JP2006134563A - Micro-actuator, head gimbal assembly, and disk drive unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a micro-actuator and a HGA that finely adjust a head position and have excellent resonance characteristics. <P>SOLUTION: The HGA includes a slider 31, a micro-actuator 32 comprising a bottom plate 393, a moving plate 394, and two arm plates 391 and 392 symmetrically disposed with an axis of the bottom plate as symmetry axis to connect the moving plate 394 and the bottom plate 393; and at least one piezoelectric element 321 to be bonded to the arm plates; and a suspension 17 where the slider 31 and the micro-actuator 32 are to be mounted. The slider 31 is mounted on the moving plate 394 and rotated when at least one piezoelectric element 321 is excited. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a disk drive unit, and more particularly, to a microactuator and a head gimbal assembly using the microactuator.

  A disk drive is an information storage device that uses a magnetic medium to store data. Referring to FIG. 1, a typical disk drive in this technical field has a magnetic disk and a drive arm for moving a head gimbal assembly 277 (HGA) (HGA 277 is a suspension (not numbered) and And an attached slider 203). A disk is mounted on a spindle motor that rotates the disk, and a voice coil motor (VCM) is equipped to control the operation of the drive arm, thereby reading the data from the disk or writing data to the disk. Controls the movement of the slider 203 which moves from track to track across the track.

  However, due to the inherent tolerance associated with the movement of the slider 203 (away from the track) by the VCM, the slider 203 cannot be precisely aligned, which means that the slider 203 reads data from the magnetic disk and the magnetic disk. Adversely affects writing data to

  In order to solve the above problem, a piezoelectric (PZT) microactuator is currently used to correct the movement of the slider 203. That is, the PZT microactuator corrects the displacement of the slider 203 on a very small scale in order to compensate for the tolerance for resonance between the VCM and the suspension. This makes it possible to reduce the track width and increase the “tracks per inch” (TPI) of the disk drive unit by 50% (this is equivalent to increasing the surface storage density).

  Referring to FIG. 1b, a conventional PZT microactuator 205 includes a ceramic U-shaped frame 297 with a ceramic beam 207 having two PZT elements (not numbered) on either side thereof. Referring to FIGS. 1 a and 1 b, the PZT microactuator 205 is physically coupled to the suspension 213, 3 on one side of the ceramic beam 207 for coupling the microactuator 205 to the suspension print pattern 210. There are individual connection balls (gold ball bonding, or solder ball bonding, GBB or SBB). In addition, there are four metal balls 208 (GBB or SBB) to electrically couple the slider 203 with the suspension 213. FIG. 1 c shows the detailed process of inserting the slider 203 into the microactuator 205. The slider 203 is bonded to the two ceramic beams 207 at two points 206 by an epoxy piece 212 so that the movement of the slider 203 depends on the ceramic beam 207 of the microactuator 205.

  When power is supplied through the print pattern 210 of the suspension, the PZT element of the microactuator 205 expands or contracts, deforms the two ceramic beams 207 of the U-shaped frame 297, and moves the slider 203 on the disk track. Move to. In this way, fine course adjustment can be performed.

  However, since the PZT microactuator 205 and the slider 203 are on the suspension tongue (not numbered), when the PZT microactuator 205 is excited, the microactuator 205 is restricted by the U-shaped frame 297, A pure translational motion is performed by simply swinging the slider 203. This is a limitation on improving the servo bandwidth and HDD capacity. As shown in FIG. 2, numeral 201 indicates a resonance curve when the suspension base plate is shaken, and numeral 202 indicates a resonance curve when the microactuator 205 is excited. This figure clarifies the above problem.

  In addition, the microactuator 205 has additional mass that affects not only static performance but also dynamic performance such as resonance performance in order to reduce the resonance frequency and increase the gain of the suspension 213. I have it.

  As described above, the microactuator, HGA, and disk drive are desired to solve the above problems.

  The main feature of the present invention is to provide a microactuator and an HGA that can finely adjust the head position and can obtain good resonance characteristics when the microactuator is excited.

  Another feature of the present invention is to provide a disk drive unit having a large servo bandwidth and head position adjustment capability.

