a, 61b of the central portion 61 face the inner surface 71b of the central portion 71 and the inner surface 72b of the peripheral portion 72 of the outer cover 17, respectively.

[0061] The gap G between the inner cover 16 and the outer cover 17 has a wide gap GW and a narrow gap GN. The gap GW is a gap between the mounting surface 61a or 61b of the central portion 61 of the inner cover 16 and the inner surface 71b of the central portion 71 of the outer cover 17. The gap GN is a gap between the mounting surface 61a or 61b of the central portion 61 of the inner cover 16 and the inner surface 72b of the peripheral portion 72 of the outer cover 17.

[0062] In the Z direction (+Z direction), the distance between the mounting surface 61a or the mounting surface 61b and the inner surface 71b is greater than the distance between the mounting surface 61a or the mounting surface 61b and the inner surface 72b. Therefore, in the Z direction, the gap GW is wider than the gap GN. The gap GW and the gap GN are in communication with each other.

[0063] The protector 18 has an upper wall 81 and an end wall 82. The upper wall 81 is an example of a covering wall. The upper wall 81 is disposed in the recess 75 and extends substantially in the X direction along the recess 75. Therefore, the upper wall 81 covers the peripheral portion 72 of the outer cover 17.

[0064] The upper wall 81 has an upper surface 81a and an inner surface 81b. The upper surface 81a is formed to be approximately flat and faces approximately in the +Z direction. The inner surface 81b is located on the opposite side to the upper surface 81a. The inner surface 81b is formed to be approximately flat and faces approximately in the -Z direction. The inner surface 81b faces the concave surface 72a of the peripheral portion 72.

[0065] The inner surface 81b of the upper wall 81 is attached to the concave surface 72a of the peripheral portion 72 by, for example, an adhesive A1. The adhesive A1 is, for example, a synthetic adhesive. The adhesive A1 is not limited to this example and may be other substances capable of adhering multiple parts to each other, such as double-sided tape.

[0066] In the Z direction (+Z direction), the depth L1 of the recess 75 is equal to or greater than the sum L2 of the thickness of the upper wall 81 and the thickness of the adhesive A1. Therefore, the upper wall 81 does not protrude beyond the outer surface 71a of the central portion 71 to the outside of the recess 75. The depth L1 is, for example, the distance in the Z direction between the outer surface 71a and the portion of the recess 72a that is closest to the bottom surface 21a of the bottom wall 21. The sum of the thicknesses L2 is, for example, the distance in the Z direction between the upper surface 81a and the portion of the recess 72a to which the adhesive A1 is attached.

[0067] The end wall 82 extends in approximately the -Z direction from an end of the top wall 81 in the -Y direction. That is, the cross section of the protector 18 having the top wall 81 and the end wall 82 is formed in a approximately L-shape. The end wall 82 covers the side wall 22.

[0068] 3, the protector 19 has an upper wall 85 and an end wall 86. The upper wall 85 is an example of a covering wall. The upper wall 85 is disposed in the recess 76 and extends substantially in the X direction along the recess 76. Therefore, the upper wall 85 covers the peripheral portion 72 of the outer cover 17.

[0069] The upper wall 85 has an upper surface 85a and an inner surface 85b. The upper surface 85a is formed substantially flat and faces substantially in the +Z direction. The inner surface 85b is located opposite the upper surface 85a. The inner surface 85b is formed substantially flat and faces substantially in the -Z direction. The inner surface 85b faces the concave surface 72a of the peripheral portion 72. The inner surface 85b of the upper wall 85 is attached to the concave surface 72a of the peripheral portion 72 by, for example, an adhesive A2. The adhesive A2 is, for example, a synthetic adhesive.

[0070] In the Z direction (+Z direction), the depth of the recess 76 is equal to or greater than the sum of the thickness of the upper wall 85 and the thickness of the adhesive A2. Therefore, the upper wall 85 does not protrude beyond the outer surface 71a of the central portion 71 to the outside of the recess 75.

[0071] The end wall 86 extends in approximately the -Z direction from an end of the top wall 85 in the +Y direction. That is, the cross section of the protector 19 having the top wall 85 and the end wall 86 is formed in a approximately L-shape. The end wall 86 covers the side wall 22.

[0072] 4, the HDD 10 of this embodiment further includes two dampers 91 and 92. The dampers 91 and 92 are disposed in a gap G between the inner cover 16 and the outer cover 17.

[0073] 2, the damper 91 has a constrained layer 101 and a viscoelastic material (VEM) 102. Note that the damper 91 is not limited to this example. The constrained layer 101 may also be referred to as a vibration damping plate.

[0074] The constrained layer 101 is made of a metal such as ferromagnetic stainless steel. That is, the constrained layer 101 is a ferromagnetic body (magnetic material). The ferromagnetic stainless steel is, for example, SUS400 series stainless steel (ferritic stainless steel and martensitic stainless steel) in Japanese industrial standards (JIS). Specifically, the constrained layer 101 is made of SUS430. The constrained layer 101 may be made of another ferromagnetic material or may be a non-magnetic material.

[0075] The material of the inner cover 16 has a coefficient of thermal expansion closer to that of the material of the base 15 than the material of the constraining layer 101. That is, while both the inner cover 16 and the constraining layer 101 are made of stainless steel, the inner cover 16 is made of a type of stainless steel that has a coefficient of thermal expansion closer to that of the base 15.

