Load beam with shape memory alloy wire and load beam

Abstract

To provide a load beam with a shape memory alloy wire capable of easily returning a suspension to an origin position, and a load beam.SOLUTION: The load beam 30 with shape-memory-alloy wire includes a load beam 20 and shape-memory-alloy wires 41A and 41B connecting two points on the load beam 20.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a load beam with a shape memory alloy wire and a load beam. [Background technology]

[0002] Generally, a hard disk drive (HDD) is equipped with a suspension on which a magnetic head is mounted, which writes and reads data to and from a magnetic disk on which the data is stored. The suspension is mainly composed of a flexure and a load beam, and the magnetic head is mounted at the tip of the flexure. The load beam functions as a thin flat spring. The load beam supports the flexure so that the magnetic head maintains a desired floating attitude relative to the magnetic disk.

[0003] Hard disk drives are sometimes used in data centers, for example. With the recent expansion of diverse data usage, the storage capacity of hard disks used in data centers is expected to continue to increase. This has led to a demand for further improvements in hard disk recording density.

[0004] As the recording density per magnetic disk increases, high positioning accuracy is also required for suspensions. To address this, a method is known in which a piezoelectric element is mounted on either or both of the wired suspension and the load beam, and the suspension itself is moved to improve positioning accuracy (see Patent Document 1). However, conventionally, the suspension cannot be returned to its original position by itself. Therefore, it is necessary to grasp the original position of the suspension via a magnetic head and move it the required amount. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2024-1942 Summary of the Invention [Problem to be solved by the invention]

[0006] The present disclosure provides a load beam with a shape memory alloy wire and a load beam that allows the suspension to easily return to its original position. [Means for solving the problem]

[0007] The embodiments of the present disclosure relate to the following [1] to

[10] .

[0008] [1] A load beam with a shape memory alloy wire, comprising a load beam and a shape memory alloy wire connecting two points on the load beam.

[0009] [2] The load beam with shape memory alloy wire according to [1], wherein two shape memory alloy wires are provided.

[0010] [3] A load beam with shape memory alloy wires according to [2], wherein the two shape memory alloy wires cross each other in a plan view.

[0011] [4] A load beam with shape memory alloy wires according to [2], wherein the two shape memory alloy wires are spaced apart from each other in a planar view.

[0012] [5] A load beam with shape memory alloy wire described in any one of [2] to [4], wherein the two shape memory alloy wires are arranged symmetrically with respect to the central axis of the load beam.

[0013] [6] A load beam with a shape memory alloy wire according to any one of [1] to [5], wherein the shape memory alloy wire overlaps with a region corresponding to the tip actuator element in a plan view.

[0014] [7] A load beam with a shape memory alloy wire according to any one of [1] to [6], wherein the length of the shape memory alloy wire is 50% or more and 80% or less of the longitudinal distance of the load beam.

[0015] [8] A load beam with a shape memory alloy wire according to any one of [1] to [6], wherein the length of the shape memory alloy wire is 30% or more and less than 50% of the longitudinal distance of the load beam.

[0016] [9] The load beam is a load beam with a shape memory alloy wire described in any one of [1] to [8], comprising: a beam flat portion; a base end mounting portion formed on the beam flat portion and connecting the base end of the shape memory alloy wire; and a tip end mounting portion formed on the beam flat portion and connecting the tip end of the shape memory alloy wire.

[0017]

[10] A load beam comprising: a beam flat portion; a base end attachment portion formed on the beam flat portion and connecting a base end of a shape memory alloy wire; and a tip end attachment portion formed on the beam flat portion and connecting a tip end of the shape memory alloy wire. [Effects of the Invention]

[0018] According to the present disclosure, the suspension can be easily returned to the original position. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a perspective view showing a hard disk drive equipped with a suspension according to one embodiment. [Figure 2] FIG. 2 is a plan view of the suspension shown in FIG. 1 with a load beam according to one embodiment. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III shown in FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV shown in FIG. [Figure 5]FIG. 5 is a cross-sectional view showing a load beam blank plate for fabricating a load beam according to one embodiment. [Figure 6] FIG. 6 is a plan view showing a suspension according to a first modified example. [Figure 7] FIG. 7 is a plan view showing a suspension according to a second modified example. [Figure 8] FIG. 8 is a plan view showing a suspension according to another example of the second modified example. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings attached to this specification, the scale and aspect ratios of the actual objects have been appropriately changed and exaggerated for the sake of convenience in illustration and understanding.

