JPH08228493A - Manufacture of ultrasonic motor - Google Patents

Abstract

PURPOSE: To remove the influence of the difference of bonding positions and get equal performance low in dispersion among products, by so setting the number of the electrodes of a piezoelectric elements and the number of the comb teeth of an oscillator as to be severally minimum integers undivided by each other, and bonding them each in optional circumferential positions. CONSTITUTION: A piezoelectric element 2, where fan-shaped electrode patterns 2a-2d made by the equal division (for example, two times 4) in circumferential direction are provided on one side, is bonded in optional circumferential direction to the oscillator 1 having comb teeth 1a of the number being the minimum integer undivided by the number of electrode patterns 2a-2d and vice versa. In this case, the piezoelectric element 2 is bonded to the oscillator 1, being positioned, with each circumferential form as a guide or with each center hole as a guide. Hereby, even if the piezoelectric element 2 and the oscillator 1 are bonded to each other in any circumferential position, they are slid by one tooth at a time, so the progressive waves become averaged ones, and equal performance low in dispersion among products by the slippage of bonding position can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an ultrasonic motor which can obtain uniform performance without variations in characteristics.

[0002]

2. Description of the Related Art In a conventional ultrasonic motor, a piezoelectric element is bonded to one surface of the ultrasonic motor, and the other surface is provided with comb teeth so as to form irregularities in the circumferential direction. It consisted of a moving body that was pressed against. Such an ultrasonic motor is one that applies an electric signal to a piezoelectric element to generate a flexural traveling wave in a vibrating body and uses this lateral amplitude to rotate a moving body. It had a role of extracting a large amplitude without affecting the traveling wave.

[0003]

In such an ultrasonic motor, the efficiency is increased by the comb teeth provided on the vibrating body. However, the efficiency changes depending on the mutual positional relationship between the comb teeth and the electrode pattern of the piezoelectric element. Had the problem of doing.

For example, in FIG. 4, the vibrating body 1 is provided with 24 comb teeth 1a, and the convex portions of the respective comb teeth are indicated by diagonal lines. On the back surface of the piezoelectric element 2, electrode patterns 2a to 2d equally divided in the circumferential direction are provided, the regions of the two adjacent electrode patterns 2a and 2b are polarized in the positive direction, and then the two adjacent electrode patterns 2c. , 2d are polarized in the negative direction.

The lead wires 5 attached to each of the electrode patterns 2a to 2d are bundled into groups 5a and 2b of 2a and 2c and groups 5b of 2d every other, and the lead wires 5a and 5b are temporally 90 °. Add signals with different phases. As a result, a flexural traveling wave is generated in the vibrating body 1. Even though the traveling wave is a traveling wave, the standing wave of the group of lead wires 5a and the standing wave of the group of lead wires 5b are combined.

This state will be described with reference to the deflection state of the standing wave shown in FIG. In the figure, a standing wave generated by the group of electrode patterns 2a and 2c is indicated by A, and a standing wave generated by the group of electrode patterns 2b and 2d is indicated by B. The vibrating body 1 has 24 comb teeth and is bonded in such a manner that the centers of the convex portions 1e of the comb teeth and the centers of the electrode patterns 2a to 2d coincide with each other. In this case, since the position of the maximum bending point C (12 places) and the convex portion overlap, the bending rigidity is large and the deflection is small. Therefore, the amplitude of the vibrating body 1 is reduced, and the rotational force transmitted to the moving body is also reduced.

On the other hand, as shown in FIGS. 6 and 7, if the centers of the concave portions 1f of the comb teeth and the centers of the electrode patterns 2a to 2d are adhered to each other, the maximum bending point C
Since (12 places) overlaps with the concave part, the bending rigidity becomes small and it bends greatly. Therefore, the amplitude of the vibrating body 1 becomes relatively large, and the rotational force transmitted to the moving body also becomes large.

As described above, there is a problem that the efficiency of the ultrasonic motor changes greatly due to the variation in the bonding position between the vibrating body 1 and the piezoelectric element 2.

