JP2003052184A - Ultrasonic motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic motor which can detect turning position of rotor, while controlling increase in the allocation space in the ultrasonic motor for driving the rotor to turn mainly with a plurality of axes. SOLUTION: A stator 4 has first to third piezoelectric elements 11 to 13, which generate vibration in different directions to a contact part 9b and generates vibration in a plurality of directions to a contact part 9a through a combination of vibrations in two directions. A rotor 5 turns about a plurality of axes respectively, based on the vibrations in a plurality of directions generated in the contact part 9b. The rotor 5 includes a position detector 51, which displaces vibration reflected to the stator 4 depending on the turning position. A high-frequency signal is supplied to any of the piezoelectric elements 11 to 13 to generate vibration to the contact part 9b, and the high-frequency signal reflected to the stator 4 from the rotor 5 is detected with any of piezoelectric element 11 to 13 which does not generate vibration to the contact part 9b, in order to detect the turned position of the rotor 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic motor for rotatably driving a rotor about a plurality of axes, and more particularly to an ultrasonic motor capable of detecting the rotational position of a rotor.

[0002]

2. Description of the Related Art In recent years, ultrasonic motors have been proposed which rotate a rotor about a plurality of axes. For example, tribologist (Vol. 40, No. 8 (1995) 627-631)
Describes an ultrasonic motor in which a plurality of shafts are arranged orthogonal to each other with respect to a spherically formed rotor.
This ultrasonic motor is provided with a plurality of stators that respectively generate vibrations about respective one-axis centers and rotationally drive the rotors through frictional forces, and these stators move (rotate) about the plurality of axis centers of the rotors. Has been realized. Since this ultrasonic motor requires a plurality of stators and the like to generate vibration, the size of the device is inevitably increased.

Therefore, an ultrasonic motor has been proposed in which vibration of a plurality of axes is generated with respect to a single stator and the rotor is rotationally driven by frictional force. For example, a plurality of piezoelectric elements for generating vibration around a plurality of axes are laminated on a stator of this ultrasonic motor, and these piezoelectric elements realize movement (rotation) of the rotor about the plurality of axes. .

[0004]

By the way, it is conceivable that the ultrasonic motor as described above is mounted and operated in, for example, an animal toy robot. Then, for example, when the stator of the ultrasonic motor is arranged on the body of the animal toy robot and the driven member connected to the rotor is used as the limb, the rotational position of the rotor corresponding to the position of the limb is detected. There is a need to.

However, when a dedicated sensor for detecting the rotational position of the rotor is separately provided, it causes an increase in the arrangement space. An object of the present invention is to provide an ultrasonic motor that rotationally drives a rotor around a plurality of axes,
An object of the present invention is to provide an ultrasonic motor capable of detecting the rotational position of the rotor while suppressing an increase in the arrangement space.

[0006]

In order to solve the above problems, the invention according to claim 1 has at least three vibration generators for generating vibrations in mutually different directions at a contact portion, and any one of them is provided. A stator that combines vibrations in two directions to generate vibrations in a plurality of directions at the contact portion and a rotor that rotates about a plurality of axes based on vibrations in a plurality of directions generated at the contact portion are provided. In the ultrasonic motor, the rotor has a variation unit that varies the vibration reflected by the stator according to the rotational position, and does not generate the vibration reflected by the rotor from the rotor in the contact portion. The gist is that the rotational position of the rotor is detected by detecting with any one of the vibration generators.

According to a second aspect of the present invention, in the ultrasonic motor according to the first aspect, a high frequency signal is supplied to a vibration generator that causes the contact portion to vibrate, and is reflected from the rotor to the stator. The gist is that the rotational position of the rotor is detected by detecting the high-frequency signal by any one vibration generator that does not generate vibration at the contact portion.

According to a third aspect of the present invention, in the ultrasonic motor according to the second aspect, the high frequency signal is supplied only to any one of the vibration generators that cause the contact portion to vibrate. Use as a summary.

A fourth aspect of the present invention is based on the ultrasonic motor according to the third aspect, wherein the high frequency signal is supplied to a vibration generator on a side far from the rotor. The invention described in claim 5 is the ultrasonic motor according to any one of claims 2 to 4, wherein the high-frequency signal is a drive signal supplied to the vibration generator so as to generate vibration in the contact portion. Instead of this, the main point is that it is supplied every predetermined time.

According to a sixth aspect of the present invention, in the ultrasonic motor according to any of the second to fourth aspects, the high frequency signal is supplied to the vibration generator so as to generate vibration at the contact portion. The main point is that it is continuously supplied while being superimposed on the drive signal.

According to a seventh aspect of the present invention, the element piece is polarized at a predetermined angle in a polarization region divided by a non-polarization region arranged so as to generate longitudinal vibration at the contact portion and arranged at a predetermined angle. In the polarization region divided by non-polarization regions arranged at a predetermined angle, the first piezoelectric element having the above-mentioned structure is polarized and polarized with changing the polarity in the circumferential direction so as to generate bending vibration in the contact portion. The second piezoelectric element, in which element pieces are formed at predetermined angles, is polarized by changing the polarity in the circumferential direction so as to deviate from the second piezoelectric element by about 90 degrees so as to generate bending vibration in the contact portion. A third piezoelectric element in which element pieces are formed for each predetermined angle in a polarized region divided by a non-polarized region arranged for each angle, and two of the first to third piezoelectric elements are provided. Vibrations are combined to generate vibrations in multiple directions at the contact part. And a rotor that rotates about a plurality of axes based on vibrations in a plurality of directions generated at the contact portion. The rotor fluctuates the vibration reflected by the stator according to the rotation position. The vibration reflected from the rotor to the stator is individually controlled by each element piece formed in any one of the first to third piezoelectric elements that does not generate vibration in the contact portion. The gist is that the rotational position of the rotor is detected.

