JP4369597B2 - Piezoelectric actuator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a piezoelectric actuator that is used to move and position an object or change the course of a fluid by being accompanied by a spatially small displacement with a high degree of freedom, and more particularly to a monolithic piezoelectric actuator.
[0002]
[Summary of Invention]
The present invention relates to a monolithic piezoelectric actuator having a configuration that enables a highly accurate bending operation without using any of a unimorph structure and a bimorph structure, and a hybrid structure so that a complicated operation can be performed. A large number of electrodes with the shape, size, and relative position for the desired operation are placed on the opposing faces of a monolithic plate-shaped piezoelectric material with a small number of parts. By connecting to a switch circuit that can be connected to a DC power supply and changing the state of the electric field generated during polarization and driving, the entire shape of the expansion / contraction operation, bending operation and rotation operation can be performed with high accuracy, and the shape of the piezoelectric material And control posture.
[0003]
[Prior art]
Piezoelectric actuators using the inverse piezoelectric effect of piezoelectric materials are said to be unsuitable for actuators with large displacements due to their strength and displacement generation efficiency, but they require minute displacements of several nanometers to several millimeters. It has been applied to the purpose.
[0004]
In the inverse piezoelectric effect, for example, when distortion occurs in a direction extending perpendicularly to the electrode, the volume of the piezoelectric material does not change, so that a phenomenon of contraction occurs in the lateral direction. In particular, many use the displacement due to this expansion and contraction. That is, the amount of displacement is increased by laminating a piezoelectric material to which an electrode for providing the same function is used as it is or using the stretch and contraction as it is.
[0005]
The laminated type is applied in various fields because the generated force is large and the amount of displacement can be controlled by the number of laminated layers. Usually, it is designed to utilize the displacement in the extension direction, but there are some that can perform a bending operation (for example, Japanese Patent Laid-Open No. 5-261610). The actuator described in Japanese Patent Application Laid-Open No. 5-26161 is a laminate of disk-shaped unimorph elements. Focusing on one layer, each pair of electrodes divided into a large number is arranged on a disk, and distortion is generated by applying a voltage to each pair of electrodes. Is possible.
[0006]
On the other hand, unimorph type and bimorph type actuators are known for the purpose of bending operation and turning operation (rotating operation). The unimorph type has a structure in which one piezoelectric material having symmetrical electrodes on the front and back surfaces is laminated on one elastic body by bonding or the like. The bimorph type is an arrangement in which an elastic body is sandwiched between two piezoelectric materials having symmetrical electrodes on the front and back surfaces in order to increase the amount of bending.
[0007]
Japanese Patent Application Laid-Open No. 5-318373 proposes an actuator having a high degree of freedom by applying a unimorph type or bimorph type actuator. Japanese Patent Application Laid-Open No. 11-206149 proposes an integrated actuator that does not require an assembly process such as assembly or adhesion required for a unimorph or bimorph actuator. The actuator described in Japanese Patent Application Laid-Open No. 11-206149 uses a comb-shaped electrode in order to use the longitudinal effect of the inverse piezoelectric effect, and further applies a substrate that controls expansion and contraction by the normal inverse piezoelectric effect in order to promote bending. It has a laminated structure by printing, thick film / thin film technology, etc.
[0008]
In applications that do not require a large generated force or displacement, the generated force or displacement of only one layer constituting the stack may be sufficient. For example, there is an example in which a space is provided in the structure body and two hinges are arranged, and the structure body is displaced in the lateral direction (X-axis) by using an expansion / contraction operation of each of the two hinges.
[0009]
At this time, if the generated force and displacement of an actuator made of a single plate-like or bulk-like piezoelectric material are sufficient in terms of performance, such a piezoelectric material is processed and electrodes are arranged only at the necessary portions. This monolithic structure is an excellent process in terms of reducing assembly and wiring processes, reducing manufacturing accuracy, and reducing costs.