[0076] The constraining layer 101 is located in the gap G between the inner cover 16 and the outer cover 17, and is formed in a plate shape arranged along the XY plane. The viscoelastic body 102 is interposed between the attachment surface 61a of the central portion 61 of the inner cover 16 and the constraining layer 101. In this way, the viscoelastic body 102 attaches the constraining layer 101 to the attachment surface 61a.

[0077] The constraining layer 101 has a plurality of portions having different thicknesses. In this embodiment, the constraining layer 101 has a thick portion 105 and a thin portion 106. The thick portion 105 and the thin portion 106 are integrally formed and connected to each other. In the Z direction (+Z direction), the thick portion 105 is thicker than the thin portion 106, and the thin portion 106 is thinner than the thick portion 105.

[0078] The thick portion 105 is located between the mounting surface 61a of the central portion 61 of the inner cover 16 and the inner surface 71b of the central portion 71 of the outer cover 17. That is, the thick portion 105 is located in the wide gap GW. The thick portion 105 has an upper surface 105a and an inner surface 105b.

[0079] The upper surface 105a is formed to be approximately flat and faces approximately in the +Z direction. The upper surface 105a faces the inner surface 71b of the central portion 71. The inner surface 105b is located on the opposite side of the upper surface 105a. The inner surface 105b is formed to be approximately flat and faces approximately in the -Z direction. The inner surface 105b faces the mounting surface 61a of the central portion 61.

[0080] 4, the thick portion 105 further has two edges 105c and 105d. The edges 105c and 105d may also be referred to as sides. The edge 105c is provided at an end of the thick portion 105 in the -Y direction and extends approximately in the X direction. The edge 105d is provided at an end of the thick portion 105 in the -X direction and extends approximately in the Y direction.

[0081] The edge 105c faces the portion of the rib 24 having the short side portion 22e and extends along the short side portion 22e. The edge 105d faces the portion of the rib 24 having the long side portion 22g and extends along the long side portion 22g.

[0082] The thin portion 106 is located between the end surface 22a of the side wall 22 and the thick portion 105. In other words, the thin portion 106 is located between the weld bead B and the thick portion 105. The thin portion 106 is provided along a portion of the end surface 22a of the side wall 22 that is close to the mounting surface 61a and the thick portion 105.

[0083] As shown in Fig. 2, the thin-walled portion 106 is located between the mounting surface 61a of the central portion 61 of the inner cover 16 and the inner surface 72b of the peripheral portion 72 of the outer cover 17. That is, the thin-walled portion 106 is located in the narrow gap GN. As shown in Fig. 4, the thin-walled portion 106 has a first thin-walled portion 107 and a second thin-walled portion 108.

[0084] The first thin portion 107 protrudes from the edge 105c of the thick portion 105 in approximately the -Y direction. Therefore, the first thin portion 107 is located between the end of the inner cover 16 in the -Y direction and the thick portion 105. The first thin portion 107 extends approximately in the X direction along the short side portion 22e. In other words, the first thin portion 107 extends approximately parallel to the short side portion 22e.

[0085] The second thin portion 108 protrudes substantially in the -X direction from the edge 105d of the thick portion 105. Therefore, the second thin portion 108 is located between the end of the inner cover 16 in the -X direction and the thick portion 105. The -X direction is a direction perpendicular to the +Z direction and perpendicular to the -Y direction, and is an example of a third direction.

[0086] The second thin portion 108 extends substantially in the Y direction along the long side portion 22g. In other words, the second thin portion 108 extends substantially parallel to the long side portion 22g. The end of the first thin portion 107 in the -X direction and the end of the second thin portion 108 in the -Y direction are connected to each other. Therefore, the thin portion 106 is formed substantially in an L shape.

[0087] The length (width) of the first thin portion 107 in the Y direction (-Y direction) is longer than the length (width) of the second thin portion 108 in the X direction (-X) direction. Note that the widths of the first thin portion 107 and the second thin portion 108 are not limited to this example.

[0088] 2, the first thin portion 107 of the thin portion 106 overlaps with the upper wall 81 of the protector 18 in the +Z direction. On the other hand, the thick portion 105 and the second thin portion 108 are spaced apart from the protector 18 in a direction perpendicular to the Z direction (+Z direction). In other words, the thick portion 105 and the second thin portion 108 do not overlap with the protector 18.

[0089] The thin portion 106 further has an upper surface 106a and an inner surface 106b. The first thin portion 107 and the second thin portion 108 each have a part of the upper surface 106a and a part of the inner surface 106b.

[0090] The upper surface 106a is formed substantially flat and faces substantially in the +Z direction. The upper surface 106a faces the inner surface 71b of the central portion 71 and the inner surface 72b of the peripheral portion 72. The upper surface 106a of the thin portion 106 is closer to the bottom surface 21a of the bottom wall 21 than the upper surface 105a of the thick portion 105.

[0091] The inner surface 106b is located on the opposite side to the upper surface 106a. The inner surface 106b is formed to be approximately flat and faces approximately in the -Z direction. The inner surface 106b faces the mounting surface 61a of the central portion 61. The inner surface 105b of the thick-walled portion 105 and the inner surface 106b of the thin-walled portion 106 form approximately the same plane and are continuous with each other.

