JP3150737B2 - Manufacturing method of piezoelectric diaphragm for ultrasonic motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for manufacturing a piezoelectric diaphragm for an ultrasonic motor.

[0002]

2. Description of the Related Art As an ultrasonic motor, for example, a configuration as shown in FIG. 6 is known. That is, an annular concave portion 5 surrounding the bearing 1 is formed in a base 3 in which the radial type bearing 1 is fitted in a central through hole, and a convex ring portion 7 integrally projecting on one end surface side (upper side in FIG. 6). A metal disk-shaped elastic body 9 is fixed to the base 3, and a radial cut (not shown) is formed in the convex ring 7 of the elastic body 9 to form a large number of convex ring 7 in the circumferential direction. The elastic body 9 is divided, and a ring-shaped piezoelectric vibrating plate 11 is affixed to the other end surface (lower side in FIG. 6) of the elastic body 9 at a position overlapping with the convex ring portion 7.

As shown in FIG. 7, a piezoelectric vibrating plate 11 is composed of a piezoelectric vibrating plate element 13 made of a piezoelectric ceramic plate and a first polarizing region 15 having an arc shape in which a polarization direction is alternately changed and polarization is applied in a thickness direction. And a second polarization region 17 having an arc shape deviated by λ / 4 from the first polarization region 15 by performing polarization in the thickness direction by alternately changing the polarization direction. Arc-shaped common drive electrodes 19 and 21 are formed in the first and second polarization regions 15 and 17, and a sensor electrode 23 is provided between the common drive electrodes 19 and 21. The polarization in the thickness direction of the piezoelectric vibrating plate element 13 is also applied to the sensor electrode 23 portion, but the polarization is applied between the first and second polarization regions 15 and 17 at diagonal positions with respect to the sensor electrode 23. Absent.

[0004] The common drive electrode 19 of the piezoelectric vibrating plate element 13,
The flexible printed circuit board 25 or the lead wire (not shown) in FIG. 6 is connected to the sensor electrode 21 and the sensor electrode 23 and is led out. On the other surface of the piezoelectric vibrating plate element 13, individual electrodes 27 are formed independently for each polarization region as shown in FIG. 8, and these individual electrodes 27 are common via the elastic body 9 of FIG. To the flexible printed circuit board 25.

A base 3 shown in FIG. 6 is covered with a cup-shaped metal case 29, and a bearing 31 is provided in a central protruding portion of the case 29.
And a thrust type bearing 33 are fixed, and the shaft 35 is supported by the bearing 1, the bearing 31 and the bearing 33. In the case 29, a disk-shaped rotating body 37 as a moving body is fixed to the shaft 35, and a disc spring 41 is fixed by a flange 39 attached to the shaft 35.
Are pressed against the peripheral portion of the rotating body 37 against the convex ring 7 of the elastic body 9 to constitute an ultrasonic motor.

[0006] Such an ultrasonic motor has two kinds of AC drive voltages [V = V0 sinωt] and [V '= V0 si] which are 90 ° out of phase with each other and slightly higher than, for example, 40 KHz.
n (ωt ± π / 2)] from the drive circuit (not shown) to the common drive electrodes 19 and 21, the piezoelectric vibrating plate 11 bends and vibrates. The traveling ultrasonic wave is generated, the rotating body 37 rotates in the circumferential direction, and the shaft 35 rotates. In order to generate bending vibration on the piezoelectric diaphragm for an ultrasonic motor as described above, FIG.
As shown in FIG. 8, first and second polarization regions 15, 1 in which the polarization in the thickness direction is alternately changed in the piezoelectric vibrating plate element 13.
7 must be formed.

