JPH1052072A - Vibration actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the speed of a vibration actuator while the actuator is stably driven by changing the relative moving speed of the actuator, by detecting the state of the stretching vibration and bending vibration of a vibrating body from the outputs of a plurality of electrodes, and changing the shape of the vibrating locus of the vibrating body which becomes circular or elliptic based on the detected results. SOLUTION: A high-frequency signal from a transmitter 21 is applied to a vibrating body 1 after the signal is amplified through frequency dividers 22 and 23 and drivers 24 and 25. Then, the voltage applied across the piezoelectric elements 1a and 1b of the vibrating body 1 is detected and the stretching vibration and bending vibration of the body 1 are detected by means of adder circuits 27 and 28. Thereafter, a microcomputer 26 discriminates the movement of the circular or elliptic vibration of the body 1 from an inputted phase difference and amplitude difference, and makes a phase shifter 31 and the driver 25 adjust the behavior of the elliptic vibration. Therefore, the movement (locus) of the actual elliptic vibration can be adjusted and, accordingly, the speed of a vibration actuator can be controlled stably.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration actuator utilizing ultrasonic vibration or the like.

[0002]

2. Description of the Related Art Conventionally, as an ultrasonic motor as a vibration actuator, for example, JP-A-61-251490, JP-A-61-35176, and JP-A-6-13.
No. 3568 is proposed. According to these publications, the proposed traveling wave type ultrasonic motor detects the vibration amplitude of the elastic body by providing a sensor phase or the like, and changes the input frequency or controls the input voltage. It was trying to obtain stable drive characteristics.

[0003]

However, due to the characteristics of the traveling wave type ultrasonic motor, the amplitude of the elliptical motion in which the vibrator is actually operating cannot be detected, but the shape of the ellipse cannot be detected. For example, if the frequency is changed, it cannot be determined whether the amplitude of the ellipse has decreased or the shape of the ellipse has changed. In addition, the input frequency is changed to control the speed of the ultrasonic motor. However, depending on the frequency, unstable factors such as sudden acceleration or stoppage may be considered.

Also, in a standing wave type ultrasonic motor, if only the amplitude of the vibration of the vibrator displaced in the vertical direction is detected, it is similarly difficult to control the speed with stable driving characteristics.

[0005]

According to a first aspect of the present invention, there is provided a vibrating body in which a plurality of electric / mechanical energy conversion elements having a plurality of electrodes formed thereon are stacked, and the vibrating body has a plurality of phases having different phases. To generate an expansion and contraction vibration and a bending vibration by applying an alternating signal of the above, and vibrating the action portion of the vibrating body so as to form a circular or elliptical locus by combining the two vibrations, and contacting the vibrating body with a contact body. A vibration actuator that relatively moves the vibrating body, detects a state of the stretching vibration and a bending vibration based on outputs from the plurality of electrodes, and generates a circular or elliptical path based on the detection result. It is characterized by a vibration actuator that changes the speed of the relative movement by changing the shape.

According to a second aspect of the present invention, a plurality of phase signals corresponding to the plurality of phase alternating signals are detected from the plurality of electrodes,
A vibration actuator that detects the states of the stretching vibration and the bending vibration by comparing the phases of the detection signals of a plurality of phases is characterized.

According to a third aspect of the present invention, a plurality of phase signals corresponding to the plurality of phase alternating signals are detected from the plurality of electrodes,
A vibration actuator that detects the states of the stretching vibration and the bending vibration by comparing the amplitudes of the detection signals of a plurality of phases is characterized.

According to a fourth aspect of the present invention, the states of the stretching vibration and the bending vibration are detected based on outputs from the plurality of electrodes,
A vibration actuator is characterized in that the phase difference between the plural-phase alternating signals is changed based on the detection result to change the shape of the trajectory of the vibration that forms the circular or elliptical trajectory.

According to a fifth aspect of the present invention, the states of the stretching vibration and the bending vibration are detected based on outputs from the plurality of electrodes,
A vibration actuator is characterized in that by changing the amplitude of the alternating signal based on the detection result, the shape of the trajectory of the vibration that forms the circular or elliptical trajectory is changed.

