JP4382051B2 - Magnetic head assembly, magnetic disk drive, and magnetic head assembly driving method - Google Patents

Description

The present invention relates to a magnetic head assembly, a magnetic disk device, and to a method of driving a magnetic head assembly, particularly high magnetic head assembly of positioning accuracy, a magnetic disk device, and a method of driving a magnetic head assembly.

  In recent years, miniaturization and precision of information equipment have progressed, and the demand for actuators that can control minute movements has increased. For example, focus correction and tilt angle control of an optical system, an ink jet printer, a head actuator of a magnetic disk device, and the like require a microactuator that can move and position a minute distance with high accuracy.

  For magnetic disk devices, it has become increasingly important to increase the recording capacity without increasing the dimensions. In general, increasing the capacity of a magnetic disk device is achieved by increasing the storage capacity per disk. In order to achieve a high recording density without changing the size of the disk, that is, the diameter, the number of tracks (TPI) per unit length (1 inch) in the radial direction is increased, that is, the width of the track is reduced. It is essential to do. For this reason, it is necessary to increase the positioning accuracy of the magnetic head in the track width direction, and there is a demand for the development of a microactuator for a magnetic head capable of high positioning accuracy.

  Conventional positioning of the magnetic head has been performed by rotationally driving a carriage arm, to which a suspension for holding the magnetic head (slider) is connected, around a rotation axis by a coarse actuator (voice coil motor). Even in this method, the recording density of the conventional medium is in a range that can be sufficiently covered. However, due to the increase in recording density accompanying the recent increase in capacity of recording apparatuses, the conventional method has insufficient positioning accuracy of the magnetic head, which may cause reading and writing defects of the magnetic head.

Japanese Patent No. 3041052 proposes that the carriage arm is rotationally driven by a voice coil motor, and the microactuator is disposed between the magnetic head slider and the suspension to improve the positioning accuracy of the magnetic head. The microactuator has a displacement generating part using a piezoelectric / electrostrictive material, and an applied voltage of 3 to 50 V, an in-plane moving distance of about 0.01 to 5 μm, and a rotation angle of about 0.05 to 2 degrees are exemplified. . Examples of the piezoelectric material include PZT [Pb (Zr, Ti) O ₃ ], PT [PbTiO ₃ ], PLZT [(Pb, La) (Zr, Ti) O ₃ ], barium titanate [BaTiO ₃ ], and the like. Yes.

  In Japanese Patent Laid-Open No. 2004-199823, a magnetic head slider is coupled to a suspension by a connecting member at a position passing through the center of gravity of the magnetic head slider, and a pair of piezoelectric elements are arranged in parallel on both sides of the center of gravity of the magnetic head slider. It is proposed to apply a rotational driving force to the magnetic head slider by bonding one end of the piezoelectric element to the magnetic head slider and bonding the other end to the suspension and contracting the piezoelectric element at a rotationally symmetric position. He teaches that the magnetic head slider can be driven at high speed because the rotational drive is performed with the center of gravity as the center of rotation.

  Japanese Patent Application Laid-Open No. 2006-14557 proposes to provide a step in at least one of the adhesion portion of the piezoelectric element and the adhesion portion of the opposing slider or suspension to restrict the distribution of the adhesive to make the adhesion area constant. . A configuration is also disclosed in which the coupling between the magnetic head slider and the suspension at the center of gravity of the magnetic head slider is omitted from the configuration proposed in Japanese Patent Laid-Open No. 2004-199823.

Japanese Patent No. 3041052 (International Publication WO98 / 19304) JP 2004-199823 A JP 2006-14557 A

An object of the present invention is to provide a magnetic head assembly, a magnetic disk device, and a magnetic head assembly driving method that can be driven at high speed and have high positioning accuracy.

Another object of the present invention is to provide a magnetic head assembly having high mechanical strength , a magnetic disk device, and a method for driving the magnetic head assembly .

