JP3141210B2 - 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 a so-called ultrasonic motor using ultrasonic vibration of a piezoelectric vibrator used in OA equipment and the like, and more particularly to a hollow cylindrical ultrasonic motor having a simple structure.

[0002]

2. Description of the Related Art FIG. 4 is a perspective view showing an example of the configuration of a conventional ultrasonic motor. In FIG. 4, the ultrasonic motor is a so-called longitudinal-torsional type, in which a vibration node of the longitudinal-torsional composite vibrator 110 is fixed by a support ring 111, and a rotor 112 rotatably supported on at least one end face is pressurized. It is configured to be in contact.

FIG. 5 is a perspective view showing another configuration example of a conventional ultrasonic motor. In FIG. 5, the ultrasonic motor is of a so-called torsion-spread type, and a torsion-spread composite vibrator 11 is used.
The contact point of the vibration of 0 'is fixed by a support ring 111', and a tapered or cup-shaped rotor 112 'rotatably supported on at least one end face is brought into pressure contact.

[0004]

In the conventional longitudinal-twisted composite vibrator 111 or torsion-spread composite vibrator 111 'shown in FIGS. 4 and 5, the respective end faces of the piezoelectric ceramics and the rotor 112 or 112 are used. 'Is not always uniform and the rotation is not smooth.

Accordingly, a technical object of the present invention is to eliminate the above-mentioned drawbacks of the conventional longitudinal-torsional composite vibrator or torsional-spread composite vibrator, and to achieve a smooth rotation and a good vertical-torsional rotation conversion efficiency. It is an object of the present invention to provide an ultrasonic motor using a composite vibrator or a torsional-spread composite vibrator.

[0006]

According to the present invention, a torsional vibrating portion that performs torsional vibration is provided on a part of the outer peripheral surface of a hollow column of piezoelectric ceramics, at both ends of the torsional vibrating portion in either a radial direction or an axial direction. A piezoelectric composite vibrator provided with a telescopic vibrating part that performs telescopic vibration in one direction; a wear-resistant member layer provided at both ends of the piezoelectric composite vibrator; An ultrasonic motor including a pair of rotors, first and second shafts inserted from both ends of the piezoelectric composite vibrator and rotatably supporting the pair of rotors; Thus, there is provided an ultrasonic motor comprising a coupling member made of an elastic body for connecting the first shaft and the second shaft.

In the present invention, the term "torsional vibrator" refers to a vibrator that performs torsional vibration such that both end faces of a hollow piezoelectric ceramic cylinder rotate in opposite directions. In the present invention, it is preferable that the torsional vibrating portion is formed by applying a plurality of oblique electrodes to a part of a hollow column made of a piezoelectric ceramic in the longitudinal direction and using the oblique electrodes as two terminals to be polarized. .

Further, in the present invention, the expansion and contraction vibrating portion that performs expansion and contraction vibration in one of the radial direction and the axial direction of the hollow column of the piezoelectric ceramic is defined as a vertical oscillator that performs expansion and contraction vibration in the length direction or a radial oscillator in the radial direction. It refers to a device having the same configuration as a spreading oscillator that performs spreading vibration.

That is, as an example of a vertical vibrator, interdigital electrodes are formed in a direction parallel to the circumferential direction of a hollow piezoelectric ceramic column, and each has two terminals. There is a type in which a column is polarized, and an AC voltage is applied between each interdigital electrode to enable longitudinal vibration to be excited near the end of the piezoelectric ceramic hollow cylinder. It can be used as a child.

[0010] On the other hand, in the present invention, as an example of the spreading vibrator, interdigital electrodes are formed in a direction parallel to the length direction of the hollow column of piezoelectric ceramics, and each has two terminals. And a piezoelectric ceramic hollow cylinder is subjected to a polarization treatment, and an alternating voltage is applied between each interdigital electrode to allow the piezoelectric ceramic hollow cylinder to expand and excite vibrations. It can be used as a child.

