JP2002010656A - Vibration actuator - Google Patents

Abstract

(57) [Summary] [Problem] When an ultrasonic actuator is driven by self-excited driving, it is difficult to change the direction of linear movement and further control the speed during movement. SOLUTION: A vibrator 21 having two vibration detection areas 25p and 25p 'while exciting a longitudinal vibration vibrating in a driving direction and a bending vibration vibrating in a direction orthogonal to the vibration direction of the longitudinal vibration; By performing arithmetic processing on the two signals extracted from the detection areas 25p and 25p ', respectively, a signal relating to the longitudinal vibration is generated, and the generated signal is fed back to the input unit, thereby obtaining a value substantially equal to the resonance frequency of the longitudinal vibration. Actuator 30 having a driving device 30 for inputting a driving signal having a frequency of
0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a vibration actuator. More specifically, the present invention relates to a vibration actuator driven by so-called self-excited drive.

[0002]

FIG. 6 is a perspective view showing a conventional ultrasonic actuator 1 having a vibrator 2. As shown in FIG. FIG. 7 is an explanatory diagram showing an example of two vibration waveforms generated in the vibrator 2.

As shown in FIGS. 6 and 7, the vibrator 2 comprises:
It has an elastic body 3 and an electromechanical transducer 4 for converting electric energy into mechanical energy (hereinafter, described by taking a “piezoelectric body” as an example). The elastic body 3 is formed in a rectangular flat plate shape from a metal material having a large resonance sharpness. In the elastic body 3,
The dimensions of each part are set such that the natural frequencies of the generated longitudinal vibration L1 and bending vibration B4 substantially match. The piezoelectric body 4 is attached and attached to one plane of the elastic body 3.
The piezoelectric body 4 has four areas, namely, input sections 4a and 4b to which two-phase drive voltages of A-phase and B-phase are applied, a detection section 4p for monitoring the vibration state of the vibrator 2, and a ground section 4g. Are continuously formed. For example, silver electrodes 5a, 5b, 5p, 5
g are glued apart from each other. Furthermore, a other plane of the elastic body 3, with respect to the longitudinal direction of the vibrator 2, on the outside of the loop position l _1, l ₄ of the four loop position l ₁ to l ₄ bending vibration B4 generated , Two driving force take-out portions 3
a, 3b are formed. Sliding members 7a and 7b mainly composed of a resin material such as a polymer material, a metal material, or the like are attached to the bottom surfaces of the driving force extracting portions 3a and 3b, for example, with an epoxy resin adhesive. Through these sliding members 7a and 7b, the plate-shaped relative motion member 6 is brought into pressure contact with an appropriate pressing force.

In this state, the elastic members 3 are attached to the input portions 4a and 4b.
, And high-frequency driving voltages V _A and V _B whose phases are substantially equal to the natural frequencies of the longitudinal vibration L1 and the bending vibration B4 and whose phases are shifted by (π / 2), respectively. Then, as shown in FIG. 7, the elastic body 3 is excited by a first-order longitudinal vibration L1 vibrating in the longitudinal direction of the vibrator 2 and a fourth-order bending vibration B4 vibrating in the thickness direction of the vibrator 2. Is done. The longitudinal vibration L1 and the bending vibration B4 generated in the elastic body 3 are synthesized,
An elliptical motion that periodically displaces in an elliptical shape is generated on the bottom surface of each of the driving force extracting portions 3a and 3b. As a result, the vibrator 2 performs a linear relative motion in the longitudinal direction of the vibrator 2 between the vibrator 2 and the relative motion member 6 that is brought into pressure contact via the sliding members 7a and 7b.

Incidentally, as a general driving method of such an ultrasonic actuator, so-called separately-excited driving is known. The other excitation drive uses a power supply (for example, an external oscillator and a drive amplifier) that supplies a drive signal having a drive frequency capable of driving the ultrasonic actuator, and drives the vibrator near its mechanical resonance frequency. This is a driving method that forcibly vibrates at a frequency, and is excellent in various controllability. However, in order to perform the other excitation driving, an external driving oscillator and a driving amplifier are required, and since the driving frequency of the ultrasonic actuator is sensitive to temperature, it is necessary to correct the driving frequency by appropriate means. is there. For this reason, the cost required for the drive device increases in the separate excitation drive.