[0010]
Further, regarding sensors and actuators using a piezoelectric material, there is hysteresis between an applied voltage and displacement or strain. In Japanese Patent Laid-Open No. 5-56667, electrodes arranged in a piezoelectric material are subdivided, and in particular, displacement Proposal has been made for a method that can stably obtain a fine-precision displacement, avoiding the use in a low voltage region where the characteristics are unstable and cause a displacement error. In this case, the electrode is finely divided to achieve both accuracy and displacement with respect to displacement in the expansion / contraction direction.
[0011]
[Problems to be solved by the invention]
As described above, conventionally, a unimorph or bimorph type actuator using an elastic body in order to perform a bending operation or a twisting operation (rotating operation) using a piezoelectric actuator has been mainly used. However, since these have a hybrid structure using a plurality of materials such as a piezoelectric material and an elastic body, the cost is higher than a monolithic structure piezoelectric actuator using only a single piezoelectric material.
[0012]
In addition, the number of electrodes that can be controlled independently is as small as two or two and the displacement and bending operation angles are controlled only by the voltage applied to these electrodes, so that it is difficult to perform complicated posture control.
[0013]
An object of the present invention is to provide a piezoelectric actuator capable of performing a bending operation and a complicated posture control with higher accuracy than those of a hybrid structure using a monolithic plate-shaped piezoelectric material.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, the piezoelectric actuator of the present invention opposes a monolithic plate-shaped piezoelectric material. Front and back Each of Placed in a mutually insulated state Multiple electrodes with shape, size and relative position for desired operation When, Switch circuit capable of independently connecting a plurality of electrodes to a DC power source And Prepared, By the switch circuit A control for connecting each of the plurality of electrodes independently to a positive electrode or a negative electrode of the DC power supply; Or By performing control that is not connected to either, Creates an arbitrary polarization state by changing the direction and magnitude of the electric field during polarization generated between the electrode connected to the positive electrode and the electrode connected to the negative electrode. By changing the direction and magnitude of the electric field generated between the electrode and the driving electrode, It is characterized in that all or a part of the expansion / contraction operation, bending operation, and rotation operation is performed in the arrangement region of the multiple electrodes.
[0015]
In the piezoelectric actuator of the present invention, the plate-like piezoelectric material is formed in a rectangular shape, and the multiple electrodes are arranged in an array on substantially the entire front or back surface or a specific region.
[0016]
In the piezoelectric actuator of the present invention, the rectangular plate-shaped piezoelectric material has one end side as a fixed portion, and the plurality of electrodes are arranged in an array on the front and back surfaces on the other end side. It is said.
[0017]
Furthermore, in the piezoelectric actuator of the present invention, the plate-like piezoelectric material is formed in a disc shape, and the multiple electrodes are concentrically arranged on the front and back surfaces.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a configuration diagram of a piezoelectric actuator according to an embodiment of the present invention. As shown in FIG. 1, in this piezoelectric actuator, a large number of electrodes 2a to 2i and 3a to 3i are arranged symmetrically in an array on the front and back surfaces of a monolithic piezoelectric plate member 1, and the respective electrodes are connected to switches 4a to 4i and These are individually connected to the DC power source 6 through corresponding switches 5a to 5i. In the following description, the electrodes 2a to 2i may be referred to as an electrode group 2 and the electrodes 3a to 3i may be referred to as an electrode group 3 as appropriate.
[0019]
These electrodes are formed on the front and back surfaces of the piezoelectric plate 1 by dip coating, spray coating, spin coating, printing, spucking, vapor deposition, plating, electrophoresis, or a plurality of means, and photolithography, dicing, and laser processing. -Shaped into a plurality of arrays by any one of polishing, grinding, application, ashing, or a plurality of means.
[0020]
In addition, as can be understood from the various examples described below, the piezoelectric plate material 1 can be shaped according to the purpose, such as a rectangular plate shape or a disk shape. The relative positions of the arrayed electrodes may be any positional relationship as long as they are not in electrical contact with each other. Arbitrary arrangements can be made according to the purpose of operation.
[0021]
In the above configuration, the arrayed electrodes are independently connected to the positive electrode or the negative electrode of the DC power source 6 through the switches 4a to 4i and 5a to 5i, or are not connected to any of them.