In the ultrasonic motor according to claim 7, the invention according to claim 8 supplies power to any two of the first to third piezoelectric elements to drive the vibration, and at the same time, to supply a high frequency signal to either one of the piezoelectric elements. Any one of the first to third piezoelectric elements that is not driven by a driving means that supplies the electromotive force based on the high frequency signal reflected from the rotor to the stator.
The gist of the present invention is to provide a detecting means for detecting the rotational position of the rotor by individually detecting the element pieces formed into one.

According to a ninth aspect of the present invention, in the ultrasonic motor according to the eighth aspect, the detected rotational position of the rotor is compared with the target rotational position, and when they reach substantially the same position. The gist of the present invention is to include target setting means for stopping power supply by the driving means.

The invention according to a tenth aspect is the first to ninth aspects.
In the ultrasonic motor according to any one of the above items, the fluctuating means is formed in a substantially disc shape and is provided so as to rotate integrally with the rotor.

An eleventh aspect of the present invention is based on the ultrasonic motor according to the tenth aspect, wherein the varying means has a notch in a part in the circumferential direction. The twelfth aspect of the invention is summarized in that, in the ultrasonic motor according to the tenth or eleventh aspect, the rotor is a substantially spherical body, and the changing means is housed inside the rotor.

(Operation) According to the invention described in claim 1 or 7, the rotor has the changing means for changing the vibration reflected by the stator according to the rotating position. Then, any one of the vibration generators (first
~ Third piezoelectric element), the vibration reflected from the rotor to the stator is detected to detect the rotational position of the rotor. Therefore, a special device for detecting the rotational position of the rotor is not required, the structure relating to the detection is simplified, and the increase of the installation space is suppressed.

According to the second or eighth aspect of the invention, for example, the vibration generator (first to first) for vibrating the contact portion is used.
The frequency of the high-frequency signal supplied to the third piezoelectric element is the same as that of the vibration generator (the first piezoelectric element) in order to generate vibration at the contact portion.
~ By setting the frequency sufficiently higher than the frequency of the signal (drive signal) supplied to the third piezoelectric element, the influence of the supply of the high frequency signal on the vibration of the contact portion is suppressed. Further, since it is a high frequency signal, it is easy to reflect from the rotor to the stator, and the accuracy of detecting the rotational position of the rotor is improved.

According to the invention described in claim 3 or 8, the high frequency signal is supplied only to any one of the vibration generators (first to third piezoelectric elements) that generate vibration in the contact portion. Therefore, since there is only one generation source of the high frequency signal, the disturbance signal mixed in the high frequency signal reflected from the rotor to the stator is reduced, and the detection accuracy of the rotational position of the rotor by the detection of the reflected high frequency signal is also improved. Be improved. Moreover, since it is not necessary to synchronize each signal as in the case of supplying a plurality of (for example, two) high frequency signals, the structure is simple.

According to the invention described in claim 4, the high frequency signal is supplied to the vibration generator on the side far from the rotor. Therefore, the time difference until the supplied high-frequency signal is reflected from the rotor to the stator and detected by any one of the vibration generators that does not generate vibration at the contact portion is increased accordingly. Then, the high frequency signal before reflection (supplied high frequency signal) and the high frequency signal after reflection can be easily distinguished.

According to the fifth aspect of the invention, the high frequency signal is supplied every predetermined time in place of the drive signal supplied to the vibration generator so as to generate vibration at the contact portion. Therefore, the number of components is small because one vibration generator emits the drive signal and the high-frequency signal for detection.

According to the sixth aspect of the present invention, the high-frequency signal is continuously supplied while being superimposed on the drive signal supplied to the vibration generator so as to generate vibration at the contact portion. Therefore, for example, the vibration of the contact portion is stabilized as compared with the case where the high frequency signal is intermittently supplied every predetermined time.

According to the ninth aspect of the present invention, the detected rotation position of the rotor is compared with the target rotation position, and the target setting means for stopping the power supply by the driving means when they reach substantially the same position. Is equipped with. Therefore, since the rotational position of the rotor is restricted within the range of the target rotational position, useless movement of the rotor is suppressed.

According to the tenth aspect of the invention, the fluctuating means is formed in a substantially disc shape so as to rotate integrally with the rotor. Therefore, the electrical impedance of the changing means changes according to the position (inclination) of the changing means accompanying the rotation of the rotor, and the distance between the vibration generating body (element piece) of the stator also changes, and A change appears in the intensity of the reflected vibration. Therefore, the rotational position of the rotor can be easily detected by the intensity of the reflected vibration.

According to the eleventh aspect of the invention, the fluctuating means has a notch in a part in the circumferential direction. Therefore,
The intensity of vibration reflected from the rotor to the stator corresponding to the position of the notch is extremely reduced. Therefore, the rotational position of the rotor can be easily detected by the intensity of the reflected vibration.

According to the twelfth aspect of the present invention, the rotor is a substantially spherical body, and the changing means is housed inside the rotor. Therefore, since the varying means is not exposed to the outside of the rotor, the structure is simple and the degree of freedom in design is increased.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is embodied in an animal toy robot equipped with an ultrasonic motor is shown in FIG.
~ It demonstrates according to FIG. As shown in FIG. 1, the ultrasonic motor includes a case 1, a bearing 3, a stator 4, and a rotor 5.

The case 1 is formed in a substantially cylindrical shape,
The bearing 3 is press-fitted and fixed to the opening on one side (upper part in FIG. 1). Specifically, the outer diameter of the bearing 3 is the case 1
A cylindrical support surface 3a is formed in a cylindrical shape having substantially the same inner diameter as that of the inner peripheral surface, and a spherical support surface 3a is formed below the inner peripheral surface thereof so as to be in contact with a spherical surface provided below and an annular surface. or,
On the upper side of the inner peripheral surface of the bearing 3, a tapered surface 3b is formed so that the inner diameter thereof increases toward the upper part.