[0021] As used herein, geometric conditions, physical characteristics, terms specifying the degree of a geometric condition or physical characteristic, and numerical values ​​indicating a geometric condition or physical characteristic may be interpreted without being bound by strict meaning. These geometric conditions, physical characteristics, terms, and numerical values ​​may be interpreted to include a range within which similar functionality can be expected. Examples of terms specifying geometric conditions include "length," "angle," "shape," "parallel," "orthogonal," and "identical." Furthermore, to clarify the drawings, the shapes of multiple parts that can be expected to have similar functionality are depicted in a regular pattern. However, without being bound by strict meaning, the shapes of the parts may differ from each other as long as the functionality can be expected. In the drawings, for convenience, boundary lines indicating the joining surfaces of components are shown as simple straight lines. However, they are not required to be strictly straight lines, and the shape of the boundary line is arbitrary as long as the desired joining performance can be expected.

[0022] A suspension, a load beam with a shape memory alloy wire, and a load beam according to an embodiment of the present disclosure will be described with reference to Figures 1 to 4. First, a hard disk drive 1 using a suspension 5 equipped with a load beam 20 according to this embodiment will be described with reference to Figure 1.

[0023] As shown in FIG. 1, a hard disk drive 1 includes a case 2, a magnetic disk 3, a spindle motor 4, a suspension 5, a voice coil motor 6, and a ramp 7. The magnetic disk 3 is configured to store data. The magnetic disk 3 is rotatably attached to the case 2. The magnetic disk 3 is configured to rotate by the spindle motor 4. The suspension 5 includes a flexure 11 and a load beam 20 (see FIG. 2). A magnetic head 12 (see FIG. 2) is mounted on the tip of the flexure 11. The magnetic head 12 is configured to write and read data to and from the magnetic disk 3. The load beam 20 supports the magnetic head 12 and the flexure 11 so that the magnetic head 12 is at a desired flying height relative to the magnetic disk 3 when writing and reading data. The suspension 5 is rotated by the voice coil motor 6, allowing the magnetic head 12 to move to a desired position on the magnetic disk 3.

[0024] 1 includes a plurality of magnetic disks 3 and a plurality of suspensions 5 in order to improve recording density. A magnetic head 12 attached to the suspension 5 writes and reads data to and from the upper and lower surfaces of each magnetic disk 3.

[0025] The ramp 7 is located near the magnetic disk 3 inside the case 2. When the magnetic disk 3 stops rotating, the suspensions 5 move together and retreat from the magnetic disk 3. At the retreated position, a tab 22 (described later) located at the tip of the load beam 20 is accommodated in the ramp 7. The ramp 7 is configured to support the tab 22.

[0026] Next, the suspension 5 according to this embodiment will be described.

[0027] As shown in FIG. 2, the suspension 5 includes a flexure 11, a load beam 20, a first piezoelectric element PZ1, a second piezoelectric element PZ2, and shape memory alloy wires 41A and 41B.

[0028] The flexure 11 is a flexible wiring board. The flexure 11 is joined to and supported by the load beam 20. The flexure 11 includes a plurality of wires. A magnetic head 12 is mounted on the tip of the flexure 11. Some of the wires electrically connect the magnetic head 12 to terminals connected to an external connection board (not shown). Other wires electrically connect each piezoelectric element (described later) to terminals connected to the external connection board. The flexure 11 is also called a wired flexure or a suspension flexure.

[0029] The load beam 20 extends in a longitudinal direction D1 and tapers toward a tip 20p. As shown in Fig. 2, the load beam 20 includes a first surface 20a and a second surface 20b located on the opposite side to the first surface 20a. The first surface 20a corresponds to the upper surface in Fig. 1, and the second surface 20b corresponds to the lower surface in Fig. 1. The load beam 20 will be described later.

[0030] The first piezoelectric element PZ1 is an example of an actuator element. The first piezoelectric element PZ1 is located on the opposite side of a hinge portion 26 of the load beam 20, which will be described later, from the tip 20p of the load beam 20.

[0031] The first piezoelectric element PZ1 is bonded to the first surface 20a of the load beam 20. The first piezoelectric element PZ1 expands and contracts when a voltage is applied, and moves the magnetic head 12 via the load beam 20 and the flexure 11. The first piezoelectric element PZ1 is set so that the expansion and contraction force when a voltage is applied is greater than that of the second piezoelectric element PZ2.

