JP2007074829A - Vibration actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vibration actuator that can be easily reduced in size and simplified and can detect the vibration of a vibrating body with accuracy. <P>SOLUTION: The state of the vibration of the vibrating body 10 is indirectly detected by detecting the state of the vibration of a driven body 30A by a vibration detecting member 70. At least either of the frequency or amplitude of a driving signal imparted to the vibrating body 10 is controlled based on the result of this detection. Thus, driving signals can be controlled without directly adding a vibration detector to the vibrating body 10. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vibration actuator that drives a driven body.

  Conventionally, a vibration actuator that drives an object to be driven using an ultrasonic motor is known.

  In this vibration actuator, the vibration state of the vibration body is always detected by a vibration detector attached to the vibration body (stator), and the frequency of the drive signal or the drive signal is maintained so that the vibration body is maintained in an optimum resonance state. It is common to perform feedback control for adjusting the vibration phase and the like.

  In addition, when a plurality of ultrasonic motors are used to drive a rotating body such as a single rotating shaft or a rotating cylinder, the vibration state of each ultrasonic motor is detected and both ultrasonic motors can be driven. A technique for adjusting various control parameters is proposed (for example, Patent Document 1).

JP 7-39173 A

  However, in the technique proposed in Patent Document 1, it is necessary to add a vibration detector to the ultrasonic motor that is a vibrating body. Therefore, if it is attempted to downsize the vibration actuator and simplify the structure, vibration detection is required. The place where the device is provided is limited, and vibration detection accuracy may be reduced. That is, it is difficult to reduce the size and simplify the vibration actuator.

  In addition, by directly adding the vibration detector to the vibrating body, the vibration characteristics of the vibrating body are affected. Therefore, it is necessary to sufficiently consider the vibration design, which is a restriction on the design of the vibrating body.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a vibration actuator that can detect vibration of a vibrating body with high accuracy while easily realizing downsizing and simplification of the vibration actuator. And

  In order to solve the above problems, the invention of claim 1 is a vibration actuator for driving a driven body, wherein the vibration generating means drives the driven body by generating vibration, and the driven At least one of a frequency, an amplitude, and a phase of a drive signal applied to the vibration generation unit based on a detection result by the vibration detection unit and a vibration detection unit that detects the vibration of the driven body. And a control means for controlling one.

  The invention according to claim 2 is the vibration actuator according to claim 1, wherein the control means generates an electromotive voltage generated according to the vibration of the driven body detected by the vibration detection means and the drive signal. The frequency is controlled so that the phase difference between and becomes a predetermined target value.

  The invention according to claim 3 is the vibration actuator according to claim 1, wherein the vibration detecting means changes the frequency of the drive signal within a predetermined range, and the driven body is driven by the control means. An electromotive voltage generated in response to the vibration is detected, and the control means controls the frequency to a value that maximizes the amplitude of the electromotive voltage detected by the vibration detecting means.

  According to a fourth aspect of the present invention, there is provided the vibration actuator according to any one of the first to third aspects, wherein the vibration generating means and the driven body are in contact with each other, the vibration detecting means, and the vibration detecting means. A contact portion with the driven body is substantially opposed to the driven body with the driven body interposed therebetween.

  The invention according to claim 5 is the vibration actuator according to any one of claims 1 to 4, wherein the vibration generating means includes a piezoelectric element, and vibration is generated by the piezoelectric element. The vibration detecting means has a piezoelectric element, and can generate a vibration by the piezoelectric element to drive the driven body, and by detecting an electromotive voltage generated in the piezoelectric element, It is characterized by detecting vibration of a driven body.

  According to the first aspect of the present invention, vibration is controlled by controlling at least one of the frequency, amplitude, and phase of the drive signal applied to the vibration generating means based on the detection result of vibration of the driven body. It is possible to perform feedback control of the drive signal without adding a vibration detector directly to the body. Therefore, it is possible to detect vibration of the vibrating body with high accuracy while easily realizing downsizing and simplification of the vibration actuator.

  According to the second aspect of the invention, the frequency of the drive signal is controlled so that the phase difference between the electromotive voltage detected according to the vibration of the driven body and the drive signal becomes a predetermined target value. Thus, the vibrating body can be easily set to an appropriate resonance state.

  According to the third aspect of the present invention, the frequency of the drive signal is detected by detecting the electromotive voltage according to the vibration of the driven body while changing the frequency of the drive signal within a predetermined range. By controlling to a value that maximizes the amplitude of, the vibrator can be reliably set to an appropriate resonance state.

  According to the fourth aspect of the present invention, the contact portion between the vibration generating means and the driven body and the contact portion between the vibration detecting means and the driven body are substantially opposed with the driven body interposed therebetween. By doing so, the vibration detection accuracy can be further increased.

  According to the invention described in claim 5, the vibration generating means generates vibration by the piezoelectric element, and the vibration detecting means can drive the driven body by generating vibration by the piezoelectric element. Since it is not necessary to provide a dedicated configuration for detecting the vibration by detecting the vibration of the driven body by detecting the electromotive voltage generated in the piezoelectric element, the manufacturing cost of the vibration actuator can be reduced. Contributes to simplification and downsizing.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
<A. Equipment overview>
<Overall configuration>
FIG. 1 is a diagram showing a configuration of a drive device (vibration actuator) 1A according to an embodiment of the present invention. FIGS. 2 and 3 are a front view and a side view showing a vibrating body 10 used in the vibration actuator 1A. It is.

  As shown in FIG. 1, the vibration actuator 1 </ b> A includes a vibrating body 10 as a driving source, one driven body (moving body) 30 </ b> A driven by the vibrating body 10, a vibrating body guide 60, and a vibration detection member 70. And. Further, between the vibrating body 10 and the vibrating body guide 60, a pressing member 40 is provided for pressing the vibrating body 10 toward the driven body 30A in the pressing direction (Z direction in the figure). Note that the vibrating body guide 60 is fixed to a housing of various devices on which the vibration actuator 1A is mounted.

<Vibrating body>
As shown in FIGS. 2 and 3, the vibrating body 10 is configured as a truss-type vibration generator using two piezoelectric elements 11 and 12. Specifically, the vibrating body 10 includes two piezoelectric elements (displacement elements) 11 and 12, a chip member 13, and a base member 14. The vibrating body 10 vibrates in response to application of a high frequency voltage (high frequency signal).

  The two piezoelectric elements 11 and 12 are arranged so as to intersect at right angles, and the end portions on the intersecting side of the piezoelectric elements 11 and 12 are joined to the chip member 13. The other ends of the piezoelectric elements 11 and 12 are joined to the base member 14. The tip member 13 is preferably formed of a material (for example, a metal material such as a cemented carbide) that can stably obtain a high coefficient of friction and obtain high wear resistance. The base member 14 is preferably formed of a material that is easy to manufacture and has high strength (for example, a metal material such as stainless steel). The piezoelectric elements 11 and 12 and the members 13 and 14 are bonded using an adhesive. As the adhesive, it is preferable to use an epoxy resin adhesive excellent in adhesive strength.