The stator 4 includes the first to third elastic bodies 7 to 9
And first to third piezoelectric elements 11 to 13. The first to third elastic bodies 7 to 9 are made of a conductive metal and are made of an aluminum alloy in this embodiment. First elastic body 7
Is a substantially columnar body whose outer diameter is substantially the same as the inner diameter of the case 1, and is fixed to the opening on the other side (lower part in FIG. 1) of the case 1 to close the opening. The second elastic body 8 is a substantially columnar body, and a through hole penetrating in the axial direction is formed in the central shaft portion thereof. The third elastic body 9 is a substantially columnar body, and a through hole 9a penetrating in the axial direction is formed in the central axis portion thereof. A contact portion 9b is formed at the opening of the through hole 9a so as to come into contact with a spherical surface provided above and an annular surface.

The first to third piezoelectric elements 11 to 13 are two piezoelectric elements 11a and 11b formed in a disk shape, respectively.
13a and 13b are adhered to each other, and a through hole penetrating in the axial direction is formed in the central shaft portion thereof. These piezoelectric elements 11a, 11b to 13a, 13b are well-known electric
It is a mechanical energy conversion element that generates vibration by power feeding or generates electromotive force by vibration. As shown in FIG. 2, the electrodes 10a to 10 are provided on the entire upper surface, the entire lower surface and the entire bonding surface of the first to third piezoelectric elements 11 to 13.
h are arranged respectively.

As shown in FIG. 3, the first piezoelectric element 11
The polarization direction of the one piezoelectric element 11a constituting the above is one direction perpendicular to the plane. Also, the first piezoelectric element 1
The polarization direction of the other piezoelectric element 11b constituting 1 is opposite to that of the one piezoelectric element 11a, that is, the electrode 10b on the adhesive surface.
Is symmetrical with respect to one of the piezoelectric elements 11a.

As shown in FIG. 4, in this embodiment, the piezoelectric elements 11a and 11b have a predetermined angle (2
A plurality of (18) non-polarized regions A1 extending radially at every 0 degree are arranged, and the polarized regions divided by this form a plurality of element pieces 41 at predetermined angles. In addition, each element piece 41 of both piezoelectric elements 11a and 11b
Are arranged so that their positions in the circumferential direction coincide with each other (see FIG. 3).

The electrode 10b interposed between the piezoelectric elements 11a and 11b is composed of a plurality of electrode pieces 42 which are separated from each other in the circumferential direction corresponding to the element pieces 41. The wiring P is individually connected to. Then, for example, while the electrodes 10a and 10c are grounded, a drive signal is simultaneously supplied to each electrode piece 42 via the wiring P, so that the element pieces 4 of the piezoelectric elements 11a and 11b can be obtained.
Vibration is generated through the first piezoelectric element 11 as a whole. In this embodiment, the vibration of the first piezoelectric element 11 causes longitudinal vibration in the contact portion 9b of the third elastic body 9.

As shown in FIG. 5, the second piezoelectric element 12
The polarization direction of one of the piezoelectric elements 12a constituting the above is perpendicular to the plane, and is opposite every half of the plane. The polarization direction of the other piezoelectric element 12b constituting the second piezoelectric element 12 is opposite to that of the one piezoelectric element 12a, that is, symmetrical to the one piezoelectric element 12a about the electrode 10e on the adhesive surface. . Piezoelectric elements 12a, 12b
Also, a plurality (18) of non-polarized regions A1 (see FIG. 4) radially extending from the central portion at every predetermined angle (20 degrees) are provided, and the polarized regions divided by this are provided at predetermined angles. A plurality of element pieces 41 are formed. The element pieces 41 of the piezoelectric elements 12a and 12b are arranged so that their circumferential positions coincide with each other (see FIG. 5).

The electrode 10e interposed between the piezoelectric elements 12a and 12b is also composed of a plurality of electrode pieces 42 which are separated from each other in the circumferential direction corresponding to the element pieces 41. The wiring P is individually connected to. Then, for example, while the electrodes 10d and 10f are grounded, a driving signal is simultaneously supplied to each electrode piece 42 via the wiring P, so that the element pieces 4 of the piezoelectric elements 12a and 12b.
Vibration is generated in the second piezoelectric element 12 as a whole via the first element 1. In the present embodiment, the vibration of the second piezoelectric element 12 causes the contact portion 9b of the third elastic body 9 to generate the flexural vibration having the first direction.

Similar to the second piezoelectric element 12, the third piezoelectric element 1
The polarization direction of one of the piezoelectric elements 13a forming part 3 is perpendicular to the plane, and is opposite to each other by half of the plane. The polarization direction of the other piezoelectric element 13b constituting the third piezoelectric element 13 is opposite to that of the one piezoelectric element 13a, that is, symmetrical to the one piezoelectric element 13a about the electrode 10g on the adhesive surface. . Piezoelectric elements 13a, 13b
Also, a plurality (18) of non-polarized regions A1 (see FIG. 4) radially extending from the central portion at every predetermined angle (20 degrees) are provided, and the polarized regions divided by this are provided at predetermined angles. A plurality of element pieces 41 are formed. The element pieces 41 of the piezoelectric elements 13a and 13b are arranged in such a manner that their circumferential positions coincide with each other (see FIG. 5).

The electrode 10g interposed between the piezoelectric elements 13a and 13b is also composed of a plurality of electrode pieces 42 which are separated from each other in the circumferential direction corresponding to the element pieces 41. The wiring P is individually connected to. Then, for example, while the electrodes 10f and 10h are grounded, a driving signal is simultaneously supplied to each electrode piece 42 via the wiring P, so that the element pieces 4 of the piezoelectric elements 13a and 13b are formed.
Vibration is generated in the third piezoelectric element 13 as a whole via the first element 1. In the present embodiment, the vibration of the third piezoelectric element 13 causes the contact portion 9b of the third elastic body 9 to generate bending vibration having a second direction different from the first direction.