Conventionally, as a method of alternately applying different polarizations to the piezoelectric vibrating plate element 13, a common drive electrode 19, 21, a sensor electrode 23 and an individual electrode 27 formed on the piezoelectric vibrating plate element 13 are used as polarizing electrodes. The techniques used are widely known. That is, as shown in FIG. 9, the common drive electrode 19 (21) is set to zero potential and every other individual electrode 2
After applying a positive (+) high voltage to 7 to apply thickness polarization, the common drive electrode 19 (21) is kept at zero potential as shown in FIG. A high voltage of-) was applied to perform reverse thickness polarization.

[0008]

However, in the above-described method for manufacturing a piezoelectric vibrating plate, the piezoelectric vibrating plate element 13 has the common drive electrodes 19 and 21 on one side, and the plus (+) ), A negative (−) high voltage is applied to every other individual electrode 27, so that the polarization of the polarized portion to which the positive (+) high voltage is applied first returns to some extent. Polarization degradation, which is called polarization return, is likely to occur. Therefore, FIG.
As shown in FIG. 1, it is necessary to apply a plus (+) voltage again for a short time to every other individual electrode 27 to which a plus (+) high voltage is applied in the polarization step of FIG. However, since the number of polarization steps is three, the number of steps is not reduced, which is an obstacle to simplifying the manufacturing.

Moreover, even if the polarization deterioration is restored by applying the plus (+) voltage again after the application of the plus and minus high voltages, the dispersion of the degree of polarization in each polarization region may not be completely eliminated. There is a concern that the smooth rotation of the ultrasonic motor may be hindered. Further, when the piezoelectric vibrating plate 11 manufactured by the above-described manufacturing method is incorporated in an ultrasonic motor, if a crack occurs in the piezoelectric vibrating plate element 13 for some reason, a crack also occurs in the common drive electrodes 19 and 21. However, if a crack occurs in the middle of the common drive electrodes 19 and 21, a discharge also occurs at the crack portion, and there is also a fear that smooth rotation is hindered. The present invention has been made to solve such a conventional disadvantage, and it is easy to simplify the polarization process and stabilize the polarization, and cracks are generated in the piezoelectric diaphragm incorporated in the ultrasonic motor. It is still another object of the present invention to provide a method of manufacturing a piezoelectric vibrating plate that promotes cracks in electrodes and does not cause discharge at the electrode portions.

[0010]

SUMMARY OF THE INVENTION In order to solve such a problem, the present invention provides a thin plate-shaped piezoelectric vibrating plate element forming a piezoelectric vibrating plate having a plurality of first polarizing electrodes spaced apart from each other. And a plurality of second polarization electrodes are formed on the opposing surface of the piezoelectric vibrating plate element so as to overlap with the first polarization electrode at the same pitch. A polarization voltage is applied to the second polarization electrode in the thickness direction of the piezoelectric vibrating plate element while the polarization potential is alternately connected to the second polarization electrode in the reverse order of the first polarization electrode. On the other hand, polarizations having different directions are alternately applied to the electrodes, and after the polarizations, the second electrodes for polarization are electrically connected in common by a flexible connection member.

[0011]

According to the present invention having such means, the polarization potentials are alternately applied to the opposing first and second polarization electrodes formed on both surfaces of the piezoelectric vibrating plate element in the reverse order on each surface. By simply applying a voltage, the piezoelectric vibrating plate element can be alternately polarized in different directions at once. Furthermore, if these second electrodes for polarization are commonly connected by a flexible connecting member after polarization, it can be used for assembling the ultrasonic motor as it is.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. Note that the same reference numerals are given to portions common to the conventional example. 1 to 3 are process diagrams showing one embodiment of a method for manufacturing a piezoelectric diaphragm according to the present invention. First, a ring-shaped piezoelectric vibrating plate element 13 made of, for example, a piezoelectric ceramic plate is prepared, and as shown in FIG. 2, one surface thereof has a plurality of arc-shaped first polarization regions 15 in a region corresponding to an arc-shaped first polarization region 15 described later. Forming first driving individual electrodes 43 at intervals in the circumferential direction;
A plurality of second driving individual electrodes 45 are circumferentially spaced from each other in a region corresponding to an arc-shaped second polarization region 17 to be described later, which is shifted by λ / 4 from one end of the first polarization region 15. Formed. The first and second driving individual electrodes 43 and 45 are the common driving electrodes 19 and 21 of the above-described conventional example.
And functions as a second polarization electrode as described later.

