JPS63194581A - Manufacture of piezoelectric actuator - Google Patents

Abstract

PURPOSE:To form the area of expansion and contraction oscillation correctly, by a method wherein the piezoelectric sheet is polarized in each neighboring first electrode area located before (after) bonding the piezoelectric sheet and a conductive elastic body, thereafter, the piezoelectric sheet is separated between electrodes. CONSTITUTION:A cushion sheet 29 is laid on a stator stand 37, supporting a rotary shaft 35 rotatably, then, a piezoelectric actuator, made by bonding a piezoelectric oscillating piece 25 and a conductive elastic sheet 20, is attached onto the sheet 29 to form a stator while an annular slider 41 is superposed and the slider is fixed to the rotary shaft 35 to form a rotor, whereby a piezoelectric motor is constituted. In the piezoelectric actuator, split electrodes 13, 17 are arranged on the conductive elastic sheet 29 with predetermined correct positional relation by a method wherein the elastic sheet 29 is bonded to the piezoelectric oscillating piece 25 and, thereafter, a piezoelectric sheet 11 is cut and separated into every individual split electrodes 13, 17. As a result, troublesome process is unnecessary and the manufacture of the piezoelectric actuator is simplified.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to the manufacturing direction of piezoelectric actuators.

For example, the present invention relates to improvements in the manufacturing direction of piezoelectric actuators suitable for piezoelectric motors.

[Conventional technology]

In recent years, piezoelectric motors using piezoelectric actuators have been proposed;
As shown in the figure, a plurality of divided electrodes 3 are formed on one side of a flat piezoelectric plate 1, a common electrode 5 is formed on the opposite surface of the piezoelectric plate 10 so as to overlap with the divided electrodes 3, and It has a structure in which the piezoelectric plate I is alternately polarized in the opposite thickness direction for each region, and the metal conductive elastic plate 7 is fixed to the piezoelectric plate I with adhesive so as to be in contact with the divided electrodes 3. Ta.

In such a piezoelectric actuator, when a predetermined alternating current voltage is applied between the common electrode 5 and the conductive elastic plate 7, that is, between the common electrode 5 and the divided electrode 3, the piezoelectric plate 1 is connected to the adjacent divided electrode 3.
The conductive elastic plate 7 fixed to the piezoelectric plate I bends and vibrates by repeating the stretching vibration (arrows in Fig. 11) alternately every time.
As shown in Fig. 2, a traveling wave A, which is a combination of longitudinal waves and transverse waves, is formed on the surface of the conductive elastic plate 7, and the wave A increases over an hour.
.

Proceed as follows. In FIG. 12, the symbol ω is the horizontal width of the traveling wave, and the symbol U is the vertical amplitude, and the traveling wave is a composite of these.

Therefore, if the slider 9 is placed on the conductive elastic plate 7, the traveling wave A can move the slider in the direction opposite to the traveling direction of the traveling wave A.

In the piezoelectric actuator described above, it is necessary to polarize each divided electrode 3 in the opposite thickness direction.

Since good traveling waves cannot be generated unless the divided electrodes 3 are arranged in an accurate positional relationship, conventionally the divided electrodes 3 and the common electrode 5 are formed on one piezoelectric plate 1, and the divided electrodes 3 are used to intersect. The conductive elastic plate 7 was manufactured by applying opposite polarization to the conductive elastic plate 7.

[Problem that the invention seeks to solve]

However, since the piezoelectric actuator manufactured by such a manufacturing method alternately causes stretching vibrations in one piezoelectric plate 1, the magnitude of the stretching vibrations is limited, and the conductive elastic plate 7 is subjected to bending vibrations with a large displacement. It was difficult to do so.

In order to cause the conductive elastic plate 7 to bend and vibrate with a large displacement, it is sufficient to apply a high drive voltage between the 9-divided electrode 3 and the common electrode 5, but applying too high a drive voltage will cause unreasonably large stretching and contraction vibrations. If this happens, there is a risk that the piezoelectric plate 1 will crack, and the quality of the piezoelectric plate 1 will deteriorate.

Furthermore, there is an idea to form a plurality of piezoelectric plates for each two-part electrode 3 and attach them to the conductive elastic plate 7, but in order to generate traveling waves, it is necessary to form the expansion/contraction vibration area of the piezoelectric plate in an accurate positional relationship. However, it is extremely troublesome and difficult to accurately attach each piezoelectric plate to the conductive elastic plate 7 in a predetermined positional relationship.
It has the disadvantage of causing a sharp increase in costs.

