disc device

Abstract

Embodiments of the present application relate to a disk device. According to the embodiments, the disk device has an actuator assembly that supports a head, and a coil motor that rotates the actuator assembly about a support shaft extending in a first direction. The actuator assembly has an actuator block supported to the support shaft by a pair of bearings, a suspension assembly that mounts the head, a support frame that extends from the actuator block, and a first central axis that passes through the center between the pair of bearings and is orthogonal to the support shaft. The coil motor has a lower magnet and an upper magnet that face each other at intervals in the first direction, and a voice coil that is fixed to the support frame of the actuator assembly and is positioned between the lower magnet and the upper magnet. The thicknesses of the upper magnet and the lower magnet in the first direction are different from each other. The voice coil has a coil central axis that passes through the center in the first direction and extends parallel to the first central axis, and is disposed at a height position that is offset from the first central axis in the first direction.

Description

[0001] This application enjoys priority based on Japanese Patent Application No. 2025-000047 (filed on January 6, 2025). This application incorporates the entire contents of that basic application by reference. Technical Field

[0002] Embodiments of the present invention relate to a disk device. Background Technology

[0003] As a disk drive, for example, a hard disk drive (HDD) includes: a disk that is disposed within a housing and is capable of rotation; and an actuator assembly (sometimes called a head stack assembly (HSA)) that supports and rotates the read / write heads. Additionally, a voice coil motor (VCM) is disposed within the housing to rotate and position the actuator assembly.

[0004] The VCM includes: two magnets disposed on the upper and lower parts of the housing; and a voice coil fixed to the actuator assembly. The voice coil is configured to move freely between the two magnets.

[0005] Typically, the VCM, including the magnet and voice coil, is constructed and arranged symmetrically top to bottom. However, sometimes it is constructed asymmetrically to accommodate the configuration and layout of the HDD's components. For example, the thicknesses of the upper and lower magnets may differ.

[0006] However, when the VCM is asymmetrically configured, it generates vertical excitation forces on the voice coil, causing it to vibrate both upwards and downwards. This vibration is transmitted to the actuator assembly, producing pitch vibration in the actuator. The residual vibration caused by this pitch vibration can adversely affect the positioning accuracy of the magnetic head. Summary of the Invention

[0007] According to one embodiment, the disc device comprises: a housing including a base having a bottom wall and a cover facing the bottom wall; a disc-shaped recording medium rotatably disposed within the housing; a head for processing information on the recording medium; an actuator assembly including an actuator block, a suspension assembly, and a support frame, the actuator block being rotatably supported by a pair of bearings on a support shaft erected on the bottom wall and extending in a first direction, the suspension assembly extending from the actuator block in a direction intersecting the support shaft and mounting the head, the support frame extending from the actuator block; and a coil motor that rotates the actuator assembly. The coil motor comprises: a lower yoke disposed on the bottom wall; a lower magnet disposed on the lower yoke; an upper yoke spaced apart from the lower yoke in the first direction; an upper magnet disposed on the upper yoke and spaced apart from the lower magnet in the first direction; and a voice coil fixed to the support frame of the actuator assembly and located between the lower magnet and the upper magnet, the upper magnet and the lower magnet having different thicknesses in the first direction. The actuator assembly has a first central axis passing through the center between the pair of bearings and orthogonal to the support axis. The voice coil has a coil central axis extending through the center in the first direction and parallel to the first central axis, and is disposed at a height position offset from the first central axis in the first direction.

[0008] According to embodiments of the present invention, a disc device is provided that can suppress the generation of vibrations caused by a voice coil motor and improve positioning accuracy. Attached Figure Description

[0009] Figure 1 This is an exploded perspective view of the first embodiment of the hard disk drive (HDD) with the top cover removed.

[0010] Figure 2 This is a top view of the HDD.

[0011] Figure 3 This is a perspective view showing the rear side of the HDD.

[0012] Figure 4 This is a perspective view showing the actuator assembly and FPC unit of the HDD.

[0013] Figure 5 It is a cross-sectional view of the HDD, including the bearing portion of the actuator assembly of the HDD, the voice coil motor (VCM), and the spindle of the spindle motor.

[0014] Figure 6In the diagram, (a) is a perspective view showing the magnet and yoke of the VCM, and (b) is a schematic diagram showing the magnetization direction of the magnet.

[0015] Figure 7 This is a diagram showing the direction of the force acting on the voice coil of the VCM.

[0016] Figure 8 It is a diagram that schematically shows the relationship between the excitation component generated in the voice coil and the pitching torque.

[0017] Figure 9 It is a diagram schematically showing the relationship between other excitation components generated by the voice coil and the pitch torque.

[0018] Figure 10 This is a graph showing the analytical results of comparing the pitch torque of three HDDs with different coil heights.

[0019] Figure 11 This is a schematic top view of the actuator assembly and VCM in a state where the disk is rotated to the inner circumference.

[0020] Figure 12 This is a schematic top view of the actuator assembly and VCM in a state where the disk is rotated to the outer periphery.

[0021] Figure 13 It is a diagram that schematically shows the relationship between the overlap width of the voice coil and the magnet and the magnitude of the force Fx generated in the voice coil.

[0022] Figure 14 It is a cross-sectional view of the bearing portion, voice coil motor (VCM), and spindle motor of the actuator assembly of the HDD in the second embodiment.