[0092] The viscoelastic body 102 is interposed between the inner surface 105b of the thick portion 105 and the mounting surface 61a of the central portion 61 of the inner cover 16. Furthermore, the viscoelastic body 102 is interposed between the inner surface 106b of the thin portion 106 and the mounting surface 61a of the central portion 61 of the inner cover 16. That is, both the thick portion 105 and the thin portion 106 are attached to the mounting surface 61a by the viscoelastic body 102.

[0093] In the Z direction (+Z direction), the difference L3 between the thickness of the thick portion 105 and the thickness of the thin portion 106 is equal to or greater than the sum L2 of the thickness of the upper wall 81 and the thickness of the adhesive A1. The difference L3 in thickness is the distance in the Z direction between the upper surface 105a of the thick portion 105 and the upper surface 106a of the thin portion 106.

[0094] An adhesive A3 is applied to the inner surface 71b of the central portion 71 and the inner surface 72b of the peripheral portion 72 of the outer cover 17. The adhesive A3 is, for example, a double-sided tape. The adhesive A3 attaches the inner surface 71b of the central portion 71 to the upper surface 105a of the thick portion 105. Furthermore, the adhesive A3 attaches the inner surface 72b of the peripheral portion 72 to the upper surface 106a of the thin portion 106.

[0095] Fig. 6 is an exemplary plan view showing the magnet 52 and the constraining layer 101 of this embodiment. As shown in Fig. 6, the entire magnet 52 overlaps with the constraining layer 101 in the +Z direction. Note that a portion of the magnet 52 does not have to overlap with the constraining layer 101.

[0096] The magnet 52 has two magnetic poles 52a, 52b and a boundary 52c. The magnet 52 may have three or more magnetic poles. The two magnetic poles 52a, 52b are adjacent to each other in a direction perpendicular to the Z direction (+Z direction). The magnetic pole 52a is one of an N pole and an S pole, and the magnetic pole 52b is the other. The boundary 52c is the boundary between the two magnetic poles 52a, 52b.

[0097] In this embodiment, most of the magnetic poles 52a and 52b overlap the thick portion 105 in the +Z direction. Also, the entire boundary 52c overlaps the thick portion 105 in the +Z direction. Note that the magnetic poles 52a and 52b and a portion of the boundary 52c may overlap the thin portion 106, or may not overlap the constraining layer 101.

[0098] 3, the damper 92 has a constraining layer 111 and a viscoelastic body 112. Note that the damper 92 is not limited to this example. The constraining layer 111 is made of a metal such as ferromagnetic stainless steel, like the constraining layer 101 of the damper 91.

[0099] The constraining layer 111 is located in the gap G between the inner cover 16 and the outer cover 17, and is formed in a plate shape arranged along the XY plane. The viscoelastic body 112 is interposed between the attachment surface 61b of the central portion 61 of the inner cover 16 and the constraining layer 111. In this way, the viscoelastic body 112 attaches the constraining layer 111 to the attachment surface 61b.

[0100] The constraint layer 111 has a thick portion 115 and two thin portions 116 and 117. The thick portion 115 and the thin portions 116 and 117 are integrally formed and connected to each other. In the Z direction (+Z direction), the thick portion 115 is thicker than the thin portions 116 and 117.

[0101] The thick portion 115 is located between the mounting surface 61b of the central portion 61 of the inner cover 16 and the inner surface 71b of the central portion 71 of the outer cover 17. That is, the thick portion 115 is located in the wide gap GW. The thick portion 115 has an upper surface 115a and an inner surface 115b.

[0102] The upper surface 115a is formed to be approximately flat and faces approximately in the +Z direction. The upper surface 115a faces the inner surface 71b of the central portion 71. The inner surface 115b is located on the opposite side of the upper surface 115a. The inner surface 115b is formed to be approximately flat and faces approximately in the -Z direction. The inner surface 115b faces the mounting surface 61b of the central portion 61.

[0103] 4, the thick portion 115 further has an edge 115c. The edge 115c is provided at an end of the thick portion 115 in the +Y direction and extends substantially in the X direction. The edge 115c faces a portion of the rib 24 having the short side portion 22f and extends along the short side portion 22f.

[0104] The thin portion 116 is located between the end surface 22a of the side wall 22 and the thick portion 115. In other words, the thin portion 116 is located between the weld bead B and the thick portion 115. The thin portion 116 is provided along a portion of the end surface 22a of the side wall 22 that is close to the mounting surface 61b and the thick portion 115.

[0105] 3, the thin portion 116 is located between the attachment surface 61b of the central portion 61 of the inner cover 16 and the inner surface 72b of the peripheral portion 72 of the outer cover 17. That is, the thin portion 116 is located in the narrow gap GN.

[0106] The thin portion 116 protrudes from the edge 115c of the thick portion 115 in approximately the +Y direction. Therefore, the thin portion 116 is located between the end of the inner cover 16 in the +Y direction and the thick portion 115. The thin portion 116 extends approximately in the X direction along the short side portion 22f. In other words, the thin portion 116 extends approximately parallel to the short side portion 22f.