Still another object of the present invention is to provide a magnetic head assembly, a magnetic disk apparatus, and a magnetic head assembly driving method that are easy to manufacture and have a small number of components.

According to one aspect of the present invention,
In a state in which a virtual plane assumed to be orthogonal to the virtual axis said virtual axis, at equal distances from the imaginary axis across the imaginary axis on the imaginary plane, in parallel with aligning the position of the longitudinal (1 /) of the first extension part and the second extension part that are rotationally symmetric with respect to the virtual axis, and the first extension part and the second extension part (1 / 2) A ceramic body including a connecting portion that connects each one end portion in the rotationally symmetric length direction on the virtual plane;
In (1/2) rotational symmetrical positions with respect to the imaginary axis, and a first piezoelectric element and the second piezoelectric element coupled to the side surface of said first extending portion and the second extending portion A piezoelectric actuator having
A suspension coupled to the connecting portion;
A magnetic head slider coupled to each of the other ends in the length direction of the first extension part and the second extension part at two (1/2) rotationally symmetric positions;
A magnetic head assembly is provided.

According to another aspect of the invention,
A magnetic disk having a disk surface;
A carriage arm having a suspension disposed above the magnetic disk and capable of being driven to rotate around a rotation axis;
A magnetic head assembly provided at a tip of the carriage arm;
The magnetic head assembly comprises:
In a state where a virtual axis and a virtual plane orthogonal to the virtual axis are assumed, the position in the length direction is aligned in parallel at a position equidistant from the virtual axis across the virtual axis on the virtual plane. (1 /) of the first extension part and the second extension part that are rotationally symmetric with respect to the virtual axis, and the first extension part and the second extension part (1 / 2) A ceramic body including a connecting portion that connects each one end portion in the rotationally symmetric length direction on the virtual plane;
A first piezoelectric element and a second piezoelectric element coupled to the side surfaces of the first extension part and the second extension part at (1/2) rotationally symmetric positions with respect to the virtual axis. A piezoelectric actuator having
A magnetic head slider coupled to each of the other ends in the length direction of the first extension part and the second extension part at two (1/2) rotationally symmetric positions;
A magnetic disk device is provided.

According to yet another aspect of the invention,
In a state where a virtual axis and a virtual plane orthogonal to the virtual axis are assumed, the position in the length direction is aligned in parallel at a position equidistant from the virtual axis across the virtual axis on the virtual plane. (1 /) of the first extension part and the second extension part that are rotationally symmetric with respect to the virtual axis, and the first extension part and the second extension part (1 / 2) A ceramic body including a connecting portion that connects each one end portion in the rotationally symmetric length direction on the virtual plane;
A first piezoelectric element and a second piezoelectric element coupled to the side surfaces of the first extension part and the second extension part at (1/2) rotationally symmetric positions with respect to the virtual axis. A piezoelectric actuator having
A suspension coupled to the connecting portion;
A magnetic head slider coupled to each of the other ends in the length direction of the first extension part and the second extension part at two (1/2) rotationally symmetric positions;
A method of driving a magnetic head assembly comprising:
A voltage is applied to the first piezoelectric element and the second piezoelectric element so that the first extending portion and the second extending portion are respectively connected to the first piezoelectric element side and the second piezoelectric element. A driving method of a magnetic head assembly is provided, wherein the magnetic head slider is bent in an arc shape on the piezoelectric element side, and the magnetic head slider is rotated by the bending .

  The ceramic body provides the mechanical strength of the piezoelectric actuator. When the piezoelectric element coupled to the ceramic body contracts, for example, the ceramic body is bent toward the piezoelectric element side, causing an arcuate displacement.

  By using an integral ceramic body, the number of parts is limited.

  The rotating object is driven to rotate by connecting the ceramic body to the support part at the connecting part and connecting the ceramic body to the rotating object at the (1/2) rotationally symmetric position of the extending part.