[0032] Two first piezoelectric elements PZ1 are bonded to the load beam 20. The two first piezoelectric elements PZ1 function to move the tip of the suspension 5 in the short-side direction D2. The two first piezoelectric elements PZ1 may be positioned symmetrically with respect to a central axis line CL (described later) in a plan view. The polarities of the two first piezoelectric elements PZ1 are opposite to each other. Each first piezoelectric element PZ1 expands and contracts when a voltage is applied, thereby slightly moving the magnetic head 12. Each first piezoelectric element PZ1 has a pair of opposing electrodes and a piezoelectric material portion interposed between the pair of electrodes. The piezoelectric material portion of each first piezoelectric element PZ1 is made of piezoelectric ceramics such as PZT (lead zirconate titanate). The piezoelectric material portions of the pair of first piezoelectric elements PZ1 are formed so that their polarization directions are 180° apart from each other. When a predetermined voltage is applied to the pair of first piezoelectric elements PZ1, one of the first piezoelectric elements PZ1 contracts, while the other first piezoelectric element PZ1 expands.

[0033] The second piezoelectric element PZ2 is an example of a tip actuator element. The second piezoelectric element PZ2 may also be called a tip piezoelectric element. The second piezoelectric element PZ2 is located closer to the tip 20p of the load beam 20 than the first piezoelectric element PZ1. The second piezoelectric element PZ2 is located closer to the tip 20p of the load beam 20 than a jig hole 27 of the load beam 20, which will be described later.

[0034] The second piezoelectric element PZ2 is bonded to the flexure 11. In this case, the second piezoelectric element PZ2 faces the second surface 20b of the load beam 20. The second piezoelectric element PZ2 expands and contracts when a voltage is applied, and moves the magnetic head 12 via the flexure 11. The second piezoelectric element PZ2 is set so that the expansion and contraction force when a voltage is applied is smaller than that of the first piezoelectric element PZ1.

[0035] Two second piezoelectric elements PZ2 are bonded to the flexure 11. The two second piezoelectric elements PZ2 may be positioned symmetrically with respect to the central axis line CL in a plan view. The polarities of the two second piezoelectric elements PZ2 are different from each other.

[0036] Next, the load beam 20 according to this embodiment will be described.

[0037] As shown in FIG. 2, the load beam 20 is configured to support the flexure 11 described above. The load beam 20 has a longitudinal direction D1 and a lateral direction D2. The load beam 20 extends in the longitudinal direction D1 so as to taper toward the tip 20p. The longitudinal direction D1 may be referred to as a first direction. The lateral direction D2 is perpendicular to the longitudinal direction D1 in a plan view. The lateral direction D2 may be referred to as a second direction. The plan view means that the load beam 20 is viewed in the normal direction of the first surface 20a at the beam flat portion 24 described below.

[0038] 2, the load beam 20 has a central axis CL along a longitudinal direction D1. The load beam 20 includes a tab 22 located on the tip side of the load beam 20 and a first piezoelectric element opening 29.

[0039] As shown in FIG. 2, the load beam 20 includes a base portion 23, a beam flat portion 24, a pair of edge portions 25, and a hinge portion .

[0040] The base portion 23 is located at the base of the load beam 20. A base plate (not shown) is joined to a first surface 20a of the base portion 23. A first piezoelectric element opening 29 is formed in the base portion 23.

[0041] The beam flat portion 24 is located closer to the tip 20p of the load beam 20 than the base portion 23. The beam flat portion 24 extends in the longitudinal direction D1. The beam flat portion 24 extends in a generally tapered shape toward the tip 20p of the load beam 20. The beam flat portion 24 is formed in a flat shape.

[0042] A jig hole 27 is formed in the beam flat portion 24. The jig hole 27 is located closer to the tip 20p of the load beam 20 than a hinge portion 26, which will be described later. A laser diode element opening 28, which accommodates a laser diode element (not shown), is formed in the beam flat portion 24. The laser diode element opening 28 is located closer to the tip 20p of the load beam 20 than the jig hole 27. The laser diode element is attached to the magnetic head 12 and passes through the laser diode element opening 28.

[0043] 2, the edge portions 25 are located on both sides of the beam flat portion 24 in the short-side direction D2 in a plan view. The edge portions 25 are portions bent relative to the beam flat portion 24. The edge portions 25 have a bent shape with the first surface 20a facing inward.

[0044] As shown in FIG. 2 , the hinge portion 26 is located between the base portion 23 and the beam flat portion 24. The hinge portion 26 connects the base portion 23 and the beam flat portion 24. The hinge portion 26 is bent with the second surface 20b facing inward so that the magnetic head 12 approaches the magnetic disk 3. The hinge portion 26 is formed to have low bending rigidity. More specifically, the hinge portion 26 includes a pair of hinge beams 26a, and the base portion 23 and the beam flat portion 24 are connected by the pair of hinge beams 26a. The pair of hinge beams 26a are spaced apart from each other in the short-side direction D2, and an opening is formed between the pair of hinge beams 26a. As a result, when the beam flat portion 24 is affected by an airflow generated by the rotation of the magnetic disk 3, the hinge portion 26 elastically deforms, allowing the magnetic head to maintain a desired flying height relative to the magnetic disk 3. A folding line (not shown) of the hinge portion 26 is aligned with the short-side direction D2. The hinge portion 26 is formed flat along the short-side direction D2.