[0107] The thin portion 116 has an upper surface 116a and an inner surface 116b. The upper surface 116a is formed to be approximately flat and faces approximately in the +Z direction. The upper surface 116a faces the inner surface 71b of the central portion 71 and the inner surface 72b of the peripheral portion 72. The upper surface 116a of the thin portion 116 is closer to the bottom surface 21a of the bottom wall 21 than the upper surface 115a of the thick portion 115.

[0108] The inner surface 116b is located on the opposite side to the upper surface 116a. The inner surface 116b is formed to be approximately flat and faces approximately in the -Z direction. The inner surface 116b faces the mounting surface 61b of the central portion 61. The inner surface 115b of the thick-walled portion 115 and the inner surface 116b of the thin-walled portion 116 form approximately the same plane and are continuous with each other.

[0109] The thin portion 117 protrudes from the thick portion 115 toward the inclined surface 61c of the central portion 61 of the inner cover 16. The thick portion 115 is located between the thin portion 116 and the thin portion 117. The thin portion 117 may be omitted.

[0110] The thin portion 117 has an upper surface 117a and an inner surface 117b. The upper surface 117a is formed to be approximately flat and faces approximately in the +Z direction. The upper surface 117a faces the inner surface 71b of the central portion 71. The upper surface 115a of the thick portion 115 and the upper surface 117a of the thin portion 117 form approximately the same plane and are continuous with each other.

[0111] The inner surface 117b is located on the opposite side to the upper surface 117a. The inner surface 117b is formed substantially flat and faces substantially in the -Z direction. The inner surface 117b faces the inclined surface 61c of the central portion 61. The inner surface 117b of the thin portion 117 is farther away from the bottom surface 21a of the bottom wall 21 than the inner surface 115b of the thick portion 115.

[0112] The thin portion 116 overlaps the upper wall 85 of the protector 19 in the +Z direction. In the Z direction, the difference in thickness between the thick portion 115 and the thin portion 116 is equal to or greater than the sum of the thickness of the upper wall 85 and the thickness of the adhesive A2. On the other hand, the thick portion 115 and the thin portion 117 are spaced apart from the protector 19 in a direction perpendicular to the Z direction (+Z direction). In other words, the thick portion 115 and the thin portion 117 do not overlap the protector 19.

[0113] The inclined surface 61c of the central portion 61 of the inner cover 16 overlaps with the thin portion 117 in the +Z direction. On the other hand, the thick portion 115 and the thin portion 116 are spaced apart from the inclined surface 61c in a direction perpendicular to the Z direction (+Z direction).

[0114] The viscoelastic body 112 is interposed between the inner surface 115b of the thick portion 115 and the mounting surface 61b of the central portion 61 of the inner cover 16. Furthermore, the viscoelastic body 112 is interposed between the inner surface 116b of the thin portion 116 and the mounting surface 61b of the central portion 61 of the inner cover 16. That is, both the thick portion 115 and the thin portion 116 are attached to the mounting surface 61b by the viscoelastic body 112.

[0115] An adhesive A4 is applied to the inner surface 71b of the central portion 71 and the inner surface 72b of the peripheral portion 72 of the outer cover 17. The adhesive A4 is, for example, a double-sided tape. The adhesive A4 attaches the inner surface 71b of the central portion 71 to the upper surface 115a of the thick portion 115 and the upper surface 117a of the thin portion 117. Furthermore, the adhesive A4 attaches the inner surface 72b of the peripheral portion 72 to the upper surface 116a of the thin portion 116.

[0116] The magnetic disk 31 overlaps the constraining layer 111 in the +Z direction. On the other hand, the spindle motor 32 is separated from the constraining layer 111 in a direction intersecting the Z direction (+Z direction). Note that a portion of the magnetic disk 31 does not have to overlap the constraining layer 111.

[0117] The HDD 10 of this embodiment is mounted, for example, on a server rack of a server. The server rack, for example, mounts a plurality of HDDs 10 and cooling fans. Vibrations generated by other devices such as cooling fans may be transmitted to the HDD 10.

[0118] When vibrations are input to the HDD 10, the housing 11 vibrates, and the vibrations of the housing 11 are transmitted to the dampers 91, 92. This causes the constraining layers 101, 111 to vibrate relative to the housing 11. The viscoelastic bodies 102, 112 deform between the constraining layers 101, 111 and the inner cover 16, and convert the energy of the vibrations into heat. As a result, the dampers 91, 92 damp the vibrations of the housing 11.

[0119] The constraining layers 101, 111 are attached to the outer cover 17 by adhesives A3, A4. However, the outer cover 17 is thin and has lower rigidity than the constraining layers 101, 111. For this reason, the outer cover 17 deforms in response to the vibration of the constraining layers 101, 111. In other words, the constraining layers 101, 111 can vibrate relative to the housing 11 even when attached to the outer cover 17.

[0120] The damper 91 damps vibrations input to the housing 11 in the vicinity of the VCM 34. Therefore, the damper 91 can damp vibrations input to the HSA 33 in the vicinity of the VCM 34.

[0121] The damper 92 damps vibrations input to the housing 11 in the vicinity of the magnetic disk 31. Therefore, the damper 92 can damp vibrations input to the HSA 33 in the vicinity of the magnetic disk 31.