  When the magnetic head slider is coupled to the piezoelectric actuator at a (1/2) rotationally symmetric position with respect to the center of gravity of the magnetic head slider, the magnetic head slider is driven to rotate about the center of gravity as a rotation axis.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic plan view showing the configuration of a magnetic disk device. The figure shows the internal structure with the disk enclosure cover removed. A disk 32 that is driven to rotate by a spindle motor is disposed at the center of the enclosure 31 that seals the inside of the apparatus. A carriage arm 33 is provided in the vicinity of the outer periphery of the disk 32 so as to be rotatable about a rotation shaft 34. The carriage arm 33 extends on the disk 32, and a magnetic head assembly 35 is attached to the tip.

  A main actuator (voice coil motor) 36 that rotationally drives the carriage arm 33 is provided on the base end side of the carriage arm 33. A magnetic circuit having a magnetic gap is fixed on the enclosure 31 side, and a voice coil (moving coil) is fixed to the carriage arm 33. When a drive current is passed through the voice coil in the main actuator 36, thrust is generated in the voice coil portion in the magnetic gap, the carriage arm 33 rotates, and the magnetic head in the magnetic head assembly 35 moves in the track width direction of the disk 32. Move to T.

  FIG. 2A is an exploded perspective view showing the configuration of the magnetic head assembly 35. The magnetic head 11 shown at the bottom is for reading / writing data on the magnetic disk, and is mounted on the slider 12. The surface of the slider 12 facing the disk is a sliding surface parallel to the disk surface. When the disk rotates, the sliding surface floats from the disk surface.

  A substantially U-shaped punching hole 10 is formed at the tip of the leaf spring suspension 15 shown in the upper side in the drawing, and a slider holding portion 15a is defined at the center. The slider 12 is supported by the slider holding portion 15 a via the piezoelectric actuator 16.

  FIG. 2B is a plan view showing the configuration of the piezoelectric actuator 16. The piezoelectric actuator 16 includes a plate-shaped ceramic body 4 having a substantially rectangular overall shape, and a pair of piezoelectric elements 3a and 3b coupled to opposing side surfaces along the long sides 6a and 6b. The piezoelectric actuator has dimensions of, for example, a thickness of 0.1 mm, a short side width W = 0.313 mm, and a long side length L = 1.25 mm. The length L is basically matched to the size of the slider. In-plane gravity center position of the ceramic body 4 is indicated by G.

  Slits S1 and S2 are formed in the ceramic body 4 along the long sides 6a and 6b from the (1/2) rotationally symmetric position with respect to the center of gravity G of the opposing short sides 5a and 5b. The cantilever structures 4a and 4c are formed that are (1/2) rotationally symmetric with respect to G. The connecting portion or the central portion 4b supports the cantilever structures 4a and 4c at diagonal positions. The overall shape can be said to be N-shaped (or N mirror symmetric). The piezoelectric elements 3a and 3c are bonded to the outer surfaces of the cantilever portions 4a and 4c in a (1/2) rotational symmetry with respect to the center of gravity G.

  When a voltage is applied to contract the length of the piezoelectric elements 3a and 3b, the cantilever portions 4a and 4c are subjected to compressive stress on the outer surface, and are bent concavely toward the piezoelectric element side. Since one end of the cantilever beams 4a and 4c is coupled to the connecting portion 4b, the end portion away from the connecting portion moves outward.

  Returning to FIG. 2A, at two positions (1/2) rotationally symmetric with respect to the center of gravity of the slider 12, the adhesive layers 13 a and 13 b end the slider 12 away from the connecting portion of the cantilever 4 a and 4 c of the piezoelectric actuator 16. To join. The center of gravity position of the slider and the center of gravity of the ceramic body coincide in the plane. The adhesive layer 7 on the connecting portion 4 b of the piezoelectric actuator 16 adheres the piezoelectric actuator 16 to the slider holding portion 15 a of the suspension 15. Since the ceramic body 4 is fixed to the suspension 15, the center of gravity G is significant as a (1/2) rotationally symmetric axis of symmetry, and is not significant as a center of gravity.