[0022]
Therefore, by turning these switches on and off independently, the connection state and polarity of the electrodes are controlled independently, and the electric field during polarization generated between the electrode connected to the positive electrode and the electrode connected to the negative electrode The direction and size of can be varied to create an arbitrary polarization state.
[0023]
In addition, by independently turning on and off the switches connected to the array electrode, the connection state and polarity of the array electrode are controlled independently, and generated between the positive electrode and the negative electrode The direction and magnitude of the electric field during driving is varied, and as a result, the degree of expansion / contraction due to distortion generated in the piezoelectric plate material 1 having a monolithic structure is adjusted, and the expansion / contraction operation, single or plural bending operations, and single or plural operations are performed. Can be rotated.
[0024]
Next, the confirmation result of the above operation will be described with reference to FIGS. FIG. 2 is a side view showing a specific dimension example of the piezoelectric actuator manufactured for checking the operation. FIG. 3 is a perspective view showing a specific appearance and dimension example. As shown in FIGS. 2 and 3, the piezoelectric plate 1 was formed in a rectangular shape having a length of 15 mm, a width of 2 mm, and a thickness of 0.5 mm. A section of the piezoelectric plate 1 of 5.5 mm from the left end in FIG. 2 is the measurement fixing portion 1a, and a section of 9.5 mm from the right end to the right end is the electrode forming region 1b. In this electrode formation region 1b, a chromium gold electrode (electrode group 2 and electrode 2) having a length of 2 mm, a width of 800 μm, and a thickness of 400 nm is formed on the front and back surfaces of the remaining 8.5 mm region with a space of 0.5 mm at both ends. Group 3) was produced symmetrically at 1 mm pitch.
[0025]
FIG. 4 is an explanatory diagram of the formation of the electric field strength distribution inside the piezoelectric plate 1. It should be noted that the electric field strength distribution in the piezoelectric plate material 1 is actually the composition distribution, piezoelectric constant, polarization strength, polarization direction, operating electric field strength distribution, operating electric field direction, etc. Although it is complicated because there is a complicated correlation between them, it is simplified in FIG.
[0026]
In FIG. 4, first, all the switches 4a to 4i and 5a to 5i are closed and energized, the electrodes 2a to 2i are connected to the positive electrode of the DC power source 6, and the electrodes 3a to 3i are connected to the negative electrode of the DC power source 6. The piezoelectric plate material 1 was polarized by applying a DC voltage of 600 V between the electrode group 2 and the electrode group 3 for 30 seconds to generate a DC electric field of 1 kV / mm macroscopically. Therefore, it is considered that a polarization electric field (initial polarization electric field) 7 is generated in the piezoelectric plate member 1 perpendicular to the front and back surfaces and from the front surface to the back surface.
[0027]
Thereafter, the switch is switched so that only selected electrodes of the electrode group 2 and the electrode group 3 can be energized, and an electric field of 200 V / mm is applied between the selected electrode group 2 and the electrode group 3 in the same direction as during polarization. I tried to work. At this time, it seems that an electric field intensity distribution state different from that during polarization occurs.
[0028]
For example, as shown in FIG. 4, in the electrode group 2, the switches 4a to 4c are closed and the electrodes 2a to 2c are connected to the positive electrode of the DC power source 6, and in the electrode group 3, the switch 5b is closed and the electrode 3b is connected to the DC power source 6. An electric field of 200 V / mm was applied to the negative electrode. In this case, as shown in FIG. 4, it is considered that an electric field (operation electric field) from the three electrodes 2a to 2c toward the one electrode 3b is generated.
[0029]
FIG. 5 is an explanatory diagram of displacement measurement. As shown in FIG. 5, the measurement fixing portion 1 a having a length of 5 mm where no electrode is arranged was fixed to the clamp 10, and the displacement of the tip portion on the opposite side was measured. A bending operation was caused by the electrode selection pattern, and a displacement of 3.0 μm in the vertical direction was confirmed at the tip.