  The piezoelectric element 11 is a laminated piezoelectric element, and has a structure in which a plurality of ceramic thin plates having piezoelectric characteristics and electrodes are alternately laminated. The piezoelectric element 11 is a displacement element that expands and contracts in the stacking direction according to a change in applied voltage. The piezoelectric element 12 has the same configuration as that of the piezoelectric element 11, and expands and contracts in the stacking direction in accordance with the change in applied voltage. Specifically, when a voltage with a predetermined sign is applied to the piezoelectric element 11, the piezoelectric element 11 expands, and when a voltage with an opposite sign is applied to the piezoelectric element 11, the piezoelectric element 11 contracts. And if an alternating voltage is applied, the piezoelectric element 11 will repeat an expansion-contraction according to the period of the said alternating voltage. The same applies to the piezoelectric element 12. By applying such an alternating voltage, the piezoelectric element 11 and / or the piezoelectric element 12 can be vibrated.

  However, in this embodiment, as will be described later, only one of the two piezoelectric elements 11, 12, for example, only the piezoelectric element 11 is driven, and the vibration is transmitted to the other piezoelectric element via the base member 14 and the chip member 13. 12 to resonate both piezoelectric elements 11 and 12 with a predetermined phase difference. Then, the tip member 13 provided at the intersection of the piezoelectric elements 11 and 12 is driven to draw an ellipse (including a circle). That is, an elliptical orbit is excited on the tip member 13 of the vibrating body 10.

  By pressing the tip member 13 against, for example, a flat portion of a rod-like driven body 30A (FIG. 1), the elliptical motion of the tip member 13 can be converted into a linear motion of the driven body 30A. That is, the driven body 30A is driven using the driving force generated by the elliptical motion.

<Driven object>
As shown in FIG. 1, the driven body 30 </ b> A is a member that contacts the vibrating body 10, and a member to which the driving force from the vibrating body 10 is directly transmitted. Specifically, the driven body 30 </ b> A is caused by frictional force generated between the driven body 30 </ b> A and the vibrating body 10 while repeating contact (collision) with the vibrating body 10 and separation from the vibrating body 10 according to the vibration operation of the vibrating body 10. Driven. In other words, the vibrating body 10 drives the driven body 30A by repeating the minute movement operation accompanied by frictional contact on the surface of the driven body 30A.

  The driven body 30A is made of, for example, metal (stainless steel, aluminum, or the like). In order to prevent wear due to contact with the tip member 13, it is preferable that the surface of the driven body 30A is subjected to a surface hardening process. For example, as the driven body 30A, a material obtained by subjecting an iron-based material such as stainless steel to quenching or nitriding is used. Alternatively, aluminum that has been alumite-treated or a metal surface that has been subjected to wear-resistant coating treatment with ceramic or the like may be used as the driven body 30A. The driven body 30A may be formed of a material other than metal, for example, ceramic (alumina ceramic or zirconia ceramic). If ceramic is used, the weight can be reduced, and high rigidity and high wear resistance can be obtained.

  The driven body 30A is supported by a vibration detection member 70 that also functions as a guide member, and can smoothly move linearly in the left-right direction in the figure.

<Pressurizing member>
A pressure member 40 is provided on the opposite side (+ Z side) of the driven body 30 </ b> A with respect to the vibrating body 10. The pressure member 40 is made of an elastic member such as a coil spring, for example, and one end thereof is fixed to the base member 14 of the vibrating body 10 and the other end is fixed to the vibrating body guide 60. The vibrating body 10 is pressed against the driven body 30A with a predetermined amount of force by the urging force of the pressing member 40. In addition, since the vibration cycle of the vibrating body 10 is so short that the expansion and contraction operation of the pressing member 40 cannot follow (that is, the frequency is very high), the tip member 13 of the vibrating body 10 does not respond to the urging force of the pressing member 40. Accordingly, contact and separation can be repeated with respect to the driven body 30A. Therefore, it is possible to perform the driving operation described below.

<Vibration detection member>
As shown in FIG. 1, the vibration detecting member 70 contacts the driven body 30A in a state where the relative positional relationship can be changed (here, a slidable state), and the driven body 30A In addition to being a member that detects vibration, it also functions as a guide member that supports the driven body 30A.

  As shown in FIG. 4, the vibration detection member 70 includes a sliding member 71, a vibration detection piezoelectric element 72, and a support member 73. The support member 73 is fixed to a housing of various devices on which the vibration actuator 1A is mounted.

  The driven body 30A moves while sliding on the sliding member 71. However, since the vibration detecting member 70 receives the pressing force of the vibrating body 10, the sliding friction is generated between the driven body 30A and the sliding member 71. Works and becomes a driving resistance. Therefore, it is necessary to reduce the friction coefficient so that the friction force is sufficiently small. Therefore, the sliding member 71 may be formed of a resin such as Teflon (registered trademark), or a material on which the surface treatment for reducing the friction coefficient such as Teflon coating or DLC coating is performed on the surface of the sliding member 71. May be formed. Further, the coefficient of friction may be lowered by applying grease or a solid lubricant to the surface.

  The vibration detecting piezoelectric element 72 is composed of a piezoelectric element or the like and is sandwiched between the sliding member 71 and the support member 73. Then, the vibration detecting piezoelectric element 72 generates an electromotive force (that is, an electromotive voltage) according to the pressure variation caused by the vibration of the driven body 30A due to the vibration of the vibration body 10, and the vibration period of the vibration body 10 is calculated. An alternating voltage of the same frequency is generated. Therefore, the vibration state of the vibrating body 10 can be detected by detecting the electromotive voltage generated from the vibration detecting piezoelectric element 72 by the electromotive voltage detection unit 85 (FIG. 14) described later.

  Here, the vibration detection member 70 is provided at a position substantially opposite to the vibration body 10. In other words, the contact location between the vibrating body 10 and the driven body 30A and the contact location between the vibration detection member 70 and the driven body 30A are substantially opposed to each other with the driven body 30A interposed therebetween. When the vibration body 10 and the vibration detection member 70 are arranged in this manner, the vibration detection member 70 can detect a change in pressure from the vibration body 10 to the driven body 30A almost directly. 30A, that is, the vibration detection accuracy of the vibrating body 10 is improved.

  Here, the vibration detection member 70 is a guide member, but a separate guide member may be provided as long as the driven body 30A is sandwiched between the vibration body 10 and the vibration detection member 70.

<B. Driving principle>
Next, the driving principle in the vibrating body 10 will be described.

  FIG. 5 is a diagram illustrating a model of the driving operation by the vibrating body 10. As shown in FIG. 5, a drive signal (AC voltage) is applied to one of the piezoelectric elements 11 and 12 (here, the piezoelectric element 11) of the vibrating body 10. When such a drive signal is applied, a driving force F whose direction and size changes acts on the vibrating body 10. When such a driving force F acts on the vibrating body 10, the amplitude is amplified several times to several tens of times by the resonance phenomenon, and the vibrating body 10 vibrates relatively large. In general, a drive signal may be given to both of the two piezoelectric elements 11 and 12, but in this embodiment, a drive signal is supplied to only one of the two piezoelectric elements 11 and 12. In other words, the case of “single-phase driving” in which only a single piezoelectric element (displacement element) is driven is illustrated.

  Here, it is considered that the driving force F due to the application of the driving signal is separated into a direction N in FIG. 5 (corresponding to the pressurizing direction described above) and a direction T orthogonal to the direction N. Consider the vibration state in both the vibration system (also referred to as the first vibration system) and the vibration system in the direction T (also referred to as the second vibration system). The first vibration system and the second vibration system are each represented by a one-degree-of-freedom vibration model including a spring, a mass (weight), and a damper. Here, for simplification, the base member 14 is fixed and does not deform.