The invention according to claim 6 is characterized in that the plurality of electrodes is a vibration actuator which also serves as an electrode for supplying the plurality of alternating signals.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the configuration of a vibration actuator according to the present embodiment will be described.

In FIG. 1, reference numeral 1 denotes a vibrator, and a pair of plate-like piezoelectric elements 1a and 1b as electric / mechanical energy conversion elements are provided on both outer surfaces of a plate-like elastic body 1c made of phosphor bronze, brass or the like. Are pressure bonded. Also, in FIG. 2, nickel is provided on both outer surfaces (upper and lower surfaces in the figure) of the vibrating body 1.
A conductive material such as copper is deposited to form an electrode layer.
The electrode layer is divided at a position dividing the longitudinal direction of the vibrator 1 into two parts with an insulating region as a boundary, and the four electrode portions 1e to 1h
have.

The overhang portions 1c-1 and 1c are provided on the elastic body 1c.
-2, and are provided with engagement holes 1c-3 and 1c-4, respectively. The position of the overhanging portion is near the node in the vibration mode of the vibrating body 1 to avoid adverse effects on the vibration mode. Further, a total of five terminal portions 1d-1 to 5 are attached to the electrode portions 1e to 1h and the elastic body 1c by half-fitting or the like. These positions are also near the nodes in the vibration mode.

Reference numerals 2a and 2b denote a pair of drivers formed of a resin such as a phenol resin or an epoxy resin, which are attached to the position of the antinode of the vibration mode of the vibrator by bonding or the like in order to obtain a higher driving force. .

Reference numeral 3 denotes a pressure spring formed of phosphor bronze or the like.
There are overhang portions 3a and 3b, each of which has an engagement hole 3a-
1, 3b-1 are provided. Further, bent portions 3c-1 and 3c-2 are provided at both ends in the longitudinal direction of the pressure spring 3. Further, a convex portion 3d is formed in the center of the pressing spring 3 in the width direction.

Reference numeral 4 denotes a guide rail as a contact member formed of a stainless steel rope or the like.

Reference numeral 5 denotes a roller, and a support rod 5 for supporting the roller.
a is attached by a known method such as press fitting.

Reference numeral 6 denotes a plastic molded case, which is provided with engaging shafts 6a and 6b, and provided with stoppers 6c and 6d at their roots. Grooves 6g and 6h having widths slightly larger than the guide rails 4 are provided at upper ends of both ends in the longitudinal direction of the case 6. A groove 6i is provided in a part of the case 6. Further, grooves 6e and 6f are provided at both ends in the width direction of the case 6.

Reference numeral 7 denotes a plastic molded cap, which is provided with a bearing groove (not shown) for supporting the support rod 5a and a hole (not shown) to be engaged with the engaging shafts 6a and 6b. Have been. Further, projecting pieces 7a and 7b having locking claws are provided at both ends in the width direction of the cap 7.

Next, the mutual relationship between the components will be described.

The engagement shaft portions 6a, 6b provided on the case 6
The engagement holes 3a-1, 3 provided in the pressure spring 3 respectively.
b-1 is inserted. At that time, the projecting portion 3 of the pressure spring 3
a and 3b are slightly bent in the direction of the engaging shafts, so that there is no play between the engaging shafts 6a and 6b and the engaging holes 3a-1 and 3b-1. And the bent portions 3c-1, 3c
The pressure spring 6 is pushed in and stopped until -2 contacts the bottom surface of the case. The maximum amount of deflection of the pressure spring 3 is designed to bend until the overhang portions 3a, 3b abut against the stoppers 6c, 6d of the case 6.

Next, the engagement holes 1c-3, 1c-4 provided in the elastic body 1c of the vibrating body 1 are inserted into the engagement shaft portions 6a, 6b of the case 6, respectively. At that time, overhanging part 1c-1
Are slightly bent in the direction of the engaging shaft, and the engaging shaft 6
a, 6b and the engagement play between the engagement holes 1c-3, 1c-4 are eliminated. Then, the piezoelectric element 1b of the vibrating body 1 is
The vibrating body 1 is pushed until it comes into contact with the convex portion 3d.