A first piezoelectric element 11 is arranged between the upper surface of the first elastic body 7 and the lower surface of the second elastic body 8, and the upper surface of the second elastic body 8 and the lower surface of the third elastic body 9 are arranged. The second and third piezoelectric elements 12 and 13 are arranged between them. Specifically, the first elastic body 7, the first piezoelectric element 11, the second elastic body 8, the second and third piezoelectric elements 12 and 13, and the third elastic body 9 are laminated in this order. Then, the bolt 14 erected on the first elastic body 7
Are engaged with the first piezoelectric element 11, the second elastic body 8,
The second and third piezoelectric elements 12, 13 and the third elastic body 9 are fixed on substantially concentric axes. As a result, the stator 4 is fixed to the case 1 via the first elastic body 7. still,
At this time, the second piezoelectric element 12 and the third piezoelectric element 13 are
As shown in FIG. 2, the boundary line of polarization whose polarity is reversed is
Stacked so as to be offset by 90 °. Then, the first to third piezoelectric elements 11 to 13 (piezoelectric elements 11a, 11b to 13a,
The element pieces 41 (non-polarized area A1) of 13b) are arranged in such a manner that their circumferential positions coincide with each other.

The rotor 5 is made of a rigid body such as stainless steel and has a substantially spherical spherical surface portion 5a and an output shaft 5b protruding from the spherical surface portion 5a. In the rotor 5, the output shaft 5b projects above the case 1 (bearing 3), and the bearing 3 (spherical support surface 3a) and the stator 4 (contact portion 9).
It is rotatably supported around a plurality of axes between b). At this time, in the rotor 5, the spherical surface portion 5a is pressed downward through the bearing 3 so that the spherical surface portion 5a is pressed and held by the contact portion 9b of the stator 4. The rotor 5 is allowed to rotate about a plurality of shafts until the output shaft 5b comes into contact with the tapered surface 3b of the bearing 3.

Here, as shown in FIG. 6, the rotor 5
A position detecting body 51 formed in a substantially disc shape in a plane substantially orthogonal to the axis of the output shaft 5b is housed inside the. The position detector 51 is made of a hard material such as titanium. The position detecting body 51 is formed with a cutout portion 51a cut out at the same angle (20 degrees) as the element piece 41 of the first to third piezoelectric elements 11 to 13. The position detector 51 is used to identify the high-frequency signal supplied to the stator 4 in a manner described later. As shown in FIGS. 7A and 7B, the position detection body 51 reflects the high frequency signal to the element piece 41 arranged corresponding to other than the cutout portion 51a, and the cutout portion 51a receives the high frequency signal. The high frequency signal is not reflected on the element piece 41 arranged correspondingly. The position detection body 51 binarizes the intensity of the reflected wave corresponding to the rotational position of the rotor 5 around the z-axis, which substantially coincides with the axis of the stator 4, and thereby the rotor 5 is rotated.
The rotation position around the z-axis is detected. Further, as shown in FIG. 7C, the rotor 5 rotates about the x-axis and the y-axis set in a plane orthogonal to the z-axis, and the axis (z-axis) of the stator 4 (piezoelectric element). When tilted, the distance between the element pieces 41 varies depending on the tilt angle. Then, the intensity of the reflected wave increases as the element piece 41 having a shorter distance becomes,
The longer the element piece 41, the smaller the intensity of the reflected wave. As a result, the position detector 51 detects the rotational position of the rotor 5 around the x axis and the y axis.

Any piezoelectric element 11 that is not powered
The element pieces 41 to 13 generate electromotive force according to the intensity of the reflected wave. Therefore, by detecting the electromotive force of each element piece 41 based on the intensity of the reflected wave that fluctuates in the above-described manner, the rotational position of the rotor 5 around the plurality of axes is detected.

A driven member 16 is fixed to the tip of the output shaft 5b of the rotor 5. As shown in the schematic view of FIG. 11, the driven member 16 of the present embodiment has a leg 31a and a neck 31b which are movable parts of the animal toy robot 31.
The head 31c and the tail 31d.

Next, the electrical connection and operation of this embodiment will be described. As shown in FIG. 8, this ultrasonic motor includes a position detection circuit 21 and a target value setting circuit 22.
, The actuator operating circuit 23, and the three-direction switching circuit 2
4 and. Then, the first to third piezoelectric elements 1
1 to 13 (each electrode piece 4 of electrodes 10b, 10e, 10g)
The actuator actuation circuit 23 is connected to any two of 2) via the three-way switching circuit 24, and the position detection circuit 21 is connected to the other one via the three-way switching circuit 24. ing. The electrodes 10a, 10c, 10d, 10f and 10h sandwiching the piezoelectric elements 11 to 13 are grounded (see FIGS. 3 and 5).

Any one connected to the position detection circuit 21
The two piezoelectric elements 11 to 13 detect the intensity of the reflected wave from the position detector 51. That is, the position detection circuit 21
Each element piece 41 of any one of the piezoelectric elements 11 to 13 connected to generates an electromotive force corresponding to the intensity of the reflected wave. As described above, the intensity of the reflected wave is x of the rotor 5,
It varies depending on the rotational position around the y and z axes. The position detection circuit 21 sequentially detects the electromotive force of each element piece 41 based on the intensity of the reflected wave to detect the rotational position of the rotor 5.

The position detection circuit 21 includes a target value setting circuit 22.
It is connected to the. The position detection circuit 21 detects the driven member 16 (output shaft 5) based on the detected rotational position of the rotor 5.
The tilting state of b) is calculated, and the tilting state signal S1 corresponding to the tilting state is output to the target value setting circuit 22.