Further, according to the present invention, there is provided a bending vibrator in which both end surfaces of a piezoelectric ceramic hollow cylinder perform an elliptical motion vibration,
In an ultrasonic motor including a wear-resistant member layer provided at both ends of the bending oscillator and a pair of rotors pressed against the wear-resistant member layer, the ultrasonic motor is inserted from both ends of the bending oscillator. And a first and second shaft rotatably supporting the pair of rotors, respectively, and a coupling member made of an elastic body connecting the first and second shafts in the piezoelectric composite vibrator. Thus, an ultrasonic motor is obtained.

Here, in the present invention, the term "bending vibrator" refers to a bending vibrator that performs bending vibration and whose both end surfaces perform elliptical motion vibration. In the present invention, as an example of a bending vibrator, a plurality of circumferential electrode pairs are provided in parallel with the circumferential direction on each small portion obtained by dividing an outer peripheral surface of a piezoelectric ceramic hollow cylinder into a plurality in the circumferential direction. An electrode formed by performing polarization using the peripheral electrode pair as two terminals can be given.
On the other hand, as another example of the bending vibrator, a plurality of vertical electrode pairs are provided in parallel with the length direction of the hollow column of the piezoelectric ceramics, and the vertical electrode pairs are polarized as two terminals. An example in which an alternating voltage having a frequency equal to the resonance frequency is applied to perform bending vibration can be given.

[0013]

According to the ultrasonic motor of the present invention, an integrated vertical motor
Since the torsional composite vibrator or the integrated torsional-spread composite vibrator is a hollow cylinder, the first shaft and the second shaft for rotatably supporting the rotor are inserted into the center from both sides, and the elastic body is used. They are connected with the resulting coupling. Two rotors are pressed against the wear-resistant material at the same time on the integrated longitudinal-torsional composite vibrator and the integrated torsional-spread composite vibrator, and the elastic body stabilizes the contact state of the friction surface, making the rotation smoother and more stable. An ultrasonic motor of a rotating type can be realized.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a partially cutaway front view showing an example of the structure of an ultrasonic motor according to the present invention. As shown in FIG.
The ultrasonic motor is composed of an abrasion-resistant member 2 at both ends of an integrated longitudinal-torsional composite vibrator or an integrated torsional-spread composite vibrator 20.
7, 27 'are joined, and the rotors 28, 28' are pressed. At this time, the first shaft 29 and the second shaft 29 'passing through the inside of the hollow cylinder are joined by a coupling member 51 made of an elastic material inside the hollow cylinder. In the case where a bending vibrator 30 or 40 described below is used instead of the integrated longitudinal-torsional composite vibrator or the integrated longitudinal-torsional composite vibrator 20 of FIG. The wear-resistant members 27, 27 'are in contact with the end faces of the rotors 29, 29'.
8 ′ is pressed. As described above, the shafts 29 and 29 'passing through the inside of the hollow cylinder are joined by a coupling 51 made of an elastic material inside the hollow cylinder.

FIG. 2 is a perspective view showing an example of the configuration of an integrated longitudinal-torsional composite vibrator or an integrated torsional-spread composite vibrator 20 used in the ultrasonic motor of FIG. A plurality of electrodes 21 and 22 are formed at the center of the outer peripheral surface of the piezoelectric ceramic hollow cylinder 20 at 45 ° with respect to the longitudinal direction of the piezoelectric ceramic hollow cylinder and intersect with each other. 'And 22' to form a cross finger electrode, thereby forming a torsional vibrator. Further, a plurality of electrodes 23, which extend in parallel to the circumferential direction of the piezoelectric ceramic hollow cylinder and intersect with each other on the outer peripheral portions of both ends of the interdigital electrode having a 45 ° inclination of the torsional vibrating portion, intersect with each other. 24, 25, and 26 are formed, respectively, and the electrodes of the same number are connected to the connection electrodes 23a, 26, respectively.
a, a longitudinal vibration part or a torsional vibration part is formed.