A sensor electrode 23 is formed between the other end of the first polarization region 15 and the second polarization region 15.
As shown in FIG. 3, on the opposing surface of the piezoelectric diaphragm element 13,
At positions corresponding to the first and second polarization regions 15 and 17, the individual electrodes 27 having substantially the same shape as the first and second driving individual electrodes 43 and 45 and the sensor electrode 23 are formed.
The first and second drive individual electrodes 43 and 45 and the sensor electrode 23 are formed so as to face each other so as to coincide with each other. These individual electrodes 27 function as first polarization electrodes as described later.

First and second driving individual electrodes 43, 4
5. The sensor electrodes 23 and the individual electrodes 27 are formed by applying and baking a conductive paint such as a silver paste on the front and back surfaces of the piezoelectric vibrating plate element 13 with the same electrode pattern, for example. In such a piezoelectric vibrating plate 11, as shown in FIG. 1, positive and negative high voltages of the polarization power source E are alternately connected to the individual electrodes 27 on one side, and the first and second high voltages on the opposing surface side. The driving individual electrodes 43 and 45 and the sensor electrode 23 (not shown in FIG. 1) are connected alternately to the negative and positive high voltages of the polarization power supply E in the reverse order to the individual electrode 27 side. Is used as a first polarization electrode, and the first and second drive individual electrodes 43 and 45 and the sensor electrode 23 are simultaneously polarized as a second polarization electrode.

The individual electrode 27 facing the sensor electrode 23 is polarized by connecting an appropriate positive or negative high voltage (not shown in FIG. 1). Further, the polarization is performed by immersing in an insulating oil (not shown). Then, as shown in FIG. 7 or FIG. 8 described above, the arc-shaped first polarization region 15 in which the polarization in the thickness direction is continuously and alternately changed is formed on the piezoelectric vibrating plate 11.
Then, an arc-shaped second polarization region 17 is formed, which is shifted by λ / 4 from one end of the first polarization region 15 and continuously changes polarization in the thickness direction.

However, the first and second polarization regions 15 and 17 separated by λ / 4 may be polarized so as to start from minus (−) and plus (+), respectively, as shown in FIG. Although not shown, the polarization may start from plus (+) and plus (+) or minus (-) and minus (-). A ring-shaped thin flexible (flexible) substrate 47 having substantially the same shape as the piezoelectric vibrating plate element 13 separately or in parallel with the polarization processing of the piezoelectric vibrating plate 11.
Prepare On one surface of the flexible substrate 47, arc-shaped first and second connection patterns 49 and 51 overlapping the first and second driving individual electrodes 43 and 45 regions, that is, the first and second connection patterns are provided. The first and second connection patterns 49 and 51 corresponding to the polarization regions 15 and 17 of the first and second driving individual electrodes 43 and 45, respectively, and the sensor connection pattern 5 overlapping the sensor electrode 23 are formed.
Form 3

The first and second connection patterns 49,
The flexible substrate 47 having the 51 and the sensor connection pattern 53 is formed from a single-sided copper-clad flexible substrate or the like by a known method such as etching. Then, the first connection pattern 49 is applied to all of the first drive individual electrodes 43 of the first polarization region 15, and the second connection pattern 51 is applied to all of the second drive individual electrodes 45 of the second polarization region 17. And sensor connection pattern 5
The flexible substrate 47 is overlapped on the piezoelectric vibration plate 11 and fixed with a conductive adhesive or the like so that each of the first driving electrodes 3 is electrically connected to the sensor electrode 23. The connection patterns 49 are electrically connected in common, and all the second driving individual electrodes 47 are electrically connected in common in the second connection pattern 51 (see FIGS. 1 and 5).