  The vibration state only by the first vibration system is expressed in association with the common mode (see FIG. 11) in which the two piezoelectric elements 11 and 12 expand and contract in the same phase. In addition, the vibration state only by the second vibration system is expressed in association with a reverse phase mode (see FIG. 12) in which the two piezoelectric elements 11 and 12 expand and contract in opposite phases. The in-phase mode is a vibration mode in which the tip member 13 vibrates in the direction N, and the reverse phase mode is a vibration mode in which the chip member 13 vibrates in the direction T.

  6 and 7 are diagrams showing the relationship between the frequency (drive frequency) of the drive signal applied to one piezoelectric element and the vibration state in each vibration system (first vibration system and second vibration system). . 6 is a diagram showing the frequency characteristics of the amplitude, and FIG. 7 is a diagram showing the frequency characteristics of the phase lag with respect to the driving force F. FIG. 6 shows a curve LA1 indicating the relationship between the drive frequency f and the amplitude of the first vibration system, and a curve LA2 indicating the relationship between the drive frequency f and the amplitude of the second vibration system. In FIG. 7, a curve LP1 indicating the relationship between the drive frequency f and the phase delay of the first vibration system, a curve LP2 indicating the relationship between the drive frequency f and the phase delay of the second vibration system, the drive frequency f, A curve LP3 showing a relationship with the difference in phase delay of the vibration system (in short, a curve showing the difference between the curves LP1 and LP2) is shown.

  As shown in FIGS. 6 and 7, the vibrations of the first vibration system and the second vibration system change in accordance with the driving frequency f. Specifically, the amplitude of each vibration system increases as the drive frequency f increases, reaches a maximum at a specific frequency (also referred to as “resonance frequency”), and then decreases. Further, the phase delay of each vibration system increases as the drive frequency f increases.

  Here, in the vibrating body 10, the parameters in the first vibration system (parameters related to the elastic coefficient, mass, and damping coefficient) are slightly different from those in the second vibration system (parameters related to the elastic coefficient, mass, and damping coefficient). It is configured.

  For this reason, as shown in FIG. 6, the resonance frequency f1 in the first vibration system and the resonance frequency f2 in the second vibration system are different from each other. Specifically, the amplitude of the first vibration system is maximized when the drive frequency f is the value f1, and the amplitude of the second vibration system is maximized when the drive frequency f is the value f2 (> f1). Further, as shown in FIG. 7, the degree of phase delay in both vibration systems is also different. Specifically, at each frequency, the phase delay in the first vibration system is larger than the phase delay in the second vibration system. Here, a case where the value f1 is smaller than the value f2 is illustrated, but conversely, the value f1 may be set larger than the value f2.

  The vibration state in the vibration body 10 is expressed as a combined vibration of the vibration in the first vibration system and the vibration in the second vibration system (see FIGS. 8 to 10), and the vibration body 10 (more specifically, the chip member 13). ) Elliptic motion. Such elliptical vibration is also referred to as elliptical vibration. The locus shape of the elliptical vibration changes according to the driving frequency.

  For example, when a drive signal having a frequency f3 is applied, a vibration state as shown in FIG. 9 occurs. More specifically, as shown in FIG. 6, since the amplitude of the first vibration system and the amplitude of the second vibration system have the same magnitude, the amplitudes in the direction T and the direction N are the same. Vibrates to draw an elliptical trajectory (ie, a circular trajectory). Further, as shown by the curves LP1 and LP2 in FIG. 7, the second vibration system has a smaller phase lag than the first vibration system, and as shown by the curve LP3 in FIG. 90 degrees. Therefore, the displacement in the direction T (+ T) is first excited, and subsequently, the phase is delayed by 90 degrees and the displacement in the direction N (+ N) is excited, so that the counterclockwise vibration is excited.

  Further, when a drive signal having a frequency smaller than the frequency f3 is given, vibration along an elliptical orbit as shown in FIG. 8 occurs, for example. At this time, since the amplitude of the first vibration system is larger than the amplitude of the second vibration system as shown in FIG. 6, the vibration vibrates so as to draw an elliptical locus in which the amplitude in the direction N is larger than the amplitude in the direction T. .

  On the other hand, when a drive signal having a frequency higher than the frequency f3 is applied, vibration along an elliptical orbit as shown in FIG. 10 occurs, for example. At this time, since the amplitude of the second vibration system is larger than the amplitude of the first vibration system as shown in FIG. 6, the vibration vibrates so as to draw an elliptical locus in which the amplitude in the direction T is larger than the amplitude in the direction N. .

  8 to 10, the second vibration system has a smaller phase lag than the first vibration system, and therefore the rotational direction of the elliptical vibration is counterclockwise. Further, since the rotation direction of the elliptical vibration can be changed by switching the piezoelectric element to which the drive signal is applied, the driven body 30A can be driven in the opposite direction.

<C. Drive control>
The resonance frequency of the vibrating body 10 varies depending on the surrounding environment such as the temperature and the load applied by the pressure member 40. In addition, the resonance frequency may vary from individual to individual due to variations in the manufacturing state of the vibrator 10. Therefore, it is necessary to adjust the driving frequency to an appropriate value in consideration of the surrounding environment and individual variations. Therefore, in the vibration actuator 1A, the vibration state of the vibrating body 10 is detected by the vibration detection member 70 or the like, and the drive frequency and the drive voltage are controlled so as to obtain an appropriate vibration state.

  Hereinafter, drive control in the vibration actuator 1A will be described.

<Theory of drive control>
In the vibrating body 10, the vibration phase changes with respect to the phase of the drive signal near the resonance frequency. When the phase difference ΔPa between the drive signal of the vibrating body 10 and the vibration of the vibrating body 10 in the first vibration system is set to a predetermined target value ΔPt, the optimum vibration state is determined by the design of the vibrating body 10. . Further, since the relationship between the phase difference ΔPa and the frequency fa of the drive signal is as shown by a curve Cv shown in FIG. 13, for example, when the target value ΔPt = 0 degrees, when the phase difference ΔPa is negative, In order to increase the phase difference ΔPa and adjust it to 0 degree, the frequency of the drive signal may be increased. On the other hand, when the phase difference ΔPa is positive, the frequency of the drive signal may be decreased in order to decrease the phase difference ΔPa and adjust it to 0 degrees. In this way, by performing feedback control such that the frequency of the drive signal is changed so that the phase difference ΔPa becomes the target value ΔPt, the phase difference ΔPa can be finally adjusted to the target value ΔPt, As a result, an optimal vibration state can always be obtained. That is, the amplitude is amplified several times to several tens of times by the resonance phenomenon, and the vibrating body 10 and thus the driven body 30A can be brought into a relatively vibrated state (resonant state). Hereinafter, the frequency of the drive signal for realizing the optimum vibration state (resonance state) of the vibrating body 10 is also referred to as “optimum frequency”.