[0009]

In order to solve the above problems, according to the present invention, the number of electrodes of the piezoelectric element and the number of concavities and convexities of the comb teeth of the vibrator are set to be relatively prime, and each of them is set to an arbitrary value. By bonding at the circumferential position, it is possible to obtain an ultrasonic motor of uniform performance that is not affected by the difference in the bonding position and has little variation among products.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a piezoelectric element, a vibrating body having one surface to which the piezoelectric element is adhered, and the other surface provided with a toothless portion so as to form irregularities in the circumferential direction. An ultrasonic motor manufacturing method in which a moving body is pressed against the upper surface of a comb tooth and frictionally drives the moving body by a flexural traveling wave that uses the expansion and contraction motion of a piezoelectric element. And a piezoelectric element provided with a fan-shaped electrode pattern formed thereon is bonded to the vibrating body having comb tooth irregularities whose number is relatively prime to the number of the electrode patterns at an arbitrary circumferential position. .

It is sufficient for the above-mentioned piezoelectric element to use the outer peripheral shape of the vibrating body as a positioning guide in the bonding step. Alternatively, each center hole may be used as a positioning guide. The fan-shaped electrode pattern of the piezoelectric element may be formed by being divided into multiples of 4, and the division may be performed by dividing the entire circumference at equal intervals.

Further, all the fan-shaped electrode patterns of the piezoelectric element may be driving electrode patterns.
With the above-described configuration, no matter how the piezoelectric element and the vibrating body are bonded at any circumferential position, the center of the concave or convex portion of the comb teeth of the vibrating body and the center of the electrode pattern of the piezoelectric element are all around. The strength of the standing wave may vary depending on the location within a single product because the values do not match over each other and gradually shift for each tooth, but the traveling waves resulting from the synthesis are averaged. As a result, there is no variation in performance between products due to the displacement of the bonding position.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of an ultrasonic motor according to the present invention, in which a piezoelectric element 2 is bonded to a vibrating body 1 and a comb tooth 1 is provided on the opposite side.
a is provided. The moving body 3 is a pressure spring 4 and is a vibrating body 1.
Being pressed against. The lead wire 5 is soldered to an electrode on the back surface of the piezoelectric element 2. Here, when an electric signal is applied to the piezoelectric element 2 from the lead wire 5, a flexural traveling wave is generated in the vibrating body 1 to rotate the moving body 3.

FIG. 2 is a view showing the positional relationship between the electrodes of the piezoelectric element 2 according to the present invention and the comb teeth 1a of the vibrating body 1. The vibrating body 1 is provided with 25 comb teeth 1a. The convex portions of are indicated by diagonal lines. On the back surface of the piezoelectric element 2, electrode patterns 2a to 2d equally divided in the circumferential direction are provided, the regions of the two adjacent electrode patterns 2a and 2b are polarized in the positive direction, and then the two adjacent electrode patterns 2c. , 2d are polarized in the negative direction.

The lead wires 5 attached to each of the electrode patterns 2a to 2d are bundled into groups 5a and 2b of 2a and 2c and groups 5b of 2d every other, and the lead wires 5a and 5b are temporally 90 °. Add signals with different phases. As a result, a flexural traveling wave is generated in the vibrating body 1. Even though the traveling wave is a traveling wave, the standing wave of the group of lead wires 5a and the standing wave of the group of lead wires 5b are combined.

This situation will be described with reference to the deflection state of the standing wave according to the present invention shown in FIG. In the figure, a standing wave generated by the group of electrode patterns 2a and 2c is indicated by A, and a standing wave generated by the group of electrode patterns 2b and 2d is indicated by B. The number of comb teeth of the vibrator 1 is 25
Considering, for example, a case where the center of one of the electrode patterns 2a (the portion indicated by [2a]) and the center of the convex portion 1b in the comb tooth are bonded so as to coincide with each other, the maximum bending point C
Although 1 coincides with the convex portion 1b, the center of C2 is displaced by a 1/12 pitch, the center is displaced by 2/12 in C3, and by 3/12 in C4. Since the positional relationship is such that the concave portion 1c coincides with C7, and the positional deviation is 1/12 pitch with C8, the bending rigidity of the vibrating body 1 at the maximum bending point gradually changes in the circumferential direction.