The target value setting circuit 22 is connected to the actuator operating circuit 23. The target value setting circuit 22 is
Based on the tilting state signal S1, the tilting state of the driven member 16 (output shaft 5b) is brought closer to the preset (operating) tilting state of the driven member 16 (including the tilting state in the action pattern). A target value setting signal S2 including information is output to the actuator operating circuit 23.

The actuator actuating circuit 23 operates on the basis of the target value setting signal S2 to select any two of the piezoelectric elements 1.
A drive signal having, for example, a sine waveform is supplied to 1 to 13. The frequency of this drive signal is the first to third piezoelectric elements 11 to 13
It is set so that the sensitivities of the respective vibrations generated in the above are substantially equal to each other.

The three-direction switching circuit 24 is based on a switching signal from a control device (not shown) and the first to third piezoelectric elements 11 to 11.
13, position detection circuit 21, and actuator operation circuit 2
Each connection state with 3 is switched.

For example, the actuator operating circuit 23 is
The electrode 10b (electrode piece 42) on the adhesive surface of the first piezoelectric element 11
Supply a drive signal to. Similarly, the actuator operation circuit 23 supplies a drive signal to the electrode 10e (electrode piece 42) on the adhesive surface of the second piezoelectric element 12.

Then, a vertically symmetrical drive signal is supplied to the first piezoelectric element 11 with the electrode 10b on the adhesive surface common, and one piezoelectric element 11a and the other piezoelectric element 11b.
Since the polarization direction of is symmetrical with respect to the electrode 10b on the adhesive surface, a large vibration (the sum of the vibrations of the piezoelectric elements 11a and 11b) is generated in the first piezoelectric element 11. Since the polarization directions of the piezoelectric elements 11a and 11b are unidirectional on the entire plane, this vibration is a longitudinal vibration in which the upper surface and the lower surface are uniformly expanded and contracted.

Further, the electrode 10 on the adhesive surface is attached to the second piezoelectric element 12.
Since a vertically symmetrical drive signal is supplied with e being common, and the polarization directions of the one piezoelectric element 12a and the other piezoelectric element 12b are symmetrical about the electrode 10e on the adhesive surface, Large vibration is generated in the piezoelectric element 12. This vibration is a vibration in which the polarization directions of the piezoelectric elements 12a and 12b are opposite in each half of the plane, so that when one of the divided parts expands, the other contracts, and when one contracts, the other expands.

Then, in the contact portion 9b of the stator 4, a composite vibration is generated based on each vibration of the first and second piezoelectric elements 11 and 12. The rotor 5 is rotated, and the output shaft 5b and the driven member 16 (each foot 31a and neck 3) are rotated.
1b, the head 31c, the tail 31d, etc.) are tilted to a preset (operated) tilting state.

The actuator actuating circuit 23 also supplies a high frequency signal to one of the first and second piezoelectric elements 11 and 12 which supplies a drive signal. FIG. 9 is a time chart showing a drive signal including the high frequency signal. As shown in the figure, in this embodiment, a high frequency signal for a plurality of cycles is supplied instead of the drive signal in accordance with the timing of one cycle every time a predetermined number of cycles of the drive signal elapse. That is, the drive signal and the high frequency signal are selectively supplied every predetermined time. The amplitude of the high frequency signal is set to a level that ensures the amplitude of the high frequency signal (reflected wave) after the reflection from the position detection body 51.

In this embodiment, the high frequency signal is supplied to the piezoelectric element (first piezoelectric element 11 in this case) farther from the rotor 5. This is because the time difference between the high-frequency signal before reflection and the high-frequency signal (reflected wave) after reflection is made larger so that the two signals can be easily distinguished. The frequency of the high frequency signal is set to a frequency higher than the frequency of the drive signal. This is to prevent the stator 4 from vibrating due to the supply of the high frequency signal and affecting the rotation performance of the rotor 5.

On the other hand, each element piece 41 of the third piezoelectric element 13
From the position detector 51 of the electromotive force corresponding to the composite vibration due to the drive signals of the first and second piezoelectric elements 11 and 12 and the high frequency signal supplied to one of the first and second piezoelectric elements 11 and 12. Generates an electromotive force according to the intensity of the reflected wave. The rotational position of the rotor 5 is detected by detecting the electromotive force of each element piece 41 based on the intensity of the reflected wave.

Incidentally, the target value setting circuit 22 is configured so that the driven member 16 (the output shaft 5) based on the tilting state signal S1.
The driven member 1 in which the tilting state of b) is preset (operated)
6 substantially coincides with the tilted state, that is, when the detected rotational position of the rotor 5 substantially coincides with the target rotational position,
The actuator operating circuit 23 for the target value setting signal S2
Output to. Then, the supply of the drive signal via the actuator operating circuit 23 is stopped.

Even if the combination of any two of the first to third piezoelectric elements 11 to 13 related to vibration generation and the remaining one related to reflected wave detection is changed, the combined vibration at the contact portion 9b is changed. The operation mode is the same except for.

FIG. 10 shows the vibration generation and reflected wave detection (rotational position detection) of the first to third piezoelectric elements 11 to 13 with respect to the rotation of the rotor 5 around the x, y and z axes. It is a list diagram showing such a combination. In the present embodiment, the first and second
By supplying a drive signal to the piezoelectric elements 11 and 12, the rotor 5 is rotated about the y-axis, and the rotation position is set to the third piezoelectric element 1.
3 to detect. Also, the first and third piezoelectric elements 11, 1
By supplying a drive signal to 3, the rotor 5 is rotated about the x-axis, and the rotation position is detected by the second piezoelectric element 12. Further, by supplying a drive signal to the second and third piezoelectric elements 12 and 13, the rotor 5 is rotated about the z axis, and the rotation position is detected by the first piezoelectric element 11.

