JP4752119B2 - Piezoelectric actuator and manufacturing method thereof, and magnetic head using this piezoelectric actuator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a piezoelectric actuator used for, for example, movement of a magnetic head portion in a magnetic recording apparatus, a manufacturing method thereof, and a magnetic head using the piezoelectric actuator.
[0002]
[Prior art]
As a technique related to a conventional piezoelectric actuator for a magnetic head, one disclosed in Japanese Patent Laid-Open No. 5-47126 is known.
[0003]
FIG. 8 is a perspective view showing an example of a conventional actuator for driving a magnetic head. Small displacement elements 81a, 81b, 81c, 81d including a piezoelectric element are bonded to both surfaces of the beams 82a, 82b, and lead wires 84a, 84b, 84c, 84d (84b) are bonded to the respective small displacement elements 81a-81d. , 84d are not shown). The two beams 82a and 82b are joined at both ends, and a slider 83 is attached at one joint, and is attached to the head arm 85 at the other joint. On the slider 83, there are also provided a magnetic head portion for recording and the like and wiring (not shown) thereof.
[0004]
When the minute displacement elements 81a to 81d are piezoelectric elements and electrodes are provided on both surfaces thereof, or when the beams 82a and 82b are made of a conductive material, the lead wires 84a to 84d and the beams 82a and 82b By applying an electric field between the two, the piezoelectric element is deformed. At this time, the piezoelectric element also changes in the longitudinal direction due to the piezoelectric lateral effect simultaneously with the deformation in the thickness direction. The lengths of the beams 82a and 82b also change along with the deformation of the piezoelectric element. If this change occurs in the opposite directions in each of the beams 82a and 82b, that is, the length of one of the beams 82a and 82b increases. In this case, if the drive is performed so that the other is reduced, rotational displacement can be obtained at the magnetic head.
[0005]
These piezoelectric actuators and magnetic heads are usually attached to a magnetic actuator such as a motor that can obtain a larger displacement via another longitudinal member, and positioning is performed by using both of them together. In other words, rough positioning is performed by a motor, and more accurate positioning is performed by a piezoelectric actuator, thereby speeding up positioning and improving accuracy.
[0006]
[Problems to be solved by the invention]
However, since the conventional piezoelectric actuator generally has a small amount of displacement, a high driving voltage is required to obtain a sufficient amount of displacement. Further, in order to obtain a large amount of displacement, when the shape becomes large or the rigidity of the actuator is lowered to facilitate deformation, the resonance frequency is lowered and unnecessary vibration is generated, which hinders driving. In order to be used as an actuator for driving a head of a magnetic recording apparatus, it must be able to move between tracks on a recording medium at a high speed and stably. It must be rigid and must be able to withstand vibrations and gravity from other actuators such as motors.
[0007]
In addition, it is required that a large amount of displacement can be obtained at a low voltage. That is, if the amount of displacement is large, not only can it be moved accurately between tracks, but also the positioning adjustment range can be increased. In order to reduce the size of the circuit and reduce error factors such as noise, driving at a low voltage is required.
[0008]
In order to reduce the size of the entire magnetic recording apparatus, the actuator must be downsized at the same time.
[0009]
An object of the present invention is to provide a small piezoelectric actuator that is more resistant to disturbances and obtains a large amount of displacement, and aims to reduce the size and accuracy of various equipment bodies.
[0010]
[Means for Solving the Problems]
And in order to achieve this objective, this invention has the following structures.
[0011]
According to a first aspect of the present invention, a piezoelectric actuator has two displacement elements, which are a laminate of an elastic flat plate and a piezoelectric body, arranged in parallel and on the same straight line and fixed at one end, and deformation of both displacement elements is performed between both displacement elements. The rotating member that is rotatably supported by is configured in a shape coupled via an L-shaped hinge portion, and rotational displacement is obtained in the rotating member by displacing both displacement elements in opposite directions, The vertical displacement of the displacement element is efficiently converted into a rotational displacement by the L-shaped hinge, and in addition, the displacement is enlarged by the action of the angle and leverage by the rotation, and a larger displacement is obtained. Since the member is supported at the center of rotation and is also fixed by the L-shaped hinge portion, the effect of having high rigidity can be obtained. Further, since the rotation support position is a portion other than the line connecting the joint portion between the L-shaped hinge portion and the rotation member, the rotation member is apparently supported by the apex of the triangle, and the direction other than the rotation direction The effect that the rigidity with respect to the vibration increases is obtained.