For this reason, in recent years, it has been studied to drive an ultrasonic actuator by so-called self-excited drive. In this self-excited drive, a drive operation is performed by forming a closed loop between the drive amplifier and the ultrasonic actuator and applying positive feedback using the resonance characteristics of the drive amplifier and the ultrasonic actuator to function as an oscillator. For example, the resonance characteristics of a vibration feedback type or an ultrasonic actuator in which a vibration detection electrode is provided on a vibrator and a positive feedback loop is formed using a signal obtained from the vibration detection electrode to operate. Is used as an inductive or capacitive element, for example, a positive feedback is applied as a Hartley type or Colpitts type oscillator. This self-excited drive uses the vibrator of the ultrasonic actuator itself as a part of the oscillation element, so that the temperature tracking performance is improved, and the ultrasonic actuator is less affected by individual differences and the environmental temperature. It has various features such as an increase in the possibility of reducing the cost.

FIG. 8 is a block diagram showing a configuration example of a conventional self-excited drive circuit 8 constituting a vibration feedback oscillation circuit. In the figure, reference numeral 9 indicates a phase correction circuit, reference numeral 10 indicates a harmonic (spurious) suppression filter, and reference numeral 11 indicates a driving amplifier.

[0008] Ultrasonic actuator 1 to drive amplifier 1
G1 and G are the voltage ratios (amplification factors) between the input and output of each element
Assuming that the phase difference between the input and output of each element is Θ1, Θ2, Θ3, and Θ4, as well as G3 and G4, the condition for oscillating this closed loop is defined by the following equations and equations as is well known. Is done.

G 1 ２G 2 ＧG 3 ＧG 4 ≧ 1 ・ ・ ・ 1 + Θ2 + Θ3 + ° 4 = 0 ° ・ ・ ・ Therefore, the phase difference Θ2 between the input and output of the phase correction circuit 9 is appropriately adjusted. By setting the phase difference of this closed loop to zero, the self-excited drive of the ultrasonic actuator 1 is performed.

[0010]

However, when the ultrasonic actuator 1 is driven by self-excitation in this manner, there are the following problems.

(I) When the roles of the driving force by the A-phase drive signal and the B-phase drive signal are reversed in order to change the direction of the linear movement of the ultrasonic actuator 1, the operating characteristics are accompanied by this reverse rotation. Fluctuates, and the characteristics of the self-excited operation fluctuate due to the direction change.

(Ii) In the ultrasonic actuator 1, various other various vibrations occur in addition to the first-order longitudinal vibration L1 and the fourth-order bending vibration B4. For this reason, in order to prevent the ultrasonic actuator 1 from oscillating and vibrating due to these other vibrations, a phase correction circuit 9 and a harmonic (spurious) suppression filter 10 are provided. From the desired frequency characteristics,
The characteristics vary depending on the frequency characteristics of the phase correction circuit 9 and the harmonic suppression filter 10. That is, the entire driving device 8 includes the phase correction circuit 9 and the harmonic suppression filter 1.
Since the temperature characteristics of 0 or the like are affected, the tracking characteristics of the temperature change and the like, which are characteristics of the self-excited drive, are reduced, and the accuracy of the speed control is reduced.

As described above, if the ultrasonic actuator is driven by self-excited driving, the temperature tracking property is improved, the influence of the individual difference of the ultrasonic actuator and the influence of the environmental temperature are eliminated, and the cost of the entire driving device is expected to be reduced. Nevertheless, there has been a problem that it is difficult to change the linear movement direction, which is one of the basic controls of the ultrasonic actuator, and to perform speed control during movement.