[0023] Figure 15 It is a cross-sectional view of the bearing portion, voice coil motor (VCM), and spindle of the actuator assembly of the HDD according to the third embodiment.

[0024] Explanation of reference numerals in the attached figures

[0025] 10…House, 12…Base, 12a…Bottom wall, 12b…Side wall, 14…Cover, 17…Head, 18…Disk, 19…Spindle motor, 22…Actuator assembly, 24…Voice coil motor, 28…Bearing unit, 28a, 28b…Bearings, 29…Actuator block, 30…Suspension assembly, 31…Support shaft, 32…Arm, 33…Support frame, 34…Voice coil, 37a…Lower yoke, 37b…Upper yoke, 50…Printed circuit board, M1…Lower magnet, M2…Upper magnet, Ty1, Ty2…Pitch torque Detailed Implementation

[0026] Hereinafter, the disk device of the embodiment will be described with reference to the accompanying drawings.

[0027] Furthermore, the disclosure is always merely an example, and any appropriate modifications that can be readily conceived by those skilled in the art while maintaining the spirit of the invention are naturally included within the scope of this invention. Additionally, to make the description clearer, the drawings sometimes schematically represent the size, shape, etc., of various parts compared to the actual form, but this is always merely an example and does not constitute a limitation on the interpretation of the invention. Furthermore, in this specification and the drawings, for the same elements as those previously described with respect to existing figures, the same reference numerals are sometimes used, and detailed descriptions are appropriately omitted.

[0028] (First Embodiment)

[0029] As a disk device, the hard disk drive (HDD) of the first embodiment will be described in detail. Figure 1 This is an exploded perspective view of the HDD of the first embodiment, shown with the cover removed. Figure 2 This is a top view of the HDD after the cover has been removed.

[0030] like Figure 1 As shown, the HDD has a generally rectangular housing 10. The housing 10 has a rectangular box-shaped base 12 with an opening on its upper surface, and a cover (top cover) 14 that is threaded onto the base 12 by a plurality of screws 13 and closes the upper opening of the base 12. The base 12 has a rectangular bottom wall 12a facing the cover 14 with a gap, and side walls 12b that rise along the periphery of the bottom wall 12a, and is integrally formed, for example, by an aluminum alloy. The side walls 12b include a pair of long side walls facing each other and a pair of short side walls facing each other. The cover 14 is formed into a rectangular plate shape, for example, by stainless steel. The periphery of the cover 14 is threaded onto the upper surface of the side walls 12b by screws 13.

[0031] Inside the housing 10, there are multiple disks 18, for example, ten disks, which are disc-shaped recording media, and a spindle motor 19 that supports and rotates the disks 18. The spindle motor 19 is disposed on the bottom wall 12a. Each disk 18 is formed, for example, into a circular plate with a diameter of 96 mm (3.5 inches), having a substrate made of a non-magnetic material such as glass or aluminum, and magnetic recording layers formed on the upper surface (first surface) and lower surface (second surface) of the substrate. Each disk 18 is coaxially fitted with the hub of the spindle motor 19 and clamped by a clamping spring 20. Thus, the disk 18 is supported in a position parallel to the bottom wall 12a of the base 12. The multiple disks 18 are rotated at a predetermined speed by the spindle motor 19. Furthermore, the number of disks 18 mounted is not limited to 10, but may be 9 or less, or 11 or more.

[0032] like Figure 1 as well as Figure 2 As shown, within the housing 10, there are multiple magnetic heads 17 for recording and reproducing information on the disk 18, and an actuator assembly (sometimes called a head stack assembly (HSA)) 22 that supports these magnetic heads 17 movable relative to the disk 18. Additionally, within the housing 10, there is a voice coil motor (VCM) 24 that rotates and positions the actuator assembly 22; a ramp loading mechanism 25 that holds the magnetic heads 17 in an unloading position away from the disk 18 when they move to the outermost periphery of the disk 18; a baseboard unit (FPC unit) 21 that mounts electronic components such as a conversion connector; and a spoiler 70. The ramp loading mechanism 25 has a ramp 74 fixed to the base 12. Furthermore, the actuator assembly 22 and the VCM 24 constitute a head actuator.

[0033] Figure 3 This is a perspective view showing the back side of the HDD. As shown, a printed circuit board (sometimes called a control circuit board) 50 is disposed on the outer surface of the bottom wall 12a of the substrate 12 and is fastened to the bottom wall 12a by a plurality of screw threads. In this embodiment, the printed circuit board 50 is formed to be approximately one-third the size of the area of ​​the bottom wall 12a. The printed circuit board 50 is disposed in a shallow recess formed in the bottom wall 12a. The region of the printed circuit board 50 disposed in the bottom wall 12a opposite to the VCM 24 is located at a position offset from the region opposite to the disk 18. That is, the printed circuit board 50 does not overlap with the region opposite to the disk 18.

[0034] The printed circuit board 50 has an end edge located approximately aligned with one of the short sides (the short side separating from the disk 18) of the bottom wall 12a, and a pair of side edges extending approximately orthogonally to the end edge and located approximately aligned with a pair of long sides of the bottom wall 12a. The printed circuit board 50 has an outer surface exposed to the outside and an inner surface exposed on the opposite side. The printed circuit board 50 is mounted on the substrate 12 with its inner surface facing the bottom wall 12a.