  Further, an electromotive voltage corresponding to the vibration in the first vibration system of the vibrating body 10 can be detected by using the vibration detection member 70 or the like. Then, by detecting the amplitude of the electromotive voltage, the strength of vibration of the vibrating body 10 can be determined. After controlling the frequency of the drive signal so as to obtain the optimum vibration state as described above, the voltage of the drive signal is adjusted so that the detected value of the amplitude of the electromotive voltage becomes a predetermined value. While keeping the state constant, the output can be stabilized, and the output (speed, driving force) can be controlled as necessary.

<Specific circuit configuration>
FIG. 14 is a diagram illustrating a control circuit 80A of the vibration actuator 1A. The control as described above is specifically realized using the control circuit 80A.

  The control circuit 80A includes an MPU (Micro Processing Unit) 81, an oscillator 82, an amplifier 83, a changeover switch 84, a vibration detection member 70, an electromotive voltage detection unit 85, a phase comparison unit 86, and an amplitude detection unit 87. .

  The MPU 81 controls the oscillation frequency of the oscillator 82, the amplification factor of the amplifier 83, and the connection state of the changeover switch 84. The MPU 81 controls the oscillation frequency of the oscillator 82 based on the phase difference detection signal or the like input from the phase comparison unit 86.

  The oscillator 82 generates a sinusoidal or pulsed drive signal, and can arbitrarily set the frequency of the drive signal in accordance with a control input from the MPU 81. An output signal (drive signal) from the oscillator 82 is input to the amplifier 83. The output signal (drive signal) from the oscillator 82 is also input to the phase comparison unit 86.

  The amplifier 83 amplifies the level of the drive signal generated by the oscillator 82 to a level at which the piezoelectric element 11 or the piezoelectric element 12 can be driven. The amplified drive signal depends on the connection state of the changeover switch 84. It is selectively inputted to the piezoelectric element 11 or the piezoelectric element 12. Note that the connection state of the changeover switch 84 is switched according to a control signal from the MPU 81. Here, a case where a drive signal is input to the piezoelectric element 11 will be described. However, if a drive signal is input to the other piezoelectric element 12, reverse driving is possible.

  As described above, the oscillator 82 and the amplifier 83 supply the drive signal to only one of the two piezoelectric elements 11 and 12 with respect to the vibrating body 10. By supplying such a drive signal, the vibrating body 10 vibrates.

  The vibration state of the vibrating body 10 is indirectly detected by detecting the vibration of the driven body (moving body) 30 </ b> A by the vibration detection member 70. In the vibration detection member 70, the vibration in the first vibration system shown in FIG. 5 is detected by the built-in vibration detection piezoelectric element 72.

  In the vibration detection member 70, an electromotive force corresponding to the pressure applied to the vibration detection piezoelectric element 72 is generated in the vibration detection piezoelectric element 72, and the electromotive force is input to the electromotive voltage detection unit 85.

  The electromotive voltage detection unit 85 detects an AC voltage corresponding to the vibration cycle of the vibrating body 10 from the electromotive force input from the vibration detection member 70. The AC voltage detected by the electromotive voltage detection unit 85 is supplied to the phase comparison unit 86 and the amplitude detection unit 87.

  The phase comparison unit 86 calculates the phase difference ΔPa by comparing the phase of the AC voltage input from the electromotive voltage detection unit 85 and the drive signal input from the oscillator 82, and outputs the phase difference ΔPa to the MPU 81. Then, the MPU 81 controls the frequency of the drive signal so that the input phase difference ΔPa becomes the target value ΔPt. It is assumed that the target value ΔPt is stored in advance in a ROM or the like built in the MPU 81.

  The amplitude detector 87 detects the amplitude of the AC voltage input from the electromotive voltage detector 85 and outputs it to the MPU 81. Then, the MPU 81 compares the gain of the amplifier 83 with a predetermined value stored in a ROM or the like built in the MPU 81 so that the amplitude of the AC voltage becomes a predetermined value.

  As described above, in the vibration actuator 1A, the frequency and amplitude of the drive signal are controlled so that the vibration state of the vibrating body 10 is brought close to a predetermined target state. Specifically, at least one of the frequency and the amplitude of the drive signal given to the vibrating body 10 is controlled based on the detection result of the vibration of the driven body 30A. Thereby, it becomes possible to control the drive signal without adding a vibration detector directly to the vibrating body 10. Therefore, it is possible to detect the vibration of the vibrating body with high accuracy while easily realizing downsizing and simplification of the vibration actuator.

  Further, the frequency of the drive signal is controlled so that the phase difference ΔPa between the drive signal applied to the vibrating body 10 and the electromotive voltage detected according to the vibration of the driven body 30A becomes a predetermined target value ΔPt. As a result, the vibrating body 10 can be easily set to an appropriate resonance state.

  Further, the contact portion between the vibration body 10 and the driven body 30A and the contact portion between the vibration detection member 70 and the driven body 30A are substantially opposed to each other with the driven body 30A interposed therebetween. For this reason, the detection accuracy of the vibration of the vibrating body 10 can be further increased.

  In the vibration actuator 1A described above, the vibrating body 10 and the vibration detection member 70 are disposed substantially opposite to each other. However, the present invention is not limited to this. For example, like the vibration actuator 1Aa shown in FIG. 15, the vibration body 10 and the vibration detection member 70 are arranged at positions slightly shifted in the driving direction of the driven body 30A, and the driven body 30A May be supported by the vibration detecting member 70 and the guide member 90. That is, the driven body 30 </ b> A may be sandwiched between the set of the guide member 90 and the vibration detection member 70 and the vibrating body 10. In such a configuration, the driven body 30 </ b> A slides along the guide member 90 and the vibration detection member 70 by vibrating the vibrating body 10. The guide member 90 is fixed to a housing of various devices on which the vibration actuator 1Aa is mounted.

  However, when the vibration body 10 and the vibration detection member 70 are misaligned as in the vibration actuator 1Aa shown in FIG. 15, the vibration of the vibration body 10 is accurately detected by the vibration of the driven body 30A. It is not detected by the member 70, and the phase of vibration is detected with a slight shift. Therefore, in such a case, it is necessary to set a predetermined target value ΔPt that is corrected according to the arrangement. The corrected predetermined target value ΔPt is obtained by detecting the vibration state by the vibration detecting member 70 while actually changing the deviation amount between the vibrating body 10 and the vibration detecting member 70. Can be determined.

  However, in consideration of vibration detection accuracy, it is preferable that the vibration body 10 and the vibration detection member 70 are substantially opposed to each other as in the vibration actuator 1A described above. It is more preferable to oppose to.

Second Embodiment
In the vibration actuator 1A according to the first embodiment described above, only one vibration body 10 is used. However, in the vibration actuator 1B according to the second embodiment, two vibration bodies 10 are used. Hereinafter, the vibration actuator 1B according to the second embodiment will be described with the same reference numerals assigned to the same portions as those of the vibration actuator 1A according to the first embodiment and the description thereof omitted.

  FIG. 16 is a diagram showing a configuration of a vibration actuator 1B according to the second embodiment of the present invention.

  As shown in FIG. 16, unlike the vibration actuator 1A according to the first embodiment, the vibration actuator 1B according to the second embodiment has the same configuration as the vibration body 10 above the driven body 30A in the drawing. A first vibrating body 10a and a second vibrating body 10b are provided. In this way, by driving the driven body 30A by the plurality of vibrating bodies 10a and 10b, the driving force is multiplied by the number.

  Here, a method for setting the frequency of the drive signal will be described.