In view of the above-mentioned problems of the prior art, an object of the present invention is to change the direction of linear movement, which is one of the basic controls by self-excited driving, and to control the speed during movement. And a vibration actuator such as an ultrasonic actuator.

[0015]

SUMMARY OF THE INVENTION According to the present invention, when self-excited driving is performed, the position of a vibration detecting electrode to be mounted on a vibrator constituting a vibration actuator is optimized, and the vibration detecting electrode is used. By performing self-excited drive using signals obtained from the electrodes, it is possible to reliably change the direction of linear movement and further control speed during movement, thereby improving temperature tracking and improving ultrasonic This is based on a new and important finding that it is possible to eliminate the effects of individual differences of actuators and environmental temperature and to reduce the cost of the entire driving device.

According to the first aspect of the present invention, the first vibration vibrating in the driving direction and the second vibration vibrating at substantially the same frequency as the first vibration in a direction intersecting with the vibration direction of the first vibration. Is excited, and a vibrator having at least two vibration detection regions provided at positions substantially symmetrical with respect to the node position of the first vibration, and two signals respectively taken out from the at least two vibration detection regions By performing a calculation process, a signal related to the first vibration is generated, and the generated signal related to the first vibration is fed back to the input unit.
A driving device for inputting a driving signal having a frequency substantially equal to the resonance frequency of the first vibration to the vibrator.

According to a second aspect of the present invention, in the vibration actuator according to the first aspect, the two vibration detection areas are:
It is provided at a position including a node position of the second vibration.

According to a third aspect of the present invention, there is provided the first or second aspect.
, The two vibration detection areas are provided at positions different from the position including the node position of the first vibration.

According to a fourth aspect of the present invention, there is provided the first to third aspects.
In the vibration actuator described in any one of the above, the arithmetic processing is an addition processing. According to a fifth aspect of the present invention, in the vibration actuator according to any one of the first to fourth aspects,
It is characterized in that the first vibration is a longitudinal vibration and the second vibration is a bending vibration.

According to a sixth aspect of the present invention, in the vibration actuator according to any one of the first to fifth aspects, the vibrator has a rectangular flat plate-like outer shape.
The two vibration detection areas are provided at symmetrical positions with respect to the center of the plane of the vibrator.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) Hereinafter, embodiments of a vibration actuator according to the present invention will be described in detail with reference to the accompanying drawings. In the following description of each embodiment, a case where the vibration actuator is an ultrasonic actuator using an ultrasonic vibration region will be described as an example.

FIG. 1 is a perspective view showing the configuration of an ultrasonic actuator 20 according to the present embodiment. FIG. 2 is an explanatory diagram showing an example of a vibration waveform generated in the vibrator 21 of the ultrasonic actuator 20.

As shown in FIGS. 1 and 2, the ultrasonic actuator 20 of the present embodiment comprises a vibrator 21 and
Relative motion member 26 that generates relative motion with vibrator 21
And a driving device 30. Hereinafter, these components will be sequentially described.

[Vibrator 21] The vibrator 21 is an elastic body 22.
And a piezoelectric body 23 mounted on one plane of the elastic body 22.

The elastic body 22 is made of SUS30 in this embodiment.
4 form a rectangular flat plate. The dimensions of each part of the elastic body 22 are set such that the natural frequencies of the generated primary longitudinal vibration L1 and the quaternary bending vibration B4 substantially coincide with each other.
Is set. The elastic body 22 may be formed of a metal material having a large resonance sharpness, such as ordinary steel, phosphor bronze, or Elinvar material, other than stainless steel.

On one flat surface of the elastic body 22, a piezoelectric body 23 to be described later is mounted, for example, by bonding. Further, two grooves in the width direction of the elastic body 22 are provided on the other plane of the elastic body 22 at a predetermined distance from each other in the relative movement direction (the left-right direction in FIG. 2). A sliding member having a rectangular cross-sectional shape is fitted into these grooves, adhered with an epoxy-based adhesive, and mounted in a protruding manner.

