JP3947488B2 - Actuator and slider unit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is an actuator for driving the magnetic head slider attached to the slider holder, and relates to a slider unit.
[0002]
[Prior art]
Conventionally, a piezoelectric device used for driving a magnetic head is known from Patent Document 1 and the like. The piezoelectric device described in Patent Document 1 connects a movable portion at a base that includes a pair of left and right movable portions and a fixed portion that fixes them at one end, and an end opposite to the end having the fixed portion. An attachment portion and a piezoelectric element disposed on a side surface of the movable portion are provided. Then, the magnetic head is attached to the attachment portion and the piezoelectric element is operated to move the movable portion to drive the magnetic head. According to the invention described in Document 1, a piezoelectric device can be configured with a small number of parts.
[0003]
[Patent Document 1]
JP 2002-289936 A [0004]
[Problems to be solved by the invention]
However, the invention described in the above document has the following problems in terms of product reliability. The piezoelectric element is usually attached with an adhesive, but the piezoelectric element is pressed against the movable part during the attachment for the purpose of making the adhesive uniform or the like. In the invention described in the above document, since the movable part is in a cantilever state where one end is fixed by the fixed part, bending stress is generated in the movable part due to the pressing force of the piezoelectric element at the time of attachment, and the movable part is distorted. In the worst case, the movable part may be broken. If the movable part is distorted, the accuracy of the drive displacement of the slider mounting part arranged in the movable part cannot be guaranteed.
[0005]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide an actuator and a slider unit that maintain the accuracy of displacement when the head slider is driven and have improved reliability.
[0006]
[Means for Solving the Problems]
The actuator according to the present invention includes a slider holding base that extends in one direction and has a slider mounting portion that is attached to a head slider having a thin film magnetic head at one end, and both sides of the slider holding base. And two piezoelectric elements that can be expanded and contracted in the extending direction of the slider holding table, and the slider holding table has a step on the recording medium facing surface facing the recording medium to be recorded / reproduced by the head slider. The side formed and lowered by this step constitutes a slider attachment portion, and the side raised by this step constitutes a piezoelectric element attachment portion for attaching a piezoelectric element .
[0007]
As described above, the piezoelectric element is attached to both sides of one slider holding base so that even if the piezoelectric element is pressed, no bending stress is generated in the slider holding base, so that the slider holding base is not distorted. Thereby, the accuracy of the displacement when the head slider is driven can be maintained, and the reliability of the actuator can be improved.
[0009]
In order to reduce the size of the apparatus, it is necessary to make the thickness of the slider unit completed by attaching the head slider to the actuator as thin as possible. For this reason, the slider attachment part which attaches a head slider is made low by the level | step difference .
[0010]
The actuator is further characterized in that a part of the surface opposite to the recording medium facing surface of the slider holding base is raised.
[0011]
In order to drive the head slider attached to the slider attachment portion, the slider holding base needs to bend according to the expansion and contraction of the piezoelectric element. According to the present invention, the configuration in which a part of the surface opposite to the recording medium facing surface is raised makes it easy to attach in a posture that does not contact the surface to which the actuator is attached except for the raised part. Thereby, it can bend smoothly except the raised part of a slide holding stand. In order to increase the displacement of the slider mounting portion when the slider holding base is bent by the action of the piezoelectric element, the raised fixing portion is preferably formed at the opposite end farthest from the slider mounting portion.
[0012]
A slider unit according to the present invention includes an actuator for attaching a head slider having a thin film magnetic head, and a head slider attached to a slider attachment portion of the actuator. The actuator extends in one direction, and the head slider is attached to the slider. One slider holding base having a slider mounting portion to be formed at one end, and two piezoelectric elements attached to both sides of the slider holding base and extendable in the extending direction of the slider holding base, Yes, and the slider holder is a step is formed on the recording medium facing surface facing the recording medium to be recorded and reproduced by the head slider, side is lowered by the step constitutes the slider attachment portion, it is higher by the step The other side constitutes a piezoelectric element mounting portion for mounting the piezoelectric element .