As described in detail above, according to this embodiment, the following effects can be obtained. (1) In the present embodiment, the rotor 5 has the position detection body 51 that changes the vibration (high frequency signal) reflected by the stator 4 according to the rotational position. Then, a high-frequency signal is supplied to one of the two piezoelectric elements 11 to 13 that generate vibration in the contact portion 9b, and the high-frequency signal reflected from the rotor 5 to the stator 4 does not generate vibration in the contact portion 9b. The rotational position of the rotor 5 was detected by detecting with any one of the piezoelectric elements 11 to 13 (element piece 41). Therefore, a special device for detecting the rotational position of the rotor 5 is not required, the structure related to the detection can be simplified, and the increase of the installation space can be suppressed. As a result, the entire device can be made compact.

Further, the frequency of the high frequency signal supplied to one of the two piezoelectric elements 11 to 13 which generate vibrations in the contact portion 9b is set sufficiently higher than the frequency of the drive signal. Also, the influence of the supply of the high frequency signal on the vibration of the contact portion 9b can be suppressed. Further, since it is a high frequency signal, it is easy to reflect from the rotor 5 to the stator 4, and the detection accuracy of the rotational position of the rotor 5 can be improved.

(2) In the present embodiment, the detected rotational position (tilt state signal S1) of the rotor 5 is compared with the target rotational position, and when the substantially same position is reached, power is supplied by the actuator operating circuit 23. A target value setting circuit 22 for stopping the operation is provided. Therefore, since the rotational position of the rotor 5 is restricted within the range of the target rotational position, useless movement of the rotor 5 can be suppressed.

(3) In the present embodiment, the position detecting body 51 is formed in a substantially disc shape so as to rotate integrally with the rotor 5. Therefore, according to the position (inclination) of the position detection body 51 due to the rotation of the rotor 5, the electrical impedance of the position detection body 51 changes and the distance from the piezoelectric element (element piece 41) of the stator 4 changes. Then, a change appears in the intensity of the high frequency signal reflected from the rotor 5 to the stator 4. Therefore, the rotational position of the rotor 5 can be easily detected from the intensity of the reflected high frequency signal.

(4) In this embodiment, the position detecting body 51 has a notch 51a in a part in the circumferential direction. Therefore, the intensity of the high frequency signal reflected from the rotor 5 to the stator 4 corresponding to the position of the cutout portion 51a is extremely reduced. Therefore, the rotational position of the rotor 5 can be easily detected from the intensity of the reflected high frequency signal.

(5) In this embodiment, the rotor 5 is a substantially spherical body, and the position detector 51 is housed inside the rotor 5. Therefore, since the position detecting body 51 is not exposed to the outside of the rotor 5, a simple structure can be obtained in which the degree of freedom in design is increased.

(6) In the present embodiment, the high frequency signal causes any one of the piezoelectric elements 11 to generate vibration in the contact portion 9b.
~ 13 only. Therefore, since there is only one high frequency signal generation source, the disturbance signal mixed in the high frequency signal reflected from the rotor 5 to the stator 4 can be reduced, and the rotational position of the rotor 5 can be determined by detecting the reflected high frequency signal. The detection accuracy can also be improved. Also, for example, a plurality (for example, 2
Since it is not necessary to synchronize each signal as in the case of supplying a high frequency signal, the structure can be simplified.

(7) In this embodiment, the high frequency signal is supplied to the piezoelectric elements 11 to 13 far from the rotor 5. Therefore, the supplied high frequency signal is transmitted from the rotor 5 to the stator 4
The time lag until it is reflected by and is detected by any one of the piezoelectric elements 11 to 13 that does not generate vibration in the contact portion 9b increases accordingly. Then, the high-frequency signal before reflection (supplied high-frequency signal) and the high-frequency signal after reflection can be easily distinguished.

(8) In the present embodiment, the high frequency signal is supplied instead of the drive signal at every predetermined time. Therefore,
Since one piezoelectric element 11 to 13 outputs a drive signal and a high frequency signal for detection, the number of parts is small.

The embodiment of the present invention is not limited to the above embodiment, but may be modified as follows. -In the above-mentioned embodiment, the position detection body 51 is the rotor 5
However, it may be provided on the driven member 16, for example. That is, the driven member 16 operates integrally with the rotor 5 and can be regarded as substantially a part of the rotor 5. Therefore, even if such a change is made, the present invention is not deviated at all. Even with such a change, the same effect as that of the above embodiment can be obtained.

In the above embodiment, the position detecting member 5
The width (20 degrees) in the circumferential direction of the notch 51a of each element element 4
Although the width is set to be equal to 1 in the circumferential direction, they may be different from each other. Even with this modification, the same effect as that of the above embodiment can be obtained.

In the above embodiment, the position detecting member 5
1 was provided, the intensity of the reflected wave was varied by the notch 51a, and the rotational position of the rotor 5 around the z axis was detected. On the other hand, as shown in FIG. 12, a position detection body 61 is provided whose longitudinal direction is arranged along the outer peripheral surface (spherical surface portion 5a) of the rotor 5 substantially orthogonal to the axis of the output shaft 5b. The position detector 61 is a vibration reflector made of a hard material such as titanium, and is located on one side in the circumferential direction to the other side (see FIG. 1).
2, the density is set to gradually decrease from the right side to the left side). Specifically, the position detector 6
1 The density is gradually lowered by increasing the number of holes provided inside. In this case, the intensity of the reflected wave from the position detector 61 increases as the density increases. That is, the same position may be detected by making the electromotive force of each element piece 41 corresponding to the density of the position detector 61 (strength of the reflected wave) correspond to the rotational position of the rotor 5 around the z axis. .
The position detector 61 may be provided over the entire circumference or a part thereof. Further, the position detecting body 61 having such a shape may be provided on the driven member 16, for example. Even with this modification, the same effect as that of the above embodiment can be obtained.