[0122] Since the dampers 91 and 92 damp the vibrations of the HSA 33, the HDD 10 can accurately position the magnetic head 45 even if the recording density is high. That is, the HDD 10 can improve the recording density.

[0123] In the technical field of HDDs, the Small Form Factor Committee has established, for example, SFF-8300, which is a form factor for 3.5-inch hard disk drives. SFF-8300 sets multiple maximum dimensions (hereinafter referred to as "prescribed dimensions") for the dimensions of HDDs in the Z direction.

[0124] In a hard disk drive filled with helium, for example, the outer cover is welded to the base to prevent the helium from leaking out. In addition, a protector protects the area where the base and the outer cover are welded. However, if a protector is attached to a flat outer cover, the HDD will exceed the specified dimensions or the internal space of the HDD will be reduced.

[0125] In this embodiment, the upper walls 81, 85 of the protectors 18, 19 are disposed in the recesses 75, 76. This allows the dimensions of the HDD 10 in the Z direction to conform to the specified dimensions, and also allows the storage space S to be formed larger in the Z direction.

[0126] On the other hand, by providing the recesses 75, 76 in the outer cover 17, a narrow gap GN is provided in the gap G between the inner cover 16 and the outer cover 17. Furthermore, if the number of magnetic disks 31 is large, the VCM 34 is enlarged in the Z direction. As the VCM 34 is enlarged, the gap GN becomes narrower at the position overlapping the VCM 34.

[0127] It is difficult to arrange a damper having a thick constraining layer in a small gap GN. However, the constraining layers 101, 111 of the present embodiment have thin portions 106, 116 that can be arranged in the gap GN. Therefore, the constraining layers 101, 111 can be arranged in the gap GN and can be formed wider along the inner cover 16.

[0128] Generally, the constraining layer is set to a predetermined mass so that the damper can effectively damp vibration. If the constraining layer is thin and light, the vibration damping effect of the damper may be reduced. However, the constraining layers 101, 111 of this embodiment have thick portions 105, 115 in the wide gap GW, so that the predetermined mass can be obtained.

[0129] As described above, in the HDD 10 of this embodiment, under dimensional constraints such as SFF-8300, the storage space S is set larger in the Z direction, and the constraining layers 101, 111 having a size capable of effectively attenuating vibrations can be disposed in the gap G. By setting the storage space S to be larger, the HDD 10 can, for example, increase the number of magnetic disks 31, and thus increase the storage capacity.

[0130] In the HDD 10 according to the first embodiment described above, the base 15 has a bottom surface 21a, a side wall 22, and an end surface 22a. The bottom surface 21a faces the magnetic disk 31. The side wall 22 protrudes from the bottom surface 21a in the +Z direction and surrounds the magnetic disk 31. The end surface 22a is provided at an end of the side wall 22 in the +Z direction. A storage space S in which the magnetic disk 31 is disposed is provided inside the bottom surface 21a and the side wall 22. The inner cover 16 is attached to the base 15 so as to close the storage space S. The outer cover 17 covers the inner cover 16, is supported by the end surface 22a, and is coupled to the base 15. The damper 91 has a constraining layer 101 located between the inner cover 16 and the outer cover 17, and a viscoelastic body 102 interposed between the inner cover 16 and the constraining layer 101. The constraining layer 101 has a thin portion 106 and a thick portion 105 connected to the thin portion 106. The thin portion 106 is provided along the end surface 22a. The thick portion 105 is thicker than the thin portion 106 in the +Z direction.

[0131] As described above, the thin-walled portion 106 is provided along the end surface 22a. The end surface 22a is formed in a frame shape because it is provided at the end of the side wall 22 surrounding the magnetic disk 31. That is, the thin-walled portion 106 is located near the outer edges of the base 15, the inner cover 16, and the outer cover 17. In general, the gap G (gap GN) between the outer edge of the inner cover 16 and the outer edge of the outer cover 17 is narrow. For example, a protector 18 is attached to the outer edge of the outer cover 17 to cover the weld bead B at which the base 15 and the outer cover 17 are joined. In this case, the peripheral portion 72 of the outer edge of the outer cover 17 is bent to approach the inner cover 16, and a recess 75 into which the protector 18 fits is provided so that the dimension of the HDD 10 in the +Z direction is set within a specified range defined in SFF-8300. In another example, the outer edge of the outer cover 17 is bent to approach the inner cover 16, and the outer edge of the outer cover 17 is recessed, so as to prevent the outer edge of the outer cover 17 located at the corner of the HDD 10 from colliding with other components when the HDD 10 is mounted on a server rack. In this embodiment, the thin-walled portion 106 of the constraining layer 101 is disposed near the outer edges of the inner cover 16 and the outer cover 17, so that the thin-walled portion 106 can be disposed in the narrow gap GN between the outer edge of the inner cover 16 and the outer edge of the outer cover 17. That is, the constraining layer 101 can be provided not only in the wide gap GW but also in the narrow gap GN between the outer edge of the inner cover 16 and the outer cover 17, and can be formed wider. On the other hand, the constraining layer 101 can be provided with the thick-walled portion 105 in the wide gap G (gap GW) between the inner cover 16 and the outer cover 17, which is spaced apart from the outer edge. As described above, the constraining layer 101 can be made larger and attached to the inner cover 16 under the dimensional constraints of the HDD 10 due to various conditions. Generally, the damper 91 can effectively damp vibrations if the constraining layer 101 is heavy. The constraining layer 101 of this embodiment is made heavier by being enlarged in width and thickness. Therefore, the HDD 10 of this embodiment can reduce vibrations and noise by the damper 91.