[0030]
FIG. 6 is an explanatory diagram of the attitude control operation. Similarly to FIG. 5, when the measurement fixing portion 1 a having a length of 5 mm where no electrode is arranged is fixed and the posture control is performed to translate the tip on the opposite side, the displacement is 1.7 μm. confirmed. For the measurement of displacement, a laser microscope and a surface roughness measuring instrument are used after being modified.
[0031]
FIG. 7 is an explanatory diagram of the rotating operation. (A) is a non-operation state diagram, (b) is an operation state diagram. In FIG. 7B, the electrodes are not shown. Similarly to FIG. 5, a 5 mm long portion where no electrode is disposed is fixed (FIG. 7A). Due to the electrode selection pattern, a bending operation occurred, and the rotation of the tip on the opposite side could be performed (FIG. 7B).
[0032]
Example 1
FIG. 8 is a diagram illustrating a usage example (Example 1) of the piezoelectric actuator according to the present embodiment. In a disk recording / reproducing apparatus using an HDD or a slider-type optical head, an actuator that realizes tracking and space control (focusing) with high accuracy while maintaining a posture is required.
[0033]
FIG. 8 shows an example in which the disk apparatus is used as an actuator for adjusting the space height with a rotating disk while maintaining the posture of the slider.
[0034]
In FIG. 8, the attitude control spacing control actuator 20 is a piezoelectric actuator according to the present embodiment, a portion where no electrode is arranged is fixed to a support column 21, and an opposite electrode formation region extends on the disk 22. Is retained. A slider 23 is fixed to the lower surface of the tip of the electrode formation region.
[0035]
In a state before the disk 22 is rotationally driven by the disk rotating motor 24 or in an initial driving state, the slider 24 is spaced above the disk 22 by a space 25 as shown in FIG. The disk 22 is supported in parallel.
[0036]
In this state, by causing the attitude control spacing control actuator 20 to perform the above-described vertical displacement operation and attitude control operation, the slider 24 has a space above the disk 22 as shown in FIG. A space 26 with an interval smaller than the interval of 25 can be placed parallel to the surface of the disk 22 and maintained.
[0037]
Thus, the piezoelectric actuator according to the present embodiment can be used as an actuator for moving and positioning the sensing device.
[0038]
Example 2
FIG. 9 is a diagram illustrating a usage example (Example 2) of the piezoelectric actuator according to the present embodiment. FIG. 9 shows an example of use as a tracking actuator that can also control the protrusion amount of a magnetic head used in a broadcast digital VTR or the like.
[0039]
In FIG. 9A, the magnetic head 32 is slidably contacted with the magnetic tape 31 that is driven to drive, and signals are recorded and reproduced. As shown in the enlarged view, the magnetic head 32 is attached to the tip of the tracking actuator 33 in the VTR drum 30 so that it protrudes from the peripheral surface of the VTR drum 30 and can slide on the magnetic tape 31.
[0040]
In FIG. 9B, in the VTR, the track on which normal magnetic information recording / reproduction is performed by the magnetic head 32 should be a straight line like the track 35, but actually, the track is bent like the track 36. There are many. If this bend becomes larger than the track width, an undesirable phenomenon occurs such as overwriting the track written immediately before at the time of recording, or failure to read the recorded signal correctly at the time of reproduction.
[0041]
In order to prevent this, the control of the position of the magnetic head 32 to be the correct track position is referred to as tracking. By sensing the bending state of the track at the time of recording or reproduction, the information of the magnetic head 32 is fed back. The method of actively controlling the position is called dynamic tracking.
[0042]
Conventionally, a bimorph type piezoelectric actuator is often used for this position control, and in a VTR with a dynamic tracking function (FIG. 9A), a tracking deviation of about several μm (FIG. 9B) is corrected. Thus, the position control of the magnetic head 32 is performed.
[0043]
At this time, conventionally, the attitude control is performed so that the contact angle between the magnetic tape 31 and the magnetic head 32 does not change greatly from the normal state. However, since the total length of the tracking actuator 33 does not change, for example, FIG. As shown in FIG. 4, depending on the degree of attitude control, a state (b) indicated by a broken line where the magnetic head 32 can contact the magnetic tape 31 and a state (b) indicated by a solid line where the magnetic head 32 cannot contact are generated. A space 37 is generated between the two. Such a space 37 is said to lead to deterioration of the SN ratio at the time of recording / reproducing magnetic signals.