[0035] On the inner surface of the printed circuit board 50, there are an interface connector 52 for connecting to external devices, a relay connector 54 for connecting to the connector on the side of the base 12, a connector terminal portion 55 for connecting to the spindle motor 19, and several other electronic components not shown. The printed circuit board 50 constitutes a control circuit board (control unit) that controls the operation of the spindle motor 19 and controls the operation of the VCM 24 and the magnetic head 17 via the FPC unit 21.

[0036] Interface connector 52 is mounted along the edge of printed circuit board 50. Relay connector 54 is electrically connected to substrate unit 21 via a relay connector (not shown) located on the bottom wall 12a side. Connector terminal portion 55 is connected to one end of connecting FPC 56 attached to the bottom wall 12a. The other end of connecting FPC 56 is electrically connected to spindle motor 19. Thus, printed circuit board 50 is electrically connected to substrate unit 21 and spindle motor 19.

[0037] Figure 4 This is a perspective view showing the actuator assembly and the base plate unit. As shown, the actuator assembly 22 includes: an actuator block 29 having a through hole 26; a bearing unit (unit bearing) 28 disposed within the through hole 26; a plurality of arms 32, for example 11, extending from the actuator block 29; a suspension assembly (sometimes called a head universal assembly: HGA) 30 mounted on each arm 32; and a magnetic head 17 supported on the suspension assembly 30. A support shaft (pivot) 31 is erected on the bottom wall 12a of the base 12. The support shaft 31 is erected substantially parallel to the rotation axis of the main spindle motor 19. That is, the support shaft 31 extends along the height direction Z (sometimes called the first direction) described later. The actuator block 29 is supported by the bearing unit 28 and is rotatable about the support shaft 31.

[0038] In this embodiment, the actuator block 29 and the 11 arms 32 are integrally formed from aluminum or the like, constituting a so-called E-block. The arms 32 are, for example, formed into elongated flat plates, extending from the actuator block 29 in a direction orthogonal to the support shaft 31. The 11 arms 32 are arranged parallel to each other with gaps between them.

[0039] The actuator assembly 22 has a bifurcated support frame 33 extending from the actuator block 29 in the opposite direction to the arm 32. The support frame 33 extends from the actuator block 29 in a direction orthogonal to the support shaft 31. The voice coil 34 is supported by the support frame 33. The voice coil 34 forms part of the VCM 24. The voice coil 34 is oriented with its extension around the central axis CF generally parallel to the support shaft 31.

[0040] like Figure 1 as well as Figure 2 As shown, the voice coil 34 is located between one of the pair of magnetic yokes 37a and 37b fixed on the base 12, and together with the permanent magnets fixed to these magnetic yokes 37a and 37b, it constitutes the VCM24.

[0041] like Figure 4As shown, the actuator assembly 22 includes 20 suspension assemblies 30 that each support a magnetic head 17. The suspension assemblies 30 are mounted on the extension ends 32a of each arm 32. The plurality of suspension assemblies 30 includes an upward head suspension assembly that supports the magnetic head 17 upwards, and a downward head suspension assembly that supports the magnetic head 17 downwards. These upward head suspension assemblies and downward head suspension assemblies are configured by changing the vertical orientation of suspension assemblies 30 of the same construction.

[0042] In this embodiment, Figure 4 In the middle, a downward head suspension assembly 30 is installed on the uppermost arm 32, and an upward head suspension assembly 30 is installed on the lowermost arm 32. Each of the nine middle arms 32 is equipped with both an upward head suspension assembly 30 and a downward head suspension assembly 30.

[0043] The suspension assembly 30 has a generally rectangular base plate 38, a load beam 42 composed of slender leaf springs, and a slender strip-shaped flexible member (wiring member) 40. The flexible member 40 has a freely movable gimbal portion on which a magnetic head 17 is mounted. The base end of the base plate 38 is fixed to the extension end 32a of the arm 32. The load beam 42 extends from the base plate 38 and tapers towards the front end as it extends. The base plate 38 and the load beam 42 are, for example, made of stainless steel. A tab 44 protrudes from the front end of the load beam 42. The tab 44 can engage with the aforementioned ramp 74, together with the ramp 74 forming a ramp loading mechanism 25.

[0044] like Figure 4 As shown, the FPC unit 21 integrally comprises a generally rectangular base portion 21a bent in an L-shape, an elongated strip-shaped relay portion 21b extending from one side edge of the base portion 21a, and a connecting portion 21c continuously disposed with the front end of the relay portion 21b. The base portion 21a, the relay portion 21b, and the connecting portion 21c are formed of a flexible printed wiring substrate (FPC). The flexible printed wiring substrate has: an insulating layer such as polyimide; a conductive layer formed on the insulating layer and having multiple wirings and connecting pads; and a protective layer covering the conductive layer.

[0045] Electronic components, such as a converter connector (not shown) and multiple capacitors, are mounted on the base portion 21a and electrically connected to wiring (not shown). A relay portion 21b extends from the side edge of the base portion 21a toward the actuator block 29 of the actuator assembly 22. A connecting portion 21c, located at the extended end of the relay portion 21b, is attached to the mounting surface of the actuator block 29 and is threadedly secured to the mounting surface by a fixing screw 72. A plurality of connection pads are provided in the connecting portion 21c. For example, a head IC (headamplifier) ​​67 is mounted in the connecting portion 21c, and this head IC 67 is connected to the connection pads and the base portion 21a via wiring. Furthermore, a voice coil 34 is connected to the connecting portion 21c.