Both ends of a support rod 5a attached to the roller 5 by press-fitting or the like are supported by bearings (not shown) provided on the cap 7.

A case 6 on which the pressure spring 3 and the vibrating body 1 are mounted, and a cap 7 on which the roller 5 is mounted are mounted so that the guide rail 4 is sandwiched between the surface of the roller 5 and the surfaces of the drivers 2a and 2b. Can be At this time, the protruding pieces 7a and 7b having the locking claws provided on the cap 7 are guided by the grooves 6e and 6f of the case 6, and are attached by snap fitting. At this time, the engaging shaft portions 6a and 6b of the case 6 and the holes (not shown) provided in the cap 7 are engaged with each other, and the cap 7 is positioned with respect to the case 6. The movement of the guide rail 4 in the width direction is restricted by the grooves 6g and 6h of the case 6.

The electrode portions 1e to 1h and the terminal portions 1d-1 to 5 provided on the elastic body 1c are soldered to lead wires or a flexible printed circuit board.
Power supply and sensing can be performed by being drawn out of the case 6 and connecting a lead wire or a flexible printed circuit board to an external drive circuit.

The driving principle of the vibration actuator according to the present embodiment will be described.

FIG. 3 is a diagram showing the piezoelectric effect of the piezoelectric element. In the figure, reference numeral 10 denotes a piezoelectric element, which is subjected to a polarization process from above to below in the figure (in the direction of the arrow in the figure). Further, electrode portions 10a and 10b are formed on both surfaces of the piezoelectric element by a vapor deposition process.

FIG. 3A is a diagram showing a state where a positive potential is applied to the electrode portion 10a and a negative potential is applied to the electrode portion 10b. In this case, the piezoelectric element includes the electrode portion 10a from the electrode portion 1a.
Since an electric field is applied in the direction of 0b, that is, in the forward direction with respect to the polarization direction, the piezoelectric element expands in a direction perpendicular to the polarization direction according to the magnitude of the electric field.

FIG. 3B is a diagram showing a state in which a negative potential is applied to the electrode portion 10a and a positive potential is applied to the electrode portion 10b. In this case, the piezoelectric element includes the electrode portion 10b and the electrode portion 1
Since an electric field is applied in the direction of 0a, that is, in the direction opposite to the polarization direction, the piezoelectric element contracts in a direction perpendicular to the polarization direction according to the magnitude of the electric field.

FIG. 3C is a diagram showing a state where the piezoelectric element is extended by an external force in a direction perpendicular to the polarization direction. In this case, a positive potential is applied to the electrode portion 10a,
A negative potential is generated at b, and a potential difference corresponding to the amount of elongation is generated.

FIG. 3D is a view showing a state where the piezoelectric element is contracted by an external force in a direction perpendicular to the polarization direction. In this case, a negative potential is applied to the electrode portion 10a, and the electrode portion 10b
, A positive potential is generated, and a potential difference corresponding to the amount of shrinkage is generated.

The piezoelectric vibrator of the vibration actuator according to the present embodiment is intended to excite a standing wave so as to generate a circular or elliptical motion in the driver by utilizing these piezoelectric phenomena.

FIG. 4 is a side view of the vibrating body of the vibration actuator according to the present embodiment. The piezoelectric element 1a is subjected to polarization processing from the bottom of the figure to the top, and the piezoelectric element 1b is subjected to polarization processing from the top to the bottom of the figure. The elastic body 1c is connected to the ground. In the vibrating body 1 configured as described above, the electrode portions 1e and 1h have the same phase as shown in FIG.
Applying a frequency voltage V _A of the same amplitude, applying the same phase, the same amplitude-frequency voltage V _B to the electrode portions 1f and 1 g (However, the electrode unit 1
e and the frequency voltage to 1h have different phases), the vibrating body develops various behaviors due to the piezoelectric effect. For example, the behavior of the vibrating body at time t ₁ in FIG.
Since the same value + voltage is applied to １1h, FIG.
Shrinkage as shown in (c) occurs. Behavior of the vibrator at the time t ₂ in FIG. 5, the electrode portion 1e, the 1h is applied a voltage of +, the electrode unit 1f, to 1 g - and the electrode portion 1e is voltage, and the voltage applied to 1h Since a voltage having the same absolute value is applied, it bends as shown in FIG.