[0013]
As described above, the piezoelectric element is attached to both sides of one slider holding base so that even if the piezoelectric element is pressed, no bending stress is generated in the slider holding base, so that the slider holding base is not distorted. Thereby, the accuracy of the displacement when the head slider is driven can be maintained, and the reliability of the slider head can be improved. In order to reduce the size of the apparatus, it is necessary to make the thickness of the slider unit completed by attaching the head slider to the actuator as thin as possible. For this reason, the slider attachment part which attaches a head slider is made low by the level | step difference.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of a slider unit and an actuator according to the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.
[0017]
First, before describing the slider unit and the actuator according to the embodiment, a hard disk device to which these are applied will be described. FIG. 1 is a diagram showing a hard disk device provided with a head slider according to the present embodiment, and FIG. 2 is a head gimbal equipped with the slider unit 20 provided with the hard disk device shown in FIG. It is an expansion perspective view of an assembly. The hard disk device 1 operates a head gimbal assembly (HGA) 10 to record and reproduce magnetic information by a thin film magnetic head 11 on a recording surface (upper surface in FIG. 1) of a hard disk 2 that rotates at high speed. It is.
[0018]
As shown in FIG. 2, the head gimbal assembly 10 includes a metal suspension arm 12. The suspension arm 12 includes a gimbal 12a and a load beam 12b. A tongue portion 14 surrounded by a cut is formed on the tip end side of the suspension arm 12, and a slider unit 20 having a head slider 21 on which the thin film magnetic head 11 is formed is mounted on the tongue portion 14. . In FIG. 2, various wirings connected to the head slider 21 are omitted.
[0019]
As shown in FIG. 1, the head gimbal assembly 10 is rotatable around the support shaft 3 by, for example, a voice coil motor. When the head gimbal assembly 10 is rotated, the slider unit 20 moves in the radial direction of the hard disk 2, that is, in the direction crossing the track line.
[0020]
3 is a perspective view showing the slider unit 20 according to the first embodiment of the present invention, and FIG. 4 is an exploded perspective view of the slider unit 20 shown in FIG. The slider unit 20 is configured by attaching a head slider 21 to an actuator 23.
[0021]
First, the head slider 21 attached to the actuator 23 will be described. The head slider 21 has a substantially rectangular parallelepiped shape, and the thin film magnetic head 11 is formed on a base made of AlTiC (Al ₂ O ₃ · TiC). The upper surface in FIG. 3 is a recording medium facing surface that faces the recording surface of the hard disk 2 and is called an air bearing surface (ABS). When the hard disk 2 rotates, the head slider 21 is lifted by the air flow accompanying this rotation, and the air bearing surface S is separated from the recording surface of the hard disk 2. The air bearing surface S may be coated with DLC (Diamond Like Carbon) or the like.
[0022]
The actuator 23 according to the first embodiment includes a slider holding base 24 to which the head slider 21 is attached and two piezoelectric elements 25 attached to the slider holding base 24. The slider holding base 24 is an elongated member extending in one direction and is made of silicon. The material of the slider holding base 24 is not limited to silicon as long as it has strength and can be finely processed. For example, a metal such as SUS, a liquid crystal polymer, a resin such as polybutylene terephthalate (PBT) containing glass frit, or a ceramic such as alumina or zirconia can be used. The slider holding base 24 has a step 24c on a recording medium facing surface 24d facing the recording medium. The height of the recording medium facing surface 24d before and after the step 24c is changed, and the side lowered by the step 24c constitutes a slider mounting portion 24a for attaching the head slider 21, and the side raised by the step 24c is the piezoelectric element. A piezoelectric element mounting portion 24b to which 25 is mounted is configured. The step 24c formed on the recording medium facing surface 24d is preferably designed to be substantially the same as the height hs of the head slider 21 to be attached. Thereby, when the head slider 21 is attached to the slider attaching portion 24a, the height level of the ABS 24 of the attached head slider 21 and the recording medium facing surface 24d of the slider holding base 24 in the piezoelectric element attaching portion 24b is approximately the same. Therefore, the slider unit 20 can be prevented from being enlarged by suppressing the height of the slider unit 20. In order to increase the recording / reproduction efficiency of the head slider 21, it is preferable that the head slider 21 to be attached is designed to be slightly closer to the recording medium (several μm) than the slider holding base 24.