[0046] Each suspension assembly 30 has a flexible element 40 having: one end electrically connected to the magnetic head 17; another end extending through a groove formed on the side edge of the arm 32 to the actuator block 29; and a connecting end (tail-end connecting terminal portion) 48c provided at the other end. The connecting end 48c is formed into an elongated rectangular shape. A plurality of connecting terminals (connecting pads) 45 are provided on the connecting end 48c. These connecting terminals 45 are respectively connected to the wiring of the flexible element 40. That is, the plurality of wirings of the flexible element 40 extend across approximately the entire length of the flexible element 40, with one end electrically connected to the magnetic head 17 and the other end connected to the connecting terminal (connecting pad) 45.

[0047] The connection terminal 45 located at the connection end 48c engages with the connection pad of the junction 21c, and is electrically connected to the wiring of the junction 21c via the connection pad. Thus, the 20 magnetic heads 17 of the actuator assembly 22 are electrically connected to the base part 21a via the wiring of the flexible member 40, the connection end 48c, the junction 21c of the FPC unit 21, and the relay part 21b.

[0048] Figure 5 It is a cross-sectional view of the HDD of the spindle, including the bearing section of the actuator assembly, the voice coil motor (VCM), and the spindle motor.

[0049] like Figure 5 As shown, the support shaft 31 of the actuator assembly 22 is erected on the inner surface of the bottom wall 12a and extends in the Z direction perpendicular to the bottom wall 12a. The support shaft 31 is inserted into the through hole 26 of the actuator block 29. The actuator block 29 is supported by the bearing unit 28 and can rotate freely about the support shaft 31.

[0050] The bearing unit 28 has a plurality of bearings, for example, two bearings 28a and 28b. Bearing 28a is fitted to the end of the support shaft 31 on the cover 14 side. Bearing 28b is fitted to the end of the support shaft 31 on the bottom wall 12a side. The two bearings 28a and 28b are arranged at a predetermined interval. The center CZ in the height direction Z between bearings 28a and bearing 28b is the center in the height direction of actuator assembly 22. When the axis passing through this center CZ and extending in a direction orthogonal to the Z direction is designated as the central axis (sometimes called the first central axis) C1, this central axis C1 extends through one of the 11 arms 32 located at the center in the height direction Z.

[0051] The support frame 33 of the actuator assembly 22 extends in a direction orthogonal to the height direction Z. The voice coil 34, supported by the support frame 33, is configured such that its winding center axis CF is parallel to the support shaft 31. Furthermore, according to this embodiment, when the line extending through the center of the voice coil 34 in the height direction Z (thickness direction) and in a direction orthogonal to Z is designated as the center axis (sometimes called the coil center axis) C2, the voice coil 34 and the support frame 33 are configured such that the center axis C2 of the voice coil 34 is located at a height offset by ΔZ relative to the center axis C1 of the actuator assembly 22 in the height direction Z. The center axis C2 of the voice coil 34 is located at a position offset by ΔZ upwards (towards the cover 14) relative to the center axis C1 of the actuator assembly.

[0052] like Figure 5 As shown, the spindle motor 19 includes: a pivot (spindle) 60 erected substantially vertically on the bottom wall 12a; a cylindrical rotating shaft 62 supported so as to be rotatable about the pivot 60; a substantially cylindrical hub 64 coaxially fixed around the rotating shaft 62; a stator coil SC fixed to the bottom wall 12a and disposed around the rotating shaft 62; and a cylindrical magnet (not shown) mounted on the inner circumferential surface of the hub 64 and facing the stator coil SC. The hub 64 has an outer circumferential surface located coaxially with the pivot 60; and an annular flange 65 integrally formed at the lower end (end on the bottom wall 12a side) of the outer circumferential surface.

[0053] The disk 18 is engaged with the outer peripheral surface of the hub 64 with its inner hole inserted through it. An annular spacer ring 66 is fitted onto the outer peripheral surface of the hub 64 and sandwiched between two adjacent disks 18. Multiple disks 18 and multiple spacer rings 66 are sequentially arranged on the flange 65 of the hub 64, mounted in an alternating overlapping manner. A disc-shaped clamping spring 20 is mounted on the upper end of the hub 64. The clamping spring 20 presses the inner peripheral portions of the multiple disks 18 and the spacer rings 66 towards the flange 65. Thus, the multiple disks 18 are fixed in a stacked state, spaced apart from each other by a predetermined interval. Ten disks 18 are supported so that they can rotate integrally with the rotation shaft 62 and the hub 64. The ten disks 18 are supported parallel to each other at predetermined intervals and substantially parallel to the bottom wall 12a.

[0054] Figure 6 In the diagram, (a) is a three-dimensional view showing the permanent magnet and yoke of the VCM, and (b) is a schematic diagram showing the magnetization direction of the permanent magnet.

[0055] like Figure 1 , Figure 5 , Figure 6 As shown in (a), VCM24 has: a lower yoke 37a and an upper yoke 37b disposed on the bottom wall 12a of the base 12; and a lower magnet M1 and an upper magnet M2 fixed to these yokes.