  In order to achieve the above characteristics, the HGA of the present invention is placed symmetrically with respect to the axis of the bottom plate as a symmetry axis for coupling the microactuator having the slider and the bottom plate, the moving plate, and the moving plate and the bottom plate. Two arm plates, at least one piezoelectric element bonded to the arm plate, and a suspension for attaching the slider and the microactuator. The slider is attached to the moving plate, and has at least one The piezoelectric element rotates when excited.

  In one embodiment, the moving plate includes a support portion that supports the slider and two coupling portions that are coupled to the support portion on a diagonal line. Each of the two coupling portions has a narrower width than the support portion. The slider is partially attached to a support portion of the support frame, and the centers of the slider and the support portion coincide with each other. In another embodiment, two coupling portions are coupled to the two arm plates that are placed symmetrically with respect to the center line of the support frame by two coupling points. The distance between the two arm plates is greater than the width of the slider so that two gaps are formed between them. In the present invention, the bottom plate is partially attached to the suspension, and a parallel gap is formed between the support frame and the suspension. The arm plate is formed on both sides of both the bottom plate and the moving plate, and at least a space exists between the arm plate and the bottom plate or between the arm plate and the moving plate. At least one PZT element is attached to one side or both sides of each arm plate. The material for adhering the slider to the support frame and the material for adhering the bottom plate of the support frame to the suspension are epoxy, adhesive, or ACF.

  The microactuator of the present invention includes a bottom plate, a moving plate to which a slider is attached and rotated, and two arm plates placed symmetrically with respect to the axis of the bottom plate as a symmetry axis for coupling the moving plate and the bottom plate. And at least one piezoelectric element bonded to the two arm plates. In one embodiment, the moving plate includes a support portion that supports the slider and two coupling portions that are coupled to the support portion on a diagonal line. Each of the two coupling parts has a narrower width than the support part. At least one of the piezoelectric elements is a thin film piezoelectric element or a ceramic piezoelectric element, and has a single layer structure or a multilayer structure having a substrate layer and a piezoelectric layer. The piezoelectric layer may be a single layer PZT structure or a multilayer PZT structure, and the substrate layer is made of metal or ceramic or polymer. In the present invention, the arm plate is formed on both sides of both the bottom plate and the moving plate, and at least a space exists between the arm plate and the bottom plate or between the arm plate and the moving plate. At least one PZT element is attached to one side or both sides of each arm plate. The material for bonding the slider to the support frame is epoxy, adhesive, or ACF.

  The disk drive unit of the present invention includes an HGA, a drive arm coupled to the HGA, a disk, and a spindle motor that rotates the disk. The HGA includes a slider and a microactuator including a bottom plate. A moving plate, two arm plates placed symmetrically with respect to an axis of the bottom plate as a symmetry axis for coupling the moving plate and the bottom plate, and at least one piezoelectric element bonded to the arm plate; The slider and a suspension for mounting the microactuator, wherein the slider is attached to the moving plate and rotated by the moving plate when at least one piezoelectric element is excited, and the bottom plate is Partially seated in its pension, characterized in that there are parallel gaps between the suspension and the support frame.

  Compared to the prior art, the microactuator uses a PZT element to deflect the arm plate, and the slider is partially attached to the moving plate so that the slider can be rotated to rotate the slider. The moving plate is rotated. When the slider rotates with the moving plate with a narrow width around its center, the two joints of the support frame prevent the slider from moving laterally. Since the center of the moving plate coincides with the center of the slider, the slider can be servo-controlled without exciting the HGA in the roll mode.

  In the present invention, both the back and front of the slider can be rotated in different directions so that the slider can be moved in a greater range. Since the slider rotates around its center, a wide head position adjustment capability and a wide servo control bandwidth can be achieved. In general, a microactuator that adjusts a slider by rotation can achieve three times the efficiency compared to a microactuator that adjusts a slider by parallel movement (for example, the prior art). Since the microactuator of the present invention adjusts the slider by a rotational motion that does not perform a parallel motion, the efficiency is three times that of the prior art. In addition, since the slider is narrower than the distance between the two arm plates that form two parallel gaps between them, the slider can be rotated more freely over a large range when the microactuator is excited. . Further, the resonance of the suspension does not occur at a low frequency, and only the resonance of a pure microactuator occurs at a high frequency, which can widen the servo bandwidth and improve the HDD capacity. Finally, the configuration of the microactuator exhibits better performance against shock than the U-shaped ceramic frame.