At this time, if the bonding position of the piezoelectric element 2 and the vibrating body 1 is displaced, the above positional relationship is slightly different. However, when the displacement of the bonding position reaches 1/12 pitch, the maximum bending point C2 is a convex portion. It comes to coincide with 1d and returns to the same state as in FIG. As described above, even if the piezoelectric element 2 is randomly bonded to the vibrating body 1 during the manufacture of the ultrasonic motor, only a deviation of 1/12 pitch occurs, and this is a variation of the standing wave. , The traveling wave as a result of synthesizing the whole is in an averaged form,
The characteristics will hardly change.

When the piezoelectric element 2 is adhered to the vibrating body 1, as shown in FIG. 1, the positioning guide is provided so that the outer peripheral shape of the vibrating body 1 and the outer peripheral shape of the piezoelectric element 2 coincide or are concentric. You can do it. Alternatively, positioning guide may be performed so that the center hole of the vibrating body 1 and the center hole of the piezoelectric element 2 are concentric. In any of the guiding methods, the circumferential position may be arbitrary as long as the radial direction can be positioned.

In the present embodiment, the case where the number of comb teeth is 25 with respect to the number of 12 electrode patterns is shown, but the same effect can be obtained with any number of combinations as long as they are coprime. can get.

[0020]

As described above, according to the present invention, no matter how the piezoelectric element and the vibrating body are bonded at the circumferential position, the center of the concave or convex portion of the comb teeth of the vibrating body and the electrode of the piezoelectric element Since the center of the pattern does not coincide with the entire circumference and it shifts little by little for each tooth, the strength of the standing wave may change depending on the location within one product, but the result of the synthesis is Has an effect that an ultrasonic motor having uniform performance with less variation among products due to displacement of the bonding position can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of an ultrasonic motor according to the present invention.

FIG. 2 is a diagram showing a positional relationship between electrodes and comb teeth according to the present invention.

FIG. 3 is a diagram showing a bending state of a standing wave according to the present invention.

FIG. 4 is a diagram showing an example of a positional relationship between electrodes and comb teeth in a conventional ultrasonic motor.

5 is a diagram showing a bending state of a standing wave in the positional relationship between the electrode and the comb tooth of FIG.

FIG. 6 is a diagram showing another example of the positional relationship between electrodes and comb teeth in a conventional ultrasonic motor.

FIG. 7 is a diagram showing a bending state of a standing wave in the positional relationship between the electrodes and the comb teeth of FIG.

[Explanation of symbols]

 1 Vibrating body 2 Piezoelectric element 3 Moving body 4 Pressure spring 5 Lead wire

Claims (6)

[Claims] 1. A piezoelectric element, a vibrating body having one surface on which the piezoelectric element is adhered, and an opposite surface provided with comb teeth so as to form irregularities in the circumferential direction, and pressed onto the upper surface of the comb tooth of the vibrating body. In a method of manufacturing an ultrasonic motor in which a moving body is frictionally driven by a flexural traveling wave utilizing the expansion and contraction movement of the piezoelectric element, a fan-shaped electrode pattern divided into one surface at equal intervals in the circumferential direction. And a step of bonding the piezoelectric element provided with the piezoelectric element at an arbitrary circumferential position to the vibrating body having comb tooth irregularities that are relatively prime to the number of the electrode patterns. Method of manufacturing acoustic wave motor. 2. The method of manufacturing an ultrasonic motor according to claim 1, wherein the piezoelectric element is adhered to the vibrating body by using respective outer peripheral shapes as positioning guides. 3. The piezoelectric element is adhered to the vibrating body by using its center hole as a positioning guide.
A method for manufacturing the described ultrasonic motor. 4. The method of manufacturing an ultrasonic motor according to claim 1, wherein the fan-shaped electrode pattern of the piezoelectric element is formed by being divided into multiples of four. 5. The method of manufacturing an ultrasonic motor according to claim 1, wherein the fan-shaped electrode pattern of the piezoelectric element is formed by dividing the entire circumference at equal intervals. 6. The method of manufacturing an ultrasonic motor according to claim 1, wherein all of the fan-shaped electrode patterns of the piezoelectric element are driving electrode patterns.