  Since the slider is coupled to the suspension by one piezoelectric actuator formed integrally, alignment errors can be suppressed as compared with the case where a plurality of members are used. The slider is supported with its center of gravity aligned with the (1/2) rotationally symmetric axis of symmetry of the piezoelectric actuator.

  FIG. 3A is a plan view showing a state in which the slider 12 is bonded to the piezoelectric actuator 16. It is assumed that the slider 12 is arranged on a virtual plane indicated by a paper surface and the center of gravity is at the position G. A virtual axis passing through the center of gravity G and perpendicular to the virtual plane is assumed. The cantilevers 4a and 4c are arranged in parallel at a position equidistant from the virtual axis and in the length direction with the virtual axis in between. The cantilevers 4a and 4c are supported by diagonal portions of the connecting portion 4b that are (1/2) rotationally symmetric with respect to the center of gravity G. The piezoelectric elements 3a and 3b are bonded on the outer side surfaces of the cantilevers 4a and 4c at a position (1/2) rotationally symmetric with respect to the center of gravity G. When the ceramic body 4 is formed from a rectangular ceramic plate member, the center of gravity of the ceramic body is also aligned with the center of gravity of the slider in the plane. The adhesive layer 13 between the free ends of the cantilevers 4a and 4c and the slider 12 is in a position that is (1/2) rotationally symmetric with respect to the center of gravity G.

  When a voltage is applied to the piezoelectric elements 3a and 3b to cause the piezoelectric elements to contract in the length direction, the free ends of the cantilevers 4a and 4c move outward and rotate the slider 12 in the clockwise direction in the figure. . Since the slider 12 rotates about the center of gravity, the inertia is small and the resonance frequency is high. The slider can be driven at high speed.

A configuration example of the piezoelectric actuator will be described. The ceramic body 4 is made of zirconia having high rigidity. Use the _{PNN-PT-PZ [Pb (} NiNb) O 3 -PbTiO 3 -PbZrO 3] ceramic as the piezoelectric material of the piezoelectric element 3, as the electrode material to use Pt. A Pt electrode is printed on a PNN-PT-PZ green sheet, and a desired number of layers are stacked. Bake at 1050 ° C. in air. Then, it cuts with element width. The obtained piezoelectric element is bonded to the ceramic body. As the adhesive, a UV curable adhesive, a thermosetting adhesive, or the like can be used. Zirconia ceramics have high mechanical strength. PNN-PT-PZ has a large piezoelectric effect. By combining both, a piezoelectric actuator having high mechanical strength and sufficient displacement due to the piezoelectric effect can be created.

  FIG. 3B is a schematic diagram illustrating a calculation result. It was calculated that a displacement of 615 nm was obtained when a driving voltage of 45 V was applied to the piezoelectric element.

  FIG. 4 is a plan view showing a modification. The ceramic body 4 is the same as FIG. 2B in that the cantilever structures 4a and 4c are supported at diagonal positions of the connecting portion or the central portion 4b. The distance between the cantilevers 4a and 4c and the connecting portion 4b, that is, the width of the slits S1 and S2 is increased. The piezoelectric elements 3a and 3b are bonded to the outer surfaces of the cantilevers 4a and 4c, and the piezoelectric elements 3c and 3d are bonded to the inner surfaces. If a voltage is applied to the piezoelectric elements 3a and 3b, the cantilevers 4a and 4c are warped outward, and if a voltage is applied to the piezoelectric elements 3c and 3d, the cantilevers 4a and 4c are warped inward.

  In addition, when providing a space | interval between a pair of cantilever part and a connection part, the center of the free end of a pair of cantilever may not be the position of a gravity center. If the pair of cantilevers are antiparallel and aligned in the length direction and have a (1/2) rotationally symmetric shape, the center of gravity may be offset from the (1/2) rotationally symmetric axis. This is because the connecting portion is fixed to the support portion, and therefore the position of the center of gravity has no particular meaning.