[0056] As mentioned above, the printed circuit board 50 is located in the area opposite to the VCM24, which affects the mounting space of the VCM24 in the height direction Z.

[0057] The lower magnetic yoke 37a is composed of a generally arc-shaped flat plate. The lower magnetic yoke 37a is disposed on the bottom wall 12a and fixed to the bottom wall 12a. The lower magnetic yoke 37a is disposed along the corner of the bottom wall 12a.

[0058] The upper yoke 37b has a flat plate having a shape substantially the same as the lower yoke 37a, and a pair of legs extending from both ends of the flat plate. The upper yoke 37b is arranged overlapping the lower yoke 37a in a state where the pair of legs abut against the lower yoke 37a. Furthermore, the upper yoke 37b and the lower yoke 37a are fixed to the bottom wall 12a by two fixing screws 40a and 40b. The upper yoke 37b faces the lower yoke 37a with a predetermined gap in the height direction Z.

[0059] In one example, a lower magnet M1 is fixed to the upper surface of the lower yoke 37a, and an upper magnet M2 is disposed on the lower surface of the upper yoke 37b. The lower magnet M1 and the upper magnet M2 are parallel to each other and face each other at a predetermined interval.

[0060] The lower magnet M1 is divided into two magnetization regions, M1a and M1b, at the center of its circumference. For example... Figure 6 As shown in (b), the lower magnet M1 is magnetized in such a way that the magnetization direction of the magnetization region M1a is opposite to that of the magnetization direction of the magnetization region M1b in the height direction (thickness direction) Z.

[0061] The upper magnet M2 is divided into two magnetization regions, M2a and M2b, at the center of its circumference. For example... Figure 6 As shown in (b), the upper magnet M2 is magnetized such that the magnetization direction of magnetization region M2a is opposite to that of magnetization region M2b in the height direction (thickness direction) Z. Except for thickness, the magnetization regions M2a and M2b of the upper magnet M2 have the same shape as the magnetization regions M1a and M1b of the lower magnet M1, and are located opposite to magnetization regions M1a and M1b, respectively.

[0062] like Figure 5 As shown, according to this embodiment, the thickness d1 of the lower magnet M1 in the height direction Z is different from the thickness d2 of the upper magnet M2 in the height direction Z. In one example, the upper magnet M2 is thicker than the lower magnet M1, and is set as d1 < d2. For example, d1 is 3.3 mm and d2 is 4.3 mm.

[0063] The voice coil 34, supported by the actuator assembly 22, is located between the lower magnet M1 and the upper magnet M2, and faces the lower magnet M1 and the upper magnet M2. The voice coil 34 moves circumferentially between the lower magnet M1 and the upper magnet M2 by the rotation of the actuator assembly 22 around the support shaft 31.

[0064] As previously described, the voice coil 34 is configured such that its central axis C2 is offset by ΔZ in the height direction Z relative to the central axis C1 of the actuator assembly 22. In this embodiment, the voice coil 34 is located offset by ΔZ relative to the central axis C1 of the actuator assembly 22 towards the thicker magnet, i.e., the upper magnet M2. Therefore, the central axis C2 of the voice coil 34 is centered in the height direction Z of the distance between the lower magnet M1 and the upper magnet M2.

[0065] In an HDD configured as described above, when a drive current flows through the voice coil 34 of VCM24, a circumferential force is generated by the interaction with the magnetic fields generated from the lower magnet M1 and the upper magnet M2, causing the actuator assembly 22 and the voice coil 34 to rotate together around the support shaft 31.

[0066] Figure 7 This is a schematic diagram showing the force acting on the voice coil 34 during driving.

[0067] To discuss the force and torque generated in voice coil 34, Figure 7A coordinate system is defined. The center between bearings 28a and 28b is set as the origin CZ. The direction parallel to the length axis of the voice coil is set as the X-axis, the height direction is set as the Z-axis, and the lateral direction orthogonal to both is set as the Y-axis. In the resultant force generated by the voice coil, Fy is the thrust used to make the actuator assembly 22 rotate about the support axis. In contrast, Fx and Fz do not contribute to the rotational performance of the actuator assembly 22, and Fz becomes the excitation force in the height direction Z (vertical direction).

[0068] like Figure 7 As shown, when the voice coil 34 is energized, a resultant force Fx is generated in the length direction (axial direction) X and a resultant force Fy in the Y direction, which is orthogonal to the length direction X, as the resultant force in the coil plane direction. Furthermore, when the lower magnet M1 and the upper magnet M2 are formed asymmetrically, for example, when one magnet is thicker than the other, an out-of-plane excitation force is generated in the voice coil 34, in this case, an excitation force Fz in the Z direction. This out-of-plane excitation force Fz is the main reason for the pitch torque generated in the actuator assembly 22.

[0069] Therefore, according to this embodiment, as previously described, the voice coil 34 is configured such that its central axis C2 is located at a position offset by ΔZ in the Z direction relative to the central axis C1 of the actuator assembly 22, i.e., the central axis C1 passing through the center between the bearings 28a and 28b.

[0070] Figure 8 This is a diagram schematically showing the relationship between the excitation force Fz generated in the height direction Z by the voice coil and the pitch torque. Figure 9 It is a diagram schematically showing the relationship between the resultant force Fx in the length direction X generated by the voice coil and the pitch torque.