  Here, similarly to the vibration actuator 1A according to the first embodiment having only one vibrating body 10, the electromotive force of the vibration detecting piezoelectric element 72 of the vibration detecting member 70 is detected to determine the frequency of the drive signal. To do. However, since there are two vibrating bodies, when detecting the vibration of one vibrating body 10a, the other vibrating body 10b is stopped and when detecting the vibration of the other vibrating body 10b. Then, one vibrating body 10a is stopped. This is because when the two vibrating bodies 10a and 10b are driven simultaneously, the vibration of the driven body 30A is a mixture of the vibrations of the two vibrating bodies 10a and 10b. This is because the state cannot be detected. At this time, the driven body 30A is held in a stopped state due to friction generated between the driven body 30A and the stop-side vibrating body (vibrating body 10a or vibration pair 10b).

  Thus, when the vibration state is detected for each vibrating body, the phase difference ΔPa between the driving signal and the electromotive voltage is obtained for the first vibrating body 10a, and the driving signal and the electromotive voltage are also calculated for the second vibrating body 10b. A phase difference ΔPb is obtained. Thus, since the two phase differences ΔPa and ΔPb are obtained, the frequency (optimum frequency) of the drive signal for realizing the optimum vibration state is obtained for each of the first vibrating body 10a and the second vibrating body 10b. Can do.

  At this time, for example, each of the vibrators 10a and 10b may be driven by inputting a drive signal having the optimum frequencies fa and fb, or a drive signal having one of the optimum frequencies fa and fb is input. The driving signal may be driven, or may be driven by inputting a driving signal having an average frequency (fa + fb) / 2 of the optimum frequency. However, when the plurality of vibrating bodies 10a and 10b are vibrated simultaneously, if the frequency of the driving signal of each vibrating body is different, a sound having a difference period is generated. Therefore, the plurality of vibrating bodies are generated by the driving signal having the same frequency. It is preferable to drive 10a and 10b.

  FIG. 17 is a diagram illustrating a control circuit 80B of the vibration actuator 1B. The control as described above is specifically realized using the control circuit 80B. In FIG. 17, attention is focused on the configuration related to the determination of the frequency of the drive signal, and the configuration of the amplitude detection unit 87 and the like for controlling the amplitude of the drive signal is omitted as compared with FIG. 14.

  Hereinafter, the control circuit 80B will be described with the same components as those of the control circuit 80A having the same reference numerals and the description thereof being omitted.

  In the control circuit 80B, unlike the configuration of the control circuit 80A, whether the drive signal output from the amplifier 83 is input to the first vibrating body 10a or the second vibrating body 10b is changed to two changeover switches 84a, Switching is performed according to the connection state 84b. Note that the connection state of the changeover switches 84 a and 84 b is switched by the MPU 81.

  Here, when the frequency is determined based on one of the vibrating bodies (for example, the first vibrating body 10a), a drive signal is input to the piezoelectric element 11 of the first vibrating body 10a as in the first embodiment. Then, the electromotive voltage output from the vibration detection member 70 is detected by the electromotive voltage detector 85 while vibrating the first vibrating body 10a. Then, the phase comparator 86 calculates the phase difference ΔPa between the drive signal input from the oscillator 82 and the AC voltage input from the electromotive voltage detector 85, and the MPU 81 sets the phase difference ΔPa to a predetermined target value ΔPt. The frequency of the drive signal is controlled so that

  On the other hand, when the average value of the optimum frequencies fa and fb for the two vibrating bodies 10a and 10b is set as the frequency of the drive signal, the optimum frequency is determined by the two changeover switches 84a and 84b under the control of the MPU 81. A drive signal is input to the vibrating body.

  For example, by inputting a driving signal to the first vibrating body 10a, the optimum frequency fa for the first vibrating body 10a is obtained in the same manner as in the first embodiment, and then the driving signal is input to the second vibrating body 10b. Thus, the optimum frequency fb for the second vibrating body 10b is obtained by the same method as in the first embodiment. Then, the MPU 81 calculates an average value of the optimum frequencies fa and fb, and performs control such that both vibrators 10a and 10b are driven using the value as the frequency of the drive signal.

  As described above, also in the vibration actuator 1B according to the second embodiment, it is possible to control the drive signal without adding a vibration detector directly to the vibrating body 10. For this reason, it is possible to detect the vibration of the vibrating body with high accuracy while easily realizing downsizing and simplification of the vibration actuator.

<Third Embodiment>
The vibration actuators 1A and 1B according to the first and second embodiments described above include the vibration detection member 70 that is a dedicated member for detecting the vibration of the driven body 30A, but the vibration actuator 1C according to the third embodiment. Then, the vibrating body plays a role of detecting the vibration of the driven body 30A. In the vibration actuator 1C according to the third embodiment, a vibration body 10d is provided instead of the vibration detection member 70, as compared with the vibration actuator 1Aa shown in FIG. Hereinafter, the vibration actuator 1 </ b> C according to the third embodiment will be described with the same reference numerals assigned to the same portions as those of the vibration actuator 1 </ b> Aa according to the modification of the first embodiment, and description thereof omitted.

  FIG. 18 is a diagram showing a configuration of a vibration actuator 1C according to the third embodiment of the present invention.

  As shown in FIG. 18, in the vibration actuator 1C, an upper vibration body (hereinafter also referred to as “upper vibration body”) 10u and a lower vibration body (hereinafter also referred to as “lower vibration body”) 10d in the figure. However, they are not substantially opposed to each other, but are arranged at positions slightly deviated from each other in the driving direction of the driven body 30A. The driven body 30A is supported by the lower vibrating body 10d and the guide member 90. That is, the driven body 30A is sandwiched between the set of the guide member 90 and the lower vibrating body 10d and the upper vibrating body 10u.

  The upper vibrating body 10u and the lower vibrating body 10d have the same configuration as the vibrating body 10 in the above-described embodiment.

  The lower vibrating body 10d is fixed to a housing of a device on which the vibration actuator 1C is mounted, and the upper vibrating body 10u is pressed against the driven body 30A by a predetermined pressing force from the pressing member 40. The driven body 30A moves along the guide member 90 and the lower vibrating body 10d.

  Here, a method of setting the frequency of the drive signal in the vibration actuator 1C will be described.

  When only the lower vibrating body 10d is vibrated, an electromotive voltage corresponding to a pressure change due to vibration of the lower vibrating body 10d is generated in the piezoelectric element of the upper vibrating body 10u. This electromotive voltage is an AC voltage having the same cycle as the frequency of vibration generated by the lower vibrating body 10d (vibration frequency). At this time, the driven body 30A is held in a stopped state due to friction generated between the driven body 30A and the upper vibrating body 10u. Conversely, when only the upper vibrating body 10u is vibrated, an electromotive voltage corresponding to the vibration of the upper vibrating body 10u is generated in the piezoelectric element of the lower vibrating body 10d. Thus, the mutual vibration state can be detected by the two vibrating bodies 10u and 10d.

  When the vibration state is detected for each vibrator, the phase difference ΔPu between the drive signal and the electromotive voltage is obtained for the upper vibrator 10u, and the phase difference ΔPd between the drive signal and the electromotive voltage is obtained for the lower vibrator 10d. . As described above, since the two phase differences ΔPu and ΔPd are obtained, drive signals for realizing optimal vibration states for the upper vibrating body 10u and the lower vibrating body 10d by the same method as in the first embodiment described above. Frequency (optimal frequencies) fu and fd can be obtained respectively.