[0045] 2, the tab 22 extends in an elongated shape in the longitudinal direction D1 from the beam flat portion 24 to the tip 20p of the load beam 20. The tip of the tab 22 forms the tip 20p of the load beam 20. When the suspension 5 is retracted onto the ramp 7, the tab 22 is supported by the ramp 7. The tab 22 may have a curved shape with the first surface 20a facing inward in a cross section perpendicular to the longitudinal direction D1.

[0046] The first piezoelectric element opening 29 is an opening for the first piezoelectric element PZ1 to mount the first piezoelectric element PZ1 on the load beam 20. The first piezoelectric element opening 29 is formed in the base portion 23 and penetrates the base portion 23. The first piezoelectric element opening 29 is located on the opposite side of the hinge portion 26 from the tip 20p of the load beam 20. The first piezoelectric element opening 29 is formed in a rectangular shape along the longitudinal direction D1 and the lateral direction D2 in a plan view. The first piezoelectric element PZ1 is bonded to the first surface 20a of the load beam 20 so as to overlap the first piezoelectric element opening 29. The first piezoelectric element PZ1 and the wiring of the flexure 11 are electrically connected via a connection portion (not shown) located in the first piezoelectric element opening 29.

[0047] 2, two first piezoelectric element openings 29 are formed in the base portion 23. The two first piezoelectric element openings 29 may be positioned symmetrically with respect to the central axis line CL in a plan view.

[0048] As shown in FIG. 3 , the thickness t1 of the beam flat portion 24 may be, for example, 25.0 μm or more and 35.0 μm or less. Setting the thickness t1 to 25.0 μm or more ensures the mechanical strength of the load beam 20 and reduces the possibility of plastic deformation of the load beam 20. Setting the thickness t1 to 35.0 μm or less reduces the thickness of the load beam 20. This reduces the thickness of the suspension 5, contributing to a reduction in the thickness of the hard disk drive 1. For example, the thickness t1 may be 25.0 μm or more and 30.0 μm or less, 27.0 μm or more and 30.0 μm or less, or 29.0 μm or more and 30.0 μm or less. The thickness t1 is the dimension of the beam flat portion 24 in the thickness direction D3 of the first surface 20a, and is the distance between the first surface 20a and the second surface 20b of the beam flat portion 24.

[0049] The load beam 20 may be made of a metal material such as stainless steel. Stainless steel is, for example, a metal material primarily composed of iron, chromium, and nickel. Examples of stainless steel include austenitic stainless steel, ferritic stainless steel, and martensitic stainless steel. Examples of stainless steel materials used in this embodiment include SUS304, SUS301, SUS316, and SUS430.

[0050] As shown in Figure 3, shape memory alloy wires 41A and 41B are attached to the load beam 20. The shape memory alloy wires 41A and 41B each connect two points on the load beam 20. The shape memory alloy wires 41A and 41B enable the suspension 5 to return to its original position by itself when the suspension 5 is tilted or distorted due to an external disturbance such as wind disturbance. For this reason, the shape memory alloy wires 41A and 41B are pre-memorized so that the suspension 5 returns to its original position.

[0051] The load beam 20 and the shape memory alloy wires 41A and 41B constitute a load beam with shape memory alloy wire 30. In this embodiment, such a load beam with shape memory alloy wire 30 is also provided.

[0052] The shape memory alloy wires 41A and 41B are each arranged on the first surface 20a on the beam flat portion 24. In this embodiment, two shape memory alloy wires 41A and 41B are attached to the load beam 20, but it is sufficient that at least one shape memory alloy wire is attached.

[0053] The two shape memory alloy wires 41A, 41B are each arranged at an incline with respect to the central axis CL in a plan view. One of the shape memory alloy wires 41A is inclined toward the negative side of the short-side direction D2 as it approaches the tip 20p of the load beam 20. The other shape memory alloy wire 41B is inclined toward the positive side of the short-side direction D2 as it approaches the tip 20p of the load beam 20. The two shape memory alloy wires 41A, 41B are arranged so as to be line-symmetrical with respect to the central axis CL. By arranging the two shape memory alloy wires 41A, 41B line-symmetrically, force is distributed evenly. This prevents excessive stress from being applied to a specific part of the load beam 20, improving the strength of the load beam 20.

[0054] The two shape memory alloy wires 41A and 41B each linearly connect two points on the load beam 20. Specifically, the shape memory alloy wires 41A and 41B each connect a base end mounting portion 42 and a tip end mounting portion 43. The base end mounting portion 42 and the tip end mounting portion 43 are each formed on the beam flat portion 24.