[0071] like Figure 8 As shown, when the excitation force in the height direction Z is set as Fz and the distance between the center position of the distributed force constituting Fz and the center CZ between bearings 28a and 28b is set as r1, the pitch torque Ty1 of the actuator assembly 22 about the Y-axis (the axis that passes through the center CZ and is orthogonal to the length direction X) caused by the excitation force Fz becomes Ty1 = Fz × r1.

[0072] like Figure 9 As shown, when the resultant force in the length direction X is set as Fx and the offset in the height direction Z of the central axis C2 of the voice coil 34 is set as ΔZ, the pitch torque Ty2 of the actuator assembly 22 about the Y-axis caused by the resultant force Fx becomes Ty2=Fx×ΔZ.

[0073] When the height of the central axis C2 of the voice coil 34 is the same as the height of the center CZ between the bearings, FX is only a translational force. However, when there is a height offset ΔZ, a torque is generated due to Fx, resulting in a pitching torque Ty2.

[0074] In this embodiment, the generating force and altitude offset ΔZ of VCM24 are adjusted so that the two pitch torques Ty1 and Ty2 cancel each other out. Regarding the pitch torque Ty1, the absolute value of the torque is large at the inner and outer circumference positions of the disk. Therefore, it is preferable to reduce the pitch torque at the inner or outer circumference positions of the disk.

[0075] In this embodiment, ΔZ is adjusted so that the two pitch torques Ty1 and Ty2 are approximately the same in magnitude and opposite in direction, so that torque cancellation is generated at the inner circumference of the disk.

[0076] Figure 10 The figure shows the variation of pitch torque for three different examples of the height offset ΔZ of the voice coil 34.

[0077] Figure 10 (a) shows the analytical results of the pitch torque when the height offset ΔZ = 0 for the voice coil 34. When the height offset is zero, the resultant force Fx in the length direction X is only a translational force, and therefore does not produce a pitch torque Ty2. It can be seen that at the outer and inner circumferences of the disk, only the pitch torque Ty1 caused by the excitation force Fz in the height direction Z is generated.

[0078] Figure 10 (b) shows the analytical results of the pitch torque when the voice coil 34 is offset by a height deviation ΔZ = 3 mm towards the cover side. In this case, the pitch torques Ty1 and Ty2 are generated with approximately the same magnitude but opposite directions at both the outer and inner circumference sides of the disk. Therefore, it can be concluded that the pitch torques Ty1 and Ty2 cancel each other out, and the pitch torque (Ty1 + Ty2) is approximately zero at any coil position.

[0079] Figure 10 (c) shows the analytical results of the pitch torque when the voice coil 34 is offset by a height deviation ΔZ = -3 mm, that is, offset by 3 mm towards the base. In this case, it can be seen that pitch torques Ty1 and Ty2 of approximately the same magnitude and direction are generated at the outer and inner circumferences of the disk, resulting in an increase in the pitch torque (Ty1 + Ty2).

[0080] It can be seen that if the direction of the height offset ΔZ is different, the pitch torque will increase. That is, it can be seen that when using lower magnet M1 and upper magnet M2 with different thicknesses in VCM24, it is preferable that the height offset direction of the central axis C2 of the voice coil 34 relative to the central axis C1 between the bearings is towards the side of the upper magnet M2, which has a thicker thickness.

[0081] As described above, according to the HDD of this embodiment, by maximally increasing the thickness of the upper magnet M2 of VCM24, the free space on VCM24 inside the housing can be effectively utilized, thereby increasing the thrust torque of VCM24.

[0082] Additionally, as previously described, the voice coil 34 and the support frame 33 are configured such that the central axis C2 of the voice coil 34 is located at a height position offset by ΔZ in the height direction Z relative to the central axis C1 of the actuator assembly 22 (the axis passing through the center CZ between bearings 28a and 28b and orthogonal to the support shaft 31). The central axis C2 of the voice coil 34 is located at a position offset by ΔZ (in one example, ΔZ = 3 mm) relative to the upward side (cover 14 side) of the central axis C1 of the actuator assembly, i.e., the side of the thicker upper magnet M2.

[0083] Therefore, as Figure 10 As shown in (b), even when the VCM24 is asymmetrically configured, for example, when the thicknesses of the upper and lower magnets M1 and M2 are different, the generation of pitch torque acting on the actuator assembly can be suppressed. That is, according to this embodiment, a disc device capable of suppressing the generation of residual vibration caused by the voice coil motor and improving positioning accuracy can be provided.

[0084] Furthermore, the height offset ΔZ is not limited to 3 mm and can be various values ​​depending on the thickness of the magnet, the number of disks, etc. The height offset ΔZ is preferably adjusted within a range of 0.3 to 3 mm.

[0085] Furthermore, the configuration is not limited to canceling out pitch torques Ty1 and Ty2 to a 100% degree. For example, even with a cancellation rate of around 80%, pitch torque can be reduced, thereby improving HDD performance. For instance, the height offset ΔZ can be adjusted such that, when the read / write head 17 is moved to the innermost or outermost position of the disk 18, the absolute value of the difference between the absolute values ​​of pitch torque Ty1 and pitch torque Ty2 is less than or equal to 2% of the absolute value of pitch torque Ty1, i.e., (||Ty2|-|Ty1||) / |Ty1|≤0.2, and the direction of the torque is opposite.