[0132] In other words, the base 15 has a bottom surface 21a and a side wall 22. The bottom surface 21a faces the magnetic disk 31. The side wall 22 protrudes from the bottom surface 21a in the +Z direction and surrounds the magnetic disk 31. An accommodation space S in which the magnetic disk 31 is arranged is provided inside the bottom surface 21a and the side wall 22. The inner cover 16 is attached to the base 15 so as to close the accommodation space S. The outer cover 17 covers the inner cover 16 and is connected to the base 15. The damper 91 has a constraining layer 101 located between the inner cover 16 and the outer cover 17, and a viscoelastic body 102 interposed between the inner cover 16 and the constraining layer 101. The constraining layer 101 has a thick portion 105 and a thin portion 106 connected to the thick portion 105. The thin portion 106 is located between the thick portion 105 and the weld bead B at which the base 15 and the outer cover 17 are joined, and is thinner than the thick portion 105 in the +Z direction.

[0133] As described above, the thin portion 106 is located between the weld bead B and the thick portion 105. That is, the thin portion 106 is located near the outer edges of the base 15, the inner cover 16, and the outer cover 17. In general, the gap GN between the outer edge of the inner cover 16 and the outer cover 17 is narrow. In this embodiment, the thin portion 106 of the constraining layer 101 is located near the outer edges of the inner cover 16 and the outer cover 17, so that the thin portion 106 can be located in the narrow gap GN between the outer edge of the inner cover 16 and the outer cover 17. That is, the constraining layer 101 can be provided not only in the wide gap GW but also in the narrow gap GN between the outer edge of the inner cover 16 and the outer cover 17, and can be formed wider. On the other hand, the constraining layer 101 can be provided with the thick portion 105 in the wide gap GW between the inner cover 16 and the outer cover 17, which is spaced apart from the outer edges. As described above, the constraining layer 101 can be made larger and attached to the inner cover 16 under various dimensional constraints of the HDD 10. Furthermore, the constraining layer 101 of this embodiment becomes heavier as it is made larger in width and thickness. Therefore, the HDD 10 of this embodiment can reduce vibration and noise by the damper 91.

[0134] The outer cover 17 is bonded to the end surface 22a. Therefore, the gap GN between the outer edge of the inner cover 16 and the outer cover 17 becomes narrow. However, in this embodiment, the thin portion 106 of the constraining layer 101 is disposed near the outer edges of the inner cover 16 and the outer cover 17, so that the thin portion 106 can be disposed in the narrow gap GN between the outer edge of the inner cover 16 and the outer cover 17. Therefore, in the HDD 10 of this embodiment, the constraining layer 101 can be enlarged under the dimensional constraints of the HDD 10 due to various conditions, and vibration and noise can be reduced by the damper 91.

[0135] The storage space S is filled with a gas other than air. For example, the storage space S is filled with helium. In this case, vibrations caused by the internal components of the HDD 10 are unlikely to affect the positioning of, for example, the magnetic head 45. On the other hand, vibrations input to the HDD 10 from the outside may affect the positioning of the magnetic head 45. However, the HDD 10 of this embodiment can attenuate the vibrations input from the outside by the damper 91, so that the magnetic head 45 can be positioned more precisely.

[0136] The protector 18 covers the weld bead B where the outer cover 17 is joined to the base 15. The thin portion 106 overlaps the protector 18 in the +Z direction. The thick portion 105 is spaced apart from the protector 18 in a direction perpendicular to the +Z direction. The protector 18 also overlaps the outer cover 17. For this reason, the outer edge of the outer cover 17 is bent closer to the inner cover 16, and a recess 75 into which the protector 18 fits is provided so that the dimensions of the HDD 10 in the +Z direction are set within a prescribed range defined in SFF-8300. As a result, for example, at a position spaced apart from the protector 18, the gap GW between the inner cover 16 and the outer cover 17 can be increased, or the storage space S can be increased. On the other hand, at the position where the protector 18 overlaps, the gap GN between the inner cover 16 and the outer cover 17 is narrowed. However, since the thin portion 106 is disposed in the narrow gap GN between the inner cover 16 and the outer cover 17, the constraining layer 101 can be formed wider. Also, since the thick portion 105 is spaced apart from the protector 18, it can be disposed in the wide gap GW between the inner cover 16 and the outer cover 17. Therefore, in the HDD 10 of this embodiment, the constraining layer 101 can be enlarged under the dimensional constraints of the HDD 10 due to various conditions, and vibration and noise can be reduced by the damper 91.