[0044]
Therefore, since the piezoelectric actuator according to the present embodiment can be expanded and contracted, if the piezoelectric actuator according to the present embodiment is used as the tracking actuator 33, the magnetic head 32 is controlled by posture control as shown in FIG. The magnetic head 32 can be brought into contact with the magnetic tape 31 in both states even when the position moves from the state indicated by the broken line (c) to the state indicated by the solid line (d).
[0045]
In other words, by using the piezoelectric actuator according to the present embodiment, in addition to the tracking operation and the attitude control operation, an operation (head protrusion amount control) can be performed to prevent the generation of this space. It is possible to prevent the SN ratio from being deteriorated due to the occurrence of a space between them.
[0046]
Example 3
FIG. 10 is a diagram illustrating a usage example (Example 3) of the piezoelectric actuator according to the present embodiment. FIG. 10 shows that the present invention can be applied to a manipulator of an apparatus such as AFM (Atomic Force Microscopy) that requires high-precision micropositioning for observing a microregion. FIG. 10A is a configuration diagram of a conventional AFM sensing unit. FIG.10 (b) is a block diagram of the cantilever and manipulator by this Embodiment.
[0047]
In FIG. 10A, the AFM sensing unit has a sensor unit 43 called a tip attached to the tip of a cantilever 42 supported by a manipulator 41. In this AFM sensing unit, the manipulator 41 can accurately move the cantilever 42 in the X-axis direction 44, the Y-axis direction 45, and the Z-axis direction 46, thereby sensing the observation target 47 in a specific region. Currently, the manipulator 41 is a bimorph type or a unimorph type.
[0048]
In FIG. 10B, a cantilever 51 according to the present embodiment is formed of a monolithic piezoelectric plate material formed in a rectangular plate shape, and an electrode group 52 is formed on the front and back surfaces of the substantially middle portion in the longitudinal direction. . One end in the longitudinal direction is a fixed portion 53, and the sensor portion 43 described above is attached to the other end which is a free end.
[0049]
By applying a voltage to the electrode group 52 as described above, the cantilever 51 can be moved in the X-axis direction 54, the Y-axis direction 55, and the Z-axis direction 56 with high accuracy. Sensing can be performed.
[0050]
In this way, by combining a cantilever and a manipulator, it is possible to realize an actuator that can be easily scanned with a small number of parts and at a low cost. Although not shown, the piezoelectric actuator according to the present embodiment can be used as the manipulator 41 for operating the conventional cantilever 42 as a matter of course.
[0051]
Example 4
FIG. 11 is a diagram illustrating a usage example (Example 4) of the piezoelectric actuator according to the present embodiment. FIG. 11 shows that a relay switch can be configured by using both the expansion and contraction operation and the bending operation of the piezoelectric actuator according to the present embodiment. (A) is a block diagram and (b) and (c) are operation explanatory diagrams.
[0052]
In FIG. 11A, electrodes 62 formed on both surfaces of a rectangular piezoelectric plate material 61 are connected to a DC power source by a wiring 63 via a switch circuit (not shown). That is, the piezoelectric actuator itself according to the present embodiment shown in FIG. 1 is directly configured, and in the drawing, the lower end is a fixed portion, and the region where the electrode 62 shown in the figure is formed is a free end.
[0053]
A switch electrode 64 is attached to the free end of the piezoelectric plate material 61. A large number of relay contacts 65a to 65 (c) are arranged on the left side of the switch electrode 64 in the vertical direction along the piezoelectric plate member 61, and a large number of relay contacts 65a to 65 (c) are also symmetrical in the vertical direction on the right side. Is arranged. A signal line 66 to be switched is connected to the switch electrode 64.
[0054]
With this configuration, the electrode 62 forming portion of the piezoelectric plate material 61 performs an expansion / contraction operation and a bending operation, whereby the switch electrode 64 is displaced in the vertical direction and the horizontal direction to select a large number of relay contacts (65a to 65f). In contact with the signal line 66.