  At this time, for example, each of the vibrators 10u and 10d may be driven by inputting a drive signal having optimum frequencies fu and fd, or a drive signal having one of the optimum frequencies fu and fd is inputted. The driving signal may be driven, or may be driven by inputting a driving signal having a frequency of an average value (fu + fd) / 2 of the optimum frequency.

  FIG. 19 is a diagram illustrating a control circuit 80C of the vibration actuator 1C. The control as described above is specifically realized by using the control circuit 80C. In FIG. 19, the configuration related to the determination of the frequency of the drive signal is focused, and the configuration for controlling the amplitude of the drive signal is omitted.

  Hereinafter, the control circuit 80C will be described with the same reference numerals assigned to the same configuration as the control circuit 80A and the description thereof omitted.

  In the control circuit 80C, unlike the configuration of the control circuit 80A, whether the drive signal output from the amplifier 83 is input to the upper vibration body 10u or the lower vibration body 10d is determined by the two changeover switches 841 and 842. Switch according to the connection status. The connection state of the changeover switches 841 and 842 is switched by the MPU 81. Moreover, the 1st and 2nd electromotive force detection parts 851 and 852 which each detect the electromotive voltage output from each vibrating body 10u and 10d are provided. In addition, a changeover switch 88 is provided for switching which one of the first and second electromotive voltage detectors 851 and 852 outputs the electromotive voltage output to the phase comparator 86. The connection state of the selector switch 88 is switched by the MPU 81.

  Here, when the frequency is determined based on one of the vibrating bodies (for example, the upper vibrating body 10u), a drive signal is input to the piezoelectric element 11 of the upper vibrating body 10u as in the first embodiment. The second electromotive force detection unit 852 detects the electromotive voltage output from the lower vibrating body 10d while vibrating the upper vibrating body 10u. The phase comparator 86 calculates a phase difference ΔPu between the drive signal input from the oscillator 82 and the AC voltage input from the second electromotive voltage detector 852, and the MPU 81 sets the phase difference ΔPu to a predetermined target. The frequency of the drive signal is controlled so that the value ΔPt is obtained. At this time, by applying the optimum frequency fu for the upper vibrating body 10u to the drive signal input to the lower vibrating body 10d, the vibration actuator 1C can be brought into an appropriate vibration state.

  On the other hand, when the average value of the optimum frequencies fu and fd for the two vibrators 10u and 10d is used as the frequency of the drive signal, the MPU 81 controls the two changeover switches 841 and 842 to obtain the optimum frequency. A drive signal is input to the vibrating body.

  For example, by inputting a driving signal to the upper vibrating body 10u, an optimum frequency fu for the upper vibrating body 10u is obtained in the same manner as in the first embodiment, and then, a driving signal is input to the lower vibrating body 10d. The optimum frequency fd for the lower vibrating body 10d is obtained by the same method as in the first embodiment. Then, the MPU 81 calculates an average value of the optimum frequencies fu and fd, and performs control to drive both vibrators 10u and 10d using the value as the frequency of the drive signal.

  As described above, in the vibration actuator 1C according to the third embodiment, the upper and lower vibrating bodies 10u. 10d generates vibration by the piezoelectric element. And each vibrating body 10u. 10d makes it possible to drive the driven body 30A by generating vibration by the piezoelectric element, and to detect an electromotive voltage generated in the piezoelectric element of the other vibrating body when one vibrating body is vibrated. Then, the vibration of the driven body is detected. Therefore, there is no need to provide a dedicated configuration for detecting the vibration of the driven body 30A, which contributes to a reduction in manufacturing cost, simplification, and miniaturization of the vibration actuator 1C.

<Fourth embodiment>
In the vibration actuator 1C according to the third embodiment described above, the two vibrating bodies 10u and 10d are arranged at positions slightly shifted from each other with respect to the direction in which the driven body 30A is driven. On the other hand, in the vibration actuator 1D according to the fourth embodiment, the two vibrating bodies 10u and 10d are arranged at positions substantially opposed to each other with the driven body 30A interposed therebetween. Hereinafter, the same parts as those of the vibration actuator 1C according to the third embodiment will be denoted by the same reference numerals and description thereof will be omitted, and the vibration actuator 1D according to the fourth embodiment will be described.

  FIG. 20 is a diagram showing a configuration of a vibration actuator 1D according to the fourth embodiment of the present invention.

  As shown in FIG. 20, in the vibration actuator 1D, the upper vibration body (upper vibration body) 10u in the drawing and the lower vibration body (lower vibration body) 10d in the drawing are substantially opposed to each other with the driven body 30A interposed therebetween. It is arranged at the position to do. From another viewpoint, the contact portion between the upper vibrating body 10u and the driven body 30A and the contact portion between the lower vibration body 10d and the driven body 30A are substantially opposed to each other with the driven body 30A interposed therebetween. ing.

  The lower vibrating body 10d is pressed against the driven body 30A from below in the figure by a predetermined pressing force from the pressing member 40, similarly to the upper vibrating body 10u. The pressurizing member 40 that applies a pressing force to the lower vibrating body 10d is fixed to the vibrating body guide 60. Further, the vibrating body guide 60 is fixed to a casing of a device on which the vibration actuator 1D is mounted. The

  Then, similarly to the vibration actuator 1C according to the third embodiment, the vibration state of one vibration body can be detected by the other vibration body. When the upper vibrating body 10u and the lower vibrating body 10d are arranged so as to face each other, one of the vibrating bodies can almost directly detect a change in pressure on the driven body 30A by the other vibrating body. The vibration detection sensitivity, that is, the detection accuracy is improved.

  The driven body 30A is held by being sandwiched between the upper vibrating body 10u and the lower vibrating body 10d, and the driven body 30A is moved by simultaneously vibrating the upper and lower vibrating bodies 10u and 10d. Can do. It should be noted that a method similar to that in the third embodiment can be applied to the control method of the drive signals input to the upper and lower vibrating bodies 10u, 10d so that the vibration actuator 1D is in an optimal driving state. .

  However, when the upper vibrating body 10u and the lower vibrating body 10d face each other, there are the following problems.

  As already described in the above-described embodiment, the upper and lower vibrating bodies 10u and 10d have a large phase lag of vibration with respect to the drive signal in the vicinity of the resonance frequency, so that they are shifted to the resonance frequencies of the two vibrating bodies 10u and 10d. If there is, there is a difference in the phase of vibration of the two vibrating bodies 10u and 10d with respect to the same drive signal. If the vibration phases of the two vibrating bodies 10u and 10d are out of phase, for example, when one vibrating body 10u presses the driven body 30A, the other vibrating body 10d moves away from the driven body 30A. An attempt is made to move the driven body 30A. At this time, the other vibrating body 10d tends to be separated, but the pressing of the one vibrating body 10u makes it difficult for the vibrating body 10d to be separated from the driven body 30A, and the driving of the vibrating body 10d becomes the movement of the driven body 30A. The brake will be applied. Therefore, in the vibration actuator 1D, in order to move the driven body 30A with high efficiency, it is preferable to drive the two vibration bodies 10u and 10d in synchronization with each other.

  Here, a method for synchronizing the vibrations of the two vibrating bodies 10u and 10d will be described.