[0055] The base end of each shape memory alloy wire 41A, 41B is connected to the base end mounting portion 42. The base end mounting portion 42 is formed on the first surface 20a of the load beam 20. The base end mounting portion 42 is located farther from the tip 20p of the load beam 20 than the tip end mounting portion 43. The base end mounting portions 42 are located between the hinge portion 26 and the second piezoelectric element PZ2, near the hinge beam 26a. In this specification, the term "base end" refers to the end located farther from the tip 20p of the load beam 20.

[0056] The tip end of each shape memory alloy wire 41A, 41B is connected to the tip end side mounting portion 43. The tip end side mounting portion 43 is formed on the first surface 20a of the load beam 20. The tip end side mounting portion 43 is formed at a position closer to the tip end 20p of the load beam 20 than the base end side mounting portion 42. The tip end side mounting portions 43 are located between the tip end 20p of the load beam 20 and the second piezoelectric element PZ2, near the boundary between the tab 22 and the beam flat portion 24. In this specification, the "tip end" refers to the end portion located closer to the tip end 20p of the load beam 20.

[0057] As shown in FIG. 3, between the base end side mounting portion 42 and the tip end side mounting portion 43, the shape memory alloy wires 41A and 41B are arranged spaced apart from the first surface 20a of the load beam 20.

[0058] As shown in FIG. 4 , the base-end attachment portion 42 and the tip-end attachment portion 43 each protrude from the beam flat portion 24 toward the first surface 20a. The base-end attachment portion 42 and the tip-end attachment portion 43 may each be formed by bending a portion of the beam flat portion 24. Specifically, the base-end attachment portion 42 and the tip-end attachment portion 43 may be bent into a V-shape while sandwiching the ends of the shape memory alloy wires 41A and 41B, thereby fixing the shape memory alloy wires 41A and 41B. The ends of the shape memory alloy wires 41A and 41B may be fixed to the base-end attachment portion 42 or the tip-end attachment portion 43 by crimping, crimping, or welding. In particular, it is preferable to fix the ends of the shape memory alloy wires 41A and 41B by crimping. This is because crimping is a mechanical connection that is resistant to vibrations and is less susceptible to wind disturbances. Note that some components, such as the flexure 11, are not shown in FIG. 4 .

[0059] As shown in FIG. 2, the two shape memory alloy wires 41A, 41B intersect with each other at an intersection Pw in a plan view. That is, in a plan view, one of the two shape memory alloy wires 41A, 41B overlaps the other. The intersection Pw is preferably located on the central axis CL. The intersection Pw is located closer to the tip than the longitudinal center of each shape memory alloy wire 41A, 41B. The intersection Pw is located closer to the tip 20p of the load beam 20 than the second piezoelectric element PZ2. It is preferable that the two shape memory alloy wires 41A, 41B are spaced apart from each other at the intersection Pw in the thickness direction D3 of the load beam 20. In other words, it is preferable that the two shape memory alloy wires 41A, 41B do not come into contact with each other.

[0060] It is preferable that each shape memory alloy wire 41A, 41B is provided so as to overlap with the second piezoelectric element PZ2 in a plan view, so that the suspension 5 can be returned to the origin position with higher accuracy after the suspension 5 is operated by the second piezoelectric element PZ2.

[0061] The shape memory alloy wires 41A, 41B are filaments made of a shape memory alloy. Examples of shape memory alloys include titanium-nickel alloys and iron-based shape memory alloys. The shape memory alloy wires 41A, 41B have the property that even if they are deformed below a certain temperature (transformation point), they will recover to their original shape when heated above that temperature. This temperature (transformation point) may be a temperature below room temperature. The shape memory alloy wires 41A, 41B may be superelastic wires.

[0062] In FIG. 2, the length L2 of the shape memory alloy wires 41A and 41B may be 50% or more and 80% or less of the longitudinal distance L1 of the load beam 20. By making the length L2 of the shape memory alloy wires 41A and 41B 50% or more of the longitudinal distance L1 of the load beam 20, the shape memory alloy wires 41A and 41B are made longer, which makes it easier to absorb large deformations. As a result, when the suspension 5 is deformed, the shape of the suspension 5 is easily restored by the restoring force of the shape memory alloy wires 41A and 41B. By making the length L2 of the shape memory alloy wires 41A and 41B 80% or less of the longitudinal distance L1 of the load beam 20, the shape memory alloy wires 41A and 41B can be reliably positioned within the plane of the load beam 20. The length L2 of the shape memory alloy wires 41A and 41B may be 3 mm or more and 10 mm or less.