The present invention was made to solve these conventional drawbacks, and provides a highly reliable piezoelectric actuator that is easy to manufacture and can generate large stretching vibrations without causing cracks in the piezoelectric plate. It provides a manufacturing method that can be used.

[Means for solving problems]

The present invention aims to solve these problems.

As shown in FIGS. 1 and 2, a piezoelectric plate 11 is prepared, and a plurality of first electrodes 13, 17 are arranged and formed on one side of the piezoelectric plate 11 at intervals. a second electrode 21 opposite the first electrode 13.17 on the surface;
．． form 23.

On the other hand, a conductive elastic body 29 made of metal or the like is prepared (FIG. 4), and is bonded to the piezoelectric plate 11 on the first electrode 13.17 side or the second electrode 21.23 side (Fig. 4). 5
figure). Before or after the conductive elastic body 29 is attached to the piezoelectric plate 11.

Polarization treatment is performed alternately in opposite directions for each of the adjacent first electrode 13 and 17 regions (FIG. 3).

After the polarization process and bonding process, the sixth
As shown in the figure, the piezoelectric plate 11 is separated between adjacent first electrodes 13 and 17 to produce a piezoelectric actuator.

[For production]

The invention provided with such means generally comprises the first and second electrodes 13.1? , 21, 23 are easily formed with extremely accurate positional relationships, and the piezoelectric plate 1 with these electrodes formed thereon.
1 to the conductive elastic plate 29, the elastic vibration regions of the piezoelectric plate 11 are arranged in an accurate positional relationship, and reverse polarization processing can be easily performed for each elastic vibration region.

On the other hand, the piezoelectric plate 11 bonded to the conductive elastic material 29 is
Even if the electrodes 13 and 17 are separated, the positional relationship of each elastic vibration area is maintained accurately, and each elastic vibration area is not continuous but becomes almost independent, allowing each elastic vibration to vibrate freely. Therefore, large stretching vibrations are likely to occur, and even if large stretching vibrations occur, the piezoelectric plate 11 is difficult to crack, and in order to generate stretching vibrations of the same magnitude, it is only necessary to apply a smaller drive voltage than in the past.

〔Example〕

The present invention will be explained in detail below.

1 to 6 are process diagrams showing one embodiment of the present invention.

First, a ferroelectric material such as barium titanate (BaTi03) or lead zirconate titanate (PbZr03-PbTiO3) is formed into a flat ring shape and fired to make a piezoelectric plate 11 as shown in FIG. (hidden in Figure 1) and the lower surface opposite to this are polished.

Next, as shown in FIG. 2A, a first section electrode 15 consisting of eight divided electrodes 13 arranged in the circumferential direction at predetermined intervals is placed on the top surface of the piezoelectric plate 11; Split electrode 1
7 are formed asymmetrically with an interval of (3/4) λ. The symbol λ is the natural vibration wavelength of the piezoelectric actuator.

On the lower surface of the piezoelectric plate 11, as shown in FIG. 2B.

The two common electrodes 21, 23 are formed asymmetrically.

One common electrode 21 faces the first section electrode 15 , and the other common electrode 23 faces the second section electrode 19 .

These divided electrodes 13.17 and common electrodes 21.23 are formed by a conventionally known method, such as by vapor depositing or printing a conductive metal material such as silver on the upper and lower surfaces of the piezoelectric plate 11.

Next, the piezoelectric plate 11 is provided with a single divided electrode 13 and a divided electrode 1.
7, as shown in FIG.

The piezoelectric vibrator 25 is formed by alternately applying opposite polarization in the thickness direction.

To alternately apply opposite polarization, a high DC voltage is applied between every other divided electrode 13.17 of the 1 divided electrodes 13, 17 and the common electrode 21.23, while the remaining 9 divided electrodes 13.17 are A high DC voltage of opposite polarity may be applied between every other electrode and the common electrode 21, 23.

Next, a conductive elastic plate 29 is prepared by molding, for example, a copper alloy into a ring shape, and having a large number of diametrical slits 27 formed in the shape of a comb at narrow intervals in the upper part (FIG. 4).

Then, the piezoelectric vibrator 25 and the conductive elastic plate 29 are bonded together using an epoxy adhesive so that the one-segment electrode 13.17 and the conductive elastic plate 29 are in contact with each other, thereby producing a piezoelectric actuator as shown in FIG.