The sliding member is used as the driving force take-out portion 22.
a and 22b. Therefore, the elastic body 22
Are driving force take-out portions 22a, 22b made of these sliding members.
And the relative motion member 26 is contacted.

As shown in FIG. 2, the driving force take-out portions 22a,
22b is provided at a position that matches antinode positions l _1, l ₄ located outside of the four loop position l ₁ to l ₄ fourth-order bending vibration B4 generated in the elastic member 22. In addition, the driving force extracting portions 22a and 22b are connected to the antinode position l ₁ of the bending vibration B4,
need not be in a position to exactly match the l _4, may be in the vicinity of the antinode position.

In the present embodiment, the piezoelectric body 23 is composed of a thin plate-like piezoelectric element made of PZT (lead zirconate titanate). The input regions 23 a and 23 c to which the A-phase drive signal is input and the B-phase drive signal whose phase is shifted by (π / 2) from the A-phase drive signal are input to the piezoelectric body 23. Regions 23b and 23d are formed. Each input region 23a~23d, as shown in FIG. 2, is formed into four regions partitioned by five nodal position n ₁ ~n ₅ bending vibration B4 generated in the elastic member 22. That is, each input region 23a~23d be deformed by input of the driving signal are both, because does not cross the nodal position n ₁ ~n ₅ is a fixed point, the deformation of the input region 23a~23d knots position n ₁ ~ n ₅
It is not suppressed by. Therefore, the electric energy input to each of the input areas 23a to 23d is transformed with maximum efficiency into the deformation of the elastic body 22, that is, converted into mechanical energy. In the vibrator 21 of the present embodiment, the relative motion member 26 can be driven more efficiently by inputting a drive signal closer to the resonance frequency of the longitudinal vibration L1 than the resonance frequency of the bending vibration B4.

Further, at the nodal positions n ₂ and n ₄ of the bending vibration B4, detection regions 23p and 23p 'for outputting electric energy by the longitudinal vibration L1 generated by the vibrator 21 are provided in a semicircular shape. Pickup signals are output from the detection areas 23p and 23p '. Based on the pickup signal, the vibration state of the longitudinal vibration L1 generated by the vibrator 21 is detected.

Each of the input areas 23a to 23d and each of the detection areas 2
3p and 23p 'mean that each surface is a silver electrode 25a.
To 25d, 25p, and 25p ', and the silver electrodes 25a to 25d, 25p, and 25p' are connected to a driving device 30 described later by lead wires (not shown). As a result, the input regions 23a to 23a
A drive signal is input independently to each of the detection areas 23d.
A detection signal can be output independently of 3p and 23p 'and input to the driving device 30.

In this embodiment, the vibrator 21 is formed so as to be point-symmetric with respect to the center O of the plane of the vibrator 21. As a result, the driving force extracting portions 22a, 22b
Can be made substantially the same shape, and a drive difference (left-right difference) due to reversal of the relative motion direction hardly occurs.

Further, since the detection areas 23p and 23p 'are arranged symmetrically with respect to the node position of the longitudinal vibration L1 of the vibrator 21,. A pickup signal having substantially the same frequency component is obtained from both detection areas 23p and 23p '. By using this signal for the driving device 30 described later, the vibrator 21 can be favorably excited.

In this embodiment, the vibrator 11 is configured as described above. [Relative Motion Member 26] As shown in FIGS. 1 and 2, the relative motion member 26 is disposed in contact with the driving force extracting portions 22a and 22b of the vibrator 21.

In the present embodiment, the relative movement member 26 is formed in a flat plate shape of stainless steel and arranged. Also,
The relative motion member 26 comes into pressure contact with the vibrator 21 via the driving force extracting portions 22a and 22b by a pressure support mechanism (not shown). As a result, the driving force extracting portion 22 of the vibrator 21
a, 22b in the same direction as the vibration direction of the longitudinal vibration L1 (the left-right direction in FIG. 2)
1 and a relative motion is generated.