[0063] The longitudinal distance L1 of the load beam 20 may be 7 mm or more and 14 mm or less. The longitudinal distance L1 of the load beam 20 refers to the maximum length of the load beam 20 measured parallel to the central axis CL.

[0064] Next, a load beam blank plate 60 for manufacturing the above-mentioned load beam 20 will be described with reference to FIG.

[0065] 5 is a cross-sectional view of a load beam blank plate 60 for manufacturing the load beam 20. The load beam blank plate 60 is in a state before the edge portion 25 is bent as described above, and is formed in an entirely flat shape.

[0066] In a plan view, the load beam blank plate 60 extends in the longitudinal direction D1 in a tapered manner toward the tip of the load beam blank plate 60. The tip of the load beam blank plate 60 corresponds to the tip 20p of the load beam 20. The load beam blank plate 60 is bent along a bending line (not shown) to separate the beam flat portion 24 from an edge portion 25. The load beam blank plate 60 has the jig hole 27, the laser diode element opening 28, and the first piezoelectric element opening 29 described above formed therein.

[0067] The load beam blank plate 60 may be supported by a frame (not shown) that surrounds the load beam blank plate 60. The load beam 20 according to this embodiment may be obtained by bending the load beam blank plate 60 while it is supported by the frame. In this case, the load beam 20 may be supported by the frame. A plurality of load beam blank plates 60 may be supported on the frame. In this case, a multi-sided load beam 20 can be produced. A multi-sided load beam 20 means a configuration in which a plurality of load beams 20 are supported by one frame.

[0068] As shown in FIG. 5, the first surface 20a and the second surface 20b of the load beam blank plate 60 are each formed flat. The first surface 20a and the second surface 20b may be parallel to each other. The hinge portion 26 described above is also in a state before bending, and is formed flat not only in the short-side direction D2 but also in the long-side direction D1. The base-end mounting portion 42 and the tip-end mounting portion 43 described above are formed by bending a portion of the load beam blank plate 60.

[0069] The thickness of the load beam blank plate 60 is equal to the thickness t1 of the beam flat portion 24.

[0070] (Load beam manufacturing method) Next, a method for manufacturing the load beam 20 according to this embodiment having the above-described configuration will be described.

[0071] First, a flat plate-like member is prepared. For example, the plate-like member may be a rolled material having the thickness t1 described above.

[0072] Next, a load beam blank plate 60 is formed by photolithography as shown in Fig. 5. More specifically, the outer shape of the load beam blank plate 60 is formed, and a jig hole 27, a laser diode element opening 28, and a first piezoelectric element opening 29 are also formed.

[0073] Next, the load beam blank plate 60 is bent. This forms the edge portion 25 shown in FIG. 2. The portion of the load beam blank plate 60 corresponding to the hinge portion 26 is bent to form the hinge portion 26. The tip of the load beam blank plate 60 is shaped to have a curved shape, forming the tab 22. Furthermore, by bending a portion of the beam flat portion 24, the base end side mounting portion 42 and the tip end side mounting portion 43 are formed.

[0074] In this manner, the load beam 20 according to this embodiment is obtained.

[0075] Next, the shape memory alloy wires 41A, 41B are attached to the load beam 20. Specifically, the base end of each shape memory alloy wire 41A, 41B is connected to the base end side mounting portion 42, and the tip end of each shape memory alloy wire 41A, 41B is connected to the tip end side mounting portion 43. At this time, the two shape memory alloy wires 41A, 41B cross each other in a plan view. In this way, the load beam 30 with shape memory alloy wire according to this embodiment is obtained.

[0076] Next, the flexure 11 (see FIG. 2) is bonded to the load beam 20 to fabricate the suspension 5. The second piezoelectric element PZ2 is previously bonded to the flexure 11. After the flexure 11 is bonded to the load beam 20, the first piezoelectric element PZ1 is placed over the first piezoelectric element opening 29 of the load beam 20, and the first piezoelectric element PZ1 is bonded to the first surface 20a of the load beam 20.

[0077] Thereafter, the magnetic head 12 is mounted on the tip of the flexure 11, and a laser diode element is attached to the magnetic head 12. When the suspension 5 is attached to the case 2 shown in FIG.

[0078] In the hard disk drive 1 thus fabricated, the magnetic disk 3 rotates at high speed. The positioning voice coil motor 6 also moves the suspension 5 in the radial direction DO (FIG. 1) of the magnetic disk 3. This moves the magnetic head 12 to a desired position on the magnetic disk 3.

[0079] Next, when a voltage is applied to the first piezoelectric element PZ1, the first piezoelectric element PZ1 expands and contracts, thereby enabling the magnetic head 12 located at the tip of the suspension 5 to be moved precisely and quickly in the short-side direction D2.