[0055]
For example, in the illustrated example, since the switch electrode 64 is located at the position where the relay contact 65 (b) (e) is disposed, as shown in FIG. 11 (b), the piezoelectric plate member 61 is bent to the right without being expanded or contracted. The switch electrode 64 can be brought into contact with the relay contact 65 (e) simply by performing the above. Similarly, the switch electrode 64 can be brought into contact with the relay contact 65 (b) only by causing the piezoelectric plate member 61 to perform an operation of turning to the left without causing an expansion / contraction operation.
[0056]
Further, as shown in FIG. 11C, the switch electrode 64 can be brought into contact with the relay contact 65 (c) by causing the piezoelectric plate member 61 to perform a contracting operation and a left-turning operation. Similarly, the switch electrode 64 can be brought into contact with the relay contact 65f by causing the piezoelectric plate member 61 to perform a contracting operation and a right-turning operation.
[0057]
Although not shown in the drawing, the piezoelectric plate member 61 is caused to perform an extending operation and bend to the left so that the switch electrode 64 is brought into contact with the relay contact 65a and is bent to the right. 64 can be brought into contact with the relay contact 65 (d).
[0058]
As described above, the expansion / contraction operation and the bending operation of one piezoelectric actuator can select and individually operate a large number of relay contacts constituting the relay switch.
[0059]
Example 5
FIG. 12 is a diagram illustrating a usage example (Example 5) of the piezoelectric actuator according to the present embodiment. FIG. 12 shows that a microvalve that adjusts the flow rate of fluid can be configured by using the bending operation of the piezoelectric actuator according to the present embodiment. (A) is a block diagram, (b) is operation | movement explanatory drawing.
[0060]
In FIG. 12A, a bending operation piezoelectric actuator 72 is disposed inside the housing 71. The casing 71 is provided with a fluid inlet 73 for taking in the fluid 75 at the upper right side and a fluid outlet 74 for discharging the fluid 75 at the upper left side.
[0061]
Next, the operation will be described. In FIG. 12B, the fluid discharge port 74 is blocked by the bending actuator 72, and the fluid 75 is taken in from the fluid inlet 73 (S1). When the bending operation actuator 72 is flattened, the inside of the casing 71 is filled with the fluid 75 (S2). When the bending operation is increased while the bending operation actuator 72 blocks the fluid inlet 73, the fluid 75 is discharged from the fluid discharge port 74 (S3). The principle of the microvalve can be applied to an injector or the like.
[0062]
Example 6
FIG. 13 is a diagram illustrating a usage example (Example 6) of the piezoelectric actuator according to the present embodiment. FIG. 13 shows that a plurality of piezoelectric actuators according to the present embodiment can be used as an adjustment device for force transmission efficiency of a fluid clutch by causing a waving operation like a wing. (A) is a perspective view which shows a structure, (b) is side sectional drawing which shows a structure, (c) (d) is operation | movement explanatory drawing.
[0063]
13A and 13B, bending motion piezoelectric actuators 82 are embedded and arranged in an array (5 × 2 in the illustrated example) on the surface of an arbitrary structure 81. Each bending motion piezoelectric actuator 82 is formed with electrodes on almost the entire front and back surfaces of a rectangular piezoelectric plate material. Can be made.
[0064]
When the bending motion piezoelectric actuator 82 is in a flat state, the fluid flowing on the surface of the structure 81 travels straight in the straight arrow 83, but each bending motion piezoelectric element as shown in FIGS. When the actuator 82 bends in a wave shape, the resistance to the fluid on the structure 81 side increases, and the flow can be changed in a wave shape as indicated by a wavy arrow 84.
[0065]
Although the above is a case where a plurality of bending operation piezoelectric actuators are used, the same operation can be performed by one bending operation piezoelectric actuator. This principle can also be used in devices that control the flow rate and flow rate of fluids such as air and water, and that give buoyancy to the structure.