The relative movement member 26 may be made of a copper alloy, an aluminum alloy, a polymer material or the like. In the present embodiment, the relative motion member 26 is configured as described above.

[Drive Device 30] FIG. 3 is a block diagram of the drive device 30 of the ultrasonic actuator 20 according to the present embodiment. In the following description, an example in which an A-phase drive signal is used will be described.

In FIG. 3, the voltage change of the pickup signal generated in the detection areas 23p and 23p 'provided on the vibrator 21, that is, the longitudinal vibration displacement is determined by the signal processing circuit 31.
Is input to The signal processing circuit 31 includes the detection area 23
A process of adding the two voltage values respectively input from p and 23p 'is performed.

Here, in this embodiment, as shown in FIG. 2, the detection regions 23p and 23p 'are provided at the nodal positions n ₂ and n ₄ of the bending vibration B4. For this reason, the signal added by the signal processing circuit 31 is obtained as a signal having a voltage obtained by amplifying the voltage of the longitudinal vibration L1 twice, with the voltage relating to the bending vibration B4 being zero.

The signal obtained by the addition in this manner is divided into two. One of the signals is delayed by about 90 degrees through the phase shift circuit 32 and then input to the switching circuit 33. The other is input directly to the switching circuit 33.

The direction switching circuit 33 outputs a signal whose phase is delayed to the driving circuit 34B and outputs a signal whose phase is not delayed to the driving circuit 34A. Drive circuit 3
The signals input to 4A and 34B are appropriately amplified, and input signals 23a,
3c is input to the input areas 23b and 23d.

Here, the driving device 30 includes the vibrator 21
, A detection loop 23p,
23p '→ signal processing circuit 31 → direction switching circuit 33 →
In the loop from the drive circuit 34A to the input areas 23a and 23c, the voltage applied to the input areas 23a and 23c is input, the added voltage from the signal processing circuit 31 is input, and the amplification factor and the level between the input and output are input. Assuming that the phase difference satisfies the equations and equations described above with reference to FIG.
Is set. In the present embodiment, the driving device 30 is configured as described above, and the self-excited driving is performed using the pickup signals obtained from the detection regions 23 and 23p ′.

Next, in order to drive the relative movement member 26 in a direction opposite to the above method, the signal from the signal processing
A case where self-excited drive is performed using the phase drive signal will be described.

In FIG. 3, the detection areas 23p and 23p
The pickup signal from p ′ is added by the signal processing circuit 31 and input to the direction switching circuit 33 and the phase shift circuit 32. From the signal switching circuit 33, a signal whose phase is delayed is output to the driving circuit 34A, and a signal whose phase is not delayed is input to the driving circuit 34B. The signals input to the drive circuits 34B and 34A are appropriately amplified and input to the input regions 23a and 23c. A closed loop including the vibrator 21, that is, the detection regions 23p and 23
p ′ → signal processing signal 31 → direction switching circuit 33 → drive circuit 34B → input area 23b, input voltage applied to phase B in a closed loop to 23d, and added detection area 23p from signal processing circuit 31; A voltage of 23p 'is output, and the amplification factor and phase difference between the input and output are
The equations are set so as to satisfy the equations described above with reference to FIG. In this way, even when the relative motion member 26 is driven in the reverse direction, the self-excited driving can be performed.

FIG. 4 is a circuit diagram illustrating an example of the configuration of the control device 30 shown in FIG. In FIG. 4, the same reference numerals are used for the same elements as those in FIG. In the figure, in the signal processing circuit 31, the detection area 2
The voltages from 5p and 25p 'are added by an adding circuit including resistors R1 to R7 and an amplifier IC1. Although the capacitor C1 is not always necessary in the figure, when the phase is adjusted to satisfy the above-described equations and the equations, the capacitor C1 can be used for adjustment, so that the capacitor C1 is provided. It is desirable.

Next, the voltage output from the signal processing circuit 31 is input to the phase shift circuit 32 and the direction switching circuit 33. The phase shift circuit 32 includes resistors R8 to R10, a capacitor C2, and an amplifier IC2, and delays the phase of the input voltage by approximately 90 degrees.