  In order to facilitate understanding of the present invention, some embodiments will be described in detail with reference to the accompanying drawings.

  Referring to FIG. 3, a head gimbal assembly (HGA) 3 according to the present invention includes a slider 31, a microactuator 32, and a suspension 8 to which the slider 31 is attached.

  3 to 5, the suspension 8 includes a load beam 17, a flexure 13, a hinge 15, and a base plate 11. The load beam 17 has a dimple 329 (see FIG. 6) formed thereon. On the flexure 13, a plurality of coupling pads 308 are provided at one end for coupling to a control system (not shown), and a plurality of electrical multi-print patterns 309 and 311 are provided at the other end. The flexure 13 also includes a suspension tongue 328 that supports the microactuator 32 and the slider 31 and is used to constantly apply a load to the center of the slider 31 through the dimples 329 of the load beam 17. The suspension tongue 328 has a plurality of electrical bond pads 113 and 310 thereon. The slider 31 has a plurality of electrical adhesive pads 204 corresponding to the adhesive pads 113 of the suspension tongue 328 at the end thereof.

  4 and 5, according to the embodiment of the present invention, the microactuator 32 includes a support frame 320 and two PZT elements 321. Each of the PZT elements 321 has a plurality of electrical adhesive pads 333 corresponding to the adhesive pads 310 of the suspension tongue 328 thereon. The support frame 320 can be made of metal (ie, stainless steel) or ceramic or polymer, and consists of a bottom plate 393, a moving plate 394, and two side plates 391, 392. The side plates 391 and 392 are placed symmetrically with the axis of the bottom plate 393 as the axis of symmetry, and each is coupled to the bottom plate 393 and the moving plate 394. In this embodiment, the distance between the side plates 391 and 392 is larger than the width of the slider 31, and when the slider 31 is attached to the support frame 320, the two gaps 315 are between the support frame 320 and the slider 31. It is formed. In addition, the moving plate 394 includes a support portion 10 that supports the slider 31 and two coupling portions 11 and 12 that are coupled to the support portion 10 by two portions at both ends of a diagonal line of the support portion 10. Each of the coupling portions 11 and 12 is narrower than the support portion 10, and therefore, the notch 14 is formed between the side plate 391 and the support portion 10, and the cut portion (not numbered) is the side plate 392. It is formed between the support part 10. In order to increase the elasticity of the support frame 320, two notches 16 can be formed between the bottom plate 393 and the side plates 391, 392. In the present embodiment, the support portion 10 has a cubic shape and is vertically coupled to the coupling portions 11 and 12.

  Referring to FIGS. 4 and 5, the limiter 207 penetrates the suspension tongue 328 onto the load beam 17 so that the suspension tongue 328 does not bend excessively during normal operation of the disk drive and does not give shock or vibration to the disk drive. Is provided. In the present invention, the PZT element 321 can be bonded to the support frame 320 by a conventional bonding method such as epoxy bonding or anisotropic conductive film (ACF) bonding. The two PZT elements 321 are preferably made of thin film PZT elements that can be single layer PZT elements or multilayer PZT elements. As one embodiment, each PZT element 321 has a multilayer structure having an inner substrate layer and an outer PZT layer. The substrate layer can be made of ceramic or polymer or metal. The outer PZT layer can be a single layer PZT element or a multilayer PZT element.

  3 to 8, the PZT element 321 is bonded to the support frame 320 to form the microactuator 32, and then the slider 31 is coupled to the support portion 10 of the microactuator 32. The actuator 32 is attached to the suspension 8 to form the HGA 3 as follows. That is, first, the support frame 320 of the flexure 13 is partially coupled to the suspension tongue 328 by ACF, adhesive, or epoxy, and a parallel gap is maintained between the support frame 320 and the suspension tongue 328. Then, the electrical adhesive pads 333 of the two PZT elements 321 are electrically bonded to the electrical adhesive pads 310 of the suspension tongue 328 for the purpose of electrically coupling the microactuator 32 to the two printed patterns 311 of the suspension. For this purpose, a plurality of metal balls 332 (GBB or SBB) are used. At the same time, in order to electrically couple the slider 31 and the multi-print pattern 309, a plurality of metal balls 405 are used to electrically couple the electric adhesive pad 204 and the electric adhesive pad 113 of the slider 31. Through the multi-print patterns 309 and 311, the coupling pad 308 electrically couples the slider 31 and the microactuator 32 with a control system (not shown). Obviously, the HGA 3 can also be formed as follows. That is, first, the microactuator 32 is coupled to the suspension 8, and the slider is attached to the microactuator 32.