[0066]
Example 7
FIG. 14 is a diagram illustrating a usage example (Example 7) of the piezoelectric actuator according to the present embodiment. In FIG. 14, piezoelectric actuators in which electrodes are concentrically arranged are configured in an array, and the heights of the protrusions of each piezoelectric actuator are adjusted, so that a dot diagram display device or a macro-texture (smooth or rough feeling) is obtained. ) A surface irregularity variable device applicable to the variable device is shown. (A) is a perspective view which shows a structure, (b) is a side view which shows a structure, (c) is operation | movement explanatory drawing.
[0067]
14 (a) and 14 (b), a plurality of piezoelectric actuators (3 × 3 in the illustrated example) 92 arranged in an array on a base 91 have a large number of concentric electrodes on the front and back surfaces of a disk-shaped piezoelectric plate material. Has been placed. For safety, an insulating film 93 is coated on the upper surface touched by a hand so as to allow a protrusion to be recognized from above the base 91 and the piezoelectric actuator 92.
[0068]
When a voltage is selectively applied to this electrode group to generate a strain similar to that generated by a rectangular plate-shaped piezoelectric actuator, the central portion of the disk-shaped piezoelectric actuator 92 can be pushed up or recessed, As shown in FIG. 14 (c), a minute protrusion 94 can be generated compared to the stationary state.
[0069]
By arranging the disk-like piezoelectric actuators 92 in an array at a minute interval, the apparent surface property of the surface of the base 91 can be varied, and the friction coefficient changes macroscopically. As a result, the spatial frequency of the protrusions can be changed to change the expression of the surface sensation such as a smooth feeling or a rough feeling felt when rubbing with a hand.
[0070]
In this way, by artificially changing the surface properties such as unevenness and roughness of the material surface, it can be applied as a tactile display of a type mainly changing the texture (a friction coefficient variable device in a minute region).
[0071]
As described above, according to the present embodiment, the piezoelectric constant of the piezoelectric plate material, the mechanical structure of the piezoelectric plate material, the shape of the electrode, the size of the electrode, the position of the electrode, the electrode selection pattern at the time of polarization, By changing the voltage, the electrode selection pattern during use, and the voltage during use, the electric field strength distribution during operation can be changed, and the distortion can be controlled by the uneven distribution of the electric field strength distribution. The piezoelectric actuator having the structure can realize the expansion / contraction operation and the bending / swinging operation with high accuracy, and can provide a piezoelectric actuator that can be used for various applications.
[0072]
【The invention's effect】
As described above, according to the present invention, the amount of expansion / contraction displacement in one fine region can be determined by performing binary control that applies a voltage that allows stable operation in a fine region by the multi-electrode method, so that it is easier. Therefore, it is possible to provide a monolithic piezoelectric actuator that can control the amount of expansion and contraction and can perform bending and twisting operations with high accuracy.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a piezoelectric actuator according to an embodiment of the present invention.
FIG. 2 is a side view showing a specific example of dimensions of a piezoelectric actuator manufactured for checking operation.
FIG. 3 is a perspective view showing a specific appearance and size example of the piezoelectric actuator manufactured as described above.
FIG. 4 is an explanatory diagram of formation of an electric field strength distribution inside a piezoelectric plate material.
FIG. 5 is an explanatory diagram of displacement measurement.
FIG. 6 is an explanatory diagram of an attitude control operation.
FIG. 7 is an explanatory diagram of a rotating operation. (A) is a non-operation state diagram, (b) is an operation state diagram.
FIG. 8 is a diagram showing a use example (Example 1) of the piezoelectric actuator according to the present embodiment.
FIG. 9 is a diagram showing a usage example (Example 2) of the piezoelectric actuator according to the present embodiment; (A) is the figure which shows the principal part of VTR with a dynamic tracking function, (b) is explanatory drawing of track deviation, (c) is explanatory drawing of the space generation by tracking, (d) is the piezoelectric actuator by this Embodiment. It is explanatory drawing of the tracking operation | movement when used, and the operation | movement prevention of space generation | occurrence | production.