Furthermore, as shown in FIG.
The piezoelectric plate 11 is cut from the common electrode 21.23 side using a cutter (not shown) to separate the piezoelectric plate 11 into each divided electrode 15.17. As a guide when cutting, common electrode 2
1.23, it is preferable to form a mark at a position corresponding to the electrode gap region 31.

Reference numeral 33 in FIG. 6 is a separation groove. Furthermore, although an extremely shallow separation groove may be formed in the conductive elastic plate 29 during cutting, this does not impede the operation of the piezoelectric actuator.

The piezoelectric actuator manufactured in this way has nine divided electrodes 1
3.17 are in common contact with the conductive elastic plate 29,
As shown in FIG. 7, the common electrode 21 and the conductive elastic plate 29
An alternating current voltage A (V (Isinωt)) with a frequency equal to the natural frequency of the piezoelectric actuator is applied between the common electrodes 23 and 23.
An alternating current voltage B that is equal to the natural frequency of the piezoelectric actuator and whose temporal phase differs by 90° is applied between the conductive elastic plate 29 and the conductive elastic plate 29.
By applying (VOcosωt), the piezoelectric plate 11
The divided electrodes 13 and 17 alternately expand and contract in the circumferential direction. Note that since the common electrodes 21 and 23 are each divided, they are commonly connected by conductive wires.

Therefore, the conductive elastic plate 29 attached to the piezoelectric vibrator 25
Two different standing waves are generated, and these two standing waves interfere to generate a traveling wave that travels in the circumferential direction (see FIG. 12). Therefore, if a load is placed on the conductive elastic plate 29,
This traveling wave moves the load.

In this way, in the present invention, after the piezoelectric vibrator 25 and the conductive elastic plate 29 are pasted together, the piezoelectric plate 11 is attached to the individual divided electrodes 1.
3. Just cut and separate every 17 seconds.

Since the divided electrodes 13, 17 are arranged on the conductive elastic plate 29 in a predetermined and accurate positional relationship, there is no need for the troublesome process of attaching a piezoelectric plate formed for each divided electrode, thereby simplifying manufacturing. A good traveling wave can be obtained by vibrating regions with accurate positional relationships.

Moreover, between the five adjacent divided electrodes 13 and 17, the piezoelectric plate 11 is divided into individual divided electrodes 13 and 17 by the separation groove 33, so that the piezoelectric plate 11 sandwiched between the two divided electrodes 13 and the common electrode 21, In the portion of the piezoelectric plate 11 sandwiched between the divided electrode 17 and the common electrode 23, each vibration area is independent, and sufficient stretching vibration is possible without being affected by neighboring stretching vibrations. Bending vibration occurs and a traveling wave with a large amplitude is obtained.

In addition, even if a large driving voltage is applied between the common electrode 21.23 and the divided electrode 13.17 and a large expansion/contraction vibration occurs, the piezoelectric plate 11 will not easily break, and even if the same level of driving voltage is applied as before, the piezoelectric plate 11 will not break easily. In the example, since it is possible to obtain an expansion and contraction vibration larger than the magnitude that occurs in the piezoelectric plate 11, in order to obtain a traveling wave of the same degree as the conventional one, it is sufficient to apply a smaller drive voltage, and the drive circuit that outputs the drive voltage It becomes possible to reduce the scale of the drive circuit, thereby reducing the power consumption of the drive circuit and improving reliability.

FIG. 8 is a diagram showing a piezoelectric motor using a piezoelectric actuator manufactured according to the present invention.

A cushion sheet 39 is laid on a stator base 37 that rotatably supports a rotating shaft 35, and a piezoelectric actuator in which a piezoelectric vibrator 25 and a conductive elastic plate 29 are bonded together is attached thereon to form a stator.

A piezoelectric motor is constructed by stacking a ring-shaped slider 41 on a conductive elastic plate 29 and fixing this to a rotating shaft 35 to form a rotor.

When a driving AC voltage is applied to the piezoelectric vibrator 25, a traveling wave is generated on the upper surface of the conductive elastic plate 29, the slider 41 rotates, and rotational force is obtained from the one-rotation shaft 35. Note that reference numeral 43 is a spring that adjusts the pressing force of the slider 41 to the conductive elastic plate 29.