[0023]
The piezoelectric elements 25 are attached to both sides in the extending direction of the slider holding base 24. That is, on the piezoelectric element mounting portion side of the slider holding base 24, one is attached to each of the two surfaces 24b sandwiching the recording medium facing surface 24d by an adhesive such as epoxy, silicone, or acrylic. In the present embodiment, an electrode arrangement when the piezoelectric element 25 has a single plate structure is shown as an example. The piezoelectric element 25 has electrodes 25a and 25b on the front and back surfaces of a piezoelectric ceramic body such as PZT.
[0024]
The head slider 21 is attached to the slider attachment portion 24a of the actuator 23, and the slider unit 20 according to the embodiment is configured. The head slider 21 is attached to the actuator 23 so that the ABS faces the recording medium.
[0025]
The slider unit 20 is fixed to the tongue 14 of the gimbal 12a so that the side having the mounting surface 24a (see FIG. 4) of the head slider 21 faces the hard disk 2 as a recording medium. That is, the surface opposite to the recording medium facing surface 24d of the slide holding base 24 (hereinafter referred to as “gimbal fixing surface”) is fixed by being adhered to the tongue 14 of the gimbal 12a. At this time, a part of the gimbal fixing surface is fixed to the tongue part 14 and the parts other than the fixing part can be displaced by being separated from the tongue part 14, whereby the slider holding base 24 can be bent smoothly.
[0026]
Next, the manufacturing method of the actuator which concerns on embodiment of this invention is demonstrated. FIG. 5 is a diagram for explaining a manufacturing process of the actuator 23.
[0027]
First, a flat plate 30 made of silicon is prepared, and the flat plate 30 is etched using a mask not shown. In this etching step, a shape having a planar region 31 having a predetermined width w2 and a plurality of extending portions 32 extending perpendicularly from one side of the planar region 31 is formed. The planar region 31 is a portion that is cut in a later process to become the piezoelectric element mounting portion 24b. Accordingly, the etching is performed so that the width w2 of the planar region 31 is equal to the length l2 (see FIG. 4) of the piezoelectric element mounting portion 24b. In addition, the plurality of extending portions 32 are portions that are cut in a later step to become the slider mounting portion 24a. Accordingly, the width w1 of the extending portion 32 in the extending direction is equal to the thickness t1 (see FIG. 4) of the slider mounting portion 24a, and the extending length l3 is equal to the length l1 of the slider mounting portion 24a (see FIG. 4). Etched to be equal. Further, in a later step, the flat plate 30 is cut between the respective extension portions 32, and a connection portion between the extension portion 32 and the planar region 31 forms a step 24 c of the actuator 23. Therefore, the distance between the extending portions 32 is etched so as to be equal to or higher than the height of the piezoelectric element attaching portion 24b, the slider attaching portion 24a, and the step 24c. At the stage where this etching process is completed, as shown in FIG. 5A, a plurality of slider holding bases are still connected. FIG. 5A shows a shape in which two combinations of the planar region 31 and the extending portion 32 described above are arranged. In this way, it is possible to align an arbitrary number of shapes obtained by combining the planar region 31 and the extending portion 32. The flat plate 30 may be etched by either wet etching or dry etching.
[0028]
Next, the piezoelectric element 25 is attached to the flat plate 30 etched in the etching process. Electrodes 25a and 25b are already attached to the piezoelectric element 25 attached here. The piezoelectric element 25 has a rectangular parallelepiped shape extending in the direction in which the extending portions 32 are arranged. Although the back surface is not visible in FIG. 5B, the piezoelectric elements 25 are attached to both surfaces of the planar region 31. The piezoelectric element 25 is attached to the flat plate 30 by an adhesive such as epoxy, silicone, or acrylic.