  5 and 7, the slider 31 is coupled to the support portion 10 by the epoxy band 18, and the centers of the slider 31 and the support portion 10 are well aligned. In one embodiment, epoxy bands 18 are symmetrically arranged at both ends of the support portion 10 with the center as a symmetry point.

  8, 9a, 9d and 10 show a first method of manipulating the microactuator 32 to perform the position adjustment function. In the present embodiment, the two PZT elements 321 have the same polarization direction, and are grounded in common at one end 404 as shown in FIG. 9A, and the same sine wave waveform 407 (see FIG. 9) at the other ends 401a and 401b. 9d) are applied. FIG. 8 shows an initial state of the microactuator 32 when no voltage is applied. When a sinusoidal voltage is applied to the two PZT elements 321, both PZT elements 321 gradually contract in the first half cycle as the voltage increases, and become a short position (corresponding to the maximum displacement position), and As the voltage decreases, it gradually returns to its original position.

  Referring to FIGS. 10 and 7, when the two PZT elements 321 are both contracted, the two side plates 391 and 392 are bent to move the movable portions 394 of the two coupling portions 11 and 12 in the opposite directions. The two coupling parts 11 and 12 are coupled with the support part 10 along the diagonal line, and each of the coupling parts 11 and 12 is narrower than the support part 10, so that the support part 10 is displaced from the original position 501 to the maximum around its center. It rotates to the position 502 and returns to the original position 501 by the action of the rotational torque generated from the two coupling portions 11 and 12. Therefore, the slider 31 is partially coupled to the support portion 10 by the epoxy band 18 and the center of the slider 31 and the center of the support portion 10 are in good agreement. Rotate around the center from the original position 501 to the maximum displacement position 502 and return to the original position 501. In addition, two gaps are formed between the slider 31 and the support frame 320 in order to ensure free rotation of the slider 31.

  Referring to FIGS. 8, 9a, 9d and 11, when the driving voltage 407 enters the second half cycle (becomes the opposite phase of the first half cycle), the negative voltages of the two PZT elements 321 increase. Both gradually expand to the maximum displacement position and return to the original position as the negative voltage decreases. Therefore, the slider 31 rotates from the original position 501 to the maximum displacement position 503 and returns to the original position. Thereby, since the slider 31 rotates around its center, fine adjustment of the head position is achieved.

  8, 9a, 9c and 10, 11 show another way of manipulating two PZT elements 321 to perform the position adjustment function. In this embodiment, the two PZT elements 321 have two different polarization directions, and are grounded in common at one end 404 and waveforms 406, 406 having different phases from the other ends 401a and 401b, as shown in FIG. 9b. Two voltages with 408 (see FIG. 9c) are applied. Driven by the voltage, both PZT elements 321 gradually shrink to the shortest position in the same half cycle and return to their original position, and when the voltage enters the next half cycle, both PZT elements 321 , Extend to the longest position and return to the original position. Similarly, the slider 31 rotates around its center to achieve fine adjustment of the head position.

  In the present invention, the width of each coupling portion 11, 12 being narrower than the width of the support portion 10 of the support frame 32 helps the rotation of the support portion 10 and the slider 31. That is, since the width is narrow, the coupling portions 11 and 12 can be bent easily in order to rotate the support portion 10 and the slider 31. Further, referring to FIG. 6, the parallel gap formed between the moving plate 394 and the suspension tongue 328 allows the support 10 and the slider 31 to rotate more freely when driven by the PZT element 321. Become.

