JPH02261071A - piezoelectric actuator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to increasing the tensile force of a piezoelectric plate (or electrostrictive plate) by changing the voltage between electrodes arranged to sandwich the piezoelectric plate (or electrostrictive plate). This invention relates to a piezoelectric actuator that acts on the outside.

[Conventional technology]

In recent years, a scanning tunneling microscope (STM) has attracted attention as a device that can observe the morphology of a solid surface in real space with atomic-scale resolution. This scanning tunneling microscope
When a metal needle is brought close to a solid surface to a distance of 10 m or less and a voltage of several volts or less is applied between the needle and the solid surface, a tunnel current of several nA flows through the vacuum barrier between them. This tunnel current is proportional to the valence band of the sample or to the density of states of empty levels in the conduction band of the sample, depending on the voltage polarity. Therefore, let the tunnel voltage be ■, the tunnel current be
When measured as the r rr number, information on the density of states of the band structure of the sample can be obtained.

The basics of this device include a coarse movement mechanism that allows the sample to be moved over a wide range relative to the needle, and a fine movement mechanism that allows the needle to scan in three dimensions. Among these, the coarse movement mechanism is a mechanism that allows a piezoelectric plate material such as PZT (lead zirconate titanate) or PLZT (lead lanthanate zirconate titanate) to expand and contract in the XYZ directions and walk in two dimensions, while the fine movement mechanism is a mechanism that allows it to walk in two dimensions. A mechanism called a "tri-bod" is used in which piezoelectric plates are arranged orthogonally in the X, Y, and Z directions.

Here, the piezoelectric plate material has the property of inducing a voltage when a force is applied to it, and conversely generating a force when a voltage is applied to it. Therefore,
As shown in FIG. 12, plate-shaped or membrane-shaped electrodes 2 are arranged to sandwich a disc-shaped piezoelectric plate 1, and a battery 3 and a switch 4 are connected in series between these electrodes. When this switch 4 is opened and closed, the piezoelectric plate 4 (1) changes as shown in FIG. The plate material 1 maintains its disk shape when molded as shown in Figure (a), but when the switch 4 is closed, the electric field between the electrodes causes the piezoelectric plate material 1 to change the electric field as shown in Figure (b). expand in the direction.

In this case, since the elongation in the direction of the electric field is small, it is necessary to laminate the piezoelectric elements shown in FIG. 12 in order to secure the required amount of deformation. The above-mentioned "tri-bod" is also based on a laminated structure, but in this specification, regardless of the number of layers, the tension force is applied externally by changing the voltage between the electrodes arranged to sandwich the piezoelectric plate material. The device that does this will be called a piezoelectric actuator.

[Problem to be solved by the invention]

Generally, when a voltage is applied to a disk-shaped piezoelectric plate whose electrode mounting surfaces are formed parallel to each other, the amount of strain at the center of the electrode mounting surface changes from the amount of distortion around it as shown in Figure 13(b). It is larger and the plate surface deforms into an almost spherical shape. On the other hand, in order to apply the tensile force of the piezoelectric plate 1 to the outside, it is necessary to bring the piezoelectric plate and the object to be applied into contact with each other to couple them together.

In this case, as shown in FIG. 14(a), the affected object 5
If the abutment surfaces of the piezoelectric plates 1 and 1 are connected so that they are perpendicular to the axis of the piezoelectric plate 1, a force F acts on the actuated object 5 only in the axial direction. However, if the acting surface of the actuated object 5 is connected at an angle with respect to the axis of the piezoelectric plate 1, as shown in FIG. 13(b), the axial force F and the A force F that is decomposable acts on the force F .

In this way, if the surface to be acted upon of the object to be acted upon is even slightly inclined with respect to the axis, this will impede the transmission of force, and especially in the above-mentioned "tri-bod", it is difficult to move the needle in a different direction than expected. It could also be the reason for the move.

The present invention was made in order to solve the above-mentioned problems, and an object of the present invention is to obtain a piezoelectric actuator that can suppress the generation of unnecessary component force on an object to be acted upon.

[Means to solve the problem]

The present invention is characterized in that a plate-like body or a membrane-like body having a cross-sectional shape in which at least one intermediate portion is partially cut out is used as the electrodes arranged to sandwich the piezoelectric plate material. It is something.

As a specific example of such an electrode, a comb-like or net-like electrode can be used.

[For production]

In this invention, since an electrode is used in which at least one part of the intermediate part is partially cut out, the piezoelectric plate material deforms more in the range excluding this intermediate part, and the piezoelectric plate material deforms more in the range excluding this intermediate part, and the piezoelectric plate material deforms more in the range excluding this intermediate part, and the Therefore, the generation of unnecessary force can be suppressed compared to conventional piezoelectric actuators in which the force is concentrated at one point in the center.

In this case, if the teeth of the comb-shaped electrodes are arranged so that they overlap in parallel, a force based on line contact can be applied, whereas if the teeth of the comb-shaped electrodes are arranged so that they intersect, a force that is based on point contact can be applied. Further, by using a mesh electrode, it is possible to apply a force based on so-called matrix contact in which the line contact portions intersect.