FIG. 10 is a diagram showing a usage example (Example 3) of the piezoelectric actuator according to the present embodiment. (A) is a block diagram of the conventional AFM sensing part, (b) is a block diagram of the cantilever and manipulator by this Embodiment.
FIG. 11 is a diagram showing a usage example (Example 4) of the piezoelectric actuator according to the present embodiment; (A) is a block diagram and (b) and (c) are operation explanatory diagrams.
FIG. 12 is a diagram showing a usage example (Example 5) of the piezoelectric actuator according to the present embodiment; (A) is a block diagram, (b) is operation | movement explanatory drawing.
FIG. 13 is a diagram showing a usage example (Example 6) of the piezoelectric actuator according to the present embodiment. (A) is a perspective view which shows a structure, (b) is side sectional drawing which shows a structure, (c) (d) is operation | movement explanatory drawing.
FIG. 14 is a diagram showing a usage example (Example 7) of the piezoelectric actuator according to the present embodiment; (A) is a perspective view which shows a structure, (b) is a side view which shows a structure, (c) is operation | movement explanatory drawing.
[Explanation of symbols]
1 Piezoelectric plate material
1a Fixed part during measurement
1b Electrode formation region
2, 3 electrode group
2a-2i, 3a-3i electrode
4a-4i, 5a-5i switch
6 DC power supply
7 Polarization electric field (initial polarization electric field)
10 Clamp
20 Attitude control spacing control actuator
21 Prop
22 discs
23 Slider
24 disc rotation motor
25, 26 space
30 VTR drum
31 Magnetic tape
32 Magnetic head
33 Tracking actuator
35 Normal recording / playback track without bending
36 Bending track causing tracking error
37 space
41 Manipulator
42 Cantilever
43 Sensor (Tip)
44 X-axis operation direction
45 Y-axis operation direction
46 Z-axis operation direction
47 Observation target
51 Cantilever
52 Electrode group
53 Fixed part
54 X-axis operation direction
55 Y-axis operation direction
56 Z-axis operation direction
61 Piezoelectric plate material
62 electrodes
63 Wiring
64 switch electrodes
65a to 65f Relay contacts that constitute a relay switch
66 Signal line to be switched
71 case
72 Bending motion piezoelectric actuator
73 Fluid inlet
74 Fluid outlet
75 fluid
81 Arbitrary structures
82 Bending motion piezoelectric actuator
83 Fluid flow before change
84 Modified fluid flow
91 base
92 Disc-shaped piezoelectric actuator
93 Surface coating
94 Microprotrusions

Claims (4)

A number of electrodes having a shape, size, and relative position for performing a desired operation , arranged in a state of being insulated from each other on each of the opposing front and back surfaces of the monolithic plate-like piezoelectric material ,
And a switch circuit that can connect the plurality of electrodes to the DC power source independently,
The switch circuit is connected to the positive electrode and the negative electrode of the DC power supply, or the control to connect to the positive electrode or the negative electrode of the DC power supply, or the control that does not connect to any of the electrodes. The direction and magnitude of the electric field during polarization generated between the electrode and the electrode in contact with each other can be changed to create an arbitrary polarization state, and at the time of driving generated between the electrode that is a positive electrode and the electrode that is a negative electrode Making the direction and magnitude of the electric field variable, and performing all or part of the expansion / contraction operation, bending operation, and rotation operation in the arrangement region of the multiple electrodes;
A piezoelectric actuator characterized by The piezoelectric actuator according to claim 1,
The plate-like piezoelectric material is formed in a rectangular shape, and the plurality of electrodes are arranged in an array on almost the entire front surface or back surface or a specific region,
A piezoelectric actuator characterized by The piezoelectric actuator according to claim 2,
The rectangular plate-shaped piezoelectric material has one end side as a fixed portion, and the plurality of electrodes are arranged in an array on the front and back surfaces on the other end side,
A piezoelectric actuator characterized by The piezoelectric actuator according to claim 1,
The plate-like piezoelectric material is formed in a disk shape, and the multiple electrodes are concentrically arranged on the front and back surfaces.
A piezoelectric actuator characterized by

Images