[0137] The protector 18 has an upper wall 81. The upper wall 81 covers the outer cover 17 and is attached to the outer cover 17 by an adhesive A1. The thin portion 106 overlaps the upper wall 81 in the +Z direction. In the +Z direction, the difference L3 between the thickness of the thick portion 105 and the thickness of the thin portion 106 is equal to or greater than the sum L2 of the thickness of the upper wall 81 and the thickness of the adhesive A1. The outer edge of the outer cover 17 is bent, for example, along the step between the thick portion 105 and the thin portion 106 to approach the inner cover 16, and a recess 75 into which the upper wall 81 of the protector 18 fits is provided. In this case, the depth L1 of the recess 75 in the +Z direction is generally approximately equal to the difference L3 between the thickness of the thick portion 105 and the thickness of the thin portion 106. For this reason, the sum L2 of the thicknesses of the upper wall 81 and the adhesive A1 that fit into the recess 75 is equal to or less than the depth L1 of the recess 75. Therefore, in the HDD 10 of this embodiment, the protector 18 can prevent the dimension of the HDD 10 in the +Z direction from exceeding one of the regulations defined in SFF-8300.

[0138] The protector 18 has an upper wall 81 that covers the outer cover 17 and is attached to the outer cover 17 with an adhesive A1. The thin portion 106 overlaps the upper wall 81 in the +Z direction. The outer cover 17 has an outer surface 71a provided at an end of the outer cover 17 in the +Z direction. The outer cover 17 is provided with a recess 75 that is recessed from the outer surface 71a and in which the upper wall 81 is disposed. In the +Z direction, the depth L1 of the recess 75 is equal to or greater than the sum L2 of the thickness of the upper wall 81 and the thickness of the adhesive A1. Therefore, in the HDD 10 of this embodiment, the protector 18 can prevent the dimension of the HDD 10 in the +Z direction from exceeding one of the regulations defined in SFF-8300.

[0139] The protector 18 covers the end of the outer cover 17 in the -Y direction perpendicular to the +Z direction. The thin portion 106 has a first thin portion 107 and a second thin portion 108. The first thin portion 107 is located between the end of the inner cover 16 in the -Y direction and the thick portion 105. The second thin portion 108 is located between the end of the inner cover 16 in the -X direction perpendicular to the +Z direction and perpendicular to the -Y direction and the thick portion 105. The first thin portion 107 overlaps the protector 18 in the +Z direction. The second thin portion 108 is spaced apart from the protector 18 in the direction perpendicular to the +Z direction. The length (width) of the first thin portion 107 in the -Y direction is longer than the length (width) of the second thin portion 108 in the -X direction. That is, the width of the first thin portion 107 that overlaps the protector 18 is wide, and the width of the second thin portion 108 that does not overlap the protector 18 is narrow. This allows the constraining layer 101 to set, for example, the width of the second thin portion 108 in the -X direction to a minimum and the width of the thick portion 105 in the -X direction to a maximum. Therefore, the constraining layer 101 can be made large in thickness.

[0140] The magnetic head 45 reads and writes information from and to the magnetic disk 31. The magnetic head 45 is attached to a suspension 46. The suspension 46 is attached to the carriage 35. The VCM 34 has a magnet 52 and is configured to rotate the carriage 35. The constraining layer 101 is a magnetic material. The magnet 52 overlaps the constraining layer 101 in the +Z direction. This allows the constraining layer 101 to shield the magnetic flux generated from the magnet 52, and prevents magnetic flux leaking from the HDD 10 from affecting other HDDs in, for example, a server rack.

[0141] The constraining layer 101 is made of ferromagnetic stainless steel. This makes the thin-walled portion 106 of the constraining layer 101 relatively heavy and rigid. Therefore, the damper 91 can effectively damp vibration.

[0142] The magnet 52 has two magnetic poles 52a and 52b and a boundary 52c between the two magnetic poles 52a and 52b. The boundary 52c overlaps with the thick portion 105 in the +Z direction. The magnetic flux at the boundary 52c between the two magnetic poles 52a and 52b has unique properties compared to the magnetic poles 52a and 52b. Therefore, leakage of magnetic flux may become large around the boundary 52c. However, the thick portion 105 can shield the magnetic flux more effectively than the thin portion 106. Therefore, the HDD 10 of this embodiment can more reliably block the magnetic flux leaking from the periphery of the boundary 52c.

[0143] The entire magnet 52 overlaps with the constrained layer 101 in the +Z direction. This allows the constrained layer 101 to more reliably shield the magnetic flux generated from the magnet 52, and suppress leakage of the magnetic flux from the HDD 10.

[0144] The base 15 and the outer cover 17 are made of an aluminum alloy, and the inner cover 16 is made of non-magnetic stainless steel, both of which are non-magnetic.

[0145] In general, the linear expansion coefficient of non-magnetic stainless steel is closer to that of aluminum alloy than that of magnetic stainless steel. By using non-magnetic stainless steel for inner cover 16, housing 11 is composed of base 15, inner cover 16, and outer cover 17, which have similar linear expansion coefficients, and the difference in the amount of thermal expansion and thermal contraction between each part of housing 11 when temperature changes can be suppressed. As a result, HDD 10 can suppress warping of housing 11 due to the difference in the amount of thermal expansion and thermal contraction between base 15 and inner cover 16, for example.

[0146] The viscoelastic body 102 is interposed between the thin portion 106 and the inner cover 16, and is also interposed between the thick portion 105 and the inner cover 16. That is, the viscoelastic body 102 is provided in a wider range between the constraining layer 101 and the inner cover 16. Therefore, the damper 91 can effectively damp vibrations.