[0012]
According to the second aspect of the present invention , a larger displacement amount can be obtained by rotating and supporting the rotating member on the side far from both displacement elements from the straight line connecting the coupling portion with the L-shaped hinge portion. Has an effect.
[0013]
In the third aspect of the invention, since the rotation member is pressed by the protrusion provided on the rotation support member to perform rotation support, the configuration is easy, and the rotation member is only in contact with the tip of the protrusion, so that the friction is low. The effect is that the inhibition of rotational displacement is small .
[0014]
According to the fourth aspect of the present invention , the support member is provided with a support hole, and the protrusion of the rotation support member is fitted into the support hole. The effect of being able to drive is obtained.
[0015]
In the fifth aspect of the invention, the displacement element has a rectangular flat plate shape whose dimension in the width direction perpendicular to the direction is larger than the dimension in the direction of the coupling portion between the fixed portion and the rotating member. With respect to the vertical displacement on the side, a larger driving force can be obtained, and at the same time, the effect of increasing the resonance frequency in the rotational direction can be obtained.
[0016]
In a sixth aspect of the present invention, a process of bending and bonding a piezoelectric body to a large area substrate in which a plurality of elastic flat plates, an L-shaped hinge portion, and a rotating member are arranged in parallel on the same plane is collectively performed. As a result, the productivity can be reduced and the cost can be reduced, and the piezoelectric actuator of claim 1 or less can be easily formed, and the L-shaped hinge portion, the elastic plate, and the rotating member are integrated, so that it is safe. Effects such as excellent reliability and vibration resistance can be obtained.
[0017]
The seventh aspect of the invention is a magnetic head in which a slider and a magnetic head are provided on a rotating member of a piezoelectric actuator. Therefore, since the rigidity is high, the positioning operation on the track is not affected by disturbance and positioning is performed with a large amount of displacement. Thus, the effect is obtained that the positioning on the track can be surely performed .
[0019]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
Hereinafter, the piezoelectric actuator according to the first embodiment of the present invention will be described with reference to the drawings.
[0020]
FIG. 1 is a perspective view of a piezoelectric actuator according to Embodiment 1 of the present invention.
[0021]
In FIG. 1, 11a and 11b are piezoelectric bodies, 12a and 12b are elastic flat plates, 13 is a rotating member, 14a and 14b are L-shaped hinge parts, 15a and 15b are fixing members, 16 is a rotating support member, and 17 is a protruding part. , 18 is a slider. The elastic flat plates 12a and 12b are arranged in parallel and on the same line, and the piezoelectric bodies 11a and 11b are bonded to one side to constitute a displacement element. The elastic flat plates 12a and 12b are fixed at one end by fixing members 15a and 15b, joined to the L-shaped hinge portions 14a and 14b at the other end, and further rotated between the L-shaped hinge portions 14a and 14b. 13 is arranged orthogonal to the plane of the elastic flat plates 12a and 12b, and a part of the rotating member 13 and the L-shaped hinge portions 14a and 14b are coupled to each other. The rotation support member 16 has a longitudinal shape, and a projection 17 is provided in the vicinity of the tip. The tip of the projection 17 abuts the rotation member 13, and the rotation member 13 is appropriately pressed by the rotation support member 16. Then, the tip 17 of the protrusion 17 is pressurized almost at a point. In addition, on one surface of the rotating member 13, the slider 18 is fixed by a method such as adhesion, and is supported in a displaceable state in the same manner as the rotating member 13.