The embodiment shown in FIG. 1 described above has a configuration in which a flat ring-shaped piezoelectric vibrator 25 and a ring-shaped conductive elastic plate 29 are laminated in the vertical direction. It can also be carried out when manufacturing a piezoelectric actuator in which a piezoelectric vibrator is formed by forming electrodes on the inner and outer surfaces facing each other, and a ring-shaped conductive elastic plate is attached to the inside or outside of the piezoelectric vibrator. It is.

Another aspect of the present invention is that, as shown in FIG. 9, split electrodes (limited to the middle of FIG. 9) are arranged linearly at predetermined intervals on one side of a rectangular piezoelectric plate 45.

A manufacturing method is also possible in which the common electrode 47 is formed on the back surface and the piezoelectric plate 45 is cut and separated from the common electrode 47 side in each inter-electrode gap region. Reference numeral 49 is a separation groove, and reference numeral 5 is a separation groove.
1 is a conductive elastic plate that is bonded to the piezoelectric plate 45.

In the piezoelectric actuator having such a configuration, a linear traveling wave is generated in the conductive elastic plate 51, so that it is possible to move the load in a linear direction.

In this way, the direction in which the piezoelectric plate 111.45 is cut and separated can be selected depending on the arrangement and layout of the divided electrodes 13.17.
Any direction may be used as long as it crosses the arrangement direction of the divided electrodes 13, 17, and the separation method is not limited to cutting.

Further, in the present invention, as shown in FIG. 10, a divided electrode 55 is formed on one side of a piezoelectric plate 53 and a common electrode 57 is formed on the opposite side, and the common electrode 57 is brought into contact with a conductive elastic plate 59. It is also possible to form the separation groove 61 by laminating the piezoelectric plate 53 and the conductive elastic plate 59 and cutting and separating the piezoelectric plate 53 from the two-part electrode 55 side.

In this method of separating the piezoelectric plate 53 from the two-divided electrode 55 side, it is not necessary to form marks for the three separation positions on the common electrode 57 in advance, and polarization can be performed after the piezoelectric plate 53 is attached to the conductive elastic plate 59. It is.

In the present invention, the shapes of the piezoelectric plates 11, 45, 53 and the conductive elastic plates 29, 51, 59 can be deformed depending on the device that uses the piezoelectric actuator as a drive source, and the positions separated by one can be arbitrary. divided electrode 13, 17.55
There is no need to form it in the gap region between.

〔Effect of the invention〕

As explained above, the piezoelectric actuator manufacturing method of the present invention involves polarizing the piezoelectric plate alternately in opposite directions for each adjacent first electrode region before or after pasting the piezoelectric plate and the conductive elastic body. Then, the piezoelectric plate is separated between the adjacent first electrodes, so that the piezoelectric plate formed for each 9-divided electrode is formed on the conductive elastic plate so that the expansion and contraction vibration regions of the piezoelectric plate are accurately positioned. At the same time, the expansion and contraction vibration regions can be arranged in an independent positional relationship very easily.

Therefore, manufacturing is simple and costs can be suppressed, a traveling wave with a large amplitude can be obtained, and reliability is improved without degrading quality.

9 Application examples of the piezoelectric actuator of the present invention include:
In addition to the piezoelectric motor described above, various other applications are possible.

[Brief explanation of the drawing]

1 to 6 are process diagrams showing an embodiment of the piezoelectric actuator manufacturing method according to the present invention, and FIG.
FIG. 8 is a perspective view (partially cut away) showing an electronic device using a piezoelectric actuator manufactured according to the present invention using a piezoelectric motor as an example; 9 and 10 are perspective views and sectional views of essential parts showing other examples of the piezoelectric actuator manufacturing method of the present invention, FIG. 11 is a partial sectional view showing a conventional piezoelectric actuator, and FIG. 12 is a piezoelectric actuator. FIG. 1.11, 45.53... Piezoelectric plate 3.13, 17.55... First electrode (divided electrode) 5.21.23, 47.57, Second electrode (common electrode) 7.29, 51.59... conductive elastic plate treated with conductive elastic)

Claims (1)

[Scope of Claims] A plurality of first electrodes are arranged and formed at intervals on one side of a piezoelectric plate, and a second electrode facing the first electrode is formed on the opposite side of the piezoelectric plate. a step of alternately subjecting the piezoelectric plates in the adjacent first electrode regions to polarization treatment in opposite directions; and a step of laminating the piezoelectric plates and a conductive elastic body on the first or second electrode side. A method for manufacturing a piezoelectric actuator, comprising the steps of: separating the piezoelectric plate between the adjacent first electrodes after the polarization treatment step and the bonding step are completed.