[0086] Figure 11 This is a top view showing the actuator assembly 22 rotated to the inner circumference of the disk. Figure 12This is a top view showing the state in which the actuator assembly 22 is rotated to the outer periphery of the disk.

[0087] To counteract the pitch torque, in addition to the aforementioned height offset ΔZ, the magnitude of Fx is also one of the adjustment parameters. The resultant force Fx in the length direction X is mainly generated at the overlap between the outer arc portion 34a of the roughly fan-shaped voice coil 34 and the lower magnet M1 and upper magnet M2 in the height direction Z. Therefore, the value of Fx can be adjusted by adjusting the overlap width D between the magnet and the coil arc portion 34a.

[0088] like Figure 11 As shown, the resultant force Fx is represented by the sum of the forces fx generated in each part of the arc portion 34a of the voice coil 34 (Fx = Σfx). The magnetization directions of the magnetization regions M1a and M1b (M2a and M2b) of magnets M1 and M2 are opposite to each other. Therefore, the vector directions of the forces fx generated in each part of the arc portion 34a are opposite at the locations opposite to the magnetization regions M1a (M2a) and M1b (M2b).

[0089] Figure 13 It is a diagram schematically showing the relationship between the width (overlap width OD) of the portion of the outer arc portion 34a of the voice coil that overlaps with the magnets M1 and M2 and the magnitude of the force Fx generated in the voice coil 34.

[0090] like Figure 13 (a) to Figure 13 As shown in (d), it can be seen that when the overlap width OD is set to 0mm, 0.95mm, 2.15mm, and 3.5mm, the larger the overlap width OD, the larger the value of the resultant force Fx per unit current. Therefore, by adjusting the resultant force Fx to adjust the generated pitch torque Ty2 to a value that counteracts the pitch torque TY1, the same effect as the aforementioned implementation method can be obtained.

[0091] Furthermore, in the above embodiments, as an example of an asymmetrical VCM configuration, an example is shown where the thicknesses d and d2 of magnets M1 and M2 are different. However, this configuration is not limited to this example, and other configurations may also be used. As other examples of asymmetrical configurations, configurations in which the thicknesses of magnets M1 and M2 are the same (d1 = d2), and the thicknesses of the lower yoke 37a and the upper yoke 37b are different can be listed.

[0092] Next, other embodiments of the HDD will be described. In the other embodiments described below, the same reference numerals are used for the parts that are the same as those in the first embodiment described above, and their detailed descriptions are omitted or simplified. The focus is on the parts that are different from the first embodiment.

[0093] (Second Implementation)

[0094] Figure 14 This is a cross-sectional view of an HDD including the bearing portion of the actuator assembly of the HDD according to the second embodiment, the voice coil motor (VCM), and the spindle of the spindle motor.

[0095] In the HDD of the second embodiment, the size and arrangement of the printed circuit board 50, as well as the asymmetrical structure of the VCM, are different from those of the first embodiment.

[0096] like Figure 14 As shown, in the second embodiment, the printed circuit board 50 is formed to be approximately 2 / 3 the size of the area of ​​the bottom wall 12a. The printed circuit board 50 is disposed in a shallow recess formed in the bottom wall 12a. The region of the printed circuit board 50 in the bottom wall 12a opposite to the disk 18 is located at a position offset from the region opposite to the VCM 24. That is, the printed circuit board 50 does not overlap with the region opposite to the VCM 24.

[0097] With the printed circuit board 50's dimensions and configuration as described above, a spatial margin is created in the area below the VCM24. In the VCM24, the thickness d1 of the lower magnet M1 in the height direction Z differs from the thickness d2 of the upper magnet M2 in the height direction Z. That is, the VCM24 has an asymmetrical configuration. In this embodiment, the lower magnet M1 is thicker than the upper magnet M2, and d1 > d2.

[0098] The voice coil 34, supported by the actuator assembly 22, is located between the lower magnet M1 and the upper magnet M2, facing them. The voice coil 34 is configured such that its central axis C2 in the longitudinal direction is offset by ΔZ in the height direction Z relative to the central axis C1 of the actuator assembly 22, which passes through the center CZ between the two bearings 28a and 28b. In this embodiment, the voice coil 34 is located at a position offset by ΔZ relative to the central axis C1 towards the thicker side of the base wall, i.e., the lower magnet M1. Thus, the central axis C2 of the voice coil 34 is centered in the height direction Z of the gap between the lower magnet M1 and the upper magnet M2.

[0099] The height offset ΔZ is adjusted within the range of 0.3 to 3 mm, depending on factors such as the thickness of the magnet and the number of disks.

[0100] In the second embodiment, the other components of the HDD are common to the HDD in the first embodiment. In the second embodiment with the above-described configuration, the same effects as in the first embodiment can also be achieved. That is, according to the second embodiment, a disk device capable of suppressing the generation of residual vibrations caused by the voice coil motor and improving positioning accuracy can be provided.

[0101] (Third Implementation)

[0102] Figure 15 This is a cross-sectional view of an HDD including the bearing portion of the actuator assembly of the HDD according to the third embodiment, the voice coil motor (VCM), and the spindle of the spindle motor.

[0103] In the HDD of the third embodiment, the size and arrangement of the printed circuit board 50, as well as the asymmetrical structure of the VCM, are different from those of the first embodiment.