[0022]
Electrodes are provided on both surfaces of the piezoelectric bodies 11a and 11b, respectively. The piezoelectric bodies 11a and 11b are deformed by applying a voltage between both electrodes, and are bonded to the elastic plates 12a and 12b. A deflection displacement occurs at the end portions on the side of the portions 14a and 14b. By reversing the direction of the voltage applied to the piezoelectric bodies 11a and 11b, the displacement element is displaced in the opposite direction. This displacement is transmitted to the rotating member 13 via the L-shaped hinge portions 14 a and 14 b and is rotationally displaced together with the slider 18. This rotational displacement is centered on the point constrained by the protrusion 17, but when the rotating member 13 is pressed by the protrusion 17 as described above, the area, material, etc. of the contact portions of each other It is possible to increase the friction so that the center of rotation can be determined more completely by selecting an appropriate condition, or conversely, the displacement can be increased by reducing the friction. When the rotation center is constrained by increasing the friction, the amount of displacement decreases, but the rigidity as an actuator increases, so that the vibration resistance is improved and a restraint response is possible. And since the displacement by the actuator is a rotational displacement, if the size of the rotating member or slider is increased, the angle change caused by the rotation will be expanded to a large displacement by the lever principle, so the rigidity is improved and the amount of displacement is also secured. It can be done.
[0023]
When the rotation center is constrained, the amount of displacement changes depending on the position. FIG. 2 is a perspective view showing the piezoelectric actuator of the present invention, which is different from FIG. 11a and 11b are piezoelectric bodies, 12a and 12b are elastic flat plates, 13 is a rotating member, 14a and 14b are L-shaped hinge portions, 15a and 15b are fixed members, 18 is a slider, and the structure is described in FIG. It is the same. The rotating member 13 and the elastic flat plates 12a and 12b are connected to each other through the L-shaped hinge portions 14a and 14b. By bringing the rotation center into contact with the rotation support portion on a straight line passing through the center between the character-shaped hinge portions and providing a rotation center, the balance at the time of rotation is improved, so that driving can be performed stably. Therefore, although the center of rotation is provided on the straight line, the amount of rotational displacement changes depending on this position. When the center of rotation is provided on the side farther from the straight line connecting the centers of the L-shaped hinge portions 14a and 14b with respect to the elastic plates 12a and 12b and the piezoelectric bodies 11a and 11b, the elastic plates 12a and 12b and the piezoelectric bodies 11a are reversed. , 11b, the amount of displacement is larger than that provided on the side close to 11b. However, even when the rotation center is set on the far side, the amount of displacement changes, and the frequency of resonance in the same direction as the rotational displacement, the frequency of other unnecessary resonances, and the like also change. This is because the optimum position changes depending on the shape of the L-shaped hinge portion, the coupling position with the rotating member, and the like, and therefore, the optimum position is determined in consideration of these points.
[0024]
In the present invention, an L-shaped hinge is used, which is effective for obtaining rotational displacement. FIGS. 3A and 3B are plan views for explaining this point. 11a and 11b are piezoelectric bodies, 12a and 12b are elastic flat plates, 14a and 14b are L-shaped hinge portions, 15a. 15b are fixed members, 18 is a slider, 19 is a rotation support portion, and 20a and 20b are linear hinge portions (rotation members are omitted). In FIG. 3 a, linear hinge portions 20 a and 20 b are located between the elastic plates 12 a and 12 b and the slider 18. In this case, the displacement of the displacement element (unimorph type element) constituted by the piezoelectric bodies 11a and 11b and the elastic plates 12a and 12b is as shown by the solid line arrow, and is substantially perpendicular to the displacement element surface. The displacement is transmitted to the slider 18 by the linear hinge portions 20a and 20b, and the displacement is performed in the same direction as the solid line arrow as shown by a dotted line arrow. On the other hand, when the L-shaped hinge portion is used as shown in FIG. 3B, the displacement as indicated by the solid line arrow is apparently converted into the oblique direction as indicated by the dotted line arrow. This is because the hinge portion is L-shaped, so that deflection is likely to occur, and this deflection is due to the effect of changing the direction of displacement. Further, by using the deflection of the L-shaped hinge portion, the slider is not restrained more than necessary, and the displacement is effectively transmitted. If the direction of the dotted arrow is close to the tangential direction of the rotational displacement, the rotational displacement can be obtained effectively.