[0029]
Subsequently, the flat plate 30 to which the piezoelectric element 25 is attached is cut in a cutting process, and the individual actuators 23 are cut out. As shown by a thick line in FIG. 5C, by cutting the flat plate 30 between one extending portion 32 and the adjacent extending portion 32 in parallel with the extending direction of the extending portion 32. Then, the piezoelectric element mounting portions 24b of the respective slider holding bases 24 are cut off, and the individual actuators 23 are cut out. Through the above steps, the actuator 23 according to the embodiment is completed.
[0030]
Next, the operation of the slider unit 20 according to this embodiment will be described. In the slider unit 20 according to this embodiment, piezoelectric elements 25 are attached to both sides of a slider holding base 24 to which the head slider 21 is attached. A voltage is applied between the electrodes 25a-25b attached to the front and back of each piezoelectric element 25 (that is, in the thickness direction of the piezoelectric element 25), and one piezoelectric element 25 is extended in the extending direction of the slider holding base 24 and the other By contracting the piezoelectric element 25, the slider holding base 24 is bent toward the contracted piezoelectric element 25, whereby the head slider 21 can be displaced. By attaching the head slider 21 to the gimbal 12a via the actuator 23, it is possible to control fine operations of the head slider 21 that cannot be realized by a voice coil motor, and to cope with a recording medium having a narrowed track pitch. Can do.
[0031]
Then, the effect of this embodiment is demonstrated. The actuator 23 according to the present embodiment has a configuration in which the piezoelectric element 25 is attached to both sides of one slider holding base 24, so that the slider holding base 24 does not generate bending stress due to the pressing force when the piezoelectric element 25 is attached. The distortion of the holding table 24 can be reduced and the reliability of the actuator 23 can be increased. Further, since the slider unit 20 according to the present embodiment is attached to the actuator 23, the accuracy of driving displacement of the head slider 21 can be maintained and the reliability can be improved.
[0032]
Further, according to the manufacturing method of the actuator 23 according to the embodiment, the piezoelectric element 25 is attached to the initially etched flat plate 30, and then the Si frame and the piezoelectric element 25 are cut to cut out the actuator 23. Can be easily manufactured. Further, since the slider holding base 24 is not in a cantilever state, a bending moment is hardly generated even in the cutting process, and distortion of the slider holding base can be reduced.
[0033]
Next, an actuator and a slider unit according to the second embodiment of the present invention will be described. FIG. 6 is a perspective view showing a slider unit 20a according to the second embodiment.
[0034]
The slider unit 20 a according to the second embodiment has the same basic configuration as the slider unit 20 according to the first embodiment, but the slider unit 20 a according to the second embodiment is a gimbal fixing surface of the slider holding base 24. The difference is that a fixing portion 24e is formed. That is, as shown in FIG. 6, in the slider unit 20 a according to the second embodiment, a part of the gimbal fixing surface of the slider holding base 24 is a fixing part 24 e raised from the other part. The position where the fixing portion 24e is formed is the end opposite to the end having the slider mounting portion 24a.
[0035]
In the actuator 23 according to the second embodiment, by having the fixing portion 24e on the gimbal fixing surface, it becomes easy to fix the actuator 23 to the tongue portion 14 of the gimbal. That is, it is easy to fix only a part by applying an adhesive to the fixing part 24e raised from the other part and to separate the other part from the mounting surface (the tongue part 14). As a result, the slider holding base 24 bends smoothly and the head slider 21 is also smoothly displaced. The reason why the fixing portion 24e is provided at the opposite end farthest from the slider mounting portion 24a is to maximize the displacement of the slider mounting portion 24a when the slider holding base 24 is bent.
[0036]
As mentioned above, although the actuator and the slider unit according to the embodiment of the present invention have been described with reference to the embodiment, the present invention is not limited to the above embodiment.