〔Example〕

FIG. 1 is a perspective view showing the structure of an embodiment of the present invention. In the figure, the piezoelectric plate 11 is formed into a rectangular shape. The electrodes arranged on both sides of the piezoelectric plate 11 may be coated with a conductive paste, or
Although a structure in which a metal film is vapor-deposited may be used, in order to make the shape clear, electrodes 12 and 13 in the form of a comb-teeth punched metal plate are used here. In this case, the electrode 12
has a common connection part 12A and a southern part 12B, and the electrode 13 also has a common connection part 13A and a southern part 13B. These electrodes 12.13 may be attached to both sides of the piezoelectric plate 11 as shown in FIG.
Teeth 12B, 13B are located at the ends opposite to A.
are attached so that they overlap each other. Therefore, if the electrode is cut along the line X--X in FIG. 2, the cross-sectional view will be an electrode with four cutouts in the middle, as shown in FIG. Here, if the battery 3 and the switch 4 described above are connected in series between the common connection part 12A of the electrode 12 and the common connection part 13B of the electrode 13 and the switch 4 is closed, the result will be as shown in FIG. Then, the piezoelectric plate 11 deforms so that the portions sandwiched between the teeth 12B and the peaks 13B bulge linearly.

Therefore, according to this embodiment, force can be applied to the object at a plurality of linearly bulging locations.

FIG. 5 is a perspective view showing the structure of another embodiment of the invention. Although this uses a piezoelectric plate 11 and electrodes 12 and 13 having substantially the same shapes as those of the above embodiment, the mounting state thereof is different. That is, the common connection portion 12A of the electrode 12
and the common connection part 13A of the electrode 13 are located at ends in directions 90 degrees different from each other, and the tooth part 12B of the electrode 12
and the teeth 13B of the electrode 13 are mounted so that they are orthogonal to each other. FIG. 6 shows this installed state. here,
If the battery 3 and the switch 4 described above are connected in series between the common connection part 1.2A of the electrode 12 and the common connection part 13A of the electrode 13 and the switch 4 is closed, as shown in FIG. , the portions 11H where the tooth portions 12B and 13B overlap each other are deformed so as to swell locally. Therefore,
According to this embodiment, a stretching force can be applied to the object at a plurality of locally swollen locations.

Next, FIG. 8 is a perspective view showing the structure of another embodiment of the present invention. This uses a plurality of windows 14A, 15A formed in rows in the vertical and horizontal directions, respectively, and electrodes 14, 15 having external connections 14B, 15B at appropriate corners. These electrodes 14, 15 are attached to both sides of the piezoelectric plate 11 as shown in FIG.
A and the window 15A are mounted so that they overlap each other, that is, the matrix-shaped portions other than the windows overlap. Therefore, if the cross-sectional view is taken along the line X--X in FIG. 9, the cross-sectional view will be as shown in FIG. 10. Here, the external connection part 1 of the electrode 14
4B and the external connection part 15B of the electrode 15, if the battery 3 and the switch 4 described above are connected in series and the switch 4 is closed, the window 14A and the window 15 are closed, as shown in FIG.
The part 11L that overlaps with A remains as it is, and this part 11L
The portion other than , that is, the matrix-like portion where a plurality of straight lines are perpendicular to each other can apply a stretching force to the object.

Although the preferred embodiments have been described above, the present invention is not limited thereto, and may have a structure in which a conductive paste is applied instead of the plate electrode, or a conductive film is vapor-deposited. In short, by using a plate-like body or a membrane-like body having a cross-sectional shape in which at least one part of the intermediate part is partially cut out, a stretching force can be applied to the object at multiple places as described above. can be done.

In the above embodiment, a square piezoelectric plate is used, but it is clear that the present invention can also be applied to a circular piezoelectric plate, an elliptical or a polygonal plate instead.

Furthermore, in the above embodiment, a scanning tunneling microscope (ST
Although the piezoelectric actuator applied to M) has been described, it goes without saying that the present invention can also be applied to other devices, such as a device for moving a laser beam during IC manufacturing.

〔Effect of the invention〕

As is clear from the above explanation, according to this invention,
Since the piezoelectric plate is stretched at multiple locations using an electrode with at least one part of the middle part partially cut out,
Force is applied to the object at multiple locations, thereby suppressing the generation of unnecessary component forces.

[Brief explanation of drawings]

Fig. 1 is an exploded perspective view showing a schematic configuration of an embodiment of the present invention, Fig. 2 is a perspective view showing the installed state of elements constituting the embodiment, and Fig. 3 is a sectional view of essential parts of the embodiment. , FIG. 4 is a perspective view showing a main part in cross section to explain the operation of the same embodiment, FIG. 5 is an exploded perspective view showing the schematic structure of another embodiment of the invention, and FIG. 6 is the same. FIG. 7 is a perspective view of the main elements for explaining the operation of the embodiment; FIG. 8 is a schematic diagram of another embodiment of the present invention; FIG. Fig. 9 is an exploded perspective view showing the configuration, Fig. 9 is a perspective view showing the installed state of the elements constituting the embodiment, Fig. 10 is a sectional view of the main part of the embodiment, and Fig. 11 explains the operation of the embodiment. 12 is a schematic configuration diagram of a conventional piezoelectric actuator, FIGS. 13(a) and 13(b) are sectional views showing the deformed state of this piezoelectric actuator, and FIG. 14 is a perspective view of the main elements for
Figures (a) and (b) are cross-sectional views for explaining the operating state of the stretching force of this piezoelectric actuator. 1.11... Piezoelectric plate, 2.12-15... Electrode, 3... Battery, 4... Switch, 1.2A, 13A
...Common connection part, 12B, 13B...Tooth part, 14A
, 15A...window.

Claims (3)

[Claims] 1. In a piezoelectric actuator that applies a stretching force of the piezoelectric plate to the outside by changing the voltage between electrodes arranged to sandwich a piezoelectric plate, at least one part of the intermediate portion is partially cut out as the electrode. A piezoelectric actuator characterized by using a plate-like body or a film-like body having a cross-sectional shape. 2. The piezoelectric actuator according to claim 1, wherein the electrode is formed in a comb-teeth shape. 3. 2. The piezoelectric actuator according to claim 1, wherein the electrode is formed in a net shape.