[0080] As described above, while the hard disk drive 1 is in use, the suspension 5 may tilt or distort due to external disturbances such as wind disturbances. In this embodiment, shape memory alloy wires 41A and 41B are provided to connect two points on the load beam 20. The shape memory alloy wires 41A and 41B memorize the origin position of the suspension 5 and have the property of restoring the suspension 5 to the shape of the origin position. This allows the suspension 5 to return to the origin by itself when the suspension 5 tilts or distorts due to external disturbances such as wind disturbances. This allows the suspension 5 to be positioned easily and with high accuracy. The transformation points of the shape memory alloy wires 41A and 41B may be set to a temperature below room temperature. In this case, the shape memory alloy wires 41A and 41B will recover to their original shape at room temperature without being heated.

[0081] In particular, in this embodiment, a first piezoelectric element PZ1 and a second piezoelectric element PZ2 are mounted on the suspension 5. In this case, after the suspension 5 is operated by the first piezoelectric element PZ1 and the second piezoelectric element PZ2, the suspension 5 can return to its original position by itself. Therefore, there is no need to know the original position of the suspension 5 through the magnetic head 12, and the suspension 5 can be controlled simply.

[0082] Furthermore, according to this embodiment, the suspension 5 mechanically returns to the origin, so even if the size of the first piezoelectric element PZ1 or the second piezoelectric element PZ2 is reduced, the function of the first piezoelectric element PZ1 or the second piezoelectric element PZ2 can be exhibited.

[0083] Furthermore, according to this embodiment, two shape memory alloy wires 41A and 41B are provided. The two shape memory alloy wires 41A and 41B cross each other at the intersection Pw in a plan view. This allows the load beam 20 to be moved in a balanced manner on both sides of the intersection Pw using the shape memory alloy wires 41A and 41B, thereby moving the suspension 5 to the origin position. By arranging the shape memory alloy wires 41A and 41B so that they cross each other, it becomes possible to evenly distribute the force applied by the airflow inside the hard disk drive 1. This reduces excessive stress on specific parts of the suspension 5, enabling stable magnetic recording. Furthermore, the stability of the suspension 5 is improved, making it possible to extend the product life.

[0084] Furthermore, according to this embodiment, the shape memory alloy wires 41A and 41B overlap with the region corresponding to the second piezoelectric element PZ2 in plan view, which allows the suspension 5 to be returned to the origin position with higher accuracy after the suspension 5 is operated by the second piezoelectric element PZ2.

[0085] (Variation) Next, modified examples of the load beam with shape memory alloy wire according to this embodiment will be described with reference to Figures 6 to 8. In Figures 6 to 8, the same parts as those in Figures 1 to 5 are designated by the same reference numerals, and detailed description thereof will be omitted.

[0086] (First Modification) In the above-described embodiment, an example has been described in which the two shape memory alloy wires 41A and 41B intersect with each other in a planar view. However, this is not limited to this. For example, as shown in FIG. 6, the two shape memory alloy wires 41A and 41B may be spaced apart from each other in a planar view. The two shape memory alloy wires 41A and 41B are each arranged at an angle with respect to the central axis CL in a planar view. The shape memory alloy wires 41A and 41B approach each other as they move toward the tip 20p of the load beam 20. The shape memory alloy wires 41A and 41B do not intersect with the central axis CL in a planar view. It is also preferable that the two shape memory alloy wires 41A and 41B are arranged so as to be symmetrical with respect to the central axis CL.

[0087] 6, the tip-side mounting portions 43 are located between the tip 20p of the load beam 20 and the second piezoelectric element PZ2, near the boundary between the tab 22 and the beam flat portion 24. The base-side mounting portions 42 are located between the hinge portion 26 and the second piezoelectric element PZ2, near the hinge beam 26a. It is preferable that each shape memory alloy wire 41A, 41B is provided so as to overlap the area where the second piezoelectric element PZ2 is arranged in a plan view.

[0088] According to this modification, the two shape memory alloy wires 41A, 41B are spaced apart from each other in a plan view, so there is no risk of the two shape memory alloy wires 41A, 41B coming into contact with each other when the suspension 5 is returned to its original position. Furthermore, the two shape memory alloy wires 41A, 41B are arranged so that they are inclined with respect to the central axis CL in a plan view and approach each other toward the tip 20p of the load beam 20. This allows the load beam 20 to more easily absorb deformation even when the load beam 20 undergoes a wide range of deformation. The two shape memory alloy wires 41A, 41B exert a stronger pulling force on each other, improving the ability to restore the original shape. This arrangement is particularly preferable when the load beam 20 itself is thin and prone to deformation, since the deformation will be widespread.