The direction switching circuit 33 includes a resistor R1
1 to R13, capacitors C3 and C4, an analog switch IC3, and switches SW1 and SW2.
The analog switch IC3 selects the voltage input to 0X among the voltages input to 0X and 1X when the switch SW1 is on the normal rotation side, that is, the voltage whose phase output from the signal processing circuit 31 is not delayed, Output from XC. Further, of the voltages input to 0Y and 1Y, the voltage input to 0Y, that is, the voltage output from the phase shift circuit 32 and having a phase delayed by 90 degrees is selected and output from the YC.

In this embodiment, the ultrasonic actuator 20 is started or stopped by the direction switching circuit 33. When the switch SW2 is at the stop position, the two voltages (0X, 1X and 0Y, 1Y, 1X) input from the outputs XC and YC of the analog switch IC3 are output.
Y) are not output.

As described above, by opening the closed loop including the vibrator 21 described with reference to FIG. 3 by the direction switching circuit 33, the closed loop is not formed and the self-excitation is stopped.

In the description of this embodiment, the switches SW1,
2 (dotted line), a mechanical switch is used as an example. Instead of the mechanical switch, a digital signal (for example, a TTL level signal) is directly input to the analog switch IC3 to perform switching. The same effect can be obtained.

Next, the two voltages (XC, YC) output from the direction switching circuit 33 are respectively applied to the drive circuit 3
4A and the drive circuit 34B. Drive circuit 34A
Since the drive circuit 34B and the drive circuit 34B have the same configuration, the following description will be made with respect to the drive circuit 34A.
The description and a part of the illustration of 4B are omitted.

In the driving circuit 34A, the resistors R14, R15
An amplifier is configured by the amplifier IC 4 and performs amplification. In the drive circuit 34A, the resistor R17
To R28, capacitors C5 to C11, diode D1 to
A voltage and a current necessary for driving the ultrasonic actuator 20 from the amplified voltage are supplied from a circuit constituted by D6, transistors Q1 to Q4 and a transformer L1, that is, a circuit surrounded by a dotted line in FIG. . Note that the circuit surrounded by the dotted line in the drive circuit 34A may be configured using an integrated circuit such as an audio amplifier, for example, instead of using resistors and transistors as in the present invention.

Next, the output of the driving circuit 34A is input to the input areas 23a and 23c. On the other hand, the driving circuit 34
The output of B is also input to the input areas 23b and 23d. Thus, a closed loop is formed as shown in FIG. 3, and the self-excited drive is performed. To change the moving speed of the ultrasonic actuator 20, the driving circuits 34A,
4B (see FIG. 4).
, The voltage and current output to the ultrasonic actuator 20 are changed, and the speed of the ultrasonic actuator 20 is changed. For example, when the power supply voltage is changed to a high value, the voltage and current supplied to the ultrasonic actuator 20 increase, and the speed of the ultrasonic actuator 20 increases. Conversely, when the power supply voltage supplied to the ultrasonic actuator 20 is changed to a low value, the voltage and current supplied to the ultrasonic actuator 20 decrease, and the ultrasonic actuator 2
0 speed decreases.

As described above, in the present embodiment, when the ultrasonic actuator 20 is driven by self-excitation, the driving device 30
By performing addition processing on the two pickup signals output from the two vibration detection areas 25p and 25p ′ provided at positions symmetrical to the position of the node of the longitudinal vibration L1, the frequency component of the longitudinal vibration L1 is obtained. Can be obtained with a signal strength larger than other frequency components. In order to amplify the obtained signal and feed it back to the input portion of the vibrator 21, a drive signal having a frequency substantially equal to the resonance frequency of the longitudinal vibration L1 is input to the vibrator 21 of the ultrasonic actuator 20. Can be. In the present embodiment, since the vibration detection areas 25p and 25p 'are provided at the nodes of the bending vibration B4, the signal of the frequency component of the obtained bending vibration B4 is reduced. Therefore, the signal of the frequency component of the longitudinal vibration L1 is obtained with relatively high intensity, and the signal other than the frequency component of the longitudinal vibration L1 can be prevented from self-exciting. According to the ultrasonic actuator 20 of the present embodiment, even if the role sharing of the driving force by the A-phase drive signal and the B-phase drive signal is reversed to change the direction of the linear movement, the operation characteristics change. Instead, the self-excited operation characteristics can be kept constant by changing the direction.