  Similarly to the third embodiment, when only the lower vibrating body 10d is vibrated, an alternating voltage corresponding to a pressure change caused by the vibration of the lower vibrating body 10d is generated in the piezoelectric element of the upper vibrating body 10u, and conversely, the upper vibrating body 10u. When only this is vibrated, an AC voltage corresponding to the vibration of the upper vibrating body 10u is generated in the piezoelectric element of the lower vibrating body 10d. Then, by using the same method as in the third embodiment, for example, the optimal frequency of the drive signal is obtained for either or both of the upper and lower vibrating bodies 10u and 10d, and an appropriate vibration state of the vibration actuator 1D is obtained. The frequency of the drive signal (hereinafter also referred to as “appropriate drive frequency”) can be set. For example, for both the upper and lower vibrating bodies 10u and 10d, the optimum frequencies fu and fd of the drive signal can be obtained, and the appropriate drive frequency of the drive signal can be set to an average value (fu + fd) / 2.

  With the drive signal set to an appropriate drive frequency as described above, the phase difference ΔPu between the drive signal and the electromotive voltage generated from the lower vibrator 10d is obtained for the upper vibrator 10u, and the lower vibrator 10d is obtained. Also, the phase difference ΔPd between the drive signal and the electromotive voltage generated from the upper vibrating body 10u is obtained. At this time, the phase difference difference value (= ΔPu−ΔPd) corresponds to a vibration phase difference between the upper vibrating body 10 u and the lower vibrating body 10 d (hereinafter also referred to as “vibration phase difference”). Therefore, the vibrations of the upper vibrator 10u and the lower vibrator 10d can be synchronized by shifting the phases of the drive signals input to the upper vibrator 10u and the lower vibrator 10d by this vibration phase difference.

  FIG. 21 is a diagram illustrating a control circuit 80D of the vibration actuator 1D. The above-described phase control is specifically realized using the control circuit 80D. In FIG. 21, attention is paid to the configuration related to the control of the phase of the drive signal, and the configuration for controlling the amplitude of the drive signal is omitted.

  Hereinafter, the control circuit 80D will be described with the same reference numerals assigned to the same configuration as the control circuit 80C (FIG. 19) and description thereof omitted.

  The control circuit 80D is different from the control circuit 80C in that a phase shifter 89 that shifts the phase of the drive signal is added between the amplifier 83 and the lower vibrating body 10d.

  Here, by appropriately switching the connection state of the two change-over switches 84a and 84b, a driving signal set to an appropriate driving frequency is input only to the upper vibrating body 10u to vibrate the upper vibrating body 10u. At this time, the electromotive voltage output from the piezoelectric element of the lower vibrating body 10d is detected by the second electromotive voltage detection unit 852, and the phase comparison unit 86 detects the electromotive voltage (AC voltage) detected by the second electromotive voltage detection unit 852. ) And the drive signal input from the oscillator 82 is calculated and input to the MPU 81.

  On the other hand, a driving signal set at an appropriate driving frequency is input only to the lower vibrating body 10d to vibrate the lower vibrating body 10d. At this time, the electromotive voltage output from the piezoelectric element of the upper vibrating body 10a is detected by the first electromotive voltage detection unit 851, and the phase comparison unit 86 detects the electromotive voltage (AC voltage) detected by the first electromotive voltage detection unit 851. ) And the drive signal input from the oscillator 82 is calculated and input to the MPU 81.

  Then, the MPU 81 calculates a difference value (= ΔPu−ΔPd) between the two phase differences ΔPu and ΔPd. Since this value corresponds to the vibration phase difference between the upper vibrating body 10a and the lower vibrating body 10d, the difference value (= ΔPu−ΔPd) is input to the phase shifter 89, whereby the drive signal input to the lower vibrating body 10d. Is shifted by a difference value (= ΔPu−ΔPd) with respect to the phase of the drive signal input to the upper vibration body 10a, so that the phase of vibration between the upper vibration body 10a and the lower vibration body 10d ( (Oscillation phase) can be matched and synchronized.

  For example, when ΔPu is −20 degrees and ΔPd is 20 degrees, the difference value (= ΔPu−ΔPd) = − 40 degrees is calculated. When the difference value = −40 degrees, the vibration phase of the lower vibration body 10d is delayed by 40 degrees with respect to the vibration phase of the upper vibration body 10u. Therefore, by shifting the phase of the drive signal input to the lower vibrating body 10d by 40 degrees by the phase shifter 89, the phases of vibrations of the upper vibrating body 10a and the lower vibrating body 10d can be synchronized. .

  As described above, in the vibration actuator 1D according to the fourth embodiment, the upper vibration body 10a and the lower vibration body 10d are arranged to face each other so as to sandwich the driven body 30A. Then, the drive signal is controlled so as to synchronize the phases of vibrations of the upper vibrator 10a and the lower vibrator 10d. In other words, the phase of the drive signal given to the two vibrating bodies 10u and 10d is controlled based on the detection result of the vibration of the driven body 30A. With such a configuration, the driven body 30A can be moved with high efficiency.

  In the vibration actuator 1D according to the fourth embodiment, similarly to the vibration actuators 1A to 1C according to the first to third embodiments, the drive given to the vibration body 10 based on the detection result of the vibration of the driven body 30A. The frequency and amplitude of the signal can also be controlled to drive the vibration actuator 1D more appropriately. That is, the vibration actuator 1D controls at least one of the frequency, amplitude, and phase of the drive signal applied to the lower vibrating body 10d based on the vibration detection result of the driven body 30A according to the situation. Thus, the vibration actuator 1D can be appropriately driven. And such control can be performed without adding a vibration detector directly to a vibrating body. That is, it is possible to detect vibrations of the vibrating body with high accuracy while easily realizing downsizing and simplification of the vibration actuator.

<Modification>
As mentioned above, although embodiment of this invention was described, this invention is not limited to the thing of the content demonstrated above.

  For example, in the above-described embodiment, the MPU 81 controls the frequency of the drive signal in accordance with the phase difference (for example, the phase difference ΔPa) input from the phase comparison unit 86. The frequency of the drive signal generated from the oscillator 82 may be controlled so that the phase difference becomes ΔPt.

  In the first embodiment described above, control is performed so that the difference between the phase of the drive signal and the phase of the electromotive voltage detected by using the vibration detection member 70, that is, the phase difference ΔPa matches the predetermined target value ΔPt. However, the present invention is not limited to this. For example, the vibration detection member 70 and the electromotive voltage detection unit 85 are used while changing the frequency of the drive signal within a predetermined range. An electromotive voltage corresponding to the vibration of the driven body 30A may be detected, and the frequency of the drive signal may be controlled to a value that maximizes the amplitude of the detected electromotive voltage. Here, it is used that the electromotive voltage of the vibration detection member 70 becomes maximum at the frequency of the drive signal at which the vibration of the vibrating body 10 becomes maximum. That is, it is utilized that the frequency of the drive signal and the amplitude of the electromotive voltage have a relationship (curve Cv1) that maximizes the amplitude of the electromotive voltage at a certain frequency fmax as shown in FIG.

  Note that the predetermined value range that changes the frequency of the drive signal may be, for example, a predetermined value range near the resonance frequency of the vibrator 10 that is designed in advance.