[0025]
FIG. 4 is a cross-sectional view showing an example for more effectively carrying out rotation support, wherein 13 is a rotation member, 16 is a rotation support member, 17 is a protrusion, 18 is a slider, and 21 is a support hole. The rotating member 13 is provided with a support hole 21 that is a through hole, and is coupled to the slider 18. For example, a magnetic head portion is provided in the vicinity of one end of the slider 18 when used as a head for a magnetic recording apparatus. The protrusion 17 provided on the rotation support member 16 presses the slider 18 while fitting into the support hole 21. According to such a configuration, the position of the rotation center can be easily determined, there is no fear that the rotation center is shifted during driving, and the position of the rotation center is prevented from being displaced due to external vibrations, etc. Since it also functions as a stopper against a load applied from the vertical direction of the drawing of FIG. 4, it is possible to prevent the actuator from being damaged.
[0026]
FIG. 5 is a perspective view showing an example in which the piezoelectric actuator of the present invention is used as an actuator for driving a magnetic head for a magnetic recording apparatus. In FIG. 5, 15 is a fixing member, 16 is a rotation support member, 18 is a slider, 22 is a piezoelectric actuator section, 23a and 23b are head wiring patterns, 24 is head wiring, and 25 is a recording medium. As described above, the piezoelectric actuator unit 22 is composed of a displacement element composed of an elastic flat plate and a piezoelectric body, an L-shaped hinge unit, and a rotating member. The piezoelectric actuator unit 22 is fixed by a fixed member 15, and a slider 18 is provided on the movable unit. . As shown in FIG. 4, the slider 18 is provided with a magnetic head portion, and in addition, a wiring pattern for applying a signal to the magnetic head portion. The fixing member 15 is formed by processing a single plate-like member, provided with a groove for disposing the actuator portion 22 at the tip, and having a portion molded at a right angle by bending at the tip. The elastic flat plate of the actuator part 22 is fixed to this part. Head wiring patterns 23a, 23b are formed on one surface of the fixing member 15 so as to be electrically insulated from the fixing member 15. The head wiring patterns 23a, 23b and the magnetic field on the slider are formed. A wiring pattern for the head portion is connected via the head wiring 24. Also, an actuator wiring pattern (not shown) for driving the piezoelectric actuator section 22 is formed on the other surface of the fixing member 15, and an external wiring extraction section (not shown) is formed together with the head wiring patterns 23a and 23b. ). Further, the rotation support member 16 is fixed to the fixed member 15, and a part of the piezoelectric actuator portion 22 is pressed to form a rotation center. In this state, the slider 18 is disposed so as to float on the recording medium 25 when the recording medium 25 rotates, and the vicinity of the other end of the fixing member 15 is attached to another large displacement actuator.
[0027]
In order to quickly perform rough positioning on a rotating recording medium, the fixed member is rotated by a large displacement actuator such as a motor, and the slider is rotated by the piezoelectric actuator unit to perform accurate positioning. . When the actuator is moved by the large displacement actuator, the slider or the piezoelectric actuator portion receives an external force. When the rigidity of the piezoelectric actuator is low, distortion occurs or the driving force is inferior to the external force, so that accurate positioning cannot be performed. However, according to the piezoelectric actuator of the present invention, since it has both high rigidity and a large amount of displacement, positioning in a wider range is possible without being affected by external force. As a result, the recording speed of the magnetic head is improved, and the actuator is small, so that the entire apparatus is not large, and can contribute to miniaturization and high performance.