In the above embodiment, the drive signal and the high frequency signal are selectively supplied to the driven piezoelectric elements 11 to 13 every predetermined time. On the other hand, the drive signal and the high frequency signal may be always superimposed and supplied to any one of the piezoelectric elements 11 to 13 driven as shown in FIG. By making such a change, in addition to the same effects as (1) to (7) of the above-described embodiment, the high frequency signal is continuously supplied, so that the contact portion 9 is provided.
The vibration of b can be stabilized.

In the above embodiment, each of the first to third piezoelectric elements 11 to 13 and the position detecting circuit 21 and the actuator operating circuit 23 is connected by only one switching circuit (three-direction switching circuit 24). . On the other hand, the first to the third
Connection between the piezoelectric elements 11 to 13 and the position detection circuit 21, first
-Third piezoelectric elements 11-13 and actuator operating circuit 2
The connection with 3 may be performed by a switching circuit provided individually. Even with such a change, the same effect as that of the above embodiment can be obtained.

In the above embodiment, the drive signal has a sine wave shape, but it may have a pulse shape. Even with such a change, the same effect as that of the above embodiment can be obtained. -In the said embodiment, the 1st-3rd piezoelectric element 11-.
Piezoelectric elements 11a to 13a and 11b that form a set of two sheets 13
13b, it may be formed by only one piezoelectric element. Even with this modification, the same effect as that of the above embodiment can be obtained.

In the above embodiment, the first to third piezoelectric elements 11 to 13 (piezoelectric elements 11a to 13a, 11b to
Although 13b) is equally divided (18 equally) in the circumferential direction, the number is not necessarily the same, and different numbers may be equally divided. Even with such a change, the same effect as that of the above embodiment can be obtained.

In the above embodiment, the first to third piezoelectric elements 11 to 13 (piezoelectric elements 11a to 13a, 11b to
13b) was divided into 18 equal parts in the circumferential direction to form the element piece 41. On the other hand, if the piezoelectric performance or the resolution of detection is ensured, the element piece 41 is equally divided into other numbers.
May be formed. Even with such a change, the same effect as that of the above embodiment can be obtained.

In the above embodiment, the rotor 5 is made of stainless steel and the position detecting body 51 is made of titanium. However, the rotor 5 may be made of aluminum and the position detecting body 51 may be made of iron. Even with such a change, the same effect as that of the above embodiment can be obtained.

The stator 4 of the above embodiment is the rotor 5
Other configurations may be used as long as vibration in a plurality of directions can be generated at the contact portion with which the rotor 5 abuts so as to rotate about the plurality of axes.

In the above-described embodiment, the animal toy robot 31 having the ultrasonic motor is embodied, but the ultrasonic motor of each of the above-described embodiments may be replaced by another robot such as a humanoid robot,
It may be mounted on another device or the like.

Next, technical ideas other than the claims that can be understood from the above-described embodiments will be described below along with their effects. (A) In the ultrasonic motor according to any one of claims 1 to 9, the fluctuation means (61) has a higher density or hardness than the rotor (5) and has a difference in the circumferential direction. An ultrasonic motor characterized by being formed by a body. According to this structure, the reflected vibration changes according to the rotational position of the rotor. Therefore, it becomes easy to distinguish the reflected vibration according to the rotational position.

(B) In the ultrasonic motor described in (a) above, the difference in the density or hardness of the vibration reflector in the circumferential direction is set by the holes provided inside the vibration reflector. And ultrasonic motor. According to this configuration, the difference in the circumferential direction is set by an easy method without difficulty in selecting the material.

[0080]

As described above in detail, the first, second,
According to the invention described in any one of 7 and 8, in the ultrasonic motor that rotationally drives the rotor about a plurality of axes, it is possible to detect the rotational position of the rotor while suppressing an increase in the arrangement space.

According to the third or eighth aspect of the invention, since there is only one high frequency signal generation source, the disturbance signal mixed in the high frequency signal reflected from the rotor to the stator is reduced and reflected. It is also possible to improve the detection accuracy of the rotational position of the rotor by detecting the high frequency signal. Further, since it is not necessary to synchronize each signal as in the case of supplying a plurality of high frequency signals, a simple structure can be achieved.

According to the fourth aspect of the invention, it is possible to easily distinguish the high frequency signal before reflection (supplied high frequency signal) and the high frequency signal after reflection. According to the invention described in claim 5, since the amplitude is large and the frequency is high, the amplitude of the high frequency signal after reflection is large and the detection thereof can be easily performed.

According to the sixth aspect of the invention, the vibration of the contact portion can be stabilized. According to the invention of claim 9,
Since the rotational position of the rotor is restricted within the range of the target rotational position, it is possible to suppress unnecessary movement of the rotor.

According to the tenth or eleventh aspect of the invention, the rotational position of the rotor can be easily detected by the intensity of the reflected vibration. According to the twelfth aspect of the present invention, since the changing means is not exposed to the outside of the rotor, a simple structure can be provided with an increased degree of freedom in design.

[Brief description of drawings]

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

FIG. 2 is an exploded perspective view of the stator of the same embodiment.

FIG. 3 is an exploded perspective view of the stator of the same embodiment.

FIG. 4 is a plan view of the piezoelectric element according to the same embodiment.

FIG. 5 is an exploded perspective view of the stator of the same embodiment.

FIG. 6 is a partial cross-sectional view showing the rotor of the same embodiment.

FIG. 7 is a perspective view showing an operation mode of the position detection body of the embodiment.

FIG. 8 is a block diagram showing an electrical configuration of the same embodiment.

FIG. 9 is a time chart showing a drive signal and a high frequency signal.

FIG. 10 is a list diagram showing a relationship between piezoelectric elements relating to vibration generation and position detection.