  As mentioned above, although this invention was demonstrated along the Example, this invention is not restrict | limited to these. For example, instead of bonding a separately produced piezoelectric element to a ceramic body, a piezoelectric ceramic paste and an electrode paste can be formed on the ceramic body by a printing method. The ceramic body may be made of alumina, zirconia-alumina, or the like other than zirconia. As a piezoelectric material of the piezoelectric element, other than PNN-PT-PZ, for example, PZT, PLZT, or the like may be used. The piezoelectric material may be baked other than in the air, for example, in a vacuum. The electrode of the piezoelectric element may be made of, for example, silver (Ag) -palladium (Pd) other than Pt. It will be apparent to those skilled in the art that other various modifications, improvements, and combinations can be made.

  The features of the present invention will be described below.

(Appendix 1)
In a state where a virtual axis and a virtual plane orthogonal to the virtual axis are assumed, the positions in the length direction are aligned in antiparallel with the virtual axis on the virtual plane at a position equidistant from the virtual axis. First and second extending portions that are arranged (1/2) rotationally symmetric with respect to the virtual axis, and (1/2) rotationally symmetric between the first extending portion and the second extending portion. A ceramic body including an end portion connected on the virtual plane;
First and second piezoelectric elements coupled to side surfaces of the first and second extensions at a position that is (1/2) rotationally symmetric with respect to the virtual axis;
A piezoelectric actuator.

(Appendix 2)
The ceramic body has a plate shape, the first and second extending portions have a cantilever shape, and the first and second piezoelectric elements are bonded to at least one of both side surfaces of the cantilever beam. 2. The piezoelectric actuator according to appendix 1.

(Appendix 3)
The ceramic body has a rectangular outer shape defined by a pair of short sides and a pair of long sides as a whole on the virtual plane, and is rotated (1/2) with respect to the virtual axis of the pair of short sides. The piezoelectric actuator according to appendix 1 or 2, further comprising slits formed in parallel along the long side from a symmetrical position.

(Appendix 4)
4. The piezoelectric actuator according to claim 1, wherein an in-plane position of a center of gravity of the ceramic body coincides with a position of the virtual axis.

(Appendix 5)
The piezoelectric actuator according to any one of supplementary notes 1 to 4, wherein the ceramic body is formed of a ceramic containing zirconia, and the piezoelectric element includes PNN-PT-PZ as a piezoelectric material.

(Appendix 6)
The piezoelectric actuator according to any one of appendices 1 to 5,
A support portion coupled to the connecting portion of the ceramic body;
A rotating object coupled to an end of the ceramic body that is away from the connecting portion of the first extending portion and the second extending portion;
A micro-movement mechanism.

(Appendix 7)
A magnetic disk having a disk surface arranged parallel to the virtual surface;
A carriage arm having a suspension disposed above the magnetic disk and capable of being driven to rotate around a rotation axis;
The piezoelectric actuator according to any one of appendices 1 to 5, wherein a piezoelectric actuator in which a connecting portion of the ceramic body is coupled to the suspension;
A magnetic head slider coupled to ends of the first and second extending portions of the ceramic body away from the connecting portion;
A magnetic disk drive having

(Appendix 8)
The magnetic disk drive according to appendix 7, wherein a coupling surface for coupling the ceramic body and the magnetic head slider is located at a position (1/2) rotationally symmetric with respect to the center of gravity of the slider.

1 is a plan view showing a configuration of a magnetic disk device. 2A and 2B are an exploded perspective view of the magnetic head assembly and a plan view of the piezoelectric actuator. 3A and 3B are a plan view showing a state in which the piezoelectric actuator and the slider are coupled, and a plan view showing a calculation result of the operation of the piezoelectric actuator. It is a top view which shows a modification.