As shown in FIG. 5, a plurality of first driving individual electrodes 43 and a plurality of second driving individual electrodes 45 are commonly connected to the piezoelectric vibrating plate 11 by the flexible substrate 47 as shown in FIG. The electrode 27 side is overlapped with the elastic body 9 and fixed in a state of being electrically connected in common, and an ultrasonic motor as shown in FIG. 6 is assembled. In the method of manufacturing the piezoelectric vibration plate according to the present invention, the individual electrodes 27 are formed on one surface of the piezoelectric vibration plate 11, and the first and second driving individual electrodes 43 and 45 similar to the individual electrodes 27 are formed. Are formed opposite to each other, alternately connecting the polarization potentials of different polarities to the individual electrodes 27 on one side, and the first and second driving individual electrodes 4 on the opposite side.
Since different polarization potentials are connected in the reverse order to the one surface side for 3 and 45, and polarization is performed at once, an extra auxiliary polarization step such as that shown in FIG. The polarization in different directions can be alternately applied to the piezoelectric vibrating plate 11 by applying the polarization voltage once.

Therefore, the polarization process is simplified, and
Since the polarization is performed without providing a common electrode common to a plurality of electrodes, the degree of polarization in each polarization region is constant, and polarization variation hardly occurs in adjacent polarization regions. In addition, stable rotational drive can be obtained. Further, even if a crack occurs in the piezoelectric vibrating plate element 13 for any reason in the ultrasonic motor, the first or second driving individual electrodes 43 and 45 near the crack are independent electrodes and the flexible substrate 47 is formed. First or second connection pattern 4
9 and 51, they are electrically connected in common.
Alternatively, the second driving individual electrodes 43 and 45 do not promote the generation of cracks, do not easily generate electric discharge, and can also ensure smooth rotation.

Moreover, in the above-described piezoelectric vibration plate 11, the first or second connection pattern 4 of the flexible substrate 47 is formed.
If the lengths of the electrodes 9 and 51 are appropriately changed, the number of the first or second driving individual electrodes 43 and 45 that are commonly connected even when the same piezoelectric diaphragm 11 is used, that is, the area of the common driving electrode is arbitrary. The piezoelectric vibrating plate 11 having various characteristics can be obtained. Incidentally, the polarization voltage is determined by the thickness of the piezoelectric vibrating plate element 13 and is not influenced by the size of the electrode area.
The drive individual electrodes 43 and 45 are formed on both sides of the piezoelectric vibrating plate element 13 and polarized as in the present invention.
Note that the polarization power supply E is provided with first and second drive individual electrodes (second polarization electrodes) 43 and 45 and individual electrodes (first electrode) directly from one power supply or two power supplies or via a resistance circuit.
Electrode 27 for polarization.

[Regarding the limitation of claims, the following five lines are deleted. The above-described manufacturing method according to the present invention is an example, and the first and second connection patterns 49, 5 are used as connection members for commonly connecting the first and second drive individual electrodes 43, 45.
1 and flexible substrate 4 having sensor connection pattern 53
The object of the present invention is not limited to 7, and the object of the present invention can be achieved even by common connection by soldering or the like using, for example, a conductive wire, a conductive foil, or another flexible connecting member. The configuration of the piezoelectric vibration plate 11 according to the present invention and the ultrasonic motor using the same are merely examples, and can be implemented by a conventionally known ultrasonic motor. It can also be implemented in a configuration. In a reciprocating motor, a thin and thin piezoelectric vibrating plate is simply used.