The piezoelectric ceramic hollow cylinder is manufactured by a usual press molding technique, and is formed by applying electrode printing, which is also a general technique, to the outer peripheral surface thereof. In FIG. 2, a high DC voltage is applied between the common electrodes 21 'and 22', and the piezoelectric ceramic hollow cylindrical electrodes 21 'and 2' are applied.
When an alternating voltage having a frequency equal to the resonance frequency of the composite vibrator is applied after performing the polarization process between 2 ′, the piezoelectric ceramic hollow cylinder 20 is polarized when the polarity of the voltage is the same as the polarity of the voltage at the time of polarization. When the polarity of the voltage is opposite to the polarity of the voltage at the time of polarization, a contraction strain occurs in the direction of the polarization. As a result, resonance occurs so that both ends are twisted. Similarly, between the interdigital electrodes 23 and 24 and 2
When a DC high voltage is applied between 5 and 26, the polarization direction is a direction perpendicular to the length direction of the interdigital electrodes 23, 24 and 25 and 26,
That is, it is the length direction of the hollow cylinder. When a voltage is applied to the interdigital electrode in this state, if the polarity of the voltage is the same as the voltage at the time of polarization, stretching strain occurs in the direction of polarization, and if the polarity of the voltage is opposite to the polarity of the voltage at the time of polarization, Shrinkage strain occurs in the direction of polarization. In other words, the expansion and contraction displacement in the length direction of the hollow cylinder is generated, and the expanding displacement in the radial direction of the hollow cylinder is generated. After the polarization treatment, an AC voltage equal to the torsional resonance frequency is applied to the piezoelectric ceramic hollow cylinder 2.
Numeral 0 indicates longitudinal vibration or spreading vibration at the torsional resonance frequency.

FIG. 3A is a perspective view showing an example of a spreading oscillator as an example of a bending oscillator used in the ultrasonic motor according to the embodiment of the present invention. FIG. 3A shows vertical electrodes 31, 32, 33. Parallel to the length direction of the piezoelectric ceramic hollow cylinder on the outer peripheral surface of the piezoelectric ceramic hollow cylinder 30.
34, 35, 36, 37 and 38 are formed, and common electrodes 31 'and 32', 33 'and 34', 35 'and 36', respectively.
37 'and 38'.

In FIG. 3 (a), when a DC high voltage is applied between the common electrodes 31 'and 32' and 35 'and 36' to perform polarization processing, the polarization direction is in the length direction of the interdigital electrode. It is a right angle direction. When an AC voltage having a frequency equal to the resonance frequency of the bending oscillator is applied, if the polarity of the voltage is the same as the polarity of the voltage at the time of polarization, an elongation strain occurs in the direction of polarization, and if the polarity of the voltage is opposite, Then, contraction strain occurs in the polarization direction, and the piezoelectric ceramic hollow cylinder 30 undergoes bending vibration. Similarly, between the common electrodes 33 'and 34' and 37 'and 3
A high DC voltage is applied between 8 'and the interdigital electrodes 33 and 3
After the polarization process is performed between the portions 4 and 37 and 38, if an AC voltage equal to the resonance frequency of the bending oscillator is applied, the piezoelectric ceramic hollow cylinder 30 bends and vibrates in a direction perpendicular to the previous vibration direction. Here, the cross finger electrodes 31 ', 3
The same voltage as that of the voltage at the time of polarization is applied to 2 ′, and a voltage having a polarity opposite to the polarity of the voltage at the time of polarization is applied to the interdigital electrodes 35 and 36. That is, in the length direction of the hollow cylinder, the side of the interdigital electrodes 31, 32 contracts, while the interdigital electrodes 35,
A bending displacement in which the side 36 extends is generated. The interdigital electrode 3
The same voltage as the polarity of the voltage at the time of polarization is applied to 3, 34, and the voltage opposite to the polarity at the time of polarization is applied to the interdigital electrodes 37, 38.

That is, in the longitudinal direction of the hollow cylinder, a bending displacement occurs in which the interdigital electrodes 33 and 34 contract and the interdigital electrodes 37 and 38 extend. Therefore, the interdigital electrodes 31, 32, 33, 34 and the interdigital electrodes 35, 3
When an AC voltage having a phase difference of 90 ° is applied to 6, 37, and 38, the end face of the hollow cylinder undergoes elliptical motion while performing bending vibration in the longitudinal direction of the hollow cylinder. This bending oscillator is
When used in place of the composite vibrator shown in FIG. 1, an ultrasonic motor similar to that shown in FIG. 1 can be obtained.