The behavior of the vibrating body at time t ₃ in FIG.
Since a negative voltage having the same value is applied to the electrode portions 1e to 1h, elongation occurs as shown in FIG. The behavior of the vibrating body at time t ₄ in FIG.
6B, a voltage of + is applied to the electrodes 1f and 1g and a voltage having the same absolute value as the voltage applied to the electrodes 1e and 1h is applied, as shown in FIG. 6B. To bend.

From the above, looking at the behavior over a continuous time, the vibrating body has a stretching motion (longitudinal vibration) and a bending motion (lateral vibration).
Indicate the synthesized behavior, and the drivers 2a and 2b draw a circular or elliptical orbit. The rotation directions of the circular or elliptical orbits of the drivers 2a and 2b coincide with each other. The rotational direction of the reversing the phase of the frequency voltage V _A and V _B circular or elliptical orbit becomes the direction opposite to the direction.

When a sliding member such as a guide rail is pressed against the drivers 2a and 2b that perform circular or elliptical motion as described above, a driving force is generated, and the sliding member such as the guide rail and the driver are relatively moved. It becomes movable. That is, if one is fixed, the other moves, and conversely, if the other is fixed, one moves.

A method of detecting the horizontal vibration and the vertical vibration of the vibration actuator according to the present embodiment will be described.

As described above, when the piezoelectric element is deformed by the piezoelectric effect, a voltage corresponding to the amount of the deformation is generated.

The magnitude of the transverse vibration (bending vibration) at any time is determined by the amount of expansion (or contraction) of the piezoelectric elements 1a and 1b due to the voltage applied to the electrodes 1e and 1h at any time.
And the amount of contraction (or elongation) of the piezoelectric element due to the voltage applied to the electrode portions 1f and 1g. That can be expressed by the difference between the output voltage S _B from the output voltage S _A and the driving electrode portion 1g from the driving electrode portion 1h.

The magnitude of the longitudinal vibration at any time is determined by the amount of expansion (or contraction) of the piezoelectric element due to the voltage applied to the electrodes 1e and 1h at any time, and the amount of the electrodes 1f and 1g.
It is determined by the amount of expansion (or contraction) of the piezoelectric element due to the voltage applied to the piezoelectric element. That can be expressed by the sum of the output voltage S _B from the output voltage S _A and the driving electrode portion 1g from the driving electrode portion 1h.

[0041] Figure 7, the electrode portions 1e of the vibration member 1, a frequency voltage V _A shown in FIG. 5 is applied to 1h, the electrode portions 1f, when applying a frequency voltage V _B shown in FIG. 5 to 1g, drive shows the voltage waveform of the S _a + S _B indicating the longitudinal vibration and S _a -S _B representing the output voltage S _a and lateral vibration from the output voltage S _B and the driving electrode portion 1h of the use electrode portion 1g.

When S _A + S _B is set on the horizontal axis and S _A -S _B is set on the vertical axis, a curve is drawn along time, as shown in FIG.
This curve is a correct representation of the driver's circular or elliptical trajectory.

As described above, by detecting the output voltage S _A from the driving electrode portion 1h and the output voltage S _B from the driving electrode portion 1g, the behavior of the lateral vibration and the longitudinal vibration can be determined, and the driver or It can be seen that an elliptical orbit can be represented.

By the way, the tangential velocity of the wave front of the circular or elliptical motion differs depending on the shape of the circular or elliptical orbit. For example, the tangential velocity at point P ₂ of the elliptical orbit of FIG. 9B is slower than the tangential velocity at point P ₁ of the circular orbit of FIG. 9A, and the elliptical orbit of FIG. the tangential velocity is faster in the P ₃ points. Therefore, if the circular or elliptical trajectory in FIG. 9 is the movement of the driver, by changing the shape of the elliptical trajectory, the relative speed with respect to a sliding member such as a guide rail can be changed. is there.