  Compared with the prior art, the slider 31 is rotated around its center using two PZT elements 321 for rotating the moving plate so that both the rear surface and the front surface of the slider 31 can be moved in different directions. Prior art microactuators can only be moved to swing the back surface of the slider (since the front surface is fixed). As described above, according to the present invention, the fine position adjustment of the slider can be performed more efficiently than the prior art. Therefore, a large head position adjustment capability can be obtained.

  FIG. 12 shows the test results of the resonance performance of the HGA of the present invention, where 701 shows a base plate excitation resonance curve and 702 shows a microactuator excitation resonance curve. From this, it can be seen that the resonance of the suspension does not occur at a low frequency, and that when the microactuator 32 is excited, only the resonance of the pure microactuator occurs at a high frequency, thereby increasing the servo bandwidth and improving the HDD capacity. Thus, the seek time and correction time of the slider can be reduced.

  Referring to FIGS. 13 to 15, in the present invention, the support frame 32 may have other configurations, for example, other shapes (such as rhombuses) where the support portion 10 is not cubic. Alternatively, the coupling portions 11 and 12 may be coupled to the support portion 10 at a predetermined coupling angle (not 90 degrees). A cutout 15 may be provided between the coupling portion 11 (12) and the support portion 10 so that the coupling portions 11 and 12 can be easily bent.

  According to these three embodiments of the present invention, referring to FIGS. 16 to 18, the support portion 10 may have an outer shape constituted by a gentle arc. In addition, the coupling portions 11 and 12 may have a curved shape. Further, in order to balance the force acting on the support part 10, the connection parts 11 and 12 are connected to the side plates 391 and 392 at a connection point 500 that is symmetrically arranged with the meridian axis of the support frame as a symmetry axis. In the present invention, the PZT element can be installed on one side or both sides of each side plate 391,392.

  In the present invention, referring to FIG. 19, the disk drive unit of the present invention can be made by assembling the housing 108, the disk 101, the spindle motor 102, and the VCM 107 having the HGA 3 of the present invention. Since the configuration of the disk drive unit and / or the manufacturing process are well known to those skilled in the art, such configuration and assembly parts are omitted here.

It is a perspective view of HGA in a prior art. It is the elements on larger scale of FIG. Fig. 2 shows a detailed process of inserting the slider of Fig. Ia into an HGA microactuator. Fig. 2 shows a resonance curve of the HGA of Fig. La. 1 is a perspective view of an HGA according to a first embodiment of the present invention. It is the elements on larger scale of HGA of FIG. FIG. 5 is an exploded view of FIG. 4. FIG. 4 is a partial side view of the HGA of FIG. 3. It is a perspective view of the microactuator which attached the slider by FIG. The initial state when the voltage of the micro actuator which attached the slider of FIG. 7 is not applied is shown. FIG. 9 shows the electrical coupling relationship of two PZT elements of the microactuator of FIG. 8, wherein the PZT elements are polarized in the same direction according to one embodiment of the present invention. FIG. 9 shows the electrical coupling relationship of two PZT elements of the microactuator of FIG. 8, wherein the PZT elements are polarized in opposite directions according to another embodiment of the present invention. Fig. 9b shows waveforms of two voltages applied to each of the two PZT elements of Fig. 9b. FIG. 9b shows the waveform of one voltage applied to each of the two PZT elements of FIG. 9b. FIG. 9 shows two different ways of operating the microactuator with the slider of FIG. 8 when energized. FIG. 9 shows two different ways of operating the microactuator with the slider of FIG. 8 when energized. Fig. 4 shows a resonance curve of the HGA in Fig. 3. FIG. 6 is a perspective view of one of the different support frames of a microactuator according to three embodiments of the present invention. FIG. 6 is a perspective view of one of the different support frames of a microactuator according to three embodiments of the present invention. FIG. 6 is a perspective view of one of the different support frames of a microactuator according to three embodiments of the present invention. FIG. 6 is a schematic diagram of one of the different microactuators according to three embodiments of the present invention. FIG. 6 is a schematic diagram of one of the different microactuators according to three embodiments of the present invention. FIG. 6 is a schematic diagram of one of the different microactuators according to three embodiments of the present invention. 1 is a perspective view of a disk drive unit according to an embodiment of the present invention.