FIG. 11 is a schematic diagram of an animal toy robot.

FIG. 12 is a side view showing another example of the rotor.

FIG. 13 is a time chart showing another example of a drive signal and a high frequency signal.

[Explanation of symbols]

A1 ... Non-polarized region, 4 ... Stator, 5 ... Rotor, 9b ...
Contact part, 11 ... First piezoelectric element as vibration generator, 12
... second piezoelectric element as vibration generator, 13 ... third piezoelectric element as vibration generator, 21 ... position detection circuit as detection means, 22 ... target value setting circuit as target setting means,
23 ... Actuator operating circuit as driving means, 41
... Element pieces, 51, 61 ... Position detection body as a changing means.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5H680 AA19 BB02 BB15 BC08 CC01                       DD02 DD13 DD23 DD36 DD37                       DD65 DD85 DD88 DD95 EE07                       FF04 FF26 FF36 GG01 GG27

Claims (12)

[Claims] 1. At least three vibration generators (11 to 1) that generate vibrations in different directions in a contact portion (9b).
3), and a stator (4) that combines vibrations in any two directions to generate vibrations in a plurality of directions at the contact portion (9b).
And a rotor (5) that rotates about a plurality of axes based on vibrations in a plurality of directions generated by the contact portion (9b), wherein the rotor (5) is rotated. A changing means (51, 6) for changing the vibration reflected on the stator (4) according to the position.
1), the vibration reflected from the rotor (5) to the stator (4) is detected by any one vibration generator (11 to 13) that does not generate vibration in the contact portion (9b). The ultrasonic motor is characterized in that the rotational position of the rotor (5) is detected. 2. The ultrasonic motor according to claim 1, wherein the vibration generator (1) generates vibration in the contact portion (9b).
1 to 13), and at the same time, any one of the vibration generators (which does not cause the high frequency signal reflected from the rotor (5) to the stator (4) to vibrate at the contact portion (9b) ( 11. An ultrasonic motor characterized in that the rotational position of the rotor (5) is detected by detecting the rotational position of the rotor (5). 3. The ultrasonic motor according to claim 2, wherein the high frequency signal is supplied only to any one of the vibration generators (11 to 13) that generate vibration in the contact portion (9b). Ultrasonic motor characterized by. 4. The ultrasonic motor according to claim 3, wherein the high frequency signal is supplied to the vibration generators (11 to 13) on the side far from the rotor (5). . 5. The ultrasonic motor according to any one of claims 2 to 4, wherein the high frequency signal is supplied to the vibration generator (11 to 13) so as to generate vibration in the contact portion (9b). The ultrasonic motor is characterized in that the ultrasonic motor is supplied every predetermined time in place of the drive signal. 6. The ultrasonic motor according to any one of claims 2 to 4, wherein the high frequency signal is supplied to the vibration generator (11 to 13) so as to generate vibration in the contact portion (9b). The ultrasonic motor is characterized by being continuously supplied while being superimposed on the drive signal. 7. An element piece (at a predetermined angle) in a polarization region divided by a non-polarization region (A1) which is polarized so as to generate longitudinal vibration at a contact portion (9b) and is arranged at a predetermined angle. 41) and the first piezoelectric element (11), and the non-polarized regions that are polarized by changing the polarity in the circumferential direction so as to generate bending vibration in the contact portion (9b), and are arranged at predetermined angles. A second piezoelectric element (1) in which element pieces (41) are formed at predetermined angles in the polarization region divided by (A1).
2) and polarized so that the polarities in the circumferential direction are shifted by about 90 degrees from the second piezoelectric element (12) so as to generate flexural vibrations in the contact portion (9b), and are arranged at predetermined angles. A third piezoelectric element (13) in which element pieces (41) are formed at predetermined angles in the polarized area divided by the non-polarized area (A1)
A stator (4) for generating vibrations in a plurality of directions at the contact part (9b) by combining any two vibrations of the first to third piezoelectric elements (11 to 13), A rotor (5) which rotates about a plurality of axes based on vibrations in a plurality of directions generated in the section (9b), the rotor (5) according to the rotating position, the stator (4). Fluctuating means (51, 6) for fluctuating the vibration reflected on the
Any of the first to third piezoelectric elements (11 to 13) that has 1) and that does not cause the contact part (9b) to generate vibrations reflected from the rotor (5) to the stator (4). An ultrasonic motor characterized in that the rotational position of the rotor (5) is detected by individually detecting each of the element pieces (41) formed as one. 8. The ultrasonic motor according to claim 7, wherein any two of the first to third piezoelectric elements (11 to 13) are supplied with electric power to vibrate, and a high frequency signal is supplied to one of the piezoelectric elements. Any one of the first to third piezoelectric elements (11 to 13) that is not driven by the driving means (23) for driving and the electromotive force based on the vibration reflected from the rotor (5) to the stator (4). An ultrasonic motor comprising: a detection unit (21) for individually detecting the rotational position of the rotor (5) by individually detecting the element pieces (41) formed in the above. 9. The ultrasonic motor according to claim 8, wherein the detected rotational position of the rotor (5) is compared with a target rotational position, and when the substantially same position is reached, the drive means ( 23) An ultrasonic motor comprising: a target setting means (22) for stopping power supply by means of (23). 10. The ultrasonic motor according to claim 1, wherein the changing means (51) is formed in a substantially disc shape and is provided so as to rotate integrally with the rotor (5). The ultrasonic motor is characterized by 11. The ultrasonic motor according to claim 10, wherein the fluctuating means (51) has a notch (51) at a part in the circumferential direction.
An ultrasonic motor comprising a). 12. The ultrasonic motor according to claim 10, wherein the rotor (5) is a substantially spherical body, and the changing means (51) is housed inside the rotor (5). Ultrasonic motor characterized by.