[0045] Therefore, the electrode portion 1e, and the applied frequency voltage V _A to 1h, the electrode portions 1f, by changing the phase difference and / or amplitude ratio of the applied frequency voltage V _B to 1g, of the elliptical orbit of the drivers We considered changing the shape and changing the relative speed with the sliding member.

First, a circular or elliptical orbit when the phase difference is changed while the amplitudes of the applied frequency voltages V _A and V _B are constant (the amplitudes of the output voltages S _A and S _B are also constant in principle) is drawn. Then, the result is as shown in FIGS.

In FIG. 10, the phase difference between the applied frequency voltages V _A and V _B is α (the phase difference between the output voltages S _A and S _B is also 0 in principle).
° <α <180 °), the applied frequency voltage V _A in FIG.
And the phase difference between V _B and V _B (the phase difference between the output voltages S _A and S _B is also in principle 0 ° <β <180 °), and the phase difference between the applied frequency voltages V _A and V _B in FIG. Assuming that the phase difference between the output voltages S _A and S _B is also 0 ° <γ <180 ° in principle), β>
By setting it to α, the shape of the elliptical orbit becomes longer than that of the phase difference α. Further, by setting γ <α, the shape of the elliptical orbit becomes longer in comparison with the case of the phase difference α.

From the above, the applied frequency voltages V _A and V _B
When the phase difference is changed while the amplitude of the elliptical orbit is kept constant, the shape of the elliptical orbit changes, and the tangential velocity of the wave front of the elliptical orbit changes. In other words, by changing the tangential velocity of the elliptical orbit of the driver,
The relative speed with respect to a sliding member such as a guide rail can be arbitrarily changed.

Next, the phase difference between the applied frequency voltage V _A and V _B is set to 90 °, varying the amplitude ratio of the applied frequency voltage V _A and V _B, 13, 14, as shown in FIG. 15 become.

The amplitudes of the output voltages S _A and S _B of the sensor electrode portion according to the amplitude of the applied frequency voltage are represented by a ₁ and b ₁ in FIG. 13, a ₂ and b ₂ in FIG. 14, and a ₂ and b ₂ in FIG. _3, and b _3.

| A ₁ | = | a ₂ | = | a ₃ | = | b ₁ |
> | B ₂ |> | b ₃ | The amplitude of the applied frequency voltage is adjusted so that each elliptical orbit is compared. When compared with the case of b ₁ , the shape of the elliptical orbit at b ₂ is It becomes slightly elongated. Also, the more elongated shape in the case of b _3.

From the above, the applied frequency voltages V _A and V _B
Of the phase difference is set to 90 °, varying the amplitude ratio of the applied frequency voltage V _A and V _B, changes the shape of the elliptical orbit, the tangential velocity of the wave front of the elliptical orbit is changed. That is, the tangential speed of the elliptical orbit of the driver can be changed, and the relative speed with respect to the sliding member such as the guide rail can be arbitrarily changed.

Next, the control will be described.

FIG. 16 is a block diagram showing an embodiment of the present invention.

The high frequency signal higher than the driving frequency output from the oscillator 21 is divided by the frequency dividers 22 and 23 to a predetermined frequency, converted into a driving frequency and output to the drivers 24 and 25. Drivers 24, 25
Amplifies the signal obtained from the frequency divider and applies it to the vibrator 1. When a signal is applied to the vibrating body 1, the coil 24
a, the coil 25b and the piezoelectric elements 1a and 1b resonate,
A voltage higher than the input voltage of the drivers 24 and 25 is applied to the piezoelectric elements 1a and 1b. The voltage applied to the piezoelectric elements 1a and 1b at this time is detected, A + B is performed by the addition circuit 27 to detect longitudinal vibration, and the subtraction circuit 28 performs AB to detect bending vibration. The detected longitudinal vibration and bending vibration are sent to the phase comparator 29 and the amplitude comparator 30, and the results of the comparison are compared with each other by the microcomputer 2.
6 is output. The microcomputer 26 determines the behavior of the circular or elliptical vibration from the input phase difference and amplitude difference, and outputs a signal to the phase shifter 31 and the driver 25 to adjust the behavior of the elliptical vibration, respectively.