FIG. 3B is a diagram showing a vertical vibrator as another example of the bending vibrator used in the ultrasonic motor according to the embodiment of the present invention. FIG. 3B shows a plurality of electrodes 41, 42, 43, 44, 45, 46, 47 formed on the outer peripheral surface of the piezoelectric ceramic hollow cylinder 40, which are peripheral electrodes crossing each other in parallel to the circumferential direction of the piezoelectric ceramic hollow cylinder. 48 are formed, and the common electrodes 41 'and 42', 43 'and 4 are respectively formed.
4 ', 45', 46 'and 47', 48 '. In FIG. 3B, when a DC high voltage is applied between the common electrodes 41 'and 42' and between 45 'and 46' to perform polarization, the polarization direction becomes the length of the interdigital electrode. The direction is perpendicular to the direction. When an AC voltage having a frequency equal to the resonance frequency of the bending oscillator is applied, if the polarity of the voltage is the same as the polarity of the voltage at the time of polarization, an elongation strain occurs in the direction of polarization, and if the polarity of the voltage is opposite, Then, contraction strain is generated in the polarization direction, so that the piezoelectric ceramic hollow cylinder 40 undergoes bending vibration.

Similarly, between the common electrodes 43 'and 44' and between 47 'and 48', ie, the interdigital electrodes 43 and 4 '.
After applying a DC high voltage between the electrodes 4 and 47 and 48 to perform polarization processing, and applying an AC voltage equal to the resonance frequency of the bending vibrator, the piezoelectric ceramic hollow cylinder 40 can be obtained.
Vibrates in a direction perpendicular to the previous vibration direction. here,
The same voltage as the polarity of the voltage at the time of polarization is applied to the interdigital electrodes 41 and 42, and a voltage having a polarity opposite to the polarity of the voltage at the time of polarization is applied to the interdigital electrodes 45 and 46. That is, in the length direction of the hollow cylinder, a bending displacement occurs in which the cross finger electrodes 41 and 42 contract and the cross finger electrodes 45 and 46 expand. A voltage having the same polarity as the polarity during polarization is applied to the interdigital electrodes 43 and 44, and a voltage having a polarity opposite to the polarity during polarization is applied to the interdigital electrodes 47 and 48.
That is, in the length direction of the hollow cylinder, a bending displacement occurs in which the cross finger electrodes 43 and 44 contract and the cross finger electrodes 47 and 48 expand. Therefore, the interdigital electrodes 41, 4
2, 43, 44 and the interdigital electrodes 45, 46, 47, 4
When an AC voltage having a phase difference of 90 ° is applied between the end face of the hollow cylinder and the end face of the hollow cylinder, the end face of the hollow cylinder vibrates in an elliptical motion while performing bending vibration in the longitudinal direction of the hollow cylinder. This bending oscillator is shown in FIG.
When the composite vibrator of the ultrasonic motor shown in FIG. 1 is used in place of the composite vibrator shown in FIG. 1A, an ultrasonic motor similar to that shown in FIG. 1 is obtained.

Therefore, according to the structure of the ultrasonic motor of the present invention, the first shaft 29 connected by the elastic body 51 is provided.
By providing a degree of freedom on the rotor 28 side by the second shaft 29 'and the second shaft 29', the contact state of the friction surface becomes stable and the rotation becomes smooth.

[0023]

As described above, according to the present invention, according to the present invention, it is generally applied as a vertical vibrator for an ultrasonic motor or a composite vibrator having a spreading vibrator and a torsional vibrator or a bending vibrator. Using a piezoelectric ceramic hollow cylinder that can be easily manufactured by the press molding technology, the outer peripheral surface is subjected to electrode printing, which is also a common technique, to produce a longitudinal oscillator, a spreading oscillator, and a torsional oscillator. Integrated or vertical torsion composite vibrator and integrated torsion, which are easy to manufacture because the composite vibrator or flexural vibrator with vibrator is obtained as an integral molding A spreading ultrasonic motor or a hollow cylindrical bending vibration ultrasonic motor can be obtained.