  FIG. 23 is a diagram illustrating an example of a control circuit 80E for specifically realizing the above-described control. This control circuit 80E is a control circuit applicable when it has the same configuration as the vibration actuator 1A of the first embodiment.

  The control circuit 80E is similar to the control circuit 80A according to the first embodiment except that the phase comparison unit 86 is not present, and the other configurations are the same. The reference numerals are attached and the description is omitted.

  In this control circuit 80E, an electromotive voltage (alternating voltage) output from the vibration detecting member 70 is generated while changing the frequency of the drive signal input to the vibrating body 10 within a predetermined range within the control of the MPU 81. Detection is performed by the detection unit 85. Then, the amplitude of the electromotive voltage input from the electromotive voltage detection unit 85 is detected by the amplitude detection unit 87. Then, the MPU 81 detects the frequency of the drive signal that maximizes the amplitude of the electromotive voltage, and controls the frequency of the drive signal to a value that maximizes the amplitude of the detected electromotive voltage.

  By such control, it is possible to reliably set the vibrating body 10 to an optimal resonance state. And such control is applicable also to the structure of other embodiment. However, with such control, the drive signal can be set to an optimal frequency more reliably at the start of vibration of the vibrator 10, but the amplitude of the electromotive voltage is detected while changing the frequency within a certain range of values. Otherwise, it cannot be determined whether the frequency of the drive signal should be increased or decreased. On the other hand, in the first embodiment described above, it is easily determined whether to increase or decrease the frequency of the drive signal depending on whether the phase difference ΔPa is shifted positively or negatively from the target value ΔPt. be able to. Therefore, considering that timely feedback control is performed during vibration of the vibrating body 10, it is preferable to use a method of adjusting the phase difference ΔPa to the target value ΔPt.

  In the third embodiment described above, the two vibrating bodies 10u and 10d are arranged so as to sandwich the driven body 30A, but the present invention is not limited to this. For example, like the vibration actuator 1Ca shown in FIG. The two vibrating bodies 10a and 10b may be arranged so as to press the driven body 30A from the upper side in the figure, and the driven body 30A may be supported by the two guide members 90 and 91 from the lower side in the figure. Even with such a configuration, the drive of the vibration actuator 1Ca can be controlled by the same method as in the third embodiment.

  In the above-described first embodiment, sliding friction is generated between the vibration detection member 70 and the driven body 30A, so that resistance to driving occurs and efficiency is reduced. Therefore, for example, by using the sliding member 71 of the vibration detecting member 70 as a rotating body such as a roller, rolling friction with a small resistance may be used. In this case, a vibration detecting piezoelectric element may be provided on the rotating shaft of the roller.

  In addition, as a modification of the above-described fourth embodiment, for example, one having a configuration as shown in FIGS. In the configuration shown in FIG. 25, the two vibrating bodies 10u and 10d face each other and sandwich the rotating body 30B as the driven body, and the two vibrating bodies 10u and 10d are vibrated to rotate the rotating body 30B. be able to. In the configuration shown in FIG. 26, the driven body 30C is held by the two vibrating bodies 10u and 10d by applying a pressing force in the opposite directions from the inside of the ring-shaped driven body 30C. The rotating body 30C can be rotated by vibrating the vibrating bodies 10u and 10d.

It is a figure which shows the structure of the vibration actuator which concerns on 1st Embodiment. It is a front view which shows the vibrating body used for a vibration actuator. It is a side view which shows the vibrating body used for a vibration actuator. It is a figure which shows the structure of a vibration detection member. It is a figure which shows the model of the drive operation by a vibrating body. It is a figure which shows the relationship between the drive frequency provided to a piezoelectric element, and a vibration state. It is a figure which shows the relationship between the drive frequency provided to a piezoelectric element, and a vibration state. It is a figure which illustrates the locus shape of elliptical vibration. It is a figure which illustrates the locus shape of elliptical vibration. It is a figure which illustrates the locus shape of elliptical vibration. It is a figure which illustrates the drive of the common mode of a vibrating body. It is a figure which illustrates the drive in the reverse phase mode of a vibrating body. It is a figure for demonstrating the theory of drive control. It is a figure which shows the control circuit of the vibration actuator which concerns on 1st Embodiment. It is a figure which shows the modification of a structure of a vibration actuator. It is a figure which shows the structure of the vibration actuator which concerns on 2nd Embodiment. It is a figure which shows the control circuit of the vibration actuator which concerns on 2nd Embodiment. It is a figure which shows the structure of the vibration actuator which concerns on 3rd Embodiment. It is a figure which shows the control circuit of the vibration actuator which concerns on 3rd Embodiment. It is a figure which shows the structure of the vibration actuator which concerns on 4th Embodiment. It is a figure which shows the control circuit of the vibration actuator which concerns on 4th Embodiment. It is a figure which shows the relationship between the frequency of a drive signal, and the amplitude of an electromotive voltage. It is a figure which shows the control circuit of the vibration actuator which concerns on a modification. It is a figure which shows the structure of the vibration actuator which concerns on a modification. It is a figure which shows the structure of the vibration actuator which concerns on a modification. It is a figure which shows the structure of the vibration actuator which concerns on a modification.

Explanation of symbols

1A to 1E Vibration actuator (drive device)
DESCRIPTION OF SYMBOLS 10 Vibration body 10a 1st vibration body 10b 2nd vibration body 10u Upper vibration body 10d Lower vibration body 30A-30B Driven body 70 Vibration detection member 80A-80E Control circuit 81 MPU
82 Oscillator 83 Amplifier 84, 84a, 84b, 88, 841, 842 Changeover switch 85 Electromotive voltage detection unit 86 Phase comparison unit 87 Amplitude detection unit 90, 91 Guide member 851 First electromotive voltage detection unit 852 Second electromotive voltage detection unit

Claims (5)

A vibration actuator for driving a driven body,
Vibration generating means for driving the driven body by generating vibration;
Vibration detecting means for contacting the driven body and detecting the vibration of the driven body;
Control means for controlling at least one of the frequency, amplitude, and phase of the drive signal applied to the vibration generating means based on the detection result by the vibration detecting means;
A vibration actuator comprising: The vibration actuator according to claim 1,
The control means is
A vibration actuator characterized by controlling the frequency so that a phase difference between an electromotive voltage generated according to vibration of the driven body detected by the vibration detecting means and the drive signal becomes a predetermined target value. . The vibration actuator according to claim 1,
While detecting the electromotive voltage generated according to the vibration of the driven body in the vibration detecting means while changing the frequency of the drive signal within a predetermined range by the control means,
The control means is
A vibration actuator, wherein the frequency is controlled to a value at which an amplitude of the electromotive voltage detected by the vibration detection means is maximized. The vibration actuator according to any one of claims 1 to 3,
A vibration actuator characterized in that a contact portion between the vibration generating means and the driven body and a contact portion between the vibration detecting means and the driven body are substantially opposed to each other with the driven body interposed therebetween. . The vibration actuator according to any one of claims 1 to 4,
The vibration generating means is
Having a piezoelectric element and generating vibration by the piezoelectric element;
The vibration detecting means is
It is possible to drive the driven body by having a piezoelectric element and generating vibration by the piezoelectric element, and by detecting an electromotive voltage generated in the piezoelectric element, the vibration of the driven body is detected. The vibration actuator characterized by detecting.

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