[0022]

As described above, according to the manufacturing method of the present invention, a plurality of independent first and second polarizing electrodes are formed opposite to each other on both surfaces of a piezoelectric vibrating plate element forming a piezoelectric vibrating plate. A first polarization electrode on one side is alternately connected to a different polarization potential, and a second polarization electrode opposite to the first polarization electrode is connected to a different polarization potential in the reverse order to that of the first polarization electrode. Since the second polarization electrode is electrically connected in common by a flexible connecting member after the polarization is applied, the first and second polarization electrodes are applied to the piezoelectric vibrating plate element by a single polarization voltage application. Thickness polarization in different directions can be alternately applied to the two polarization electrodes. For this reason, it is not necessary to return the polarization deterioration, which simplifies the polarization processing and suppresses the polarization variation. In addition, even if cracks occur in the piezoelectric diaphragm when incorporated in the ultrasonic motor, the cracks in the first and second polarizing electrodes are not promoted, and no further electric discharge is generated. Smooth rotation can be ensured, and the common connection state of the second polarization electrodes can be directly used for assembling the ultrasonic motor, so that the efficiency of assembling the ultrasonic motor is good.

[Brief description of the drawings]

FIG. 1 is a fragmentary cross-sectional view (I in FIG. 2) illustrating a main step of a method for manufacturing a piezoelectric diaphragm for an ultrasonic motor according to the present invention.
-I section).

FIG. 2 is a plan view showing one step of a method for manufacturing a piezoelectric diaphragm for an ultrasonic motor according to the present invention.

FIG. 3 is a plan view showing one step of a method for manufacturing a piezoelectric diaphragm for an ultrasonic motor according to the present invention.

FIG. 4 is a plan view showing a flexible substrate as an example of a flexible connection member to be superimposed on the piezoelectric vibration plate of FIG.

FIG. 5 is a schematic half sectional view showing a state in which a piezoelectric diaphragm manufactured according to the present invention is overlaid on an elastic body of an ultrasonic motor.

FIG. 6 is a half sectional view showing an example of an ultrasonic motor using a piezoelectric diaphragm.

FIG. 7 is a plan view showing one surface of a conventional piezoelectric vibration plate.

FIG. 8 is a plan view showing the other surface of the conventional piezoelectric vibration plate.

FIG. 9 is a partial cross-sectional view of a main part showing a polarization step of a conventional piezoelectric diaphragm.

FIG. 10 is a partial cross-sectional view of a main part showing a polarization step of a conventional piezoelectric diaphragm.

FIG. 11 is a partial cross-sectional view of a main part showing a polarization step of a conventional piezoelectric diaphragm.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 bearing 3 base 5 concave portion 7 convex ring portion 9 elastic body 11 piezoelectric vibration plate 13 piezoelectric vibration plate element 15 first polarization region 17 second polarization region 19, 21 common drive electrode 23 sensor electrode 25 flexible printed circuit board 27 Individual electrode (first polarization electrode) 29 Case 31 Bearing 33 Bearing 35 Shaft 37 Rotating body 39 Flange 41 Belleville spring 43 First drive individual electrode (second polarization electrode) 45 Second drive individual Electrode (second polarization electrode) 47 Flexible substrate (flexible connection member) 49 First connection pattern 51 Second connection pattern 53 Sensor connection pattern

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H02N 2/00

Claims (1)

(57) [Claims] A step of forming a plurality of first polarizing electrodes on one side of a thin plate-shaped piezoelectric diaphragm element forming a piezoelectric diaphragm at intervals, and a second step of forming a second polarizing electrode on an opposing surface of the piezoelectric diaphragm element; Forming a plurality of polarizing electrodes so as to overlap with each other at the same pitch as the first polarizing electrode; and alternately connecting different polarizing potentials to the first polarizing electrode and forming the second polarizing electrode. A polarization voltage is applied to the electrodes in a state in which the different polarization potentials are connected alternately in the reverse order to the first polarization electrode side, and polarizations having different directions with respect to the thickness direction of the piezoelectric diaphragm element are formed. Alternately applying, and after applying the polarization, connecting the second polarization electrode to a flexible contact.
And a step of electrically connecting them by a connecting member .