Further, according to the present invention, since the shape of the integrated longitudinal-torsional composite vibrator, the integrated torsional-spread composite vibrator or the hollow cylindrical bending vibrator is a hollow cylinder,
By using a coupling made of an elastic body with a shaft penetrating the center part, an ultrasonic motor of a system in which two rotors are simultaneously pressed against a wear-resistant material and stably rotated can be realized.

As described above, according to the present invention, the ultrasonic motor is constituted by using the integrated longitudinal-torsional composite vibrator, the integrated torsional-spread composite vibrator or the hollow cylindrical bending vibrator.
An ultrasonic motor with a simple structure and small variations in characteristics can be obtained, and the practical effect is great.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view showing a configuration example of an ultrasonic motor according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a configuration example of an integrated vertical-torsional composite vibrator or an integrated torsional-spread composite vibrator used in the ultrasonic motor of FIG. 1;

FIG. 3A is a perspective view illustrating an example of a bending oscillator of the ultrasonic motor according to the embodiment of the present invention. (B) is a perspective view showing another example of the bending oscillator of the ultrasonic motor according to the embodiment of the present invention.

FIG. 4 is a perspective view showing a configuration example of a conventional ultrasonic motor.

FIG. 5 is a perspective view showing another configuration example of a conventional ultrasonic motor.

[Explanation of symbols]

20 Integral longitudinal-torsional composite vibrator or integral torsional-
Spreading composite vibrator 20 'Piezoelectric ceramic hollow cylinder 21 electrode 22 electrode 23 electrode 23a connection electrode 25 electrode 26 electrode 26a connection electrode 21' common electrode 22 'common electrode 27 wear-resistant member 27' wear-resistant member 28 rotor 28 'rotor 29 Shaft 29 'Shaft 30 Hollow cylindrical bending oscillator 40 Hollow cylindrical bending oscillator 31 Electrode 32 Electrode 33 Electrode 34 Electrode 35 Electrode 36 Electrode 37 Electrode 38 Electrode 31' Common electrode 32 'Common electrode 33' Common electrode 34 'Common Electrode 35 'common electrode 36' common electrode 37 'common electrode 38' common electrode 41 electrode 42 electrode 43 electrode 44 electrode 45 electrode 46 electrode 47 electrode 48 electrode 41 'common electrode 42' common electrode 43 'common electrode 44' common electrode 45 'Common electrode 46' Common electrode 47 'Common electrode 48 'common electrode 51 coupling 110 vertical - torsional composite transducer 110' twisting - spread composite transducer 111 support ring 111 'supporting ring 112 Rotor 112' Rotor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-311181 (JP, A) JP-A-3-15279 (JP, A) JP-A-3-40765 (JP, A) JP-A-3-301 40766 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H02N 2/16

Claims (2)

(57) [Claims] 1. A torsional vibrator for performing a torsional vibration on a part of the outer peripheral surface of a hollow column of piezoelectric ceramics, and elastic vibrations for performing an elastic vibration in one of a radial direction and an axial direction at both ends of the torsional vibrator. An ultrasonic wave comprising: a piezoelectric composite vibrator provided with respective portions; a wear-resistant member layer provided at both ends of the piezoelectric composite vibrator; and a pair of rotors respectively pressed against the wear-resistant member layer. In the motor, first and second shafts inserted from both ends of the piezoelectric composite vibrator and rotatably supporting the pair of rotors, and the first shaft and the second shaft in the piezoelectric composite vibrator. An ultrasonic motor comprising: a coupling member made of an elastic body that connects the shaft to the shaft. 2. A bending vibrator in which both end surfaces of a piezoelectric ceramic hollow cylinder perform an elliptical motion vibration, a wear-resistant member layer provided at both ends of the bending vibrator, and a pressure contact with the wear-resistant member layer. An ultrasonic motor having a pair of rotors, the first and second rotors being inserted from both ends of the bending vibrator and rotatably supporting the pair of rotors, respectively.
And a coupling member formed of an elastic body that connects the first and second shafts in the piezoelectric composite vibrator.