[0147] The magnetic disk 31 overlaps the constraining layer 111 of the damper 92 in the +Z direction. The portion of the gap G between the inner cover 16 and the outer cover 17 that overlaps the magnetic disk 31 is wider than, for example, the portion that overlaps the VCM 34. For this reason, the constraining layer 111 of this embodiment becomes heavier due to its larger width and thickness. Therefore, the HDD 10 of this embodiment can reduce vibration and noise by the damper 92.

[0148] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0149] 10...hard disk drive (HDD), 15...base, 16...inner cover, 17...outer cover, 18, 19...protector, 21a...bottom surface, 22...side wall, 22a...end surface, 31...magnetic disk, 34...voice coil motor (VCM), 35...carriage, 45...magnetic head, 46...suspension, 52...magnet, 52a, 52b...magnetic pole, 52c...boundary, 81, 85...upper wall, 91, 92...damper, 101, 111...constraint layer, 102, 112...viscoelastic body, 105, 115...thick portion, 106, 116...thin portion, 107...first thin portion, 108...second thin portion, S...accommodating space, B...weld bead, A1, A2...adhesive.

Claims

1. A magnetic disk; a base having a bottom surface facing the magnetic disk, a side wall protruding from the bottom surface in a first direction and surrounding the magnetic disk, and a support surface provided at an end of the side wall in the first direction, the base having an accommodation space provided inside the bottom surface and the side wall in which the magnetic disk is placed; a first cover attached to the base so as to close the accommodation space; a second cover covering the first cover, supported by the support surface, and coupled to the base; a damper including a constraining layer located between the first cover and the second cover, and a viscoelastic body interposed between the first cover and the constraining layer; Equipped with the constraint layer has a thin portion provided along the support surface, and a thick portion connected to the thin portion and thicker than the thin portion in the first direction. Disk device.

2. The second cover is coupled to the support surface.

2. The disk device according to claim 1.

3. A magnetic disk; a base having a bottom surface facing the magnetic disk and a side wall protruding from the bottom surface in a first direction and surrounding the magnetic disk, the base having an accommodation space inside the bottom surface and the side wall in which the magnetic disk is disposed; a first cover attached to the base so as to close the accommodation space; a second cover covering the first cover and coupled to the base; a damper including a constraining layer located between the first cover and the second cover, and a viscoelastic body interposed between the first cover and the constraining layer; Equipped with the constraint layer has a thick portion and a thin portion located between the thick portion and a portion where the base and the second cover are joined, the thin portion being connected to the thick portion and being thinner than the thick portion in the first direction. Disk device.

4. The storage space is filled with a gas other than air.

4. The disk device according to claim 1 or 3.

5. a third cover covering a portion of the second cover joined to the base; Further comprising: the thin portion overlaps the third cover in the first direction, The thick portion is spaced apart from the third cover in a direction perpendicular to the first direction.

4. The disk device according to claim 1 or 3.

6. glue, Further comprising: the third cover has a cover wall that covers the second cover and is attached to the second cover by the adhesive; The thin portion overlaps the covering wall in the first direction, In the first direction, a difference between a thickness of the thick portion and a thickness of the thin portion is equal to or greater than a sum of a thickness of the covering wall and a thickness of the adhesive; 6. The disk device according to claim 5.

7. glue, Further comprising: the third cover has a cover wall that covers the second cover and is attached to the second cover by the adhesive; The thin portion overlaps the covering wall in the first direction, the second cover has an outer surface provided at an end of the second cover in the first direction, and a recess is provided that is recessed from the outer surface and in which the cover wall is disposed; In the first direction, the depth of the recess is equal to or greater than the sum of the thickness of the cover wall and the thickness of the adhesive; 6. The disk device according to claim 5.

8. the third cover covers an end of the second cover in a second direction perpendicular to the first direction; the thin portion has a first thin portion located between an end of the first cover and the thick portion in the second direction, and a second thin portion located between the end of the first cover and the thick portion in a third direction perpendicular to the first direction and perpendicular to the second direction, the first thin portion overlaps the third cover in the first direction; the second thin portion is spaced from the third cover in a direction perpendicular to the first direction, A length of the first thin portion in the second direction is longer than a length of the second thin portion in the third direction.

6. The disk device according to claim 5.

9. a magnetic head for reading and writing information from and to the magnetic disk; a suspension to which the magnetic head is attached; a carriage to which the suspension is attached; and an actuator having a magnet and configured to rotate the carriage; Further comprising: the constrained layer is a magnetic material, the magnet overlaps the constraining layer in the first direction; 4. The disk device according to claim 1 or 3.

10. The constrained layer is made of ferromagnetic stainless steel.

10. The disk device according to claim 9.

11. the magnet has two poles and a boundary between the two poles; the boundary overlaps the thick portion in the first direction; 10. The disk device according to claim 9.

12. The magnet entirely overlaps the constraining layer in the first direction.

10. The disk device according to claim 9.

13. The base and the second cover are made of a non-magnetic material.

10. The disk device according to claim 9.

14. The first cover is made of a non-magnetic material.

10. The disk device according to claim 9.

15. the viscoelastic body is interposed between the thin portion and the first cover, and is interposed between the thick portion and the first cover; 4. The disk device according to claim 1 or 3.

16. the magnetic disk overlaps the constraining layer in the first direction; 4. The disk device according to claim 1 or 3.

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