Further, according to this embodiment, the signal of the frequency component of the longitudinal vibration L1 is relatively stronger than the signals of the other frequency components without providing a phase correction circuit, a harmonic (spurious) suppression filter, or the like. As a result, self-excited drive by the longitudinal vibration L1 can be performed. As a result, the entire driving device can be prevented from being affected by the temperature characteristics of the phase correction circuit, the harmonic suppression filter, and the like, and the speed can be maintained while maintaining the temperature change tracking characteristic, which is an essential feature of the self-excited drive. High control accuracy can be maintained.

Therefore, according to the ultrasonic actuator 20 of the present embodiment, the influence of the individual difference of the ultrasonic actuator 20 and the influence of the environmental temperature are eliminated even by the self-excited driving.
In addition, while reducing the cost of the entire driving device 30, one of the basic controls of the ultrasonic actuator 20, that is, the change in the linear movement direction and the speed control during the movement can be reliably performed.

(Second Embodiment) Next, a second embodiment of the present invention will be described. In the following description, the first
The parts different from the embodiment will be described, and the common parts will be denoted by the same reference numerals in the drawings, and redundant description will be omitted.

FIG. 5 is a top view showing the vibrator 21-1 constituting the ultrasonic actuator 20-1 of the present embodiment. This embodiment is different from the first embodiment in the formation range of the vibration detection regions 25-1p and 25-1p '.
That is, in the present embodiment, the nodal positions n ₂ and n ₄ of the vibrator 21-1 are the same as in the first embodiment, but are not semicircular but rectangular, and the vibration detecting regions 25-1 p and 25-1 p 'Formed.

As a result, the displacement portion caused by the bending vibration B4 generated in the vibrator 21-1 is changed to the 25-1 of the vibration detection area.
In the range where p and 25-1p 'are formed, the displacement can be reduced, so that the displacement of the bending vibration that is inevitably detected by 25-1p and 25-1p' in the vibration detection area can be reduced as much as possible. Therefore, the vibration detection area 25-
An error in using the signals from 1p and 25-1p ′ for the self-excited drive can be reduced, and the accuracy of the self-excited drive can be improved. Further, according to the present embodiment, the shape of the electrode is simplified, and the productivity of the electrode is improved.

(Modification) In the description of each embodiment, the case where the vibration actuator is an ultrasonic actuator is taken as an example. However, the present invention is not limited to the ultrasonic actuator, and is similarly applied to a vibration actuator using a vibration region other than the ultrasonic wave.

In the description of each embodiment, the case where the first vibration is the longitudinal vibration and the second vibration is the bending vibration is taken as an example. However, the present invention is not limited to this embodiment, and is similarly applied to other modified mode degenerate type vibrators, homomorphic mode degenerate type vibrators, and the like.

In the description of each embodiment, the case where the order of the longitudinal vibration is the first order and the order of the bending vibration is the fourth order is taken as an example. However, the present invention is not limited to this form, and is similarly applied to other orders. For example,
The same applies to a combination of primary longitudinal vibration and secondary bending vibration, and a combination of tertiary longitudinal vibration and eighth-order bending vibration.

In the description of each embodiment, the case where two vibration detection areas are provided at different positions of the vibrator is taken as an example. However, the present invention is not limited to this mode, and two or more vibration detection regions may be provided on the vibrator.