[0104] like Figure 15 As shown, in the third embodiment, the printed circuit board 50 is formed to have an area approximately equal to that of the bottom wall 12a. The printed circuit board 50 is disposed facing each other across approximately the entire surface of the bottom wall 12a. Furthermore, in the cover 14, a recess is provided in the region facing the VCM24, and a vibration damping plate 78 is disposed in this recess. The vibration damping plate 78 is attached to the cover 14 by an adhesive layer 76.

[0105] In the HDD configured as described above, the upper magnet M2 of VCM24 is thinner than the lower magnet M1. That is, the thickness d1 of the lower magnet M1 in the height direction Z is different from the thickness d2 of the upper magnet M2 in the height direction Z, and VCM24 has an asymmetrical configuration. As described above, in this embodiment, the lower magnet M1 is thicker than the upper magnet M2, and is set as d1 > d2.

[0106] The voice coil 34, supported by the actuator assembly 22, is located between the lower magnet M1 and the upper magnet M2, facing these magnets. The voice coil 34 is configured such that its central axis C2 in the longitudinal direction is offset by ΔZ in the height direction Z relative to the central axis C1 of the actuator assembly 22, which passes through the center CZ between the two bearings 28a and 28b. In this embodiment, the voice coil 34 is located at a position offset by ΔZ relative to the central axis C1 towards the lower magnet M1, which is the thicker side of the base wall. Thus, the central axis C2 of the voice coil 34 is centered in the height direction Z of the gap between the lower magnet M1 and the upper magnet M2.

[0107] The height offset ΔZ is adjusted within the range of 0.3 to 3 mm, depending on factors such as the thickness of the magnet and the number of disks.

[0108] In the third embodiment, the other components of the HDD are common to the HDD in the first embodiment. In the third embodiment with the above-described configuration, the same effects as those in the first embodiment can also be achieved. That is, according to the third embodiment, a disk device capable of suppressing the generation of residual vibrations caused by the voice coil motor and improving positioning accuracy can be provided.

[0109] This invention is not limited to the embodiments described above, and can be embodied by modifying the constituent elements during implementation without departing from its essence. Furthermore, various inventions can be formed through appropriate combinations of the multiple constituent elements disclosed in the above embodiments. For example, several constituent elements can be deleted from all the constituent elements shown in the embodiments. Moreover, constituent elements involved in different embodiments can be appropriately combined.

[0110] For example, in a disk drive, the number of disks and the number of read / write heads can be increased or decreased as needed, and the disk size can also be selected in various ways.

Claims

1. A disk device comprising: The housing includes a base having a bottom wall and a cover opposite to the bottom wall; A disc-shaped recording medium is rotatably disposed within the housing; The head processes information on the recording medium; An actuator assembly includes an actuator block, a suspension assembly, and a support frame. The actuator block is rotatably supported by a pair of bearings on a support shaft erected on the bottom wall and extending in a first direction. The suspension assembly extends from the actuator block in a direction intersecting the support shaft and mounts the head. The support frame extends from the actuator block. as well as A coil motor causes the actuator assembly to rotate. The coil motor includes: a lower magnetic yoke disposed on the bottom wall; A lower magnet is disposed on the lower yoke; an upper yoke is positioned opposite the lower yoke at a distance from it in the first direction. An upper magnet, disposed on the upper yoke and spaced apart from the lower magnet in the first direction; and a voice coil, fixed to the support frame of the actuator assembly and located between the lower and upper magnets, wherein the upper and lower magnets have different thicknesses in the first direction. The actuator assembly has a first central axis that passes through the center between the pair of bearings and is orthogonal to the support axis. The voice coil has a coil center axis that passes through the center in the first direction and extends parallel to the first central axis, and is positioned at a height that is offset relative to the first central axis in the first direction.

2. The disk device according to claim 1, The voice coil is positioned at a height offset toward the thicker side of the upper or lower magnet.

3. The disk device according to claim 2, The thickness of the upper magnet in the first direction is greater than the thickness of the lower magnet in the first direction. The voice coil is positioned at a height offset from the first central axis toward the upper magnet.

4. The disc device according to claim 2, The thickness of the lower magnet in the first direction is greater than the thickness of the upper magnet in the first direction. The voice coil is positioned at a height offset from the first central axis toward the lower magnet side.

5. The disk device according to claim 1, The offset of the height position is greater than 0.3mm and less than 3mm.

6. The disk device according to claim 3, The disk device also includes a printed circuit board disposed opposite to the outer surface of the bottom wall. The printed circuit board is offset from the region in the bottom wall opposite to the recording medium and is positioned opposite to the region opposite to the coil motor.

7. The disc device according to claim 4, The disk device also includes a printed circuit board disposed opposite to the outer surface of the bottom wall. The printed circuit board is offset from the region in the bottom wall opposite to the coil motor and is positioned opposite to the region opposite to the recording medium.

8. The disk device according to claim 1, When the head is at the innermost or outermost circumference position of the data recording area of ​​the recording medium, the difference between the absolute value of the pitch torque caused by the force Fz in the first direction generated by the voice coil and the pitch torque caused by the force Fx in the direction of the coil central axis generated by the voice coil is less than 2% relative to the pitch torque caused by the force Fz in the first direction, and the direction of the torque is opposite.

9. The disk device according to claim 1, The voice coil has an outer arc portion, at least a portion of which overlaps with the lower magnet and the upper magnet in the first direction.

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