[0028]
FIG. 6 is a perspective view showing an example of a fixing method and a wiring extracting method when the piezoelectric actuator of the present invention is used as a magnetic head driving actuator. In FIG. 6, 11 is a piezoelectric body, 12 is an elastic plate, 14 is an L-shaped hinge, 15 is a fixing member, 26 is an upper electrode pattern, 27 is a lower electrode pattern, 28a and 28b are actuator wirings, and 29 is an actuator. Wiring pattern. The overall configuration is substantially the same as described above, and the elastic flat plate 12 is fixed to the fixing member 15 by welding. That is, the fixing member 15 and the elastic flat plate 12 are, for example, metal plates, the electrodes on both sides of the piezoelectric body 11 are patterned, and one part thereof is provided with the upper electrode pattern 26 and the lower electrode pattern 27, and the welded portion is formed of these electrode patterns. It becomes the removed part. Each electrode pattern has a resin layer at the interface with the elastic flat plate 12, and electrical insulation is maintained. The upper electrode pattern 26 has a layer of piezoelectric material in the lower portion thereof, and ensures insulation from the lower electrode. An actuator wiring pattern 29 is provided on the fixing member 15, and is further connected to the outside through the surface of the fixing member 15. The actuator wiring pattern 29, the upper electrode pattern 26, and the lower electrode pattern 27 are provided. They are electrically connected via the actuator wirings 28a and 28b. By applying a voltage between the upper electrode and the lower electrode in this state, a displacement can be generated in the displacement element made of the piezoelectric body and the elastic plate.
[0029]
Although the movable part of the displacement element has a rectangular shape, the displacement element is orthogonal to the direction rather than the dimension in the direction of the coupling part between the fixed part and the rotating member, that is, the lateral dimension in the drawing. By making the rectangular plate shape with a large dimension in the width direction, that is, in the vertical direction in the drawing, a larger driving force can be obtained with respect to the displacement on the free end side, and at the same time, the resonance frequency is increased. In addition, the vibration resistance is improved. Although this method usually reduces the amount of displacement, the piezoelectric actuator of the present invention converts the vertical displacement into a rotational displacement, which has the effect of enlarging the displacement by rotation, thus avoiding such a problem, and at the same time, having high rigidity in the piezoelectric actuator. It becomes possible to have.
[0030]
(Embodiment 2)
Hereinafter, the piezoelectric actuator according to the second embodiment will be described with reference to the drawings.
[0031]
FIG. 7 is a diagram showing a method for manufacturing a piezoelectric actuator in the second embodiment of the present invention.
[0032]
In FIG. 7, 11a and 11b are piezoelectric bodies, 12a and 12b are elastic plates, 13 is a rotating member, 14a and 14b are L-shaped hinges, 26a and 26b are upper wiring patterns, and 27a and 27b are lower wiring patterns. It is. In FIG. 7 (a), a plurality of constituent members of one actuator including elastic flat plates 12a and 12b, a rotating member 13, and L-shaped hinge portions 14a and 14b are provided in parallel to the same elastic flat plate. Yes. This can be formed, for example, by etching one wide metal plate. Next, as shown in FIG. 7 (b), bending is performed at one part of the L-shaped hinge portions 14a and 14b, and the L-shaped hinge portions 14a and 14b and the rotating member 13 are integrally formed with the elastic flat plate 12a, It is made orthogonal to 12b. Subsequently, the piezoelectric bodies 11a and 11b on which the upper electrode patterns 26a and 26b and the lower electrode patterns 27a and 27b are formed in advance are bonded to the elastic flat plates 12a and 12b, and the state shown in FIG. 7C is obtained. Thereafter, each piezoelectric actuator is divided and fixed to another fixing member or the like to complete.
[0033]
According to the method as described above, the piezoelectric actuator can be easily formed, and a plurality of piezoelectric actuators can be manufactured on one substrate, so that workability is good. For example, positioning such as bonding and bending can be performed all at once, and bonding can be performed all at once by using an adherend having a large area. In addition, handling of fine members can be easily performed as a whole on the entire substrate.
[0034]
In this embodiment, the piezoelectric body is bonded after the bending process. However, even if the piezoelectric body is bonded before the bending process, the advantages of the present invention are not lost. In addition, the upper and lower wiring patterns have already been formed in this embodiment before bonding. However, the upper and lower wiring patterns are patterned after bonding the piezoelectric body having no wiring pattern prior to bending. It can also be formed by a method of performing bending and subsequently bending.