In the description of each embodiment, an example is described in which the addition processing is performed on the signal detected from the vibration detection area. However, the present invention is not limited to this mode, and a signal relating to the first vibration is generated by performing an arithmetic process other than the addition process in accordance with the position where the vibration detection region is set on the vibrator. You may.

In the description of each embodiment, the case where the two vibration detection regions are provided at positions including the nodal positions of the bending vibration is taken as an example. However, the present invention is not limited to this form, and may be any position as long as a signal relating to the first vibration can be generated by performing appropriate arithmetic processing, and is not limited to a nodal position of bending vibration.

In the description of each embodiment, the case where the two vibration detection areas are provided at positions different from the positions including the nodal positions of the longitudinal vibration is taken as an example. However, the present invention is not limited to this mode, and is equally applicable as long as the position including the node position of the longitudinal vibration can be detected.

Further, in the description of each embodiment, an example is given in which two vibration detection areas are provided at symmetrical positions with respect to the center of the plane of the vibrator. However, the present invention is not limited to this mode, and the position does not need to be a symmetrical position as long as a signal relating to the first vibration can be generated by performing appropriate arithmetic processing.

[0068]

As described above in detail, according to the present invention, even by self-excited driving, the effects of individual differences of ultrasonic actuators and the influence of environmental temperature are eliminated, and the cost of the entire driving device is reduced. This makes it possible to reliably change the direction of linear movement, which is one of the basic controls of the ultrasonic actuator, and to control the speed during movement.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a configuration of an ultrasonic actuator according to a first embodiment.

FIG. 2 is an explanatory diagram illustrating an example of a vibration waveform generated in a vibrator of the ultrasonic actuator according to the first embodiment.

FIG. 3 is a block diagram of a driving device of the ultrasonic actuator according to the first embodiment.

FIG. 4 is an implementation circuit diagram that embodies an example of the configuration of the control device according to the first embodiment;

FIG. 5 is a top view showing a vibrator constituting an ultrasonic actuator according to a second embodiment.

FIG. 6 is a perspective view showing an ultrasonic actuator having a vibrator disclosed by Yoshiro Tomikawa on page 393 of “5th Electromagnetic Force-related Dynamic Symposium Lecture Papers”.

FIG. 7 is an explanatory diagram showing an example of two vibration waveforms generated in a vibrator of the ultrasonic actuator shown in FIG.

FIG. 8 is a block diagram showing a configuration example of a conventional self-excited drive circuit forming a vibration feedback oscillation circuit.

[Explanation of symbols]

 Reference Signs List 20 ultrasonic actuator 21 vibrator 23p, 23p 'vibration detection area 30 driving device

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H680 AA06 BB13 CC02 DD01 DD23 DD53 DD55 DD72 DD82 DD92 FF08 FF23 FF26 FF33 FF36 GG02 GG20 GG27

Claims (6)

[Claims] A first vibration that vibrates in a driving direction and a second vibration that vibrates at substantially the same frequency as the first vibration in a direction that intersects the vibration direction of the first vibration, A vibrator having at least two vibration detection regions provided at positions substantially symmetrical with respect to the node position of the first vibration, and performing arithmetic processing on two signals respectively extracted from the at least two vibration detection regions A driving signal having a frequency substantially equal to a resonance frequency of the first vibration by generating a signal relating to the first vibration and feeding back the generated signal relating to the first vibration to an input unit. And a drive device for inputting the force to the vibrator. 2. The vibration actuator according to claim 1, wherein the two vibration detection areas are provided at positions including a node position of the second vibration. 3. The vibration actuator according to claim 1, wherein the two vibration detection areas are provided at positions different from a position including a node position of the first vibration. 4. The vibration actuator according to claim 1, wherein the arithmetic processing is an addition processing. 5. The vibration according to claim 1, wherein the first vibration is a longitudinal vibration, and the second vibration is a bending vibration. Actuator. 6. The vibrator has a rectangular flat outer shape,
The vibration actuator according to any one of claims 1 to 5, wherein the two vibration detection regions are provided at symmetrical positions with respect to a center of a plane of the vibrator.