Explanation of symbols

3 Piezoelectric elements
4 Ceramic body 4a, 4c Cantilever part
7 Adhesive layer 11 Magnetic head 12 Slider 13a, 13b Adhesive layer
G Center of gravity S1, S2 Slit 15 Suspension 16 Piezoelectric actuator 31 Enclosure 32 Disk 33 Carriage arm 35 Magnetic head assembly 36 Main actuator

Claims (5)

In a state in which a virtual plane assumed to be orthogonal to the virtual axis said virtual axis, at equal distances from the imaginary axis across the imaginary axis on the imaginary plane, in parallel with aligning the position of the longitudinal (1 /) of the first extension part and the second extension part that are rotationally symmetric with respect to the virtual axis, and the first extension part and the second extension part (1 / 2) A ceramic body including a connecting portion that connects each one end portion in the rotationally symmetric length direction on the virtual plane;
In (1/2) rotational symmetrical positions with respect to the imaginary axis, and a first piezoelectric element and the second piezoelectric element coupled to the side surface of said first extending portion and the second extending portion A piezoelectric actuator having
A suspension coupled to the connecting portion;
A magnetic head slider coupled to each of the other ends in the length direction of the first extension part and the second extension part at two (1/2) rotationally symmetric positions;
A magnetic head assembly comprising: The ceramic body has a rectangular outer shape defined by a pair of short sides and a pair of long sides as a whole on the virtual plane, and is rotated (1/2) with respect to the virtual axis of the pair of short sides. 2. The magnetic head assembly according to claim 1, further comprising a slit formed in parallel along the long side from a symmetrical position. The magnetic head assembly according to claim 1, wherein the first extending portion, the second extending portion, and the connecting portion are integrally formed. A magnetic disk having a disk plane,
A carriage arm having a suspension disposed above the magnetic disk and capable of being driven to rotate around a rotation axis;
A magnetic head assembly provided at a tip of the carriage arm;
The magnetic head assembly comprises:
In a state where a virtual axis and a virtual plane orthogonal to the virtual axis are assumed, the position in the length direction is aligned in parallel at a position equidistant from the virtual axis across the virtual axis on the virtual plane. (1 /) of the first extension part and the second extension part that are rotationally symmetric with respect to the virtual axis, and the first extension part and the second extension part (1 / 2) A ceramic body including a connecting portion that connects each one end portion in the rotationally symmetric length direction on the virtual plane;
A first piezoelectric element and a second piezoelectric element coupled to the side surfaces of the first extension part and the second extension part at (1/2) rotationally symmetric positions with respect to the virtual axis. A piezoelectric actuator having
A magnetic head slider coupled to each of the other ends in the length direction of the first extension part and the second extension part at two (1/2) rotationally symmetric positions;
A magnetic disk drive comprising: In a state where a virtual axis and a virtual plane orthogonal to the virtual axis are assumed, the position in the length direction is aligned in parallel at a position equidistant from the virtual axis across the virtual axis on the virtual plane. (1 /) of the first extension part and the second extension part that are rotationally symmetric with respect to the virtual axis, and the first extension part and the second extension part (1 / 2) A ceramic body including a connecting portion that connects each one end portion in the rotationally symmetric length direction on the virtual plane;
  A first piezoelectric element and a second piezoelectric element coupled to the side surfaces of the first extension part and the second extension part at (1/2) rotationally symmetric positions with respect to the virtual axis. A piezoelectric actuator having
  A suspension coupled to the connecting portion;
A magnetic head slider coupled to each of the other ends in the length direction of the first extension part and the second extension part at two (1/2) rotationally symmetric positions;
A method of driving a magnetic head assembly comprising:
A voltage is applied to the first piezoelectric element and the second piezoelectric element so that the first extending portion and the second extending portion are respectively connected to the first piezoelectric element side and the second piezoelectric element. A method of driving a magnetic head assembly, wherein the magnetic head slider is bent in an arc shape on the piezoelectric element side, and the magnetic head slider is rotated by the bending.

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