Explanation of symbols

3 Head gimbal assembly 8 Suspension 11, 12 Coupling parts 14, 16 Notch 31 Slider 32 Microactuator 101 Disk 102 Spindle motor 107 VCM
108 Housing 320 Support frame 321 PZT elements 391, 392 Side plate 393 Bottom plate 394 Moving plate

Claims (20)

A slider,
A bottom plate, a moving plate, two arm plates placed symmetrically with respect to the axis of the bottom plate as a symmetry axis for coupling the moving plate and the bottom plate, and at least one piezoelectric element bonded to the arm plate; A microactuator comprising:
A suspension for attaching the slider and the microactuator;
A head gimbal assembly comprising:
The head gimbal assembly, wherein the slider is attached to the moving plate and rotates when at least one of the piezoelectric elements is excited.   2. The head gimbal assembly according to claim 1, wherein the moving plate includes a support portion that supports the slider and two coupling portions that are diagonally coupled to the support portion. 3.   The head gimbal assembly according to claim 2, wherein each of the two coupling parts has a narrower width than the support part.   3. The head gimbal assembly according to claim 2, wherein the slider is partially attached to a support portion of the support frame, and the center of the slider and the support portion coincides.   3. The head gimbal assembly according to claim 2, wherein two coupling portions are coupled to the two arm plates that are placed symmetrically with respect to a center line of the support frame by two coupling points. 4. .   The head gimbal assembly according to claim 1, wherein a distance between the two arm plates is larger than a width of the slider.   The head gimbal assembly according to claim 1, wherein the bottom plate is partially attached to the suspension, and there is a parallel gap between the support frame and the suspension.   The arm plate is formed on both sides of both the bottom plate and the moving plate, and there is at least a space between the arm plate and the bottom plate or between the arm plate and the moving plate. The head gimbal assembly according to claim 1.   The head gimbal assembly according to claim 1, wherein the at least one PZT element is attached to one side or both sides of each arm plate.   The head gimbal assembly according to claim 1, wherein the material for bonding the slider to the support frame and the material for bonding the bottom plate of the support frame to the suspension are epoxy, adhesive, or ACF. . A bottom plate,
A moving plate that attaches and rotates a slider;
Two arm plates placed symmetrically about the axis of the bottom plate as a symmetry axis for coupling the moving plate and the bottom plate;
At least one piezoelectric element bonded to the two arm plates;
A microactuator comprising:   The microactuator according to claim 11, wherein the moving plate includes a support portion that supports the slider and two coupling portions that are coupled to the support portion on a diagonal line.   13. The microactuator according to claim 12, wherein each of the two coupling parts has a narrower width than the support part.   The microactuator according to claim 11, wherein at least one of the piezoelectric elements is a thin film piezoelectric element or a ceramic piezoelectric element.   The microactuator according to claim 11, wherein at least one of the piezoelectric elements has a single layer structure or a multilayer structure including a substrate layer and a piezoelectric layer.   The microactuator according to claim 15, wherein the piezoelectric layer has a single-layer PZT structure or a multilayer PZT structure, and the substrate layer is made of metal, ceramic, or polymer.   The arm plate is formed on both sides of both the bottom plate and the moving plate, and there is at least a space between the arm plate and the bottom plate or between the arm plate and the moving plate. The microactuator according to claim 11.   The microactuator according to claim 11, wherein the at least one PZT element is attached to one side or both sides of each arm plate.   The microactuator according to claim 11, wherein a material for bonding the slider to the support frame is epoxy, an adhesive, or ACF. A head gimbal assembly;
A drive arm coupled to the head gimbal assembly;
A disc,
A disk drive unit comprising a spindle motor for rotating the disk,
The head gimbal assembly is
A slider,
A bottom plate, a moving plate, two arm plates placed symmetrically with respect to the axis of the bottom plate as a symmetry axis for coupling the bottom plate, and at least one piezoelectric element bonded to the arm plate; A microactuator comprising the slider and a suspension for mounting the microactuator;
It is characterized by comprising,
The slider is attached to the moving plate and rotated by the moving plate when energizing at least one piezoelectric element, and the bottom plate is partially attached to the suspension, and is interposed between the support frame and the suspension. Characterized by the presence of parallel gaps,
Disk drive unit

Images