[0089] (Second Modification) In the above-described embodiment, an example has been described in which the length L2 of the shape memory alloy wires 41A, 41B is 50% or more and 80% or less of the longitudinal distance L1 of the load beam 20. However, this is not limited to this. For example, as shown in Figures 7 and 8, the length L2 of the shape memory alloy wires 41A, 41B may be 30% or more and less than 50% of the longitudinal distance L1 of the load beam 20.

[0090] 7 and 8, the tip-side mounting portion 43 is located between the tip 20p of the load beam 20 and the second piezoelectric element PZ2, near the boundary between the tab 22 and the beam flat portion 24. The base-side mounting portion 42 is located between the hinge portion 26 and the second piezoelectric element PZ2, near the jig hole 27. The two shape memory alloy wires 41A and 41B are preferably arranged so as to be symmetrical with respect to the central axis CL. Furthermore, each shape memory alloy wire 41A and 41B is preferably arranged so as to overlap the area where the second piezoelectric element PZ2 is arranged in a plan view.

[0091] As shown in Figure 7, the two shape memory alloy wires 41A, 41B may be arranged so as to cross each other in a plan view. In this case, by arranging the shape memory alloy wires 41A, 41B so as to cross each other, it becomes possible to evenly distribute the force applied by the airflow inside the hard disk drive 1. This reduces excessive stress on specific parts of the suspension 5, enabling stable magnetic recording. It also improves the stability of the suspension 5, making it possible to extend the product life.

[0092] Alternatively, as shown in FIG. 8, the two shape memory alloy wires 41A, 41B may be arranged spaced apart from each other in a plan view. The two shape memory alloy wires 41A, 41B are arranged so that they are inclined with respect to the central axis CL in a plan view and approach each other toward the tip 20p of the load beam 20. This makes it easier to absorb deformation even when the load beam 20 deforms over a wide range. The two shape memory alloy wires 41A, 41B exert a stronger pulling force on each other, improving the ability to restore to the original shape. This arrangement is preferable, especially when the load beam 20 itself is thin and easily deformed, because the deformation will be widespread.

[0093] According to this modification, the length L2 of the shape memory alloy wires 41A, 41B is 30% or more and less than 50% of the longitudinal distance L1 of the load beam 20. This makes it possible to operate the portion of the suspension 5, particularly the portion near the tip 20p of the load beam 20, with greater precision when returning the suspension 5 to the origin position.

[0094] It is also possible to combine the multiple components disclosed in the above embodiments and modifications as needed, or to delete some of the components disclosed in the above embodiments and modifications. [Explanation of symbols]

[0095] 1 hard disk drive 5. Suspension 11 Flexure 12 Magnetic head 20 Load beam 22 tabs 24 Beam flat section 26 Hinge part 30 Load beam with shape memory alloy wire 41A Shape Memory Alloy Wire 41B Shape Memory Alloy Wire 42 Base end mounting part 43 Tip side mounting part

Claims

1. A load beam with shape memory alloy wire, A load beam, and a shape memory alloy wire connecting two points on the load beam.

2. 2. The load beam with shape memory alloy wire according to claim 1, wherein two shape memory alloy wires are provided.

3. 3. The load beam with shape memory alloy wire according to claim 2, wherein the two shape memory alloy wires cross each other in a plan view.

4. 3. The load beam with shape memory alloy wire according to claim 2, wherein the two shape memory alloy wires are spaced apart from each other in a plan view.

5. 3. The load beam with shape memory alloy wire according to claim 2, wherein the two shape memory alloy wires are arranged symmetrically with respect to a central axis of the load beam.

6. 2. The load beam with shape memory alloy wire according to claim 1, wherein the shape memory alloy wire overlaps with a region corresponding to a tip actuator element in a plan view.

7. 2. The load beam with shape memory alloy wire according to claim 1, wherein the length of said shape memory alloy wire is 50% or more and 80% or less of the longitudinal distance of said load beam.

8. 2. The load beam with shape memory alloy wire according to claim 1, wherein the length of said shape memory alloy wire is 30% or more and less than 50% of the longitudinal length of said load beam.

9. 2. The load beam with shape memory alloy wire according to claim 1, wherein the load beam comprises: a beam flat portion; a base end attachment portion formed on the beam flat portion and connecting a base end of the shape memory alloy wire; and a tip end attachment portion formed on the beam flat portion and connecting a tip end of the shape memory alloy wire.

10. A load beam, a beam flat portion; a base end side attachment portion formed on the flat portion of the beam and connecting a base end portion of the shape memory alloy wire; a tip-side attachment portion formed on the beam flat portion and connecting the tip end of the shape memory alloy wire.

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