[0037]
In the above embodiment, a piezoelectric element having a single plate structure is taken as an example of the piezoelectric element 25, but a laminated piezoelectric element or a bimorph piezoelectric element may be used. FIG. 7 is an explanatory diagram for explaining the structure of the multilayer piezoelectric element, and shows the internal structure in cross section. A laminated piezoelectric element 40 shown in FIG. 7 is a laminated piezoelectric element including a plurality of piezoelectric ceramic layers 41, a plurality of internal electrode layers 42, and external electrodes 43a and 43b. The piezoelectric ceramic layers 41 and the internal electrode layers 42 are alternately stacked to form a stacked body. Therefore, each piezoelectric ceramic layer 41 is sandwiched between the two internal electrode layers 42. In addition, external electrodes 43a and 43b are provided from the upper surface and the lower surface of the multilayer body to part of the side surfaces, respectively. A surface Sa perpendicular to the stacking direction of the stacked body is an adhesive surface to the slider holding base 24. By using such a laminated piezoelectric element 40, a larger pulling force or contracting force can be applied to the slider holding base 24, so that the maximum displacement amount of the slider holding base 24 can be increased.
[0038]
In the above-described embodiment, the slider unit 20 in which the width of the slider holding base 24 is equal to the width of the slider head 21 has been described. However, as shown in FIG. It may be narrower than the width w4. Thus, by reducing the width w3 of the slider holding base 24, there is an effect that the slider holding base 24 is easily displaced.
[0039]
【The invention's effect】
According to the present invention, since the piezoelectric element is attached to both sides of one slider holding base, bending stress does not occur in the slider holding base even when the piezoelectric element is pressed, so that the slider holding base is not distorted. Thereby, the accuracy of the displacement when the head slider is driven can be maintained, and the reliability of the actuator can be improved.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration example of a head gimbal to which a slider unit according to an embodiment is applied.
FIG. 2 is a perspective view showing a head gimbal assembly according to the embodiment.
FIG. 3 is a perspective view showing a slider unit according to the embodiment.
FIG. 4 is an exploded perspective view of the slider unit according to the embodiment.
FIG. 5 is a diagram illustrating a manufacturing process of the actuator according to the embodiment.
FIG. 6 is a perspective view showing a slide unit according to a second embodiment.
FIG. 7 is a diagram illustrating a configuration of a multilayer piezoelectric element.
FIG. 8 is a diagram showing another example of a slider unit.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Hard disk apparatus, 2 ... Hard disk, 3 ... Spindle, 10 ... Head gimbal assembly, 11 ... Thin-film magnetic head, 12 ... Suspension arm, 12a ... Gimbal, 12b・ ・ ・ Load beam, 14 ... Tung section, 20 ... Slider unit, 21 ... Head slider, 23 ... Actuator, 24 ... Slider holding base, 25 ... Piezoelectric element.

Claims (3)

One slider holding base extending in one direction and having a slider mounting portion for attaching a head slider having a thin film magnetic head formed at one end;
Two piezoelectric elements that are attached to both sides of the slider holding base and extendable in the extending direction of the slider holding base;
Equipped with a,
The slider holding table has a step formed on a recording medium facing surface facing a recording medium to be recorded / reproduced by the head slider, and a side lowered by the step constitutes the slider mounting portion, and is raised by the step. The actuator comprises a piezoelectric element attaching portion for attaching the piezoelectric element . 2. The actuator according to claim 1 , wherein a part of the surface opposite to the recording medium facing surface of the slider holding base is raised. 3. An actuator for mounting a head slider having a thin film magnetic head;
A head slider attached to the slider attachment portion of the actuator;
With
The actuator is
One slider holding base extending in one direction and having a slider mounting portion for attaching the head slider formed at one end;
Two piezoelectric elements that are attached to both sides of the slider holding base and extendable in the extending direction of the slider holding base;
I have a,
The slider holding table has a step formed on a recording medium facing surface facing a recording medium to be recorded / reproduced by the head slider, and a side lowered by the step constitutes the slider mounting portion, and is raised by the step. A slider unit characterized in that the other side constitutes a piezoelectric element mounting portion for mounting the piezoelectric element .

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