[0035]
【The invention's effect】
As described above, the present invention comprises a laminated body of an elastic flat plate and a piezoelectric body, and is provided with a pair of displacement elements arranged in parallel and on the same line, and an L-shaped hinge portion between the displacement elements. Since the rotating member that is rotatably supported by the deformation of the both displacement elements and the opposite side of the displacement element to the rotating member side are fixed by the fixing member, it has both high rigidity and a large amount of displacement. A small piezoelectric actuator can be realized. And the rotation support with respect to a rotation member can be easily implement | achieved by methods, such as pressing with a protrusion-shaped member or fitting with the support hole provided in the rotation member. Then, a substrate in which the integrated L-shaped hinge portion and the rotating member and the elastic plate are arranged on the same plane is formed, and the rotating member and the L-shaped hinge portion are integrated with the substrate with respect to the elastic plate. According to the manufacturing method in which the piezoelectric body is bent at a right angle and the piezoelectric body is bonded to the elastic flat plate, the piezoelectric actuator of the present invention having the L-shaped hinge portion and the rotating member can be easily and integrally realized. Productivity is good because batch processing is possible.
[0036]
By using the piezoelectric actuator of the present invention as an actuator for positioning a magnetic head, it is possible to reduce the size of the device because it is small, and it is possible to stably record information and to respond at high speed because of excellent vibration resistance. Therefore, the recording speed can be increased, and in addition, since the displacement is large, the positioning adjustment width can be increased, so that the positioning becomes easier.
[Brief description of the drawings]
1 is a perspective view of an actuator according to a first embodiment of the present invention. FIG. 2 is a perspective view of the actuator. FIG. 3A is a plan view of the actuator. FIG. 1B is a plan view of the actuator. FIG. 5 is a perspective view of a magnetic head as a main part and a peripheral part thereof. FIG. 6 is a perspective view of the main part. FIG. 7 is an actuator according to a second embodiment of the invention. Manufacturing process diagram [Fig. 8] Perspective view of conventional actuator [Explanation of symbols]
11a, 11b Piezoelectric bodies 12a, 12b Elastic flat plate 13 Rotating members 14a, 14b L-shaped hinge portions 15a, 15b Fixed member 16 Rotating support member 17 Protruding portion 18 Slider

Claims (7)

  It consists of a laminate of an elastic flat plate and a piezoelectric body, and is rotated by deformation of a pair of displacement elements arranged in parallel and on the same line, and both displacement elements provided between the displacement elements via an L-shaped hinge. A rotating member that is supported and a side opposite to the rotating member side of the displacement element are fixed by a fixing member, and the rotating member is a combination of the pair of L-shaped hinge portions and the rotating member. Piezoelectric actuator that is rotatably supported at a position away from the straight line connecting the parts.   A rotation support member that supports the rotation member is provided, and a portion that is rotatably supported by the rotation support member is farther than a displacement element with respect to a straight line that connects the coupling portion between the rotation member and the pair of L-shaped hinge portions. The piezoelectric actuator according to claim 1 provided at a position.   The piezoelectric actuator according to claim 2, wherein the rotation support member includes a protrusion, and the rotation member is supported by the protrusion.   The piezoelectric actuator according to claim 3, wherein the rotation member includes a support hole that fits and supports the protrusion of the rotation support member. Elastic flat plate exposed from the fixing member, the dimension in the direction from the fixed member toward the rotating member, a piezoelectric actuator according to a small claim 1 than the dimension in the width direction orthogonal to these.   A substrate in which the L-shaped hinge portion and the rotating member integrated with the elastic plate are arranged on the same plane is formed, and the rotating member and the L-shaped hinge portion are integrated with the substrate at a right angle to the elastic plate. The method for manufacturing a piezoelectric actuator according to claim 1, wherein the piezoelectric body is bonded to the elastic flat plate by bending the substrate into an elastic plate.   It consists of a laminate of an elastic flat plate and a piezoelectric body, and is rotated by deformation of a pair of displacement elements arranged in parallel and on the same line, and both displacement elements provided between the displacement elements via an L-shaped hinge. The rotating member that is supported and the side opposite to the rotating member side of the displacement element are fixed by a fixing member, and the rotating member is connected to a connecting portion between the pair of L-shaped hinge portions and the rotating member. A magnetic head comprising a piezoelectric actuator rotatably supported at a position away from a straight line, a slider fixed to a rotating member of the piezoelectric actuator, and a magnetic head provided on the slider.

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