For example, as shown in FIG. 17A, the amplitude comparator 30 performs half-wave rectification on each of the signals A + B and AB represented by a sine wave function, converts them into DC components, and converts them into amplitude values. After the conversion, the microcomputer 26 performs A / D conversion and compares the signals.

Therefore, the phase difference between the input signals A and B is changed by the phase shifter 31 based on the obtained amplitude ratio. For example, FIG.
8, the clock from the oscillator 21 is supplied to the counter 22a,
Before inputting to 23a, the initial value of the counter B is set and the phase difference with the counter A is set. Thereafter, the clock is input to the counters 22a and 23a, and is compared with a predetermined comparison value. As a result, the phase always shifts by the initial value. Comparators 22b and 23
b is divided by the frequency dividers 22c and 23c and converted into a rectangular wave having a duty ratio of 50%.
25. Thereby, the phase difference of the drive signal can be arbitrarily changed.

As shown in FIG. 17B, the phase comparator 29 compares A + B and AB with the hysteresis comparators 29a and 29a.
At 29b, the value is compared with a reference value and converted into a rectangular wave. The converted rectangular wave passes through the EXOR 29c and turns ON for the time of the phase difference
And a phase difference can be determined based on the number of reference clocks in the microcomputer during that time.

Further, based on the obtained phase difference, the microcomputer 26
Adjusts the behavior of the elliptical vibration by changing the voltage applied to the driver 25, that is, changing the amplitude ratio by changing one of the amplitudes. For example, as shown in FIG. 19, the power supply of the driver 25 is determined by the DC / DC converter 25a. In this case, the voltage output by the comparator 26b can be controlled by the voltage output by the microcomputer in order to control the voltage output by the DC / DC converter 25a.

In the above-described embodiment, both the change of the phase difference and the change of the amplitude ratio can be realized. Of course, the behavior (trajectory) of the elliptical vibration is adjusted by only one of them. Is what you can do.

According to the above description, the actual behavior (trajectory) of the elliptical vibration can be adjusted, and the speed control of the vibration actuator can be stably performed.

[0062]

According to the first aspect of the present invention, the state of expansion and contraction vibration and bending vibration of a vibrating body which supplies an alternating signal of a plurality of phases and vibrates the action portion in a circular or elliptical locus is detected. Since the speed of the relative movement is changed by changing the trajectory shape of the vibration that forms the circular or elliptical trajectory based on the detection result, it is possible to perform speed control with stable driving characteristics. A vibration actuator can be provided.

According to a second aspect of the present invention, the state of the stretching vibration and the state of the bending vibration are detected by detecting signals of a plurality of phases corresponding to the alternating signals of the plurality of phases and comparing the phases of the detection signals of the plurality of phases. Therefore, it is possible to provide a vibration actuator capable of accurately determining the shape of a circular or elliptical locus.

According to a third aspect of the present invention, the state of the stretching vibration and the state of the bending vibration are detected by detecting signals of a plurality of phases corresponding to the alternating signals of the plurality of phases and comparing the amplitudes of the detection signals of the plurality of phases. Therefore, it is possible to provide a vibration actuator capable of accurately determining the shape of a circular or elliptical locus.

According to a fourth aspect of the present invention, the circular or elliptical trajectory is obtained by detecting the states of the stretching vibration and the bending vibration and changing the phase difference between the plurality of alternating signals based on the detection result. Since the shape of the trajectory of the vibration is changed, it is possible to provide a vibration actuator capable of performing reliable and stable speed control.

According to a fifth aspect of the present invention, the state of the stretching vibration and the bending vibration is detected, and the amplitude of the alternating signal is changed based on the detection result, whereby the circular or elliptical trajectory is formed. Is changed, it is possible to provide a vibration actuator capable of performing reliable and stable speed control.

According to the sixth aspect of the present invention, since the electrode for supplying the alternating signal of the plurality of phases is also used as the electrode for detection, it is possible to provide a compact and low-cost vibration actuator.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a vibration actuator according to the present embodiment.

FIG. 2 is a view showing the structure of the vibrating body of FIG. 1;

FIG. 3 is a diagram showing the principle of vibration.

FIG. 4 is a diagram showing a polarization state of the vibrating body of FIG. 1;

FIG. 5 is a diagram showing an example of an alternating signal supplied to a vibrating body.

FIG. 6 is a diagram illustrating a vibration state of a vibrating body at each time t in FIG. 5;

FIG. 7 is a diagram showing an example of an alternating signal supplied to a vibrating body.

FIG. 8 is a diagram showing a relationship between a phase difference and an amplitude ratio.

FIG. 9 is a diagram showing a circular or elliptical locus.

FIG. 10 is a diagram showing a vibration trajectory by setting a phase difference and an amplitude ratio.

FIG. 11 is a diagram illustrating a vibration trajectory by setting a phase difference and an amplitude ratio.

FIG. 12 is a diagram illustrating a vibration trajectory by setting a phase difference and an amplitude ratio.

FIG. 13 is a diagram illustrating a vibration trajectory by setting a phase difference and an amplitude ratio.

FIG. 14 is a diagram showing a vibration trajectory by setting a phase difference and an amplitude ratio.

FIG. 15 is a diagram illustrating a vibration trajectory by setting a phase difference and an amplitude ratio.

FIG. 16 is a block diagram illustrating a control circuit of this embodiment.

FIG. 17 is a circuit diagram showing a part of the control circuit in FIG. 16;

FIG. 18 is a circuit diagram and a time chart showing a part of the control circuit in FIG. 16;

FIG. 19 is a circuit diagram showing a part of the control circuit in FIG. 16;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vibration body 1e, 1f, 1g, 1h Electrode part 4 Guide rail as a contact body

Claims (6)

[Claims] 1. A vibrating body in which a plurality of electric / mechanical energy conversion elements on which a plurality of electrodes are formed are stacked, and an alternating signal of a plurality of phases having different phases is applied to the vibrating body to cause expansion and contraction vibration and bending. A vibration actuator that generates vibration, vibrates the acting portion of the vibrating body so as to form a circular or elliptical locus by combining the two vibrations, and relatively moves the contacting body that comes into contact with the vibrating body and the vibrating body. In, detecting the state of the stretching vibration and the bending vibration by the output from the plurality of electrodes, and by changing the trajectory shape of the vibration that becomes the circular or elliptical trajectory based on the detection result, the relative movement of the A vibration actuator characterized by changing a speed. 2. The state of the stretching vibration and the state of the bending vibration are detected by detecting signals of a plurality of phases corresponding to the alternating signals of the plurality of phases from the plurality of electrodes and comparing the phases of the detection signals of the plurality of phases. The vibration actuator according to claim 1, wherein: 3. The state of the stretching vibration and the bending vibration is detected by detecting signals of a plurality of phases corresponding to the alternating signals of the plurality of phases from the plurality of electrodes and comparing the amplitudes of the detection signals of the plurality of phases. The vibration actuator according to claim 1, wherein: 4. The circular or elliptical shape by detecting states of the stretching vibration and the bending vibration based on outputs from the plurality of electrodes, and changing a phase difference between the alternating signals of the plurality of phases based on a detection result. The vibration actuator according to claim 1 or 3, wherein the shape of the trajectory of the vibration serving as the trajectory of (i) is changed. 5. The circular or elliptical trajectory is detected by detecting the states of the stretching vibration and the bending vibration based on the outputs from the plurality of electrodes, and changing the amplitude of the alternating signal based on the detection result. 3. The vibration actuator according to claim 1, wherein a shape of a vibration trajectory is changed. 6. The system according to claim 1, wherein the plurality of electrodes also serve as electrodes for supplying the alternating signals of the plurality of phases.
6. The vibration actuator according to any one of items 5 to 5.